Low←tech Magazine

2007-2012

Kris De Decker

Contents

Introduction

How to Downsize a Transport Network: The Chinese Wheelbarrow

Medieval Smokestacks: Fossil Fuels in Pre-industrial Times

The Bright Future of Solar Thermal Powered Factories

The Short History of Early Pedal Powered Machines

Pedal Powered Farms and Factories: The Forgotten Future of the Stationary Bicycle

Bike Powered Electricity Generators are Not Sustainable

Insulation: First the Body, Then the Home

Aerial Ropeways: Automatic Cargo Transport for a Bargain

Hand Powered Drilling Tools and Machines

Boat Mills: Water Powered, Floating Factories

Recycling Animal and Human Dung is the Key to Sustainable Farming

The Status Quo of Electric Cars: Better Batteries, Same Range

The Sky is the Limit: Human-Powered Cranes and Lifting Devices

Wood Gas Vehicles: Firewood in the Fuel Tank

Gas Bag Vehicles

Trolley Canal Boats

How (not) to Resolve the Energy Crisis

Rings of Fire: Hoffmann Kilns

Wind Powered Factories: History (and Future) of Industrial Windmills

Water Powered Cable Trains

Get Wired (Again): Trolleybuses and Trolleytrucks

Electric Road Trains

The Monster Footprint of Digital Technology

Cargo Ships, Then and Now

Moonlight Towers: Light Pollution in the 1800s

Tiles as a Substitute for Steel: The Art of the Timbrel Vault

A Steam Powered Submarine: The Ictíneo

The Citroën 2CV: Cleantech from the 1940s

Life Without Airplanes: from London to New York in 3 Days and 12 Hours

Bring Back the Horses

Satellite Navigation in the Eighteenth Century

Email in the Eighteenth Century: The Optical Telegraph

Colophon

Introduction

Low-tech Magazine is an online platform refusing to assume that every problem has a high-tech solution. A simple, sensible, but nevertheless controversial message; high-tech has become the idol of industrial societies. By contrast, Low-tech Magazine underscores the potential of past and often forgotten technologies and how they can inform sustainable energy practices.

Sometimes, past technologies can be copied without any changes. More often, interesting possibilities arise when older technology is combined with new knowledge and new materials, or when past concepts and traditional knowledge are applied to modern technology. Inspiration is also to be found in the so-called “developing” world, where resource constraints often lead to inventive, low-tech solutions.

Solar Powered Website

Low-tech Magazine was born in 2007. A website redesign was long overdue so in 2018, I teamed up with Marie Otsuka, Lauren Traugott-Campbell and Roel Roscam Abbing to launch a new publishing platform that abides by low-tech principles. To reduce energy consumption and to make content accessible for readers with old computers and slow internet connections, we opted for a back-to-basics web design. The low-energy website is self-hosted and powered by a small solar panel.

Typical for off-grid renewable power systems, energy storage is limited. This means that the website goes off-line during longer periods of cloudy weather. [1] To compensate for this, we offer several off-line reading options, including a print version of the website. The book you have in your hands contains 32 articles published between 2007 and 2012. The other volume, which was published earlier this year, contains 37 articles published between 2012 and 2018.

About this Book

Whereas the first volume contained all but a handful of web articles published between 2012 and 2018, this second volume features a third of the web articles published in the earlier years, carefully selected for their continued relevance and interest today. Overall, we wanted to make an attractive book with timeless articles rather than an exact copy of the website.

Based on the feedback we received on the first volume, we made a few changes to the design. This volume has more images (263) and they are now located in the middle and not at the end of each article. Furthermore, the images have not been dithered.

For most of the period covered in this volume, I did not make use of footnotes, but rather hyperlinks in the text. For the book, these links have been converted to references, and dead links have been replaced by links to copies of pages recorded by the Internet Archive. Ironically, the references in the book are now more up-to-date than those on the website.

More Books

With the availability of this second book, the most important articles from the first twelve years of Low-tech Magazine are now available on paper. A third volume containing all articles published after September 2018 is anticipated but unconfirmed as yet. We are considering waiting until there is sufficient material to fill another 600-700 pages; alternatively, we could publish more often.

We also plan to bring out a print version of No Tech Magazine, Low-tech Magazine’s sister blog that has been curating shorter posts since 2009. But for now, the focus is back on writing.

Thanks

As a final note, I thank my readers for their continued support. This volume was only made possible because you bought enough copies of the other volume, and because you have sent generous donations. I also thank Laia Comellas, Adriana Parra and Kathy Vanhout for their work and patience in making this second book. Self-publishing rocks, but it’s not easy. ←

Kris De Decker

November 2019

1: solar.lowtechmagazine.com/about.html

2: https://www.lowtechmagazine.com/how-to-recognize-a-badly-printed-lulu-book.html

How to Downsize a Transport Network: The Chinese Wheelbarrow

For being such a seemingly ordinary vehicle, the wheelbarrow has a surprisingly exciting history. This is especially true in the East, where it became a universal means of transportation for both passengers and goods, even over long distances.

The Chinese wheelbarrow – which was driven by human labour, beasts of burden and wind power – was of a different design than its European counterpart. By placing a large wheel in the middle of the vehicle instead of a smaller wheel in front, one could carry three to six times as much weight than if using a European wheelbarrow.

The one-wheeled vehicle appeared around the time the extensive Ancient Chinese road infrastructure began to disintegrate. Instead of holding on to carts, wagons and wide paved roads, the Chinese turned their focus to a much more easily maintainable network of narrow paths designed for wheelbarrows. The Europeans, faced with similar problems at the time, did not adapt and subsequently lost the option of smooth land transportation for almost one thousand years.

Transport Options over Land

Before the arrival of the steam engine, people have always preferred to move cargo over water instead of over land, because it takes much less effort to do so. But whenever this was not possible, there remained essentially three options for transporting goods: carrying them (using aids like a yoke, or none at all), tying them to pack animals (donkeys, mules, horses, camels, goats), or loading them onto a wheeled cart or wagon (which could be pulled by humans or animals).

Carrying stuff was the easiest way to go; there was no need to build roads or vehicles, nor to feed animals. But humans can carry no more than twenty-five to forty kg over long distances, which made this a labour-intensive method if many goods had to be transported. Pack animals can take about 50 to 150 kg, but they have to be fed, are slightly more demanding than people in terms of terrain, and they can be stubborn. Pack animals also require one or more people to guide them.

When carrying goods – whether by person or by pack animals – the load is not only moved in the desired direction but it also undergoes an up and down movement with every step. This is a significant waste of energy, especially when transporting heavy goods over long distances. Dragging stuff does not have this drawback, but in that case you have friction to fight. Pulling a wheeled vehicle is therefore the most energy-efficient choice, because the cargo only undergoes a horizontal motion and friction is largely overcome by the wheels. Wheeled carts and wagons, whether powered by animals or people, can take more weight for the same energy input, but this advantage comes at a price; you need to build fairly smooth and level roads, and you need to build a vehicle. If the vehicle is drawn by an animal, the animal needs to be fed.

When all these factors are taken into consideration, the wheelbarrow could be considered the most efficient transport option over land, prior to the Industrial Revolution. It could take a load similar to that of a pack animal, yet it was powered by human labour and not prone to disobedience. Compared to a two-wheeled cart or a four-wheeled wagon, a wheelbarrow was much cheaper to build because wheel construction was a labour-intensive job. Although the wheelbarrow required a road, a very narrow path (about as wide as the wheel) sufficed, and it could be bumpy. The two handles gave an intimacy of control that made the wheelbarrow very manoeuvrable.

East and West: a Very Different Story

The wheelbarrow tells a very distinct history in both the Western and the Eastern world. Although to this date its origins remain obscure, it is clear that the vehicle played a much larger role in the East than in the West. While in recent years there has surfaced some evidence that the wheelbarrow might have been used on construction sites by the Ancient Greeks at the end of the fifth century BC, there is no mention at all of wheelbarrows in Ancient Rome (although that does not exclude the possibility that they in fact did use them).

The first sound evidence of the wheelbarrow in the Western world only emerged in the early thirteenth century AD. In China, their use is documented extensively from the second century AD onwards – more than a thousand years earlier. It is interesting to note that the wheelbarrow appeared at least 2,000 years later than two-wheeled carts and four-wheeled wagons.

Handbarrow

When the wheelbarrow finally caught on in Europe, it was used for short distance cargo transport only, notably in construction, mining and agriculture. It was not a road vehicle. In the East, however, the wheelbarrow was also applied to medium and long distance travel, carrying both cargo and passengers. This use – which had no Western counterpart – was only possible because of a difference in the design of the Chinese vehicle. The Western wheelbarrow was very ill-adapted to carry heavy weights over longer distances, whereas the Chinese design excelled at it.

On the European wheelbarrow the wheel was (and is) invariably placed at the furthest forward end of the barrow, so that the weight of the burden is equally distributed between the wheel and the man pushing it. In fact, the wheel substitutes for the front man of the handbarrow or stretcher, the carrying tool that was replaced by the wheelbarrow.

Superior Chinese Design

In the characteristic Chinese design a much larger wheel was (and is) placed in the middle of the wheelbarrow, so that it takes the full weight of the burden with the human operator only guiding the vehicle. In fact, in this design the wheel substitutes for a pack animal. In other words, when the load is one hundred kg, the operator of a European wheelbarrow carries a load of fifty kg while the operator of a Chinese wheelbarrow carries nothing. He (or she) only has to push or pull, and steer.

The result was an extremely powerful and agile vehicle. In 1176 AD, the Chinese writer Tsêng Min-Hsing noted enthusiastically:

The device is so efficient that it can take the place of three men; moreover, it is safe and steady when passing along dangerous places (cliff paths, etcetera). Ways which are as winding as the bowels of a sheep will not defeat it.

The Chinese wheelbarrow – which was also widely in use in present-day Cambodia, Vietnam and Laos – originally appeared in two basic variants. One was originally termed the “wooden ox” (mu niu), which had the shafts projecting in front (so that it was pulled), while the other was termed the “gliding horse” (liu ma), which has the shafts projecting behind (so that it was pushed). A combination of both types was also used, being pulled and pushed by two men. From these two basic types, many variations evolved. Later, the Chinese also used western-style wheelbarrows alongside their own design.

Western Praise

The characteristic vehicle stupefied Western foreigners who visited China during the early modern period. In Science and civilization in China, Joseph Needham quotes the Dutch-American merchant Andreas Everardus van Braam Houckgeest, who visited the country in 1797 and gives an excellent description of the contraption:

Among the carriages employed in this country is a wheelbarrow, singularly constructed, and employed alike for the conveyance of persons and goods. According as it is more or less heavy loaded, it is directed by one or two persons, the one dragging it after him, while the other pushes it forward by the shafts. The wheel, which is very large in proportion to the barrow, is placed in the centre of the part on which the load is laid, so that the whole weight bears upon the axle, and the barrow men support no part of it, but serve merely to move it forward, and keep it in equilibrum.

The wheel is as it were cased up in a frame made of laths, and covered over with a thin plank, four or five inches wide. On each side of the barrow is a projection, on which the goods are put, or which serves as a seat for the passengers. A Chinese traveller sits on one side, and thus serves to counter-balance his baggage, which is placed on the other. If his bagage is heavier than himself, it is balanced equally on the two sides, and he seats himself on the board over the wheel, the barrow being purposely contrived to suit such occasions.

The sight of this wheelbarrow thus loaded, was entirely new to me. I could not help remarking its singularity, at the same time that I admired the simplicity of the invention. I even think, that in many cases such a barrow would be found much superior to ours.

Wheelbarrow Trains

The American soil scientist F.H. King shows himself equally impressed in his 1911 publication Farmers of Forty Centuries:

We had observed long processions of wheelbarrow men moving from the canals through the streets carrying large loads of [crops] in bundles a foot long and five inches in diameter. These had come from the country on boats each carrying tons of the succulent leaves and stems. We had counted as many as fifty wheelbarrow men passing a given point on the street in quick succession, each carrying 300 to 500 pounds of [crops] and moving so rapidly that it was not easy to keep pace with them, as we learned in following one of the trains during twenty minutes to its destination. During this time not a man in the train haltened or slackened his pace. This same type of vehicle, too, is one of the common means of transporting people, especially Chinese women, and four, six and even eight may be seen riding together, propelled by a single wheelbarrow man.

Rudolf Hommel, in his 1937 book China at work (based on a 1921 travel through the country), seems to be most intrigued by the ingenuity of the low-tech design, going into technical details:

While there are many kinds of wheelbarrows, is typical of them all; the principle always being the same, i.e. one large wheel surrounded by a framework, guarding the upper part of the wheel from contact with merchandise or persons transported. The two long shafts, held at a proper distance from each other by two crosspieces, terminate in the handlebars, and form the basis of the whole vehicle. Into them is mortised the lattice work which surrounds the wheel. On each side a carrying frame is formed by curved bars attached to the main shafts by crosspieces.

The wheel, about 3 feet in diameter, is made entirely of wood and has two iron bands around the hub, and an iron tire. The axle is made of some very strong wood. From the frame of the wheelbarrow two pieces extend downward with the bearing holes for the axle. This looks rather precarious, and yet these pieces stand up splendidly under the heavy strain of immense loads and the considerable bumping over the miserable roads. These wheelbarrows are masterpieces of joinery and special care is bestowed on the selection of the best grades of hard wood for all parts. This description would not be complete without mentioning the squeaking of the unoiled axle, a nightmare to foreigners, which does not bother the Chinese in the least.

Just as other Western observers, Hommel watched the vehicles pass by in admiration:

Besides transporting goods with these wheelbarrows, the Chinese use them also for passengers. I have seen as many as six people on them, three sitting on each side with their feet dangling down. If only one person is conveyed the driver balances the wheelbarrow skilfully with the wheel tilted at a considerable angle from the vertical. If a peasant wants to take a pig to the market, he saves himself all the trouble of guiding the recalcitrant beast, by tying it upon the wheelbarrow and wheeling it to the market.

Mobile Forts

As so many other innovative technologies, the Chinese wheelbarrow was orginally developed for military purposes. The first records mention its use for supplying food to the army. The wheelbarrow gave the Chinese armies such an advantage in moving goods that it was kept secret – early Chinese writings talk about wheelbarrows in code. True to its origin, the wheelbarrow remained in use for military operations, though not only to supply food to soldiers. In 1176, Tsêng Min-Hsing alluded to the military use of the wheelbarrow in forming protective layers. His words are quoted by Joseph Needham:

Not only is it useful for transporting army rations, but at need it can be employed as a defensive obstruction against cavalry. Since the digging of trenches and moats, and the building of forts, take time, the wheelbarrows can be deployed round the perimeter so that the enemy’s horses cannot easily pass over. This kind of vehicle can readily go forward and withdraw, and can be used for any purpose. It might well be called a ‘mobile fort’.

According to Needham, it was the Chinese with their wheelbarrows who pioneered the use of ‘laagers’ or ‘mobile forts’ as a defence against the onslaught of cavalry, a tactical system that remained in use during later times using two-wheeled carts.

Animal Traction

A remarkable feature of the Chinese wheelbarrow was the combined use of human and animal traction, which became common from an early date on. This practice can be seen in a 1126 painting by Chang Tsê-Tuan, which is described by Joseph Needham:

The painting depicts the popular life of the capital Khaifêng at the time of the spring festival. Many wheelbarrows are moving or stationary in the streets of the city. All but one have the large central wheel and some are very heavily laden. During the loading and unloading the wheelbarrows rest on the side-legs. One is being pushed by a single man, and in all cases the porter steadies the vehicle by the shafts behind, while traction is effected either by one man in shafts and one mule or donkey with collar-harness and traces, or by two animals side by side similarly attached.

The latter configuration is shown again in a picture in the Thien Kung Khai Wu (1637), where in the text we read:

The northern one-wheeled barrow (tu yuan chhê) is pushed by one man from behind, with (one or more) donkeys pulling it from the front; it is hired by those who dislike riding (on horseback). The travellers sit on opposite sides to balance it, and a mat roof shields them from sun and wind. This kind of conveyance goes as far north as Chhang-an and Chi-ning, and also comes to the capital. When not carrying passengers these barrows will take as much as four or five tan of goods about six cwt or three hundred kg. The one-wheeled barrow (tu lun thui chhe) of the south is also pushed by one man (but without animal aid), and carries only 2 tan. When it meets pot-holes (in the road) it has to stop; in any case it seldom goes more than one hundred li (50 km).

Wind Powered Wheelbarrows

An even more surprising method to augment human power in moving the wheelbarrow was the use of sails. The date of the introduction of the sailing wheelbarrow is unknown, but Joseph Needham notes that this contraption (the chia fan chhê) was still widely used in China at the time of writing (1965), notably in Honan and in the coastal provinces such as Shantung. Rudolf Hommel and F.H. King also spotted and described the vehicles. While some sails were very simple pieces of cloth, others were perfect miniatures of the ones used on a junk (a Chinese sailboat), easily adjustable by the driver.

The use of auxiliary power from animals and wind (the two were sometimes combined) made it possible to design larger wheelbarrows that could take more cargo. Again, it is worthy to quote Andreas Everardus van Braam Houckgeest, writing in 1797:

Near the southern border of Shantung one finds a kind of wheelbarrow much larger than that which I have been describing, and drawn by a horse or a mule. But judge of my surprise when today I saw a whole fleet of wheelbarrows of the same size. I say, with deliberation, a fleet, for each of them had a sail, mounted on a small mast exactly fixed in a socket arranged at the forward end of the barrow.

The sail, made of matting, or more often of cloth, is five or six feet (1.5 to 2 m) high, and three or four feet broad, with stays, sheets, and halyards, just as on a Chinese ship. The sheets join the shafts of the wheelbarrow and can thus be manipulated by the man in charge.

One had to grant the apparatus was not a freak, but an arrangement by which, with a favourable wind, the wheelbarrow porters could be greatly assisted. Otherwise such a complicated thing would have been only a bizarre curiosity. I could not help admiring the combination, and was filled with sincere pleasure in seeing twenty or so of these sailing-wheelbarrows setting their course one behind the other.

Wheelbarrows on Rails

The Chinese wheelbarrow kept evolving even after the arrival of the Industrial Revolution, adapting modern materials and wheels. Another noteworthy example of this is the so-called piepkar, which showed up on the island of Billiton at the coast of Sumatra at the turn of the twentieth century. There, a Dutch tin mining company was faced with very bad roads. The solution? A great example of combining Eastern and Western knowledge; wheelbarrows equipped with very narrow wheels, guided by iron rails. The technology – which was in use from the 1880s to around 1920 – reminds of the horse-drawn rail cars that became popular in Western cities at the time.

The Decay of the Chinese Road Infrastructure

The importance of the Chinese wheelbarrow can only be understood in the context of the Chinese transportation network. Prior to the third century AD, China had an extensive and well-maintained road network suited for animal powered carts and wagons. It was only surpassed in length by the Ancient Roman road network. The Chinese road infrastructure attained a total length of about 25,000 miles (40,000 km), compared to almost 50,000 miles (80,000 km) for the Roman system.

The Chinese and Roman road systems were built (independently) over the course of five centuries during the same period in history. Curiously, due to (unrelated) political reasons, both systems also started to disintegrate side by side from the third century AD onwards, and herein lies the explanation for the success of the Chinese wheelbarrow. As we have seen, the one-wheeled vehicle appeared during this period, and this is no coincidence. Increasingly, it was the only vehicle that could be operated on the deteriorating road network. As F.H. King observed: “For adaptability to the worst road conditions no vehicle equals the wheelbarrow, progressing by one wheel and two feet”.

In 1937, Rudolf Hommel goes on complaining about the Chinese roads:

In olden times, excellent wide roads were in existence in China, suitable for chariots, coaches, and wagons of many descriptions. Present-day conditions show a different picture, especially in Southern and Central China where the two-wheeled cart is not known. The splendid roads are gone, and in their place, we find only narrow paths, scarcely wide enough for foot passengers and wheelbarrows. The two-wheeled cart survived only in North China under the sway of the court of Peking, where the important business of victualizing the capital was sufficient urge to keep up the roads.

The Chinese peasant, ever intent to gain more ground for the cultivation of his crops, has gradually reduced the width of former highways, unhampered by a watchful government. In fact, the greedy officials winked at such encroachments, as long as they have been thereby enabled to exact increased contributions in taxes from the hardworking peasants. It is only within the last five years that an extensive program of road building has been carried out.

Pathways Designed for Wheelbarrows

However, it seems that Rudolf Hommel got it wrong, and was looking at the Chinese roads with a Western bias. Joseph Needham tells a more positive story, noting that the network of wide roads was gradually replaced by an informal, low-tech infrastructure that was not less ingenious than the wheelbarrows that operated on it. The Chinese answer to a decaying road infrastructure went much further than the adaptation of their vehicles:

In many periods the government was interested primarily, and sometimes exclusively, in those roads and water-ways which were significant for tax-grain transportation and the conveyance of official messages. The upkeep of a multitude of local roads and paved pathways devolved, therefore, upon the people themselves, acting in their co-operative capacity under village elders and small-town worthies. In this context, religious associations, such as the Taoists Yellow Turbans about 180 AD, later so politically important, or the Buddhist fraternities afterwards, played a significant part. Making good roads was nothing less than a pious duty.

Thus in the course of time, quite apart from the Ancient and medieval imperial highways, China’s landscape became shot through with millions of miles of well-paved paths, suitable chiefly for pedestrians, porters with carrying poles, pushers of wheelbarrows, and men carrying litters. Rough unpaved cart-tracks predominated only in the Eastern plains. Those who, like the author, have followed these paved ways past woods and rice fields for many a mile cannot think of them without intense nostalgia. There was a long tradition of such privately initiated roads going back to the Han or even earlier, and their total mileage far outstripped that of the government main roads as the ages passed.

Interestingly, the modern, twentieth-century road network that appeared in China, and that Hommel was alluding to in 1937, did not immediately gave way to the automobile, but to another low-tech vehicle that is a worthy competitor for the wheelbarrow: the bicycle, a product of the Industrial Revolution that is even more efficient. It will probably take us (and the 21st-century Chinese) another few decades before we realise how smart the Chinese transport infrastructure was.

The Decay of the Western Road Infrastructure

The use of wheelbarrows in combination with specially designed narrow pathways made land transportation in China considerably more efficient than in Europe for a period of almost 1,500 years. Today, critcism on the omnipresent automobile is often ridiculed by saying that we cannot go back to horses and carts, without realizing that the combination of horses and carts is far from evident and not as low-tech as it seems. History clearly shows that an extensive road infrastructure is a very vulnerable thing.

Europe was also left with a deteriorating road network after the demise of the Roman Empire, though the Europeans could buy some time. Because it was sturdier (using piles of stone and concrete rather than the early form of asphalt applied by the Chinese), the Roman road infrastructure remained relatively useful until about the eleventh century AD, after which it was largely abandoned. But even before that time, the destruction of bridges and road facilities by the barbarians – or by the locals in order to defend themselves against the barbarians – gradually dimished its usefulness. Lack of maintenance and the plundering of paving stone did the rest. Moreover, the appearance of new towns and capitals (such as Paris) required new routes that did not always coincide with the existing Roman roads.

Contrary to the Chinese, the Europeans did not develop a new vehicle and appropriate infrastructure of paths to make up for the loss of the Ancient highways. New roads appeared during the economic revival of the late Middle Ages, but these were not paved or hardened in any other way. This made them at best inefficient in good weather and nearly impassable when (and after) it rained. Furthermore, because of the absence of foundations, soil erosion caused by heavy rains could wash entire roads away. As a result, the use of carts and wagons all but disappeared in medieval Europe, while nothing else came in place. For people, the options of land transportation again became limited to walking or – only for the rich – horseback riding.

Cargo was most often transported by pack animals (mostly donkeys and mules, sometimes horses), or simply by carrying it. With the exception of England, where wheeled traffic resurged from as early as the 14th century in some places, and France, where some sturdier roads (unpaved but with foundations) appeared in some regions during the late 16th century, smooth operating wheeled traffic only made a comeback in Europe during the nineteenth century – at the same time as the first railroads appeared.

Ox Drawn Carts

Carts and wagons drawn by oxen remained in use throughout the centuries in Europe, for heavy or large-sized loads that could not be transported by rivers or by sea. However, road conditions often required large spans of oxen, which made wheeled transportation of heavy loads ridiculously expensive and limited to very short distances. Because of friction, the nature of a road surface greatly determines how efficient wheeled transport will be. In Energy in world history, Vaclac Smil writes:

On a smooth, hard, dry road, a force of only about thirty kg is needed to wheel a one tonne load. A loose, gravelly surface may easily call for five times as much draft. On sandy or muddy roads the multiple can be seven to ten times higher.

This had important consequences. Many countries could not capitalize on most of their energy resources, be it wood or peat or coal, because transporting them over land took more time and energy (in terms of animal feed) than they could afford. If they would have been aware of the Chinese wheelbarrow, the Europeans could have followed a similar strategy as the Chinese, using their limited resources to construct and maintain smooth but narrow pathways (and bridges) while downsizing their vehicles. As was noted in several of the historical sources mentioned above, the Chinese wheelbarrow, aided by a second man, an animal, or wind power, could transport up to three hundred kg of cargo. This was almost as much as the maximum allowed cargo for horse and ox drawn carts in Ancient Rome (326 kg and 490 kg respectively).

Lessons for the Future

Of course, it was not only the wheelbarrow that kept Chinese communication running after the second century AD. At least as important was the impressive network of artificial canals that complemented it. This infrastructure became ever more important after the detoriation of road network. For example, the Grand Canal, which ran from Hangzhou to Bejing over a distance of 1800 km, was completed in 1327 after seven hundred years of digging.

In Europe, the first (relatively modest) canals were only built during the sixteenth century, and most of them only appeared in the eighteenth and nineteenth centuries. The Chinese wheelbarrow alone could not have given Europe an equally effective transport infrastructure as the Chinese, but there is no doubt that it could have made life in medieval Europe a great deal easier.

The story of the Chinese wheelbarrow also teaches us an obvious lesson for the future. While many of us today are not even prepared to change their limousine for a small car, let alone their automobile for a bicycle, we forget that neither one of these vehicles can function without suited roads. Building and maintaining roads is very hard work, and history shows that it is far from evident to keep up with it.

In this regard, it is important to keep in mind that we won’t be as lucky as the medieval Europeans who inherited one of the best and most durable road networks in the world. Our road infrastructure – mostly based on asphalt – is more similar to that of the Ancient Chinese and will disintegrate at a much faster rate if we lose our ability to maintain it. The Chinese wheelbarrow might one day come in very handy again. ←

A Chinese wheelbarrow in Shanghai, 1910. Institut d’Asie Orientale / Lyon Institute of East Asian Studies.

“Honey Wagon” for the transport of human waste. China, Beijing, 1917-1919. (Photo by Sidney David Gamble).

The Chinese wheelbarrow was used to transport people and cargo. Image from 1880. Institut d’Asie Orientale / Lyon Institute of East Asian Studies.

Urban transportation by wheelbarrow, 1907. University of Bristol - Historical Photographs of China, reference number: Bk05-02. From the book ‘Shanghai’ (published by Max Nössler, c.1907).

Wheelbarrow with pig and smoking passenger, on their way to the market, Shanghai, 1897. Edward Bangs Drew.

Wheelbarrows with sails in China. Казанин М.И. Очерк экономической географии Китая./М. ОГИЗ.Соцэкгиз, 1935 – С.106.

Wheelbarrows with sails, near Xi’an, China, c.1905. John Shields.

Sail wheelbarrow in Shandong province, 1928. National Archives and Record Administration (NARA).

A Chinese wheelbarrow equipped with sails. Public domain.

A Chinese wheelbarrow, pushed by a man and pulled by a donkey. Old Postcard.

Application of wheelbarrows during flood control projects, Shandong, before 1973. Jinian Mao zhuxi ‘Yiding yao genzhi Haihe’ tici shi zhou nian yingji 1963-1973 : 60/61, 118. Translation: “Collection of Photos from 1963 to 1973 in Commemoration of the Tenth Anniversary of Mao Zedong’s Slogan ‘We Must Control the Rivers and Seas’.”

References

Needham, Joseph (1965). Science and Civilisation in China, Vol. 4: Physics and Physical Technology, Part 2: Mechanical Engineering. Cambridge: Cambridge University Press.

Needham, Joseph (1971). “Wheels ex-aqueous and ad-aqueous; ship-mill and paddle-boat in east and west”, in Needham, Joseph (1971). Science and Civilisation in China, Vol. 4: Physics and Physical Technology, Part 3: Civil Engineering and Nautics. Cambridge: Cambridge University Press.

Hommel, Rudolf P., & Volunteers in Asia, inc. (1937). China at work: An illustrated record of the primitive industries of China’s masses, whose life is toil, and thus an account of Chinese civilization. Cambridge, Mass: M.I.T. Press.

Song, Yingxing, & Li, Qiaoping (1980). Dian’gonggaiwu = Exploitation of the work of nature: Chinese agriculture and technology [i.e. technology] in the XVII century. Taipei, Taiwan, Republic of China: China Academy.

King, Francis Henry (1911). Farmers of forty centuries; or, permanent agriculture in China, Korea and Japan. Madison, Wisc: Author.

Matthies, Andrea L. (1991). “The medieval wheelbarrow”, Technology and Culture, Vol. 32, No. 2, April 1991.

Lewis, M. J. T. (1994). “The origins of the wheelbarrow”, Technology and Culture, Vol. 35, No. 3, July 1994.

Rockwell, Alfred Perkins (1896). Roads and pavements in France. NewYork: Wiley.

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Langdon, John (1984). “Horse hauling: a revolution in vehicle transport in twelfth- and thirteenth-century England” in Aston, T. H. (ed.) (1987). Landlords, Peasants and Politics in Medieval England. Cambridge: Cambridge University Press.

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Michael Markowski (translator) (s.d.) “Medieval Sourcebook: Richer of Rheims: Journey to Chartres, 10th Century”, on Halsall, Paul. Fordham University (website, 1996)

Part of the Internet History Sourcebooks Project at Fordham University, New York.

Willard, James F. (1926). Inland transportation in England during the fourteenth century. Cambridge: Harvard University Press.

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Based on Temple, R., The Genius of China. New York: Touchstone Books, Simon and Schuster, 1989, pp. 84-86, 195-196.

Medieval Smokestacks: Fossil Fuels in Pre-industrial Times

Almost all of the leading economies in Western Europe during the last millenium relied on a large-scale use of fossil fuels such as peat and coal.

The history of energy use in human civilisation is generally summarised as follows: from Antiquity until the start of the Industrial Revolution, people made use of the manual labour of both animals and humans, as well as biomass, sun, water and wind. Next, all these renewable energy sources were replaced by fossil fuels: first coal, and later oil and gas. Uranium completed the picture in the second half of the twentieth century. While this historical summary is basically correct, there were some – rather important – exceptions. Almost all of the leading economies in Western Europe during the last millenium relied on a large-scale use of fossil fuels such as peat and coal.

Thermal Energy

Before we delve into the pre-industrial history of fossil fuels, it is important to note the difference between thermal energy (heat) and kinetic energy (motion). For the greater part of history, wind, water and muscle power could provide only kinetic energy. This was the kind of energy required to grind grain, saw wood, or set sailboats in motion. For centuries, wood (and charcoal made of wood) was the only source of thermal energy in Europe, apart from the use of direct solar energy for low-temperature processes like the drying of mud bricks and food crops. Wood or charcoal were required for activities such as heating buildings, cooking food, producing building materials (such as bricks, tile, cement, lime and plaster), manufacturing glass and paper, forging iron or producing dyes and soaps. At the same time, wood was the main construction material for buildings, ships, bridges, mills, piers, wharves, cranes, winches, mine shafts, vehicles, barrels, furniture and tools.

The invention of the steam engine in the eighteenth century meant that thermal energy could be converted into kinetic energy: the heat generated by the burning of coal was used to power machines and vehicles. Likewise, the arrival of electricity in the 19th century allowed kinetic energy to be converted into thermal energy: a windmill, for instance, could be used to drive a generator that delivers energy to an electric oven, or heater. (Kinetic energy could produce heat by friction, for example in windmill gears, but this was mostly wasted). These days, it is self-evident that both types of energy can be converted to one another (with considerable efficiency losses), but for most of human history kinetic energy and heat energy were entirely different and were treated separately. Then, just as now, thermal energy was much more important than kinetic energy.

Urban Revival

The Romans – who fuelled much of their mechanical activities with slave labour – deforested large parts of Europe in their hunger for thermal energy and construction materials. When their empire collapsed, forests recovered during the half millenium that is termed the Dark Ages. At the beginning of the second millenium AD, Europe became the setting of an urban revival. Between 500 and 1000 AD, some important agricultural innovations occured, including improved ploughs, the triennal rotation of crops, the horse collar, and the horse shoe.

These technologies enabled a larger population and higher food surplus: more food could be supplied with less labour, which further aided the growth of cities in which people could do things other than working the land. The invention of the printing press, for example, further increased the demand for wood. Similarly, building gothic cathedrals required tonnes of materials, raising thermal energy use.

Urbanisation thus went hand in hand with increased industrial acitivity. Also, medieval industrial processes were less efficient than similar processes today. For example: up to twenty kg of charcoal (with an energy content of 600 MJ) was used to produce one kg of iron (compared to 20-25 MJ/kg today). Urbanisation and industrialisation increased rapidly between 1100 and 1300, which again resulted in widespread deforestation.

Not a Paradise

Our romantic image of the Middle Ages and Renaissance as a paradise of renewable technologies results largely because of our failure to distinguish between thermal and kinetic energy. The Dutch and the Flemish, who dominated the Western European economy from about 1100 to 1700, are famous for their impressive use of wind technology, which took off in the 1100s. The most spectacular use of windmills appeared in Holland from the late 1500s (sixteenth century) onwards. There, the Dutch applied wind power to a wide range of industrial processes, including paper production, wood sawing, glass polishing and cement production.

The industrial windmill was a marvel of pre-industrial technology, but it explains only partly why Holland became the most important economic power in the world during the seventeenth century. While sustainable providers of power, windmills could only deliver kinetic energy. To give just one example: you can use wind power to polish glass, but you can’t make glass using a windmill. For that, you need thermal energy. And in pre-industrial times, as the history books tell us, the only way to reach high temperatures was to burn wood. One problem, though: virtually all forests in the region had long vanished by the 1600s. Yet, during the Golden Age of the Netherlands, the Dutch not only made glass, they also produced bricks, tiles, ceramics and clay pipes, they refined salt and sugar, bleached linen, boiled soap, brewed beer, distilled spirits and baked bread. All these processes were based on a massive input of thermal energy.

Moreover, the Dutch produced much more than needed for domestic consumption. They became the largest European exporters of many of the above-mentioned industrially manufactured products. On a more modest scale, a similar production boom had happened in Flanders a few centuries earlier, in which an energy-intensive industry appeared in the near total absence of wood reserves. So how did the Dutch and the Flemish achieve this? By mining peat on a truly massive scale.

What is Peat?

An intermediate step in the formation of coal, peat forms when plant material, usually in marshy areas, does not decay fully because of a lack of oxygen. This semicarbonised fuel can be found near the earth’s surface in layers of up to five metres thick. The energy density of dried and pressed peat – known as turf – is about 15 to 17 MJ per kg, which is similar to the energy density of dried wood (15 to 18 MJ/kg) but lower than that of coal (24 MJ/kg) or charcoal (up to 29 MJ/kg). However, it is a bulkier fuel than wood: one cubic metre of coal provides six times as much heat as one cubic metre of turf, for instance.

Turf is still used today in some countries, notably in Ireland, Finland and Russia, where it is burned in power plants and used for domestic heating. While peat is classified by the IPCC as a renewable fuel, this is highly debatable. Peat is renewed at a rate of about 1 mm per year at most, and so it takes at least 3000 years for a peat layer of 3 m to return to its original size – and only if the land is not disturbed in that time. In addition, the mining of peat has a very large impact on the landscape, while the burning of turf produces slightly more CO2-emissions than coal for the same energy content. The only advantage it has over coal is that it produces less smoke and has a lower sulfur content, and thus produces less air pollution than coal.

How to Dig Peat

In pre-industrial times, peat was dug out using very simple tools. Before being cut, the peat was often partially dehydrated by digging drainage trenches on its surface. Next, the land was stripped of its vegetation and the peat sods were cut up vertically to the required size. The following step was to cut out the peat sods horizontally, after which they were loaded onto wheelbarrows and transported to a nearby field. There, they were laid out or stacked up vertically in a formation for drying. It took six to eight weeks for the peat sods to become dry enough to be used as fuel, after which they were beaten or trodden to make them more compact. During the drying process in the field, the peat sods were turned regularly. Finally, the peat (now called turf) was loaded in baskets and carried to the farm or the market.

Mining peat was a seasonal activity that took about three months per year, from late spring to early summer. Starting production earlier than April was risky because frost could damage the drying peat. Digging peat in summer was equally risky because there was a chance that it would not be dry enough following a cold and wet season. Likewise, a very hot summer could make the peat useless if it was not taken away from the drying field quickly enough – it would then be dispersed by the wind. You could thus argue that peat has the disadvantages of both a fossil fuel and a renewable fuel, without any of the benefits. Like other better known fossil fuels, it is a non-renewable energy source that produces large amounts of CO2, yet it has an energy density that is much lower than other fossil fuels. On the other hand, peat digging is a seasonal activity with a “harvest” that may fail because of the weather. And yet, because they had no other choice, the Dutch and the Flemish built their entire economy around it.

The Low Countries

The evolution of peat production was eerily similar to the mining of fossil fuels today. When the easiest accessible reserves were exhausted, the peat diggers developed new technologies and methods to mine harder-to-reach resources at an ever increasing financial and environmental cost. We do not have much detailed knowledge about peat production in Flanders and Brabant, because few written records from the late Middle Ages remain. However, the history of peat production in the present-day Netherlands is relatively well documented.

The urban revival of the late Middle Ages started in Northern Italy, where the dominating merchant cities were Venice, Milan, Genoa and Florence. However, around 1100 a second urban core developed east of the North Sea, a region that would become known as the “Low Countries” from the fifteenth century onwards. This region would soon rival the economic power of the Italian cities, and become the leading economic and industrial centre in Europe from about 1500 to 1700. The cities of Bruges, Ghent and Ypres in the province of Flanders (today a portion of Belgium) were the first to develop. Bruges, in particular, became an economic powerhouse due to its position in international trade, finance and cloth production. In 1350, Bruges and Ghent boasted a population of 90,000 and 57,000 inhabitants respectively (compared to 1,000 in Amsterdam, for instance).

Around 1500, economic power shifted to the cities of Antwerp, Brussels and Leuven (today all in Belgium) in the province of Brabant. Antwerp became the economic centre of the Western world, a position it would maintain until the end of the 1500s (sixteenth century). By 1550, Antwerp had 90,000 inhabitants, up from 40,000 in 1500, which made it the second largest city in Europe, North of the Alps, after Paris. In 1580, the Low Countries, then under Spanish rule, were divided into two. The seven provinces in the North revolted against the Spanish and formed a new state, the Dutch Republic (the present-day Netherlands). As a result of the subsequent chaos in the Southern provinces (present-day Belgium), the city of Antwerp lost its leading role and power shifted rapidly to the Dutch province of Holland, where the capital of Amsterdam now became the European centre of economic and industrial activity. It would remain so until the end of the 17th century.

The Evolution of Peat Mining

Large-scale peat digging started in the coastal area of Flanders and northeast of Antwerp in the 1100s and 1200s respectively. The activity was largely aimed at supplying the fuel for the fast-growing cities of Bruges, Ghent and Ypres. The reserves in the coastal peat bogs of Flanders were exhausted by the end of the 1300s or 1400s, while peat production in Brabant diminished sharply during the course of the fifteenth century. By the time Antwerp came to dominate the world economy, its peat reserves had already been dug out to satisfy the energy needs of Flanders in the course of the preceding two centuries. As a result, peat digging shifted to the neighbouring province of Holland, from where the turf was exported to Antwerp.

At the time, Holland was still largely an agrarian region with relatively few energy needs. During this period, it is estimated that between 220 and 440 hectares of peat bogs were mined every year in Holland and Utrecht. Around 1530, the then accessible reserves in both provinces became exhausted, while demand continued to grow. As a result, peat prices skyrocketed. In response to this, peat diggers developed a new tool, the baggerbeugel (a dredging net on a long pole, there seems to be no English translation for the term). Standing on a small boat or at the waterside, this tool allowed them to cut peat below water level and haul it up. This technique, called slagturven (again, no English translation available), greatly enlarged mineable peat reserves. The peat bogs in Holland and Utrecht were up to 4.5 metres thick, but because of the high water table in the region (why we call these the “Low Countries”), only the top layer could be stripped away using conventional techniques. Digging deeper would have flooded the land and made the fuel inaccessible.

However, now that it was possible to cut peat far below the water level, the complete peat bogs could be mined. There is evidence that the “baggerbeugel” was already in use in Flanders two centuries earlier, and that the knowledge of the technique was transferred to the North. The intensification of peat production came at a cost, though. To start, mining peat from below the water table introduced extra steps in the processing of the fuel. Due to its increased water content, the muddy peat had to be spread out on narrow and elongated strips of land which were not stripped of their peat. There, the water was pressed out by people trodding on it with boards tied beneath their clogs. Only when this was done, could the peat be cut up in blocks and stacked to dry.

Environmental Costs: Land Turned into Water

Worse, however, was the destruction of the landscape and the loss of agricultural land. Wherever the peat was mined below the water table, land disappeared into the waves. This was a rather ironic consequence for a country that spent so much effort reclaiming land on the sea elsewhere on its territory through the use of windmills. Every year, about 115 to 230 hectares of land was lost as a result of peat production below the water table. The exhausted peat bogs formed lakes that expanded to cover vast areas throughout Holland and Utrecht. Only the elongated strips of land used to dehydrate the muddy peat remained.

Historian Jan de Vries (see references) notes that the area between Amsterdam, Rotterdam and Utrecht “took on the appearance of a veritable Swiss cheese, with dozens of water-filled, exhausted peat bogs often separated from each other by nothing more than narrow vulnerable strips of land on which were scattered the structures of what once had been farms”. Some of these typical lakes still remain, for example the Nieuwkoopse Plassen in Holland, today a nature reserve of 1,400 hectares. Other remaining examples are the Loosdrechtse plassen and Vinkeveense plassen in the province of Utrecht. Often, even the narrow ridges of land used for drying the peat were eventually mined or simply washed away by the waves during storms.

Things got out of hand when entire villages disappeared. Historian J.W. De Zeeuw (see references):

Around 1600, these lakes occupied most of the area between the rivers Oude Rijn, Gouwe and Hollandse Ijssel and threatened the villages of Zevenhuizen, Moerkapelle and Waddinxveen. In 1630, the church of Jacobswoude, North of the Oude Rijn, was pulled down because by then the rest of the village had been swallowed by the waves of encircling man-made lakes.

In the course of the centuries, peat digging caused the fusion of two large lakes (the Haarlemmermeer and the Leidsemeer) and several smaller ones in Holland, forming an inland sea of 17,000 hectares which destroyed several villages (Nieuwerkerk, Rijk, Vijfhuizen, and a part of Aalsmeer). The water body – popularly known as the water wolf - threatened the surrounding cities of Haarlem, Leiden and Amsterdam in the 1800s, after which it was (largely) impoldered. The authorities, horrified by the loss of agricultural land – and the associated tax income – tried to stop the peat diggers during the sixteenth century by placing export prohibitions and restrictions on peat mining below the water table, but they failed. Digging out peat was more lucrative than cultivating crops. In total, peat digging would turn more than 60,000 hectares (600 km2) of land into water in Holland and Utrecht – almost ten percent of their total surface area.

Peat Production Moves to the North: Canal Digging

Again, energy demand rose significantly from the late sixteenth century onwards, when economic power shifted from Flanders and Brabant to Holland. In spite of the environmental damage, peat production in the low peat bogs of Holland and Utrecht continued on a casual basis during the 1600s, with an average production of 200 hectares per year. However, this was not enough to satisfy the growing demand for the fuel, and turf prices started rising again. In response, from the 1580s onwards, attention shifted to the somewhat higher lying peat bogs in the northern provinces of Friesland, Groningen and Drenthe – 200 to 250 kilometres away. There, total production during the seventeenth century would rise to an average of almost 400 hectares per year. Most of the turf was exported to Holland.

However, mining these reserves was a totally different matter because there were few waterways. Transporting the turf all the way to the Zuiderzee, from where it could be shipped to Holland and Utrecht, would have been inordinately expensive given the transport options of the day. In order to exploit the high peat bogs in the Northern provinces, ditches and canals had to be dug, which required a large capital investment. Historian Jan de Vries:

The result was that, instead of the numerous individual peat diggers each working small parcels of laagveen (low bogs), the peat in the hoogveen (high bogs) was mined by consortia of investors (urban capitalists from the western cities) who judged market conditions sufficiently attractive to buy up vast tracts of uninhabited bog, dig lengthy canals into the bogs, and hire armies of laborers to dig the peat.

The extensive canal infrastructure was built in the Northern provinces of the present-day Netherlands from the 1580s onwards. In the high peat regions of Groningen and Eastern Drenthe, canal building continued uninterrupted from 1580 to 1650, which opened up the main body of the peat deposit. This made some 30,000 hectares of peat available for shipping. In the high peat region of Western Drenthe, Friesland and Overijssel, canals were dug between 1600 and 1670 to reach some 30,000 hectares of peat. In total, it is estimated that some 700 km of canals were built in the northern provinces, specifically aimed at turf transport. A substantial amount of them remain, with sometimes surprising results, such as towns without roads (Giethoorn village).

Canal building had happened before in Flanders and Brabant, where the monasteries seem to have been the driving force behind large-scale, organized peat production, buying up land and hiring peat diggers. In the peat bogs in Brabant, Northeast of Antwerp, from about 1300 onwards some twenty turf canals were dug up to sixteen m above sea level, each reaching lengths of ten to twenty km. The main canals, which connected the export harbours with the peat areas, attained a total length of more than 320 km. Aqueducts were built to help the canals cross the brooks. In the Northern provinces of the Netherlands, the total length of the canals reached at least 700 km.

Peat Production and Agriculture

The exploitation of the high peat bogs in the North did not always result in the loss of agricultural land, as it did in the South. Firstly, because the peat mining companies converted some peat bogs into permanently agricultural land after the peat had been dug out. J.W. De Vries:

Once the peat was stripped away, these enterprises had a further interest in making use of the newly exposed underlying soils. Since this soil lay above the water table, the cost of converting it into productive agricultural land consisted primarily of taking the trouble to conserve the surface soil (which was in the case of high peat bogs in any event poor quality peat) so that it could be re-spread over the land, and heavily manuring the new soil. This occurred most systematically in Groningen, where the capital city encouraged agricultural development of the hoogveen by subsidizing the distribution of night soil.

The new canal network created to move the turf to Holland’s industry in the South also provided low-cost transport for agriculture which, by itself, could never have afforded such an investment. However, the efforts to reclaim agricultural land in some parts of the country did not make up for the much larger losses elsewhere on the territory. Few peat bogs in Groningen were brought under cultivation during the Golden Age – it was only with the arrival of artificial fertilizers at the end of the nineteenth century that large-scale recultivation could begin. In the province of Friesland, the underlying soil was not suited for agriculture and peat digging resulted in large lakes which still exist today. And as we have seen, vast tracts of (potential) agricultural land disappeared in the waves in the Southern part of the country. The result is that the Dutch became, unlike other European countries at that time, highly dependent on food imports. They produced vegetables, meat and dairy products, but they had to import about half of their grain (the staple food) from the Baltic regions – a very costly affair.

Energy Consumption per Capita

Until the twentieth century, the Dutch stripped an estimated 283,500 hectares (2,835 square km) of peat, close to 10 percent of the total surface of the Netherlands. However, only two thirds of this was mined in pre-industrial times. Peat digging in the Netherlands continued until 1950 using mechanical peat diggers powered by coal, as it happened in many other countries from the end of the nineteenth century. If we take 1850 as the start of the “modern” peat mining era (the Netherlands were very late to enter the Industrial Revolution), the pre-industrial use of peat in the country amounts to just over 190,000 hectares from about 1300 to 1850. Of this, some 70,000 hectares were mined from 1600 to 1700, which roughly corresponds with the Golden Age of the Netherlands.

All these figures are deduced from a 1978 paper by .W. de Zeeuw, Peat and the Dutch Golden Age. Other authors (like Jan de Vries) give higher estimates in more recent studies, with about 275,000 hectares of peat stripped after 1600. Either way, almost all peat that existed in the Netherlands has been mined. De Zeeuw also calculated the heat content of the extracted peat, taking into account the average thickness of the mined peat layers after dehydration. He concluded that in an average year in the seventeenth century, the Dutch consumed 25,120,800 GJ of turf. With an average population of 1.5 million this amounts to 16.75 GJ per capita per year.

Other authors have come to similar figures, ranging from 13.4 to 19.3 GJ per capita per year. This is similar to dozens of poor countries today, some of which do not even reach 10 GJ per capita. Average energy consumption per capita worldwide was 76.6 GJ in 2008, only 4.5 times higher than in the seventeenth century Netherlands (though the Dutch themselves now consume much more, with 210 GJ/capita in 2003). It should be noted that the figure of 16.75 GJ/capita only includes turf consumption, not other energy sources like wind, animal labour, firewood, charcoal and coal (see further).

Urbanization and Industrialisation in Seventeenth Century Holland

The high energy consumption of the Dutch was an anomaly in seventeenth century Europe. The same goes for their prosperity, and for the level of urbanization and industrialisation in the country. More than sixty percent of Dutch people lived in cities, compared to about ten percent in most other European countries at the end of the seventeenth century. The level of urbanisation in seventeenth century Netherlands was only attained in other European countries at the turn of the twentieth century. A similar development happened in Flanders and Brabant in the 1500s, where over 30 percent of the population lived in cities with more than 10,000 inhabitants. From about 1600 to 1720, the Dutch had the highest per capita income in the world – at least double that of neighbouring countries at the time and about five times higher than that of the poorest countries today.

The opening of the peat bogs in the northern provinces from the 1580s onwards meant that the Dutch had a cheap energy source that was widely available, while most other countries in Europe were entirely dependent on wood – which had become ever more expensive as deforestation advanced. The Netherlands’ ample fuel reserves stimulated the development of various fuel-instensive and export-oriented industries. In several cases, the presence of these industries was solely based on the abundant and cheap supply of thermal energy. This was the case for sugar refinement, for example, which is a purely thermal process. Sugar became the world’s most important commodity in the seventeenth century, and Amsterdam was Europe’s largest sugar refiner by 1650. In 1662, more than half of Europe’s one hundred sugar refineries were located in the Netherlands, all of which processed imported sugar from South America and the Carribean.

Salt refinement too was based solely on a massive input of thermal energy. Salt was indispensable as a preserver of meat, fish and dairy products before electrical refrigeration was available. The Netherlands had 293 salt refineries in 1674, most of them concentrated in Holland and each consuming about 800 tonnes of turf per year. About sixty of these refineries were used for packing herring barrels, another important export. In addition, the city of Haarlem became the bleacher of German linen, another industrial process that was purely built on thermal energy. For all these industries, the iconic Dutch windmills did not offer any direct advantage.

The succes of other industries, however, was based on the combination of turf and wind power. The best example of this lies in the shipping industry. Holland became the leading builder of ships in Europe in the course of the seventeenth century. From 1625 to 1700, the Dutch shipyards produced as many as five hundred seafaring vessels per year, many of them commissioned by foreign powers. The wood used to build the ships was sawn using sophisticated wind powered saw mills invented in 1596, while peat provided thermal energy for many shipbuilding processes, such as bending planks, melting tar and forging iron fittings.

Apart from that, peat offered an important indirect advantage. While a large scale use of peat did not prevent the Dutch from importing large amounts of wood, peat catered to their thermal energy needs, and so all imported wood was almost exclusively used as a construction material. This generated a much higher return on investment than its use as firewood, and made the Dutch less vulnerable to high wood prices. Turf was also the fuel of choice for heating homes and public buildings, and for cooking. Only the very rich used firewood, which was much more expensive but produced less pollution.

Why was Peat Only Used in the Low Countries?

The Low Countries were not the only region that suffered from a severe shortage of wood reserves between 1100 and 1700. In addition, peat was found over large parts of Europe, most notably north of the Alps. Why, then, did other countries not resolve their energy shortages by mining peat? For these pre-industrial countries, the value of energy deposits depended on the cost of transportation rather than the cost of gathering the fuel itself. There exists no period in history when a global, continental or even national shortage of wood occured. The problem was always local, caused by deforestation around urban (and industrial) centers.

Land-based transport – which amounted to carts on bad roads – was extremely slow, labour-intensive and expensive, limiting the practical distance between energy deposits and consumption centres to 20 to 25 km at most. The only exception to this was transport on water, which, in pre-industrial times, was powered by wind or by animal or human labour on towpaths (this was much more efficient than land-based transportation because of low friction resistance). One look at the map of the Low Countries immediately reveals why the region could afford to transport turf over large distances: it is criss-crossed by lakes and rivers. From Groningen and Friesland in the outermost northern part of the present-day Netherlands, one can sail (almost literally) straight to Amsterdam, Utrecht, Rotterdam, and then Antwerp, Brussels, Ghent and Bruges in present-day Belgium. No other region in Europe has such a dense water transport network.

To boot, the region is windy and flat, offering great conditions for sailing – and deforestation only improved these conditions. Importantly, the Low Countries are located near the water table – as were their peat reserves. The digging of navigable canals in the peat areas, and the linking of these canals to the already existing, extensive network of natural waterways was relatively easy. Because these natural waterways gave access to all major cities, the turf could be transported by ship directly from the peat fields to the doorstep of the consumer. Hardly any land-based transportation was involved, and this kept costs low.

In most other countries, peat reserves were located too far above the water table, making the construction of canals much more expensive. Often, cities were too far from potential peat reserves or did not have access to navigable rivers. This explains why large-scale peat digging in other European countries and the US only started at the end of the nineteenth century, when peat could be hauled by steam trains or locally converted to electricity (which is easier to transport).

Coal and the End of the Dutch Golden Age

Peat was not the only fossil fuel used during the second millenium AD in Europe. Coal mining started in the thirteenth century in England, Wales and what is now the French speaking part of Belgium. All over Europe, coal quickly became a wanted fuel for specific industrial processes, particularly for blacksmithing and lime manufacturing. Large-scale coal mining started in the 1400s. In 1430, between 1,600 and 2,000 people worked in the coal industry in Liège (present-day Belgium). From the 1500s onwards, coal was used on an ever increasing scale in London, which was then one of the most populated cities in Europe. There, coal was used industrially, but more often in households for heating and cooking. At the beginning of the 1600s, when the Dutch Golden Age began, coal accounted for three quarters of fuel consumption in London, which caused extensive air pollution. Coal burns much dirtier than wood, which is the reason why it was previously forbidden in England. However, the acute shortage of firewood from the 1500s onwards left the English little other choice than to switch to the abundant fuel. Peat was not an option for the English for many of the reasons mentioned above.

Initially, coal offered significant drawbacks compared to peat, which meant that England’s early use of fossil fuels did not provide a commercial advantage during the seventeenth century. In most production processes, coal could not be used because it came into direct contact with the product, which was then ruined by coal’s impurities – notably sulfur. Only in processes where the product could be separated from the fuel did the substitution of coal for wood cause no problems. Because of its lower sulfur content, peat did not have these limitations. The Dutch could use it for almost all thermal processes in their industries. Over time, however, the English managed to adapt their industrial processes for the use of coal instead of wood and charcoal. With every step they took, the English slowly caught up to the Dutch. A turning point came at the dawn of the eighteenth century when the last – and most important – industrial process was converted to coal: the production of iron.

This last step, made possible by the introduction of cokes or purified coal, marked the start of the Industrial Revolution in the Western world. (It should be noted that the Chinese already developed this process in the 11th century). From then on, the use of iron as a construction material was no longer limited by the supply of wood. Turf, on the other hand, could not deliver the intense heat produced by coal, and hence was not used in iron production, nor to power steam engines. (The Dutch never produced iron, they imported it). Moreover, the caloric value of coal is four times higher than that of turf for a given volume, making it much easier to transport and store than peat. The combination of steam power and iron brought the English the rail system, solving the problem of transporting their fuel supply. The railway also proved faster and more flexible than the canal system.

Exhaustion of the Peat Reserves

Around the same time, the most accessible Dutch peat reserves became exhausted. In addition, there was a growing problem with the silting of the shallow harbours and waterways, increasing the costs of turf transport. More and more sandbanks appeared, over which vessels had to be dragged. A similar thing happened in Bruges a few centuries earlier. The unique geographical conditions of the Low Countries, which made the early large-scale use of fossil fuels possible, eventually became a disadvantage. The depletion of the peat reserves and the difficulties in turf transport led to rising turf prices, until the point at which imported coal became cheaper.

To combat this, Dutch industries switched from peat to coal, whenever they could adapt their production to use the cheaper fuel. English export of coal to Holland rose from 35,200 tonnes in 1700 to 117,900 tonnes in around 1750. The import of coal put Dutch industries at a disadvantage, because the English added tax duties. From the 1700s on, Dutch prosperity began to decline. The import of grain became too expensive, and de-urbanisation set in as more people returned to farming. By 1815, the level of urbanization had fallen back from 83 to 60 percent.

Can we Power a Prosperous Society on Renewable Energy?

Pre-industrial use of coal and peat occured succesively in those parts of Europe that dominated industrial production from the 1100s to the start of the Industrial Revolution. The Flemish, the Dutch and the English, consecutively, became the most prosperous regions in Europe at the very moments when they used the largest amounts of fossil fuels. In other words, all economic success stories of the past millenium are based on an ample supply of fossil fuels – accompanied by serious ecological damage. Moreover, these regions produced many exports, so that countries that did not use fossil fuels also benefitted from their application.

All this does not necessarily mean that a prosperous society cannot be built on hundred percent renewables. We can now transport biomass over larger distances, due to good roads and cost-effective transport options. And I am not referring to motorways and diesel trucks, but to trains, strip roads, trolleytrucks, cargo bicycles and light electric vehicles in flat areas, and aerial ropeways and cable trains in mountainous regions. Furthermore, we now have an additional renewable energy source that could deliver vast amounts of thermal energy: solar thermal power. The merits of solar thermal heat and concentrated solar power have been known for centuries, but the materials and industrial processes for large-scale deployment only became available at the end of the nineteenth century. The same applies to geothermal power, the potential use of which was previously limited because of a lack of materials and technology. ←

Peat fueled glass manufacturing in Dordrecht, the Netherlands, 1700s.

A rolling mill (metalworking). Walzwerk Neustadt-Eberswalde. A painting by Carl Blechen, circa 1830.

Cutting peat.

Cutting peat.

Stacking peat to dry. Nationaal Archief, the Netherlands.

Making peat in an area near Rotterdam. Lines of fresh peat lying to dry. The Netherlands, 1918. Collectie Spaarnestad.

Peat digging under water.

Nieuwkoopse plassen. Jan Arkesteijn, public domain.

A dredging bag. Maritiem Digitaal.

Canal infrastructure for peat digging in the northern provinces of the Netherlands. M.A.W. Gerding, Vier eeuwen turfwinning. De verveningen in Groningen, Friesland Drenthe en Overijssel tussen 1500 en 1950. (dissertatie Wageningen Universiteit, 1995; verschenen als A.A.G. bijdragen 35, ISSN 0511-0726).

Peat transport by barge, ca. 1900.

References

Cornelisse, Charles & Jaco Zuijderduijn (2008). Energiemarkten en energiehandel in Holland in de late middeleeuwen. Hilversum: Historische Vereniging Holland.

Zeeuw, J.W. de & Jan de Vries (1978). Peat and the Dutch Golden Age: the historical meaning of energy – attainability. Wageningen.

Vries, Jan de, & Woude, A. . (1997). The first modern economy: Success, failure, and perseverance of the Dutch economy, 1500-1815. Cambridge: Cambridge University Press.

Vries, Jan de (1976). Economy of Europe in an age of crisis, 1600-1750. Enskede: TPB.

Leenders, K. A. H. W. 2013. Verdwenen venen: een onderzoek naar de ligging en exploitatie van thans verdwenen venen in het gebied tussen Antwerpen, Turnhout, Geertruidenberg en Willemstad 1250-1750. Wageningen: Pudoc, 1989.

English summary by Leenders: http://users.bart.nl/~leenders/txt/boek1989.html

Gerding, Michiel A.W. (s.d.). “Peat and Canals”. Drenthe: (s.p.).

Accessible through https://web.archive.org/web/20111016191216/http://www.newyork
canals.org/_pdfs/Gerding.pdf.

Riet, Arie J. Jan van ‘t (2005). ‘Meeten, boren en besien’: turfwinning in de buitenrijnse ambachten van het Hoogheemraadschap van Rijnland 1680-1800 (dissertation). Hilversum: Verloren.

Lintsen, Harry (1993). Geschiedenis van de techniek in Nederland: de wording van een moderne samenleving 1800-1890. Deel IV: Delfstoffen, machine- en scheepsbouw. Stoom. Chemie. Telegrafie en telefonie. Zutphen: Walburg Pers.

Lintsen, Harry (1995). “Het verloren technisch paradijs” in: Bakker, M.S.C., E. Berkers, E. Homburg, H.W. Lintsen, P. Nijhof, and J.W. Schot (1995). Geschiedenis van de Techniek in Nederland: De Wording van een Moderne Samenleving. 1800-1890: Deel VI: Techniek en Samenleving. Walburg Pers, pp. 33-47.

Gerding, A.W. Michiel (2010). “Canals and energy. The relationship between canals and the
extraction of peat in the Netherlands 1500-1950”, Peat International, Vol. 2, No.10,
pp. 32-37.

Ormrod, David (2003). The rise of commercial empires England and the Netherlands in the age of mercantilism, 1650-1770. Cambridge: Cambridge University Press.

Perlin, John (2005). A forest journey: the story of wood and civilization. Woodstock, VT: The Countryman Press.

Hohenberg, Paul M. & Lynn Hollen Lees (1985). The making of urban Europe, 1000-1994. Cambridge, Mass: Harvard University Press.

Tellier, Luc-Normand (2009). Urban world history: an economic and geographical perspective. Québec: Presses de l’Université du Québec.

Strack, Maria. 2008. Peatlands and climate change. Calgary: University of Calgary.

Wikipedia, The Free Encyclopedia, s. v. “Vervening”, http://nl.wikipedia.org/wiki/Vervening.

Wikipedia, The Free Encyclopedia, s. v. “Turfsteken”, http://nl.wikipedia.org/wiki/Turfsteken.

Wikipedia, The Free Encyclopedia, s. v. “Veen (grondsoort)”, http://nl.wikipedia.org/wiki/Veen_(grondsoort).

Wikipedia, The Free Encyclopedia, s. v. “Slagturven”, http://nl.wikipedia.org/wiki/Slagturven.

Wikipedia, The Free Encyclopedia, s. v. “Baggerbeugel”, http://nl.wikipedia.org/wiki/Baggerbeugel.

Prak, Maarten Roy & Diane Webb (2005). The Dutch Republic in the seventeenth century: the Golden Age. Cambridge: Cambridge Univ. Press.

Lesger, Clé (2016). The rise of the Amsterdam market and information exchange: merchants, commercial expansion and change in the spatial economy of the Low Countries, c. 1550-1630. Aldershot: Ashgate.

“Turf fires -burning peat” (2009), Old and Interesting (website). http://www.oldandinteresting.com/peat-fire.aspx.

Tielhof, Milja van (2002). The “mother of all trades”: the Baltic grain trade in Amsterdam from late 16th to the early 19th century. Leiden: Brill.

Smil, Vaclav (2010). Energy transitions: history, requirements, prospects. Santa Barbara: Praeger.

De Decker, Kris (2011). “Medieval England twice as well off as today’s poorest nations”, No Tech Magazine, January 10, 2011. http://www.notechmagazine.com/2011/01/medieval-england-twice-as-well-off-as-todays-poorest-nations.html.

The Bright Future of Solar Thermal Powered Factories

To power industrial processes like the making of chemicals, the smelting of metals or the production of microchips, we need a renewable source of thermal energy.

Most of the talk about renewable energy is aimed at electricity production. However, most of the energy we need is heat. To power industrial processes like the making of chemicals, the smelting of metals or the production of microchips, we need a renewable source of thermal energy. Direct use of solar energy can be the solution.

Thermal Energy

A large share of energy consumed worldwide is by heat. Cooking, space heating and water heating dominate domestic energy consumption. In the UK, these activities account for 85 percent of domestic energy use, in Europe for 89 percent and in the USA for 61 percent (excluding cooking). Heat also dominates industrial energy consumption. In the UK, 76 percent of industrial energy consumption is heat. In Europe, this is 67 percent. I could not find figures for the US and for the world as a whole, but these percentages must be similar (and probably even higher on a worldwide scale because many energy-intensive industries have been outsourced to developing countries). Few things can be manufactured without heat.

We tend to see solar energy as yet another way to generate electricity, using photovoltaic panels or solar thermal power plants. But solar energy can also be applied directly, without the intermediate step of generating electricity. Basically, harvesting direct solar energy can happen in two ways: by means of water-based flat plate collectors or evacuated tube collectors, which collect solar radiation from all directions and can reach temperatures of 120 °C (248 °F), and by means of solar concentrator collectors, which track the sun, concentrate its radiation, and can generate much higher temperatures. These can be parabolic trough systems, linear concentrating Fresnel collectors, parabolic dish systems or solar power towers. Almost all of these technologies were developed at the turn of the twentieth century.

The problem is that we mostly use this technology for the wrong purpose. In today’s solar thermal plants, solar energy is converted into steam (via a steam boiler), which is then converted into electricity (via a steam turbine that drives an electric generator). In this process, two-thirds of energy gets lost when converted from steam to electricity. This is one of the main reasons why the use of solar thermal energy to produce electricity is only cost-effective in deserts. However, if we were to use solar thermal plants to generate heat instead of converting this heat into electricity, the technology could deliver energy three times cheaper than it does today and become cost-effective also in less sunny regions.

Low Temperature Solar Heat

This can be demonstrated by flat plate collectors and evacuated tube collectors, which are used for domestic hot water preparation and (to a lesser extent) interior space heating. This technology is used without any conversion losses and is cost-competitive with fossil fuels almost anywhere on Earth. According to the 2011 update of the International Energy Agency’s Solar Heating and Cooling Programme (IEA-SHC), solar thermal heat is now the second most important renewable energy source following wind, and a much more important energy source than photovoltaics and solar thermal power plants. Almost sixty percent of solar thermal heat capacity can be found in China and another twenty percent is in Europe. The US and Canada (where the main application is to heat swimming pools) account for less than nine percent.

Sweden, Denmark, Spain, Germany and Austria have the most sophisticated markets for different solar thermal applications, including large-scale plants for district heating and a small but growing number of systems for air conditioning and cooling (using an absorption chiller). By the end of 2009, 115 solar supported district heating networks and eleven solar supported cooling systems were installed in Europe. Canada, Saudi Arabia and Singapore have also built a few large-scale solar heat systems for producing hot water, space heating and cooling. Without a doubt, solar heat for domestic purposes should continue to be encouraged and a lot of potential remains. But it does not stop there.

According to a 2008 report, which analyses the situation in Europe, the potential for solar heat in industrial processes is even larger than in the domestic market. About thirty percent of industrial heat demand in Europe is below 100 °C (212 °F), which could be delivered by commercially available flat plate collectors (< 80 °C) and evacuated tube collectors (< 120 °C) currently used for domestic purposes. Another 27 percent of industrial heat demand requires medium temperatures (100 to 400 °C or 212 to 752 °F), which could be reached by improved versions of these collectors (up to 160 °C) and by commercially available solar concentrator technologies now mostly used for electricity production: parabolic troughs, parabolic dishes and linear concentrating Fresnel collectors.

This means that at least 57 percent of heat demand in European industry (or almost forty percent of total industrial energy demand) could be covered by available and cost-effective technology using an inexhaustible renewable energy source that has no ecological disadvantages whatsoever. The capital costs (and embodied energy) of this would be much less than replacing a similar amount of fossil fuel energy use with solar panels or wind turbines. And of course, it could be done anywhere, not just in Europe.

Solar Heat in Industry: Existing Applications

At low and medium temperatures, solar heat can be used for industrial processes in several ways. It can provide warm water for processes like bottle washing or chemical processes. Secondly, it can provide hot air for drying and baking processes, for instance in the food and paper industries. Thirdly, it can generate steam that can be fed into steam heat distribution networks, which are widely used in many industries. The interesting thing is that in all these applications, the existing industrial machinery and distribution infrastructure remains in place. Only the energy source is replaced. Some manufacturers have started marketing their solar concentrator technologies for the use of heat generation in industry, in addition to their application as electricity generators. Examples are Sopogy (a Hawaian company that sells modular parabolic trough systems), the Solar Power Group (a German company that sells linear concentrating Fresnel collectors) and HelioDynamics (an American seller offering similar technology).

Installations for the use of solar industrial process heat are still rare, but they exist. German heating systems manufacturer Viessmann installed 260 m² of its own flat plate collectors on its factory in France to provide hot water for a chemical process, taking a first step towards producing renewable energy using renewable energy. A solar thermal plant based on 1,900 m² of parabolic troughs provides steam for a pharmaceutical plant in Egypt. A similar solar thermal plant was built for a dairy plant in Greece. A food processing facility in California has 5,000 m² of parabolic troughs to produce steam used in the manufacturing process. Several industrial applications of solar heat have been built in India, using both flat plate collectors and concentrator technologies.

A solar concentrator system called ARUN – a Fresnel parabolic reflector with point focus that delivers temperatures from eighty to four hundred °C – has been installed in six industries, ranging from a dairy plant to an automobile manufacturer. India also has several large solar cooking facilities for community kitchens (schools, hospitals, factories, religious centres). The largest one consists of eighty-four parabolic dish systems reaching temperatures of up to 650 °C and producing up to 38,500 meals per day. The largest solar process heat application to date was recently installed in Hangzhou, China, where 13,000 m² of solar collectors on the roof of a textile factory provide hot water for a dyeing process.

High Temperature Solar Heat

The remaining 43 percent of industrial heat demand in Europe is above 400 °C (752 °F). These include many of the industrial processes that we need to manufacture renewable energy plants (wind turbines, solar panels, flat plate collectors and solar concentrators) as well as other sustainable technologies (like LEDs, batteries and bicycles). Examples include the production of glass (requiring temperatures up to 1,575 °C) and cement (1,450 °C), the recycling of aluminum (660 °C) and steel (1,520 °C), the production of steel (1,800 °C) and aluminum (2,000 °C) from mined ores, the firing of ceramics (1,000 to 1,400 °C) and the manufacturing of silicon microchips and solar cells (1,900 °C).

These temperatures can be achieved by solar concentrator technology. Linear reflectors (parabolic trough systems and linear concentrating Fresnel collectors) are limited to temperatures of about 400 °C, but point concentrators can reach higher temperatures. These include parabolic dish systems, solar power towers, and solar furnaces – which are basically a combination of power towers and parabolic dish systems. Solar furnaces can produce temperatures up to 3,500 °C (6,332 °F), enough to manufacture microchips, solar cells, carbon nanotubes, hydrogen and all metals (including tungsten which has a melting point of 3,400 °C). These temperatures can be achieved in just a few seconds.

The most powerful solar furnace is the one at Odeillo in France, built in 1970, which concentrates the light of the sun 10,000 times and has a power output of one MW. More than sixty heliostats direct the rays of the sun onto a parabolic mirror of more than 1,800 square metres, from which they are concentrated on a focal point with a diameter of only 40 centimetres in the tower in front of it. A similar solar furnace stands in Uzbekistan, built in 1976, but it is slightly less powerful due to lower solar insolation in the region. You don’t need such an enormous structure to achieve high temperatures. Several smaller solar furnaces have been built, often using only one heliostat. They reach similar or only slightly lower temperatures (usually between 1,500 and 3,000 °C), though at significantly lower power outputs (between 15 and 60 kW). They can perform most of the same processes as the large solar furnaces, but processing smaller amounts of materials or chemicals.

Examples of smaller solar furnaces can be found at the Paul Scherrer Institute in Switzerland, the National Renewable Energies Laboratory in the USA, the Plataforma Solar de Almería in Spain, the German Aerospace Center in Germany, and the Weizmann Institute of Science in Israel (a solar power tower). They have concentration ratios between 4,000 and 10,000. In solar concentration, the temperature is proportional to the degree of concentration, whereas power will be proportional to size and efficiency (which is mostly determined by temperature).

Improved Product Quality

Solar furnaces not only have the potential to replace fossil fuels for the energy-intensive production of construction materials, chemicals, and high-tech products like microchips and solar cells, but they also offer additional benefits because of their pure combustion and selective heating capacities. A 1999 research paper describes the manufacturing of silicon solar cells using a solar furnace, concluding that “solar furnace processing of silicon solar cells has the potential to improve cell efficiency, reduce cell fabrication costs, and also be an environmentally friendly manufacturing method. We have also demonstrated that a solar furnace can be used to achieve solid-phase crystallization of amorphous silicon at very high speed.”

As opposed to low and medium temperature processes in industry, where only the energy source is replaced and the machinery and distribution infrastructure can remain in place, most high temperature solar heat applications require new machinery. Furnaces and kilns have to be rebuilt. Some efforts have been made. The Paul Sherrer Institute in Switzerland designed several solar powered lime and cement kilns, and research concluded that they could become cost competitive with a fossil fuel powered kiln following some further technological improvements. Again, the quality of the product turned out to be better using solar energy, eliminating combustion by-products.

Though existing solar funaces prove that anything could be produced using direct solar heat instead of fossil fuels, this is not yet possible in a cost-effective way (it is cheaper to use fossil fuels). However, since solar furnaces could produce all materials needed to build more solar furnaces, they might become cost-effective even without technical improvements if fossil fuels become more expensive. Moreover, the capital costs of solar concentrators are decreasing quickly following some recent innovations aimed at simplifying the technology. These might not only lead to cheaper high temperature solar heat concentrators in the future, but they also make the use of solar heat for medium temperatures more affordable and competitive today.

Energy Autonomy

The most interesting example is the Solar Fire P32, a solar concentrator developed in 2010 by the French NGO the Solar Fire Project. It is an open source design (joining forces with the Open Source Ecology project), but the machine can also be bought for 7,500 euro dollar - less than the price of an urban wind turbine. Solar Fire P32 is built using simple, abundant and non toxic materials. Contrary to most other modern green technologies, there is no need for rare earth metals or advanced tools that are not found in an average metal workshop. Essentially, this is a renewable source of heat energy analogous to home made windmills used to produce mechanical energy.

The machine can deliver up to fifteen kW and can reach a focal temperature of 700 °C (1,292 °F), enough to melt (and thus recycle) aluminum, the material that is used to make its reflectors. This means that you could use a Solar Fire P32 to make another Solar Fire P32. Or almost. The receiver and the supporting structure are made of steel, which requires a higher melting temperature to recycle. However, the structure could as well be made of wood, basketry or aluminum, and the steel receiver could easily be scavenged material. The use of glass improves the workings of the device, but is not strictly necessary.

The Solar Fire P32 is composed of 360 small mirrors with a total surface of 32 square metres, focusing sunlight on a steam boiler above them. The steam can be used directly to purify large quantities of water, boil milk, produce edible oils, make charcoal, bake bricks, make paper, and so on. The steam can also drive a steam engine to directly power a water pump, oil and grain mills, cotton spinning, or any other stationary application requiring mechanical power. Connected to a steam generator, the machine can also generate electricity (up to three kW). These two last applications involve conversion losses, but they are interesting additions for those who want to achieve energy independence, especially in regions where there is lots of sun but no wind. The machine can produce heat, electricity and direct mechanical energy.

The Solar Fire P32 is – in the first place – aimed at developing countries and designed to be cost-effective compared to burning coal and wood, reducing deforestation and pollution, increasing energy autonomy, and providing an energy source at the scale of traditional practices and small industries. It has been built in Mexico, Cuba, Burkina-Faso, Mali, India and Kenya, but also in Texas, France and Canada. Obviously, the design could also be useful in the developed world, where the supply of fossil fuels might not remain as easily accessible as it is today.

Simplifying Technology

Apart from the additional equipment that is required to generate electricity, conventional solar concentrator technologies demand heavy capital investments for several reasons. Parabolic trough systems and parabolic dish systems require curved mirrors that are expensive to produce. Moreover, these mirrors cannot be manufactured locally and often have to be transported over long distances, increasing costs further. In both systems the curved mirrors are large and heavy, requiring rigid frames, strong foundations, powerful hydraulics and sophisticated tracking systems to follow the sun. In parabolic dish systems, the heat engine or steam boiler is part of the moving structure, increasing weight and thus making things even worse.

Solar power towers – which were invented in 1878 – solve some of these issues: they use nearly flat mirrors and all mirrors share one stationary receiver. But, they require the construction of a large tower building. Last but not least, all of these systems have very high land requirements because of overshadowing issues. Linear Fresnel concentrators use (mostly) flat mirrors, have simpler tracking systems and are more compact, but they can only reach temperatures of 250 °C (using relatively low-tech materials) or 450 °C (using sophisticated technology). Solar Fire is a Fresnel parabolic reflector with point focus, just like ARUN – but unlike that machine it is placed horizontally and the receiver does not have to be turned together with the mirrors, resulting in light weight and high wind resistance.

The machine uses slightly curved mirrors, achieved by mechanical bending which can be done on the spot. Sun tracking of the mirrors is done by hand, eliminating the need for electronics and electric motors altogether (multiple mirrors can be turned at once using hand operated wheels). This might sound crude, but for industrial applications the machine has to be supervised anyway. And because it is open source, it can be further improved by anyone. Eerik Wissenz, the designer of the machine, thinks this is the only way:

Companies pursuing patents for solar collectors have fallen into a complexity trap. Since solar energy is free it is far simpler to add 5 percent more surface area instead of creating complex machines too expensive to be commercially viable. Solar fire concentration is so simple it cannot be patented.

High temperature solar furnaces can be low-tech autonomous systems, too. One example is the large magnifying glass used by Sundrop Jewelry, which reaches high enough temperatures to melt coloured bottle glass into handcrafted jewelry. Of course the power output is low, making this installation useless if you want to produce industrial quantities of glass. But it shows that solar heat can be used on any scale. Another example is the Solar Sinter Project by Markus Kayser, in which glass is produced using only sunlight and desert sand. I would like to quote the artist here: “Whilst not providing definitive answers, this experiment aims to provide a point of departure for fresh thinking”.

Heat Storage

How can you power factories using an energy source that is not always available? Solar insolation varies throughout the day and the seasons, and there is no sun at night. Moreover, solar concentrator technologies only work with unscattered sunlight, which means that a passing cloud stops energy production. This raises two questions. Some industrial processes work fine with intermittent energy supply, but how do you guarantee an uninterrupted supply of energy to a process that requires it? And what do you do when there is no sun at all for a week?

There are three ways to deal with the intermittency of solar power. The first solution is to design hybrid systems: make solar and already existing energy sources work together. This is how most of today’s solar thermal power plants work. In this scenario, which offers a solution for both short and long term storage, industrial processes are powered by solar heat whenever it is available. When it is not, solar energy is instantly replaced by fossil fuels or electricity. It is not an ideal solution, but it could save large amounts of energy. And we don’t need new technology to make it work.

The second strategy is to store solar energy so that it can be used to smooth out industrial processes (analogous to a flywheel for smoothing out mechanical processes) and to guarantee energy supply on cloudy days or at night. Storage of heat is much cheaper and more efficient than storage of electricity. The most low-tech way is to store heat in well-insulated water reservoirs. The disadvantages are that you need quite a lot of space, and that water storage only works up to a temperature of 100 °C (212 °F). There are more compact ways to store heat at higher temperatures, for example by using ceramics or phase changing materials (certain salts). These storage media are already used in one solar thermal power plant, but they would be even more efficient if used in a thermal only system. Innovative technology could further improve heat storage.

The third way to deal with the intermittency of solar heat is to “store” work instead of energy. We let our factories work when the sun shines, and only when the sun shines. Just like we wait for a sunny day to do the laundry, we could wait for a sunny day to bake bricks, recycle metal or produce smartphones. Industrial production would be concentrated in summer months. Of course, there is a price to pay. Industrial production would be lower. But considering the fact that our energy and environmental problems are largely caused by overproduction and overconsumption of goods, this is not as far-fetched as it might seem.

Combining all three strategies could be a solution. In that scenario we would run part of our factories only when the sun shines (and when the wind blows), using heat storage, fossil fuels, biomass or electricity to smooth out industrial processes if necessary. Critical goods could be produced continuously combining solar heat and heat storage, fossil fuels, or biomass. Of course, not all climates are blessed with enough sun to make solar heat a viable option to power the whole industry. But since many people are now talking about outsourcing electricity production to desert regions, we could just as well move our factories to regions where there is plenty of sun. It is much more efficient to transport manufactured goods over large distances than to transport electricity.

Solar Powered Enhanced Oil Recovery

As always, a sustainable technology can be used for unsustainable purposes. Solar heat is a great way to get more oil out of fields that are now considered exhausted. Getting that remaining oil out using gas would cost more money and energy than the oil could return, but using a free source of energy changes everything. At least one company specializes in this application. Glasspoint, a US firm originally founded to use solar heat for drying gypsum wall board, has seen remarkable growth promoting Solar Enhanced Oil Recovery.

This has been tried before, but they use an innovative technology: parabolic trough mirrors suspended from the ceiling of enormous glasshouse structures that are equipped with robotic cleaning systems. Because they are protected from wind, sand and dust by the greenhouse, the mirrors can be made extremely light and without protective glass layers – lowering their costs and increasing their efficiency. The steam that is generated by the solar heat is pumped into the oil reservoir. The more sun there is, the more oil will come to the surface. Only 20 to 40 percent of an oil field can be recovered using standard techniques, but as much as 60 to 80 percent can be recovered using solar heat, according to Glasspoint. In the end, solar heat could thus increase fossil fuel production and CO2-emissions. ←

Solar thermal collector for milk pasteurisation in Mahanand Dairy, Latur, India. Image credit: Arun.

Heat demand in European industry. Source: SHC Task 33: Solar heat for industrial purposes. Solar heating and cooling programme (SHC), International Energy Agency, 2006.

The most powerful solar furnace in the world, Odeillo, France. Björn Appel (CC-BY-SA-2.5).

A solar furnace in Uzbekistan, melting metal. Pluviales (CC BY-NC 2.0)

The Solar Fire. Image: Eerik Wissenz.

Erin McKittrick is melting glass coloured bottle glas into handcrafted jewelry, using a 30’’x40’’ fresnel lens. Image: Sundrop Jewelry.

References

Department for Business, Energy & Industrial Strategy (2013-2019). “Digest of United Kingdom Energy Statistics (DUKES)”. http://www.decc.gov.uk/en/content/cms/statistics/publications/dukes/dukes.aspx

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European Solar Thermal Industry Federation (2006). “Solar Industrial Process Heat – State of the Art”, part of the Key Issues for Renewable Heat in Europe (K4RES-H) project, Intelligent Energy Europe, August 25, 2006. http://www.estif.org/fileadmin/estif/content/policies/downloads/D23-solar-industrial-process-heat.pdf.

Wissenz, Eerik (2011). “The Thermal Problem”,
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Lots of links to DIY-projects. Thanks to Paul Nash.

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& Unesco (2009). Solar energy conversion and photoenergy systems. Oxford: Eolss Publishers.

Daniels, Farrington (1964). Direct Use of the Sun’s Energy. Bronx, NY: Ishi Press.

Steinfeld, Aldo & Robert Palumbo (2001). “Solar thermochemical process technology” in: Meyers, R.A. (Ed.) (2001). Encyclopedia of Physical science and technology. Academic Press, Vol. 15, pp. 237-256, 2001.

Sioshansi, R., Denholm, P., Ohio State University,
& National Renewable Energy Laboratory (U.S.) (2010). The value of concentrating solar power and thermal energy storage. Golden, CO: National Renewable Energy Laboratory.

Kaplan, G. M., & Volunteers in Technical Assistance. (1985). Understanding solar concentrators. Arlington, Va: Volunteers in Technical Assistance.

So-Pro (website, 2019). http://www.solar-process-heat.eu.

European project on solar process heat

Solar Heat Europe (website, 2019). http://solarheateurope.eu.

The European Alliance SolLab: Alliance of European Laboratories for Research and Technology on Solar Concentrating Systems (website, 2000). http://www.sollab.eu.

“CSP- how it works” (2007), SolarPACES (website, 2002).Accessible through https://web.archive.org/web/20071001095549/http://www.solarpaces.org/CSP_Technology/csp_technology.htm.

Sundrop Jewelry (website). http://www.sundropjewelry.com/.

Glass Point (website). http://www.glasspoint.com/.

The Short History of Early Pedal Powered Machines

From the 1870s onwards, pedals and cranks were attached to tools like lathes, saws, grinders, shapers, tool sharpeners and to boring, drilling and cutting machines.

Ever since the arrival of fossil fuels and electricity, human powered tools and machines have been viewed as an obsolete technology. This makes it easy to forget that there has been a great deal of progress in their design, largely improving their productivity. The most efficient mechanism to harvest human energy appeared in the late 19th century: pedalling. Stationary pedal powered machines went through a boom at the turn of the 20th century, but the arrival of cheap electricity and fossil fuels abruptly stopped all further development.

Hand Cranks, Capstans & Treadwheels

Rotary motion has been the fundamental mechanism of most machines throughout human history. There have been several important innovations in applying human power to rotary motion, many of which already appeared in Antiquity: the bow, the hand crank, the capstan and the treadwheel. Successively, each of these brought an improved mechanical advantage, being the factor by which the mechanism multiplied the human (or sometimes animal) input force into an higher output force. A hand crank had a mechanical advantage of about two to one, meaning that the mechanism doubled the effort of the user. With a capstan, the mechanical advantage went up to about six to one.

A typical treadwheel, which had a diameter of at least four metres, had a mechanical advantage of about fourteen to one. This meant that a person walking a treadwheel could exert seven times more ‘torque’ (the force to rotate an object about an axis) than a person operating a hand crank. Or, that a person could generate the same amount of torque with seven times less effort. The treadwheel had another advantage over the hand crank: it replaced the use of the arm muscles by the use of the much stronger leg muscles, and it allowed the use of two limbs instead of one. The same effort could thus be sustained over a longer time – or a higher force could be exerted over the same time. To a lesser extent, the same advantage was valid for the capstan, where the legs did a large part of the work.

Another novelty appeared in the Middle Ages: the treadle. From the tenth century onwards, the Chinese used wooden treadles to obtain continuous motion for water pumps, textile machinery and wood saws. In the western world, treadles were mainly applied to spinning wheels and lathes (machine tools used for working metal and wood). Treadles were inefficient compared to capstans and treadwheels (feet and legs must be accelerated and subsequently decelerated by the muscles) but they were more compact and a viable alternative when power requirements were low. Their main advantage over the hand crank was that they left both hands free to control the machine.

A Boom of Pedal Powered Machines

The cleverest innovation in applying human power to rotary motion only appeared in the 1870s. Some of us still use it as a means of transportation, but it is rarely applied to stationary machines anymore: pedal power. Initially, pedals and cranks were connected directly to the front (or sometimes rear) wheel. With the arrival of the safety bicycle shortly afterwards, this direct power transmission was replaced by a chain drive and sprockets - still the basics of most present-day bicycles. Pedal power did not come out of the blue: some of the first bicycles were equipped with treadles, which could be considered the predecessor of the pedal.

On their own, pedals and cranks did not offer a better mechanical advantage than the hand crank, let alone the capstan or the treadwheel. What made pedal power so revolutionary was that it offered the possibility to use the stronger leg muscles in a continuous motion while at the same time offering a much more compact mechanism than the capstan or the treadwheel. Moreover, using the appropriate gear ratio (using chains and sprockets of different sizes) a mechanical advantage similar to that of a capstan or a treadwheel could be achieved (multiplying torque at the expense of speed or vice versa). This made pedal power suitable for a much larger variety of applications.

From 1876 onwards, pedals and cranks were attached to tools like lathes, saws, grinders, shapers, tool sharpeners and to boring, drilling and cutting machines. These machines – which became very popular – were intended for small workshops and households without electricity or steam power. They were made with heavy cast-iron bodies that could be collapsed for shipping. Pedals and cranks did not make treadles and hand cranks obsolete. On the contrary, these tools became more sophisticated (made of steel instead of wood, for example, or using gears inspired by bicycles) and became increasingly popular for low or brief power applications. Steel treadles were applied to industrial machines like hat, broom, cigar and hook making machines, printing presses, punch machines and riveting machines. The farm saw the appearance of foot powered harvesters, treshers, milking machines and vegetable bundlers. The late nineteenth century dentist used a treadle powered drill.

Ending Human Drudgery

The historical importance of pedal powered machines can be easily overlooked by people who grew accustomed to fossil fuels and ubiquitous electricity. Therefore, it cannot be stressed enough how much of an improvement pedal power was in the light of thousands of years of human drudgery. Pedals and cranks make use of human power in a near-optimum way. The circular pedalling motion mainly activates the thigh muscles or quadriceps which are the largest and most powerful muscles in the human body. Furthermore, using the appropriate gearing, pedals and cranks make use of these muscles at an optimal speed: about sixty to ninety revolutions per minute. Research in the twentieth century has shown that muscles develop maximum power when they are contracting quickly against a small resistance.

Historically, the motions used to harvest human muscle power used inappropriate muscles moving against resistances which were too large at speeds which were too low. While human powered capstans and treadwheels were much more efficient, their use was limited because of their sheer size (and especially in the case of treadwheels, their high costs). In the 1977 book Pedal Power in Work, Leisure and Transportation, David Wilson explains three ways in which the application of human muscle power could fall short of the optimum:

First, the wrong muscles could be involved. We find time and time again that people were called upon to produce maximum power output, for instance in pumping or lifting water from a well or ditch, using only their arm and back muscles. Second, the speed of the muscle motion was usually far too low. People were required to heave and shove with all their might, gaining an occasional inch or two. A modern parallel would be to force bicyclists to pedal up the steepest hills in the highest gears, or to require oarsmen to row boats with very long oars having very short inboard handles. Third, the type of motion itself, even if carried out at the best speed using the leg muscles, could be nonoptimum in a rather abstruse way.

Good examples of the misuse of human muscle power throughout history were large human powered rowing boats, as well as most farm work. In the third edition of Bicycling Science, the same David Wilson writes:

The muscle actions used by these unfortunate oarsmen were typical of those considered appropriate in the ancient world. The hand, arm and back muscles were used the most, while the largest muscles in the body – those in the legs – were used merely to provide props or reaction forces (they didn’t have the sliding seat of today’s competitive rowers). The motion was generally one of straining mightily against a slowly yielding resistance. With five men on the inboard end of a sweep, the one at the extreme end would have a more rapid motion than the one nearest to the pivot, but even the end man would probably be working at well below his optimum speed. Most farm work and forestry fell into the same general category. Hoeing, digging, sawing, chopping, pitchforking, and shoveling all used predominantly the arm and back muscles with little useful output from the leg muscles. In many cases, the muscles had to strain against stiff resistances.

Industrial Revolution

All these actions – and many more – could have been made much more efficient using pedals and cranks, making the life of people in Antiquity and medieval times much easier. However, no matter how simple it seems to us today, pedal power could not have appeared earlier in history. Pedals and cranks are products of the industrial revolution, made possible by the combination of cheap steel (itself a product of fossil fuels) and mass production techniques, resulting in strong yet compact sprockets, chains, ball bearings and other metal parts.

Prior to that time, the available materials were not strong enough to take the large force that was acted upon them. This is even truer for stationary pedal power than for road bicycles, because the strain on parts is considerably larger. Experiments in the 1970s designing pedals, cranks and bearings for stationary pedal power units using pre-industrial materials like wood failed. And while the frame of a pedal powered machine can be made of wood or bamboo, steel is a better option – contrary to road bicycles, a lightweight frame is not an advantage for a stationary machine.

It is important to realise that pedal powered machines (and bicycles) require fossil fuels. If we burn up all fossil fuels driving cars, we won’t be able to revert to bicycles, we will have to walk. If we burn up all fossil fuels making electricity to run our appliances, we won’t be able to revert to pedal powered machines, but to the drudgery that went before them. And yet, this is what we are heading to. In spite of the many advantages of pedals and cranks, the heydays of pedal power were over fast – shortly after the arrival of the combustion engine and the electric motor. Even though pedal powered machines were designed to operate for a hundred years or more, most were scrapped for metal during World War I & II. The Barnes Company, one of the most famous manufacturers, began turning away from foot powered tools in the 1920s and stopped producing them altogether in 1937. ←

A pedal powered saw, late nineteenth century.

A pedal powered lathe, late nineteenth century.

References

McCullagh, James (ed.)(1977). Pedal Power in Work, Leisure and Transportation. Emmaus, PA: Rodale Press.

Still the best resource on pedal powered machines.

Dean, Tamara (2008). The human-powered home choosing muscles over motors. Gabriola Island: New Society.

Very good book on human powered machines, both hand and foot powered. Includes half a dozen plans to convert bicycles into stationary pedal powered machines.

Wilson, David G. (2004). Bicycling Science. London: MIT Press.

Weir, Alexander (1980). The Dynapod: a pedal power unit. Mt. Rainier, MD: Volunteers in Technical Assistance.

Weightman, D., & Intermediate Technology Development Group (1976). The Use of pedal power for agriculture and transport in developing countries. Coventry: Lanchester Polytechnic.

Cyders, T. J. (2008). Design of a human-powered utility vehicle for developing communities (dissertation). Ohio: Ohio University.

National Research Council (U.S.)., National Academy of Sciences (U.S.)., United States., & National Academy of Sciences (U.S.). (1981). Energy for rural development: Renewable resources and alternative technologies for developing countries: a report of. United States: Knowledge Publications.

Brett, D. (2003). Tales from the Blue Ox: (a hands-on manual of traditional skills from the Blue Ox Millworks Historic Park). Mendham, NJ: Astragal Press.

Sharp, Archibald (1896). Bicycles and tricycles: an elementary treatise on their design and construction, with examples and tables. London, New York: Longmans, Green.

Allen, John S. (1991). “In search of the massless flywheel”, Human Power: Technical Journal of the IHPVA, Vol. 9, No. 3, p. 10.

Modak, J. P. & S. D. Moghe (1998). “Design and development of a human-powered machine for the manufacture of lime-flyash-sand bricks”, Human Power: Technical Journal of the IHPVA, Vol. 13, No. 2, pp. 3-8.

Modak, J.P. (2007). “Human Powered Flywheel Motor: concept, design, dynamics and applications”. In: World Congress in Mechanism and Machine Science, & Merlet, J.-P. (2007). Proceedings of twelfth world congress in mechanism and machine science: June 17-21, 2007: Besancon, France. França: s.n.

Park, Benjamin (1892). Modern mechanism: exhibiting the latest progress in machines,motors, and the transmission of power. London, New York: MacMillan

Gulland, John (2008). “Make electricity while you exercise”, Mother Earth News (website). https://www.motherearthnews.com/renewable-energy/pedal-powered-generators-zmaz08onzgoe.

Luther Grinder Manufacturing Company (1913). Luther’s “Demo-grit” grinders. Milwaukee, Wis: Luther Grinder Mfg. Co.

Hand and foot powered grinders catalog.

Hosted at Toolemera Blog, toolemera.com.

Melhuish, Richard Ltd. (1925). Woodworkers’ tools and machines catalogue, No. 25. Londen: Melhuish.

Hosted at Toolemera Blog, toolemera.com.

Needham, Joseph (1988). Science and technology in China Volume V: 9. Cambridge; New York: Cambridge University Press.

“Pedal Powered Stage Gear”, Rock the Bike (website, 2019). http://rockthebike.com/pedal-powered-stage-gear.

“The Future Spark Vision”, Future Spark (website, 2008). Accessible through https://web.archive.org/web/20130511035949/http://www.futurespark.com.au/about-future-spark.

Electric Pedals (website, 2019). http://electricpedals.com/events/pedal-powered-cinema-2/.

Cinema, smoothies, school workshops, ...

Mellor, Chris (2007). “MIT students power supercomputer with bicycles”, Computerworld, December 20, 2007. http://www.computerworld. com.au/article/201723/mit_students_power_ supercomputer_bicycles/.

Erikson, Ben. “CCAT pedal powered energy generator: Human Powered Energy Generator (HPEG)”, Appropedia, (accessed August 5, 2019), http://www.appropedia.org/CCAT_
pedal_powered_ energy_generator.

Gilmore, Adam M. (2008). “Human Power: Energy Recovery from Recreational Activity”, Guelph Engineering Journal, Vol. 1, pp. 8-16.

Stevens, John W. & Garth P. Corey, Sandia National Laboratories, and United States (1996).
“A Study of Lead-Acid Battery Efficiency Near Top-of-Charge and the Impact on PV System Design” (conference publication), Washington, D.C.: United States. Dept. of Energy.

“A Guide To Lead-Acid Batteries”, ITACA (website). http://www.itacanet.org/eng/elec/battery/battery.pdf.

“Parts and accessories”, Magnificent Revolution (website, 2012). Accessible through https://web.archive.org/web/20120310034243/http://www.magnificentrevolution.org/shop/parts-accessories/.

“DC-DC Regulator Module: Input 13-17 VDC / Output 12VDC (4 Amp rate with removable heat sink)”, AA Portable Power Corp (website, 2019).

http://www.batteryspace.com/dc-dcregulatormodule13-17vdcto12vdc4ampratewithremovableheatsink.aspx.

Alstone, Peter & Lai, Patricia & Mills, Evan & Arne Jacobson (2014). “High Life Cycle Efficacy Explains Fast Energy Payback for Improved Off-Grid Lighting Systems”, Journal of Industrial Ecology, Vol. 18, No. 5, pp.722-733.

Kaldellis J.K., Zafirakis D. & E. Kondili (2009). “Optimum autonomous stand-alone photovoltaic system design on the basis of energy pay-back analysis”. Energy, Vol. 34, No. 9, pp. 1187-1198.

“Can the Lead-acid Battery Compete in Modern Times?”, Battery University (website, 2019). https://batteryuniversity.com/index.php/learn/archive/can_the_lead_acid_battery_
compete_in_modern_times.

“How much energy does it take (on average) to
produce 1 kilogram of the following materials?”, Low-tech Magazine.
https://www.lowtechmagazine.com/what-is-the-embodied-energy-of-materials.html.

Pedal Powered Farms and Factories: The Forgotten Future of the Stationary Bicycle

The possibilities of pedal power largely exceed the use of the bicycle.

Following their short success in the begin of the twentieth century, pedal powered machines resurged in the 1970s, together with the bicycle, following the first oil crisis. Because the further development of stationary pedal powered machines had been halted for more than five decades, there was a lot of work ahead in order to modernise the technology.

Several individuals and organisations experimented with a new generation of pedal powered machines. Although their efforts did not result in commercially available machines, a great deal of progress was made. The applications of pedal power were extended to include almost every possible machine. Moreover, several inventors designed and build universal pedal power units, which could be used to drive a wide range of tools.

Direct Mechanical Power Transmission

Many machines could be powered by a direct mechanical connection, though it generally means adapting the device so that it can work independently of electricity. However, stationary pedal machines with direct mechanical power transmission – although they were common in the old days – are not available commercially in the western world. The only exception seems to be the Fender Blender, a pedal powered machine used to make smoothies. However, old school bicycle machines are now being designed both by amateurs in the western world and non-profit organisations in the developing world.

In Guatemala, Mayapedal has been building some 2,000 pedal powered machines from old bicycle parts since 2001. To date, the NGO has built pedal powered water pumps, grinders, threshers, tile makers, nut shellers, washing machines and blenders. These cost only $40 to $250 to make. Their contraptions have become more sophisticated and even cheaper to build over time, evolving from adapted bicycles to pedal powered machines built from scratch which incorporate a flywheel, and are capable of driving different types of appliances.

Another example is the VitaGoat Cycle Grinder developed by the Canadian NGO Malnutrition Matters. The pedal powered grinder forms part of a complete food processing system which is delivered to developing countries in Asia and Africa. Then there are the many contraptions built by individuals: the pedal powered washing machines by Alex Gadsden and Homeless Dave, the pedal powered soap blender by Frederick Breeden, or the pedal powered apple grinder by Ben Polito. Similar machines have also been built outside the US. Some have concentrated on restoring and putting to use antique machines, like Blue Ox Millworks.

Multi-Purpose Pedal Powered Machines

One obvious disadvantage of designing a pedal powered machine for every application in the household, farm or workshop is that you need a lot of space. Furthermore, designing a pedal power unit for every tool might become labour intensive, costly and energy-intensive. This is not as much of a problem in cases of small-scale industrial use, where few machines are required in order to manufacture a product. A good example of this is the pedal powered soap blender mentioned above. For this reason, a pedal powered blender could be a realistic option for small businesses, such as a smoothie bar.

However, when more tools are needed and space is restricted, as is often the case, we need to find ways to get around this problem. One solution is to use pedal power to generate electricity which can then be used to power different devices. However, this approach is highly inefficient with energy losses of up to more than seventy percent and should be avoided whenever a device can be powered in a mechanical way. Another solution is to design a universal pedal power unit with direct mechanical transmission that can be used to operate a large variety of different tools and devices (and which can include an electric generator). This method, which solves both the space and inefficiency problem, was extensively researched in the 1970s.

Universal pedal powered machines did not exist at the turn of the twentieth century, although some combined a few functions (both sawing and drilling, for instance). At least five interesting inventions were designed and built in the 1970s: the Energy Cycle (by Dirk Ott), the Dynapod (by Alex Weir), the Human Powered Flywheel Motor (by JP Modak), the Pedal Power Unit (by David Weightman) and the Dual-Purpose Bicycle (by Job Ebenezer). All these concepts are also of interest for the construction of single-purpose pedal power units.

The Dynapod

After experimenting with single-purpose pedal powered machines in several countries in Africa, British engineer Alex Weir built a multi-purpose Dynapod (the name stemming from the Greek words for ‘power’ and ‘foot’) in Tanzania in the early 1970s. The power module, based on a 1968 concept by Stuart Wilson of Oxford University, came in a one-man and two-man version. The tandem unit doubled the power output, and at the same time evened out the power flow, with both sets of pedals placed out of phase. The Dynapod was made using a custom-built frame. Apart from pedals, cranks and chain drives, the machine shared nothing with a bicycle. The first designs used wooden frames, while later versions were based on a steel frame. For a flywheel, Weir used an old bicycle wheel filled with cement. The cost of the wooden frame unit (in 1980) was forty to a hundred dollars, materials and labour included.

The Dynapod could drive pumps, corn grinders, winnowing machines, forge blowers, grinding machines, drilling machines, potter’s wheels, paint sprayers, crop dusting equipment, cassave graters, coffee pulpers, grain hullers, fibre decorticators, threshers, balers, band saws, tire pumps and sewing machines. It could also be used to generate electricity. To allow the operation of such a wide diversity of appliances, the Dynapod was equipped with multiple drives. It could be operated with a direct drive having a ratio of 1:1 (when a lot of torque was needed at a slow speed), a chain drive with a ratio of up to 3:1 (a compromise between torque and speed for operating grinders, threshers, etc.) or a belt drive with a ratio of up to 10:1 (for electrical generation, a winnowing fan, and other uses where high speeds were required). The machine was easily adapted from one drive to another. Multiple drives on pedal powered machines were not a novelty – some earlier pedal powered machines had them too.

The Energy Cycle

Rodale Press, the publisher of the 1977 book Pedal Power in Work, Leisure and Transportation also had a research team – Rodale’s Research and Development Department. Together with inventor Dick Ott they conceived their version of a universal pedal power unit, the Energy Cycle. Just like the Dynapod, it was built from scratch and could accommodate a large number of detachable tools. These included kitchen aids (such as an egg beater, can opener, nut chopper, food grinder, fish skinner, meat and cheese slicer and a cherry pitter), farm machinery (including an irrigation water pump, feather plucker, potato digger, corn sheller, grain cleaner, rice polisher and oatmeal roller) and more general tools (like a wheel grinder, stone polisher, drill, wood carver and battery charger).

Several improved prototypes were built, first of iron, and then of steel. For the first upgrade of the design, a large work table was added to the unit which enabled the operator to perform numerous tasks without leaving his seat. Later versions were equipped with a flywheel. Experiments showed that the unit offered considerable benefits in comparison with hand powered machines or small horse power motors and engines. The main challenge remains in finding a universal means of attaching each implement to the Energy Cycle – which should be easily overcome if serious industrial research is dedicated to it.

Pedal Powered Winch: Substituting a Farm Horse or Tractor

Both the Dynapod and the Energy Cycle could also double up as a pedal powered winch, offering a whole new array of possibilities. A winch is useful for pulling, excavating, load lifting, or snow plowing. In agriculture, a winch can be utilized for cable-cultivation, a principle in which the motive power for plowing (or harrowing, cultivating, seeding and hay raking) is stationary and only the tool (attached to a multifunctional mobile tool carrier) moves across the field along a cable. This agricultural method is based on steam cable plowing, which was the only mechanized method of agriculture for almost one hundred years. Cable cultivation brings considerable savings in energy, because the motive power – be it human, animal or mechanical – does not have to waste power in moving itself over the soil.

Additional advantages are the avoidance of soil compaction, a notable drawback of using a tractor, and the possibility to work on waterlogged ground and steep slopes. In a field left fallow for a year, the Energy Cycle pulled a plough through the grass and weed covered soil, successfully substituting the work of a farm horse or tractor. One person pedalled the winch that drew the plough through the soil while another guided it. It took the two persons about an hour to plow 1,500 square feet. The only difficulty was that the winch had the tendency to break or bend ordinary hand tools. Because of this problem, and because the Energy Cycle held so much promise as a garden and farm tool, the research team built a specialized pedal powered winch and special tools to be used with it.

This more compact unit – basically two pedals separated by a spool mounted on bearings, built into a frame which also supports the seat – was capable of pulling over one thousand lbs (453 kg) with average pedalling effort, amplifying human power by almost ten times. Together with a specially designed frame that could hold different attachments, it was successfully used for pulling, snow plowing, dislodging small stumps and pulling seeders, harrows and hay rakes. Low gears were used for jobs requiring a slow, powerful pull, such as plowing through heavy soil. Second or high gears were used for easier jobs such as harrowing or cultivating. In order to be moved sideways so as to easily cultivate one row after the other, a pedal powered winch can be mounted on skids. The weight of the operator provides sufficient anchorage while in use.

Human Powered Flywheel Motor

An interesting variation on the multi-purpose pedal powered machine is the Human Powered Flywheel Motor designed by J.P. Modak, an emeritus engineering professor from India. The remarkable feature of Modak’s machine – which has been developed since 1979 – is that it can deliver much more power than the human who operates it. The machine system uses human energy and stores it in a flywheel at an energy-input rate convenient to the pedaller. After storing the maximum possible energy in the flywheel (pedalling time is one to two minutes), it is made available for the actuation of the process unit by the rapid release of the stored kinetic energy in the flywheel via a suitable clutch. The concept only works when the process can be of intermittent nature without affecting the end product.

The human powered flywheel motor was initially developed for the making of bricks for a housing authority in Mumbai, India. Since then, it has been successfully used for several rural-based production activities such as water lifting, algae formation processing, wood turning, winnowing, wood strip cutting, electricity generation and the operation of a smiths hammer. Processes needing up to six HP could be energised by the machine concept (although only one third of this has been achieved to date). This would be about twenty to sixty times more than what an average human can sustain either momentarily (three hundred watts) or for long periods (one hundred watts). The energy unit consists of an existing bicycle frame which provides a seat and handle, a pair of speed-increasing gears, and a flywheel of about one metre in diameter. The transmission consists of a spiral clutch and a torque-amplification gear pair. For brick manufacturing in particular, the process unit consists of an auger, cone and die, conventionally used for motorized brick-extruders for the manufacture of clay bricks.

Combining Stationary and Mobile Pedal Power

A very different approach to multi-purpose pedal powered machines was followed by David Weightman. His concept (and prototype) was inspired by the Dynapod, but Weightman added one feature: the machine should still be usable for transportation. His Pedal Power Unit (PPU) was comprised of a bicycle wheel in forks fitted to a frame with a saddle. The unit could then be used independently to drive machinery via a power takeoff but could also be connected to a two-wheel chassis to form a load-carrying tricycle. Furthermore, the unit could be connected in series with other units for machine applications requiring more power. Weightman justified his concept by emphasising the close link between transport and machine use in agricultural and industrial production:

In a typical agricultural growing cycle, seed and fertilizer are transported to the field, crops are grown and then processed by machinery, and then produce is transported to the market. Similar patterns can be seen in construction and small scale industrial production. The use of a pedal power unit in this dual purpose role is exactly analagous to the use of tractors in European agriculture as power sources and transport devices. The PPU is equally suitable as the Dynapod when operating a number of machines but is more economically feasible for an individual farmer due to its capability as a transport device.

Job Ebenezer from the NGO Technology for the Poor further developed this design, simplifying it greatly by substituting the tricycle for a bicycle. At first sight, his Dual-Purpose Bicycle looks very similar to the electricity generating units which are sold today, though it is aimed at mechanically driving multiple machines and producing electricity. The ingenious design, primarily for agricultural use, consists of a very small flywheel attached to a standard bicycle, which permits its use as a pedal-powered machine that can be utilized to power numerous small-scale mechanical devices such as grain threshers, grinders, winnowers, peanut shellers, corn shellers, circular saws, wood working lathes, water pumps, electrical generators, and a variety of small tools.

The contraption can be converted from the transportation mode to pedal power mode in a matter of minutes. The broad stand, which provides stability during power production, can be flipped upward during the transport mode and doubles up as a freight carrier. The power-generating device remains attached to the bicycle in transportation mode, so that it can be easily transported and used immediately. Of course, this pedal power unit is a compromise, but it is an interesting one. Contrary to modern concepts, it has a small flywheel and it does not use a friction drive because of its low efficiency. During the prime mover mode, the bike’s regular chain is slipped off of the chain-wheel, and a custom chain to the power take-off mechanism is slipped on. Changing gear ratios is as simple as it is on a road bike. For driving more powerful devices, a larger flywheel can be placed between the power module and the process unit.

Treadles

The many advantages of pedal powered machines don’t make hand cranks or treadles obsolete. Not all devices need the extra torque of pedal power. Hand cranks and treadles can be a better option if power requirements are low or if power is only needed over a short period. A hand cranked device is much more compact than a pedal powered device. If hand control is required while operating low power equipment, treadles remain the best choice because they offer the operator more freedom of movement than pedals.

Of course, both mechanisms can also benefit from advantages in modern design and materials – including speed or torque increasing gears. A good example is the R2B2 kitchen unit by German designer Christoph Thetard (which is not for sale, unfortunately). It combines three kitchen appliances with a central driving unit. The heart of the unit is a treadle powered flywheel which works as an short-term energy storage (as in the Human Powered Flywheel Motor), capable of delivering up to 350 watts (of mechanical power) to the appliances. Similar to late nineteenth century machines, and contrary to today’s kitchen devices, it is built to last.

Overheating

A stationary pedaller does not need to overcome air resistance. This sounds like a good thing, because at higher speeds a cyclist spends most of his energy compensating for air resistance. However, air resistance also keeps the active human body from overheating. It was found that the power output measured by ergometers (stationary bikes used to measure the power output of cyclists) is substantially lower than that produced by the same persons on the road because the absence of self-produced cooling winds, which results in possible overheating of the body (this is also a problem with velomobiles). A (self-propelled) fan could keep the stationary pedaller cool, but it is only a partial solution. As David Wilson notes in Bicycling Science:

The relative air flow generated by cycling is of such magnitude that it bears little resemblance to the drafts produced by the small electric fans often used for cooling people pedalling ergometers. At a speed of about 9m/s about 150 watts are dissipated into the air. Even if cooling fans of this power level were used negating the power production by the pedaller, the cooling effect would be much less than that for the moving cyclist, because most of the fan power is dissipated as air friction in areas other than around the subject’s body.

While body heat production might provide interesting side-effects in winter – you and even other people in a small room would not need heating – it would definitely limit the energy that can be delivered by pedal power. Pedalling outside when it’s windy may help, but this is not always possible. ←

Pedal powered mill thresher. Mayapedal.

Pedal powered machine with flywheel. Mayapedal.

Interchangeable thresher and degrainer. Mayapedal.

The Fender Blender. Rockthebike.com

Dual Purpose Bicycle. Job S. Ebenezer, Technology for the Poor.

R2B2: Treadle powered flywheel and kitchen devices. Christoph Thetard.

The Dynapod, designed by Alex Weir.

The Dynapod. Alex Weir.

Human powered flywheel motor. Image: J.P. Modak.

References

See: “The short history of early pedal powered machines”

Bike Powered Electricity Generators are Not Sustainable

The present approach to pedal power results in highly inefficient machines.

There are two ways to power a device by pedalling. You can power it directly through a mechanical connection – as was the case with all pedal powered machines for sale at the turn of the 20th century. Or, you can pedal to generate electricity, which is then used to power the device. In the 1970s, most research was aimed at direct mechanical power transmission. Today, the interest in pedal powered machines is almost exclusively aimed at generating electricity, for instance for charging cell phones and laptops – products that did not even exist in the 1970s.

With one exception (the Fender Blender, a pedalled powered machine to make smoothies), the only pedal powered machinery that is now commercially available in the western world (offered by Windstream, Convergence Tech and Magnificent Revolution) are stands to fit your bike to, connected to an electric motor/generator and a battery – a combination that can quickly convert your regular road bicycle into an electricity generator. These are also the pedal powered machines which are used for educational and arts projects, like powering a music concert, a cinema projection, or a supercomputer; or teaching kids the difference in energy use between, for instance, an incandescent light bulb and an energy saving lamp.

In an effort to raise awareness about energy use and global warming, the BBC even made a TV-programme in which an entire household was powered via pedal powered generators, with eighty cyclists generating up to fourteen kilowatts. These multi-person pedal power generators were pioneered in the 1970s by the Campus Center for Appropriate Technology (CCAT).

Energy Conversions

There are several problems with the present-day approach to pedal power. First of all, generating electricity is far from the most efficient way to apply pedal power, due to the internal energy losses in the battery, the battery management system, other electronic parts, and the motor/generator. These energy losses add up quickly: ten to thirty-five percent in the battery, ten to twenty percent in the motor/generator and five to fifteen percent in the converter (which converts direct current to alternate current). The energy loss in the voltage regulator (or DC to DC converter, which prevents you from blowing up the battery) is about twenty-five percent.

This means that the total energy loss in a pedal powered generator will be 42 to 67.5 percent (calculation example for highest loss: one hundred watt input = eighty watt after twenty percent loss in motor/generator = 57.5 watts after 25% energy loss in voltage regulator = 37.5 watts after 35% loss in battery = 32.5 watts after 15% loss in converter = 32.5 watts output = efficiency of 32.5% or energy loss of 67.5%). Furthermore, there will be an additional slight loss as the battery stands idle, and the charge efficiency (also known as charge acceptance or coulombic efficiency) of the battery will deteriorate over time. And to make the calculation complete, you should actually also include the energy loss in the electrical device that you are powering (we won’t do that here).

An energy loss of 42 to 67.5 percent naturally means that it takes 42 to 67.5 percent more effort or time to power a device (say, a blender) via electricity compared to powering the same device mechanically. This can be considered an acceptable loss if you are using a wind turbine connected to a battery as an energy source, but it becomes rather problematic when you have to deliver the energy yourself. If you produce one hundred watts of power and 42 to 67.5 percent is lost in the conversion, there is only 32.5 to 58 watts left to power the device. If you power the same device mechanically, you deliver a hundred watts straight to it. You thus have to pedal two to three times as hard or as long if you choose to take the intermediate step of generating electricity and storing it in a battery.

Not Made to Generate Power

The second problem with the present approach to pedal power is that it uses a traditional bicycle on a training stand instead of a pedal powered machine built from scratch – as was the case at the end of the 19th century. Of course, using a traditional bicycle has its advantages, but again it should be realized that this approach is considerably less efficient. One reason is the use of a so-called friction drive – the rear bicycle wheel acts upon the small roller of the motor/generator. While chain and belt drives (used in late nineteenth century pedal powered machines) have an efficiency of up to 98 percent, a friction drive is only eighty to niinety percent efficient (and wears much faster). This energy loss should be added to the 42 to 67.5 percent efficiency loss calculated above, which rises to 48 to 73.5 percent. Low tyre pressure will further decrease efficiency.

It should be noted that there is also energy loss in the bicycle itself: your pedals are not attached to the rear wheel itself. You turn a sprocket, which turns a chain, which turns a sprocket, which turns the rear wheel. So, on top of the efficiency loss of the friction drive should be added the efficiency loss of a chain drive (plus the energy loss in the derailleur, if your bike has one). Connecting a bike chain directly to the generator would prevent the energy loss of the friction drive, but it implies that you have to adapt the bicycle – destroying the whole concept of today’s commercially available pedal generators.

Additional energy losses can occur when using a road bicycle to generate electricity. For example, the picture accompanying the Windstream generator shows a racing bicycle. This is a bad choice, because the position of a rider on a racing bike is aimed to reduce wind resistance. Tests on ergometers (stationary bikes used to measure the power output of cyclists) have shown that pedalling in such a position is only about 80 percent as effective compared to a normal upright position, again resulting in considerable energy loss. On the road the rider position on a racing bicycle is beneficial because of the large importance of air resistance. However, on a stationary pedalling machine this position has no advantage whatsoever. The popular mountain bike is equally disadvantageous because of the corrugated tyres, which lower the efficiency of the friction drive. In short, while using a road bicycle to generate electricity has the advantage that you can use your own bike, this does not mean you can use just any bike.

Flywheel

Another important drawback of using a common bicycle is the absence of a flywheel – a heavy disc made of concrete, wood or steel that continues to generate power after it has been put in motion. In a pedal powered machine built from scratch, like the ones used at the turn of the twentieth century, the flywheel applies the function of the rear bicycle wheel in the training stand (although the flywheel is mostly placed at the front of the machine). The pedaller powers the flywheel, and the flywheel powers the machine (which can be a mechanical device or a motor/generator to produce electricity).

Why is a flywheel advantageous? Because there is an important difference between riding a bicycle on the road and pedalling a stationary machine. If we are pedalling, the power exerted by our feet on the pedals is inconsistent. It peaks every 180 degrees of crank rotation, and because the two cranks are placed 180 degrees out of phase this results in two power peaks per turn of the crank. Similarly, there are dead spots in between at the top and bottom position of the pedals (to be correct this minimum torque is not zero but about one third of the maximum). On a bicycle, this uneven exertion has little effect because of the inertia of both bike and rider. But on a stationary pedal powered machine, this natural pedalling rhythm results in jerky motion and additional stress on parts.

Because of its large mass and rotational speed, the flywheel evens out the difference between power peaks and dead spots. Evening out the power input means that the rider tires less quickly and can thus generate more power. The obvious disadvantage of a flywheel is that it is heavy – from ten to eighty kg for stationary pedal powered machines – and thus not exactly mobile.

The Battery

Generating electricity is not only inefficient, it also makes pedal power less sustainable, less robust and more costly. To begin with, batteries have to be manufactured, and they have to be replaced regularly. This requires energy, which can completely negate the ecological advantage of pedal power.

The embodied energy of a 150Wh lead-acid battery (like the one offered with the Windstream pedal power generator) is at least 37,500 Wh, which equals 250 full charges of the battery. In other words: if you can deliver 75 watts of power to the battery, you have to pedal for five hundred hours in order to generate the energy that was needed to manufacture the battery. Because the life expectancy of a lead-acid battery can be as low as three hundred discharge/charge cycles, you are basically pedalling to produce the energy required to manufacture the battery. If you also factor in the embodied energy of other electronics and parts, the ecological advantage of a pedal powered generator connected to a battery becomes rather doubtful. It might cost more energy than it delivers.

Of course, it also takes energy to manufacture a pedal powered machine that does not take the intermediate step of generating electricity. This concern lies mainly with the production of steel, and quite a lot of it. The commercially available Fender Blender mentioned earlier weighs 25 kg (55 pounds). If made from recycled steel, this comes down to an energy cost of at least 41,625 Wh, slightly more than the battery needed for the electricity generator. If freshly made steel is used, the embodied energy is at least 138,750 Wh (3.7 times the embodied energy of a single battery). However, these machines can last at least a hundred years (pedal powered machines surviving from the late ninteenth century are still in use), while the battery of the electricity generator has to be replaced every few years.

Resilient

While a pedal powered machine is the most robust and resilient energy source around if you power devices mechanically, this advantage is lost when you start generating electricity. Few people can manufacture batteries themselves, so you remain dependent on a regular supply of replacement batteries. Furthermore, the electronic parts of the machine (voltage regulator, motor/ generator, converter) can break down and are not easy to make or repair yourself either – contrary to old-fashioned pedal powered machines, which can be fixed yourself with readily available materials.

The extra components also make pedal generators more expensive. The commercially available models sell for seven hundred to more than one thousand dollars, not including the necessary replacements of the battery over time. Even if you make your own pedal power generator, the costs add up. The 2008 book The Human-Powered Home: Choosing Muscles Over Motors, which has plans for several kinds of pedal powered machines, estimates the costs of a DIY generator at about 50 (using scavenged parts) to $ 350 (using new parts), not including a bicycle stand and replacement batteries.

The mechanical pedal powered machines in the book can be built for ten to fifty dollars (the washing machine being more expensive at a hundred dollars), everything included. While the only commercially available mechanical pedal powered machine today is very expensive too (the Fender Blender sells for $1,700), the high cost is almost entirely due to the steel frame – which could be replaced by the frame of an old exercise bike, or built oneself from scavenged materials. Moreover, there are no additional costs for replacement batteries and the machine is built to last for a very long time.

Solutions

One way to solve the large energy losses of pedal power generators is not to produce electricity at all and power devices mechanically, whenever possible. Another way – the only way for devices that cannot be powered via a direct mechanical connection because they do not rely on rotary motion – is to make the generation of electricity more efficient. This can be done by building a pedal powered generator from scratch instead of using a road bicycle, and/or by ditching one or several electronic components in the power transmission chain. All approaches can be combined, resulting in a pedal power unit that can power a multitude of mechanical devices and generate electricity comparatively efficiently.

1. Build a Generator from Scratch

The best way to start is to build a pedal generator from scratch instead of using a bicycle on a training stand. This allows you to replace the friction drive by a more efficient drive, like a chain drive, and to add a flywheel. Steel flywheels can be found on the most expensive exercise bicycles. However, a flywheel can also be cheap, low-tech and just as efficient when you are using a bicycle wheel filled with concrete or a wooden tabletop. The latter is used by the Pedal Powered Prime Mover (PPPM) made by David Butcher, which is one of the few good examples of a pedal powered electricity generator built from scratch (the plans sell for $50 and the cost for the DIY version is estimated at $230). It consists of a steel frame made of steel shelving supports.

Although the PPPM uses a friction drive, it is a rather efficient one because it is basically powered by a wooden tyre – the flywheel. Since higher tyre pressure increases the efficiency of a friction drive, a wooden wheel can be considered a bicycle wheel with optimal tyre pressure. Furthermore, the flywheel is powered directly by the pedals, eliminating the energy loss in chains and sprockets altogether (it is a ‘direct drive’ in other words). The only drawback of this method is that you can’t change the gear ratio. Butcher (who built his first machine in the seventies) claims an improved efficiency of twenty-five to fifty percent compared to a standard bicycle on a training stand. Interestingly, it can also power some devices via a direct mechanical connection: a water pump, a hammer, a masonry chisel, an air compressor and a hack saw. Building a pedal powered machine from scratch can thus offer you the best of both worlds.

2. Ditch the Electronics

You can go much further in order to improve the efficiency of a pedal powered generator. In the most extreme case, you could skip the voltage regulator, the converter and the battery, which leaves you only with the energy loss of the generator. Or you can leave out either one of these devices. However, all these actions come with a price. If you do away with the converter, you need to replace the electrical devices you use. What you need, then, are DC-appliances like the ones you can plug in the interior of your car. While this can be an interesting option because of the high efficiency loss of a converter (twenty-five percent), not all appliances come in a DC-variant.

If you do away with the voltage regulator – and several of the pedal powered generators come without them – you have to carefully watch a multimeter while pedalling to make sure that the voltage does not exceed the capacity of the battery (or the device you are powering if you do away with the battery too). If not, you could destroy the battery (or the device, if you don’t use a battery). A flywheel can be of great help here, because it smooths out not only the energy input (the alternating high and low force of a natural pedalling rhythm) but also the energy output, keeping the voltage relatively constant.

3. Get Rid of the Battery

Doing away with the battery, or replacing it with a much more efficient and robust ultracapacitator, is probably the most rewarding thing you can do, not just in terms of efficiency, but also in terms of costs, reliability and sustainability. (Capacitators have a much longer service life than batteries, but a much lower energy density.) However, you lose the advantage of generating energy and storing it for later use. In this case, you would have to pedal while using the device at the same time, as is the case with direct mechanical power transmission.

Whether or not this is convenient is dependent on what you want to use your generator for. If you mainly want to charge your laptop or cell phone, not having a battery to store the electricity isn’t a problem since the devices themselves have one. However, if you want to light the staircase room or power a television, desktop computer, electric guitar or small fridge, this becomes rather awkward. If you want to play recorded music and dance, not using a battery would also be difficult.

4. Build Large-scale Pedal Power Plants

Improving the efficiency of pedal powered electricity generation becomes easier as you organise it on a larger scale. In most of the arts and education projects described earlier, like the BBC program or pedal powered concerts, no batteries are used. The key here is that it is not one person both generating and consuming power, but a large group of people, of whom some are producing electricity whilst others are consuming it.

Hypothetically, and in a similar fashion, electricity could be generated in large pedal powered electricity plants, and then distributed to houses, shops, public spaces and factories. This would be more efficient than doing it in each house separately because you can do away with the batteries and still offer electricity twenty-four hours a day. Power plants would simply add more pedallers when demand is high (such as during peaks hours) and send them home when demand is low (at night, for instance).

Human powered electricity plants should avoid the transmission losses of today’s extremely centralized power network. They should preferably be located in every neighbourhood or city district. In this scenario, it also becomes possible to do away with converters and switch the electricity distribution system from AC to DC, since the former was only chosen because it is more efficient to transport electricity over large distances. ←

David Butcher’s Pedal Powered Prime Mover addresses all problems of today’s commercially available machines.

References

See: “The short history of early pedal powered machines”

Insulation: First the Body, Then the Home

Modern thermal underclothing offers the possibility to turn the thermostat much lower without sacrificing comfort or sex appeal.

You could fill a library with reports and books describing the importance of energy-efficient heating systems and home insulation. However, not a word has been said or written about the energy savings potential of clothing, even though there has been a lot of progress in this area too. Modern thermal underclothing offers the possibility to turn the thermostat much lower without sacrificing comfort or sex appeal. The potential energy savings are huge; the costs are almost nil.

Space Heating

Over the last decades, both the insulation of homes and the energy efficiency of heating appliances have improved considerably. These efforts have led to substantial energy savings in fuel consumption. In spite of population growth, higher comfort levels, and a trend towards building larger homes, total energy consumption for space heating by American households came down from 5.32 quadrillion Btu in 1993 to 4.30 quadrillion Btu in 2005. Similar trends can be seen in other industrialized countries.

Nevertheless, space heating still consumes a huge amount of energy, which comes almost exclusively from fossil fuels. Moreover, these figures do not take into account the energy that was spent to demolish old buildings and build new, more energy-efficient homes. Research indicates that it can take thirty-five to fifty years before this embodied energy is recovered. This means that if a new, efficient building does not last that long, the result is more energy consumption, not less – though it will show up otherwise in statistics.

Further improvements in energy-efficient buildings and heating systems can be expected, but apart from the embodied energy required to make the housing stock more efficient, there is an additional problem that prevents a fast and steep reduction in energy consumption: cost. Home insulation and energy-efficient heating appliances are expensive, which means that many people simply cannot afford the investment. There is also the problem of split incentives: the owner of a rented house has no financial incentive to improve efficiency if the tenant is paying the heating bills.

Room Temperature

There is another way to reduce energy consumption for space heating that does not have any of these disadvantages: lowering the thermostat and putting on more clothes. Although room temperature is hardly ever mentioned as a factor in energy use, it is a decisive factor in the energy consumption of heating systems. Precisely how much energy can be saved by lowering the thermostat depends on the outdoor temperature. In temperate climates, lowering the thermostat just 1 °C (or about 2 °F) yields an energy savings of about 7 to 10 percent.

As far as I was able to find out, nobody has published a research report on the evolution of the average room temperature in winter throughout recent history. Today, the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) recommends an indoor winter temperature between 21 and 23 °C (70 to 73.5 °F). A Dutch report [4] mentions a rise in average winter indoor temperature from 20 °C in 1984 to 21 °C in 1992. David MacKay mentions an average room temperature of 13 °C (55 °F) in the UK in 1970. While these fragmentary data are far from sufficient to prove a rise in indoor temperatures, we can also count on the experience of many people who are old enough to remember that watching television in a t-shirt during winter is a relatively recent phenomenon. There seems to be no doubt that our comfort level has gradually risen because of better heating systems.

Note that the reduction in energy use for space heating thanks to more efficient homes was less than twenty percent from 1993 to 2005. Lowering the thermostat by 2 °C (or 4 °F) would thus result in energy reduction comparable to that. Turning down the thermostat from 22° to 18 °C would initiate an energy savings of at least 35 percent. And, as we shall see, significantly lower indoor temperatures are perfectly possible without sacrificing comfort.

The Body as a Heating System

When discussing space heating, we overlook the fact that our own bodies are heating appliances too. The human body’s core temperature is 37 °C (98.6 °F), and much of the skin’s temperature is around 33° to 34 °C (92 °F). Because the temperature of the environment is often lower than that, our body constantly emits heat into the atmosphere. A small percentage of this heat is lost through breathing, but the largest part of heat loss occurs via the skin. To limit this heat transfer from the skin to the environment, most mammals (and birds) are covered with hair (or feathers). Humans do not have this protection and this is why we have resorted to clothing ever since we left our origins in Africa (where it was hot enough to survive without additional layers of clothing).

Clothing does not produce heating by itself – it only prevents body heat from escaping into the environment. This happens by warming the layer of air between skin and clothing. Air is a relatively bad conductor of heat and therefore a good insulator. Exactly the same technique is applied when we insulate a home. The only difference is that in the case of a building we can use more rigid and bulky materials because a building does not have to move or feel comfortable. Naturally, insulation of the body is much more energy efficient than insulation of the space in which this body finds itself. Insulating the body only requires a small layer of air to be heated, while a heating system has to warm all the air in a room to achieve the same result.

Thermal Properties of Clothing: the clo

The insulating properties of clothing can be expressed in clo-units, where one clo equals the thermal insulation required to keep a resting person (for instance, a couch potato) indefinitely comfortable at a temperature of 21 °C (70 °F). The clo, which is of course derived from the word clothes, is not a standard international unit (the standard international unit of thermal resistance is m²K/W, where 1 clo corresponds to 0.155 m²K/W), but it has the advantage of being easily understood: one clo is equal to a man dressed in a three-piece business suit (shirt, trousers, suit jacket) and light underclothes. Burton, who defined the clo-unit, wrote in 1946:

We found that we could explain even to a General or Admiral, without a course in physics for which he had neither the time nor patience, that his uniform had about one clo-unit of thermal insulation, his greatcoat another one clo-unit, and that together they provided him with a total of two clo-units.

In Europe, a similar value was developed called the tog (British slang for clothes), which equals 0.645 clo. Both values can be compared to the R-value of building insulation materials, where 1 clo equals 0.88 R (or 1 R-value equals 1.137 clo). The clo is more commonly used than the tog, so we will stick to the American unit here. Clo-values are calculated by means of a thermal manikin.

Maintaining Thermal Comfort

The clo is an interesting unit because it allows us to precisely calculate which clothes we have to wear to feel comfortable at any given indoor temperature. According to the Encyclopedia of occupational health and safety, the required clo-value to maintain a neutral thermal sensation rises to about 2.7 at an indoor temperature of 10 °C (50 °F). When the indoor temperature drops to 0 °C (32 °F), the required thermal insulation rises to 4 clo. As a rule of thumb, each change of 0.18 clo units compensates for a 1 °C change in air temperature (according to the ASHREA).

Alternatively, we can calculate the clo-value of any given piece of clothing and of any given clothing ensemble. The ASHREA, the ISO and some other research teams have compiled overviews that list hundreds of individual clothing pieces with their corresponding clo-values (see sources). A t-shirt with short sleeves has a value of about 0.10 clo, while a sleeveless undershirt offers about 0.06 clo. Knickers add about 0.20 clo. A short-sleeved shirt has a clo value of about 0.15 to 0.25, while a long-sleeved shirt offers about 0.20 to 0.30 clo.

Long-sleeved sweaters offer 0.20 to 0.40 clo, trousers offer 0.25 to 0.35 clo, and a long skirt or robe 0.22 to 0.77 clo. Briefs add a thermal insulation of 0.05 clo, while socks add 0.04 to 0.10 clo. Long underwear offers 0.20 to 0.35 clo for the upper as well as the lower part. All these values can simply be added to calculate the total clo-value of a clothing ensemble. An alternative method is to measure the thickness of a clothing ensemble: every layer of 2 centimetres results in an approximate 1.6 clo-value.

Clothing Insulation and Room Temperature

From these data, it can easily be demonstrated how even slight changes in clothing insulation can have a profound impact on heating costs and energy use. A person wearing briefs (0.05 clo), light socks (0.05 clo), a t-shirt (0.10 clo), a heavy shirt with long sleeves (0.25 clo), a sweater (0.30 clo) and long pants (0.30 clo) is protected by a total thermal insulation of 1 clo, meaning that this person will remain comfortable hanging out in front of the television at a temperature of 21 °C(70 °F). However, without the heavy shirt and sweater, this value drops to 0.55 clo. This means that watching television wearing just a t-shirt requires an air temperature of 24 °C (75 °F) in order to maintain thermal comfort. This would lead to a rise in energy consumption of 20 to 30 percent.

On the other hand, if this person combines his original ensemble (including heavy shirt and sweater) with a full set of long underwear, the clo-value rises up to 1.7, allowing the temperature to drop to about 17 °C (63°F), saving 30 to 40 percent on heating costs and energy use compared to the normal winter outfit, and saving 50 to 70 percent on heating costs and energy use compared to the outfit with only a t-shirt on the upper body.

When we’re talking about common clothing, raising the clo-value of an ensemble basically comes down to adding more weight in clothes. A general rule of thumb is that the clo-value equals 0.15 times the clothing weight in pounds. Wearing 6.6 pounds (3 kg) of garments thus equals 1 clo. The relationship between thermal comfort and clothing weight explains why we tend to prefer a higher air temperature to adding more clothing. If we would like to stay comfortably warm at an indoor temperature of 0 °C (4 clo), we would have to wear 26 pounds (12 kg) of clothes. The US Army found in the 1960s that a maximum of 4 to 5 clo-units could be worn for a man to remain mobile and dexterous enough for military tasks. Additional clothing weight thus limits our freedom of movement, and even couch potatoes have to get up from time to time.

However, things have changed. The military, space agencies and the sports clothing industry have considerably improved the warmth/weight ratio of clothing over the last decades. This has resulted in a very diverse and fashionable line of lightweight clothes with high clo-values. A great deal of this progress is due to the use of new, synthetic materials. While these have been used for all kinds of garments (sweaters, pants, jackets), their importance for indoor use is especially relevant in the case of long underwear. This clothing layer (which is actually worn in combination with briefs) has the largest potential to substitute a heating system.

Thermal Underwear

Because it fits tightly around the body, long underwear has an optimal pumping coefficient. The pumping coefficient is another factor that defines clothing insulation, in addition to the clo-value. It refers to the motion of air produced by wearer movement. Even couch potatoes move from time to time, and this activity can disturb the insulating air layer around the body, degrading thermal comfort at least temporarily. The pumping coefficient is much better for long underwear than for loose-fitting garments such as ponchos, wide pants, or thick knitted sweaters, so long underwear offers more thermal comfort even when clo-values are similar. Another factor is the chimney effect: even without wearer movement, loosely hanging clothes ventilate the trapped air layers, thus reducing insulation.

Long underwear has more advantages over other clothing options. It does not hide your body shape and can maintain sex-appeal, a common concern for both men and women. It can easily be worn underneath normal clothing. And, last but not least, it can be worn in layers, further improving upon the insulation value: more air is trapped using several thin layers than by a single, bulkier layer. According to the US Air Force Survival Book, one layer of long underwear (long pants + long-sleeved t-shirt) equals a clo-value of 0.6, while two layers of long underwear add a clo-value of 1.5. In other words, the clo-value more than doubles by using two layers. Combine this outfit with a typical business suit (or a similar, more comfortable clothing ensemble), and thermal insulation rises to 2.5 clo, enough to keep a couch potato indefinitely comfortable at a temperature of only 12.7 °C (55 °F) – far below the common indoor temperatures of today. This clothing ensemble could yield a reduction in energy use for space heating of up to eighty percent.

Unfortunately, the clo-values of modern thermal underwear have not been listed in well-documented overviews, as is the case for more common clothing options. Nevertheless, fragmentary information points to considerably higher clo-values than those for traditional long underwear. Calculations by well-informed amateur hikers show clo-values that are at least double those of the long underwear mentioned by the US Air Force (for instance, 0.66 clo for the upper piece alone). This would mean that the same thermal comfort could be achieved using only one layer of long underwear plus the equivalent of a winter business suit (2.5 clo at 12.7 °C), or that using two layers plus the suit could bring the comfort level for a resting person down to a temperature of 0 °C (wearing 4 clo of clothing).

Another indication for the additional energy savings potential of high-tech long underwear are the clo-values of different materials. According to the Handbook of technical textiles, the warmth/weight ratios of pile fabrics like polyester and acrylic are 2.5 to 8 times higher than those of woven and knitted fabrics like wool or cotton (materials used for traditional long underwear). Quilt battings like Thinsulate offer warmth/weight ratios that are 13 to 17 times those of cotton and wool.

Synthetic or Natural materials?

Synthetic clothes are made from fossil fuels. When the clothing is used as a substitute for a heating system, the energy saved by lowering the thermostat is much larger than the energy required to manufacture the garments. Synthetic long underwear has a higher insulation value than many natural materials, it is more durable, and it can be very cheap. Nevertheless, there are disadvantages compared to natural materials: plastic fibre pollution, high fire susceptibility, and a tendency to attract dirt. Synthetic thermal underwear should be washed regularly – a process that consumes energy.

Synthetic clothes are not a necessity. Even the use of long underwear made from natural materials like cotton and wool has the potential for considerable energy savings. Cotton might have a relatively low insulation value, but a full layer of cotton long underwear will still add at least 0.4 clo to your thermal comfort – enough to lower the indoor temperature by 2.5 °C and save more than twenty percent on heating bills. Using wool can more than double this potential to about 1 clo for a full layer of long underwear (allowing for an indoor temperature reduction of more than 6 °C).

Wool made a comeback as a material used for hiking and mountaineering clothes in the mid-1990s, at which point Icebreaker was the first manufacturer to position itself in the market with woollen thermic underwear. The company uses wool from the merino sheep in New Zealand, which produce some of the finest and softest wools available. Patagonia also offers a series of merino wool underwear, and several European manufacturers (Mammut, Woolpower and Helly Hansen) mix merino wool with synthetic materials. This leads to more durable clothing – wool wears out much faster then synthetic materials. An important advantage of wool over synthetic (and over other natural) materials is that it maintains a good smell for a very long time. Regular washing is not required. The largest disadvantage of merino-wool is the price: you won’t find a full set of long underwear for less than 200 euro. But again: this investment will quickly pay for itself if it allows you to lower the thermostat.

Thermal Comfort

Thermal comfort is not just dependent on air temperature and the thermal insulation properties of clothing alone. In fact, more than a dozen other factors – both personal and environmental – play a role. However, environmental factors are of much less relevance for indoor thermal comfort than for outdoor use. Indoor clothing does not have to be windproof, waterproof or be able to wick away perspiration. After air temperature, the environmental factors influencing thermal comfort are the mean radiant temperature, relative humidity and air movement. The last two are included in the clo-value, which is defined in an environment with a relative humidity of less than 50 percent and an air speed of 6 metres per minute (stagnant air).

Wind has a profound influence on the thermal insulation of clothing when we are outdoors because it disturbs the insulating air layer between skin and clothing. Indoors, air movement is mostly a negligible factor, although it should be kept in mind that any draft can lower the thermal comfort of a clothing ensemble. Radiant heat is another major influence on thermal comfort when we are outdoors. The radiant heat of the sun can make you feel hot even when air temperature is low. Indoors the influence of radiant heat is much less. Nevertheless, it can have a positive influence on indoor thermal comfort, because sunlight that enters the room will be absorbed by walls and furniture, and gradually released. This is especially so in passive houses and in homes heated by a tile stove, where radiant heat is an important factor in thermal comfort.

Along with the clo-value and the pumping coefficient, the third factor defining the thermal insulation of clothing is the permeability index. The thermal properties of clothing drastically degrade when they become wet, either by sweating or by external moisture. This can be very dangerous if you are physically active in a cold outdoor climate because during a resting period your body can quickly lose heat, possibly leading to hypothermia and death. But of course, the permeability index is not of any importance for indoor couch potatoes: they don’t sweat. Indoors, rain is not a concern either.

Human Activity Indoors

The most significant factor influencing thermal comfort – even more important than air temperature and clothing – is human activity or body heat production (the metabolic rate). For instance, while it takes twelve clo-units to keep a resting person warm at an extremely low temperature of minus 40 °C, this comes down to only 4 clo when this person is walking, and to only 1.25 clo when this person is running at 16 km/h. One of the most obvious reasons why our forebears could bear lower indoor temperatures, was that they were more physically active than many of us.

It is telling that one defence mechanism of the body against cold is to increase its heat production. This happens first by muscle tensing and ultimately by shivering, which can increase body heat production by up to five times (from 100 watts at rest to about 500 watts). The metabolic rate also has a profound influence at non-extreme temperatures. While a resting person (like a couch potato) requires a thermal insulation of 2.7 clo at an indoor temperature of 10 °C (50 °F), this is lowered to only 1.7 clo when this person is engaged in very light activity (like typing, drawing or having an animated conversation).

In this case, the combination of long underwear with the equivalent of a typical business suit suffices to keep him or her warm. As a general rule of thumb, each increase of 30 watts in heat production allows the comfort temperature to go down by about 1.7 °C. On the other hand, when sleeping instead of just resting, the required thermal insulation approximately doubles – for instance to 2 clo at a temperature of 20 °C. This is why sleeping bags can have thermal insulation of more than 10 clo-units.

Personal factors other than clothing or activity can also contribute to thermal comfort. Men seem to tolerate lower temperatures than women, and both small children and the elderly need higher temperatures to sustain their thermal comfort. Research has shown that – even regardless of age and gender – different people prefer slightly different ideal temperatures. Furthermore, people also get used to prevailing temperatures, leading to clearly observable cultural differences. The clo-values given for different indoor air temperatures are thus not more than guidelines – personal differences will occur.

Hands and Feet

The clo-value refers to the whole body surface and thus includes heat transfer by exposed body parts (head and hands, in some cases also arms, legs, feet or torso). Both the clothing insulation and the skin coverage are important determinants of heat loss. In real life the two are correlated in the sense that winter clothing not only insulates better, but also covers a larger proportion of the body than summer wear. Hands and feet are always the first victims when thermal discomfort sets in. Together with the head and the neck, they lose more heat than other parts of the body.

However, it is important to note that if the body as a whole is kept warm enough, hands and feet will not be greatly affected by lower indoor temperatures. Cooling down the extremities is yet another defence reaction of the body if the core temperature falls. This thermoregulatory mechanism – vasoconstriction – reduces the blood flow to the skin, improving skin insulation and thus limiting heat loss. It happens all over the body, but due to their small mass and large surface area, vasoconstriction has the most profound effect on the hands and the feet. At extreme cold temperatures, vasoconstriction can save your life – though it might cost you some fingers and toes, or worse. In order to maintain body core temperature (which is vital for survival), the body will sacrifice hands, feet and nose first, followed by the limbs. Because vasoconstriction only occurs when the core body temperature falls, it won’t happen if you’re dressed warmly enough. While insulating your neck and feet will greatly improve your thermal comfort, there is no need to wear gloves or caps indoors.

In fact, it doesn’t matter very much which parts of your body you choose to insulate – the important thing is to limit total heat loss so that the body core temperature remains stable. For instance, if you prefer to wear a high-insulating cap indoors, you can pretty much forget about all the rest and be comfortable in relatively light clothes at low temperatures.

Life without Heating?

Of course, this article is not a plea to get rid of heating systems altogether, although in some climates this is clearly possible – saving not only heating costs but also the instalment of a heating system and other investments. However, for many of us, a heating system remains a necessity, if only because temperatures regularly drop below freezing point (water pipes would freeze over, and keeping full thermal comfort by clothing alone will become difficult). But even then, thermal underclothing could lead to an important reduction in energy consumption by making it possible to lower the average indoor temperature a few degrees and to shorten the heating season by a couple of months.

The energy savings potential of clothing is so large that it cannot be ignored – though in fact this is exactly what is happening now. This does not mean that home insulation and efficient heating systems should not be encouraged. All three paths should be pursued, but improving clothing insulation is obviously the cheapest, easiest and fastest way. One final disadvantage is that visitors not wearing thermal underclothing will feel uncomfortable at your place, even if you and your family are feeling all right. Offering casual visitors an extra layer of thermal underwear might not always be an option. ←

Clothing insulation for different types of outfits. From Work Design, Stephan A. Konz, 1979.

References

The Empty Homes Agency & BSHF (2008), “New tricks with old bricks. How reusing old buldings can cut carbon emissions”, EHA publishing, March 2008.

U.S. Energy In formation Administration, “Winter Energy Savings from Lower Thermostat Settings” (2000), EIA Independent Statistics and Analysis (website). http://www.eia.doe.gov/emeu/consumptionbriefs/recs/thermostat_settings/thermostat.html

Uitdenbogerd, Diana & Vringer, Kees (1999). Energy reduction options for the domestic maintenance of textiles. Wageningen: Wageningen Agricultural University, Household and Consumer Studies.

Jeeninga, H. (1997). “Analyse energieverbruik sector huishoudens 1982-1996. Achtergronddocument bij het rapport ‘Monitoring energieverbruik en beleid Nederland’”, Energie Centrum Nederland Beleidsstudies, December 1997.

“The best clothing combinations for backpacking or hiking?” (Forum thread, 2007), Backpackinglight (website, 2001). https://backpackinglight.com/forums/topic/9378/.

Research Study Group 7 on Bio-medical Research Aspects of Military Protective Clothing (1988). Handbook on clothing: biomedical effects of military clothing and equipment systems. (s.l.): The Group.

McCullough, E. A (1985). A comprehensive data base for estimating clothing insulation. (s.l.): ASHRAE.

United States Air Force (2008). U.S. Air Force Survival Handbook. New York: Skyhorse Publishing, Inc.

Meyer, Alan (1994). “Some like it hot”, Home Energy Magazine, March/April 1994.

Horrocks, A. Richard & Subhash C. Anand (2000). Handbook of technical textiles. Vol. 1, Oxford: Woodhead Publishing.

Adam, J. M. & J. D. Walters (1969). “Climate and clothing” (meeting June 6, 1968), Proceedings of the Royal Society of Medicine, Vol. 62, No. 3, pp. 275-277.

Stellman, Jeanne Mager & Robin Mary Gillespie (1998). Encyclopaedia of occupational health and safety.

Gilligan I. (2007). “Clothing and modern human behaviour: Prehistoric Tasmania as a case study”. Archaeology in Oceania. Vol. 42, No. 3, pp. 102-11.

HVAC Handbook - thermal comfort by INNOVA (2010).

McArdle, William D., Frank I. Katch & Victor L. Katch (1994). Essentials of exercise physiology. Philadelphia: Lea & Febiger.

ISO 9920 international database (2007). “Ergonomics of the thermal environment - Estimation of thermal insulation and water vapour resistance of a clothing ensemble” (standards catalogue)

This seems to be a more recent list of the clo-values for common clothing pieces. I did not consult this document because I find it too pricey (+ 200 dollars). If anybody has access to it, comments are always welcome.

Textiles Intelligence Ltd. (2007). Temperature control fabrics, finishes and materials: optimising wearer comfort. Wilmslow, United Kingdom: Textiles Intelligence Limited.

This report might have more accurate data on the clo-values of modern long underwear. I did not consult it because of the high price (325 euro).

Kent, Michael (2006). The Oxford dictionary of sports science & medicine. Oxford: Oxford University Press.

Aerial Ropeways: Automatic Cargo Transport for a Bargain

Cargo tramways can be fully or partly powered by gravity, and some deliver excess power that can be utilized to generate electricity or to drive cranes or machinery in nearby factories.

These days, we use them almost exclusively to transport skiers and snowboarders up snow slopes, but before the 1940s, aerial ropeways were a common means of cargo transport, not only in mountainous regions but also on flat terrain, with large-scale systems already built during the Middle Ages.

Monocable and Bicable Systems

Before we start, it is important to note that aerial ropeways (also known as aerial tramways or cableways) can be divided in two groups: monocable and bicable mechanisms. In a monocable system, one endless rope serves to both support and move the carriers in transit. In a bicable (or tricable) system, separate ropes sustain these functions: one or two static support ropes, the carrying ropes or track cables, and one or two light travelling haul ropes.

Ancient and medieval ropeways were of both variety, while modern ropeways (from the 1850s onwards) were initially exclusively monocable systems. Later, bicable systems took over almost completely. At the end of the 19th century, both ropeway methods were also applied to canal transportation, with monocable systems used for cable trains. Bicable mechanisms are much better suited if the track spans larger distances and/or has steeper grades.

If only one endless rope would be used on a track which includes a long span or a steep grade, it would become necessary to make the entire double length of the moving rope strong enough for the special strain that appears on that spot. Increasing the size of the rope affects the dimensions of the supports, sheaves and other fixtures throughout the line, adding to the costs. In a bicable system, the stationary carrying cable can be locally graduated to the strains it has to bear.

Ropeways in Ancient Times

Ropeways have been used for more than 2,000 years, transporting both passengers and goods. The first sign of their use comes from the rugged Asiatic countries of China, India and Japan, where it is speculated that they may have been in operation since 250 BC. People used rope to cross ravines, rivers and river-gorges, initially transferring themselves, hand over hand, with the body suspended by a crude harness. The harness eased the load and allowed a rest as the loop was slid along the rope track.

The next application was to pull oneself back and forth in a basket or cradle, usually with a few belongings in tow. This was made possible by means of thinner cords fixed to the front and the back of the basket, or by gravity in case the arrival point was at a lower height than the starting point. The empty sling or basket was then drawn back to its original position by a smaller cord attached to the back as before.

Sometimes, the rope was threaded through a hollow piece of bamboo before being attached, so that the person could slide down the rope without burning his or her hands. All that was needed to build a ropeway was a rope, knots to tie the rope to a rock or tree or anchor on both sides, and a bow and arrow to shoot the rope across. After the invention of the crossbow by the Chinese, heavier cables could be shot over longer distances. Sometimes the rope was supported on simple wooden trestles.

Ropeways were also used to transport pack animals. Inversely, pack animals were sometimes used to pull the ropeway. These early aerial ropeways were the forerunners of later technologies such as the suspension bridge and the elevator. They were also the closest approach to aerial navigation at the time.

Ropeways in the Middle Ages

One of the first mentions of ropeways in medieval times appears in the Taiheiki, a Japanese historical epic written in the late 14th century. It relates how a Japanese emperor escaped via ropeway over a valley when surrounded by enemy forces. In Europe, initial reference to the use of ropeways can be found in Bellifortis, a weapons catalogue from 1405. A 1411 book is the first to show a drawing of a ropeway. Between 1411 and 1440, when technologies such as water mills, windmills and harbour cranes became more popular, references to both monocable and bicable operations increased. In South America, aerial ropeways to transport gold have been reported as far back as 1536.

The 17th century saw an increase in design sophistication. Venetian Fausto Veranzio illustrated a refined bicable passenger ropeway in the Machinae novae, published in 1615 and 1617. It consisted of a wooden box in which the passengers rode, travelling on pulleys over a fixed rope. The vehicle was propelled over the river by the occupants pulling themselves along by means of this slack loop.

Dutchman Wybe Adam erected a successful large-scale operational system in 1644, which is described in the Danzig Chronicles. Adam engineered a continuously circulating ropeway to carry the earthworks material in baskets for a hilltop fortress in Gdansk/Danzig. Ropeways were also constructed by monasteries built high on pinnacles, where they were used to lift supplies and visitors.

Ropeways From the 1850s Onwards

From about 1650 to 1850, no further progress was made. The technology had reached its maximum potential at the time, limited by the strength of the available ropes. This all changed with the arrival of the much stronger wire rope in the mid-nineteenth century, which led to the most successful period of aerial ropeways in history. Another breakthrough was the standard coupling designed in the early 1870s by the Austrian von Obach, which allowed the cars to be disengaged and reattached to the trackway. Last but not least, new power sources appeared: first steam engines, then electric motors.

Until the end of the nineteenth century, aerial tramways had been powered by humans (sometimes using a windlass or a treadwheel), by animals (mostly gins worked by horses or mules), by waterwheels and/or by gravity. The last option was (and is) only available in mountainous areas: the descending carriers deliver all or part of the necessary power to haul up the ascending carriers. If the descending cargo is sufficiently heavier than the ascending cargo, and the angle of descent is great enough, the ropeway could be kept running without any additional power input, making it a full-fledged zero emission transport mode. The speed of the descending carriages was governed by means of hand or water powered brakes.

Even when the ascending load was heavy, gravity could be used to transport cargo up the mountain; where water was available at the highest point of the ropeway, it was possible to run materials up alone, employing the descending carrier as a counter-balance filled with water. The system is reminiscent of those used by some early 1900 cable trains.

Net Producer of Energy

In some gravity powered lines, where the surplus power delivered by the descending cargo was larger than the power required to haul up the ascending carriages, the cableway could be a net producer of energy. Power could be taken off at any point along the track and utilized to drive nearby machinery, for instance driving ore crushers, pumps or sawmills. A ropeway thus offered the additional possibility of powering neighbouring factories solely by gravity. Before the arrival of electricity, this excess energy was transmitted by mechanical means (wire ropes). Present-day cargo ropeways (see further below) use the excess power to generate electricity.

The introduction of electricity as a power generator did not make aerial ropeways unsustainable – far from it. An electrically powered aerial ropeway is one of the most efficient means of transportation available. It offers all the advantages of electric transmission (energy-efficient, relatively silent, power can be produced by renewable sources) while eliminating the many problems that come with batteries and charging stations (as is the case with electric cars). In mountainous regions, the electric motor can be assisted by gravity power from the descending carriers, further improving efficiency.

Furthermore, an aerial tramway offers some additional benefits in power consumption compared to other sustainable options such as cargo trains, cargo trams (streetcars) or trolleytrucks. Firstly, energy delivery is more efficient with a fixed electric propulsion system in a single terminal than with transmission over large distance by wire. Secondly, because there is no interference with surface traffic, a constant speed can be maintained, again improving energy efficiency.

Applications of Cargo Ropeways

Comparatively, few aerial ropeways were built for passenger transportation at the turn of the 20th century, where their primary function was solidified as a means for cargo transportation. Applications were many and diverse, and they occurred all over the world.

There is no information to be found on the total amount of ropeways that were once in existence, but some sketchy bits of data give us an idea. A source from 1899 names 900 aerial ropeways of a certain technical type in operation worldwide. A product catalog from 1909, still well before the heydays of cargo ropeways, names a figure of 2,000 ropeways worldwide of a certain brand (the Bleichert system), aggregating over 1,300 miles in length and transporting 160 million tons annually. Evidently, this was not an obscure technology.

Warfare

Early modern ropeway technology was led by the Europeans, particularly Germany and the Alpine countries – Austria, Switzerland, France and Italy. Aerial ropeways were extensively used for warfare in the Alps between the early 1900s and 1945. Italy used ropeways in the war against Turkey in 1908. During World War I and World War II, aerial ropeways were widely used in the mountain battles between Italy and Austria. Almost 2,000 ropeways were operated by the Italians and over 400 by the Austrians, with most of them being portable.

They could quickly be disassembled, moved using pack animals, and assembled somewhere else. Military ropeways were used to reinforce difficult terrain with troops, supplies, howitzers, ammunition and fortification building materials. They were also a short term solution for destroyed bridges and other water crossings, or to lower casualties to hospitals in stretcher carriages.

Mining, Agriculture, Construction

Many cargo cableways were utilized for mining purposes – the first ropeways in the US were for transporting materials when mining in the West was booming. There are many references to ropeways that carried ores (gold, silver, iron, copper), coal, stone, slate, clay, sand, granite, quartz, lime, phosphate rock and brownstone. These goods were usually transported from the mine to a crusher, a railway, a ship or (in the case of coal) a steam engine. Terminals could be set up on a short section of rail, and gradually moved towards the other terminal as the material was removed from before it.

Another important application was the carriage of agricultural products: fruits (like bananas), cereals (like wheat), and other plantation produce like cotton, tea-leaf or sugar cane. These goods were mostly transported from the fields to a mill or railway station. Aerial ropeways were in use on sugar plantations in Demerara, Jamaica, Mauritius, Martinique, St. Kitts, Guatemala, Australia and elsewhere, for the delivery of canes to the crushing mills.

A special arrangement was extensively adopted in Mauritius: several wire ropeways driven from the same point discharged on the same cane carrier. A great advantage was that the canes were delivered in a continuous stream direct onto the cane carriers and in quantities that were at no time large enough to demand redistribution in feeding the mill – somewhat similar to today’s just-in-time principle. Only one man took care of the discharge of the carriers. In many cases an agricultural ropeway was employed in combination with cartage, the canes being brought to certain points along the line by the carts. Ropeways were used for the carriage of beetroot to the sugar factories, in Holland for instance, where the system was used on flat land.

The technology was popular for the transport of wood and wood products: logwood, cordwood, sawed timber, charcoal, wood pulp, paper pulp and paper. These were usually transported from a forest to a sawmill or from a sawmill to a railway station. Aerial tramways were applied by builders to convey bricks and materials to the desired points. A ropeway could carry cement from the kilns to the works, and the empty carriers could be used for conveying up coal to the kilns.

Factories

Another application was the transport of materials within factories – this could be anything, from manufacturer’s supplies, to refuse, materials in process of manufacture, merchandise of all kinds, and particularly products requiring careful manipulation, such as explosives, liquids or glassware. The ropeways in factories were generally short, and the cables could be frequently supported at many points from brackets fixed to the walls of adjacent buildings, saving costs.

Ropeways were in operation in many print works, linoleum works, mills and other factories. Examples were at artificial manure works near London (the line passed over buildings, dwelling-houses and yards full of workmen) and linoleum works near Middlesex (where the line – driven by water power – passed over a river and many of the workshops and roofs).

Ropeways were used for connecting lines of railway at opposite banks of rivers where bridge building would be unduly costly or difficult. One of these lines was constructed to pick up wagons with their loads, traverse and put them on track at the other side and vice versa. On a much smaller scale, at the end of the 19th century, miniature wire ropeways were introduced in shops for transporting cash.

Harbours

In manufacturing establishments, cableways were operated to distribute material taken from boats or cars to certain storing places in the yards. Aerial ropeways were used by ship owners for the loading and unloading of their cargoes and/or for the bunkering of fuel (coal for the steam engine). Ropeways provided a means of forming piers for loading and discharging materials when ships and lighters were forced to lie at some distance from the shore because of the shallowness of the water.

One of these ropeway piers, at the Cape Verde Islands, measured 1200 feet (365 metres) in length, of which 960 feet extended along the beach, and about 240 feet at right angles to the longer section to the end of the pier, where the coal was received and dispatched. The ropeway carried 15 to 25 tons per hour in either direction, and the motion of the rope was also utilized in working cranes at each terminal for raising or lowering coal. All this was powered by a 16 HP steam engine. The erection of the site took a mere three months. Similar installations were built in New Zealand and South Africa. Aerial ropeways were also tested to transport coal between ships on the sea.

For every material carried by a tramway, there was a specially designed carrier receptacle. This was the case for – among others – or minerals, produce, manure, coke, sacks of flour, textile goods (protected from the weather), cement, petroleum, wine and beer. Some of these carrier receptacles were unloaded by striking a catch, causing the bottom to open or the whole receptacle to capsize or tip up. Loading was mostly (though not always) done by hand.

Length, Speed and Capacity of the Lines

Length and capacity of aerial tramways gradually increased throughout the century. In 1911, aerial ropeway lines were typically 1,000 to 15,000 feet (305 to 4,600 metres) long, with a daily cargo capacity of 15 to 200 tons and speeds of around 2 to 5 mph (3,2 to 8 km/h). Some gravity powered installations were faster, with speeds around 15 to 30 mph (24 to 48 km/h), but higher speeds were considered to be a negative influence on wear and tear. Weight of the individual loads varied from 25 to 375 kilograms.

Motive power, if applied, was generally from about two to fifteen HP. The fall was between zero (almost horizontal lines) and 4,000 feet (1,220 metres). Working staff amounted to two to five people. Some lines were built parallel to each other in order to increase cargo capacity (the maximum capacity of a single ropeway was about 800 tonnes per day). Some early ropeways were longer and more powerful. The Usambara ropeway in Africa was 5.6 miles (9 kilometres) long and transported tree trunks weighing up to one tonne each. At its highest point, the ropeway was 130 metres above the ground.

The Garrucha ropeway, an installation at iron ore mines in Almeria, Spain, was 9.75 miles (15 km) long. The construction of the line took only 6 months. It had a daily transport capacity of 420 tons (working ten hours per day), powered by a 100 HP engine. Similar tramways were built in mines in Basque country, north-western Spain. The Transylvanian wire ropeway, an installation at blast furnaces in Hungary transporting charcoal and ore, was nearly 19 miles (30,6 km) in length, and had a fall of almost 3,000 feet (915 metres). Capacity was around 800 tons per working day. A ropeway in Argentina, in operation from 1906 to 1927, was 21.3 miles (35 km) long.

The 1920s saw the construction of even longer ropeways. The longest in Europe was the line erected in 1925 in Granada, Spain. It was used to carry goods from the city to the harbour in Motril over a distance of 39 kilometres. The infrastructure consisted of 240 towers and seven stations. The 300 vehicles with a loading capacity of 700 kg each travelled at a speed of 3 metres per second. After the ropeway was built, the port of Motril quickly attracted more traffic. In 1929, an additional 200 vehicles were added to the line. Interestingly, the Granada ropeway was a public service – anybody and everybody could make use of it. Operations ceased in 1950, following the demise of local industry and agriculture.

The longest cargo tramway in the world during the 1920s was used for the transport of coffee from Manizales to Mariquita, Colombia. More than 800 vehicles travelled on the 72 kilometre line (45 miles), which was supported on more than 400 towers. The ropeway was opened in 1923 and remained in service until 1961. The 1930s and 1940s saw the construction of the longest ropeways ever built. The Swedish Forsby-Köping limestone ropeway was the longest in Europe at the time of construction (42 km or 26 miles, in operation from 1939 to 1997), but this record was beaten by the 96 km (60 miles) long Norsöj aerial tramway, also in Sweden. It had 514 towers and 25 tension stations.

This tramway, which was in operation from 1943 to 1987, was built in just 370 days and is the longest cableway ever constructed. The Massawa-Asmara ropeway in Eritrea, built by the Italians, was 75 km (46.5 miles) long and was used from 1937 to 1941. In 1959, a 76 km long cableway with 858 support towers started operation in the Republic of Congo. It remained in use until 1986, operating 24 hours per day.

Transport Infrastructure

Ropeway towers could be constructed from timber or iron and were generally between 100 and 300 feet (30 to 90 metres) apart, although much longer spans were possible if necessary. In bicable ropeways the tension in the track cables was produced by weights applied at one of the terminal stations. However, in longer lines it became necessary to apply additional tension at intermediate points. For this purpose tension stations were built at distances of about 3000 to 6000 feet. The cars passed from one section of the cable to the next by means of intervening rails – so that no interruption occurred in the continuity of the track. This means that there are no limits to the length of a ropeway: each (longer) ropeway consisted of multiple sections that could be considered as separate ropeways.

The same technique was applied to angle stations, which were used to make a curve in a ropeway (tension stations and angle stations could be combined). The largest drawback of an aerial tramway, also relevant today, is that it can only be built in a straight line. Every angle in a ropeway requires the erection of an angle station, which raises capital costs. However, in general, few angle stations are needed because ropeways can be constructed above most obstacles. Moreover, each tension and/or angle station can also double as a loading or unloading station. Goods could even be sent along different routes via a switch if more ropeways met at a single point. To guard against the risk of accident from the premature discharge of a bucket or other cause when crossing public highways or railroads, wire nets were usually suspended between supports on either side, or structures especially erected for the purpose.

Installing a Ropeway

Instalment of ropeways in the mountains was not an easy task. The long rope was usually shipped on reels holding several thousand feet, but where the upper part of the line was inaccessible to wagons, the rope, like the rest of the machinery, had to be packed so that it could be loaded on mules. Each animal carried about 250 pounds (115 kg) – including the piece of slack rope fifteen or twenty feet long connecting its load to the next one in the rear. This piece was usually held up by a walking person so that it would not drag on the ground. Accidents happened, of course. A two mile long ropeway in Mexico for conveying wood to a mill had a fall of 3,575 feet. The constructor notes:

The transport of this rope was, owing to the rough nature of the country to be traversed, a matter of very serious difficulty. It was accomplished by dividing the rope into ten lengths, each length made up into seven coils, with an intermediate length of ten feet, and each of the coils was loaded upon the back of a mule, the entire train being composed of 70 mules and three men being provided to each seven mules, or thirty men altogether.

During the conveyance of the section of rope to the upper terminal an accident occurred which was productive of very considerable delay, and demonstrated the difficulties attendant upon the operation. The head mule, at a point where a rise immediately followed a steep descent, started to take the rise with a rush until checked by the rope, which threw him backwards over the bank, he taking two other mules with him, and had not the last of these caught on a tree, the rest of the train would have followed.

The Many Advantages of Ropeways

Why did aerial ropeways become so successful at the turn of the twentieth century? The main reason was that they were considerably cheaper than their alternatives, be it transport by horses and carts or transport by railroad. The ropeway was economical in operation and required only a minimal capital outlay. The investment that would be entailed in a hilly country by the necessity of making tunnels, cuttings and embarkments for a line or railway was avoided. A cableway could be constructed and worked on hilly ground at a cost not greatly exceeding that which would be called for on a level country. Rivers and ravines could be crossed without the aid of bridges. Gradients quite impractical to ordinary railroads could be worked with ease.

One calculation showed that a ropeway only one mile (1,630 metres) long with a difference in altitude of 0.4 miles (645 meters), would require a railway of fifteen miles (24 km) to reach the same point. Ropeways were also generally half as expensive to operate when compared to cartage by mules, horses, and oxen. Furthermore, an aerial tramway could be up and running in no time. Some lines could be easily moved from one place to another with comparative ease. An installation of one mile length at a beetroot farm in Holland, with a daily capacity of fifty tons, could be taken down and put up again in a fresh place in one day, by the aid of twenty men, provided the distance to cart the component materials did not exceed five miles.

Ropeways continued to work during weather conditions that would bring surface hauling to a standstill (like floods or heavy snow, especially interesting in mountain areas) and they could be operated at night without hazards. Wear and tear were relatively low. Ropeways did not occupy any material quantity of ground, and the intervening land between posts could be left for cultivation or other use. Terminals could be arranged so that the material transported could be delivered at the exact spot where it was needed, saving all the expense of rehandling. One disadvantage that ropeways had was that they were more vulnerable to high winds and electrical storms than other transportation options.

Cargo Tramways Today: Renewed Interest

The advantages of aerial cargo ropeways are so numerous that it is no surprise that they are – slowly – being rediscovered. Worries about global warming, peak oil and environmental degradation have made the technology even more appealling. This does not only concern energy use: contrary to a road or a railroad track, a cargo ropeway can be built straight through nature without harming animal and plant life (or, potentially, straight through a city without harming human life). Traffic congestion also plays into the hands of cableways, because the service is entirely free from interference with surface traffic.

Practical Action has been designing cargo ropeways in Latin America for some time now as an appropriate tech solution. In this case, aerial ropeways are mostly a substitution for pack animals, as they were one century ago in Europe. In 2007, another non-governmental organization built a gravity powered cargo ropeway in India that serves 2,000 families. It costs just $ 14,000 and transports agricultural produce downhill while taking manure to fertilize the fields uphill.

Some companies have started offering commercial cargo ropeways again. One of these is Femecol, a Colombian enterprise that offers relatively small-scale solutions. But the big guys are moving, too. French company Poma, one of the largest manufacturers of chair lifts, gondola lifts, funiculars and people movers, has constructed industrial applications of ropeways in France, Brazil, Iran and Peru. In these and in the following applications, aerial ropeways are mostly a substitute for cargo transportation by trucks. The first modern Poma cargo tramway was built in 1990 in Grenoble, France. It is operated for a cement factory and crosses a river and a motorway. The line is 1.8 km long, climbs 121 metres and can handle 324 tonnes per hour – a capacity that is considerably higher than that of older systems (though the line is rather short). Each of the 56 vehicles can hold 900 kg and travel at a maximum speed of 18 km/h.

More recently, a similar cargo ropeway was built in La Oroya, Peru for the lead, zinc and copper mining company Doe Run. It has a similar length to the line in France but climbs 1.65 km. It is much slower (5.4 km/h) and it has a lower capacity (70 tonnes per hour – similar to the capacity of the larger systems built in the first decades of the twentieth century). It should be said that the ropeway – which replaced a much older system with a smaller capacity – seems to be the only sustainable element of the mining company, because Doe Run is in hot water with local environmentalists.

Innovation: RopeCon System

The main competitor to Poma, the Austrian/Swiss conglomerate Doppelmayr Garaventa Group, takes cargo tramways even more seriously. On their website, they offer cargo ropeways with lengths of up to ten km, transport capacities of up to 1,500 tonnes per hour and individual loads of forty tonnes. A temporary, two kilometre long system is being built to help in the construction of a pumped storage hydropower plant in Switzerland. But the company also designed a new concept that further improves upon the cargo ropeway: RopeCon. Mining Weekly describes it as “a bulk material and unit load handling conveyor, which combines the benefits of well-proven ropeway technology with those of a conventional conveyor belt”.

Some of the advantages over the traditional ropeway are a higher load capacity, better wind resistance, and the need for fewer towers (which makes the lines even easier to integrate into existing terrain). The overhead conveyor system consists of a belt with corrugated side walls and integrated sets of wheels that run on fixed anchored track ropes, guided over tower structures. Individual sections can be built up to a length of twenty kilometres, with a maximum transport capacity of 10,000 tonnes per hour. To date, about six lines have been built.

The most spectacular system, which has been tested in hurricane winds of 249 km/h, was built in 2007 for a Jamalco/Alcoa bauxite mine on Mt Olyphant in Jamaica. It is 3.4 kilometres long and has a vertical descent of 470 metres. The installation conveys some 1,200 tonnes of bauxite per hour from the mine to the processing plant, generating about 1,300 kWh of braking energy per day, which is fed back into the power network. The transport network thus doubles as a renewable energy plant.

Another remarkable cargo installation is the RopeCon for fiber manufacturer Lenzing, which is used for the transport of wood chips from the storage area to the processing plant. The 665 metre long automatic transport system crosses existing plants and conveyor systems, a river and several roads with minimum tower structures. The ropeway conveys 350 tonnes per hour, and although the system does not generate energy because it is built on flat terrain, the engine output is only 53 kW – similar to that of a small car. The line was designed to guarantee 100 percent availability at wind speeds of up to 130 km/h.

Since May 2008, a system on the island of Simberi in Papua New Guinea transports gold ore over a distance of 2.7 km while using only three support towers over the entire length. The ore is transported from the mine in the interior of the country through the tropical rain forest and fissured terrain to the smelting facility at the harbour. The vertical rise is 237 metres. Transportation capacity is 450 tonnes per hour and the system generates 221 kWh of energy per day through braking power, which is utilized in the gold refinery.

A temporary RopeCon installation was set up for the construction of a tunnel in Austria, where it was used for the transport of rock excavation material. Conveying capacity was 600 tonnes per hour, while engine output was very modest at 30 kW. The line was 270 metres long, with a vertical rise of 23 metres. It eliminated 115,000 truck journeys.

The Future of Ropeways

It would be perfectly possible to construct similar lines all over the place and get most cargo traffic off the road – not only when it comes to gold or bauxite mines. A cargo tramway could be built from a train station or parking lot outside the city to a shopping mall, or along the motorway between two towns or cities. We could send produce from agricultural fields and goods from factories straight into shopping districts or into a moored ship, without ever touching the ground. There would be no delays due to gridlocks or traffic accidents. Noise and vibration would be minimal. The low energy requirements could easily be met by renewable, stationary energy sources.

We could even build a fully-fledged local, regional or even national or international transportation network of cableways using switch stations that would be cheaper in capital and operational costs than any other alternative. Of course, yesterday’s ropeways are not suited to handle today’s freight loads. For example, today, 400 trucks of 30 tonnes each drive up and down daily between Granada and the harbour in Motril, Spain. That is a total load of 12,000 tonnes, while the local ropeway that was in operation from 1925 to 1950 had a capacity of only 210 tonnes per day (for 10 working hours).

However, as noted, Doppelmayr now offers cargo tramways with capacities of up to 1,500 tonnes per hour, which would be more than enough to get all trucks off the road again. RopeCon systems offer even higher capacities. On the other hand, lowering demand for cargo transport would defenitely make ropeway technology a more realistic option, just as lowering energy demand would surely help the greening of the energy infrastructure. Ropeways won’t work everywhere, and they are most advantageous in mountainous or moderately level regions. This is not only because a vertical rise can turn the ropeway into a power generator instead of a power consumer, but also because the alternatives (rail, road) are more expensive and complicated to build than on level terrain.

Nevertheless, even on flat ground a cargo ropeway could be a more sustainable option than most other alternatives. The only motorized transport option that seems to be able to compete with the ropeway in terms of both capacity, efficiency and cost is canal transport – even more so if trolleyboats were used. Canal transport is best suited for level regions and thus perfectly complementary with cableways. And what about those trucks? They are so twentieth century. ←

Ropeway in Gdansk, built by Wybe Adam, 1644.

Ancient ropeway.

1411 drawing of a ropeway.

1724 drawing of a ropeway. Leupold la macchina di Danzica.

Aerial ropeway for transport of produce in agriculture.

Aerial ropeway in a harbour.

Aerial ropeway in a harbour.

For every material carried by a tramway, there was a specially designed carrier receptacle.

Aerial ropeway transporting lumber.

Argentinian ropeway (1906-1927). Image: Patricio Lorente. (CC BY-SA, 3.0)

A ropeway station.

Packing traction rope over a mountain trail.

A mules train transports a wire rope up the mountain.

A Ropecon system in Jamaica. Image: Doppelmayer.

A Ropecon system in Jamaica. Image: Doppelmayer.

References

The Information Center for Ropeway Studies, “About ropeways”.

Wood, Jeff (Ed.; Reconnecting America) (2007). “Hercules Aerial Tram Mobility Study
& Report”. (Investigates a wider application
of passenger ropeways, but also has
interesting information on cargo
ropeways.)

“The wire rope and its applications”, (1896).

“Ropeways”, The Elevator Museum (website, 2012), http://www.theelevatormuseum.org.

“Aerial or rope-ways: their construction and management” (1911).

Carrington, W.T.H. (1899). “Transport by Aerial Ropeways”, The Engineering Times.

“Die Drahtseilbahnen” (1914).

“Chemins de fer funiculaires - transports aériens” (1894).

Spilsbury, Edmund G. (1890). Wire rope tramways with special reference to the Bleichert patent system.

Wire rope transportation in all its branches, Trenton, N.J.: Trenton Iron Co. (1892).

Hewitt, William (1909). The Bleichert system of aerial tramways, Trenton, N.J.: Trenton Iron Co.

Hewitt, William (1898). Across the Chilkoot pass by wire cable, n.p.

Poyo, Francisco Calvo.”El cable Dúrcal-Motril (Granada)”, Universidad de Granada.

California Wire Works (1902). The Hallidie endless wire ropeway.

“Un po’ di storia degli impianti a fune”, Associazione Nazionale Italiana Tecnici Impianti Funiviari.

Santa, Eduardo (2003).“Palomo Aguirre: El bandido que asaltaba el cable más largo del mundo”, Credencial Historia, No. 158.

Temple, Robert K. G, & Joseph Needham (1986). The Genius of China: 3,000 Years of Science, Discovery, and Invention. New York, N.Y: Simon and Schuster, 1986.

Needham, Joseph (1986). Science and technology in China Volume IV: 3. Cambridge; New York: Cambridge University Press.

Hand Powered Drilling Tools and Machines

During the last quarter of the 19th century, a radically improved generation of tools appeared.

Hand-powered devices have been used for millennia. However, during the last quarter of the 19th century, hand tools took advantage of modern mass production machinery and processes (like interchangeable parts) and an increased availability in superior material (metal instead of wood).

One of the outcomes included an array of new drilling machines. These human-powered tools were not only a vast improvement over those that came before them, they also had many advantages in comparison to the power drills that we use today.

Drilling Holes

For most of human history, drilling a hole into whatever chosen material required an extensive amount of time and effort. The first crude drilling tool was the awl, a sharp stone, flint, copper or bone point that could be attached to a piece of wood. The awl was pressed against an object and then rotated by hand, much like a present-day screwdriver. An alternative primitive method was the hand drill or shaft drill, where a stick was rotated between the palms. Abrasives such as sand could be used simultaneously to make this drilling method more effective.

These were extremely labour-intensive tasks, especially when the material that had to be drilled was hardy, like stone. In his study of ancient stone-working technology, Denys Stocks came to the conclusion that even with a bronze drill bit it took up to five hours to drill a tiny hole one centimetre deep in a hard stone like quartz. Drilling holes into hard stone was commonplace in ancient times, for example in construction work and the making of necklaces and bracelets, so it is not surprising that our forebears were investigating more efficient drilling methods with fervour.

Strap Drills, Bow Drills and Pump Drills

The first step toward mechanisation was the strap drill (also known as cord drill or thong drill), which offered an increased rotation speed of the drill bit. The tool consisted of a drill bit attached to a longer wooden shaft, which was rotated by wrapping a cord or leather strap once around it and holding the ends with one’s hands; by pulling in one direction and then the other, the shaft spun and drilled into the material. The top of the shaft rotated freely in a mouthpiece which was held between the user’s teeth to exert more downward pressure. The tool was also used to make fire, which is the reason why it is also known as a fire drill.

The strap drill was widely used, but was eventually superseded by the bow drill, which appeared at least 6,000 years ago in Egypt. Based on the cord drill, the difference was that the cord or strap, again wrapped once around the shaft, was tied to a bow. Holding the drill vertically and the bow horizontally, the user then moved the bow backward and forward – much like a cellist – to revolve the shaft.

The bow drill possessed two advantages over the strap drill: the shaft could be rotated at a higher speed, and as only one hand was needed to handle the bow, downward pressure could be exerted with the other hand instead of the mouth. Smaller bow drills were also used for dental care. The tool could be made from a few pieces of wood, a piece of string and a drill bit. A later improvement to the bow drill was the pump drill, which appeared in Roman times. It is similarly operated, except it functions by means of a downward instead of sideward movement. Sandor Nagyszalancy explains how it works in his book Tools Rare and Ingenious:

Pump drills get their name from the way they’re used. Pumping the crossbar up and down causes a string to wind and unwind at the shaft, thus spinning a pointed bit that’s fastened to the end of the shaft back and forth. The thick, rounded section just above the bit serves as a small flywheel to keep the spinning motion going.

Once more, the pump drill offered superior rotating speeds and more downward pressure. All these ancient drills were used in conjunction with a sharp drill point or with the help of abrasives (especially when drilling through stone). Pump and bow drills are among the most successful tools ever made. Bow drills were still used in the western world at the end of the 19th century by carpenters for drilling small or delicate holes, whilst small pump drills are still sold today as a tool for jewellers.

Bow and Thong Drills Operated by Several People

The Chinese were especially keen on the above drilling tools. They relied on bow, pump and thong drills up until the beginning of the twentieth century and never developed any of the drilling tools that will be discussed further below. Rudolf Hommel photographed some of the Chinese drilling devices in his book China at work. Chinese shipbuilders employed a larger version of the thong drill which was operated by two to three people. It was used for drilling the preliminary holes for the iron spikes which they utilized in ship construction. Henry Chapman Mercer describes the tool in his 1929 book Ancient Carpenters’ Tools:

To work the apparatus, the thong is twisted around the spindle, whereupon one man holds down the pivot handle, thereby pressing down the drill bit into the wood, while two other man, each grasping the thong by one of its terminal handles, or one man holding a thong-handle in each hand and pulling the thong to and fro, cause the drill to twirl back and forth, as with the common bow drill.

According to some historians, the Egyptians also made use of large bow drills operated by several people to make large holes (and to hollow out spaces) in their pyramids. Bronze hollow tubes of about 11 centimetres in diameter in conjunction with abrasives would have been used as a drill bit (tube drills or core drills), after which the remaining core is then carefully removed. Even larger holes could have been made by performing several drilling operations right next to each other, in a circular form. The core drill allows for larger holes without sacrificing drilling speed, because much less material has to be reduced to powder.

Denys Stocks conducted real-life experiments to see if this method could work, and succeeded. The results indicate that two drillers were required to push and pull a large bow, while a third person balanced a stone drill-cap on top of the shaft to exert downward pressure. Stocks achieved a drilling speed of two centimetres per hour in granite stone, and thinks the ancient Egyptians could have reached speeds of twelve cm per hour. Whether or not the ancient Egyptians applied this technique remains open to debate, though. Archaeological remains of these tools have never been found, and unlike smaller drilling operations (common bow drills, stone drills to hollow out granite vases) these large-scale operations were only vaguely alluded to in wall paintings.

Augers, Gimlets and Reamers

Another very important invention from Roman times was the T-shaped auger (and the much smaller gimlet), basically a long drill bit with a pair of wooden handles for rotating it. The tool looks like an oversized corkscrew. Augers were used to drill large and/or deep holes in wood, for which the bow or pump drill was not very useful. They were applied by shipbuilders, bridgebuilders, millwrights, wheelwrights and the like. In the Middle Ages augers were sometimes equipped with a breastplate on top for more drilling pressure – the user could rest the entire weight of his body on the pad. However, operating them was a tedious task. The Roman writer Vitruvius noted that the difficulty of the boring increased exponentially with the diameter of the hole. Apart from drilling holes, an auger was also used for “reaming” – enlarging an already existing hole.

The drilling action of the auger is based on the principle of leverage: the longer the handle, the greater the potential of applied force. Some augers and reamers were huge and had to be operated by several people. One example is the wheelwrights’ reamer, which was used to core the hub of a wheel in order to receive a metal bearing. This was again no easy task, because if the hole was not perfectly straight, the wheel would hobble along on the axle. Augers and reamers were essential tools until the end of the 19th century. Eric Sloane describes the use of the tool in his 1964 book A Museum of Early American Tools:

Oddly enough, the experts have not decided just how these reamers were used. But I rigged up a wagon wheel on a wheelwright’s bench, then put a hooked reamer through the hub, which I had weighted with 75 pounds. With two men turning a very long detachable handle it worked nicely. With an ordinary reamer, a man exerts about half its weight downward; this can be bettered with a 75 pound weight plus the 25 pound weight of the tool itself.

Pipe and Pump Augers

Another spectacular example was the pipe auger (and pipe reamer). These tools were used to bore water pipes from tree trunks. This kind of wooden water pipes was quite common in towns and smaller cities from the 15th to the 17th century, notes Maurice Daumas in Histoire générale des techniques. Stephen Shepherd, author of the Full Chisel Blog, explains how the pipe auger is operated:

This type of bit will follow the center of the tree (they selected good straight trunks of the appropriate diameter) so the hole will be centered. What is unusual about this arrangement is the very long shank and the interchangeable bits and reamers. Some pipe auger handles were segmented and lengths could be added as needed. The shanks were slightly longer than the logs being made into water pipes. Twenty feet (6 metres) is not an uncommon length.

There is a permanent set-up to do the work. Saw bucks or stantions to hold the log and smaller ones to hold the shank of the bit in the proper location. After the pilot hole is bored, the bit is changed out to a reamer to enlarge the hole. In order to facilitate the reaming, a rope is run through the hole and fixed to the hook on the end of the reamer. Now the work gets easy for the fellow twisting the handle as he no longer needs to push the auger, the fellow on the other end pulls the rope (also one with weights), pulling the reamer through the pilot hole enlarging the opening, as the handle is twisted.

This took quite some time. In his 1751 Encyclopédie, Diderot writes that one man could bore a 5 cm diameter hole through 11.6 metres of pipe per day in alder or elm, but only 1.95 metres per day in oak. A similar method was used for boring the barrels of muskets and cannons, and for making wooden water pumps to get water up from wells or chisels.

Continuous Versus Reciprocating Drills

The arrival of the auger did not nullify the bow and pump drills. Each had their advantages and drawbacks because they work in totally different ways. Firstly, with a bow or pump drill, downward pressure is applied by one hand, while with an auger it is applied by two hands. Second, the auger turns slowly in one direction, while the pump and bow drill work by quick reciprocating revolutions in both directions. The auger pares the wood into shavings as it goes down; the pump or bow drill pulverizes the wood into sawdust.

The result is that the auger is much better suited to drill large holes, but not useful to make holes in materials other than wood. On the other hand, pump and bow drills will only drill comparatively small holes (with the possible exception of the large Egyptian tools), but can be used for drilling holes in all kinds of materials that need to be pulverized instead of pared: stone, marble or metal, for example.

Medieval Breakthrough: the Hand Brace

While augers remained essential tools for large diameter holes until the end of the 1800s, the Middle Ages brought an important drilling innovation when it came to somewhat smaller holes: the hand brace or bitstock. It introduced – for the first time in history – a drilling motion. Both bow drills and augers worked by means of intermittent rotations, and during the short pause in between turns the drill bit had the tendency to get stuck. The U-shaped body of the brace solved this problem. The user turned the handle continuously while exerting downward pressure with the hand or the chest on the pad (some later braces, the cage-head braces, had a larger breastplate). Braces came in many different sizes, with lengths varying from ten centimetres or less to tools almost half a metre long.

The earliest representation of the hand brace dates from 1425, when it appears on a painting by the Flemish artist Robert Campin. The oldest surviving brace was recovered from an English ship that sank in 1545. Hand braces have remained in use ever since, although they can be difficult to find today. From the 15th to the beginning of the 19th century, braces improved only moderately. Early wooden braces were made with bits permanently attached, while later models had crude mechanisms for interchangeable bits. The shape of the tool hardly changed, but there was an evolution in the materials used.

Most medieval hand braces were made almost entirely out of wood (sometimes even a naturally curved limb of a tree) with some minor iron reinforcements, and – of course – an iron drill bit. Later models were heavily reinforced with metal plates. Some braces were very crude, while others may be considered works of art. The early 19th century Ultimatum braces made by William Marples, crafted from japanned ivory or exotic wood (ebony, rosewood) and decorated with engraved and polished brass sidings, were famous for their aesthetic appeal.

Modern Hand Powered Drilling Tools

The next revolution in hand powered drilling tools only occured at the end of the 19th century, with the arrival of much improved hand braces and a whole new class of drilling tools: geared drills and boring machines, which took over the heavy duties from augers. They were much more powerful and versatile than their predecessors, but unfortunately their success did not last long. Half a century later they were almost completely superseded by electric power drills. As a result, many people are not even aware of the existence of these remarkable tools.

In the overview of modern hand powered drilling tools that follows, I will focus almost exclusively on the products of one enterprise: the Millers Falls Company from New York. Although there were a few important competitors, notably Goodell Pratt and North Brothers, Millers Falls dominated the market in the US and their tools are generally regarded as the best. Moreover, since the US became the forerunner of early mass production techniques, these tools became an example for most European manufacturers too.

The improvement of drilling devices was mainly the consequence of the arrival of cheap steel and the invention of interchangeable parts. Randy Roeder, author of a splendid website dedicated to Millers Falls Tools (called Old Tool Heaven), summarizes the changes in two paragraphs, using the hand brace as an example:

The braces being offered by American companies at this time were among the finest hand-powered boring devices ever mass produced. The braces of the 1930s would have been a dream come true for a woodworker a century earlier. In the early nineteenth century, most braces were made of wood and prone to breakage if too much torque was applied to them. The forged iron braces sometimes made by blacksmiths were better in this regard, but both types were plagued with mechanisms inadequate to hold a bit securely and incapable adjustment for variations in the size or shape of a shank.

One hundred years later, a brace with an adjustable Barber chuck (patented in 1859), mounted on a quality steel frame and fitted with a rotating sweep handle and ball bearing head was considered bottom of the line. Better models came equipped with a ratchet mechanism allowing the user to bore a hole without making a full rotation of the sweep. Some of the best braces were manufactured with all or part of the ratchet mechanism enclosed, or boxed. Premium models came equipped with chucks which allowed for bits with a variety of shanks to be used. Fit and finish, of course, played a role in determining the eventual cost of the tool.

Hand and Breast Drills

Apart from the improvement of the centuries-old hand brace, a whole new range of drilling tools appeared – most notably, so-called geared drills. The earliest picture of a geared drill appears in 1816 and the first geared drill patent is from 1838. It is most likely that they originated in France, perhaps as late as the end of the 1700s. Geared drills finally offered metal workers an alternative to the 6,000 year old bow drill and the 2,000 year old pump drill. WK Fine Tools, a website dedicated to late 19th century drilling tools, explains:

A geared drill transfers its power from a vertical hand cranked main gear to a horizontal pin gear spinning on a shaft connected to a bit holding device. Depending on the size ratio of main gear to pinion a greater number of revolutions could be achieved from one turn of the crank.

Geared drills (also named eggbeater drills) were initially made for drilling in metal, for which higher rotation speeds are a necessity. However, they were also used for drilling into soft wood, in which case the mechanical advantage simply led to easier drilling. Like hand braces, geared drills worked by continuous motion, but they offered the additional benefit of making the drill turn faster than the rate at which the crank is turned. Many models also offered the possibility of changing the bit rotation speed. Geared drills came in two varieties: hand drills and breast drills. Millers Falls Company started mass producing them in 1878 and remained market leader ever since. Randy Roeder explains the differences between the two types:

Hand drills are generally fifteen inches or less in length, are best suited for drilling holes in wood and light metals, and are most effective when used by a worker whose body is positioned above a work piece. They work best when operated at high speed and are especially useful for accurately drilling small-sized holes without damaging delicate drill points.

Breast drills typically exceed fifteen inches and are topped by a concave plate that provides a surface which the user can lean against when boring a hole. Sometimes referred to as chest drills, belly drills or knee drills, these tools were indispensable in the construction industry, in blacksmith shops, in factories and in shops where rail cars were fabricated. Ruggedly built, the drills are useful for boring holes in iron, steel and extremely tough wood. Designed with the expectation that a worker would be putting a fair amount of body weight into a task, the breast drills are especially effective when used in a standing position, alongside the work piece.

Breast mills, even though they were human powered, could be very powerful tools. An example is the Millers Falls No. 13 breast mill, which was introduced in the mid-1880s. It had a driver that was six inches (15 cm) in diameter, which provided for a gear ratio of 4.5 to 1. This means that the drill bit spun 4.5 times faster than the user’s hand. Later models had even higher gear ratios. The No. 666, which was introduced in 1937, had a mechanical advantage of more than 7 to 1. The breastplate replacing the knob did more than merely allowing the user to push his chest into the drill, notes Stephen Shepherd:

It also freed his hands to turn the crank and hold an auxiliary handle on the pivot and opposite the crown wheel. The length of the arm to the turning knob varies from a knob mounted to the rim of the wheel, to a bar that extends beyond the wheel adding to the mechanical advantage.

More than 200 Different Models

Hand braces and geared drills came in a surprisingly large variety. In 1915, the inventory of Millers Falls included 28 hand drills, 40 breast drills and 135 variations on the hand brace – especially the latter figure is remarkable considering the tool’s simplicity. One example is the Whimble Brace, of which the catalogue description reads as follows: “Ship builders, bridge builders and others whose work requires an unusually powerful sweep will find this brace a strong, sturdy tool, capable of standing the rough use to which it is necessarily put”. Or take the Corner Brace, which was “the only practical tool for boring in corners and close to walls, and is indispensable to carpenters, bellhangers and plumbers”.

Both braces and hand and breast drills could be mounted in special frames. The result was a hand powered drill press, bench drill, post drill or beam drill, which further improved the performance of the tools. An example is the mounted breast drill, which was presented in 1883 (called the Universal Hand Drill Press). The magazine Carpentry and Building devoted an article to it:

A steel frame is provided, in which the No. 10 breast drill may be used quite advantageously. The drill is held true by the frame, and the work is held firmly in place by the clamp shown in the engraving. The lever-feed provided by this arrangement may be operated by hand, or a weight may be employed, as may be preferred. The advantage of an attachment of this kind for use in connection with a breast drill is obvious.

Most of the work done by a tool of this character can be better performed with the drill mounted in the frame. When the breast-drill is used in the ordinary manner it very frequently requires heavy pressure, which is quite fatiguing to the workman. In the arrangement shown there is a leverage of five to one, which makes the feeding an easy matter. When work is required that cannot be done in the frame, the tool can be taken out in a very small space of time, and used in the ordinary way.

Many different frames were available, and the same principle could also be applied to the hand brace. Angular and ratchet drilling machines could be attached to broken machines and swung around so as to drill at a variety of angles. Apart from the advantages listed above, this arrangement also gave the operator the advantage of keeping one hand free. A variant of such a stationary hand powered tool was the wood boring machine. This two-handed drill was the most powerful model the Millers Falls Company made, and was introduced in the 1860s. An adjustable model drilled at any angle, while the wooden base that holds the superstructure is a seat for the operator to sit on. Stephen Shepherd used the machine and was impressed:

The two hand cranks and gear mechanism makes this an aggressive drill, even with big twist bits. It easily bores big holes in timber. At the proper depth, the rack gear is moved to engage a gear and continuous turning of the hand crank pulls the bit out of the hole with the greatest of ease.

A completely different hand powered drilling machine (not manufactured by Miller Falls) was especially designed for piercing through tough rocks. The Ingersoll Hand Power Drill is pictured and described in the 1892 encyclopedia Modern Mechanism:

The spring is compressed by the lifting of the cross-head, and its recoil on release produces the blow, which is delivered dead on the stone without shock to the men. The spring ordinarily supplied for a drill to be worked by 2 men is compressed to 200 lbs, and produces with the momentum of the working rod and drill a blow of about 300 lbs.

Continued Availability

The continued availability of some hand powered drilling tools is at least as remarkable as their diversity. For instance, the Millers Falls No. 2 hand drill, one of the company’s most popular eggbeater drills, was introduced as early as 1878 and could still be found (largely unchanged) in their 1981 catalogue – over 100 years after its introduction. The No. 2 hand drill even survived the introduction of the so-called Buck Rogers hand drill, its more radically designed modern looking cousin with enclosed gears, which appeared in the late 1940s and was discontinued by 1960. The No. 2 is the most spectacular example when it comes to availability, but most other conventional models remained available for many decades, too.

Nevertheless, the heydays of modern hand powered drilling tools were over fast, even before the 1920s began. While Millers Falls had 135 different models of hand braces in its 1915 catalogue, the number of braces in the catalogue had shrunk to 35 by 1938 and to 13 in 1949. Randy Roeder explains what happened:

The growing preference for electric boring tools was making itself felt in the workplace, and it is plain that the market could no longer sustain a huge line of braces, many of them differing only slightly from another. Oddly, the company continued to market breast drills into the 1980s. Although the drills were already an anachronism, competitors were so few that it had the market pretty much to itself.

The 1981 Millers Falls catalogue features only three braces, one hand drill and one breast drill. Today, new hand braces and breast mills can still be bought, but they are rare.

Pinnacle of Drilling Machinery

The interesting thing is that the drilling tools that appeared in the late 19th century were not only a vast improvement over earlier tools; they also have many advantages over their present-day successors, the power drills. Of course, as most modern products, power drills offer the advantage of convenience: merely pushing a button will do the job. But that luxury comes at a steep price. Obviously, any interruption in the electricity supply will render a power drill utterly useless. The simple operation of drilling a hole would then be impossible, which is quite remarkable since less than 100 years ago no electricity was needed to perform the job almost as quickly as today.

Power drills are also dependent on fossil fuels for the manufacture of their materials (mostly plastics) and their electronic components, as well as for the mining of the resources to make these (rare earth metals included). Naturally, manually powered drills require energy for their manufacture, too. They are made almost entirely from iron and steel with nickel plating. But there is a crucial difference to consider here; even if we assume that the embodied energy of a hand drill is similar to that of a power drill, it has a much longer service life.

Hand tools that were sold in the 1870s and saved from the junkyard by antiquarians or nostalgic craftsmen can still perform their tasks without any problem today, even when they were unused for decades – a bit of cleaning (using gasoline) was all that it needed. These tools were made to last. Furthermore, the continued availability of the same models for many decades guaranteed that spare parts remained available. A hand powered drill hardly requires any maintenance to be kept in good shape. Oiling the tool from time to time suffices. After years of intensive use, they might need new wooden handles, but that’s all. An electric drill requires much more attention, because it consists of much more parts – and more delicate parts, too.

The electric tool must be opened periodically for cleaning and oiling to keep it running smoothly. The brushes should be inspected and replaced from time to time. Wiring and circuits should be checked. In the case of a corded drill, the cord is prone to damage. The machine has to be kept away from dust, rain and high temperatures. The possibility of something breaking down is much higher than in the case of a hand powered tool. Since it is mostly cheaper and easier to replace a high-tech product than to repair it, this means that power drills won’t last 100 years or more. They will have to be manufactured again and again. Even if it is maintained good and used for a long time, a cordless power drill will regularly need new batteries, again raising energy and material consumption, as well as dependency on a delivery infrastructure that might not always be there.

Silent, Safe, Flexible, Forgiving

Even when disregarding energy and environmental issues, hand powered drills offer some real, practical advantages. They are rather silent, while power drills can produce up to 130 decibels of noise. Their independence from electricity and batteries also guarantees that you can use them anywhere you want for as long as you want, unhampered by cords that are always too short and batteries that never last long enough.

Manually powered drills are also much safer than power drills, and because of their lower drilling speeds and more direct control, corrections are much easier to make while drilling a hole. Of course, the lower rotation speed can also be seen as the (only) drawback of a hand powered drill. They can do all the jobs that we now use power tools for, but for large and/or deep holes in hard materials this will cost more time and some exercise – and that’s enough for us to laugh at them.

Low-tech or High-tech?

We always compare simpler solutions like hand powered drills to modern, unsustainable machinery, and never to the tools that came before them. Hand powered drilling tools are indeed low-tech if you compare them to power drills. However, they are definitely high-tech when you compare them to bow drills, augers and crude wooden hand braces. The hand drills that we now disregard are products of the industrial revolution, and they should not be taken for granted. Efficient hand powered drills require good steel, mass production factories, and oil to keep their gears in shape.

One last thing. It is important to note that this article only discusses the history of hand powered drilling tools and machines. From the late Middle Ages onwards, large scale drilling and boring was also performed by animal power, water power and wind power, requiring no human effort at all. Large-scale drilling operations became more important at the end of the 19th century, which led to a whole new range of machines equipped with steam engines and electric motors. No attempts to improve the existing water and wind powered boring machines with interchangeable parts and better materials were made. ←

A carpenter using a hand brace, 1942. Alfred T. Palmer. Library of Congress.

1872 patent premium model lever-type ratchet. Image: Randy Roeder, oldtoolheaven.com.

A rare combination of hand brace and geared drill, 1880. Image: Randy Roeder, oldtoolheaven.com.

A breast drill. Image: Randy Roeder, oldtoolheaven.com.

The whimble brace, one of 135 variations on the hand brace.

The corner brace, one of 135 variations on the hand brace.

Millers Falls Mounted Breast Drill, 1883.

The strap drill.

A bow drill in use. Rudolf P. Hommel, China at work, 1937.

A thong drill. Rudolf P. Hommel, China at work, 1937.

English hand braces. Hans Brunner Tools. http://www.hansbrunnertools.com

Boring water pipes with a pipe auger. From De Re Metallica, Agricola, 1556.

References

19th century drilling tools:

Roeder, Randy. Old Tool Heaven: Milles Fall Home Page (website, s.d.). http://oldtoolheaven.com/index.html.

General information as well as a description and picture of every Millers Falls drill tool ever sold including one-hand operated push drills which I have ignored here.

WK Fine Tools (website, s.d.). : http://www.finetools.com/.

In-depth information of Millers Falls drills and other drilling tools. There is a complete anatomy of the N0.2 hand drill to be found, as well as a broad overview of UK and US boring tools and their makers (including patent drawings of many tools).

Langford, George. “Type study of the Millers
Falls No. 2 Eggbeater Drill”, Georges Basement (website, 2004). http://www.georgesbasement.com/mfno2typestudy/mfno2types.html.

Shepherd, Steven. Full Chisel Blog (website, s.d.). Accessible through https://web.archive.org/web/20080314001339/http://www.fullchisel.com/blog/.

Millers Falls Company catalogue (1904). http://www.wktools.com/index.asp

Millers Falls Catalogues 1925 (or 1939), 1949 and 1981 on Rose Antique Tools (website, 2001). http://www.roseantiquetools.com/id82.html.

Zitur, Chuck. Boring Tools (website, s.d.). http://chuckzitur.galootcentral.com/boring.htm.

1891 catalogue of breast drills and braces manufactured by H.S. Bartholomew. http://www.wktools.com/index.asp

1923 Goodell-Pratt Company catalogue. http://www.wktools.com/index.asp

1926 Yankee tools catalogue. http://www.wktools.com/index.asp

Zitur, Chuck. Metabo Tool Brochure 1930s (website, s.d.). http://chuckzitur.galootcentral.com/metabo.htm.

The American Patented Brace Database. http://www.mwtca.org/the-gristmill/sample-articles/81-the-american-patented-brace-database.html.

Knight, Edward H. (1881). American Mechanical Dictionary, http://www.princetonimaging.com/library/mechanical-dictionary/.

Benjamin, Park (1892). Modern mechanism; exhibiting the latest progress in machines, motors, and the transmission of power. New York: D. Appleton.

Ancient & medieval tools,
general history:

Sloane, Eric (1964). A Museum of Early American Tools.

Nagyszalancy, Sandor (2004). Tools Rare and Ingenious: celebrating the world’s most amazing tools. Newtown, CT: Taunton Press.

Sandor Nagyszalancy, Sandor (2000). Art of Fine Tools. Newtown, CT: Taunton Press.

Mercer, Henry Chapman (1929). Ancient Carpenters’ Tools illustrated and explained ... Doylestown, PA: Bucks County Historical Society.

Goodman, William (1964). The history of woodworking tools. London: Bell & Hyman.

Rybczynski, Witold (2001). One Good Turn: A Natural History of the Screwdriver and the Screw. New York: Scribner.

Hommel, Rudolf P., & Volunteers in Asia, inc. (1937). China at work: An illustrated record of the primitive industries of China’s masses, whose life is toil, and thus an account of Chinese civilization. Cambridge, Mass: M.I.T. Press.

McGuire, J.D. (1894). A study of the primitive methods of drilling. Bulletin of the US National Museum. Washington: U.S. National Museum.

Drilling and boring tools, Encyclopedia Britannica, 1995 edition

Stocks, Denys (2003). Experiments in Egyptian Archaeology: Stoneworking Technology in Ancient Egypt, Londen: Routledge.

Dumas, Maurice (1964). Histoire générale des techniques - tome 2: Les premières étapes du machinisme Xve-XVIIIe siècle, Paris: Quadrige, Presses Universitaires de France.

Stocks, Denys (1999). “Stone sarcophagus manufacture in ancient Egypt”, Antiquity, 73 (282), 918-922.

de Garis Davies, Nina & Norman (1943). The Theban tomb series. http://ancientegyptdigitalibrary.blogspot.com/2016/04/davies-nina-and-norman-de-garis.html)

Hitoshi Endo, Izumi Takamiya, and Renée Friedman (2009) Field Note 3: Beads and bead making at Hierakonpolis. Archeology’s InteractiveDig (http://www.archaeology.org/interactive/hierakonpolis/field09/3.html), Archaeological Institute of America.

Ulrich, Roger Bradley (2007). Roman
woodworking. New Haven, CT: Yale University Press.

Welsh, Peter C. (1966). “Woodworking tools, 1600-1900”, Bulletin of the United States National Museum, pp. 177-277.

Colonial Williamsburgh Foundation (website, s.d.), Auglets, gimlets and braces. http://www.history.org/almanack/life/tools/tlaug.cfm.

Historical Folk Toys (website, 2004). Indian pump drill. http://www.historicalfolktoys.com/catcont/6007.html.

Boat Mills: Water Powered, Floating Factories

Boat mills, bridge mills and hanging mills were almost as widespread as windmills.

The waterwheel was seen as the most important power source in the world, from the Middle Ages to the end of the nineteenth century. When smaller streams became saturated, medieval engineers turned their attention to larger rivers, eventually leading to the development of the hydropower dams that still exist today.

Lesser known are the intermediate steps toward that technology: boat mills, bridge mills and hanging mills. Boat mills had already appeared in 6th century Italy and spread all over the world. Most of them remained in use up until the end of the 1800s, with some of them surviving well into the 1900s.

Curious Things

Until recently, boat mills, also known as ship mills or floating mills, were largely thought of as a curiosity, a mere footnote in the long history of water power technology. Today some historians think that they were almost as widespread as windmills – although it should be noted that windmills, contrary to popular belief, were less common than watermills. The first monographs of boat mills only appeared in 2003 and 2006. They contain, among many other new facts, the discovery of three tiny ship mills on a famous medieval painting from 1435 (Madonna of Chancellor Rodin by the Flemish painter Jan van Eyck). Nobody had noted them before, or weren’t cognisant of exactly what they were.

Granted, boat mills are curious things. Some look like paddle-wheel riverboats, but in fact they are exactly the opposite. A waterwheel can be used in two ways: to create energy from moving water, as is the case with the water mill, or to apply energy to water with the result of motion, as is the case with a paddle wheel boat. The boat mill has the outside appearance of the latter, but it works just like a water mill. Basically, a ship mill is a water mill (waterwheel + milling house) built on a floating platform, moored to the river bank or anchored in the stream. The flowing water turns the water wheel, which in its turn drives the milling machinery. Ship mills could be used as single units, or fastened together side by side.

Advantages of Ship Mills

Why build floating water mills when you can just as well construct a fixed water mill on the bank of a river? There were several good reasons. Although water is a much more reliable power source than wind, you cannot always count on it. Rivers rise and fall with the seasons and with the prevailing weather, while the axle of the water wheel remains at a fixed height. On smaller streams this variability could easily be mitigated by creating a small dam and sluice gates, forming a mill pond to even out natural flow conditions. An overshot wheel could also be used, especially in hilly regions. This wheel receives water from above via some kind of aqueduct and is more efficient (50 to 65%) than an undershot wheel (20 to 30%).

However, constructing dams and sluice gates would be much more difficult to achieve on a stream 100 metres wide and 10 metres deep. Overshot wheels could not be used. Since the water level in many large rivers could vary substantially, a fixed watermill on the bank of a river could thus easily end up with its blades above the water, rendering it useless. Conversely, rising water levels could partly or completely submerge the wheel, again rendering it useless (contrary to a modern turbine, which can operate fully submerged). Even less extreme variations of the water level could seriously decrease the efficiency of a fixed water wheel. An undershot wheel derives its power entirely from the impulse of water, not complemented by gravity as is the case with an overshot wheel.

In combination with a mill pond, the water could be directed at an optimal angle to the undershot wheel in order to obtain maximum efficiency. On a large river, where no mill pond was available, this was not possible – further decreasing the already limited efficiency of the undershot wheel. Floating watermills solved these problems. They simply followed the water level, keeping the undershot wheel always at a continuously ideal position. The result was a power source that was available 24 hours a day and 365 days per year (with the exception of extreme weather events). Furthermore, ship mills could be located at other parts of the stream where water velocity was higher than close to river banks, increasing their power output. Last but not least, ship mills also overcame the problem of overcrowded river banks, an especially important consideration for cities.

Two Types of Boat Mills

Basically, there were two main types of boat mills. One type was composed of two hulls with a water wheel in between, while the other type consisted of one hull with two waterwheels on both sides (or, sometimes, one waterwheel on one side). The boat mill with two hulls, somewhat resembling a catamaran, was by far the most efficient and powerful of both models. The two hulls channelled the water onto the wheel, increasing the impulse. A boat mill with a single hull did exactly the opposite.

Furthermore, the floating mill with two hulls could support much larger wheels than the type with one hull, again increasing the power output. Thirdly, the double hull allowed for a system of control gates to regulate the amount of water hitting the wheel, thereby making it possible to better control the speed of the machinery inside the milling house, or to stop the wheel altogether. This system also protected the wheel against driftwood. Finally, a boat mill with two hulls was also more stable.

One of the hulls was much wider than the other one. It housed the milling machinery (mill stones and gears), the grain to be ground, and – in the case of larger ship mills – the boat miller residence. In the case of smaller ship mills, this house stood on the bank of the river. The smaller pontoon only served to carry the axle. The main hull and the pontoon were connected at the front and the rear with strong beams. Balancing the floating mill was done by loading stones in the pontoon.

The large hull was always on the side of the river bank for easy accessibility – this meant that ship mills with two hulls were designed with a specific location in mind: the left or the right bank of the river (on the aforementioned painting by Jan Van Eyck, this fact was overlooked by the artist). If it was moored on the river bank, the mill was accessible by a stone or wood bridge or gangway. Sometimes pack animals were used to deliver the grain and to take away the flour. If the boat mill was located midstream, it was only accessible via small boats.

Boat mills, which were built almost entirely out of wood, could be impressive structures. Generally, they were 10 to 15 metres long, while the longest ship mills described measured 20 metres and more. The large hull was usually 5 to 8 metres wide, the pontoon 2 to 3 metres. Both were mostly built in a rectangular form. A ship mill could be more than 6 metres tall and some had two or even three floors. However, while some floating mills were huge and outstandingly crafted, others were rather small and sometimes very crude contraptions. The life expectancy of a boat mill could be between 30 and 50 years, with the wheel itself lasting for a decade. But some ship mills did not last even that long, rotting from the inside or simply falling apart.

Huge Wheels

While conventional water mill wheels were seldom wider than one metre, the wheels of ship mills with two hulls could be up to six metres wide, with the axle up to ten metres long. Medieval engineers explored the limits – wooden wheels could not be built larger than this if they were to retain their strength. The huge wheels had a diameter of about five metres and turned at three to five revolutions per minute, depending on the velocity of the stream. They delivered between three and five horse power at the shaft. Ship mills with one hull could not support these wide wheels and delivered much less power. Among the lesser common types of boat mills were those with two water wheels in between the main hull and the pontoon, allowing them to operate two mills at the same time. They required very long axles, which were not always easy to find. Placing the two wheels one after the other resolved this, at the expense of decreased efficiency.

From the 15th century onwards, many conventional water mills started performing tasks other than milling grain, but most boat mills did not. Almost all of them were corn mills. There were a few exceptions. Karel Broes, the Flemish author of the 2003 monograph, lists a few floating paper mills, sawmills, fulling mills, oil mills, polishing mills, minting mills and cotton mills. Some of the more recent ship mills ended their life as an energy source for power generation. In his standard work on the history of Chinese technology, Joseph Needham cites a 16th century Chinese writer who describes trip hammers mounted on boat mills to make paper:

In Liang-chiang there were many ship mills, which work on the same principle as the water raising wheels, and are all anchored in the rushing water. The operations of grinding, pounding, and shifting (bolting) are all carried out by the use of water power. The boats make a noise ‘ya-ya, ya-ya’ incessantly.

Origins

Few inventions from Antiquity can be dated as precisely as the ship mill. In 536 or 537 AD the Goths besieged Rome. In an attempt to starve the Romans, they cut the fourteen aqueducts that delivered water to the city. This did not deprive the Romans of drinking water because the Tiber flowed through the walled city. But the aqueducts were the power source for the water mills that ground the grain for the whole city. However, the Byzantyne general Belisarius, then in charge of defending the city, came up with the luminous idea of the boat mill. The event was accounted for in detail by the contemporary author Procopius:

When the water was cut off and the mills stopped, and cattle could not grind, the city was deprived of food, and provision could hardly be found for the horses. But Belisarius, an ingenious man, devised a remedy for the distress. Below the bridge across the Tiber he extended ropes, well-fastened across the river from bank to bank.

To these he affixed two boats of equal size, two feet apart, at a spot where the current flowed with the greatest velocity under the arches; and placing mill stones in one of the boats, he suspended machines by which they turned in the water-space between them. He also contrived, at certain intervals on the river, other machines of the like kind, and these being put into motion by the force of the water, drove as many mills as were necessary to grind food for the city.

After that, the Roman empire did not last much longer – the Goths took Rome in 562 – but the ship mill would remain in use for another 1,400 years, with the last one only disappearing in the 1990s. Remarkably, during all those centuries, boat mills hardly changed. Those that could still be seen during the second half of the 20th century looked very similar to those illustrated in the Middle Ages (no earlier images of ship mills have survived).

Distribution of Ship Mills in Europe

After its initial success in Rome, the ship mill became a common sight on the Tiber and quickly caught on all over Europe. During the 6th century they also appeared in Switzerland (Geneva) and France (Paris and Dijon). During the 800s, boat mills showed up on the Rhine in Strasbourg (France) and Mainz (Germany). At the end of the tenth century, they were noted on the Kur in Georgia. They reached Venice and the Balkans in the 1000s and Spain in the 1100s. Toulouse (France) had at least 60 ship mills on the Garonne in the 12th century, milling all the grain for the city. Paris counted 70 to 80 boat mills on a one mile stretch of the Seine in the 1300s. In 1493 there were 17 floating mills on the Rhône at Lyon, growing to 20 by 1516 and to 27 by 1817.

The Elbe, flowing through Germany and the Czech Republic, once counted 500 boat mills. There were also hundreds of ship mills on the Danube: 62 in Vienna (Austria), 88 in Budapest (Hungary) and a non-specified amount in Slovakia, Croatia, Serbia, Bulgaria and Romania. The Mur, a river that flows mainly through Austria and Slovenia, had over 90 boat mills. Ship mills can even be seen on 17th century city plans of Moscow. In her 2006 monograph, Daniela Gräf could find proof of almost 700 specific locations, mainly on the Seine, Loire, Garonne, Rhône, Rhine, Weser, Elbe, Oder, Danube, Po and their tributaries, on which one or more boat mills have existed at one time or another. The total amount remains unknown for now.

Floating mills did not show up everywhere, though. The Scandinavians and the English never warmed up to the idea. Attempts to build them on the Thames in London failed twice in the 16th century and again in the 18th century. The reasons for this are not well known. In Flanders and in the Netherlands, boat mills never really gained popularity – not more than a dozen were operated from the 15th to the end of the 17th century. In this case the cause is clear: the flow of the rivers in the Low Countries is too low and water power in general was of limited use. Because the region had much better wind conditions, it became an important center of windmill technology.

Distribution of Ship Mills Outside Europe

Boat mills appeared in the Islamic world at the end of the 9th century, where they were employed along the Tigris and Euphrates rivers. These large floating mills were equipped with four stones and could each produce around 10 tonnes of flour per 24 hours. Each mill could grind grain for around 25,000 people, which means around 60 of them were needed to feed the then estimated 1.5 million people in Baghdad. Nothing yielding this scale of mechanised corn milling was known in any European country at that time, notes Terry Reynolds in his book on the history of the vertical water wheel. In 1148, Ibn Jubayr described the ship mills across the river Khabur in Upper Mesopotamia “forming, as it were, a dam”.

Joseph Needham found references of ship mills in Chinese literature in 737 (when “Ordinances of the Thang department of waterways forbid shipmills on the river and streams near Loyang as if they were something very well known”), 1170, 1313, 1570, 1628 and 1637. In 1848, traveller Robert Fortune found a whole colony of ship mills near Yenchow in northern Fukien. Here is his description:

The stream was very rapid in many parts, so much that it is used for turning the waterwheels which grind and husk rice and other kinds of grain. At first I thought it was a steamboat, and was greatly surprised. A large barge or boat was firmly moored by stem and stern near the side of the river, in a part where the stream ran most rapidly.

Two wheels, not unlike the paddles of a steamer, were placed at the sides of the boat, and connected with an axle which passed through it. The boat was tatched over to afford protection from the rain. As we got further up the river, we found that machines of this description were very common.

At the beginning of the twentieth century, Worcester made detailed engineering drawings of the ship mills still in action around the Chinese city of Fouchow. These carried four waterwheels on two axles.

Boat mills also opened up the possibility of generating power from coastal areas and estuaries, because they could be used as tide mills. The first one was described in 960 AD and was located on a canal of Basra in Southern Iraq. It could be that the early ship mills in Venice were tide mills, too, though nobody knows for sure. When a boat mill was used as a tide mill, its wheels would be pushed in one direction when the tide came in, and in the other direction when the tide went out. They could not be used for more than 10 hours per day. Very few of them were built – dams and tidal reservoirs were more common options to harvest tidal energy.

Bridge Mills

Medieval millers quickly learned that the output of boat mills could be increased when they were anchored or moored close to islands, sand banks or man-made structures – most notably bridges. The wide piers and short arch spans of medieval bridges greatly increased the velocity of the stream at these locations. Positioning a ship mill underneath the arches of a bridge or just downstream from it became very popular practice during the Middle Ages.

Reynolds notes that when the Grand Pont, a masonry bridge in Paris under which more than a dozen ship mills were located, was destroyed at the end of the 13th century, it were the owners of the mills who quickly built another (wooden) bridge to facilitate the operation of their boat mills. From this practice came the evolution of the bridge mill, which probably appeared in the 12th century (the first description comes from Cordoba, Spain). Bridge mills did not float – they were built as part of a bridge with the milling machinery built on top of the bridge itself. Unlike boat mills, they required some mechanism to alter the position of the wheel as the water level changed.

In most cases the mill was suspended from the bridge by chains which could be adjusted by a capstan arrangement or a treadmill. Bridge mills had sluice gates to control the flow of water and to protect the wheel against driftwood. From the 16th century onwards, quite a few ship mills were replaced by bridge mills.

Hydropower Dams

The bridge mill was an intermediate step in the process of adapting the waterwheel to large rivers, culminating in the hydropower dam that we know today, as described by Terry Reynolds in his study on the history of the vertical water wheel:

The hydropower dam and its adjunct, the power canal, presumably evolved from the boat mill and the bridge mill. The boat mill had been an attempt to adapt the vertical wheel to the natural flow of streams. The bridge mill had been a further step in that direction, but it had also demonstrated that natural conditions of flow could be significantly improved by human artifices.

In one sense, the medieval river bridge, when combined with either boat or bridge mill, was a primitive form of hydropower dam, an intermediate step between the unassisted boat mill and the full-scale hydropower dam. Intentionally designed hydropower dams and the power canals frequently associated with them, however, went a step further. The boat mill and, to a lesser extent, the bridge mill had adapted the water wheel to natural stream conditions. The hydropower dam did the reverse. It adapted the stream to the water wheel.

Hanging Mills

A variant of the bridge mill was the hanging mill or suspended mill, which was not suspended from a bridge but from a specially designed structure (bridge mills are sometimes called hanging or suspended mills, too). It worked in a similar manner but did not offer all the advantages of the bridge mill – capital costs were higher and boats were required to access them. Their commonality was their relatively high power output, since they could support multiple waterwheels and could be built much larger than boat mills.

Less is known about these suspended mills, and most of the available data is limited to France. Three large hanging mills were built in Paris on the Seine during the 17th century. They took care of the water supply for the city, pumping water from the river. The Pompe du Samaritaine was built in 1608 and the Pompe du Pont Notre Dame – which actually consisted of two suspended mills with a water tower in between – was built in 1670, following a severe water shortage. They had a power output of respectively 8.7 and 18.6 HP.

Large suspended mills (of a different type) were also built outside of France, notably in Germany (where they were called Panstermühlen) from the 16th century onwards. Beyer describes one with multiple wheels that was 27 metres long, 15 metres wide and 18 metres high. It was built on the river bank, but contrary to a conventional fixed water mill the wheels could be moved up and down. In the 19th century, yet another type of hanging mill appeared in Romania and Poland (the Alvan). Hanging mills were also built in the Far East from the 15th century onwards.

Accidents

Bridge mills and hanging mills had another important advantage over floating mills: safety. Right from the beginning, ship mills caused problems. During heavy floods or storms their moorings could break. The mills were carried away – sometimes with the people still inside – and smashed into boats, docks, bridges or other ship mills. They could get stuck in the arch of a bridge, damming the river and thus causing the waters to rise even higher. Floating ice could have similar consequences. Ship mills were not built with any means of proper navigation, so when they broke loose they were out of control. They could only navigate in calm weather.

Even under normal weather conditions boat mills formed a threat, especially for navigation. A floating mill required very secure anchoring, in order to avoid the accidents described above. Usually the method used was to hammer heavy wooden posts into the riverbed – often angled upstream – on which to fix their chains. These posts were a hazard to other boats, especially when the ship mill had been moved to another location in the meantime. Bridge mills and hanging mills did not pose these risks. Furthermore, their wheels could be taken out of the water when there were floods or ice, preventing damage to the mill. They were also more stable – another drawback to ship mills was that they sometimes delivered a product of inferior quality, due to the instability of the water. This might explain why most ship mills were only used to grind grain. Finally, bridge mills and hanging mills were also easier to maintain than boat mills.

The Demise of the Ship Mill

In some regions boat mills were discontinued rather quickly. The 60 floating mills that were installed in Toulouse in the 12th century had disappeared less than a century later. They were replaced by three dams on which 43 fixed watermills were erected. The largest of these was the 400 metres long diagonal Bazacle dam, which was in operation by 1177 and remained the largest hydropower plant for quite some time. However, this drastic and early transition seems to have been an exception rather than the norm. Many more hydropower dams were built, and more boat mills were replaced by bridge mills or hanging mills, but in most European countries and in the near East ship mills remained in use well into the 1800s.

The majority of boat mills were discontinued between 1770 and 1870, which is no coincidence. Around 1780, the first steam river boats appeared and river navigation became ever more important. The use of ship mills was restricted by law in Austria in 1770 and in Paris in 1787. The construction of new ship mills was outlawed on the Rhine in 1868. In response to strict regulations in Slovakia at the end of the 19th century some boat mills were converted to fixed water mills on stilts – yet another variation. In Paris, only four ship mills were left in 1800. The last boat mills on the Seine, the Loire and the Rhône disappeared respectively in 1840, 1842 and 1894. The last ship mill in Cologne was discontinued in 1847. At the beginning of the 1800s, there were still about 20 ship mills active on the Tiber, milling grain for a population of 158,000. At the end of the century, the last one disappeared. On the other hand, Vienna (Austria) still had 55 ship mills in 1870. In China they were used up to the end of the 19th century.

Boat Mills in the 20th Century

On some rivers boat mills could still be seen in the 1900s. During the first half of the century, working boat mills could be found in Georgia (Tiflis, 9 mills operating in 1909), Czech Republic (Lovosice, 1911), France (on the river Doubs, 3 mills operating in 1914), Iraq (Tekhrit, where they were used at least until 1917), Italy (10 boat mills in Verona in 1914, the last one stopped working in 1929), Turkey (1920), Germany (several locations, until 1926), Japan (1933), Slovakia (1937), Hungary (Tiszán, 1940) and Austria (Misseldorf, until 1945).

Bosnia had 27 mills left in 1950 with the last one disappeared in 1966. In Romania, 35 ship mills were still in use in 1957, and 8 of these were still working in 1968. Finally, the French historian Claude Rivet found a working ship mill on the Morava at Kuklijn (Serbia) in 1990, which was discontinued shortly afterwards. This seems to have been one of the last working authentic boat mills. Since then, around a dozen reconstructions have been built. ←

Last ship mill on the Rhine, 1925.

Ship mills on the Seihun, Adana, Turkey, around 1920. Postcard collection Ton Meesters, Breda, the Netherlands.

Boat mills, circa 1600.

Boat mills on the Tiber, Italy.

Ship mills on the Rhine, detail from Ansicht von Köln by Anton Woensam, 1531.

Ship mills on the Kur in Tiflis, Georgia, around 1900. Postcard from the collection of Ton Meesters, Breda, the Netherlands.

Boat mill. Encyclopédie Diderot, 1751.

Boat mill. Encyclopédie Diderot, 1751.

A stationary tugboat. Encyclopédie Diderot, 1751.

A ship mill with two hulls could support larger wheels. Johann Matthias Beyer.

Early twentieth-century drawing of a ship mill from the Chinese city of Fouchow, carrying four waterwheels on two axles.

Drawing of a suspended mill in Germany.

Bridge mill, suspended by chains. Zonca.

A hanging mill in France, 1910.

The Pompe du Pont Notre Dame, which was demolished in the second half of the 19th century, here on a 1756 painting by J.B. Raguenet.

References

Broes, Karel (2003). “Over schipmolens en andere onderslagmolens met in hoogte verstelbare wateras”, Molenecho’s. Tijdschrift
voor Molinologie, Vol. 31, No. 3 (July-Octobre).

Reynolds, Terry S. (1983). Stronger than a hundred men: a history of the vertical water wheel. Baltimore; London: The Johns Hopkins University Press.

Gräf, Daniela (2006). Boat mills in Europe from early medieval to modern times. Dresden: Bibliotheca Monologica.

Needham, Joseph (1971). “Wheels ex-aqueous and ad-aqueous; ship-mill and paddle-boat in east and west”, in Science and Civilisation in China, Vol. 4: Physics and Physical Technology, Part 3: Civil Engineering and Nautics. Cambridge: Cambridge University Press.

Beyer, Johann Matthias (1735). Theatrum Machinarum Molarium, Oder Schau-Platz der Mühlen-Bau-Kunst. Dresden: Walther.

Sturm, Leonhard Christoph (1718). Vollständige Mühlen-Baukunst. Augspurg: Jeremias Wolff (publisher).

Kranz, Horst (1991). Die Kölner Rheinmühlen: Untersuchungen zum Mühlenschrein, zu den Eigentümern und zur Technik der Schiffsmühlen. Aachen: Alano Rader Publikationen.

Forbes, R. J. (1965). Studies in Ancient technology (vol. 2). Leiden: Brill.

Diderot et d’ Alembert (1751). L’Encyclopédie.

Rivals, Claude (2000). “Histoire d’une technique. Le dernier moulin à nef”, L’Histoire, No. 153.

Rivals, Claude (2000). Le moulin et le meunier. Mille ans de meunerie en France et en l’Europe. Portet-sur-Garonne: Empreinte.

Beaudoin, Francois (1993). Paris à gré d’eau. Arcueil: Anthèse.

Wikipedia, The Free Encyclopedia, s.v. “Schiffmühle”, http://de.wikipedia.org/wiki/Schiffm%C3%Bchle.

Lucas, Adam (January 01, 2006). WIND, WATER, WORK Ancient and Medieval Milling Technology. Technology and Change in History, 8.

Kawakami, Kenjiro (1982) A survey of water mills in Japan. Transactions du V° Symposium TIMS, p.293.

Recycling Animal and Human Dung is the Key to Sustainable Farming

Flushing the water closet wreaks ecological havoc, deprives agricultural soils of essential nutrients and makes food production dependent on fossil fuels.

For 4,000 years, human excrements and urine were considered extremely valuable trade products in China, Korea and Japan. Human dung was transported over specially designed canal networks by boats. Thanks to the application of human “waste” products as fertilizers to agricultural fields, the East managed to feed a large population without polluting their drinking water. Meanwhile, cities in medieval Europe turned into open sewers. The concept was modernized in late 19th century Holland, with Charles Liernur’s sophisticated vacuum sewer system.

Broken Cycle

The innocent looking water closet breaks up a natural cycle in our food supply. Basically, it turns extremely valuable resources into waste products. When we grow crops, we withdraw essential nutrients from the soil: potassium, nitrogen and phosphate, to name but the most important. During the greater part of human history, we recycled these nutrients through our bodies and returned them to the soil, via excreta, food trimmings and the burial of dead. Today, we flush them mostly into the sea.

This is problematic and unsustainable, for three main reasons. To start, dumping sewage in rivers, lakes and seas kills fish and makes fresh water undrinkable. This can only be avoided by extending the water closet and the already very costly sewerage network with an equally expensive infrastructure of sewage stations (which does not completely eliminate the detrimental effect on water life).

Secondly, we need artificial fertilizers to keep our soil fertile. In 2008, almost 160 million tonnes of inorganic fertilizers were used worldwide. Without these, our agricultural soils would lose their fertility in just a few years time, followed by an inevitable collapse of food production and human population. A third problem is that the water closet logically consumes large quantities of fresh water to flush everything “away”.

Fresh water production, the construction and maintenance of sewers, the treatment of sewage (and sewage sludge), and the production of inorganic fertilizers are all energy-intensive processes. Nitrogen (which makes up more than half of total fertilizer consumption) is abundantly available in air, but to convert it to a useful form the gas has to be heated and pressurized. The energy for this (polluting) process is delivered by natural gas or (in China) by coal plants.

Potassium and phosphate have to be mined (up to depths of several thousands of feet) and transported. It takes more than 150 million tonnes of phosphate rock to produce our current yearly supply of 37 million tonnes of phosphate fertilizer, and 45 million tonnes of potash ore to produce 25 million tonnes of potassium fertilizer. Both operations are energy intensive and pollute the environment.

Moreover, while potassium is widely distributed and abundantly available (we have enough economically obtainable reserves to last 700 years at our current consumption rate), phosphorus is not. Ninety percent of global phosphate reserves are only found in a handful of countries, and economically recoverable reserves large enough to meet agricultural demand are estimated to last for only 30 to 100 years. Reserves are much larger if mining phosphates from the seabed is included, but this would be extremely energy-intensive, further deterioriating the sustainability of the food and sanitation system.

The only way to get nutrients from sea to land is via marine bird droppings – which is of course in very short supply – or by eating fish or seafood. However, once we have digested our fish and chips, the nutrients filter down to the sea via the sewer network.

A Sign of Civilization

The existence of the water closet and the accompanying sewer system is seldom questioned. It is viewed as an obvious technology and generally regarded as a sign of civilization – countries that do not have such a system today are considered retarded or backward. The reason for this is because we have been conditioned to believe that the water closet and the sewer system are the only alternatives to stench and disease.

Following the demise of the Roman Empire (with its early sewers and water closets) and right up to the end of the nineteenth century, the concentrated and unorganised distribution of human excrements in groundwater, city canals and rivers brought recurrent deadly epidemics of cholera and typhoid fever throughout the western world. These were caused by drinking water contaminated with faeces. People answered nature’s call on the streets or emptied their honey buckets in backyards, open courtyards, badly sealed cesspools or surface waters – methods that were not conducive to healthy living in densely populated cities. Water closet and sewer system have solved this, at least in the rich world, and nobody wants to go back to the miserable hygienic conditions of those times.

Chinese Agriculture

However, as obvious as it seems to us today, the water closet is not the only possible answer to the problem of sanitation. There are other, much more sustainable methods to separate human waste from drink water supplies. To start with, the grim sanitary conditions of the Middle Ages and the early Industrial Revolution were a purely western phenomenon. At the turn of the twentieth century in the East, the water in Chinese rivers was safe to drink. The Chinese were as numerous as the Americans and Europeans at the time, and they had large, densely populated cities, too. The difference was that they maintained an agricultural system that was based on human “waste” as a fertilizer. Stools and urine were collected with care and discipline, and transported over sometimes considerable distances. They were mixed with other organic waste, composted and then spread across the fields.

That’s killing two birds with one stone: no pollution of drinking water, and an agricultural system that could have lasted forever. In fact, it did last 4,000 years, which is considerably longer than even our most abundant resource – potassium, with 700 years of reserves – will allow. The Chinese agricultural system, which was also applied in Korea and Japan, is extensively described in Farmers of Forty Centuries, a report of a study trip by the American soil scientist F. H. King. The book was published in 1911, around the time of the discovery of the Haber-Bosch process that would lead to the breakthrough of cheap artificial nitrogen fertilizer. King devoted an entire chapter to the collection and use of human fertilizer by the Asians. Joseph Needham also gives an account of the method, in volume VI:2 of Science and civilization in China, citing various earlier sources. More recently, Duncan Brown talks about the Chinese system in his book Feed or Feedback: Agriculture, Population Dynamics and the State of the Planet (2003).

Dung Traders

When King visited China, the population was estimated at about 400 million adult inhabitants, compared to some 400 million inhabitants in Europe and 100 million inhabitants in the US. The stools and urine of those 400 million people were collected in terracotta jars, with air-tight seals. The matter was gathered from every home, from the tiny country villages to the great cities. In some cities, special canal networks and boats were constructed for this purpose. This was the case in Hankow-Wuchang-Hanyang, for example, a city with almost 1.8 million inhabitants living in an area of only 6.5 square kilometres. You could thus argue that the Chinese did have a water carriage sewer network, though the difference to ours is stark.

Around the time of King’s visit, every year in China more than 182,000,000 tonnes of human manure was collected in cities and villages – 450 kilogram (900 pounds) per person per year. This was good for a total of 1,160,000 tonnes of nitrogen, 376,000 tonnes of potassium and 150,000 tonnes of phosphate which was returned to the soil. In 1908 Japan, 23,850,295 tonnes of humanure was collected and given back to the soil. Shanghai traded and distributed the yield of its inhabitants over a specially designed canal network using hundreds of boats, a trade that brought in 100,000s of dollars every year. Human manure was considered a valuable commodity. In 1908, a Chinese business man paid the city $ 31,000 (this would be more than $ 700,000 today) to obtain the right to remove 78,000 tonnes of humanure per year from a region of the city to sell it to the farmers on the countryside.

In Japan, which was much more urbanized than China, people paid less rent when they left their landlord better quality excrements. King describes loads of human dung taken from Tokyo and Yokahama “carried on the shoulders of men and on the backs of animals, but most commonly on strong carts drawn by men, bearing six to ten tightly covered wooden containers holding forty, sixty or more pounds each”. On the Japanese countryside, it was not unusual to see signs that invited passers-by to please answer nature’s call on site. The farmers used the product to manure their fields. The practice of recycling human dung in Asian countries repelled some foreign visitors. The Portuguese explorer Fernam Mendez Pinto wrote in 1583:

You must know that in this country there are many of such as make a trade of buying and selling mens Excrements, which is not so mean a commerce among them, but that there are many of them grow rich by it, and are held in good account. They which make a trade of buying it go up and down the streets with certain Clappers, like our Spittle men, whereby they give to understand what they desire without publishing of it otherwise to people, in regard the thing is filthy of itself; whereunto I will adde thus much, that this commodity is so much esteemed among them, and so great a trade driven of it, that into one sea port, sometimes there comes in one tyde two or three hundred Sayls laden with it.

The 4,000 year old closed-loop system vanished with the arrival of artificial fertilizers, which were imported from the West during the first decades of the twentieth century. Today, China is the largest consumer of inorganic fertilizers with 28 percent of total world consumption. Asia as a whole now uses more than half of the world’s artificial fertilizer.

Night Soil Collection in Europe

The collection of human “waste” also occured in Europe, be it for a much shorter time and on a much smaller scale. The second half of the nineteenth century marked the end of a predominantly agricultural period in Europe; migration to the cities accelerated and the problem of sewage disposal got much worse. At the same time, health experts started to realize that cholera and typhoid fever were the consequences of drinking contaminated water. Since agriculture was increasingly short of animal manure, it appeared that both problems could be solved at the same time. The first system, which was set up in several countries and cities, is generally known as night soil collection and reminds of the Asian method.

Dung and urine were accumulated in movable wooden receptacles beneath the privy seat and mixed with earth, ashes or charcoal to prevent offensive odours. Night soil collectors came by at more or less regular intervals (mostly at night, hence the name) to pick up the merchandise. This happened either by emptying the full tubs into a cart and giving them back immediately (which meant the cleansing had to be done by the users), or by placing the full tubs in a wagon, switching them for fresh ones (which meant the cleansing had to be done by the scavengers). The empty tubs were replaced under the privy seat, and the cargo was transported via horse and cart to a collection point outside the city. There it was converted into compost for use in agriculture.

Unfortunately, the collection and transport of the waste was not as reliable, efficient and sanitary as was the case in China, Korea or Japan. All was good when air-tight containers were used, but this was not always done. When open carts were applied, the transport caused waste and foul smell. Sewage was spilled while carrying the tubs down the stairs and while emptying them into the carts. Moreover, the collection did not always happen that frequently, especially in poorer neighbourhoods. Nevertheless, the wooden tub system was an improvement over the comparitive disorder of nightsoil collection in Europe. Throughout the Middle Ages, so-called dung farmers gathered human and animal excrements from streets, backyards and cesspools and sold these to farmers who applied them to their fields. The problem was that these scavengers needed to collect enough dung before they could sell a cartload. Duncan Brown cites Cipolla, who describes the situation concisely:

The most pathetically tragic aspect of this business was that of the people, whose poverty was so abject that they collected the manure they found in the streets where they kept it at their homes until they had accumulated a sufficient quantity to sell.

There were exceptions, notably in Flanders, where an organized nightsoil collecting system that reminds of the Chinese method was set up as early as the Middle Ages. Around the town of Antwerp, the management of organic wastes (human excrements, dung of city horses, pigeon dung, canal mud and food scraps) had become a significant industry by the sixteenth century. By the eighteenth century there were great stores along the river the Schelde where the excrements from Dutch towns were transported by barge.

The Vacuum Sewers of Charles Liernur

A second collection method was pioneered by Dutch engineer Charles Liernur in 1866. His vacuum sewer system combined the comfort of today’s water carriage sewer network with the ecological and manurial advantages of the earlier scavenging methods. A closet inside every home was connected to an underground small diameter pipeline infrastructure, and the stools and urine immediately left the house following deposition. The crucial difference with today’s technology, however, was that the Liernur system did not use water but atmospheric pressure as a transport medium. This meant that it avoided the dilution of the manure by the admixture of water, thus preserving its value as a fertilizer – which was Liernur’s explicit intention.

On the other hand, the vacuum sewer system did away with the need for scavengers to visit every house, lugging around buckets of poo and pee, and disturbing everyone’s sleep. It was a clear improvement on the night soil systems, including the one used in Asia. Dutch cities were equipped with the Liernur system: Leiden in 1871, Amsterdam in 1872 and Dordrecht in 1874. Initially, only a couple of thousand homes were connected to the vacuum sewer network, but in Amsterdam the system was expanded substantially. At the end of the nineteenth century, about 90,000 Amsterdam inhabitants were linked to the Liernur sewer network, some 20 percent of the population.

In Amsterdam and Leiden, the system remained in operation for almost 40 years. The Liernur system was also introduced on a smaller scale in Prague (Czech republic), Trouville sur Mer (France), Hanau (Germany) and Stansed (England). The system in Trouville, installed in 1892, was operated until 1987. Today, the method is still being used in ships, trains and airplanes. The French designed their own version of the Liernur system – the Berlier system. It was introduced in 1880 for a trial period in Lyon, where it successfully removed sewage over a distance of four kilometres (2.5 miles). In 1881, a five kilometre network was introduced for trial in a Paris neighbourhood. The French took the trials very seriously: the sewage was observed by placing glass pipes at various points. The Berlier system, which was technically superior to the Liernur system, worked flawlessly: the thousand soldiers in the barracks of Pépinière, where it was in operation, were the only troops in Paris that were not affected by a serious typhoid epidemic.

The Arrival of the Water Closet

In spite of the technical success, the Berlier system never ascended beyond the experimental stage. The Dutch Health Advisory Board advised a general, national introduction of the Liernur system in 1873, following the successful operation in Amsterdam, but this did not happen either. Liernur designed plans for other cities in Europe (Paris, Berlin, Stockholm, Munchen, Stuttgart and Zurich) and in the US (Baltimore), but these were never realised. There were several reasons why the pneumatic systems did not became the standard sewerage systems of today. Firstly, there was the arrival of the water closet and the waterworks. In the Netherlands, a growing number of people connected a water closet to the Liernur system, diluting the stools and urine in such a matter that their agricultural value declined considerably.

Even before this happened, the sale of the sewage for use as manure did not give the profits that were expected. Health experts advanced that profits should not be the first aim of a sanitary system, but the problem was that Liernur himself had stressed financial profits as an important advantage of his system. This had attracted investors, and they promptly left the technology behind when they started to lose money. An important problem, not only in the Netherlands but throughout the western world, was the growing size of cities. Both the night soil system and the more sophisticated methods were eventually beaten by the logistics of maintaining the practice in huge cities supported by far away farms. The last blow for the vacuum sewer system was the appearance of inorganic fertilizers after a cheap production method was found in 1910. The shortage of fertilizers in agriculture was “solved”.

Because cities had started building water carriage systems for the discharge of storm drain water, the next logical step was to allow the discharge of sewage via the same network. Basically, this was a step backwards: excrements were again drained on surface waters, not necessarily in the immediate surroundings but a few miles further downstream. It took another 70 years before sewage stations became (relatively) common in the rich world.

Only Three Future Possibilities

If we want to restore the natural cycle of our food supply, there are only three technological possibilities. We could develop a modern variant of the scavenging method using composting toilets, in which the stools are collected from individual homes together with other organic waste products. Urine could go to a separate tank that is emptied once a year by a tanker (this method exists in some Dutch and Swedish residential areas where people use so-called urine separation closets). Or, we could develop a modern variant of the Liernur or Berlier system, in which the sewage is collected automatically, but without the use of water. Vacuum sewer systems have found a limited application in some new housing estates since the 1960s and 1970s. A few hundred systems are in operation in the US, the UK, Australia, Germany, the Maledives, Southern Africa and the Middle East.

The installation of a vacuum sewer system is twice as cheap as the construction of a traditional sewer system. A vacuum system is also faster to construct and easier to maintain: it consists of much smaller diameter tubes that have to be laid less deep into the ground – a narrow trench in the road-surface suffices. There is a third techno-fix, but it is many times more expensive than the other two: using the diluted sewage from our water carriage system as a fertilizer. Basically, this adds another layer of costly infrastructure and complexity on top of an already very costly and complex system. Diluted sewage not only has to be dried, but also purified. This is because sewage sludge does not only contain human waste but also many other (including toxic) waste resources, both from households and factories. Interestingly, when we remove urine and excrements from the sewer system, we might as well eliminate the water carriage sewer system altogether, further obtaining substantial cost and energy savings. There are workable alternatives for the removal of storm water (basically reducing paved surface) and for the local treatment and re-use of grey water.

Composting

Human faeces and urine can only be used as a fertilizer following further treatment. This was an already known fact by early Chinese agricultural writers, who warned that untreated humanure could “burn and kill plants, rot the shoots and harm human hands and feet”. Today we know it also carries more severe health risks. F. H. King and Joseph Needham praise the composting efforts of the early Chinese, who often combined their privy with the family pigsty. However, Duncan Brown is more critical of their composting techniques. The health advantages that the Chinese gained by keeping their drinking water supplies clean, were partly offset by the transmission of diseases via food crops:

Gastro-intestinal diseases were endemic throughout the region. In Korea and Japan, fluke diseases were common because of the practice of eating raw fish grown in ponds fertilized with human excrement. But those diseases could have been largely avoided with a better understanding of their nature and modes of transmission. If properly used, devices like the relatively modern sceptic tank, the more modern oxidation tank or the so-called composting toilet can avoid the danger of gastro-intestinal diseases previously associated with the use of human excrement as manure.

A process of composting should always come first, and this can happen in two ways. The first – slow composting – is a do-it-yourself technique that is explained in the Humanure Handbook, an online practical guide by Joseph Jenkins (who coined the term ‘humanure’). Slow composting happens at low temperatures and takes about one year in a moderate climate. To be secure, most say the resulting (odourless) compost should only be used for growing crops where there is no direct contact between food and fertilizer (like fruit trees) and for inedible plants (flowers, houseplants).

The second method is composting at high temperatures, which goes much faster and results in a fertilizer that can be applied to any kind of food crop. It is an industrial process, which is being applied successfully in several countries for a number of years. Interestingly, the first step of this process also generates electricity, further improving the sustainability of the whole system. Since 2005, a factory of the Dutch company Orgaworld composts diapers (from babies and elderly) together with many other kinds of organic waste. It is a high-tech process that takes about 6 weeks and results in a high-quality compost, free from pathogens, medicines and hormones. The company has also built two factories in Canada and is building plants in the UK.

Can We Feed the World Using Humanure?

Can we produce enough natural fertilizer to substitute for synthetic nitrogen and mined potassium and phosphates? According to the figures collected by F. H. King, an adult person produces on average 1,135 grams of dung and urine each day. How much nitrogen, potassium and phosphates does this contain? That all depends on the diet. From the China of 100 years ago, King cites different research results, ranging from 2.9 to 6 kilogram (5.8 to 12 pounds) of nitrogen per person per year, 0.9 to 2 kilogram (1.8 to 4 pounds) of potassium per person per year, and 0.4 to 1.5 kilogram (0.8 to 3 pounds) of phosphates per person per year.

At present, the world population is estimated at 6,800,000,000 people. Let’s assume they all have a similar diet as the early 20th century Chinese and that the highest figures given by King more closely resemble today’s diets (reliable present-day figures are hard to find). This would mean that the total world population could produce 40.8 million tonnes of nitrogen, 14 million tonnes of potassium and 10.4 million of phosphates. Is that enough to eliminate the need for artificial fertilizers? At first sight, no. Today’s artificial fertilizer production is:

• 99.9 million tonnes of nitrogen, or more than double the amount that all people could possibly produce (40.8 million tonnes)

• 37 million tonnes of phosphates, almost 4 times the amount that all people could produce (14 million tonnes)

• 25.8 million tonnes of potassium, or more than 1.8 times the amount that all people could produce (10.4 million tonnes)

The Labours of Hercules

However, we humans have “outsourced” a considerable amount of dung production to farm animals. A large amount of artificial fertilizer is used to produce livestock feed. These animals produce much more manure than all the people on the planet. Livestock excreta in 2004 were estimated to contain 125 million tonnes of nitrogen and 58 million tonnes of phosphates (there are no figures for potassium, which we will further ignore). That’s 3 times more nitrogen and 6 times more phosphates than can be found in humanure. Animals played a minor role in the Chinese humanure-based agricultural economy, but the European farmers in the Middle Ages relied heavily upon livestock for manure, which was their main fertilizer. Animal manure was never wasted. Joseph Needham cites Fussell:

European farmers of the 15th to 17th centuries, both high and low, had one main worry, manure. They dared not neglect any source of supply, however minute, for the success of every crop they grew depended largely on the amount they could accumulate for use. They were willing to undertake the labours of Hercules to build a sufficient dunghill.

There are many good reasons to cut back on meat consumption, both for our health and for the environment – livestock production is also the main driver of deforestation (in its turn a major driver of soil degradation). However, if we don’t want to give up our high meat consumption, the least we should do is “to undertake the labours of Hercules to build a sufficient dunghill”. It would not only save us the effort to produce an ever increasing amount of artificial fertilizers, but it would also stop the devastating ecological consequences of dumping 91 million tonnes of nitrogen and 49 million tonnes of phosphates into the environment every year. Most of this is discharged without any treatment, illegally, or legally by overdosing it on fields near cities as a cost-effective waste management practice.

Food Scraps & Management Techniques

There is another source of natural fertilizer material that is being wasted – food scraps. In this case, too, we turn a valuable resource into a waste product. Food scraps could be fed to animals like pigs, greatly improving the sustainability of meat production. But, instead, we feed them grain. Of all the food scraps produced in the US, only 3 percent is currently being recycled. The rest ends up in landfills, producing large amounts of greenhouse gases. There is also a large potential to lower demand – one of the main problems with today’s fertilizer use is overconsumption. Artificial fertilizers are cheap and as a result farmers prefer to dose their crops with too much fertilizer, instead of risking not using enough and lowering their yields. This means that more nutrients are lost through soil erosion, runoff and leaching – which also pollutes groundwater, rivers and seas, because these nutrients do not pass through sewage stations.

Things were very different in the early Chinese agricultural system and during the European Middle Ages. There was never a surplus of fertilizer, so farmers applied it thoughtfully. With more careful techniques, today’s farmers could get the same yields with the use of much less fertilizer. The use of crop rotation, intercropping and green manure, all historically important techniques which are still being applied in today’s organic agriculture, could further reduce the demand for fertilizers.

Nutrient Balance

Let’s digest all this information for a second. On the one hand, we have livestock and people, who together produce 166 million tonnes of nitrogen and 72 million tonnes of phosphates. Almost all of this is wasted, wreaking ecological havoc. At the same time, our factories produce 99.9 million tonnes of artificial nitrogen fertilizer and 37 million tonnes of phosphates. A completely superfluous operation that further increases pollution and consumes vast amounts of energy. With the expected human (and livestock) population growth, both biological and artificial production will rise even further, making everything only worse.

We have more than likely already passed the stage where humanity could be sustained without inorganic fertilizers. It is, after all, artificial fertilizers that caused the population boom of the 20th century. However, this should not be a problem. The large amounts of human and animal dung include nutrients which originate from inorganic fertilizers, since we all eat food that is largely grown by means of inorganic fertilizers. It is estimated that humans have already doubled the amount of nutrients in the global ecosystem. Thus, the main problem is not that we produce inorganic fertilizers it’s that we don’t recycle them.

Logistic Challenge

Even if we only consider livestock manure, there is enough natural fertilizer available to sustain almost 7 billion people. There is also no taboo when it comes to utilising animal manure, so why don’t we use it? Nutrients recovered as animal manure and applied to agricultural lands were estimated globally at a mere 34 million tonnes of nitrogen (28 percent of total) and 8.8 million tonnes of phosphates (15 percent) in 1996. The amount wasted thus equals (for nitrogen) or surpasses (for phosphates) artificial fertilizer production. This is the consequence of an industrial and intensive meat and dairy production system that is operating on a global scale. In many countries cattle eats fodder that is produced on the other side of the world. So, in order to close the loop, we would have to ship the manure back to where the fodder comes from. The FAO writes:

Even if livestock is raised on the same continent as where its feed is grown, the scale and geographical concentration of industrial feedstock production causes gross imbalances that hamper manure recycling options. High labour and transport costs often limit the use of manure as organic fertilizer to the direct vicinity of the production facilities.

Of course, the same can be said of human manure. Just like livestock, humans are geographically concentrated in large cities with no farmland in sight. Just like livestock, we eat food that is often produced far away from where we live. This means that if we choose to collect humanure, we have to ship it back from the place of food consumption to the place of food production. Consequently, recycling nutrient elements would bring along a massive logistic system consisting of trucks, trains and ships transporting dung (or pipelines transporting sewage) all over the world.

We are not saying that every ounce of dung should be sent back to the place where the food was grown; this is impossible and ridiculous. What counts is that there is a balance between import and export of nutrients. Countries that export food should also choose to import (other) food, instead of dung, yielding the same result and increasing the dietary variety. All we would essentially need is a sophisticated nutrient accounting system.

The fundamental solution, of course, is to produce food more locally. This would not only do away with the shipping of manure, but also with the shipping of food. If livestock production would be geographically more diversified and mixed with cropland, all the animal manure could be used and artificial fertilizers would not be needed. If cities were smaller and distributed more uniformly throughout farming country, the logistics of returning humanure to farmland would be greatly simplified. Of course, this ‘decentralisation’ of the human population goes against the notion that densely populated cities are more sustainable than a more uniformly distributed population. The challenge may not be to abandon Suburbia, but to make it more self-sufficient.

Many thanks to Sietz Leeflang, inventor of the Nonolet composting toilet, who spent two years trying to convince me to write this epos on shit, and who referred me to most documents listed in the references. ←

Illustration by Diego Marmolejo.

Humanure transport in China.

Shanghai traded and distributed the yield of its inhabitants over a specially designed canal network using hundreds of boats.

Night soil collection in Amsterdam, the Netherlands.

Night soil collection in Amsterdam, the Netherlands.

Charles Liernur’s vacuum toilet.

References

King, F. H. (1911). Farmers of forty centuries: Permanent agriculture in China, Korea and Japan = Si qian nian de nong fu : Zhongguo, Chaoxian he Riben de yong jiu xing nong ye. Guilin: Guangxi Normal University Press. (Dung recycling in china, korea and japan)

Needham, Joseph (1984). Science and civilisation
in China. Vol. 6: Biology and biological technology. Cambridge: Cambridge University Press.

Lintsen, H. W. (red.) (1993). Geschiedenis van de techniek in Nederland. De wording van een moderne samenleving 1800-1890. Deel II. Gezondheid en openbare hygiëne. Waterstaat en infrastructuur. Papier, druk en communicatie. Walburg Pers, Zutphen.

Brown, A. Duncan (2003). Feed or feedback: agriculture, population dynamics and the state of the planet. Utrecht: International Books. (The nutrient cycle and how to restore it … great book!)

The history of sanitary sewers (website, s.d.). http://www.sewerhistory.org/. (The Liernur system and other early sewer systems)

Gray, Samuel M. (1884). Proposed Plan for a Sewerage System, and for the Disposal of the Sewage of the City of Providence. Providence: Providence Press Company, Printers to the City. (Accessible through “The history of sanitary sewers” website; the technical options at the end of the 19th century.)

Jenkins, Joseph (2005). Humanure Handbook a guide to composting human manure. Grove City, Pa: Jenkins Publications. (DIY)

Philpott, Tom (2010) “The nitrogen dilemma: is America fertilizing disaster?” Grist Magazine, http://www.grist.org/article/series/the-n2-dilemma-is-america-fertilizing-disaster. (Inorganic fertilizers)

Steinfeld, Henning & Gerber, Pierre J. & Wassenaar, Tom & Castel, Vincent & Rosales, Mauricio & De haan, Cornelis (2006). Livestock’s Long Shadow: Environmental Issues and Options. United Nations Food and Agriculture Organization

Armstrong, Donald L. (Editor) (1998). “Production and use of potassium” in Better Crops With Plant Food. A Publication of the International Plant Nutrition Institute (IPNI) LXXXII (82), No. 3, pp. 6-7. Accessible through http://www.ipni.net/publication/bettercrops.nsf/0/E90E04A957EA624285257980007CD63C/$FILE/BC-1998-3.pdf

Roberts, T. L. & Stewart, W. M. (2002). “Inorganic phosphorus and potassium production and reserves” in Better Crops With Plant Food. A Publication of the International Plant Nutrition Institute (IPNI) LXXXVI (86), No. 2, pp. 6-7. Accessible through http://www.ipni.net/publication/bettercrops.nsf/0/BC60B280CF5ACEBB85257980007AA468/$FILE/Better%20Crops%202002-2%20(lo%20res).pdf

UNEP (2001). Environmental aspects of phosphate and potash mining. Paris: UNEP & IFA. Accessible through https://web.archive.org/web/20130709045747/http://www.elaw.org/system/files/PotashMining.pdf

Elser James & White Stuart (2010). “Peak Phosphorus”, Foreign Policy (online magazine). Accessible through http://www.foreignpolicy.com/articles/2010/04/20/peak_phosphorus

Lewis Leo (2008) “Scientists warn of lack of vita phosphorus as biofuels raise demand”, Times Online. Accessible through https://www.thetimes.co.uk/article/scientists-warn-of-lack-of-vital-phosphorus-as-biofuels-raise-demand-q7bnz5d665g

Pinto Ferdinand M. (1583), The voyages and adventures of Ferdinand Mendez Pinto, a Portugal: During his travels for the space of one and twenty years in the Kingdoms of Ethiopia, China, Tartaria, …(English translation by H. C. Gent, published in London: F. Macock, 1663).

The Status Quo of Electric Cars: Better Batteries, Same Range

We don’t need better batteries, we need better cars.

Electric motors and batteries have improved substantially over the past one hundred years, but today’s much hyped electric cars have a range that is – at best – comparable to that of their predecessors at the beginning of the 20th century. Weight, comfort, speed and performance have eaten up any real progress. We don’t need better batteries, we need better cars.

The Forgotten History of the Electric Vehicle

From about 1895 to the mid-1920s, and following the bicycle craze of the 1890s, electric cars shared the road with petrol and steam powered cars. Electric vehicles (EV’s) were comparatively slow, heavy, and had a smaller range than their alternatives. During the very early years, however, electric automobiles were the most popular option for a short time, mainly because of two reasons. Firstly, they were easy to start, while a gasoline car had to be cranked up and a steam powered car required a long firing-up time. Secondly, there were few paved roads outside the city at the turn of the 20th century, which made the limited range of EV’s not that problematic. The production peaked in 1912: during that time there were 30,000 EV’s on the road in the United States, two-thirds of these were used as private passenger cars. Europe had around 4,000 electric vehicles.

By 1912, the gasoline car had already taken over the largest share of the automobile sales (more than 90 percent). They were faster and could drive longer distances – not only because of their better range but also because of a more elaborate refuelling infrastructure. The rapidly expanding paved road network worked in their favour, too. Internal combustion engines became much cheaper than electrics. In 1908, Ford introduced its mass-produced (and gasoline powered) Model-T, which initially sold for $ 850 – two to three times less than the price of a similar electric vehicle. In 1912, the price of the Model-T came down to $ 650. That same year, the electrical starter for gasoline vehicles appeared, and took away one of the last selling points of EV’s. Last but not least, gasoline had become much cheaper than it had been at the end of the 19th century.

The only advantage left was the (relative) cleanliness and noiselessness of electric vehicles, the reason we want them back today. In 1914, Henry Ford announced the marketing of a cheap mass-produced electric vehicle, but this automobile was never produced. In Europe, electric passenger cars were gone in 1920, in the US they survived for a decade longer. Electric trucks, outside the scope of this article, remained successful for a longer period. The manufacturers of early electric cars made several strategic mistakes. For instance, it took them until 1910 to develop a standard for the charging of the batteries. But, at the heart of the failure of the early electric car lay the limited capacity of the storage battery.

Then and Now: 100 Miles

If today’s supporters of EV’s would dig into the specifications and the sales brochures of early 20th century electric horseless carriages, their enthusiasm would quickly disappear. Fast-charged batteries (to 80% capacity in 10 minutes), automated battery swapping stations, public charging poles, load balancing, in-wheel motors, regenerative braking: it was all there in the late 1800s or the early 1900s. It did not help. Most surprisingly, however, is the seemingly non-existent progress of battery technology.

The Nissan Leaf and the Mitsubishi i-MiEV, two electric cars to be introduced on the market in 2010, have exactly the same range as the 1908 Fritchle Model A Victoria: 100 miles (160 kilometres) on a single charge. The 100-mile Fritchle was a progressive engineering feat for its time, but it was not the only early electric that boasted a 100 mile range. I have only chosen it because its specifications are most complete, and because its range was certified.

The first electric cars (1894-1900) had a range of 20 to 40 miles (32 to 64 kilometres), still better than the 20 km “range” of a horse. The average second generation EV (1901-1910) already boasted a mileage of 50 to 80 miles (80 to 130 km). The third generation of early electric cars (1911-1920), including larger vehicles that could seat 5 people comfortably, could travel 75 to more than 100 miles (120 to more than 160 km) on a single charge – and this is still the range of electric cars today.

100 Miles = Upper Limit

In fact, the range of the Nissan Leaf or the Mitsubishi i-MiEV may be far worse than that of the 1908 Fritchle. The range of the latter was (officially) recorded during an 1800 mile (2,900 km) race over a period of 21 driving days in the winter of 1908. The stock vehicle was driven in varied weather, terrain and road conditions (often bad and muddy roads). The average range on a single charge was 90 miles, the maximum range recorded was 108 miles. [1][2]

The range of the Mitsibushi i-MiEV and the Nissan Leaf was tested in a very different manner. On rollers instead of on actual roads, and in a protected environment, but that’s not all. Both manufacturers advertise the US EPA city range, a test that supposes a 22 minutes drive cycle at an average speed of 19.59 mph (31.5 km/h), including one acceleration to 40 mph (64 km/h) during no more than 100 seconds.

Critics blame today’s manufacturers for not displaying the EPA combined cycle range, which also includes trips on the motorway (the EPA highway cycle). Contrary to vehicles with an internal combustion engine, electric cars are more fuel efficient in cities than at steady speed on a highway – an electric motor uses no energy when it is idling, and regenerative braking works best in city traffic. Darryl Siry, former CMO of Tesla, estimates that the correct range of the Nissan (and other modern electric cars) will be around 70% of the advertised range. That would bring the range of today’s electrics to the same level as the 1901 Krieger Electrolette (68 miles).

Even the EPA combined cycle figures should be considered as an upper limit. Firstly, with an average speed of 48 mph (77 km/h) the highway tests are outdated. Secondly, the range of a car is also affected by other factors: not only excessive speeding and fast accelerations, but also the use of headlights at night, the use of heating or air-conditioning, the use of other options onboard, driving over hilly roads or in headwinds – or all of these factors combined (the EPA has added new test cycles in 2008 to address these points, but the results are not yet available for the EV’s we are talking about).

Some of these factors not only concern today’s electrics, but also those of yesteryear. However, the Fritchle’s range was tested on varied terrain and in varied weather conditions, which was not the case for the Nissan or the Mitsubishi. Moreover, early electrics had no air-conditioning and few had heating systems – drivers and passengers dressed warm in winter. Mitsubishi warns its clients that the use of the heater might cut the range in half. All in all, the range of a 2010 electric vehicle will be closer to 50 miles (80 km) than to 100 miles (160 km). And that’s to be expected from a battery at the beginning of its life – after 5 years, the capacity will be at least 20 percent less.

Better Batteries

In spite of this, the 2010 vehicle has a much better battery under the hood than the 1908 vehicle. The Fritchle Electric had lead-acid batteries, like all its contemporaries, with an energy density between 20 and 40 Wh/kg (early 1900 batteries had energy densities of only 10 to 15 Wh/kg). The Nissan and the Mitsubishi have a more powerful lithium-ion battery with an energy density of around 140 Wh/kg.

The Nissan’s battery can thus store 3.5 to 7 times more energy for a given weight than an average early electric from about 1910. This could have resulted in a vehicle with a 3.5 to 7 times better range (350 to 700 miles or 560 to 1,130 km), but this is not the case. The technological improvements could also have been translated into a 3.5 to 7 times lighter (and smaller) battery, and consequently a lighter and more fuel efficient vehicle, but this is not the case either.

The battery of the Nissan Leaf is only 1.6 times lighter than the battery of the Fritchle: 220 kg (480 pounds) versus 360 kg (800 pounds). The Nissan vehicle (including the battery) weighs more than the Fritchle: 1,271 kg (2,800 pounds) versus 950 kg (2,100 pounds).

Motor Output, Speed & Acceleration

The most obvious difference between the specifications of the old and new cars is the power of their motors. The 1908 car had a 10 HP motor, the 2010 car has a 110 HP motor. In other words, the Nissan Leaf has the motor output of 11 electric Fritchles. The smaller and lighter Mitsubishi i-MiEV (1,080 kg or 2,400 pounds) has the motor power of 6.5 electric Fritchles.

The maximum speed of the Fritchle was 40 km/h (25 mph), the Nissan does 140 km/h (87 mph) and the i-MiEV is not far behind (130 km/h or 81 mph). Acceleration data cannot be compared, but there is no doubt that the 2010 cars will accelerate many times faster (and can climb hills much more easily) than their early 1900 cousins. Today, fast acceleration times are one of the selling points of EV’s. The risks of more powerful electric motors were already recognized in the early 1900s. The Hawkins Electrical guide (1914) states:

Very quick acceleration is an objectionable feature in electric vehicle design, because a vehicle constructed with this feature puts a heavy overdraft on the battery.

A few years earlier, members of the Electric Vehicle Association of America tried to impose a standard maximum speed of 32 km/h (20 mph) for electric vehicles, because power requirements increased rapidly above that limit. They feared that higher speeds would threaten the all-important range of the automobiles. They did not succeed. Too many manufacturers tried to compete with gasoline cars (and with each other) by designing faster electric vehicles.

Fuel use increases faster than speed, so it seems clear that velocity is the reason why the range of today’s electric cars did not improve in spite of better batteries. However, it’s more complicated than that. The EPA city range that the modern EV’s advertise, is based on an average speed of 20 mph or 31 km/h – below the 25 mph top speed of the Fritchle, and almost exactly the same as the speed at which the vehicle could drive 100 miles on one charge. While high speeds are definitely a significant factor when considering the real world range of today’s electric cars, it cannot explain the disappointing “official” range. Faster acceleration might play a role, but the EPA-tests described above do not consider aggressive driving either so there must be other factors at play.

Oversized Cars & Motors

The first is weight. While the battery of the Nissan is lighter than the battery of the Fritchle, the Nissan vehicle including the battery is 321 kg (706 pounds) heavier. Without the battery, the Nissan weighs almost twice as much as the Fritchle: 1,051 kg (2,310 pounds) versus 590 kg (1,300 pounds). So while batteries became more than 3 times lighter in 100 years time, the weight of the vehicle itself (without battery) doubled. The extra weight of the Nissan already nullifies a significant portion of the progress: a 35 percent higher mass can lead to a 28 percent reduction in range. [3] [4]

The second factor is directly related to the massive increase in horse power. Electric motors are (generally) most efficient around 75 percent of their rated load. Their efficiency drops dramatically below 25 percent. The Fritchle was most efficient at a speed of around 20 mph. The much more powerful motor of the Nissan Leaf, however, is most efficient at a speed of around 105 km/h, far above the average speed in the tests. Today’s EV’s consume less energy at low speeds than at high speeds because of other factors, but compared to early electrics with their much less powerful motor they are probably less efficient at speeds of around 20 mph. [5]

Computers on Wheels

The third factor is the electronics. Modern cars have, depending on the model, 30 to 100 microprocessor-based electronic control units onboard. [6] These computers add weight but also consume energy in a direct way. Part of this direct energy consumption is not included in the EPA-tests – electronically adjustable windows and mirrors, for example.

However, many other electronics are activated whenever the vehicle is driving. Examples are power brakes, active suspension, safety sensors, dashboard instrumentation and the management of the battery itself (not required for a lead-acid battery but critical for lithium-ion storage technology). All this electrical energy has to be supplied by the battery.

While a higher performance cannot explain the relatively low official range of today’s EV’s, all factors described above are at least partially a consequence of it. Lower speeds would make most safety-related electronics unnecessary and they would do away with the need for larger motors and batteries which, just like the electronics, add more weight.

Tesla Roadster

Some of you might wonder why I don’t compare the 1908 Fritchle to the 2008 Tesla Roadster. This car has a range of 244 miles (393 kilometres), 2.44 times better than the old timer and the modern Japanese cars – and this according to the EPA combined cycle, not the EPA city figures (Although the EPA-combined range advertised by Tesla is of course as much suited for a sports car as the EPA-city range is suited for a family vehicle like the Nissan Leaf).

The Tesla Roadster is less progressive than it seems, though. The battery of the sports car weighs twice as much (450 kg) as the battery of the Nissan (220 kg). Since both batteries have a similar energy density, you don’t have to be a rocket scientist to calculate that the heavier battery has about twice the capacity: 53 kWh to be exact, compared to 24 kWh for the Nissan’s battery (and 16 kWh for the i-MiEV). Considering the fact that both cars have a similar weight, a 2.5 better range for a battery with more than double (2.2 times) the capacity is far from a revolutionary engineering feat.

Embodied Energy of EV Batteries

Doubling battery capacity is one way to increase the range of an electric vehicle (see also the Mini E, which sacrifices its rear seat for a larger battery and gets 104 miles), but this option is far from sustainable since it also doubles the amount of energy needed to manufacture the battery. It also doubles the costs, of course. The battery of the $ 109,000 Tesla Roadster sells for $ 30,000, as much as an entire Nissan or Mitsubishi vehicle.

Nobody has investigated how much energy it takes to produce a Tesla Roadster battery, or any other EV battery for that matter, but you can get an idea of it using an online tool from Carnegie Mellon University. Corresponding to these data, $ 30,000 of economic activity in the storage battery sector (including the production of li-ion batteries) equals an energy consumption of 23,222 kWh – that’s almost 6 years of electricity consumption by an average British household. The battery has to be replaced after a maximum of 7 years.

These figures suggest that the embodied energy of the battery – not considered in any research paper that investigates the ecological advantages of electric cars – makes up for a substantial amount of the total energy cost of an electric automobile. At the advertised energy use of 21 kWh per 100 miles, 23,222 kWh would take the Tesla 109,938 miles (176,929 km) far. That’s almost 30,000 km (18,600 miles) per year, or 80 km (51 miles) per day. The low “fuel” costs are only half the story if the “fuel tank” itself is that energy-intensive.

Miracle Battery

Today, just like 100 years ago, EV proponents are divided on the question of how to market electric vehicles. Some keep emphasizing the fact that most people never drive further than 30 miles per day – therefore the current batteries are well suited to perform their task. Most cars will be charged overnight, battery-swapping stations and fast-charging will do the rest.

Others, however, keep hoping for a revolutionary storage technology that will eventually give EV’s a similar range to that of gasoline cars. This belief is supported by press releases like this: “Nanowire battery can hold 10 times the charge of lithium-ion”. It is interesting to note that the arrival of such a miracle battery has been “just around the corner” for over 100 years now. The following quotes are from 1901:

A large number of people interested in stored power are looking forward to a revolution in the generating power of storage batteries, and it is the opinion of many that the long-looked-for, light weight, high capacity battery will soon be discovered [7].

The demand for a proper automobile storage battery is so crying that it soon must result in the appearance of the desired accumulator. Everywhere in the history of industrial progress, invention has followed close in the wake of necessity [8].

Edison himself promised a radical improvement to the lead-acid battery at the turn of the 20th century. It took almost a decade before the Edison battery appeared on the market, and even though it had some advantages over the others, it was very expensive (the price of a gasoline powered Ford Model-T) and far from revolutionary. The promise of a miracle storage technology reared its head again in the 1960s and 1970s, when electric cars went through a short revival:

The consensus among EV proponents and major battery manufacturers is that a high-energy, high power-density battery – a true breakthrough in electrochemistry – could be accomplished in just 5 years [9].

The range of most electric (concept) cars in the 1960s and 1970s was considerably lower than that of early 1900 electrics. This was because they were still making use of similar lead-acid batteries, while the cars themselves were already much heavier and more powerful.

Realistic Electric Vehicles, Scenario 1

The miracle battery might one day arrive, but history teaches us not to count on it. What would definitely yield results, on the other hand, is to use existing technology and downsize the car. There are two ways to do this, as was briefly noted above. The first is to go back to early 20th century electric vehicles and equip them with modern batteries. This would extend their range spectacularly, as much as a (not yet existing) nanowire battery could.

If you were to put the lithium-ion battery of the Nissan Leaf in the 1908 Fritchle, the vehicle would have a range of about 644 km (400 miles). If you put a lithium-ion battery with the same weight of the Fritchle-battery inside, you get about 700 miles (1,127 km) range. Add to this the fact that we now also have lighter and more efficient motors (and other vehicle parts) and the range will become even greater.

Even with the headlights and the heating on, driving home over windy hills and muddy roads, such a car would give a safe and comfortable range, similar to that of today’s gasoline vehicles. Moreover, it would consume less energy: the Fritchle used around 7 kWh/100 km, the Nissan Leaf at least 15 kWh/100 km.

A better range is much more than a convenience for the driver. It would also mean that we need fewer charging and battery swapping stations, which would greatly lower the costs and the embodied energy of the required infrastructure. In short, slower vehicles would make EV’s a whole lot more likely. Interestingly, we don’t even have to streamline them. Early electrics had style, and at low speeds aerodynamics is not an important factor in energy consumption.

Realistic Electric Vehicles, Scenario 2

Of course, slow vehicles with the appearance of a horse carriage will not appeal to everybody. But there is another way. We could also downsize the electric car by designing much lighter and fuel efficient vehicles. This is shown by a concept EV like the Trev. This vehicle’s performance is comparable to that of the Nissan Leaf or the Mitsubishi i-MiEV: it has a top speed of 120 km/h (74.5 mph) and it accelerates from 0 to 100 km/h (60 mph) in less than 10 seconds.

However, its battery is almost five times lighter (45 kg or 99 pounds) and the vehicle itself (including the battery) weighs only 300 kg (660 pounds). In spite of its higher performance, it consumes as much energy as the Fritchle: 6.2 kWh/100 km, half the fuel consumption of the Nissan. Yet, the range of the Trev is similar to that of the Nissan or the Fritchle: 150 km or 93 miles. The reason is of course that if you design a much lighter vehicle, it will also have a much smaller battery that consequently holds less energy. With gasoline powered automobiles, the potential of weight reduction is much larger.

Nevertheless, a vehicle like the Trev would have almost as much benefits as a Fritchle with a 2010 battery. It would still require an elaborate charging infrastructure, but because of its much smaller battery it would seriously relieve the problem of peak demand: fast-charging could become a realistic option without the need to build hundreds of new power plants. It would also have the substantial advantage of holding a battery that is much less energy-intensive to produce.

We Cannot Have It All

Of course, there are many more possibilities than the two scenarios outlined here. It would not kill us to drive at speeds of 20 mph, on the contrary, but there is so much potential in downsizing the automobile that we don’t have to go all the way back to the early 1900s to get a decent range. We could tune them up a bit so that they could get 60 km/h or 40 mph and accelerate just fast enough to leave a crime scene or flee from a mad elephant.

At 60 km/h or 40 mph a trip of 600 kilometres or 400 miles would take 10 hours, instead of 5 hours at a common motorway speed. This does not sound like the end of the world. It’s definitely a whole lot faster than going by foot (120 hours) or by bike (30 hours). We could also equip the Trev with a somewhat larger battery so that it gets a better mileage at the expense of a somewhat lower speed. Or, yet another possibility: keep the Trev like it is but limit its speed to that of the Fritchle.

If we want more speed, we have to sacrifice range. If we want more range, we have to sacrifice speed. If we want to keep the (energy) costs of the charging infrastructure within reasonable limits, we have to sacrifice speed or size. The lesson to be learned here, is that we cannot have it all: range, speed and size. And yet, that’s what we are trying to do. ←

The 1908 Fritchle electric had a range of 100 miles (160 km).

Electric vehicles from the early twentieth century. Horseless vehicles, automobiles, motor cycles operated by steam, hydro-carbon, electric and pneumatic motors. Hiscox, Gardner Dexter, 1900.

Electric vehicles. An illustrated directory of the specifications of all domestic and foreign motor-cars and motor business wagons gasoline, steam, and electric sold in this country, New York, 1907.

Charging an electric car in 1909.

The 15 HP Babcock Electric Roadster (1911) had a range of 100 miles when driven at 17 mph (27 km/h). Its top speed was 30 mph (48 km/h).

References

Hiscox, Gardner Dexter (1901). Horseless vehicles; automobiles, motor cycles operated by steam, hydro-carbon, electric and pneumatic motors; a practical treatise for ... everyone interested in the development, use and care of the automobile, including a special chapter on how to build an electric cab, with detail drawings. New York: N. W. Henley & co.

An Illustrated Directory of the Specifications of All Domestic and Foreign Motor-Cars and Motor Business Wagons Gasoline, Steam and Electric Sold in This Country 1907. (1907). New-York: S.W. Green.

Kirsch, David A. (2000). The Electric Vehicle and the Burden of History. New Brunswick, NJ: Rutgers University Press.

Mom, Gijs (2004). The Electric Vehicle:
Technology and Expectations in the Automobile Age. Baltimore : Johns Hopkins University Press.

Boursin, Philippe. Histoire de la voiture électrique. (website, s.d.) Accessible through https://web.archive.org/web/20101212030015/http://philippe.boursin.perso.sfr.fr/velec/velec.htm.

Wallis-Tayler, Alexander J. (1897). Motor cars; or, power carriages for common roads. London: Crosby Lockwood & son, pp. 155-170.

Servonnet, Hyacinthe & Rolley, Paul (1940-1941) “Court histoire de l’automobile électrique routière”, Bulletin de la Société d’Encouragement pour l’Industrie Nationale, Paris, pp. 185-191.

Graham, Frank D. (1914). “Chapter LXXVII: Electric Vehicles” in Hawkins, Nehemiah (1914). Hawkins Electric Guide: questions, answers & illustrations, vol. 9. New York: Theo. Audel & Co, pp. 2815-2854.

H., L. (1901). “Salon de l’Automobile: les petites voitures”, La Nature, Paris: Masson, pp. 183-186.

Wallis-Tayler, Alexander J. (1905). Motor vehicles for business purposes; a practical handbook for those interested in the transport of passengers and goods. London, C. Lockwood and son.

Ladurant, P. (1901). “Les voitures Electricia”, La Nature, Paris: Masson, pp. 39-41.

Anderson, Curtis D. & Judy (2005). Electric and Hybrid Cars: A History. Jefferson, NC: McFarland & Company.

Beavan, Arthur (1903). Tube, train, tram, and car; or up-to-date locomotion. London: G. Routledge & sons.

Allen, Jonathan (1975). “Alternatives to the gasoline automobile”, The Steam Automobile, Vol. 17, No. 1.

[1]: Sulzberger, Carl (2007). “100 Miles On One Charge: The remarkable Fritchle electric car”, IEEE Power Engineering Society. Accessible through https://web.archive.org/web/20080410213307/http://www.ieee.org/organizations/pes/public/2006/nov/peshistory.html.

[2]: Wikipedia, The Free Encyclopedia, s. v. “Oliver Parker Fritchle”, https://en.wikipedia.org/wiki/Oliver_Parker_Fritchle.

[3]:World Auto Steel (2010). “Mass Reduction and Fuel Efficiency”. Accessible through https://web.archive.org/web/20100710073033/http://www.worldautosteel.org/WhySteel/Mass-Reduction/Fuel-Efficiency.aspx.

[4]: Wohlecker, R., Johannaber, M., and Espig, M. (2007). “Determination of Weight Elasticity of Fuel Economy for ICE, Hybrid and Fuel Cell Vehicles”, SAE Technical Paper, April 16, 2007.

[5]: “Determining electric motor load and efficiency” factsheet, Motor Challenge, U.S. Department of Energy. Accessible through https://web.archive.org/web/20080317155700/http://www.p2pays.org/ref/40/39569.pdf.

[6]: Charette, Robert N. (2009). “This Car Runs on Code”, IEEE Spectrum, February 1, 2009.

[7]: Hiscox, Gardner D. (1901). Horseless Vehicles, Automobiles, Motor Cycles Operated by Steam, Hydro-carbon, Electric and … New York: Norman W. Henley & Co.

[8]: Electrical Review (1901).

[9]: Machine Design (1974).

The Sky is the Limit: Human-Powered Cranes and Lifting Devices

The only advantage that fossil-fuelled powered cranes have brought us, is a higher lifting speed.

From the earliest civilisations right up to the start of the Industrial Revolution, humans used sheer muscle power, organisation skills and ingenious mechanics to lift weights that would be impossible to handle by most power cranes in operation today.

5,000 Years of Construction

The most common tower crane used in construction today has a lifting capacity of some 12 to 20 tonnes. For quite a few construction projects in ancient history, this type of crane would be completely inadequate. The majority of stones that make up the almost 140 discovered Egyptian pyramids have a weight of “only” 2 to 3 tonnes each, but all of these structures (built between 2750 and 1500 BC) also hold stone blocks weighing 50 tonnes, sometimes more. The temple of Amon-Ra at Karnak contains a labyrinth of 134 columns, standing 23 metres (75 feet) tall and supporting crossbeams weighing 60 to 70 tonnes each.

The 18 capital blocks of Trajan’s column in Rome weigh more than 53 tonnes and they were lifted to a height of 34 metres (111 feet). The Roman Jupiter temple in Baalbek contains stone blocks weighing over 100 tonnes, raised to a height of 19 metres (62 feet). Occasionally, our forebears lifted even heavier stones. The gravestone of Theoderic the Great in Ravenna (around 520 AD) is a 275 tonne stone block that was lifted to a height of 10 metres. The temple dedicated to Pharaoh Khafre in Egypt is made up of monolithic blocks weighing up to 425 tonnes.

The largest Egyptian obelisk weighed more than 500 tons and stands more than 30 metres tall, while the largest obelisk in the Kingdom of Axum in Ethiopia (4th century AD), raised up to a similar height, weighed 520 tonnes. The Colossi of Memnon, two statues of 700 tonnes each, were erected to a height of 18 metres and the walls in the Roman Baalbek temple complex (1st century BC) contain almost 30 monoliths weighing 300 to 750 tons each. Only the most powerful contemporary cranes could handle stones of this weight.

Raising construction materials to impressive heights seemed to be no problem either. The Alexandria lighthouse (3rd century BC) stood more than 76 metres (250 feet) tall. The Egyptian pyramids rise up to 147 metres. During the Middle Ages some 80 large cathedrals and around 500 large churches were built with a height of up to 160 metres – out of reach for all but the most recent top model crawler cranes.

Human Lifting Power

Considering the type of cranes that would be needed today, one wonders how our forebears were able to lift such impressive weights without the help of sophisticated machinery. The fact is, they had advanced machinery at their disposal. The only difference with contemporary cranes is that these machines were powered by humans instead of fossil fuels. Basically, there is no limit to the weight that humans can lift by sheer muscle power. Nor is there a limit to the height to which this weight can be lifted. The only advantage that fossil fuelled powered cranes have brought us, is a higher lifting speed.

Of course, this does not mean that one man can lift anything to any height, or that we can lift anything to any height if we just bring enough people together. But, starting more than 5,000 years ago, engineers designed a collection of machines that greatly enhanced the lifting power of an individual or a group of people. Lifting devices were mainly used for construction projects, but (later) also for the loading and unloading of goods, for hoisting sails on ships, and for mining purposes. Initially, the lifting speed of lifting machines was extremely low, while the amount of man power required to operate them remained very high. Towards the end of the nineteenth century, however, just before steam power took over, human powered lifting devices became so elaborate that one man could lift a 15 tonne truck in no time, using only one hand.

Mechanical Advantage

Any lifting device has a certain mechanical advantage (MA), the factor by which it multiplies the input force into an output force. A lower input force must always be applied over a greater distance than the greater output force travels, and the ratio of the distances is the velocity ratio (VR). In theory, the mechanical advantage (MA) = the velocity ratio (VR), so that in a machine with a mechanical advantage of 2 to 1, the input force is half the output force but must be exerted over twice the distance. In practice, friction always reduces the ideal mechanical advantage of a machine [1].

Although some think that the Egyptians had more sophisticated lifting machinery at their disposal, most historians agree that the Egyptians made use of only the most simple lifting devices: inclined planes (ramps) and levers (the principle of a seesaw or teeter-totter). Ramps were (probably) also used to raise obelisks. By moving an object up a ramp rather than completely vertical, the amount of force required is reduced at the expense of increasing the distance it must travel. The mechanical advantage of an inclined plane equals the length divided by the height of the slope. The mechanical advantage of a lever is the distance between the fulcrum and the point where the force is applied, divided by the distance between the fulcrum and the weight to be lifted.

While the methods of the Egyptians offered a considerable mechanical advantage over simply pulling up the load vertically by means of a rope, the required man power remained very high: not only to tow or flip over the stones (it must have taken around 50 men to tow a 2.5 tonne stone block), but also to build and later remove the enormous earthen ramps. Historians estimate that the workforce to build a pyramid consisted of 20,000 to 50,000 people, sometimes more. While a structure like that could be built today in a few years time with power cranes and a small workforce, most pyramids took decades to complete.

Birth of the Crane: the Pulley

The first cranes appear in Greece from about the late 6th or early 5th century BC. The Romans, more eager to build large monuments, adopted the technology and developed it further. The earliest cranes consisted of a rope passed over a pulley. Before it found an application in the lifting of objects, the single pulley was used from the 8th or 9th century BC onwards for drawing water from wells (the shaduf). A single pulley offers no mechanical advantage in itself, but it changes the direction of pull: it is easier to pull down instead of haul up. Pushing vertically upwards with one hand generates about 150 Newton, while pushing vertically downwards with one hand generates about 250 Newton [2].

Gradually, the mechanical advantage of cranes was increased with additional technology. A major improvement from the 4th century BC and still in use today, is the compound pulley: a combination of single pulleys in a block. The mechanical advantage equals the amount of pulleys used. A crane with a triple pulley (a Trispastos) has two pulleys attached to the crane and a free pulley suspended from them. It offers a mechanical advantage of 3 to 1. A crane with five pulleys in a similar arrangement (dubbed a Pentaspostos) offers a mechanical advantage of 5 to 1.

Using a compound pulley a person can lift more than he or she is otherwise able to. If a single person pulling a rope can exert a force of 50 kg, he or she can raise (or lower) 150 kg using a Trispastos and 250 kg using a Pentaspostos. The same goes for the rope. A rope with a tensile strength of fifty kilograms can be used to lift (or lower) 150 kilograms if three pulleys are used, and 250 kilograms if five pulleys are used. The downside of the compound pulley is, again, distance and thus lifting speed. Lifting a load three metres using a Trispastos will require pulling the rope for nine metres, lifting a load three metres using a Pentaspastos will require pulling the rope for fifteen metres.

In theory, any number of pulleys can be used, but because of friction ancient systems were limited to five pulleys. If more lifting power was needed, rather than increasing the number of pulleys within each block, the Romans used two or more 3- or 5-pulley sets, with different gangs working each (a Polyspastos). Of course, every rope could also be pulled by several people at once. The power loss due to friction for Roman (and medieval) cranes is estimated to be twenty percent at most [3].

Winches and Capstans

Another improvement was the introduction of the windlass (or winch) and the capstan, which both substitute for the pulling of the rope. They were invented around the same time as the compound pulley. The only difference between the winch and the capstan is that the former has a horizontal axle and the latter has a vertical one.

Both use handspikes or levers inserted into slots on a drum to gain a mechanical advantage in circular rotation, given by the radius of the handspike to the radius of the drum or axle. The mechanical advantage of a winch is the radius of the axle to the radius of the handspikes. Therefore, an axle of five centimetres (two inches) with handspikes 30 centimetres (1 ft) long has a mechanical advantage of six to one. A person operating the winch can thus lift six times more than he or she would when just pulling a rope. However, to wind up one metre of rope the handspikes would need to be turned six metres.

Combined with the compound pulley, winches or capstans already offer impressive performance. One person operating a Pentaspostos and exerting a force of 25 or 50 kilograms at the winch described above can lift a load of 750 to 1500 kilograms (25 or 50 kg × 6 × 5 = 750 or 1500 kg), while the Egyptians needed 30 to 60 people to haul up a 1500 kilogram stone block up a ramp. Just like ropes, winches and capstans can be operated by multiple people (winches by two people, capstans by many more). Capstans can also be operated by draft animals. Four people operating a capstan with a similar mechanical advantage as the winch described above, each exerting 25 to 50 kg of power, can lift – ignoring friction – three to six tonnes (100 or 200 kg × 6 × 5 = 3000 or 6000 kg). However, in both examples, for every metre the load is raised, they will have to pull in thirty metres of rope.

Treadwheels

An even more powerful lifting aid than the winch or capstan was the treadwheel. It was first mentioned in 230 BC and it remained a very important element of cranes up until the second half of the nineteenth century. Treadwheels, which usually had a diameter of four to five metres, have a greater mechanical advantage than winches or capstans, because of the larger radius of the wheel compared to the radius of the axle. Moreover, the power generated by a person’s arm and shoulder is replaced by the greater power of a person walking (not running) within the wheel.

A treadwheel with a wheel radius of seven feet (213 cm) and a drum radius of 0.5 feet (15 cm) has a mechanical advantage of 14 to one. This concerns a treadwheel with a diameter of 456 centimetres: 2 × 213 cm radius of the wheel + 2 × 15 cm radius of the drum (diameter = 2 × radius) [3]. With a mechanical advantage of 14 to one, one person in a treadwheel operating a Pentaspastos and exerting a force of 50 kilograms could thus lift a load of 3500 kilogram or 3.5 tonnes. That’s about 70 times more than he or she could lift with a simple pulley.

Some cranes (especially the harbour cranes from the middle ages and onwards) were equipped with two treadwheels attached to the same axle, bringing the total lifting power of a human powered crane to some 7,000 kilograms or 7 tonnes. Because many treadwheels were also wide enough for two people walking side by side, a crane with two treadwheels could be powered by four people, which brings the maximum lifting power at 14 tonnes – comparable to that of a common modern tower crane. Even taking into account a loss of 20 percent due to friction, this is still 11.2 tonnes.

Of course, a mechanical advantage of fourteen to one also meant that the people had to walk 140 metres inside the wheel to lift a load to a height of ten metres. If they walk five kilometres per hour, the load would be lifted at a speed of 0.35 km/h or almost six metres per minute (the velocity of the wheel divided by the velocity of the load = radius of the wheel divided by the radius of the drum) [3].

Lifting Towers

While the lifting capacity of a ancient treadwheel crane is impressive, attentive readers will have noticed that Roman buildings contained stone blocks that were considerably heavier than that. The Romans also shipped a few dozens of obelisks from Egypt and re-erected them in their cities – the heaviest of these weighing more than 500 tonnes. How did they manage this with six or twelve ton cranes? Basically, in the same way that we handle very heavy loads, by combining multiple lifting devices.

One method was to build a gigantic lifting tower powered by multiple capstans on the ground. Although the mechanical advantage of a capstan is considerably lower than that of a treadwheel, they could be powered by much more people and so less machines would be needed. Moreover, they allowed for the auxiliary power of draft animals. The method of lifting towers is briefly mentioned by some Roman authors, but detailed information about it comes from an engineer who lived 1000 years later: Domenic Fontana, master builder of the Vatican.

In 1586, Pope Sixtus V decided that the 344 ton obelisk at the Circus Maximus had to move to the square in front of the newly built Saint Peter’s Basilica. A mere 256 metres further, but nevertheless the huge stone had to be lowered, transported, and erected again. Fontana documented the undertaking extensively in his 1589 book The movement of the Vatican obelisk. By then, lifting materials, devices and methods had hardly changed since Roman times, so we can assume that the Romans raised the same stone in a similar manner.

The job was done using a wooden construction 27.3 metres tall, ropes up to 220 metres long, 40 capstans, 800 men and 140 horses (when lowering the obelisk the workforce consisted of 907 men and 75 horses).While the whole undertaking took more than a year – including the transport of the obelisk (on rollers) and the assembly of the tower, the capstans and other lifting machinery – the stone was erected in just 13 hours and 52 minutes. As a result of this successful operation, many more obelisks were moved around Rome, one of these weighing 510 tonnes.

The spectators watching the event were ordered not to speak or make any noise under the penalty of death, and police were used to enforce the orders. Silence was crucial in maintaining communication between those monitoring the ropes and pulleys at the top of the tower and those on the ground operating the capstans. The signal to begin turning was given by a trumpet; the signal to stop was given by a bell [4].

The Reinvention of Cranes in the Middle Ages

Following the decline of the Western Roman Empire, the use of elaborate cranes in Europe largely disappeared for more than 800 years. Cranes operated by winches are again recorded from the late 12th century onwards, large treadwheel cranes only reappear in the 13th (France) and 14th (England) centuries – a bit later than windmills and waterwheels. Compared to Roman times, very little technical information was written down during the Middle Ages. Most of our historical knowledge comes from paintings and from illustrations in manuscripts.

Luckily, a few treadwheel cranes have been preserved, all of them in the attics of churches and cathedrals. Large cranes were an absolute necessity in the building of the gothic churches in the late Middle Ages, buildings that were much higher than even the tallest Roman monuments. Furthermore, the working area on these sites was rather limited compared to Roman conditions, and both factors led to a different use of cranes.

Gothic Churches and Cathedrals

Most probably, cranes were installed inside the building, initially on the ground, and moved upwards (and also sidewards) as the construction work proceeded, being dismantled and reassembled multiple times. When the church was finished, some of these cranes were left above the vaulting and below the roof where they might come in handy for repairs.

One of these treadwheel cranes, in Britain’s Canterbury Cathedral, was used for a renovation project in the 1970s. It dates from the late fifteenth century, could accommodate one to two labourers and has a diameter of 4.6 metres. Medieval illustrators sometimes depicted cranes mounted on the outside of the walls, but this was done probably because it made better paintings – the walls of gothic churches and cathedrals were generally too thin to support a heavy crane and its load.

Another well described medieval lifting device is the large treadwheel slewing crane that stood on top of the 157 metre high Cologne Cathedral in Germany for almost 450 years. It was erected in 1400 and dismantled only in 1842. The crane housed two treadwheels, was 15.7 metres high and had a 15.4 metre long jib which could traverse the entire working area – basically functioning like a modern tower crane.

Harbour Cranes

A new development in the Middle Ages was the stationary harbour crane, powered by treadwheels. It was not used by the Greeks or the Romans, possibly because they had a large enough reservoir of slave labour at their disposal. The Roman standard shipping container, the amphora, was rather small and could easily and rapidly be loaded and unloaded using a human conveyor belt and a ramp [5].

Harbour cranes first appeared in Flanders, Holland and Germany in the 13th century, and in England in the 14th century. They were more powerful than cranes used in construction, and equipped with not one but two treadwheels having a larger diameter of up to 6.5 metres. These more potent “engines” were not so much aimed at heavier loads but rather at higher lifting (and lowering) speeds. In loading and unloading goods, speed was more important than in construction, where the tempo was dictated by the slow progress of the masons and carpenters.

Dockside treadwheel cranes were frequently capped by a wooden roof to protect the mechanics and the workers from the rain. These permanent structures had much in common with windmills, and they were most probably built by the same craftsmen. Analogous to post windmills and tower windmills, there were post cranes and tower cranes: the former were wooden structures which pivoted on a central vertical axle, the latter (mostly built in Germany) were masonry towers with only the cap and the jib arm rotating.

Harbour cranes were not adopted in Southern Europe and their total number in the whole of medieval Europe was rather limited compared to the number of windmills: about one hundred large harbour cranes have been discovered [5]. Around a dozen of them are still standing. The most powerful treadwheel harbour cranes were built in the London docklands in the 1850s, having two treadwheels of up to 3 metres wide, each walked by 3 to 4 men [6]. These are not to be confused with the even wider treadwheels used in nineteenth century prisons, where the men walked on the outside of the wheel.

More Flexible Cranes

Today’s cranes can turn their jib 360 degrees (slewing) and move the load horizontally along the jib. Initially, most cranes used in medieval construction work were only capable of a vertical lift. The load could only be manipulated laterally by the crane master on the ground, using a small rope attached to the load. Dockside cranes introduced the slewing crane, of which the first evidence appears in the fourteenth century. Slewing became a common feature of construction cranes in the 1600s, which shortened work cycles considerably.

The first crane that allowed a horizontal movement of the load appeared in a 1550 book of Georgius Agricola, but a real-world version was only launched in 1666 by Frenchman Claude Perrault. A trolley was moved along the whole length of the jib by means of a complicated rope system in which two ropes were wound and unwound via a spindle attached to the trolley [7].

Let’s not forget that Greek and Roman cranes were capable of very limited horizontal movement, too, by lowering or raising the masts a bit. Moreover, the Greeks already designed a kind of slewing crane, which was a lifting device as described earlier but resting only on one mast, directed and kept in balance by extra men on the ground holding ropes. Safety mechanisms (to prevent plummeting loads and sudden reverse rotation of the treadwheel or capstan) were introduced only in the late eighteenth century.

Iron Cranes

In the nineteenth century, three important innovations appeared. The first one was the use of iron instead of wood structures and gearings, which made cranes stronger and more efficient. The first cast iron crane was constructed in 1834. That same year, the wire rope was invented, a much stronger alternative to the natural fibre rope or the metal chain. Finally, in 1851, the third game-changing innovation appeared: the steam-powered crane. With the arrival of steam power, any load could be lifted at any speed, as long as the engine was powerful enough [7].

Wire rope was soon in widespread use, but the other two innovations only caught on slowly. Wood, sometimes combined with iron, continued to be the material of choice for many cranes well into the twentieth century, especially in regions where timber was plentiful. And while more and more steam cranes appeared in the second half of the nineteenth century, hand powered cranes kept being sold and used in large amounts. A book on crane technology, published in 1904, still devoted half of its pages to manually operated cranes. Bicycle cranes were sold, too.

Logically, it was also this era that produced the most powerful muscle powered cranes ever designed: those composed of iron structures and gearworks, using wire ropes, but not yet powered by steam. The best example are the dockside cranes of William Fairbairn, patented in 1850. Fairbairn riveted together two iron plates, creating an arch-shaped jib that was far more stable and practical than the previous straight wooden or iron jibs. Fairbairn steam cranes became very well known and some of them have been preserved.

Most Powerful Hand Crane Ever

Much less known, however, is that for a short time these powerful cranes were sold as hand powered machines. Because Fairbairn described these cranes in detail in the 1860 edition of his book Useful information for engineers, we know exactly what the mechanical advantage of their gearings was.

The first hand-driven Fairbairn harbour cranes were intended to lift weights of up to 12 tons to a height of 30 feet (9 metres) above the ground, and to sweep this load round over a circle 65 feet (20 metres) in diameter. Next, a 60 ton crane was built for the new docks at Keyham, which could lift loads five times heavier up to heights of 60 feet (18 metres) and over a circle 104 feet (32 metres) in diameter. It is this colossal crane, probably the most powerful hand driven crane ever built, that is described in detail by Fairbairn:

The chain passes round 4 pulleys, two moveable and two fixed, in the end of the jib. It is then conducted down in the interior of the jib over three rollers to the barrel, which is also in the tube near the ground. On each side of the crane a strong cast iron frame is fixed for receiving the axles of the spur wheels and pinions.

Four men, each working a winch of 18 inches radius, act by two 6 inch pinions upon a wheel 5 feet 3.75 inches diameter, this in turn moves the spur wheel, 6 feet 8 inches diameter, by means of an 8 inch pinion, and on the axle of the former the chain barrel, 2 feet in diameter, is fixed.

Hence the advantage gained by the gearing will be W/P = 18 × 63.75 × 80 / 6 × 8 × 12 = 158 or taking the number of cogs in each wheel W/P = 18 × 95 × 100 / 12 × 9 × 10 = 158 and as this result is quadrupled by the fixed and moveable pulleys, the power of the men applied to the handles is multiplied 632 times by the gearing and blocks. Two men are sufficient to move round the crane with 60 tonnes suspended from the extreme point of the jib.

A mechanical advantage of 632 to one means that each of the four men had to apply a force of only 23.7 kilograms in order to lift a weight of 60 tonnes – and this while operating a winch instead of a more efficient treadwheel. The most powerful crane in the world today (since September 2009) has a lifting capacity of 20,000 tonnes. If it would be equipped with a gear system offering the same mechanical advantage as that of the above described Fairbairn crane, a weight of 20,000 tonnes could be lifted by 1,265 men each exerting 25 kilograms of power. This is comparable to the workforce that was required to lift the 340 tonne obelisk in the 16th century. And of course, there is no doubt that we could further improve upon the 19th century gearwork and make the mechanical advantage even higher.

We could lift anything without fossil fuels. Nevertheless, apart from their use by some hardcore ecological architects, human powered cranes have completely disappeared, even for the lightest of loads. We prefer lifting things with power machinery and we run (not walk) on a treadmill in the gym to keep in shape. ←

Different types of pulleys. From 507 mechanical movements, Henry T. Brown, 1908.

Cranes with pulleys.

Erecting an obelisk using a lifting tower powered by multiple capstans on the ground.

Erecting an obelisk using a lifting tower powered by multiple capstans on the ground.

Erecting an obelisk using a lifting tower powered by multiple capstans on the ground.

Human powered cranes can still be found in the attics of some medieval cathedrals. Image from Historia koparek i pogłębiarek do początku XX wieku, Alfred Tadeusz Wislicki, 1995.

A treadmill at the attic of an English cathedral. From Medieval treadwheels: Artists’ views of building construction, Andrea L. Matthies, 1992, Society for the History of Technology.

Human powered crane on top of the Cologne cathedral, in use from 1400 tot 1842. Rheinisches Bildarchiv Köln.

Harbour crane with two treadwheels in Bruges, Belgium.

A harbour crane on a historical map.

Treadwheel crane to haul up boats on land, the Netherlands, 1900.

References

Bachmann, Oliver (1997). The History of Cranes. Wadhurst, East Sussex: KHL Group. (This book gives a detailed overview of lifting devices from the earliest times to the end of the 20th century. It also showed me the way to many great pictures.)

Fairbairn, William (1860). Useful information for engineers. London: Longman, Green, Longman, and Roberts, pp. 282-363. (The first edition of this book – all later editions do not contain the chapter on hand powered cranes – gave proof of the impressive performance of late hand powered cranes.)

Marks, Edward C. R. (1904). The construction of cranes and other lifting machinery. Manchester: The Technical Publishing Co. Ltd. (Detailed information on late hand powered cranes.)

Wikipedia, The Free Encyclopedia, s. v. “Crane”, http://en.wikipedia.org/wiki/Crane_%28machine%29. (General introduction, based on two authoritative German books.)

Wikipedia, The Free Encyclopedia, s. v. “List of historical harbour cranes”, http://en.wikipedia.org/wiki/List_of_historical_harbour_cranes.

Philip, Claude. Documents Claude Philip (website, 2019), http://pagesperso-orange.fr/claude.philip/documents/index.htm (illustrations of cranes).

Bessoni, Jacobi (1582). Theatrum instrumentorum et machinarum, Lugduni: Apud Barth. Vincentium …. (Ancient and medieval crane types.)

Kirby, Richard Shelton (1990). Engineering in History. New York: Dover Publications. (Extra information on ancient Roman and Egyptian lifting devices.)

Coulton, J. J. (1974). “Lifting in early Greek architecture”, The journal of Hellenic studies, Vol. 94, pp. 1-19.

Glynn, Joseph (1849). Rudimentary treatise on the construction of cranes and machinery. London: John Weale.

[1]: Oleson, John P. (2008). The Oxford Handbook of Engineering and Technology in the Classical World. Oxford: Oxford University Press. (Here I found most of the information on the mechanical advantage of lifting devices.)

[2]: Rihll, T. E. (2004). “Greek and Roman Science and Technology, V3: ‘Mechanics’”, Swansea University, March 11, 2004. Accessible through http://www.swan.ac.uk/grst/Specific%20subjects/Mechanics/Mechanics.htm.

[3]: Matthies, Andrea L. (1992). “Medieval Treadwheels: Artists’ Views of Building Construction.” Technology and Culture, Vol. 33, No. 3, pp. 510-547. (This study gives an informed look at medieval treadwheel cranes, inluding how to calculate the mechanical advantage of a treadwheel.)

[4]: Lancaster, Lynne (1999). “Building Trajan’s column”, American Journal of Archeology, Vol. 103, No. 3, pp. 419-439. (Roman lifting techniques & the use of lifting towers.)

[5]: Forbes Taylor, F. R. (1962). “Heavy goods handling prior to the nineteenth century”, Transactions of the Newcomen Society, Vol. 35, No. 1, pp. 179-191. (An overpriced research paper compared to that of Andrea L. Matthies, but it gives some interesting additional information on harbour cranes. Also names an estimation for the amount of medieval dockside cranes in Europe.)

[6]: Mayhew, Henry (1861). London labour and the London poor, vol. 3. London: Griffin, Bohn and Co.

[7]: Bachmann, Oliver (1997). The History of Cranes. Wadhurst, East Sussex: KHL Group.

Wood Gas Vehicles: Firewood in the Fuel Tank

During the Second World War, almost every motorised vehicle in continental Europe was converted to use firewood.

Wood gas cars (also known as producer gas cars) are a not-so-elegant but surprisingly efficient and ecological alternative to their petrol (gasoline) cousins, whilst their range is comparable to that of electric cars. Rising fuel prices and global warming have caused renewed interest in this almost-forgotten technology: worldwide, dozens of handymen drive around in their home-made woodmobiles.

Wood Gasification

Wood gasification is a process whereby organic material is converted into a combustible gas under the influence of heat – the process reaches a temperature of 1,400 °C (2,550 °F). The first use of wood gasification dates back to 1870s, when it was used as a forerunner of natural gas for street lighting and cooking. In the 1920s, German engineer Georges Imbert developed a wood gas generator for mobile use. The gases were cleaned and dried and then fed into the vehicle’s combustion engine, which barely needs to be adapted. The Imbert generator was mass produced from 1931 on. At the end of the 1930s, about 9,000 wood gas vehicles were in use, almost exclusively in Europe.

The technology became commonplace in many European countries during the Second World War, as a consequence of the rationing of fossil fuels. In Germany alone, around 500,000 producer gas vehicles were in operation by the end of the war. A network of some 3,000 “petrol stations” was set up [1], where drivers could stock up on firewood. Not only private cars but also trucks, buses, tractors, motorcycles, ships and trains were equipped with a wood gasification unit. Some tanks were driven on wood gas, too, but for military use the Germans preferred the production of liquid synthetic fuels (made out of wood or coal).

In 1942 (when the technology had not yet reached the height of its popularity), there were about 73,000 producer gas vehicles in Sweden, 65,000 in France, 10,000 in Denmark, 9,000 in both Austria and Norway, and almost 8,000 in Switzerland. Finland had 43,000 “woodmobiles” in 1944, of which 30,000 were buses and trucks, 7,000 private vehicles, 4,000 tractors and 600 boats. Woodmobiles also appeared in the US, Asia and, particularly, Australia, which had 72,000 vehicles running on woodgas [2]. Altogether, more than one million producer gas vehicles were used during World War Two. After the war, with gasoline once again available, the technology fell into oblivion almost instantaneously. At the beginning of the 1950s, then West-Germany only had some 20,000 woodmobiles left.

Research Programme in Sweden

Rising fuel prices and global warming have resulted in renewed interest in firewood as a direct fuel. Dozens of amateur engineers around the world have converted standard production cars into producer gas vehicles, with most of these modern woodmobiles being built in Scandinavia. In 1957, the Swedish government set up a research programme to prepare for a fast transition to wood gas cars in case of a sudden oil shortage. Sweden has no oil reserves, but it does have vast woodlands it can use for fuel. The goal of this research was to develop an improved, standardised installation that could be adapted for use in all kinds of vehicles.

This investigation, supported by car manufacturer Volvo, led to a great deal of theoretical knowledge and hands-on experience with several road vehicles and tractors over a total distance of more than 100,000 kilometres (62,000 miles). The results are summarized in a FAO document from 1986, which also discusses some experiments in other countries. Swedish and, particularly, Finnish amateur engineers have used this data to further develop the technology.

A wood gas generator – which looks like a large water heater – can be placed on a trailer (although this makes the vehicle difficult to park), in the boot (trunk) of a car (although this uses up nearly all the luggage space), or on a platform at the front or the back of the vehicle (the most popular option in Europe). In the case of an American pickup, the generator is placed in the truck bed. During WWII, some vehicles were equipped with a built-in generator, entirely hidden from view.

Firewood

The fuel for a wood gas car consists of wood or wood chips. Charcoal can also be used, but this leads to a 50 percent loss in the available energy contained in the original biomass. On the other hand, charcoal contains more energy, so that the range of the car can be extended. In principle, any organic material can be used. During the Second World War, coal and peat were also used, but wood was the main fuel.

One of the more successful wood gas cars was built last year by Dutch John. While many recent producer gas vehicles seem to come straight out of Mad Max, the Dutchman’s Volvo 240 is equipped with a very modern looking system made of stainless steel. “Producing wood gas is not that hard”, says John. “Producing clean wood gas is another thing. I have objections to some woodmobiles. Often, the produced gas is as clean as the appearance of the construction.”

Dutch John strongly believes in wood gas generators, mainly for stationary uses such as heating, electricity generation or even the production of plastics. The Volvo is meant to demonstrate the possibilities of the technology. “Park an Italian sports car next to a wood gas car and the crowd gathers around the woodmobile. Nevertheless, wood gas cars are only for idealists and for times of crisis.”

Range

The Volvo reaches a maximum speed of 120 kilometres per hour (75 mph) and can maintain a cruising speed of 110 km/h (68 mph). The “fuel tank” can contain 30 kilograms (66 pounds) of wood, good for a range of 100 kilometres (62 miles), comparable to that of an electric car. If the back seat is loaded with sacks of wood, the range is extended to 400 kilometres (250 miles). Again, this is comparable to the range of an electric car if the passenger space is sacrificed for a larger battery, as is the case with the Tesla Roadster or the electric Mini Cooper. The difference is, of course, that John has to stop regularly to grab a sack of wood from the back seat and refill the tank.

As is the case with other cars, the range of a wood gas car is also dependent on the vehicle itself. This is shown by the different cars that were converted by Vesa Mikkonen. The Fin places all his generators on a trailer. His most recently converted car is a 1979 Lincoln Continental Mark V, a large, heavy American coupe. It consumes 50 kilograms (110 pounds) of wood every 100 kilometres (62 miles) and is thus considerably less efficient than John’s Volvo. Mikkonen has also converted a Toyota Camry, a much more efficient car. This vehicle only consumes 20 kilograms (44 pounds) of wood over the same distance. However, the trailer is almost as large as the car itself.

The range of electric cars can be considerably improved by making them smaller and lighter. This is not an option with their wood gas cousins because of the weight and the volume of the machinery. The smaller cars from World War Two only had a range of 20 to 50 kilometres (12 to 31 miles), in spite of their much lower speed and acceleration.

Freedom

Enlarging the “fuel tank” is the only option to improve the range further (except for reducing one’s speed). American Dave Nichols can load 180 kilograms (400 pounds) of wood into the back of his 1989 Ford pickup truck. This takes him 965 kilometres (600 miles) far, a range that is comparable to a fossil fuel powered car. The merit of this is discussable, of course, as to do this, Nichols has to stop regularly to refill the tank: if he loaded the back of his pickup with gasoline, then he could drive even further.

According to Nichols, one pound of wood (half a kilogram) is sufficient to drive one mile (1.6 kilometres), which tallies with the Volvo’s 30 kilograms of wood per 100 kilometres. The American has set up a company (21st Century Motor Works) and plans to sell his technology on a larger scale. When he arrives home, he uses his truck to heat his house and generate electricity. His story has caught on in the US, and the reason can be summed up by his license plate: “Freedom”.

“You can go around the world with a saw and an axe”, as John Dutch puts it. His compatriot, Joost Conijn, grabbed this opportunity to take a two month trip throughout Europe, without worrying about the proximity of the closest of gas stations (which are not always easy to find in a country like Romania). The locals gave him wood to continue his journey – with the supply stored on a trailer. Conijn not only used wood as a fuel, but also as a construction material for the car itself.

Does the Woodmobile Have a Future?

During the 1990s, hydrogen was seen as the alternative fuel of the future. Then, biofuels and compressed air took over its mantle role, whilst today all the attention is focused on electric cars. If this technology fails, too (and we have expressed our doubts about it several times), can we go back to the wood gas car? Despite its industrial appearance, a wood gas car scores rather well from an ecological viewpoint when compared to other alternative fuels. Wood gasification is slightly more efficient than wood burning, as only 25 percent of the energy content of the fuel is lost. The energy consumption of a woodmobile is around 1.5 times higher than the energy consumption of a similar car powered by gasoline (including the energy lost during the pre-heating of the system and the extra weight of the machinery). If the energy required to mine, transport and refine oil is also taken into account, however, then wood gas is at least as efficient as gasoline. And, of course, wood is a renewable fuel. Gasoline is not.

The greatest advantage of producer gas vehicles is that an accessible and renewable fuel can be used directly without any previous treatment. Converting biomass to a liquid fuel like ethanol or biodiesel can consume more energy (and produce more CO2) than the fuel delivers. In the case of a wood gas car, no further energy is used in producing or refining the fuel, except for the felling and cutting of the wood. This means that a woodmobile is practically carbon neutral, especially when the felling and cutting is done by hand. Moreover, a wood gas car does not require a chemical battery, and this is an important advantage over an electric car. All too often, the embodied energy of the latter’s enormous battery is forgotten. In fact, in the case of a producer gas vehicle, the wood behaves like a natural battery. There is no need for high-tech recycling: the ash that remains, can be used as a fertilizer.

A properly-operating wood gas generator also produces less air pollution than a gasoline or diesel powered car. Wood gasification is considerably cleaner than wood burning: emissions are comparable to those of burning natural gas. An electric car has the potential to do better, but then the energy it uses should be generated by renewable sources, which remains to be seen.

The Drawbacks of Wood Gas Cars

In spite of all these advantages, it takes just one look at a woodmobile to realize that it’s anything but an ideal solution. The mobile gas factory takes up a lot of space and can easily weigh a few hundred kilograms – empty. The size of the equipment is due to the fact that wood gas has a low energy content. The energetic value of of wood gas is around 5.7 MJ per kg, compared to 44 MJ/kg for gasoline and 56 MJ/kg for natural gas.

Furthermore, the use of wood gas limits the output of the combustion engine, which means that the speed and acceleration of the converted car are cut. Wood gas consists roughly of fifty percent nitrogen, twenty percent carbon monoxide, eighteen percent hydrogen, eight percent carbon dioxide and four percent methane. Nitrogen does not contribute to the combustion, while coal monoxide is a slow burning gas. Because of this high nitrogen content, the engine receives less fuel, which leads to a 35 to 50 percent lower output. Because the gas burns slowly, a high number of revolutions is not possible. A producer gas vehicle is no sports car.

Even though some smaller cars have been equipped with wood gas generators, the technology is better suited to a larger, heavier car with a powerful engine. If not, engine output and range might not be sufficient. Even though the installation can be made smaller for a smaller vehicle, its size and weight do not decrease proportionately with the decreasing size and weight of the car. Some have built wood gas-powered motorcycles, but their range is very limited. Of course, the weight and size of the mobile gas factory is less an issue with buses, trucks, trains or ships.

Ease of Use

Another problem of wood gas cars is that they are not particularly user-friendly, although this has improved compared to the technology used in the Second World War. One contemporary report suggested that “experience at the Wurlitzer organ could be a distinct advantage” in order to drive a wood gas vehicle [3].

Still, in spite of the improvements, even a modern woodmobile requires up to ten minutes to get up to working temperature, so you cannot jump in your car and drive away immediately. Furthermore, before every refill, the ashes of the last gasification process have to be shovelled out. The forming of tar in the installation is less problematic than it was 70 years ago, but the filters still have to be cleaned regularly. And then there is the limited range of the vehicle. All in all, it is a far cry from the familiar ease of use of a gasoline car.

The large amount of (deadly) carbon monoxide produced calls for some precautions, too, since a leak in the piping is not impossible. If the machinery is placed in the trunk, the instalment of a CO-detector in the passenger compartment is by no means a luxury. Moreover, a wood gas car must not be parked in an enclosed space unless the gas is flared first.

Of course, all the vehicles described above are built by amateur engineers. If we build cars especially designed to be powered by wood, and produce them in factories, chances are that the drawbacks would become somewhat less significant and the advantages would become even greater. Such woodmobiles could also look more elegant. The Volkswagen Beetles that rolled off the assembly line during World War Two had the whole wood gasification mechanism built in. From the outside, the wood gas generator and the rest of the installation was invisible. Refilling was done through a hole in the bonnet (hood).

Deforestation

Unfortunately, wood gas shares an important disadvantage with other biofuels. Mass producing woodmobiles would not solve this. Quite the contrary, in fact: if we were to convert every vehicle, or even just a significant number, to wood gas, all the trees in the world would be gone and we would die of hunger because all agricultural land would be sacrificed for energy crops. Indeed, the woodmobile caused severe deforestation in France during the Second World War. Just as with many other biofuels, the technology is not scalable.

Yet, while a biofuel-powered car is as user-friendly as a gasoline rival, wood gas has to be the most user-unfriendly alternative fuel that exists. This can be an advantage: a switch to wood gas cars can only mean that we would drive less, and that would of course be a good thing from an environmental viewpoint. If you need to preheat your car for 10 minutes, chances are you will decide not to use it to drive a few miles to pick up some groceries. A bicycle would do the job faster. If you had to cut wood for three hours just to make a trip to the beach, you would probably decide to take the train.

In any case, the woodmobile demonstrates that the modern car is a product of fossil fuels. Whatever alternative fuel you believe in, none of them comes even close to the convenience of gasoline or diesel. If, one day, the availability of (cheap) oil comes to an end, the omnipresence of the automobile will be history. But the individual vehicle will never die. ←

A newly built wood gas car, parked next to a wood gas vehicles from the 1940s. Image: Dutch John.

Wood gas powered Volvo, built by Dutch John.

Detail of wood gas powered Volvo, built by Dutch John.

A modern DIY woodgas vehicle. Juha Sipilä.

Wood gas trailer built by Vesa Mikkonen in Finland.

Wood gas vehicle.

A vehicle powered by a woodgas trailer.

A wood-gas powered car, Berlin, 1946. Note the secondary radiator, required to cool the gas before it’s introduced into the engine. Bundesarchiv, Bild 183-V00670 (CC-BY-SA 3.0).

A wood gas vehicle with the installation hidden in the trunk.

A Belgian bus with a wood gas generator on a trailer. Image: Menno Huizinga, Netwerk Oorlogsbronnen, Public domain.

Hanomeg chain tractor K50 wood gas.

References

Mechanical Wood Products Branch Forest Industries Division (1986). “Chapter 3 - Recent Swedish experiences with operation of vehicles on wood and charcoal gas” in FAO (1986). Wood gas as engine fuel (FA Forestry Paper 72). Also check out “3.3 - Producer gas vehicles recently operated in other countries”, available through http://www.fao.org/docrep/t0512e/T0512e0j.htm#3.3%20producer.

Mikkonen, Vessa. Renewable energy for housing and transportation (website). http://www.ekomobiili.fi/Tekstit/english_etusivu.htm.

Johan Linell, Johan (2007). Around Sweden with wood in the tank (website). http://www.vedbil.se/indexe.shtml.

Pearson, Chris (2006). “‘The Age of Wood’: Fuel and Fighting in French Forests, 1940-1944”, Environmental History, Vol. 11, No. 4, pp. 775-803.

You can find pictures on woodgas.nl, gengas.nu, holzgas.ch (Opel Kadett), gengas.nu and ekoautoilijat.fi

[1]: Byrne, Ian (2000). “1930s/40s German road maps (zapfstellenkarten): Non-Uniti companies”, Petrolmaps (website). Accessible through https://web.archive.org/web/
20140719122130/http://www.ianbyrne.free-online.co.uk/german30.htm.

[2]: Gasification Australia (website, 2007). Accessible through https://web.archive.org/web/20120119091508/http://www.gasificationaustralia.com/index.php?option=com_content&task=view&id= 15&Itemid=31.

[3]: Producer Gas and the Australian Motorist: An Alternative Fuel During the Crisis of 1939-45. A presentation to Engineering Heritage Victoria, Don Barlett, 21 February 2008. Accessible through h). For a description of what it was like to drive a wood gas car back then, see page 17 and further.

Gas Bag Vehicles

Wood gas cars were not the only answer to the limited supply of gasoline in World War One and Two. An even more cumbersome alternative came in the form of the gas bag vehicle.

Gas bag vehicles were built during World War One and (especially) World War Two in France, the Netherlands, Germany and England as an improvised solution to the shortage of gasoline. Apart from automobiles, buses and trucks were also equipped with the technology. The vehicles consumed town gas or street gas, a by-product of the process of turning coal into cokes (which are used to make iron).

Today, vehicles powered by compressed natural gas (CNG) or liquified petroleum gas (LPG) are quite practical. The fuel tank needs to be roughly twice as big as a gasoline fuel tank in order to get the same range. But the fuel used for gas bag vehicles during the World Wars was generally not compressed and had a much lower energy density than LPG or CNG. To replace one litre of gasoline, two to three cubic metres of gas was needed.

Practical Range

The only way to get a somewhat practical range, was to use an extremely large gas tank. Buses were better suited for this than automobiles – they had a full-length gas storage bag on a roof rack. It could be enclosed in a streamlined fairing but most often it was not. Private automobiles were equipped with a wooden framework which was fastened to the roof and the reinforced bumpers of the vehicle. It was hard to overlook a gas bag vehicle passing along.

To give an idea of the performance, a Dutch car from the 1940s carried a gas storage bag of thirteen cubic metres, which gave it a range of approximately fifty km (thirty miles) at an energy consumption of thirteen litres per km (22 mpg). The aerodynamics of gas bag automobiles were disastrous, so fuel economy was far from optimal.

Easy Repair

Witnesses to the vehicle passing by could easily see how much fuel was left: the gas bag was fully inflated at the start of a trip, and it deflated with every mile that was driven. The gas storage bags were made of silk or other fabrics, soaked in rubber (Zodiac was one of the manufacturers).

These bags were (and are) much cheaper and easier to build than metal tanks. They could also be repaired in a similar way to bicycle tyres. The bag was anchored to the roof using rings and straps. Some gas bag vehicles could operate alternatively on gas or gasoline. Switching between the two options could be controlled from inside the vehicle.

Compressed Gas

Although it was technically possible to compress town gas or street gas, this did not happen because of two reasons. Carbon monoxide, one of the components of town gas and street gas, disintegrates quickly when compressed, while hydrogen gas, another component, leaks away through steel tanks when it is compressed.

The only exception was the use of gas cylinders in France during World War Two, allowing for a smaller fuel tank or a better range. Natural gas was used in this case, which could be compressed without the drawbacks of compressing town gas. However, this configuration turned out to be more expensive and more dangerous.

No Smoking

It will not surprise anyone that gas bag vehicles had their risks. One obvious risk was fire, which could cause a gas explosion. As a result, people waiting for the bus were urged not to smoke. Another risk were bridges and other overhead obstacles. The driver needed to know the exact height of the vehicle and of the bridges that he or she planned to drive underneath.

Excessive speeds were not a good idea either. It was advised not to surpass a speed of fifty km/h (thirty mph), not only to maintain a decent range but also to make sure that the fuel tank would not fly off the vehicle. Strong side winds could present hazardous situations, too. Gas bag vehicles also suffered from carburator fires, loud bangs and engine damage.

Gas bag buses could still be seen in China in the 1990s, notably in the municipality of Chongqing where they were developed in peace time as a cheap public transportation option.

Thanks to Dutch John. ←

A gas bag vehicle from World War I.

A gas bag vehicle from World War II.

This Dutch old-timer carries a gas storage bag of 13 m3, which gave it a range of approximately 50 km (30 miles).

A French car powered by gas cylinders, World War II.

Gas bag bus operated by the Scottish Motor Traction Company, 1914-1918.

Storage tank of a gas bag bus.

A gas bag bus.

Gas bag buses in Shandong, China, 1965.

Gas station for buses.

References

H. P. (1941). “Uit de praktijk met Gas-Ballon-auto’s”, Auto Techniek, Vol. 5, No. 2, August, 1941,
pp. 25-33.

LaBarge, Dustin (2010). “The Gas Bag Bus: Weird Invention #1 of Many Strange Technologies”, Knoji (website), April 13, 2010. http://factoidz.com/the-gas-bag-bus-weird-invention-
1-of-many-strange-technologies/.

Trolley Canal Boats

Only four years after the first experimental trolleybus, an ordinary steam canal boat was adapted to a trolleyboat.

For many centuries, canal boats were propelled by men, horses or mules on the towpath beside the water. Before diesel power took over, engineers developed several interesting methods powered by electricity: trolleyboats, floating funiculars and electric mules. Many of these ecological solutions could be applied today instead of diesel engines. Because of the very low energy requirements, they could easily be powered by renewable energy, generated on the spot by water turbines located at sluices. One trolleyboat line is still in use.

From Trolleybus to Trolleyboat

As described in a previous article, trolleybuses and trolleytrucks would make a lot of sense these days because they could deliver electric transport for a bargain, using simple and existing technology. The same method was once applied to boats, too. Not for sea travel, of course, but for canal transport.

Some canal boats were also propelled by systems that resemble those of cable trains, and yet another method combined common railway technology with canal barges. All this happened at the turn of the twentieth century, mainly in France and to a lesser extent in Germany, in Belgium and (only experimentally) in the United States.

Up until the second half of the nineteenth century, canal barges were the main means of transporting goods over longer distances through regions where no good natural waterways existed. In all of Europe by the end of the 1800s, there were between 19,300 and 24,000 kilometres (12,000 and 15,000 miles) of canals. In the US in 1880, the total length of canals was around 7,200 kilometres (4,500 miles).

The Towpath

From the 1840s onwards the rapid progress of railways threatened to make these canal networks obsolete. In 1880, already 3,200 km (2,000 miles) of canals in the US had fallen into disuse because of the rise of the railroads. Canal boats, which had a capacity of up to 240 tons in the second half of the 19th century, were towed by horses or mules on the tow path (sails were not an option on most canals). This method was very efficient compared to non-motorised land-based transport; a horse could carry 10 times more cargo in this way than was possible when hauling a cart on the road. Compared to the new railways, however, the cargo capacity of animal powered barges was limited and the speed was low.

In most countries, animal traction remained the only method in use on the canals, until it was superseded by diesel engines in the 1930s or later, or until the canals fell into disrepair altogether (like in the United Kingdom). But, faced with the decline in traffic at the end of the 1800s, some governments and canal companies attracted engineers to look for more modern and efficient ways of boat propulsion to compete with the railways.

The obvious solution to canal barge transport was the steam engine – the same technology that kept trains going. Some canal barges were indeed converted to independent steam powered vehicles or towboats, but it soon became clear that this could not work when applied to large numbers of boats. The reason was the state of the canals. In those times, canals were simply a large ditch without reinforced banks. If all barges would be equipped with steam engines onboard, or towed by steam boats, then the wash of the screws (or paddlewheels) would have destroyed the banks of the canals in no time.

Another obstacle was the limited depth of most canals, not exceeding 2 to 2.5 metres (6.5 to 8.5 feet) and this only in the middle of the canal. This made higher speeds problematic, because the stern of a propeller powered boat comes to lay deeper in the water as speed goes up. A third problem of steam power was that the bulky engine took away cargo space, thereby lowering the efficiency of the transport system. This made that, even though steam boats already existed since the end of the 1700s, and many of them were in use on rivers and lakes, only 84 of them were operated on American canals in 1906.

Because of these challenges, another obvious method – electric boats powered by batteries – was no solution either. At the end of the nineteenth century, thousands of electric automobiles were in use on the streets. The first “automobile” or independent boat carrying its own battery was already demonstrated in 1838, and at the end of the 1870s one even made a trip across the English Channel. But, these boats were not suited for canal transportation. The propeller or paddlewheel would create the same wash as a steamboat, destroying the delicate canal banks. The batteries would take up almost all the cargo space.

Overview of Electrical Methods

Ultimately, engineers found the solution in electric propulsion without the use of batteries. Roughly, all methods can be divided in five classes:

• Trolley propeller towing – engine on the boat.

• Trolley submerged chain towing – engine on the boat.

• Funiculars – engine on the banks.

• Manned electric mules – engine on the banks.

• Unmanned electric mules – engine on the banks or over the water.

Most of these systems were initially powered by steam engines, and later adapted to electricity, which made them much more efficient and practical. Some systems were afterwards converted to diesel engines. With the exception of funicular boats, all electrical systems were fed by a trolley line. Apart from some regional success stories, none of these technologies found widespread use, in spite of the many successful tests. Peak oil and climate change were no concerns in those times. Most countries chose to further deepen out and reinforce their canals in order to allow self-propelled steam and, a bit later, diesel boats.

At the end of the article I will explain why it’s time to ditch these and finally give the trolley systems the attention they deserve; they are our best chance to develop a completely oil independent, land-based cargo transport network with a large capacity.

1. Trolley Propeller Systems

One of the first alternatives for animal power was the trolley propeller system. Only four years after the first experimental trolleybus, Frank W. Hawley adapted an ordinary steam canal boat to a trolleyboat (named after him), which was tested on the Erie Canal in the US in 1893. The two electric motors (of 25 HP each) powered two screw propellers and received current from a pair of wires suspended over the canal through two ordinary underbearing trolley poles. As the boat had more or less lateral movement, the contact arrangement had to be flexible, and as the canal could not be used as a return, a double metallic circuit had to be used. This necessitated two wires for boats going in each direction.

The trolleyboat turned out to be a better option than the battery powered electric boat, because the cargo space was mainly left intact – electric motors were smaller than steam engines and no batteries were needed. Moreover, the range of the boat was unlimited. However, as with battery powered electrical boats and steam barges, the propeller created a wash and thus posed similar problems to the canal banks. The only way around this was to lower the speed, which made trolleyboats not that attractive.

The trolley system was never installed on the Erie canal, and neither were other electrical propulsion systems, because eventually the canal – 566 kilometres (352 miles) long and the most important in the US – was deepened out and reinforced in 1918 to allow the use of self-propelled boats. A plan for a trolley powered ferry did not make it either. In 1903, the Germans experimented with a propeller powered trolleyboat on the Teltow canal. It was a very sophisticated machine, creating almost no wash because of a special arrangement of three propellers, but eventually the electric mule (see further) was preferred.

The only propeller powered trolleyboat line that was ever operated in a commercial way was installed along a 4 kilometre (2.5 miles) stretch of the Charleroi Canal in Belgium in 1899. The trolleyboats towed unpowered canal barges. The line formed part of a 47 kilometre (29 miles) long trajectory served by electric mules (see further) and was only operated for a couple of years.

2. Trolley Submerged Cable or Chain Towing

In Germany, France and Belgium, another system was en vogue: chain towing. This method (first put into practice by french engineer François Galliot) combined the trolley system described above with an alternative means of boat propulsion: a cable or chain laid at the bottom of the canal. It was lifted and passed over rollers or wheels on the boat, which firmly gripped the chain or cable. These rollers were rotated by a motor on the boat (on top or on the side) and as they revolved they pulled the boat along the waterway on the cable.

The general arrangement was very much the same as in the trolley propeller method, but instead of turning a propeller, the motor would revolve the hauling drums or machinery. An important advantage was that the system did not create a wash and was thus compatible with the shallow and delicate canals. Another advantage was that, instead of having a double contact wire and double contact trolley carriage, the cable could be used as the return conductor. As this would necessitate only one contact wire, the contact arrangement and switching devices would be simpler and thus cheaper.

Steam powered cable haulers were already operated at the end of the 1860s, mostly on rivers. Two of these navigated on a 125 km (78 miles) stretch of the Erie Canal in the US from 1873 to 1880, but they were said to interfere so much with other traffic that their use was discontinued. Towards the end of 1893 (the same year that a propeller powered trolleyboat was tested on the Erie Canal), the first electrically powered submerged flexible cable system was set up in the Bourgogne canal in France. The hauling machinery was operated by an electric motor on the boat, which received current from an overhead trolley circuit. Operation started in 1894 and the line remained in service for more than 20 years.

Tunnels

The 6 kilometre (3.7 miles) long track went through a 3.3 kilometre (2 miles) long tunnel (in Pouilly-en-Auxois) and replaced a steam powered cable hauler that was in use since 1867. That this electric system (and others, see further below) served to pass through tunnel was no coincidence. Most of the underground canals going through mountains and hillsides were too narrow for a towpath. This meant that the horses were led over the mountain while the boat was moved through the tunnel by human power.

This happened by means of men lying on boards across the top of the boats, literally walking on the ceiling and so legging the boat through the tunnel. These men could be the bargemen themselves, or people who offered this service to them (the leggers). Of course, this method was painstakingly slow, and thus these tunnels were the first to be equipped with submerged cable steam towers. However, because of the exhaust fumes, this propulsion method was not really compatible with the small space and so they were converted to electricity when this became technically feasible.

The installation at the Bourgogne canal gave great satisfaction and it was the first electrical boat propulsion system to be operated on a practical, commercial basis. Moreover, it was a zero-emissions transport system: the electricity was generated on both sides of the track by means of water turbines placed at the cascades of two successive locks, having a fall of 7.5 metres (24.5 feet). Apart from the ecological advantage, the use of renewable electricity made that the line was working at almost no cost.

Only Trolleyline Still in Use

Much later, in 1933, another line was set up on the Canal de la Marne au Rhin. This system is still in use today and replaced a funicular system. Also in this case, the trolley line was used to cross a subterranean tunnel (Tunnel de Mauvages) being almost 5 kilometres (3.1 miles) long. In 1936, the trolleyboat line was combined with electric mules that operated alongside the whole canal except for the tunnel itself (where there is no towpath). The system is still working today because the fumes of diesel powered barges (which have replaced the electric mules along the rest of the canal) would suffocate the bargemen in the long tunnel.

The method had some disadvantages, which prevented it from being used on a larger scale. The first was the difficulty in rounding curves. As the chain or cable was laying loosely at the bottom, it frequently came very close to the banks, so the boats could run into the banks and sustain damage. Secondly, if there were many locks along the canal, this necessitated the picking up and dropping of the cable a great number of times which caused considerable difficulty and loss of time. Therefore, submerged cable towing was mostly limited to straight stretches of canal without too many sluices.

3. Cable Towing (Funiculars)

French engineer Maurice Lévy was inspired by funiculars instead of trolleybuses. In 1888, he conducted a number of experiments with cable hauling in the neighbourhood of Paris, at the junction of the Saint Maur and Saint Maurice Canals. This point was especially selected because the canals meet at right angles and hence present peculiar difficulties in turning the boats. Contrary to the two systems described above, there was no motor or engine placed on the boat itself. The boats were propelled by a moving cable on each bank, carried on supports provided with pulleys, and operated parallel to the canal. The cable was moved by a fixed motor, also placed on the banks of the river, and the boats were attached to the cable by means of hauling ropes. The technology was also used for aerial ropeways and wire rope power transmission.

Protruding from the boat were suitable arms, to which devices were attached that were adapted to grip and hold the moving cable. The boat could be started or stopped by connecting or disconnecting the grip with the cable by suitable devices on the boat. The system allowed for a speed of 4 kilometres per hour (2.5 mph). The cable was installed a few yards from the edge, in order to leave the tow path free. The method was thus easy to combine with horse and mule powered canal boats (contrary to the methods described below). The pulleys were placed vertically on a straight line, and more or less inclined on curves.

The cable was provided with links to which the rope was affixed that hauls the boat along. These links, fixed between rings, were capable of revolving freely upon the cable so as to avoid troubles from the latter’s tension. In order to prevent the cable from jumping out of the pulley channels, it was kept in place by a small overriding roller, and the flanges of the pulleys were notched, so as to allow the hauling links to go by. At its starting point, the cable passed over three large pulleys, actuated by the steam engine, which is placed in a small power house on the edge of the canal. To the right, there was a fourth pulley carried by a small car fitted with a counterpoise which served to keep the cable uniformly taut.

Cable towing had some interesting advantages over the previous method. Just as with submerged chain towing, no wash was created. Furthermore, there was no need to place an engine onboard, which meant that no cargo space was sacrificed, and that existing barges could be used without any further adaptations, or without the use of a towboat. Moreover, taking turns and passing sluices went much smoother than with the submerged chain method described above.

In spite of obvious advantages, the experimental line was dismantled some years later (as happened with a similar experiment in Germany) and Lévy installed his only commercial system on the Aisne-Marne Canal, towing the barges through the 2.6 kilometre (1.6 miles) long Mont-de-Billy tunnel. It remained in use until the 1940s. The problem was that the Frenchman used steam engines to move the cable – in that time, he did not have much choice.

Every cable would be operated in lengths of about 8 kilometres (5 miles) each way from the power station, the outgoing cable being used for boats going in one direction and the return cable (after crossing the canal) for those going in the other way. Arriving at the end of each circuit, the boats would be disconnected from the cable, connected to the cable of the next circuit, and so on. This meant that each circuit would have required its own steam engine, and personnel to operate it, and this would have been prohibitively expensive.

Electrical Funiculars

Maurice Lévy was ahead of his time, because 10 years later the technology for electricity generation had much improved. The Americans designed a similar plan but using electrical generators, fed by a cheap source of power such as a waterfall at a sluice. In this case, not every circuit required its own generator, because the electricity could be transported. Unfortunately, as mentioned earlier, the US eventually chose to deepen and reinforce the canals to give way to self-propelled boats, and the plans were never realised.

Only one electrically powered funicular system was effectively built and operated, on two separate parts of the Canal de la Marne au Rhin. It was successfully tested in 1910 in Jarville, close to Nancy, and fully installed just before the start of the First World War, by another French engineer, Edouard Imbeaux. It replaced a submerged cable steam towboat (described above). One line was 7 km or 4.3 miles long (passing through the 5 km or 3.1 miles long tunnel de Mauvages), the other line was 5 km long (going through the souterrain de Foug). The speed of the cable could be adjusted in order to pass the sluices. The lines were operated until 1933, when they were replaced by the only trolley barge system still in use today (described above).

4. Motor Locomotive Haulage (Electric Mules)

The only method that found a widespread use, at least on a regional scale, adhered to the old method of haulage or towing by mules on the path next to the canal. But, for the slow and uneconomical animal, a more efficient mechanical mule was substituted, hooked up to a trolleyline. The machines were either run upon a track on the banks of the canal (this method being practically a railway along the banks, the boats being trailers connected by a 50 metre (165 feet) long tow line to the motor cars) or either run upon the towpath itself (this method somewhat resembling a land based trolleytruck convoy).

As with the animal powered systems, two persons were needed to operate the convoy: one on the banks (driving the locomotive or truck) and one on the boat (steering). Using this method none of the boats were equipped with a motor, which resulted in the same advantages as with the funicular system: any boat previously towed by mules or horses could be hauled in this way without any adaptations or the need for a specially designed towboat, and no wash was created, leaving the delicate canal banks untouched and eliminating the need for deeper waterways.

In France, after some years of unsuccessful experiments with common steam locomotives on the tow path (starting in 1873), the first electric horse was tested in 1895 by M. Galliot on the Bourgogne Canal. The vehicle was a small, three-wheeled trolleytruck. It drove on the tow path on metallic wheels (without the use of rails) and could haul a barge at a speed of 2.5 to 3 kilometres an hour (1.5 to 1.9 mph). This velocity was not much higher than that of an animal hauled barge, but the electric horse could tow considerably more weight.

The following year, the Société de Halage Electrique set up the technology on a 43 kilometres long stretch of the Canal de la Deûle and the Canal d’Aire, from Béthune to Douai (close to the city of Lille in Northern France, on the border with Belgium). After some initial difficulties, a year-round regular service was established from 1898 on. The track was soon lengthened to 55 kilometres (34 miles), including the Canal de la Dérivation de la Scarpe, all the way to Courchelettes. In 1900, around 120 of these engines were in use.

However, the metallic wheels had a detrimental effect on the tow path, and the maintenance costs shot up. The service was discontinued in 1904 and replaced by tractors on rails. Experiments with this technology had been conducted in 1902 on a one kilometre (0.6 miles) stretch of the Canal de la Sensée (connecting Courchelettes with the river l’Escaut). These tractors, devised by M. Chanay, were twice as powerful as the trolleytrucks (boasting 40 HP and weighing 6 tons) and could tow 3 to 4 barges at a speed of 3 kilometres an hour (1.9 mph). In 1904, the rail-based system was installed along the 28 kilometre (17 miles) long Canal de la Sensée and along the busiest parts of the 55 kilometres (34 miles) of canal previously serviced by the trolleytrucks. In 1907, around 30 tricycles (without rails) and 60 tractors on rails were operated on this 83 kilometre (51 miles) long trajectory, and a total of 3,408,764 tons of goods was transported (around 20,000 barge transports).

3,731 kilometres

The network was gradually enlarged and mechanical mules became a common sight on almost every canal in Northern and Eastern France. In 1940, they were used on 2,986 kilometres (1,855 miles) of canals. At its height, in 1958, the network was 3,731 kilometres (2,318 miles) long, of which 1,047 km (650 miles) on rails (using 1,700 tractors) and 2,684 km (1,667 miles) on tyres (using 770 tractors, mostly diesel powered by then – trolleytrucks were considered obsolete. Mechanical mules were operated until 1973.

Electric mules on rails turned out to be much more reliable on the towpath than trolleytrucks, being operational every day and both day and night. The trolleytruck system only worked during daylight (at night too many drivers would end up in the water) and it could not be operated in winter conditions. The use and maintenance of the track system was two times cheaper than the trolleytruck system, but because of the higher capital costs a trolleytruck system remained a better choice on sections where traffic was low.

Compared to mule traction, both mechanical systems were more reliable, cheaper and faster – crossing the Canal de la Sensée took one day compared to three to four days with mules. Still, horse and mule traction continued to coexist with mechanical traction (and self-propelled boats) until 1940, when it was abolished on most canals. The slower animals became too much of a nuisance for the mechanical tractors, even if they worked on the other bank of the canal. From that year on, only mechanical means were allowed to tow barges.

Belgium & Germany

Electric mules were also used in other countries, be it on a much smaller scale. The first electric mules were operated not in France but in Belgium. In 1901, a sixteen kilometre (9.9 miles) stretch of the canal between Brussels and Charleroi was equipped with electric mules (both on rails and on tyres) by Léon Gérard. This was later extended to 47 km (29 miles). As mentioned above, a short part of this line was (for some years) served by trolley towboats instead of electric mules.

The Germans started their experiments with common steam locomotives on the Finow Canal in 1890. The results were spectacular, these machines being able to tow seven barges at a speed of seven kilometres per hour (4.3 mph) without any noticeable wash created. However, the energy consumption was very high, which made the system uneconomical. In 1899, they tested an electric tractor on rails designed by M. Kottgen, an engineer of Siemens. It differed from the electric mules used by the French and the Belgians, using only one rail. On the side of the canal, these vehicles did not rest on a rail but on two much larger iron wheels. These large wheels were aimed to assure the stability of the tractor, but they had the disadvantage that they quickly caused deep grooves in the tow path. While initially developed to save costs in laying tracks, maintenance costs soared and the method was abandoned.

In 1903, the Germans installed a mechanical traction method similar to that of the French on a 1.3 kilometre (0.8 miles) stretch of the Teltow Canal, close to Berlin. In 1905 and 1906, the transport network was extended to 70 kilometres (43 miles) using 22 vehicles. It remained in service until 1945, when it was dismantled by the Soviets. The German vehicles were more sophisticated than those of the French. They were equipped with a system that regulated the speed of the boat while the speed of the tractor remained the same, by mechanically adjusting the length of the tow cable. In France, tractors started slowly and gradually increased their speed in order not to get pulled into the water by the barge. Another electric mule system worth mentioning, technically similar but used for different purposes, is the one that is still being operated on the Panama Canal. In this case, the electric mules guide rather than tow the much larger ships (which keep using their engines).

In the US, electric mules were tested, but none of them were ever put in operation. One exception was a short and partial service on the Erie canal in Ohio in 1900, over a distance of 67 kilometres (42 miles). It was meant to be extended along the entire length of the canal from Toledo to Cincinnatti, a distance of about 393 kilometres (244 miles). But, the company quickly went bankrupt and the already existing tracks were dismantled.

Two Barges Crossing

On the larger part of the canal trajectories in France, traction occurred only at one side of the canal. When two tractors going in opposite direction met, they switched barges and drove back to where they came from (one barge had to navigate over the sunken towline of the other). A similar method had been in use with mules and horses for centuries. On the Teltow canal in Germany and, later, on some canals in France, tracks were laid on both side of the canal, which made towing easier but more expensive.

One disadvantage of electric mules was that they interfered with the loading and unloading of goods. However, this could be bypassed with an extra dock and two tracks. To prevent the tractors from being pulled into the water by the barges, they were made very heavy, sometimes by using reinforced concrete. Furthermore, the rail on the side of the canal was placed a few centimetres higher than the other one.

As time passed, many different kinds of vehicles were put into action. Diesel powered trucks slowly replaced trolleytrucks, and in France as well as in Belgium common automobiles were used also. After World War One, even tanks and other military vehicles were used to tow barges, without much success. Smaller companies kept using animals as part of a mix of materials.

5. Unmanned Electric Mules

A final method, mainly researched by the Americans but eventually only applied in France, blended all of the previously described methods more or less together in what is probably the most bizarre of all systems. It consisted of an unmanned electric mule, operated from the barge, riding on a rigid rail or rack, or suspended in the air on a cable, parallel to the canal – either on the banks or over the water. The unmanned locomotives – to which the boats were attached by a tow line and an electric line for control – received current from a trolley line.

Many different systems were designed and tested, of which the system invented by Richard Lamb became the best known. In 1896, three years after the experiments with the Frank W. Hawley trolleyboat (described above), the Lamb system was tested on a 6 kilometre (3.7 miles) stretch of the Erie Canal (at Tonawanda) and on the Raritan Canal in New Jersey. The idea was to use cheap electricity generated by the Niagara waterfalls, but eventually nothing happened. In 1898, the Lamb system was tested on the Finow Canal in Germany, but the Germans decided in favour of electric mules.

With the Lamb system, on approaching another boat coming from the opposite direction, motors were stopped, cables were disconnected, and boats exchanged cables (and thus motors) and proceeded. Some other systems allowed for the passing of two barges without exchanging motors, even if the track was laid out only on one side of the canal. In the system designed by Joseph Sachs, for instance, a duplex structure was used on which the motors or haulers were run between the middle and upper end middle and lower rails. A similar rack system designed by Wood was tested on a part of the Erie canal in 1903. The results were very positive: four loaded boats were hauled at a speed of 7.2 km/h (4.5 mph), compared to 2.8 km/h (1.75 mph) for a mule towing one barge, and this without threatening the banks.

While the members of the commission before whom the experiments were conducted were satisfied with the success of the scheme, they decided to wait for the completion of the extension and deepening out of the canal network (the Barge Canal) before authorizing a permanent installation. But when this job was done, some decades later, diesel powered boats had become the norm. Another test, using a system designed by Stillwell and Putnam, was performed on the Lehigh canal in Pasadena in 1907. The experiments were successful and the canal company was convinced of the feasibility of the technique. Unfortunately, they calculated that to justify the expenditure, the canal required three times as much cargo volume, and that never happened.

The Americans strongly believed that the unmanned mule was the best electrical system to propel canal boats, while the French and the Germans found the system to be rather problematic and were convinced that manned mules (their invention) were a much better option. They only saw limited use for unmanned mules, for instance in tunnels and in ports – an obvious advantage of most of these unmanned systems was that they kept the banks of the canal free. This difference of opinions led to extensive comparisons in books and magazines, coming to opposite conclusions. Fact is, the Americans never put any electrical mules in practice, manned or unmanned, while the French used them both – the unmanned mules indeed only for specific uses.

The most spectacular application of unmanned mules was developed by the Frenchman Chéneau. The small 600 kilogram locomotives, suspended in the air on a cable, were known as zinzins and closely resembled the Lamb system. Parallel to the cable was trolleyline, which powered the motor. The system was installed in the 1920s and was used to enter and leave sluices on a few canals in northern and eastern France. The towing of barges through sluices happened mainly by men, not by mules or horses, because it was a rather complicated task. Some zinzins remained in service until the arrival of self propelled diesel boats. The Americans made interesting plans, though, like the idea to suspend a rail upon which the motor runs, over the canal. This method would have had the advantage of affording a direct pull, but the cost of construction would be substantially higher than with the other systems.

Bring Back the Trolleyboats!

All the above is more than a gallery of obsolete technology. Canal transport is already one of the most energy-efficient ways to transport goods. For every litre of fuel burned, a barge can carry a tonne of cargo for 127 kilometres (79 miles), compared to 97 km (60 miles) for a train and 50 km (31 miles) for a truck. Electrifying canals could boost this efficiency even further, bringing the possibility of a zero-emission transport system within reach.

These days many canals have reinforced banks, so trolley systems with a propeller would no longer pose a problem. However, especially interesting are those systems in which traction happens on land instead of in the water (all systems excluding a propeller), because they are extremely energy-efficient. To move a barge of a certain tonnage at low speeds, an electric mule (or any of the other systems described) needs an engine at least 4 times less powerful than when this engine would be placed on the boat itself, propelling a screw. Wheels are more efficient than propellers. This means that for every litre of fuel, a barge towed by a machine on the banks or via a chain on the bottom of the canal could carry a tonne of cargo for 500 kilometres (310 miles) – ten times more efficient than a truck or lorry.

Because many canals have locks and thus artificial height differences between water surfaces, renewable energy could be generated on the spot. The required electricity to power the barges could also be generated by wind turbines or solar panels, which would make a low emissions transport system also possible in flat countries. Because of the very low energy requirements, the investment in renewable energy would be relatively small (contrary to, for instance, the plans to charge electric cars). And as always, obsolete systems can be substantially improved with today’s technology and materials.

Of course, canal barges are much slower than trucks or trains. But, if they could haul cargo for almost nothing, it would still be an economical choice for many goods. This advantage would grow if oil prices would rise. Many abandoned canals could be put in use again, and even new ones could be built. Almost all methods above were designed for use on very shallow, trapezoidal low-tech canals, which were only 2 metres (6.5 feet) deep at the centre, and much less on the sides. These are not public works like the Panama Canal which would take decades and require thousands of workers (or energy guzzling machines) to build. This is something that might even be done on a community level. ←

Horses and mules pulling a canal boat on the towpath of the Erie Canal, US.

A shallow canal in Dijon, France. Image in the public domain.

A trolleyboat on the Teltow canal in Germany.

A trolleyboat on a canal in Germany.

A trolleyboat on the Erie Canal in the USA, 1893.

A commercially operated trolleyboat on the Charleroi canal in Belgium, 1899.

Infrastructure for electric trolley propeller boats.

Chain towing combined the trolley system with an alternative means of boat propulsion: a cable or chain laid at the bottom of the canal.

Chain towing combined the trolley system with an alternative means of boat propulsion: a cable or chain laid at the bottom of the canal.

Funicular boats were propelled by a moving cable on the bank of the canal.

Electric mule on rails, France.

Electric mule on rails, France.

Two electric mules: one with tyres and one on rails.

Electric mules on the Finow canal in Germany, 1899.

An automobile tows a canal boat.

The Lamb system: An unmanned electric mule, suspended in the air on a cable, tows a boat in an experiment on the Erie Canal, 1896.

The Wood system was another type of unmanned electric mule, tested on the Erie canal in 1903.

References

Tissandier, Gaston (1889). “Halage funiculaire”,
La Nature, Nr. 811, December 15, 1889, pp. 33-35.

“Gov. Flower’s trolley plan: he would equip the Erie Canal with electricity”, The New York Times, June 10, 1893, p. 4.

Commerford, Martin T. (1894). Electrical boats and navigation. New York: C. C. Shelley. (This book has many more technical details on the methods used).

“Electricity on the canals; another scheme for utilizing the trolley system”, The New York Times, January 21, 1894, p. 21 (electric mules).

de Bovet, M. A. (1895). “Traction mécanique des bateaux sur les canaux”, Mémoires et compte rendu des travaux de la Société des Ingenieurs Civils, Vol. 63, January 18, 1895, pp. 40-66.

“Trolleyline for Canalboats: contract signed for an experimental system of four miles - how it would be operated”, The New York Times, July 26, 1895, p. 9.

“Electricity on the Erie Canal”, The New York Times, September 28, 1895, p. 2.

“The Canal Trolley works well: succesful test of the new system of propulsion”, The New York Times, October 27, 1895 p. 1.

“Boats run by electricity, how the Lamb system has been found to work on the Erie”, The New York Times, November 24, 1895, p. 28.

Meyer, Georg (1906). Der Elektrische Schiffzug. München und Berlin: n.p.

Whitford, Nobel E. (1906). History of the canal system of the state of New York. Albany: Brandow Printing Company.

Countryman, William A. (1906). “Canals and other inland waters”, Transportation by Water Special Reports 1906, Washington: US Census Bureau, pp. 197-224.

Bousquet, M. P. (1908). “La traction électrique des bataux sur les canaux”, Mémoires et compte rendu des travaux de la Société des Ingenieurs Civils, Vol. 91, November 1908, pp. 924-955 (lots of technical details here also, but in French). Available through the online Cnum Archive.

Imbeaux, M. E. (1914) “Aplicaciones mecánicas:
Un neuvo systema de sirga funicular electrico para barcos”, Revista de Obras Publicas, Vol. 62, No. 1 (2020), pp. 288-289.

Desaunais, A. (1928). “Le canal de Bourgogne et son traffic”, Les Études rhodaniennes, Géocarrefour, Vol. 4, No. 1, pp. 115-156.

Bogan, Dallas. “Electric mule could propel a canal boat system”, in: Bogan, Dallas (1979). Warren County, Ohio and Beyond. Bowie Maryland: Heritage Press, p. 378. Accessible through https://web.archive.org/web/20120127062831/http://www.rootsweb.
ancestry.com/~ohwarren/Bogan/bogan103.htm.

Briggs, Jeannette (2008). “The canals of England and Wales and their history” on Canal Guide (website, 1999). https://www.canalguide.co.uk/canalhistory/.

De Frontenay, G. (2017) “Traction mécanique sur les voies navigables” on G. De Frontenay (website, 2010). http://papidema.chez-alice.fr/accueil/canal/Traction_vn.html (many pictures here).

n.a. (08/09/2008). “Le tunnel de Mauvages”, Bord à bord (website), accessible through https://web.archive.org/web/20140720213129/http://bordabord.org/news/le-tunnel-de-mauvages-1-3 (many pictures).

Sadowski Jr., Frank E. (2000-2017). The Erie Canal (website), http://www.eriecanal.org.

ECMT (2006). “Strengthening Inland Waterway Transport: Pan-European Co-operation for Progress”, ECMT Publication, August 14, 2006.

How (not) to Resolve the Energy Crisis

Increasing the share of renewable energy will not make us any less dependent on fossil fuels as long as total energy consumption keeps rising.

Renewable energy sources do not replace coal, oil or gas plants, they only meet (part of) a growing demand. Regardless of the increasing share of renewable energy sources, we burn up more and more fossil fuels every year.

This is the case in the US, in Europe and on a global scale, but to make my point I will start by analysing the situation in Spain and in the Netherlands, because both countries are regarded to be an example for their commitment to renewable energy.

Moreover, the Netherlands have a negligible share of nuclear energy and hydropower (sustainable according to some, not sustainable according to others), while in Spain these energy sources have remained unchanged over the last decade, which makes the calculations more clear.

Share of Renewables

Last week, Spain made headlines around the world with the news that it generated over 53 percent of its electricity by wind power alone, be it during an extremely windy night and only for some hours. There is no denying that the development of wind power in Spain is impressive. Electricity generated by wind power grew with 8,000 percent between 1996 and 2007, from 338 gigawatt-hours (GWh) in 1996 to 27,509 GWh in 2007.

With it, the share of wind power in electricity production grew from 0.2 to 9 percent [1]. In the Netherlands, the amount of “green” electricity increased by 400 percent between 1998 and 2008, from 2,300 GWh to 9,500 GWh. With it, the share of renewable energy (mostly biomass and wind) in electricity production grew from 2.5 percent to 9 percent [2].

This sounds great, especially when you compare it to the situation in the United States, where the share of renewable energy in electricity production (excluding hydropower) rose from 1.4 percent to 2.3 percent during the same period (1998-2008) [3]. Or, on a global scale, where the share of renewables rose from 1.12 percent in 1990 to 2.3 percent in 2006. Yet, just like the Americans and the rest of the world, the Spanish and the Dutch are now more dependent on fossil fuels than a decade ago, not less.

Total Electricity Production

The reason is, of course, that the total electricity production in both countries kept rising. In Spain, it went up from 174,246 GWh in 1996 to 303,293 GWh in 2007 (a rise of almost 80 percent in 11 years). The share of fossil fuels in electricity generation grew from 38 percent in 1996 to 59 percent in 2007, while the absolute amount of fossil fuels used for electricity generation grew from 67,651 GWh to 179,737 Gwh [4].

So, from 1996 to 2007 the amount of wind powered electricity in Spain grew with 27,171 GWh (around 30,000 GWh if you include the use of solar and biomass), and the amount of fossil fuel powered electricity grew with 112,086 GWh. Now please explain to me, what is so “green” and exciting about this trend?

You could argue that Spain went through an economic boom during the last decade, and that it was merely catching up with the rest of Europe. This is why it is interesting to look at the Netherlands, too. Dutch electricity production rose less spectacularly, from 92,000 GWh in 1998 to 105,000 GWh in 2008 (a rise of 14 percent in 10 years). The share of fossil fuels in electricity production in the Netherlands even dropped from 90 to 85 percent, but here also the absolute amount of fossil fuel generated electricity grew from 83,000 GWh in 1998 to almost 90,000 GWh in 2008 [5].

Thus, from 1998 to 2008 the amount of “green” electricity in the Netherlands grew with 7,200 GWh, while the amount of “non-green” electricity grew with 7,000 GWh. So today, the Dutch are more dependent on fossil fuels for electricity generation than they were in 1998.

Avoided Emissions

Of course, things could have been even worse: that is why policymakers and statisticians prefer to talk about “avoided use of fossil energy” and “avoided CO2-emissions”. The reasoning goes as follows: if we would not have built those wind turbines and solar panels, then we would have burnt up even more fossil fuels. But, who are we fooling here?

The Spanish would have “avoided” the same amount of emissions and fossil energy if they would have built not one wind turbine between 1996 and 2007, but had chosen to limit the rise of energy consumption to 84,915 GWh, instead of the recorded 112,086 GWh. If they would have done that, they would have been just as dependent on fossil fuels as they are today, and they would have emitted the same amount of greenhouse gases as they do today – all this without those 27,171 GWh of wind powered electricity. They would not have made headlines with it, though. Nobody would have noticed.

The same goes for the Dutch: they would have “avoided” the same amount of emissions and fossil energy if they would have limited the rise of energy consumption to 7,000 GWh, instead of the recorded 14,000 GWh.

Embodied Energy

In fact, this low-tech scenario would have been a more ecological and energy efficient choice, because both countries would have saved the energy required to produce those renewable energy plants and sources – solar panels, wind turbines and wood pellets. Green electricity is not generated by a “clean” energy source, but by a “cleaner” energy source.

Solar panels, wind turbines and wood pellets do not use gas or coal during their operation, but they do require energy for their production – and since they are mostly produced far away from the place where they are used these figures do not show up in national statistics of energy consumption.

Mind you: the embodied energy of wind turbines (and solar panels) is not a problem if they replace non-renewable energy plants, because in that case we do save energy and thus make progress. But, this is not the case, so the embodied energy of this added electricity generation capacity is definitely extra energy use.

We Do Too Much

This does not mean that coal plants are preferable to wind turbines and solar panels. In fact, if the Dutch had built the (7,200 GWh) renewable energy plants and not built the (7,000 GWh) non-renewable energy plants, the result would have been real progress. Likewise, if they would have frozen energy consumption at the 1998 level and built nothing – renewable nor non-renewable energy plants – again there would have been substantial progress.

They would be less dependent on fossil fuels and they would produce less CO2 and air pollution. The problem is that they did not do any of this. Or, better said, they did everything at the same time; constructing more renewable energy plants, constructing more non-renewable energy plants, and consuming more energy.

Piling Up Energy Sources

Again, this trend is not limited to Spain and to the Netherlands (see these figures [6]), and what is happening is not a new phenomenon either. What we are doing for more than 100 years now, is piling up energy sources. Today (in the Netherlands [7], Spain [8], the US and worldwide [6]) the absolute amount of coal consumed for electricity production is much larger than one century ago, when there was no talk of gas, oil and nuclear. The dirty coal of the beginning of the industrial revolution was not replaced by cleaner gas plants. The gas plants joined the coal plants.

Next, nuclear plants did not replace the existing coal and gas plants, they joined them. Today, with renewable energy, the same thing is happening. They address an energy demand that did not exist before. We use renewable energy sources to power an ever growing plethora of energy-sucking gadgets – and this will not get us anywhere.

Up until now, newer and cleaner energy sources have always been used to enlarge energy production, not to make it “greener”. The so-called greening of our electricity production, which generates so much talk, is still one hundred percent wishful thinking. We are not one step further than five, ten, twenty or even a hundred years ago. On the contrary, things get worse every day.

Relative Versus Absolute Figures

Much more important than what we do, is what we don’t do. The key to progress is scaling down non-renewable energy production, or at least keeping it at the same level. Instead of aiming for the development of more renewable energy, policymakers should do anything in their power to make sure that not one more kilowatt of non-renewable energy is added.

Problem is that all policy objectives are expressed in relative terms (as a percentage of total electricity production) and never as absolute figures. The European Union aims to generate 20 percent of total electricity production by wind energy and 15 percent by solar energy in 2020 [10]. The US aims to generate 25 percent of its electricity from renewable sources by 2025 [11]. None of their reports describe any goal in absolute figures. This is a fruitless approach as long as total electricity consumption is on the rise.

United States

For instance, imagine that the US indeed realises the very ambitious goal of generating 25 percent of their electricity consumption by renewables, and let’s assume it takes them 5 years longer as planned. According to the projections of the EIA, US electricity demand will grow by 26 percent [12] from 2007 to 2030. This means that the 3,800,000 GWh of today will be 4,788,000 GWh by 2030. When everything goes to plan, about 1,244,880 GWh of that will then be renewable (that is three times the worldwide renewable electricity capacity today).

But, this is scarcely more than the 988,000 GWh of electricity demand that will be added during that period. So even if this ambitious goal would be realised, the US would still be as dependent on fossil fuels as it is today. Limiting electricity demand to current levels and not building any renewable electricity generating capacity would yield the same result. Limiting electricity demand to current levels and greening 25 percent of the existing electricity production would bring real progress.

Worldwide

The rise of renewable energy is of secondary importance. What matters is that the absolute amount of burned up fossil fuels lowers. Only then would we become less dependent on non-renewable energy sources and on foreign energy suppliers, and only then would we lower CO2-emissions.

On a global scale, the futility of the present approach is even more obvious. The total amount of renewable electricity worldwide (excluding hydro) rose from 31,000 GWh in 1980 to 414,000 GWh in 2006 – a rise of 1,300 percent or an absolute increase of 383,000 gigawatt-hours. Yet, the amount of electricity generated by coal and gas doubled in that same period, which comes down to an absolute increase of 6,355,900 Gwh.

So, we added around 20 times more non-renewable sources than renewable sources. Total global electricity production rose from 8,027,000 Gwh to 18,008,000 Gwh, a rise of 250 percent. If we look at total energy production instead of just electricity production, the preponderance of fossil fuels is even larger.

This trend does not seem to come to an end soon. Last week, the International Energy Agency (IEA) published its World Energy Outlook 2009, which looks forward to 2030. According to the organisation, energy consumption will rise by 40 percent between now and 2030. This will happen in spite of the fact that global energy consumption decreased in 2009 owing to the economic crisis. The IEA expects electricity consumption to rise with another 76 percent in 2030, which equals a required capacity of 4,800 gigawatts – almost 5 times the present capacity in the United States.

Even if we succeed in building 4,800 gigawatts of renewable energy in the coming 20 years (something which is rather unrealistic), we would still not be one step further than we are today. What we have to deal with is that which is almost regarded as an unshakable natural law – the non-stop growth of energy use.

How to Solve the Energy Crisis

Don’t get me wrong: all efforts to build and develop renewable energy and energy efficient technology are useful and very necessary. My point is that, by themselves, they will not yield any results. To make them work, we need to put an absolute limit to energy use.

Imagine that the European Union or the US would decide that in 2020 we can only use as much energy (or electricity) as we do today. Interestingly, all other efforts suddenly make sense. If the share of renewable energy would rise, then the share of non-renewable energy would automatically fall. Energy efficient technology would be automatically transformed in energy savings, and not in extra applications or performance, as it happens now (the energy efficiency paradox).

In this scenario, with every small step forward in renewable energy production and energy efficient technology, we would become less and less dependent on fossil fuels, and we would emit less and less greenhouse gases. Moreover, it is hard to call this measure drastic or radical: if we can manage today with 18,008,000 Gwh, why not in 2030? What more energy-sucking gadgets do we need?

Not China’s Fault

Last, but not least, the IEA notes that the rise of energy use is largely on account of non-western countries, with China ahead. But, this does not clear us at all. As the IEA calculated in a former report, almost thirty percent of energy use in China comes from the production of export goods – from bicycles over jeans to solar panels.

Western countries succeed in limiting the rise of their energy consumption because they have outsourced ever more energy use. Moreover, the IEA states in its last report, non-OECD countries are, in spite of their high share in current energy use, only responsible for 42 percent of the CO2-emissions since 1890 – with a much bigger population. This means that – in a fair world – we would have to reduce our energy use much more than them.

Note: Although this article dates from 2009, a recalculation done in 2019 for the reference year 2017 gives similar results. ←

References

Energy Statistics

World: Institute for Energy Research,
www.iea.org/statistics/.

US: Energy Information Administration,
https://www.eia.gov.

Europe: Eurostat, https://ec.europa.eu/eurostat.

The Netherlands: Centraal Bureau voor Statistiek, https://www.cbs.nl/nl-nl/cijfers.

Spain: Instituto Nacional de Estadística, http://www.ine.es/dyngs/INEbase/en/listaoperaciones.htm.

[1]: Eurostat (2007). Energy: yearly statistics. Luxembourg, Office des Publications Officielles des Communautés Européennes.

[2]: Centraal Bureau voor de Statistiek & StatLine (2019). Tabel: “Elektriciteit en warmte; productie en inzet naar energiedrager”. https://opendata.cbs.nl/statline/#/CBS/nl/dataset/80030NED/table?fromstatweb.

[3]: U.S. Energy Information Administration (2012), “Independant statistics and analysis: Table 8.2c Electricity Net Generation: Electric Power Sector by Plant Type, 1989-2011, EIA, September 27, 2012. https://www.eia.gov/totalenergy/data/annual/showtext.php?t=ptb0802c.

[4]: Eurostat (1996). Energie: Jährliche Statistiken = Energy: yearly statistics = Énergie: statistiques annuelles. Luxembourg, Office for Official Publications of the European Communities.

[5]: Wezel, Bart van; Centraal Bureau voor de Statistiek (2009). “Productie fossiele stroom onverminderd hoog”, April 22, 2009.
http://www.cbs.nl/nl-NL/menu/themas/industrie-
energie/publicaties/artikelen/archief/2009/2009-2761-wm.htm.

[6]: U.S. Energy Information Administration (2012). Annual Energy Review 2011.

[7]: Centraal Bureau voor de Statistiek & StatLine (2019). Tabel: “Kolen en kolenproducten; winning, in- en uitvoer, productie; vanaf 1802”. https://opendata.cbs.nl/statline/#/CBS/nl/dataset/71554ned/table?fromstatweb.

[8]: Eurostat (2007). Energie: Jährliche Statistiken = Energy: yearly statistics = Énergie: statistiques annuelles. Luxembourg, Office for Official Publications of the European Communities.

[9]: Institute for Energy Research (2008). “U.S. Consumption by Source v. Real GDP 1845-2001”. Accessible through http://web.archive.org/web/20130602082313/http://www.instituteforenergyresearch.org/pdf/2008/General%20Energy%20Charts%20and%20Info/Energy%201%20-%20US%20Consumption%20v.%20GDP%201845-2001.jpg.

[10]: European Commission, “Strategic Energy Technology Plan”. http://ec.europa.eu/energy/technology/set_plan/set_plan_en.htm.

[11]: Union of Concerned Scientists (2009), “25-Percent-by-2025 National Renewable Electricity Standard Would Create Nearly 300,000 Jobs, Save Consumers Billions, Science Group Says” (press release), March 23, 2009, https://web.archive.org/web/20091015121329/http://www.ucsusa.org/news/press_release/25-by-2025-RES-0209.html.

[12]: International Energy Agency, Annual Energy Outlook 2011.

Rings of Fire: Hoffmann Kilns

The Hoffmann kiln was a nineteenth century brick and tile production technique that is surprisingly energy efficient.

A Hoffmann kiln, ring oven or ring kiln was a massive oven in which clay was baked at a temperature of around 1,000 °C (1830 °F) to produce bricks and tiles. It was a circular, elliptical or rectangular brickwork structure that consisted of an endless tunnel, divided into 12 to 24 chambers, all interconnected to each other and to a main flue leading to a large chimney. Each of the chambers also had an opening through which the bricks were loaded and unloaded, to be closed by a door or a temporary brick wall.

The chambers were filled with bricks (some 25,000 of them) and fired one after the other. The heat in one chamber was not only used to bake the bricks inside, but also to preheat the still to be fired bricks in the succeeding chambers. Meanwhile, air that was drawn in, through the door of the chamber where bricks were unloaded, travelled in the opposite direction and cooled down the already baked bricks in the preceding rooms. The fire was “chased” around the building in a never ending process that was extremely energy-efficient. Depending on the size of the kiln, it took between one and six weeks for the fire to complete a full circle.

The ring oven was patented in Germany by Frederick Hoffmann in 1858. It revolutionised the brick and tile production industry because of multiple reasons: it allowed for a better and more uniform quality of ceramic goods, it was much more economical both in terms of fuel consumption and labour costs, and it raised the production output spectacularly – up to 10 million bricks per factory per year. Population was growing fast at the beginning of the industrial revolution and brick producers were struggling to keep up with demand. The Hoffmann kiln allowed for mass production of bricks and tiles, but despite its complexity the whole firing process was executed without the use of machines.

Continuous Production

The Hoffmann kiln is a so-called continuous kiln – it burns 24 hours a day, 7 days a week, 365 days a year (except when it goes down for maintenance). Before its invention, bricks and tiles were fired in so-called periodic kilns. This method was very time-consuming because it is essential to ensure that ceramic materials are not heated up and cooled down too fast. This meant that the fire had to be increased very slowly and carefully, and that the baked bricks had to remain in the oven several days after the fire was extinguished. During this time, the periodic kiln could not be used to bake a new stack of bricks. Moreover, the structure itself had to be heated up every time, and during the firing process most heat was lost through the chimney or the roof, wasting large amounts of fuel.

The original Hoffmann kiln was circular in plan with a large chimney placed at the centre, but this shape was abandoned quickly for an elliptical outline, and ultimately a rectangular shape with two parallel tunnels built side by side, connected by curved tunnels at either end. The chimney could be in the middle, or next to the building. A rectangular kiln saved space, was easier to operate and allowed for a more homogeneous air circulation.

Some Hoffmann kilns were fuelled by gas, but mostly the fuel was coal. The ceiling of a ring oven contained many rows of openings – covered with air-tight metal caps – which were known as feed holes. Experienced stokers dropped a small and precisely dosed amount of crushed coal through the holes above the chamber that was fired, using a small coal shovel. They formed a team with the setters, who built the stacks of unfired green bricks inside the chambers. These stacks were positioned so that they contained flues and channels to ensure even baking. Right underneath each feed hole the bricks were arranged to form fireplaces, in which the fuel could be burnt. These were hollow shafts built of bricks, with occasional projecting bricks to prevent all the fuel from falling directly to the bottom.

Once the stacks were built, the chamber was closed by a door or a temporary brick wall, not to be opened again before unloading the bricks several weeks later. It was not necessary to enter the chambers to light the fire: once a room was preheated enough by the hot gases of the chambers next to it, the temperature inside was high enough to spontaneously combust the coal that was dropped through the feed holes.

How it Works

In Cement, concrete and bricks, a book published in 1914, Alfred B. Searle gives a clear and detailed description of the exact working of a rectangular Hoffmann kiln on the basis of a drawing. In spite of its length, his explanation is highly rewarding, so here it is – slightly adapted – in its entirety:

Assuming that the kiln is in full work, what takes places is as follows: the fuel is fed into the feed holes covering three chambers (1, 2 and 3). A light charge of fuel is being placed in each hole every quarter of an hour. Number 1 will be almost finished. The hot gases from the burning fuel will be carried by the draught through the five succeeding chambers (4, 5, 6, 7 and 8) and will gradually pre-heat the bricks without requiring any attention. After this the gases will be of so low a temperature that they are not longer useful and are taken through the flue in chamber 8 into the main flue and so to the chimney. All the dampers to the main flue in chambers 1 to 7 are meanwhile kept closed, so that all the available heat is used in warming the bricks to be fired.

Chambers 9, 10 and 11 contain freshly-set bricks and these must be separated from the remainder of the kiln. Their temperature must be raised to at least 120 °C (248 °F) by a separate supply of heat; to heat them by waste gases would usually cause them to be badly scummed, though for some purposes this would not matter and they may then be taken at once into what is termed “the round of the kiln” without any preliminary heating. Ordinarily, however, the bricks must be heated by as pure air as possible, until their temperature is such that no condensation products can form upon them. The purest warm air obtainable is that which is drawn through the chambers containing cooling bricks (14, 15 and 16), and many kilns have specially arranged flues for the supply of warm air for this purpose.

As soon as the bricks have reached a temperature of about 120 °C (248 °F) the partition between chamber 8 and chamber 9 is removed. The damper to the chimney in chamber 8 is closed and the supply of warm air to number 9 is shut off. The hot gases from the fuel then pass into chamber 9 and the latter is said to be “taken into the round of the kiln”. Meanwhile, chamber 12 has been filled and chamber 13 is empty or being emptied. Chambers 14, 15 and 16 contain bricks which are cooling, this being accomplished automatically by the draught of the kiln which draws cool air through the open doorway of chamber 13. The air thus admitted first comes into contact with almost cool bricks, and becomes gradually hotter taking heat from the cooling bricks in its journey until, when it reaches the burning fuel in chambers 1, 2 and 3, it is of the same temperature as the hottest bricks in the kiln and ensures, with careful management, a very complete combustion of the fuel with scarcely any avoidable waste of heat.

Any description of the working of a continuous kiln must, necessarily, appear complicated, but in reality these kilns are quite simple. As soon as a chamber is filled, its contents are first warmed by hot air, and then it is taken into the round of the kiln as described. It then needs no further attention until it has become so hot that a little fuel must be fed into it in order to complete the burning. As soon as the contents of this chamber have been heated sufficiently, the addition of coal to it is stopped, another chamber is taken into the round of the kiln, and so on; one chamber being emptied and another being filled continuously, and the fire travelling round and round the kiln in a perfectly regular and continuous manner.

It is clear that a Hoffmann kiln required a skilful and careful operation. If the temperature was too high, the bricks would come out misshapen. If the temperature was too low, the bricks would be weak and porous. If the bricks were heated up or cooled down too fast, this would result in cracked, warped or twisted goods. The man in charge of the kiln ascertained the completion of the burning by means of trials, shrinkage measurements and Seger cones. In a well operated Hoffmann kiln, on average only 3 percent of bricks were spoiled, but with inferior management this could be 50 percent.

Endless Tunnel

Apart from mismanagement, another risk was the weather. If a chimney is used to create draught, a storm will create irregular heating. Therefore, in some later kilns, large fans were positioned to obtain a more powerful and perfectly steady draught (also speeding up the production process). Large temperature differences also were a challenge. Although it simplifies the explanation of the Hoffmann system, in reality most of these continuous kilns did not really consist of 12 to 24 separated chambers.

The so-called chambers were basically theoretical sections of the endless tunnel that indeed could be separated from each other by very large metal dampers (which could be raised and lowered from the outside) or – later – sheets of paper or fabric (which were automatically torn apart at the right moment by the approaching hot air). But, at any time in the process, a maximum of 3 shutters were in effect and so a Hoffmann kiln in reality never contained more than 3 chambers – one being a very large one. The basic function of the shutters was to prevent the cold air drawn in from going the wrong way around the kiln.

Remarkably, the operation of the Hoffmann kiln closely resembles that of a wood burning tile stove – a very efficient heating appliance used since medieval times to warm the interior of buildings. In both cases, a complex system of flues and channels keeps the hot gases inside the oven as long as possible. Only when their temperature becomes so low that they are of no more use, the gases are allowed to escape through the chimney. This makes the burning process very energy-efficient (because almost all generated heat is put to use) and relatively clean (because of the complete combustion there is hardly any smoke leaving the chimney).

In a Hoffmann kiln the gases that come out of the chimney have a temperature below 130 °C (266 °F), whereas those from periodic kilns have a temperature of 800 °C (1472 °F) or even higher – wasting large amounts of fuel, similar to what happens in an inefficient wood stove. On average, the fuel consumption of a Hoffmann kiln is one-third that of a periodic kiln. Other similarities between tile stoves and Hoffmann kilns are that both emit heat continuously and only have to be fired from time to time to keep the process going. And just like an oven stove, a Hoffmann kiln becomes more energy efficient the larger it is. Therefore, one of the only drawbacks of Hoffmann kilns was that they required a large plot of land. Their minimum perimeter was at least 68 metres (224 feet) and some rectangular ovens were between 100 and 200 metres (328 to 656 feet) long.

There is also one major difference between ring ovens and tile stoves: a Hoffmann kiln has massive walls (around one metre thick) to provide a good insulation, in order to prevent the heat from escaping to the exterior of the building. In an oven stove this is not the case, because heating the exterior is what it is intended for. In spite of their energy efficiency, Hoffmann kilns were not clean and pleasant factories. The stokers were covered in black soot and people living around a kiln were not so happy with it, either. However, these side-effects have more to do with the era in which Hoffmann kilns were used than with the technology itself – coal was everywhere and chimneys were not equipped with scrubbers. Some ring ovens were fuelled by gas (again, just like some tile stoves), and in principle they could also be powered by a variety of biomass fuels, or (clean) electricity. There is no reason why a Hoffmann kiln today should be dirtier than a modern brick or cement plan.

Hoffmann Kilns With Multiple Fires

The Hoffmann kiln caught on fast – in 1870, a decade after the first one was built, there were already 639 units operating worldwide. It remained the most important technology to bake bricks, tiles and ceramic pipes for a century. The original design was adapted to many other forms, some of them rather spectacular. An important improvement to the Hoffmann kiln was made by Jacob Bührer from Switzerland. He generated great fuel efficiency and a large increase in output by the use of a continuous kiln with a tunnel about twice as long and half as wide as those commonly in use. In order to overcome the difficulties of construction and loss of heat inherent to an extremely long and narrow kiln, Bürher arranged his tunnel in a zigzag manner. Whilst externally his kiln is square in plan, its effective tunnel length is almost double that of a Hoffmann kiln.

Where very large outputs were required, shank kilns were built. These combined several kilns in the shape of a cross or a star. Several fires could be kept going in each kiln with a minimum of labour, and the cost of erection was less than that of several continuous kilns of equal total capacity. At the beginning of the twentieth century, already over 200 of these shank kilns were in existence on the continent with an annual output varying from 5 million to 50 million bricks each. A continuous kiln was sometimes enlarged by adopting the Shank principle just described. In enlarging a kiln this way it was mostly necessary to supplement the chimney-draught by the aid of a fan. Some large continuous kilns were also equipped with several chimneys.

Hoffmann Kilns in Use Today

Today, ring ovens (and some alternatives) are still used in “developing” countries, and by some artisanal producers of traditional bricks in the developed world – their products being mostly aimed at the renovation of historical buildings. In some countries a low-tech version of the Hoffmann kiln is used, in which the arched roof is replaced by a cover of bricks and sand. These are called Bull’s trench kilns – named after its British inventor W. Bull – and they are common in Pakistan, India, Bangladesh, Nepal and Myanmar. These semi-continuous kilns – 100 to 150 metres long and usually built in a trench – produce bricks of similar strength, but with a lesser esthetic quality. In a Bull’s trench kiln the light sheet metal chimneys are moved around every 24 hours by a team of workers in order to fire a different part of the tunnel.

These kilns are less efficient than a real Hoffmann kiln, but still more efficient than periodic kilns. Their great advantage is that they are cheaper to built. In a real Hoffmann kiln it is necessary to burn some six to ten million bricks before the saving in fuel has compensated the cost of the construction of the oven. During the second half of the twentieth century, most Hoffmann kilns in the industrial world were replaced by continuous tunnel kilns (which were already patented in 1877 by another German, Otto Bock).

In a tunnel kiln, the process of the Hoffmann kiln is turned upside down. In a Hoffmann kiln the bricks stay where they are and the fire moves around, but in a tunnel kiln the fire remains stationary while the bricks move slowly through the tunnel. The fire is situated in the centre and the bricks slowly proceed through the tunnel on a train or a conveyor belt, so that bricks which are in the beginning of the tunnel are slowly being preheated by the fire further on, and bricks which have passed the fire are allowed to cool down gradually. Tunnel kilns are much more expensive to build than Hoffmann kilns, but they save on labour costs because they can be highly automated – today they operate without a human in sight. Still, in spite of all that high-tech, they are not more energy-efficient than Hoffmann kilns – both processes require around 2,000 kilojoules per kilogram of brick.

If compared to some improved versions of Hoffmann kilns, a tunnel kiln is even less energy efficient. Moreover, in modern brick production facilities all too often energy efficiency is sacrificed for speed and the drying and cooling processes are fastened by means of extra energy inputs. The reason for the existence of a tunnel kiln is that the production process is further accelerated, resulting in a much larger output of bricks. This might as well be the most devastating aspect of modern brick production, because there seems to be a correlation between the speed of production and the ease with which we build and demolish buildings. ←

A Hoffmann kiln in Nivaagaard, Denmark. Public domain.

The ruins of a Hoffmann kiln. Image by Berend Jan Stijf (CC-BY-SA 3.0).

A Hoffmann kiln in Germany (CC-BY-SA 3.0).

Hoffmann kiln with two chimneys.

Plan of a Hoffmann kiln.

How the Hoffmann kiln works.

Different designs of Hoffmann kilns.

The interior of a Hoffmann kiln. Matthias Süssen (CC BY-SA)

The interior of a Hoffmann kiln. Image in the public domain.

Stacked bricks in a Hoffmann kiln. Public domain.

The interior of a Hoffmann kiln in Hungary (CC-BY-SA 4.0)

The ceiling of a Hoffmann kiln contained rows of openings – covered with air-tight metal caps – which were known as feed holes. Frank von Marillac (CC-BY-SA 3.0).

References

Searle, Alfred B. (1914). Cement, concrete and bricks. New York: D. Van Nostrand co.

Searle, Alfred B. (1911). Modern brickmaking. London: Scott, Greenwood & son. (Chapter 8 (p.243-367) has additional information on Hoffmann kilns.)

n.a. (2007). “Le grand four”, Musée des arts et métiers (website), accessible through https://web.archive.org/web/20100810151259/http://www.arts-et-metiers.net/musee.php?P=46&id=7&lang=fra&flash=f&arc=1.

Fidler, Henry (1889). Notes on building construction. London: Longmans, Green, and co.

Ure, Andrew & Hunt, Robert & Rudler, Frederick W. (1875). Dictionary of arts, manufactures, and mines containing a clear exposition of their principles and practice. London: Longmans, Green, and co., Vol. 3.

Jones, Tim (1995). Basics of Brick Kiln Technology. GATE (publisher). Braunschweig: Vieweg.

Wikipedia, The Free Encyclopedia, s. v. “Hoffmannscher Ringofen”, http://de.wikipedia.org/wiki/Hoffmannscher_Ringofen.

n.a., n.d. “Hoffmann kiln, Craven Lime Works”, Out of Oblivion (website), http://www.outofoblivion.org.uk/record.asp?id=296.

Lefêvre, Leon & Bird, K.H. & Moore Binns, W. (1900). Architectural pottery: bricks, tiles, pipes, enamelled terra-cottas, ordinary and incrusted quarries, stoneware mosaics faïences, and architectural stoneware. London: Scott, Greenwood & co.

Briqueterie DeWulf (website, s.d.), accessible through https://web.archive.org/web/20040320185632/http://www.briqueterie-d-allonne.fr/four%20Hoffman/four%20hoffmanfla.html.

Searle, Alfred B. (1914). Cement, concrete and bricks. New York: D. Van Nostrand co.

“Ziegeleien in Kathmandu in Nepal (2013)”, Nepal Dia (website). http://www.nepal-dia.de/K-Kathmandu-Tal/K-Ziegelei_Kathmandu/k-ziegelei_kathmandu.html

Norsker, Henrik. “Bull’s Trench Brick Kiln (2007)”, Basin (website, 2005). Accessible through https://web.archive.org/web/20070626152417/http://www.basin.info/gate/bull.htm.

“Tunnel Kiln for firing mechanised red bricks”, Sabin Enterprises (website, 2005). Accessible through https://web.archive.org/web/20050403125821/http://www.blockmachines.biz/tunnelkiln.htm.

Wind Powered Factories: History (and Future) of Industrial Windmills

In the 1930s and 1940s, decades after steam engines had made wind power obsolete, Dutch researchers obstinately kept improving the – already very sophisticated – traditional windmill.

More than 900 years ago, medieval Europe became the first large civilisation not to be run by human muscle power. Thousands and thousands of windmills and waterwheels, backed up by animal power, transformed industry and society radically. It was an industrial revolution entirely powered by renewable energy – something that we can (and do) only dream of today. Wind and water powered mills were in essence the first real factories in human history. They consisted of a building, a power source, machinery and employees, and out of them came a product.

Windmills and waterwheels were not new technologies – both machines appeared already in Antiquity and the ones used in the early Middle Ages were technically no different from those. However, ancient civilisations like the Greeks and the Romans hardly used them, possibly because of religious reasons and because of a large enough reservoir of human slave labour. Water powered mills were – overall – more important and numerous than windmills. This is logical since they are a simpler and more reliable technology; the flow of a river might change according to the seasons, but generally a river always contains water. Moreover, by making use of canals and sluice gates the flow of water could be precisely controlled to provide the speed or load required by the gearwork inside the factory.

The wind, on the other hand, does not always blow. When it does, wind velocity and direction can change at any moment and windmills had no efficient method to control the strength of the wind – at least not in early medieval times. Water powered mills appeared in Europe in large numbers from the end of the eleventh century onwards and only 200 years later almost all available energy in rivers and streams was put to use. However, not all regions were suited for watermills. The reasons could be that they did not have sufficient water resources (like Spain), that they were too flat and their rivers did not have enough flow (like the Netherlands and the downlands of England) or that rivers generally froze during winter (like in Scandinavia, Russia and parts of Germany). In these countries, windmills appeared in the thirteenth century, possibly earlier, and spread fast. Later, also regions that had abundant water resources constructed windmills, to relieve the pressure on rivers and streams.

How Many Windmills?

The number of windmills in early medieval times remains unknown, because the few inventories that could be studied do not distinguish between water and wind powered mills. For instance, we know that there were between 10,000 and 12,000 mills in the UK in 1300, but we do not know how many of them were wind powered (it must have been a minority). We only have are data on individual windmills, which start to appear at the end of the 1200s. In the 1700s and 1800s, when windmill technology really caught on, more accurate inventories appear.

In 1750, there were 6,000 to 8,000 windmills in the Netherlands, in 1850 there were 9,000 of them. For comparison, this is almost 5 times as many as there are wind turbines in the Netherlands today (1,974 turbines as of September 2009). In the UK there were 5,000 to 10,000 windmills in 1820. France had 8,700 windmills (and 37,000 watermills) in 1847. Germany had 18,242 windmills in 1895 (compared to around 18,000 wind turbines today) and Finland had 20,000 windmills in 1900. Portugal, Spain, several Mediterranean islands and many Eastern European and Scandinavian countries had many windmills, too. The total amount of wind powered mills in Europe was estimated to be around 200,000 (at its peak), compared to some 500,000 waterwheels. Windmills were built in the countryside and in cities, and even on the walls of castles and fortifications in order to catch more wind.

Initially, the only applications of windmills were the grinding of grain and (to a lesser extent) the pumping of water and the draining of lowland areas (for which they were connected to a waterwheel working in reverse – the scoopwheel – or to an Archimedean screw. Bread and oats were the staple diet of the Middle Ages (meat, fish and vegetables were only available to the rich) and all that grain had to be crushed or ground. It took one person with a hand mill two hours a day to grind enough flour for an average family. Corn windmills were also used to make Dutch gin and other liquors. The grinding of grain remained the most important use of windmills – as late as 1900, the entire wheat harvest of Northern Europe was ground by windmills in the Netherlands, Denmark and Germany.

Wind Powered Factories

However, around 1600 many new applications of windmills appeared. Windmills were used for hulling barley and rice, grinding malt, pressing olives to olive oil, and pressing coleseed, linseed, rapeseed and hempseed for cooking and lighting. There were also cocoa mills, mustard mills and pepper mills (also used for other spices), even tobacco mills and snuff mills. Besides food production, two other major applications of windmill technology were the production of paper (using ropes and sails from ships as a raw material) and the sawing of wood. Windmills were also crushing chalk (to make cement), grinding mortar, draining mines, ventilating mineshafts (and even a prison), polishing glass and making gunpowder. Textiles were another industry in which wind power came to the rescue: windmills were crushing seeds from flax (to make linen), preparing hemp fibres (to produce ropes and sailcloth), fulling cloth (to create soft wool), making paint and tanning and dying animal skins.

One of the most spectacular developments of industrial wind power technology occurred in the Zaan district, a region situated just above Amsterdam in the Netherlands. Although the area is surrounded by water, the potential of water power was limited because the land is as flat as it can be and so the flow of the rivers is low. The wind, on the other hand, is strong. Many of the applications of windmills described above appeared first (and sometimes only) in the Zaan. It is said that the region was the world’s first industrialised area. From 1600 to 1750, when the Netherlands became an important economical power, around 1,000 windmills were built and operated here. Mills were given names, just like ships.

A vital element of the wind powered industry in the Zaan district was the sawmill. Wood was required to construct houses, sluices, ships and of course more windmills. Hand sawing was a very laborious task and windmills greatly reduced the time needed for the process. With hand sawing, sixty beams or trunks would take 120 working days, with wind power this only took four to five days. The first sawmill (Het juffertje or The missy) was built in the town of Zaandam by Cornelis Corneliszoon in 1596. By 1630, there were 83 sawmills north of Amsterdam, of which 53 were located in the Zaan district. The peak was reached in 1731 when there were 450 sawmills in the Netherlands, 256 of them in the Zaan district. Eventually even the crane of these mills, to haul up the timber, was driven by the sails.

Another early industrial application of wind power in the Zaan district was the production of paper – this was, after all, the era in which the printing press appeared. The first papermaking windmill (De Gans or The Goose) dates from 1605 and by 1740 there were forty of them. In the middle of the seventeenth century, the Dutch paper mill was substantially improved, which enabled it to make whiter paper and make it faster. One remaining example is De Schoolmeester (The Teacher), built in 1692. Wind powered paper mills were rare in other countries, but water powered versions already appeared in the 11th century and became quite common – in England there were 417 of them in 1800. Other remarkable windmills in the Zaan district were snuff and tobacco mills (38 in 1795), oil mills (140 in 1731), barley hulling mills (65 in 1731), dyestuff mills (21 in 1731) and hemp mills (20 in 1731). The Dutch also built hundreds of windmills in the West Indies for crushing sugar cane. Relatively few of the 1,000 surviving windmills in the Netherlands are industrial windmills – drainage and corn mills remained economically viable much longer.

In many other European countries, similar functions were mainly performed by watermills. However, not all activities powered by waterwheels could be powered by sails. The fickleness of the wind made windmills unsuited for processes that required a very steady and reliable power output, like metal making, spinning, tool-sharpening or extracting minerals from mines. In countries where the potential of water power was insufficient, some of these activities were powered by animals, mainly horses. Horses were also used as a backup power in long periods of calm, in order to guarantee delivery. For instance, in the Netherlands in 1850, there were 1,800 windmills for the grinding of corn, but also 1,300 horsemills for the grinding of buckwheat – a grain that required a more steady power source for grinding.

Post Mills and Tower Mills

Early medieval windmills were simple machines, derived from waterwheels. During the following centuries, however, windmills became a very sophisticated technology. Windmills are much more complicated machines than waterwheels because wind velocity and speed change continually. Earlier windmills in Iran and Afghanistan were of the horizontal (vertical-axis) type, and thus did not have to adapt to changes in wind direction. But these machines, which were much less efficient, were never used in Europe. Initially, medieval millwrights solved the problem of varying wind direction by positioning the whole mill on a central spindle so that it could be turned to face the wind. This was the so-called post mill.

Around the 1400s, a second type of windmill appeared, in which only the cap and sails rotated and the body of the mill remained stationary. This was the so-called tower mill, which was later perfected by the Dutch. Tower mills were also the dominant type around the Mediterranean, but these were less efficient machines with very different sails. Because it was stationary, the main body of a tower mill could be constructed from stone or brick, and thus they were more sturdily built. Both types continued to be in use, but many post mills were replaced by tower mills from the 1600s to the 1800s.

These days, wind turbines are turned into the wind automatically by means of electronic equipment. When the wind becomes too strong, the electronics turn the blades out of the wind so they are not blown to smithereens. Medieval millwrights had no microchips and so they had to find another solution. For many centuries, windmills were turned into the wind by mere muscle power. This was done by lifting a large tailpole at the back of the mill (hooked up to the tail ladder in the case of a post mill), moving it to the required position, and fixing it again at one of the twelve anchor posts sunk into the ground in a circle around the mill.

This was not an easy task, because the body of a post mill had to be turned with the weight of all the machinery inside. Some mills were equipped with a winch at the end of the tailpole, riding on a circular track, which made the task a bit easier. The cap of tower mills was turned in a similar fashion, by means of a much longer tailpole – reaching to the ground or to the terrace in the case of a tower mill with a stage. Vent holes were drilled in the sides of the body of the mill – when the wind started blowing through one of these holes, the miller knew that wind direction had changed.

Adjusting the Sails: a Daunting Task

Adapting to variations in wind velocity was even more challenging. The factory machinery inside the mill required a rather precise operating speed. For instance, corn mills worked best at fifty to sixty sail revolutions per minute. Once surpassing 80 sail revolutions per minute the grain would burn. Another risk was that when sails started turning too fast, the windmill could be destroyed. Again, for centuries, the miller had to do this by hand. Basically, there were two ways to adjust to changing wind speeds. Minor differences in wind velocity could be absorbed inside the mill, by increasing or decreasing the load. For instance, in a corn mill, adapting to a higher wind speed could be done by widening the gap between the milling stones and adding more grain. Because the load is increased, the amount of revolutions of the sails remains more or less the same in spite of the higher wind speed.

When the changes in wind speed became too large, however, the miller had no choice but to get out of the mill and adjust the sails. Traditional windmills were not equipped with blades, but with sails – mostly a wooden framework covered with canvas (in colder climates the canvas was generally replaced by slats of wood, which were easier to handle in freezing conditions). Reefing two or even four sails, or reducing sail area were very effective methods to adjust to higher wind speeds, but these must have been daunting tasks in high winds. At least two sails had to be brought within a vertical position and stopped so that the miller, climbing the sail, could take off the cloth. If the brake failed while the miller was in the sail, he would be in for a spectacular ride. Tying and reefing all four sails was also a standard procedure at the beginning and end of each working day.

During the second half of the eighteenth century, several complex but effective techniques were developed that made it possible for a traditional windmill to be left mostly unattended, at least when it concerned changes in wind speed and direction. In 1745, the English blacksmith Edmund Lee invented the self regulating wind machine or winding, a device that automatically adapted the positioning of the windmill to the direction of the wind. It consisted of a fantail (two fantails for larger windmills) and a gearwork. A fantail can be described as an auxiliary windmill that is mounted behind the main sails, at a right angle to them. If the direction of the wind changes, it hits the fantail, turning the mill until the main sails are again perpendicular to the wind.

The fantail is geared down to a travelling wheel in the cap of the tower (in case of a tower mill) or around the building (in case of a post mill). Fantails were later used for wind-powered water pumps in the US, but because these machines were much lighter there was no need for a gearwork to turn them. The winding not only made the handling of the mill much easier, it also augmented the power output. A substantial amount of power can get lost because of slight variations in the wind direction, but the miller did not always have the time (or the will) to turn the windmill following every minor change.

Automatic Control: Spring and Patent Sails

Around the same time as the fantail and winding were invented, mechanisms started to appear that were aimed at automatically adapting the sails to varying wind speeds. This led to the development of the so-called spring-sail in 1772, invented by Scottish millwright Andrew Meikle. On a spring sail, the sailcloth is replaced by dozens of shutters like those of a Venetian blind. Each shutter is controlled by a spring. As the wind increases, it overcomes the force of the spring and the shutter will open, letting the wind through and slowing down the sails. The stronger the wind, the more the shutters will open. When the wind speed decreases, the shutters will be closed by the spring, again forming one uninterrupted surface. All of this results in having sails with a similar rotation speed at any wind velocity.

The problem with spring-sails is that the tension of the springs (which are all connected to each other by means of a long pole) has to be adjusted beforehand depending on the expected wind speed and the power needed. Once set, it is impossible to make adjustments while the sails are turning. This was solved in 1789 by Stephen Hooper, who introduced blinds that could be adjusted with a manual chain from the ground without stopping the mill (roller reefing sails). However, the system was too complicated. The final improvement to self-reefing sails came in 1807 when William Cubit attached counterweights to the adjustment chain of spring sails, making the control of the sails fully automatic without the complexity of the roller reefing method – these were called patent sails.

The only problem left was that patent sails had a lower efficiency than normal sails, and as a result it was common to combine two patent sails with two normal sails as a compromise between handling and efficiency. In 1848, the Frenchman Berton replaced the many small shutters by fewer longitudinal shutters operating according to the same principle, an intriguing method that gave a sturdier construction and a better aerodynamic performance (Berton Sails). Moreover, the system could be adjusted by the miller from inside the cap of the mill. In 1860, Catchpole introduced air brakes, which were a very effective means to automatically slowing down the sails in a gale. Inside the mill, an automatic centrifugal governor replaced the manual adapting of the distance between the milling stones.

As was the case with the fantail, self-reefing sails did not only improve the handling of the windmill, but also the power output. Because there was no longer a need for the miller to stand on the ground to fix or unfurl the sails, the wind shaft could be installed much higher so that the mill could benefit from higher wind speeds (the Dutch had solved this issue before by constructing tower mills where the sails could be reefed from a stage at a higher level).

Iron Gears

Another important improvement was the introduction of cast iron for the manufacture of the gearwork. This happened in 1755, only ten years after the introduction of the winding, by John Smeaton. For centuries, all gears inside the mill were made of wood. This resulted in serious energy losses. Measurements performed by the Dutch in the 1930s, on a drainage windmill constructed in 1648, showed that the mill generated around 40 horsepower at the windshaft but only 15.6 horsepower at the machines – an efficiency of only 39 percent. Almost two thirds of the generated power was lost in the transmission. Drainage mills had a slightly higher efficiency of around 50 percent.

The use of cast-iron (and later iron) did not only improve the efficiency of the gearwork, but also allowed for the construction of larger windmills. The use of wood limited the diameter of the sails to around 30 meters – already common in the 1600s. The maximum length of a stock (more than twice the length of one sail) was around 30 metres (100 feet) because there were no larger trunks available. Only in the second half of the nineteenth century iron stocks came to be used for the sails and for the windshaft.

Innovations Came Too Late

Unfortunately, the many important improvements of windmill technology came too late. Already at the end of the 1700s, around the same time that these innovations appeared, the first corn mill switched from wind power to steam power – and to the black smoke that came with it. Around 1850, steam powered mills became more common and the importance of windmills started to decline. To make things worse, fantails, self-reefing sails and iron stiffening were slow to catch on – in many countries and regions they were never even used.

Berton sails were only applied in France, patent sails were mainly used in England. Although iron stocks allowed for the construction of larger sails, that never happened. The highest tower mill ever constructed was made entirely out of wood. It was standing in the Netherlands and was constructed in 1899 (De Hoop or The Hope in Prinsenhagen, now the city of Breda). It stood 38 metres (125 ft) tall, with sails around 27 metres (88.5 ft) in diameter. The cap and sails were removed in 1929 but the tower is still there.

The two Dutch windmills with the largest sail diameter are standing in the Golden Gate Park in San Francisco, built between 1903 and 1905. The largest one, the Murphy Windmill, stands 29 metres (95 ft) tall with sails 35 metres (114 ft) across. The stocks were cut from one single log – the US had larger trees. But its gearwork is made entirely of cast iron and that shows: the mill pumped up to 150,000 litres (40,000 gallons) of water per day to irrigate the park. The Murphy Mill was replaced by an electrical engine some years later and fell into disrepair.

The decline of the windmill was slow, especially in the Netherlands – the Dutch even preferred windmills with auxiliary steam engines over fully steam powered mills. More than six million wind powered waterpumps (with annular sails) would be built in the United States between the 1850s and the 1930s, but elsewhere few windmills were erected after 1900. The attention shifted to wind turbines generating electricity, and that has remained so ever since.

Innovation in the 1920s and 1930s

In the 1920s and 1930s, however, when windmills had stopped working almost everywhere in Europe, the Dutch started a research program that led to the final development of the classical windmill. In 1923, the Dutch Windmill Society was founded, with the mission to improve the performance of windmills generating mechanical energy. Among the members were famous millwright builders like the Dekker Brothers. The results were spectacular. Through the application of aeronautical principles and the use of sheet metal (basically equipping traditional windmills with sails somewhat similar to the blades of modern wind turbines) the maximum power output of a windmill was doubled from 50 to 100 horsepower at the end of the 1920s. More than 70 windmills were equipped with the new “Dekkerized sails” during the following decade. Moreover, improvements in the gearwork slashed energy losses and allowed for windmills to generate much more power at lower wind speeds.

Tests conducted in 1939 by the Prinsenmolen Committee showed that an improved windmill would start to turn with a wind speed of 3.5 to 4 m/s (7.75 to 9 mph) compared to 5 to 6 m/s (11 to 13.5 mph) for the old design. At 5.5 m/s (12.5 mph) their power was found to be equal to that of a normal mill at 8 m/s (18 mph). This meant that while a traditional windmill could be worked for around 2,671 hours per year in the Netherlands, the new streamlined design could be operated for 4,442 hours per year – more or less doubling the annual energy output. The improved windmill had two advantages; a greater output at a given wind speed, and longer working hours by utilising lighter winds. The gain was especially found in lower wind speeds, because with stronger winds the sails of the improved windmill had to be reefed sooner.

More improvements during the 1930s by Chris van Bussel, Kurt Bilau, G.J. Ten Have, Van Riet, P.L. Fauël, Sabinin and Yurieff led to a windmill, installed in 1940 and demolished in 1960, with up to two and a half times the power output of windmills with traditional sails: 125 horsepower. Next, the Second World War stopped further investigations and after the war, like the rest of the world, the Dutch shifted their attention to the generation of electricity.

Back to Traditional Windmills?

Today, windmills and waterwheels that convert kinetic energy directly into mechanical energy are considered obsolete, and while some have survived, few of them have any commercial function. Wind turbines now turn renewable energy into electricity, which might later be converted back to mechanical energy. Of course it is impossible to operate a flat screen television or a laptop with mechanical energy, but many other processes could in principle still be driven in that old-fashioned way. Grain still has to be ground, wood still has to be sawn, seeds still have to be pressed, but now we use electricity to drive machines that perform the same processes. This electricity can be generated by means of modern wind turbines, or other renewable energy sources, and that is the future that everybody has in mind.

However, there are some reasons that might make it interesting to revert to a direct conversion from kinetic to mechanical energy. For one thing, it is more efficient because the intermediate step of generating electricity causes conversion losses. This means that we have to build less renewable energy plants to get the same work done. Planting a few million high-tech wind turbines, or covering deserts with solar plants sounds attractive, but the most important question is whether there are enough material, energy and financial resources available to make those dreams ever come true. Available data on the reserves of rare resources required for many high-technologies look grim. Windmills that convert kinetic energy directly into mechanical work could be operated with simpler materials.

On a more positive note, traditional windmills could be improved substantially with today’s knowledge and fairly common materials. The gearings and sails could be made of steel or aluminum, which would seriously improve efficiency and also make windmills fireproof. Being made entirely or in large part of wood, many windmills were destroyed by fire. Of course, also the factory machinery inside the mill could be made much more efficient now. Traditional windmills could now be built larger and thus more powerful. To give an indication; in 2005, the Dutch built another traditional windmill, that generates electricity – the Noletmolen in Schiedam. It stands almost 42 metres tall with sails 30 metres across, slightly less than the Murphy Mill in San Francisco. It was built for promotional purposes by a distillery (the town hosts 5 more historical mills built to produce Dutch gin). Although the mill is not really a “mill”, it is built according to a traditional design, but using high-tech materials and sails. The result is a power output of more than 200 horsepower at the windshaft.

Backup power for a traditional windmill could be delivered by an electrical motor instead of horses (or we could just work when the wind blows). There is no doubt that now, 70 years later, we could still seriously improve the Dutch experiments from the 1930s. The results might not look as romantic as a traditional windmill, but very useful. Of course, this is not a plea to eliminate electricity-generating wind turbines or electricity. But, some things might be more efficiently done with direct conversion of kinetic energy to mechanical energy. ←

A Dutch saw mill. National Institute of Standards and Technology, public domain.

A Dutch saw mill. From: Theoretisch en practisch molenboek: voor ingenieurs, aannemers, molenaars en andere bouwkundigen, G. Krook, 1850.

A Dutch saw mill. From: Theoretisch en practisch molenboek: voor ingenieurs, aannemers, molenaars en andere bouwkundigen, G. Krook, 1850.

A Dutch saw mill. From: Theoretisch en practisch molenboek: voor ingenieurs, aannemers, molenaars en andere bouwkundigen, G. Krook, 1850.

A Dutch saw mill. From: Theoretisch en practisch molenboek: voor ingenieurs, aannemers, molenaars en andere bouwkundigen, G. Krook, 1850.

A Dutch saw mill. From: Theoretisch en practisch molenboek: voor ingenieurs, aannemers, molenaars en andere bouwkundigen, G. Krook, 1850.

A post mill.

Windmill with tail pole. Image by Donald Vandenbulcke.

The mechanism of a windmill. Library of Congress, Prints and Photographs Division, NY-67.

A windmill with fantail. Image by Cnyborg (CC BY-SA 3.0).

A windmiller climbs the sail. Image: Brimz (CC BY-SA 3.0).

Windmill in Xanten, Germany. Image: Avda (CC BY-SA 3.0)

Patent sails.

A windmill with spring sails in Poland. Image by Polimerek (CC BY-SA 4.0).

A windmill with roller reefing sails in Ireland. Image by Caroline Hornet (CC BY 2.0).

A windmill with Berton sails in France. Image by Berrucomons (CC BY-SA 3.0).

A “Dekkerized” sail. Image by Rasbak (CC BY-SA 3.0).

A windmill with Bilau blades. Image in the public domain.

References

Hills, Richard L. (1994). Power from Wind: A History of Windmill Technology. New York: Cambridge University Press.

Stokhuyzen, Frederick (1962). Molens [The Dutch Windmill]. London: Merlin Press & Bussum: C.A.J. van Dishoeck.

The Prinsenmolen Committee (1966). Research inspired by the Dutch windmills: An account of an extensive programme of research and development.Wageningen: Veenman.

Dumas, Maurice (1962). Histoire générale des techniques. Paris: Presses Universitaires de France.

s.a. Molendatabase (website, 1999-2019), http://www.molendatabase.nl

(Pictures and descriptions (in Dutch) of windmills in the Netherlands.)

Steele Ball, Robert (1908). Natural sources of power. New York, D. Van Nostrand company

Lintsen, H. W. (1992). Geschiedenis van de techniek in Nederland, de wording van een moderne samenleving 1800-1890. Deel I: Techniek en modernisering. Landbouw en voeding. Zutphen: Walburg Pers.

Wikipedia, The Free Encyclopedia, s. v. “Gevlucht”, http://nl.wikipedia.org/wiki/Gevlucht.

Encyclopedia Britannica, s.v. “History of technology”, https://www.britannica.com/technology/history-of-technology.

Encyclopedia Britannica, s.v. “Energy conversion”, https://www.britannica.com/technology/energy-conversion.

Encyclopedia Britannica, s.v. “Windmills”, https://www.britannica.com/technology/windmill.

McNeil, Ian (1990). An Encyclopedia of the History of Technology. London: Routledge.

Lucas, Adam (2005). Wind, Water, Work: Ancient And Medieval Milling Technology. Leiden: Brill Academic Publishers.

Johnson, Richard W. (1998). Handbook of Fluid Dynamics. Boca Raton, Fla. : CRC Press.

Wolff, Alfred R. (1885). The windmill as prime mover. New York: J. Wiley & sons.

Smeaton, John (1760). An experimental enquiry concerning the natural powers of water and wind to turn mills. London: n.p.

van Natrus, Leendert & Polley, Jacob & van Vuuren, Cornelis (1734). Groot volkomen Moolenboek: of naauwkeurig ontwerp van allerhande. Amsterdam: n.p.

Penterbak modelbouw (website, 2019), http://www.penterbak.nl (pictures).

Industriemolens (website, 2019), http://www.industriemolens.nl (pictures of industrial windmills in the Netherlands).

Hemming, Peter (1936). Windmills in Sussex; a description of the construction and operation of windmills exemplified by up-to-date notes on the still existing windmills in Sussex.. London: The C. W. Daniel Co. Ltd.

Boonenburg, K. (1951). Windmills in Holland.The Hague: Information Office.

Wikipedia, The Free Encyclopedia, s. v. “Windmill sail”, (accessed May 9, 2019), http://en.wikipedia.org/wiki/Windmill_sail.

Amezcua-Ogáyar, Juan M. & Rojas-Sola, José I. (2005). “Origen Y Expansión De Los Molinos De Viento En España”, Interciencia. Vol. 30, Nr. 6, pp. 7-14.

Langdon, John. The windmill: a medieval steam engine?

Basalla, George (1989). The Evolution of Technology. Cambridge: Cambridge University Press.

Hau, Eric (2003). Windkraftanlagen: grundlagen, technik, einsatz, wirtschaftlichkeit. Berlin, Heidelberg: Springer.

European Route of Industrial Heritages (website, 2019), http://www.erih.net/welcome.html.

Berry, Mark. “Windmills of California”, Windmill World (website, 1997). http://www.windmillworld.com/world/california.htm

Puts, Jan (2011). “Noletmolen”, De Nederlandse Molendatabase (website, 1999). http://www.molendatabase.nl/nederland/molen.php?nummer=1280.

Water Powered Cable Trains

Cable trains (or funiculars) are one of the most energy-efficient modes of transport out there.

With cable trains, a large portion of the power required to pull up the ascending car is delivered by the counterweight of the descending car. Many historical systems used this efficiency and took it one step further with systems exclusively powered by water and gravity. Cable trains first appeared within the second half of the 19th century. Many of them have survived and continue to be utilised (mostly in a modernized form) and new systems are being developed. A cable train system is operated on a steep slope with a gradient of up to 55 percent and consists of two passenger cars which are connected by a steel cable. Both cars travel on the same single track, which is undoubled in the middle so that they can pass each other.

Cable trains prove extremely energy efficient because a large share of the power required to pull up the ascending car is delivered by the counterweight of the descending car. Since the system only needs one track and can go straight up a mountain, it also saves a lot of materials and space (some systems use two tracks but follow the same principle). A funicular should not be confused with a cog wheel train – even though many older cable cars applied a similar mechanism, as a braking system and speed governor, not as a traction method.

Water Powered Cable Trains

Originally, cable train systems were even more energy-efficient than they are today. Instead of using an engine to pull the cable, the extra power required to overcome friction and to pull up the ascending car was delivered by filling the water reservoir of the upper car. Before departure, the employee in the upper station was informed of the number of passengers that had entered the ascending car. He then knew exactly how much water the reservoir of the descending car should contain (around 80 litres per passenger).

From the moment the descending car became heavier than the ascending car, the brakes were loosened and both cars were set in motion powered solely by gravity. Once the descending car arrived, its water reservoir was emptied and the process was repeated. Most cable trains using water counterbalanced energy have been replaced by systems that utilise engines. One famous example is the Funiculaire de Montmartre in Paris, France, which was operated by water power from 1900 to 1930 and transported one million passengers per year.

Thankfully, a few water powered cable cars continue to be in service, and have remained so for over a century. The Elevador do Bom Jesus in Braga, Portugal, has been in use since 1882. The Nerobergbahn in Wiesbaden, Germany, has been working since 1888, the Lynton & Lynmouth in North Devon, UK since 1890, and the Funiculaire Neuveville-St.Pierre in Fribourg, Switzerland since 1899).

Perpetuum Mobile

Most water powered cable cars require energy to operate the pump that transports the water up the hill again, so of course, perpetual motion does not exist. There are however some exceptions to this. The 120 metre track in Fribourg, Switzerland, operates without a pump. It makes use of the natural flow of water along the track, more specifically the waste water infrastructure which connects the upper and the lower part of town.

How it works is this: The waste water flows into a reservoir of 100,000 litres. From there it flows in the water tank of the rail car. Around 1,500 litres of water is required to pull up the other car from 60 meters below, and it takes 3 minutes to fill up the tank. After approximately 1.5 minutes, you will have arrived at the ground station. The reservoir is then emptied and the water continues its way downwards through the sewer system. The train route was designed as a (very creative) way to lower the flow of the fountains in the lower part of town.

Gravity

To add to this, in the case of the Lynton & Lynmouth Cliff Railway, no water is pumped from the bottom to fill the tanks at the top station – the water is taken from a nearby river. Moreover, at this track the method is reversed. Both car tanks are full of water, the tank of the bottom car is partially discharged until the bottom car becomes lighter than the top car, and gravity takes its course. The Centre for Alternative Technology built a similar system in 1992 with a lake at the top of the mountain supplying the railway with water.

The main disadvantage of a water-balanced railway (just like any other use of hydro power) is that it cannot be operated when the water freezes over. Bummer. You need a mountain as well, of course. ←

Sewage powered funicular in Fribourg, Switzerland. Image by Bobo11 (CC BY-SA 4.0).

Sewage powered funicular in Fribourg, Switzerland. Image credit: Michel Azéma (www.funimag.com)

Sewage powered funicular in Fribourg, Switzerland. Image credit: Michel Azéma (www.funimag.com)

References

Azéma, Michel (s.d.). Fribourg/ Neuveville-Saint Pierre (website, 1996-2019), http://www.funimag.com/funimag08/FRIBURG2.HTM.

Azéma, Michel (s.d.). Lynton & Lynmouth Cliff Railway (website, 1996-2019),

http://www.funimag.com/funimag19/Lynton04.htm (source & more info).

Get Wired (Again): Trolleybuses and Trolleytrucks

Trolleybuses and trolleytrucks have all the advantages of electric cars – and none of their drawbacks.

A large-scale introduction of electric cars faces technological hurdles and promises to be time-consuming and expensive. Electrifying public transportation and cargo traffic, on the other hand, could be done fast with existing technology for a reasonable price – if we opt for the trolleybus and the trolleytruck. A trolleybus (or trackless trolley) can be defined in two ways; as an electric bus that gets its power from overhead cables, or as a tram (or street car) that drives on rubber tyres. Whichever way you look at it, this combination of bus and tram is the most sustainable (motorised) means of transport that exists in the world today.

Cheap, Fast, Durable

Just like all other electrically powered vehicles (cars, trains, trams) a trolleybus does not produce exhaust fumes, is more efficient than vehicles with a combustion engine, and can drive on renewable energy. The trolleybus, however, has interesting advantages over other electric vehicles. A trolleybus does not need a battery. In this way, it bypasses the weak point of electric cars. Batteries are energy-intensive to produce and limit the mileage of electric cars, which means that the vehicles require an elaborate infrastructure for fast-charging or swapping batteries. Batteries also make electric vehicles heavy and thus less energy efficient than when hooked up to an overhead line – a battery makes up at least one third of the weight of an electric car.

A trolleybus also has advantages compared to other means of electric public transport. Contrary to a train or a tram, a trolleybus does not need a rail infrastructure. This not only results in huge cost and time savings, it also saves a large amount of energy. Installing a trolleybus service is of course more expensive than installing a normal bus line, but that extra cost can be recovered because of lower fuel and maintenance costs. Furthermore, a trolleybus has better braking power than a tram and it is better at climbing hills, since rubber tyres have more grip than steel wheels on steel rails. Trolleybuses are also compatible with bicycles because cyclists cannot get stuck in the tracks. They are more manoeuvrable than trams – a badly parked car will not stop them, because they can diverge from their track for a couple of metres.

Being public transport, trolleybuses of course have the same advantages as trams; they use much less energy and space per passenger than cars. The trolleybus is not only cheap and ecologically sound, it is also fast to implement. There is no need to break up the road, no need to install a charging infrastructure; just attach overhead lines and off you go. This is a political advantage. The announcement and implementation of a system can happen in the same term of service. Because trolleybuses are cheaper than trams, they can also be used on trajectories where a tram would not find sufficient passengers to be cost-effective.

History and Evolution

The first trolleybus got hooked up in 1882; the Elektromote, built by Ernst Werner von Siemens. However, it took almost 20 more years before the first commercial line was installed – in Bielatal, close to Dresden in Germany. During the first half of the twentieth century, and especially since the 1930s, the trolleybus was a success story. Around 1950, there were some 900 trolleybus systems operating worldwide. A large share of these was done away with in the 1960s and 1970s, mostly to the advantage of private cars and diesel buses.

Still, in many cities, the trolleybus never disappeared. Today, 359 cities worldwide still operate trolleybus lines, the number of buses is estimated at 40,000. Most trolley services are located in the former Soviet Union and Eastern Bloc countries – probably another reason for their lousy image. The 1,300 kilometre network in Moscow is the largest in the world. It has 1,500 buses and 100 lines. Minsk, the capital of Belarus, has the second largest network in the world with 1,050 buses and 68 lines. Saint Petersburg has the fourth largest network in the world with 735 buses spread across 41 lines (following Beijing, China, in third place). Ukraine has trolleybuses in more than 25 cities and it boasts the longest trolley line in the world: 85 kilometres from Yalta to Simferopol. The three largest networks in the European Union are Athens, Riga and Bucharest. Other former Eastern Bloc cities with large trolleybus networks are Belgrade, Bratislava, Budapest, Kiev and Sofia.

Switzerland has trolleybuses in 13 cities. Dozens of other cities in Europe have smaller networks. Outside Europe there are trolleybus systems in the US (Boston, Cambridge, Philadelphia, Dayton, San Francisco, Seattle), Canada (Vancouver, Edmonton), Central-America (Mexico City, the largest network in the Americas), Latin-America (Argentina, Brazil, Ecuador, Chile) and Asia (China, North-Korea). Obviously, the technology works, because otherwise it would not have been in service for such a long time in so many places. This cannot be said of electric cars, which all but disappeared in the 1920s.

Hybrid Trolleybuses

Compared to diesel buses, trolleybuses do have a couple of disadvantages. A trolleybus is more manoeuvrable than a tram, but less so than a diesel bus. If the road is being repaired or rebuilt in a street where trolleybuses pass, chances are that the line has to be discontinued temporarily. A diesel bus can easily be rerouted. Similar to trams, trolleybuses also cannot overtake each other. The most important drawback of trolley systems is the need for overhead cables. They are generally regarded as ugly and meet protest. Especially at crossroads the cable network can be dense and hard to ignore. Similar to trams, the “tracks” of trolleybuses have points, but the whole mechanism of these hangs in the air. We adore wireless technology and that is probably the reason why trolleybuses are regarded as a ridiculous and inferior technology, a relic from the past.

Hybrid trolleybuses provide an answer to most of these disadvantages. By equipping trolleybuses with a battery or an auxiliary diesel motor, the bus can also cover a part of the route without depending on the overhead cables. Most trolleybuses built since 1990 are equipped with at least a small battery or diesel motor for some limited manoeuvring. This can save the installation of overhead cables, especially at turning points and in sheds, where normally a complicated infrastructure is needed to manoeuvre the buses. It can also help to get round road works. On some lines (like in Boston and Philadelphia) hybrid trolley services exist. The bus then covers part of the route on electricity delivered by the overhead cables, while another part is covered by means of a (larger) battery or a diesel engine. In this way some drawbacks of batteries and diesel engines are introduced, but these disadvantages are limited when compared to electric cars or diesel buses. Hybrid buses might be a way to spare some parts of a city of overhead lines.

New Trolleybus Lines

Although some cities have recently decided to stop their (modest) trolley services (Ghent in Belgium, Innsbruck in Austria, Marseille in France and Edmonton in Canada), there are many more cities that have recently expanded or modernised their network, re-introduced trolleybuses, or introduced them for the first time. In France, the trolley lines in Limoges, Saint-Étienne and Lyon (the largest network in France) have recently been expanded and renewed. One line in Nancy (abolished in 1998) will be restored in 2010. In Athens the full fleet of 350 vehicles has been renewed. In Italy trolleybuses have been reintroduced in Rome in 2005 (only one line) and new systems are coming in Lecce, Avellino en Pescara. The system in Bari will be reopened. A dozen other Italian cities have never abolished their trolley services and do not have any intention of doing so.

Castellón de la Plana, a city in Spain, reintroduced trolleybuses in 2007, and the service was expanded in 2008. In Salzburg (the largest network in Austria with 80 buses and 7 routes) the service was recently expanded. A new system is planned in Leeds in the United Kingdom, which would be the first reintroduction of trolleybuses in the UK in 30 years. Vancouver in Canada renewed its buses in 2007 and 2008, Wellington in New Zealand did the same. Even Ethiopia announced a trolleybus system in 2008.

El Trole

The most spectacular progress is made in South-America. This has everything to do with El Trole, the trolleybus network in Quito, the capital of Ecuador with 1.6 million inhabitants. The already impressive network, built in 1995, was

expanded in 2000 and 2008. On a part of the main line (with a length of 19 kilometres) the trolleybuses make use of exclusive lanes, completely separated from other traffic. During peak hours, there is a bus every 50 to 90 seconds (because of the high frequency, there are no schedules). El Trole transports 262,000 passengers each day. Five other trolleybus lines connect to it, as well as several other bus lines (including Ecovía, a line similar to El Trole but using diesel buses). The average distance between stops is 400 metres.

The system in Quito is being copied in Mérida (Venezuela), the first part of that line opened in 2007. Other cities in Latin America study the possibility of installing a similar infrastructure, and the Quito system was also the inspiration for the proposals in England and Scotland. By choosing the cheaper trolleybus over tram or metro, Quito could develop a much larger network in a shorter time. The capital investment of the 19 kilometre line was less than 60 million dollar – hardly sufficient to build 4 kilometres of tram line, or about 1 kilometre of metro line. Lower investment costs also mean lower ticket fares, and thus more passengers.

Furthermore, the system is well devised. There is only one ticket fare, payment happens in the station, not on the bus. Stops are comfortable and built to get fast in and out of the bus, there are very good connections with other lines (sometimes via the same stop), and thanks to the exclusive lanes and (at some crossroads) automatically controlled traffic lights the system is extremely reliable. In Quito, the bus always arrives on time. Unfortunately, El Trole has become a victim of its own success. The Ecuadorian government now plans to convert (the larger part of) the main line to a much more expensive light rail line, arguing that the network is saturated. A protest group consisting of citizens and traffic engineers opposes the 500-750 million dollar plan and demands that the money is used to extend of the trolleyline instead:

The same investment required to build the 20 to 30 km of light rail would build 250 km of exclusive lanes for trolleybuses including vehicles, stations and terminals. Quito’s system of rapid urban mass transport would be complete, providing efficient service, with money left over for construction of bikeways throughout the city, for recovery and integration of public spaces, widening of sidewalks, planting trees and providing urban furniture, building walkways between bus stops and passenger destinations, and other projects to complement the system, in such a way to be able to have a city with an optimal public transport service, placing us in the lead among cities with the best public transport in the world.

Whatever the outcome in Quito will be, the many advantages of a trolleybus line should not lead to the conclusion that light rail systems are evil or unnecessary. When passenger capacity grows, it can make sense to convert the busiest trolleylines to light rail systems. The income of a popular trolleyline might serve to finance the succeeding rail network. Another compromise are rail-guided trolleys. These vehicles have rubber tyres but are guided by one rail in the middle, which makes it possible to use longer vehicles.

Trolleytrucks

Trolley systems can also be used for the transport of goods. Trolleytrucks are a lesser known technology but have an equally long history. Initially, they were as popular as trolleybuses, transporting goods between factories and train stations. Especially the German engineer Max Schiemann put together some remarkable examples in the beginning of the 20th century. The technology never really took off, though. Trolleytrucks are still sporadically used in Russia and Ukraine, and in the mining industry. However, in the latter case, the electric engine does not replace the diesel engine, but merely assists it. Another historical example is the Valtellina Dam Project in Italy. These two lines with a total length of 80 kilometres were built in 1936 and remained in service until 1962. Twenty trolleytrucks transported concrete, sand and other construction materials to build two large dams. Today there are no cities that plan a trolleytruck system, but the German city of Dresden does have a Cargo Tram.

Trolleytrucks and trolleybuses are also put forward as a solution in the 2008 book Transport Revolutions: moving people and freight without oil. Authors Richard Gilbert and Anthony Perl propose a plan that would include 500 billion tonne-kilometres of cargo moved by trolleylorry in the US by 2025. Trolleytrucks would replace trucks, and complement cargo trains.

All too often we are blind for the costs of high-tech. If we cannot afford a technology, it is of not much use. Low-tech options that have been proven to work, can deliver much better results for a bargain. The technology to completely electrify land based transportation has been available for over a hundred years. If we want to, we can do the switchover in just a few years time. Let’s start with public transport and cargo traffic, and then let’s see what to do with cars – if we still need them. Trolleycars, even though theoretically possible, are not a practical option. ←

The first trolleybus, 1882. Image in the public domain.

A trolleybus in England, 1966. Image: Alan Murray-Rust (CC BY-SA 2.0).

A trolleybus in Minsk. Image by Romancieslik (CC BY-SA 3.0).

A trolleybus in Lyon, France. Image by Florian Fèvre (CC BY-SA 4.0).

Trolleybuses in Luzern, Switzerland. Image by Re 460 (CC BY-SA 3.0).

A small trolleytruck in Barcelona, 1956. Image: Dewi Williams.

The Valentina trolley system (1938-1962). A total of twenty trolley trucks were used to carry concrete, sand and equipment for the construction of two dams in northern Italy.

The Valentina trolley system (1938-1962). A total of twenty trolley trucks were used to carry concrete, sand and equipment for the construction of two dams in northern Italy.

Experimental trolley truck in Ukraine, 1954.

A cargo tram in Dresden, Germany. Image by kaffeeeinstein (CC BY-SA 2.0).

References

Allen Morrison, El Trole / Los Trolebuses de /The Trolleybus System of Quito, Ecuador (website, 2009). http://www.tramz.com/ec/q/b1.html.

(A map of the trolleybus line in 2009: http://www.tramz.com/ec/q/bm.html).

Rosenthal, Elisabeth (2009). “With Bogotá’s System as Model, Buses May Aid Climate Battle in Poor Cities”, The New York Times, July 9, 2009, p. A12.

Sterratt, David. Scottish Electric Transit (website, 2007), http://www.scottishelectrictransit.org.uk/.

SkyscraperCity (website, 2000), http://www.skyscrapercity.com/showthread.php?p=39000502#post39000502.

Municipality of the Metropolitan District of Quito, Operating Unit of the Trolleybus (UOST), Municipal Transportation Bus Company (EMT), Transportation Planning and Management Unit (UPGT) (2003). The Electric Trolleybus System of Quito, Ecuador. Accessible through https://web.archive.org/web/20090918085949/http://www.iges.or.jp/APEIS/RISPO/inventory/db/pdf/0044.pdf.

Quito Update: LRT Conversion Plans Advance, Stir Controversy-1, a www.publictransit.us special webreport (website, 2009). Accessible through https://web.archive.org/web/20120229161306/http://www.publictransit.us/ptlibrary/eltroleupdate1.htm.

TRAQ, Tren Ligero de Quito (2007). Nuevo Sistema de Transporte Urbano Masivo de Quito. Accessible through https://web.archive.org/web/20090918085946/http://www.innovar-uio.com/web/galerias/traq/TRAQ-book.pdf.

Quito para todos (website, 2008). Accessible through https://web.archive.org/web/20101127020325/http://www.quito
paratodos.org/index.php?option=com_content&view= article&id=32:no-al-tren-
ligero-traq&catid=14:documentos&Itemid=24.

Wikipedia, The Free Encyclopedia, s. v. “Oberleitungsbus”, (accessed June 7, 2019), http://de.wikipedia.org/wiki/Oberleitungsbus.

Wikipedia, The Free Encyclopedia, s. v. “Bombardier Guided Light Transit”, (accessed June 9, 2019), http://en.wikipedia.org/wiki/Bombardier_Guided_Light_Transit.

Hutnyak Consulting. “1938-1962: Valtellina Dam Project”, Trolley History (website, 2001), http://hutnyak.com/Trolley/trolleyhistory.html#Valtellina.

The Railfaneurope.net Picture Gallery (website, 2015), http://www.railfaneurope.net/pix/de/trams/Dresden/CarGoTram/pix.html

City Cargo (website, 2007). Accessible through https://web.archive.org/web/20070523225911/http://www.citycargo.nl/over.htm

Christian Dumitru, Trolley Truck (website, 2008). Accessible through https://web.archive.org/web/20120218100113/http://trolleytruck.eu/.

Chester, Michael V. & Arpad Horvath (2009). “Environmental assessment of passenger transportation should include infrastructure and supply chains”, Environmental Research Letters, Vol. 4, No. 2.

“Amount of space required to transport the same amount of passangers by car, bus or bicycle: Poster in city of Münster Planning Office, August 2001” van het “Press-Office City of Münster, Germany”.

The longest trolleybus line in the world! (website, 2003). http://www.blacksea-crimea.com/Places/trolleybuses.html.

The Electric Tbus Group, World Trolleybus systems (website, 2006). http://www.tbus.org.uk/systems.htm.

The Electric Tbus Group, Why the Trolleybus? (website, 2006). http://www.tbus.org.uk/article.htm. http://www.tbus.org.uk/leeds.htm

El Trole, a www.publictransit.us special webreport (website, 2005), accessible through https://web.archive.org/web/20090813065634/http://www.publictransit.us/ptlibrary/eltrole.htm.

Electric Road Trains

German engineer Max Schiemann was among the first engineers to develop a commercial trolleybus system for passengers at the turn of the 20th century. He also created some unique cargo systems.

1. Hafenschleppbahn in Altona (1912-1950)

The most succesfull (and most remarkable) trolleytruck network designed and constructed by Schiemann was the Hafenschleppbahn in Altona, today an area in Hamburg. The road from the port to the town was so steep that horses had severe difficulty climbing it. Trolleytruck technology came to the rescue, but the electric trucks on the one kilometre long track (up and down) did not replace the horses. The trucks were used as an assisting power source. The trolleytruck pushed or pulled one or more horse cars, while other wagons (handcarts included) were also attached to the convoy.

This hybrid system combining electricity with animal and human power started operation in 1912 and remained in service until 1950. Each day, around 200 wagons were pulled or pushed up the hill, each convoy transporting 5 to 7 tonnes of cargo. In the first ten months of its existence, the road trains took more than 22,000 wagons up the hill. Total electricity consumption during that period was 30,878 kilowatt-hours.

The maximum speed of the trolleytrucks was 10 kilometres per hour while climbing the hill and 30 kilometres per hour on flat terrain. The average speed of the convoy was 5 to 8 kilometres per hour and the trip up the hill took 8 minutes, coupling and uncoupling included. In total six trucks were used, several of them at the same time (two trucks crossing posed no problem since the one coming down was not connected to the overhead line). Fees were collected during the trip. The service was initially exploited by the Gesellschaft für gleislose Bahnen Max Schiemann & Co. From 1922, it was run by the town of Altona, and later by the city of Hamburg.

2. Bielatal Bahn (1901-1904) & Industriebahn Wurzen (1905-1928)

The first system built by Schiemann and his Gesellschaft für gleislose Bahnen Max Schiemann & Co. was the Bielatalbahn, a 2.8 kilometre long track in Sachsen. It carried both passengers and cargo (mainly for a paper factory). The track operated only from 1901 to 1904, but the infrastructure was reused to build (part of) a new line close to Leipzig: the Industriebahn Wurzen, an exclusive cargo line which was in operation from 1905 until 1928.

It was 3.46 kilometres long (4.23 kilometres up to 1914, when an extra track was in use). The cargo system consisted of 2 trolleytrucks, 10 wagons for coal transport (each with a capacity of 6 tons) and 27 wagons for flour transport (each with a capacity of 5 tons). Each truck had a power output of 25 HP and could pull a maximum of 3 wagons with a total weight of 15 tonnes. The speed of the road train was 6 kilometres per hour when loaded and 8 kilometres per hour when unloaded. The trolleytrucks were initially equipped with wood and iron wheels with spokes, only later to be replaced by rubber tyres. The same trucks were used for the full 23 years, accidents did not occur.

The line was constructed to transport flour from a flour mill to the cargo train station. An extra track carried coal from a mine to the station, but was closed when the mine shut down in 1914. On average, 300 tons of cargo was transported each day. Planned extensions to a wallpaper factory and a felt factory were never realised. Since the production facilities of Schiemann were located in the same town, the track was also used to test vehicles and convoys for other lines. Allegedly, the owner of the flour mill also had a small private passenger vehicle for use on the line.

3. Kalkbahn Grevenbrücker (1903-1907)

The first trolleyline built exclusively for cargo (the Kalkbahn) was installed in Grevenbrück, a village in the present-day municipality of Lennestadt in Nordrhein-Westfalen. The 1.5 kilometre trajectory served to transport limestone from a quarry (opened in 1902) to the train station. The route went straight through the town and crossed an old bridge. The line opened in 1903 and was closed in 1907, when the quarry was relocated. The service was operated by the mining company itself, the Grevenbrücker Kalkwerke.

About 20 convoys passed each day, at a speed of 6 kilometres per hour (loaded) or 7 to 8 kilometres an hour (unloaded). The trucks could pull 3 to 4 wagons (each with a capacity of 5 to 6 tonnes) in good weather conditions, and 2 wagons when there was ice or snow. In winter, the trolleytrucks were equipped with snow tyres. For the same reason, the wagons on the first Schiemann system (the Bielatalbahn described above) were equipped with skates. The trolleytruck was also used to pull a rolling mill for road building. The Kalkbahn was built in just 3 months. Financial savings were about 33 percent compared to the same trajectory by horse cart.

The town of Grevenbüch also had a second line, the Veischedetal Bahn, which was in operation from 1904 to 1916. Until 1907 it transported both passengers and goods (mainly tobacco to some cigar factories), after that date it carried only passengers and mail. The route was 8 kilometres long and the vehicles attained a speed of 18 km/h. Both trolley lines came together at the train station.

4. Other Schiemann Trolley Lines

Max Schieman built 12 lines in total: several passenger trolley lines as well as some more routes that were used to transport both passengers and cargo. The Gleislose Bahn Blankenese-Marienhöhe had a length of 3 kilometres and carried passengers between the train station and the town. It was in operation from 1911 to 1915. The passenger line Gleislose Bahn Ahrweiler was in operation from 1906 to 1917 and had a length of 5.5 kilometres. The 4.5 kilometres long Gleislose Bahn Monheim-Langenfeld transported both goods (5,000 tonnes per year), passengers and mail. It was in operation from 1904 to 1908 and was the only line that was discontinued because of technical problems – the trucks were too heavy and damaged the road.

Contemporaries of Schiemann, building or experimenting with trolleytruck systems, were Werner von Siemens, Lombard Und Guérin (France), Carl Stoll, Charles Nithard (France), E.Cantono (Italy), Hans-Ludwig Stoll and Lloyd Köhler. World War I slowed down the further development of trolley systems, and it was only in the 1930s that the technology really took off. Only for passengers, though, since cargo systems never became widespread. ←

Cargo system powered by electricity, human and animal power, 1912-1950, Hamburg, Germany.

Electric road train, 1901-1928, Sachsen, Germany.

References

Ludger, K. “Historische Bahn: Die „Gleislose Bahn” Blankenese – Marienhöhe” (2008), Drehscheibe Online (website, 1996), http://www.drehscheibe-foren.de/foren/read.php?17,3950299,3950299#msg-3950299.

Wikipedia, The Free Encyclopedia, s. v. “Gleislose Bielathal-Motorbahn mit elektrischer Oberleitung”, (accessed June 9, 2019), http://de.wikipedia.org/wiki/Bielatalbahn_%28Oberleitungsbus%29.

Ludger, K. “Historische Bahn: Die Industriebahn Wurzen” (2008), Drehscheibe Online (website, 1996), http://www.drehscheibe-foren.de/foren/read.php?17,3957677.

Ludger, K. “Historische Bahn: Die Transportbahn
der Grevenbrücker Kalkwerke” (2008),
Drehscheibe Online (website, 1996),
http://www.drehscheibe-foren.de/foren/read.php?17,3926640.

Ludger, K. “Historische Bahn: Die Obuszeit im Ahrtal” (2008), Drehscheibe Online (website, 1996), http://www.drehscheibe-foren.de/foren/read.php?17,3922308.

Wikipedia, The Free Encyclopedia, s. v. “Gleislose Bahn Monheim–Langenfeld”, (accessed June 9, 2019), http://de.wikipedia.org/wiki/Gleislose_Bahn_Monheim%E2%80%93Langenfeld.

The Monster Footprint of Digital Technology

The embodied energy of a memory chip alone exceeds the power consumption of a laptop during its life expectancy of three years.

When we talk about power consumption, all attention goes to the electricity use of a device or a machine while in operation. A 30 watt laptop is considered more efficient than a 300 watt refrigerator. This kind of comparisons does not make much sense if you don’t also consider the energy that was required to manufacture the devices you compare. This is especially true for high-tech products, which are produced by means of extremely resource-intensive manufacturing processes.

More Gadgets

The energy consumption of electronic devices is skyrocketing, as was recently reported by the International Energy Association (Gadgets and gigawatts, 2009). According to the research paper, the electricity consumption of computers, cell phones, flat screen TV’s, iPods and other gadgets will double by 2022 and triple by 2030. This comes down to the need for an additional 280 gigawatts of power generation capacity. An earlier report from the British Energy Saving Trust (The ampere strikes back, 2007) came to similar conclusions. There are multiple reasons for the growing energy consumption of electronic equipment; more and more people can buy gadgets, more and more gadgets appear, and existing gadgets use more and more energy (in spite of more energy efficient technology).

While these reports are in themselves reason for concern, they hugely underestimate the energy use of electronic equipment. To start with, electricity consumption does not equal energy consumption. In the US, utility stations have an average efficiency of about 35 percent. If a laptop is said to consume 60 watt-hours of electricity, it consumes almost three times as much energy (around 180 watt-hour, or 648 kilojoules). So, let’s start by multiplying all figures by 3 and we get a more realistic image of the energy consumption of our electronic equipment. Another thing that is too easily forgotten, is the energy use of the infrastructure that supports many technologies; most notably the mobile phone network and the internet (which consists of server farms, routers, switches, optical equipment and the like).

Embodied Energy

Most important, however, is the energy required to manufacture all this electronic equipment (both network and, especially, consumer appliances). The energy used to produce electronic gadgets is considerably higher than the energy used during their operation. For most of the 20th century, this was different; manufacturing methods were not so energy-intensive. An old fashioned car uses many times more energy during its lifetime (burning gasoline) than during its manufacture. The same goes for a refrigerator or the typical incandescent light bulb: the energy required to manufacture the product pales into insignificance when compared to the energy used during its operation.

Advanced digital technology has turned this relationship upside down. A handful of microchips can have as much embodied energy as a car. And since digital technology has brought about a plethora of new products, and has also infiltrated almost all existing products, this change has vast consequences. Present-day cars and since long existing analogue devices are now full of microprocessors. Semiconductors (which form the energy-intensive basis of microchips) have also found their applications in ecotech products like solar panels and LEDs.

While it is fairly easy to obtain figures regarding the energy consumption of electronic devices during the use phase (you can measure it yourself using a power meter), it is surprisingly hard to obtain reliable and up-to-date figures on the energy consumed during the production phase. Especially when it concerns fast-evolving technologies. A life cycle analysis of high-tech products is complex and can take many years, due to the large amount of parts, materials and processing techniques involved.

In the meantime, products and processing technologies keep evolving, with the result that most life cycle analyses are simply outdated when they are published. For more recent and emerging technologies, life cycle analyses simply do not exist. Try looking for a research paper that calculates the embodied energy of a Light Emitting Diode (LED), a lithium-ion battery or any device full of electronics meant to save energy: you won’t find it.

Embodied Energy of a Computer

The most up-to-date life cycle analysis of a computer dates from 2004 and concerns a machine from 1990. It concluded that while the ratio of fossil fuel use to product weight is 2 to 1 for most manufactured products (you need 2 kilograms of fuel for 1 kilogram of product), the ratio is 12 to 1 for a computer (you need 12 kilograms of fuel for 1 kilogram of computer). Considering an average life expectancy of 3 years, this means that the total energy use of a computer is dominated by production (83% or 7,329 megajoule) as opposed to operation (17%). Similar figures were obtained for mobile phones.

While the 1990 computer was a desktop machine with a CRT-monitor, many of today’s computers are laptops with an LCD-screen. At first sight, this seems to indicate that the embodied energy of today’s machines is lower than that of the 1990 machine, because much less material (plastics, metals, glass) is needed. But it is not the plastic, the metal and the glass that makes computers so energy instensive to produce. It’s the tiny microchips, and present-day computers have more of them, not less.

The energy needed to manufacture microchips is disproportional to their size. MIT-researcher Timothy Gutowski compared the material and energy intensity of conventional manufacturing techniques with those used in semiconductor and in nanomaterial production (a technology that is being developed for use in all kinds of products including electronics, solar panels, batteries and LEDs). As an example of more conventional manufacturing methods, Gutowski calculated the energy requirements of machining, injection molding and casting. All these techniques are still used intensively today, but they were developed almost 100 years ago. Injection molding is used for the manufacture of plastic components, casting is used for the manufacture of metal components, and machining is a material removing process that involves the cutting of metals (used both for creating and finishing products).

While there are significant differences between configurations, all these manufacturing methods require between one and ten megajoule of electricity per kilogram of material. This corresponds to 278 to 2,780 watt-hour of electricity per kilogram of material. Manufacturing a one kilogram plastic or metal part thus requires as much electricity as operating a flat screen television for one to ten hours (if we assume that the part only undergoes one manufacturing operation).

The energy requirements of semiconductor and nanomaterial manufacturing techniques are much higher than that: up to six orders of magnitude (that’s ten raised to the sixth power) above those of conventional manufacturing processes. This comes down to between 1,000 and 100,000 megajoules per kilogram of material, compared to one to ten megajoules for conventional manufacturing techniques. Manufacturing one kilogram of electronics or nanomaterials thus requires between 280 kilowatt-hours and 28 megawatt-hours of electricity; enough to power a flat screen television continuously for 41 days to 114 years. These data do not include facility air handling and environmental conditioning, which for semiconductors can be substantial.

Embodied Energy of a Microchip

The energy consumption of semiconductor manufacturing techniques corresponds with a life cycle analysis of a “typical” 2 gram microchip performed in 2002. Again, this concerns a 32 MB RAM memory chip – not really cutting edge technology today. But the results are nevertheless significant: to produce the 2 gram microchip, 1.6 kilograms of fuel were needed. That means you need 800 kilograms of fuel to produce one kilogram of microchips, compared to 12 kilograms of fuel to produce one kilogram of computer.

If we take the energy density of crude oil (45 MJ/kg), this comes down to 72 megajoules (or 20,000 watt-hour) to produce a 2 gram microchip. Converted to a one kilogram microchip this comes down to 3.3 megawatt-hours of electricity (or 36,000 MJ), well within the range of the 280 kilowatt-hours (1,000MJ) and 28 megawatt-hours (100,000 MJ) calculated above. Also, the International Technology Roadmap for Semiconductors (2007 edition), gives a figure of 1.9 kilowatt-hours per square centimetre of microchip, so 20 kilowatt-hours per 2 gram, square centimetre computerchip seems to be a reasonable estimate.

How Many Microchips in a Computer?

A gadget or a computer does not contain one kilogram of semiconductors – far from that. But, we don’t need a kilogram of microchips to ensure that the manufacturing phase will largely outweigh the usage phase. The embodied energy of the memory chip alone already exceeds the energy consumption of a laptop during its life expectancy of 3 years. Today’s personal computers have a RAM-memory of 0.5 to 2 gigabyte modules that typically consist of 18 to 36 two-gram-microchips (as the ones described above). This equates to 1,296 to 2,595 megajoules of embodied energy for the computer memory alone, or 360,000 to 720,000 watt-hour. Enough to power a 30 watt laptop non-stop for 500 to 1,000 days.

Microprocessors (Central Processing Units or CPU’s, the “brains” of all digital devices) are more advanced than memory chips and thus contain at least as much embodied energy. Unfortunately, no life cycle analysis of a microprocessor has been published. Certain is that modern computers contain ever more of them. One trend in recent years is the introduction of “multicore processors” and “multi-CPU systems”. Personal computers can now contain two, three or four microprocessors. Servers, game consoles and embedded systems can have many more. Each of these cores is capable of handling its own task independently of the others. This makes it possible to run several CPU-intensive processes (like running a virus scan, searching folders or burning a DVD) all at the same time, without a hitch. But with every extra chip (or chip surface) comes more embodied energy.

Another trend is the rise of the Graphics Processing Unit or GPU. This is a specialised processor that offloads 3D graphics rendering from the microprocessor. The GPU is indispensable to play modern videogames, but it is also needed because of the ever higher graphical requirements of operating systems. GPU’s do not only raise the energy consumption of a computer while in use (GPU’s can consume more energy than current CPU’s), but they also stand for more embodied energy. A GPU is very memory-intensive and thus also increases the need for more RAM-chips.

Manufacturing Process

Why are microchips so energy-intensive to manufacture? One of the reasons becomes clear when you literally zoom in on the technology. A microchip is small, but the amount of detail is fabulous. A microprocessor the size of a fingernail can now contain up to two billion transistors – each transistor less than 0.00007 millimetres wide. Magnify this circuit and it becomes a structure as complex as a sprawling metropolitan city.

The mass of materials embedded in the product might be small, but it takes a lot of processing (and thus machine energy use) to lay down a complex and detailed circuit like that. While the electricity requirements of machines used for semiconductor manufacturing are similar to those used for older processes like injection molding, the difference lies in the process rate: an injection molding machine can process up to 100 kilograms of material per hour, while semiconductor manufacturing machines only process materials in the order of grams or milligrams per hour.

Another reason why digital technology is so energy-intensive to manufacture is the need for extremely effective air filters and air circulation systems (which is not included in the figures above). When you build infinitesimal structures like that, a speck of dust would destroy the circuit. For the same reason, the manufacture of microchips requires the purest silicon (Electronic Grade Silicon or EGS, provided by the energy-intensive CVD-process).

Every 18 months the amount of transistors on a microchip doubles (Moore’s law). On one hand, this means that less silicon is needed for a certain amount of processing power or memory. On the other hand, when transistors become smaller, you need even more effective air filtration and purer silicon. Since the structure also becomes more complex, you need more processing steps.

Nanotechnology operates on an even smaller scale than micro-electronics, but its energy requirements are comparable. Carbon nanofiber production, which is based on many of the same techniques used by semiconductor manufacturing, requires 760 to 3,000 MJ of electricity per kilogram of material, while carbon nanotubes and single-walled nanotubes manufacturing requires a hefty 20,000 to 50,000 MJ per kilogram. The manufacture of nanotubes is thus as energy-intensive as the manufacture of microchips (36,000 MJ). Many of the large-scale applications proposed for nanotubes will simply not be possible because of energy requirements.

Recycling is No Solution

Encouraging recycling is often proposed as a way to lower the embodied energy of products. Unfortunately, this does not work for micro-electronics (or nanomaterials). In the case of conventional manufacturing methods, the energy requirements of the manufacturing process (one to ten MJ per kilogram) are small compared to the energy required to produce the materials themselves. For instance, producing 1 kilogram of plastic out of crude oil requires 62 to 108 MJ of energy, while a typical mix of virgin and recycled aluminum requires 219 MJ. To make a fair comparison, you have to multiply the energy requirement of the manufacturing process by three (one megajoule of electricity requires three megajoules of energy) but even then (with three to thirty MJ/kg) conventional manufacturing processes appear to be quite benign compared to materials extraction and primary processing (in the order of 100 MJ/kg).

In the case of semiconductor manufacturing, this relation is reversed. While it takes 230 to 235 MJ of energy to produce one kilogram of silicon (already quite high compared to many other materials), chemical vapour deposition (an important step in the semiconductor manufacturing process) requires about 1,000 MJ of electricity and thus 3,000 MJ of energy per kilogram. That is ten times more than the energy consumption of material extraction and primary processing. In the case of conventional manufacturing techniques, the use of recycled material is an effective way to lower overall energy use during production. In the case of semiconductors, it is not. Recycling is not a solution for energy consumption if all your energy use is concentrated in the manufacturing process itself.

This does not mean that the manufacture of microchips does not require materials. However, these concern auxiliary materials which are not incorporated into the product. For example, the embodied energy of the input cleaning gases in the CVD process (not included in the figures above) is more than four orders of magnitude greater than that of the product output. Furthermore, these gases have to be treated to reduce their reactivity and possible attendant pollution. Gutowski writes: “If this is done using point of use combustion with methane, the embodied energy of the methane alone can exceed the electricity input”.

The Benefits of Digital Technology

Microchips also have positive effects on the environment, by making other activities and processes more efficient. This is the subject of a publication by the Climate Group, an initiative of more than fifty of the world’s largest companies. The report (Smart 2020 – enabling the low carbon economy in the information age, 2008) confirms the findings of other studies regarding the electricity use of electronic equipment, but also calculates the benefits. According to Smart 2020, the emissions from Information and Communications Technology (including the energy use of data centres, which the IEA report does not include) will rise from 0.5 Gt CO2-equivalents in 2002 to 1.4 GtCO2 equivalents in 2020, assuming that the sector will continue to make the “impressive advances in energy efficiency that it has done previously”. By enabling energy efficiencies in other sectors, however, ICT could deliver carbon savings 5 times larger: 7.8 Gt CO2-equivalents in 2020.

These benefits are smart grids (2.03 Gt), smart buildings (1.86 Gt), smart motor systems (970 Mt), dematerialisation and substitution (500 Mt) and smart logistics (225 Mt). One of the first tasks of ICT will be to monitor energy consumption and emissions across the economy in real time, providing the data needed to optimise for energy efficiency. The report concludes:

The scale of emission reductions that could be enabled by the smart integration of ICT into new ways of operating living, working, learning and travelling, makes the sector a key player in the fight against climate change, despite its own growing footprint.

But even if we assume that all these savings will materialise (the report acknowledges that this will not be an easy task), this conclusion does not take into account the energy needed to manufacture all this equipment. If we assume the share of manufacture to be 80 percent of total energy consumption by ICT (following the only life cycle analysis of a computer we have), then the 1.4 Gt in 2020 in reality should be 7 Gt – almost as much as the 7.8 Gt that will be saved by ICT. No environmental benefit would appear and the energy savings realised by digital technology, would merely absorb its own growing footprint.

Digital Technology is a Product of Cheap Energy

The research of Timothy Gutowski shows that the historical trend is toward more and more energy intensive processes. At the same time, energy resources are declining. Gutowski writes:

This phenomenon has been enabled by stable and declining material and energy prices over this period. The seemingly extravagant use of materials and energy resources by many newer manufacturing processes is alarming and needs to be addressed alongside claims of improved sustainability from products manufactured by these means.

Production techniques for semiconductors and nanomaterials can and will become more efficient, by lowering the energy requirements of the equipment or by raising the operating process rate. For instance, the International Technology Roadmap for Semiconductors (ITRS), an initiative of the largest chip manufacturers worldwide, aims to lower energy consumption per square centimetre of microchip from 1.9 kWh today to 1.6 kWh in 2012, 1.35 kWh in 2015, 1.20 kWh in 2018 and 1.10 kWh in 2022.

But as these figures show, improving efficiency has its limits. The gains will become smaller over time, and improving efficiency alone will never bridge the gap with conventional manufacturing techniques. Power-hungry production methods are inherent to digital technology as we know it. The ITRS-report warns that: “Limitations on sources of energy could potentially limit the industry’s ability to expand existing facilities or build new ones”.

Gutowski writes:

It should be pointed out that there is also a need for completely rethinking each of these processes and exploring alternative, and probably non-vapour-phase processes.

Technological Obsolescence

The ecological footprint of digital technology described above is far from complete. This article focuses exclusively on energy use and does not take into account the toxicity of manufacturing processes and the use of water resources, both of which are also several orders of magnitude higher in the case of both semiconductors and nanomaterials. To give an idea: most water used in semiconductor manufacturing is ultrapure water (UPW), which requires large additional quantities of chemicals. For many of these issues, the industry recognizes that there are no solutions. There are also the problems of waste and conflict.

Last, but not least: the energy-intensive nature of digital technology is not due only to energy-intensive manufacturing processes. Equally as important is the extremely short lifecycle of most gadgets. If digital products would last a lifetime (or at least a decade), embodied energy would not be such an issue. Most computers and other electronic devices are replaced only after a couple of years, while they are still perfectly workable devices. Addressing technological obsolescence would be the most powerful approach to lower the ecological footprint of digital technology. ←

Die shot of Texas Instruments TMS9981 microprocessor. Image by Paul Rautakorpi (CC BY 3.0), CPU Museum.

Die shot of Monolithic Memories Inc. (MMI) 6701D 4-Bit Expandable Bipolar Microcontroller. Image by Paul Rautakorpi (CC BY 3.0), CPU Museum.

References

Environmentally Benign Manufacturing (EBM) (website, s.d.). “Academic articles & popular press”, http://web.mit.edu/ebm/www/publications.htm. (More information on manufacturing methods)

Gutowski, Timothy et al. (2009). “Thermodynamic Analysis of Resources Used in Manufacturing Processes”, Environmental Science & Technology, Vol. 43, No. 5, pp. 1584-1590.

Additional information to accompany Figure 4 in the paper above: http://pubs.acs.org/doi/suppl/
10.1021/es8016655/suppl_file/es8016655_si_001.pdf

Organisation for Economic Co-operation and Development (2009). Gadgets and Gigawatts: Policies for Energy Efficient Electronics. OECD Publishing.

Energy Saving Trust (EST) (2007). The ampere strikes back. How consumer electronics
are taking over the world. Londen: EST.

“News: The 1.7 kg Microchip”, IT & Environment
Initiave (website, 2002). Accessible through https://web.archive.org/web/20060211083555/http://www.it-environment.org/1point7kg%20microchip.html.

International Technology Roadmap for Semiconductors (website, 2007). Accessible through https://web.archive.org/web/20080422073202/http://www.itrs.net/Links/2007ITRS/Home2007.htm.

Wikipedia, The Free Encyclopedia, s. v. “The Climate Group”, (accessed June 9, 2019),
http://en.wikipedia.org/wiki/Climate_Group#Members.

Smart 2020 (website, 2008). Accessible through https://web.archive.org/web/20110203061327/http://www.smart2020.org/.

International Technology Roadmap for Semiconductors (2007). “Environment, Safety, and Health”, ITRS report. Accessible through http://www.itrs.net/Links/2007ITRS/2007_Chapters/2007_ESH.pdf.

Iglesias, Matthew. “The ‘Congo’ Chip”, Yglesias, Think Progress (website, 2009). Accessible through https://web.archive.org/web/20090723194143/http://yglesias.thinkprogress.org/archives/2009/06/the-congo-chip.php.

Cargo Ships, Then and Now

Time for a new age of sail.

On an early afternoon last month, the Eugen Maersk (the world’s longest ocean freighter at 1,300 feet) has left Rotterdam, the Netherlands, on the tail end of a journey from Shanghai. But the giant freighter is cruising at 10 knots, well shy of her 26-knot top speed. At about half speed, fuel consumption drops to 100-150 tons of fuel a day from 350 tons, saving as much as $5,000 an hour [1].

The German Preussen, the largest sailing ship ever built, was launched in 1902 and travelled mainly between Hamburg (Germany) and Iquique (Chile). It was rammed by a large steam vessel in 1910. A one way trip between Germany and Chile took the cargo vessel between 58 and 79 days. The best average speed over a one way trip was 13.7 knots. The lowest average speed was 10 knots [2] [3].

One giant container ship can emit almost the same amount of cancer and asthma-causing chemicals as 50 million cars, study finds [4]. Time for a new age of sail. ←

The German Preussen, the largest sailing ship ever built.

References

[1]: Miller, John W. (2009). “Shippers Taking It Slow in Bad Times. As Volume Drops, Moeller-Maersk Scales Back on Fuel, Napkins and Canal Passages”, The Wall Street Journal, April 8, 2009.

[2]: “Fünfmastvollschiff ‘Preußen’”, Werften &
Stadtgeschichte Bremershavens (website, 2001). Accessible through https://web.archive.org/web/20110721041403/http://werften.fischtown.de/archiv/preussen1.htm. Refers to 1) Horst Hamecher: Fünfmast-Vollschiff Preussen- Königin der See, Verlag Hamecher Kassel 1993, 2) Peter Klingbeil: Die Flying P-Liner- Die Segelschiffe der Reederei F. Laeisz, 1998 Deutsches Schiffahrtsmuseum, Bremerhaven, und Ernst Kabel Verlag GmbH, Hamburg.

[3]: Bruzelius, Lars (2000). “Preussen”, Bruzelius.info (website, 1996). http://www.bruzelius.info/Nautica/Ships/Fivemast_ships/Preussen%281902%29.html. “In a thorough analysis of sailing ship performance conducted by Captain M. Prager at the Deutschen Seewarte and published in Annalen der Hydrographie in 1905 under the title Die Fahrtgeschwindigkeit der Segelschiffe auf großen Reisen, figures based on the first four voyages of the Preussen were presented.”

[4]: Vidal, John (2009).“Health risks of shipping pollution have been ‘underestimated’”, The Guardian, April 9, 2009.

Moonlight Towers: Light Pollution in the 1800s

At the end of the 19th century, many towns and cities were lit up by powerful electrical lamps placed on towers up to 90 metres (300 feet) high.

The arc lamp – the first electric light and the predecessor of Edison’s incandescent light bulb – was extremely bright and much more energy efficient than other lighting technologies from those times. The lamps were too strong for indoor use, but they were regarded as the future of municipal lighting. Especially in the United States, many cities and towns were illuminated as if they were immense sports stadiums.

The arc light (or electric candle) was invented and demonstrated by Sir Humphry Davy at the very beginning of the nineteenth century in England. Davy, who can be considered the true founder of electric lighting, discovered that a blinding white light was produced by hooking up two charcoal rods to a battery, and bringing them very close together.

In an incandescent light bulb (which was developed only seventy years later) an electric current is transferred over a filament, but in the case of an arc lamp this happens through the air instead. If two electrified carbon rods touch each other, some of the carbon vaporizes. By further moving the rods just a little bit apart, the current flows through the vaporizing carbon and spans the air gap with an arc of intense light.

An electric candle typically produced a light of 1,500 to 6,000 candlepower, which corresponds to the output of 11 to 43 modern 100-watt incandescent light bulbs. The temperature in the arc could rise to 4,000 °C (more than 7,000 °F), the highest temperature that man achieved until the arrival of the atomic bomb.

Candles, Oil and Gas Lamps

The discovery of the arc light was a spectacular feat, because the light it produced was incomparably stronger than anything else available at that time: candles, oil lamps and – appearing around the same time – open flame gas lights, which produced only ten to twenty candlepower. It was obvious that the powerful light of an arc lamp was absolutely unsuitable for use in a room. As a way of lighting up streets and large interior spaces, however, the technology sounded very promising.

Large buildings, like theatres, were sometimes lit by hundreds or even thousands of candles. It took an awful lot of work to install, to light and to replace all those candles, not to mention the toxic smoke, the smell, the heat, the built-up of soot and the risk of fire resulting from this.

Oil lamps had similar drawbacks, and the recent open flame gas lamps were only a modest improvement – the only advantages being that they were a little bit stronger and cleaner and only had to be ignited once. Streets were lit by oil or open flame gas lamps (or not at all). Every street lamp had to be lit individually every night, and extinguished every morning.

Lamps, But No Electricity

In spite of the poor alternatives, it took more than 70 years before the arc lamp resulted in practical lighting devices on a large scale. The problem was not so much the lamp itself, but the power source. The only sources of electricity during the first half of the 19th century were inefficient batteries, which made the use of arc lamps very impractical and excessively expensive.

In the 1840s and 1850s, there were some public demonstrations with arc lights and a few early limited applications (notably in lighthouses, theatres and on large construction sites), but it was only with the arrival of useful electric generators (dynamos) at the end of the 1870s, that the arc lamp took off.

Around that time, the most important disadvantage of the arc lamp was also solved. The carbon rods were consumed while the lamp was burning, which meant that the lamp had to be regulated by hand almost continuously to keep the distance between the rods constant.

This was more or less resolved in the 1840s by self-regulating mechanisms, but it was the invention of the Yablochkov arc lamp in 1876 that resolved the issue completely. The rods were placed parallel to each other, which eliminated the need for complex mechanisms. That made the arc lamp much more reliable.

Twenty Times More Energy Efficient

At the end of the 1870s, gas light had conquered the streets of many cities, to a lesser degree still supported by earlier oil lamps. But arc lamps were brighter, cheaper and safer. Around the same period the first practical incandescent light bulbs appeared, but they were not much competition either.

Early incandescents only produced around twelve candlepower and were twenty times less energy efficient than arc lamps (it is interesting to note that nineteenth century arc lamps are still more energy efficient than todays incandescents, and that early twentieth century arc lamps can even compete with today’s compact fluorescents – but this is comparing apples to oranges since arc lights were not suited for use indoors).

What followed was a true boom of arc lighting. Hundreds of thousands of arc lights were installed, mainly on streets and squares but also on markets, in harbours, railway stations, public buildings, department stores, exhibition halls, hotels, theatres, office buildings, castles, monuments, museums and libraries. Paris set the ball running in 1877, with 54 street lights on the Avenue de l’Opéra and 80 lamps in the Grand Magasins du Louvre. London and other European cities followed in 1878, and in 1879 the first arc lights were installed in the United States.

The US quickly became the leader of electric arc lighting. In 1884 there were already more than 90,000 arc lamps lighting the night sky in the US, and that number rose to 235,000 in 1890, when virtually every US city was using arc lighting, more than 400,000 in 1902 and almost 700,000 in 1907. But it was not just in numbers that the US outstripped Europe and Great Britain.

Moonlight Towers

While European cities placed electric candles on posts, like we do today with street lights, the Americans had the idea of lighting entire cities and villages by means of a grid of towers that stood up to ninety metres (300 feet) tall. These structures, sometimes resembling oversized oil derricks, were equipped with four to six arc lights of 2,000 to 6,000 candle power each. Most of them burnt all night and all year (except at full moon) although some cities turned the lights off around midnight.

The first arc light tower was erected in San José, California, in December 1881 [1]. It stood 237 feet tall and was supplied with six arc lights boasting a total light production of 24,000 candlepower (a replica half the height has been built on the same spot, the original tower collapsed in 1915 following a storm) [2]. The idea of placing arc lights on towers did not go unnoticed in Europe. It is believed that the Eiffel Tower in Paris, finished in 1889 and also equipped with powerful arc lights, was inspired by the first San José tower – the American city even sued Paris (in 1989!), unsuccessfully [1].

During the 1880s and 1890s, dozens of American cities built an infrastructure of arc light towers on their territory. Placing arc lights on high towers made sense. One of the main disadvantages of electric candles was their labour intensive operation. The carbon rods had to be replaced every one or two hours. That would make arc lights as cumbersome as candles, gas lights or oil lamps, were it not for the fact that they were so much brighter.

By grouping them on towers, this carbon trimming could be done with much less man power than was needed for other systems (including arc lights placed on poles or hung at intersections). Moonlight towers were also the most energy efficient way of lighting a whole city, because a minimal amount of lamps was needed, so that everything taken together the lighting tower system was the cheapest available method to light a complete city.

The tower system also had the advantage of safety. Witness this report from the New York Times (1907):

Joseph Gooden was instantly killed by an electric shock today while he was attempting to light a cigar from an arc lamp in the street. With several companions he was returning from a dance when, in a spirit of bravado, he lowered one of the big electric street lamps and put his cigar against one of the carbons. He received a shock of 2,000 volts [3].

Detroit as a Shining Example

In most American cities the lighting tower infrastructure was combined with arc lamps placed on poles or hung at intersections, and complemented with gas or and oil lamps, or incandescents. Detroit was the only large city in the US (and in the world) lighted wholly and exclusively by the tower system. Detroit placed 122 towers with a height of 100 to 180 feet, lighting 21 square miles of the city. All towers were installed in the 1880s and remained in use up to the end of the 1910s.

The lighting infrastructure in Detroit was regarded as the future of street lighting, and stood as an example for the rest of the US. The following excerpts are taken from Municipal lighting, a practical guide for city lighting that was published in 1888:

The press of the country has uniformly conceded Detroit to be the best-lighted city in the world. All its streets, yards, backyards and grounds are illuminated as effectually as by the full moon at the zenith. The blending of light from the mass of towers serves to prevent dense shadows. Detroit has about 230,000 inhabitants, and has a dense business section of about one square mile. This section has about 20 towers, which average 1,000 to 1,200 feet apart. The belt immediately contiguous, embracing the closely-built and densely shaded residence section has its towers about 2,000 feet apart. Beyond this the spaces widen to 2,500 feet apart, and in the suburbs they are spaced about 2,500 to 3,000 feet apart.

The last gas estimate for the 7.5 square miles lighted was $ 104,300. The amount paid the past year for lighting 21 square miles by the tower system was about $ 112,000. The tower lights are burned from dusk to daylight every night in the year. The same service from 2,600 pole lights would amount to $ 332,150 per year.

Lighting by the tower system is assuming great prominence, and merits the calm and thoughtful consideration of all interested in the subject of public lighting. It is the only system thus far presented which affords a thoroughly practical illumination of all spaces at a figure below the cost of gas or naphtha, as the latter is usually employed for quite inadequately lighting the streets alone.

Guidelines

The success in Detroit led to a detailed set of guidelines, to be followed by other American cities. How many towers are needed? The book explains in detail:

Towns of 3,000 to 6,000 inhabitants, occupying, say, a square mile of space, may be lighted in every quarter by seven towers, one at the center and six at the angles of a hexagon, the towers being 2,000 feet apart. So, also, illumination may be had by five towers, there being one at the center and four at the angles of a square, the towers being 2,000 feet from the middle tower, and where greater economy is desirable there might be four towers, one at the center and one at each of the angles of a triangle and about 2,000 feet from the center tower. From 100,000 to 200,000 inhabitants: 100 to 150 towers. More than 200,000 inhabitants: 150 to 300 towers (162).

The towers should, as far as practicable, be arranged in a triangular system. In all cases it is recommended that the towers should have at least four lights of 2,000 candlepower each. The central towers might have six lights (161).

Dark Corners

The guidebook acknowledges that towers are in many cases best complemented by other arc lights, preferably placed at intersections:

It will rarely happen that the tower system can be used exclusively in any place. There will always be dark corners that cannot be reached except at great expense, and in such localities a single low light is used with good effect (99).

Placing lamps over the intersection of streets is the best method when low arc lighting is desired. By placing a lamp over the intersection of a street, you place the lamp where it can do the most possible good, as it can light the streets equally in four directions a distance of about 400 feet radius of the lamp (152).

Disadvantages of the Tower System

Not everybody was convinced of the tower system, however. In one chapter of the book, local authorities are asked for their experiences with the moonlight towers. As well as many positive (and sometimes ecstatic) comments, some responses were very negative. In Ogden, Utah, for instance:

The tower system of electric lighting was tried here several years ago, and discarded as being a complete failure. It is a bad system for street lighting, being impossible to erect a tower high enough to throw the lights in the streets uniformly. One side of the streets will be shaded by the buildings, which produces an intense darkness (when contrasted by the light on the opposite side), which is very disagreeable. Our city is now lighted by electric lamps placed in the center of the street (164).

Others had a more balanced opinion. Council Bluffs, Iowa:

The light is certainly an improvement on the gas lamps. The light is about the same that would be expected from a half moon. You can notice the removal of a brick, stone or plank on the sidewalk, as you walk along. Still, there are people who complain that the light is not sufficiently bright (164).

Saginaw, Michigan:

I should never use towers in thickly settled parts, where streets are all built up on both sides with high buildings: even three story buildings appear to destroy the effect of light sideways. Towers do well in wide streets, and will range 1,500 to 2,000 feet each side (166).

Utica, New York:

The towers are used mainly in the outskirts and thinly settled districts. There they are a perfect success. In the heart of the city they are a failure (167).

The Decline of Moonlight Towers

The criticism of some local authorities in 1888 already showed what would eventually be the death-sentence of the lighting tower system: the arrival of ever higher buildings. The first decades of the twentieth century were the era of the skyscraper, and those buildings were incompatible with moonlight towers. Lighting towers that were higher than 150 feet, like the first one in San José, proved ineffective [1]. From the guidebook:

The advantages of the tower system are only realized when the lamps are placed high enough above the trees and buildings, that they may radiate their light without obstructions near the lamps. The lamps should not be at so great an elevation as that their light will be dissipated in the air before reaching the ground. In the matter of proper height, 150 feet is the most satisfactory. Increasing the height impairs the illumination near the foot and does not perceptibly increase the total lighted area, while diminishing its height diminishes the illuminated area and affords unnecessary brilliance at the base (99).

Life Expectancy

Improvements in arc lamp design were another reason for the decline of the tower system. In the 1890s the carbon consumption of the rods was slowed down considerably by enclosing the lamp in a gas tube, which increased the life expectancy of the carbon sticks fivefold – enough to make the rods last all night.

That made it possible to maintain arc lights in streets and on intersections with more or less the same amount of man power than what was needed for the towers. More lamps were required in that case, which made the system slightly more expensive, but the distribution of light was much better.

Later arc lights could burn for 100 to 150 hours (four to six days) without replacing the rods. Also, the irritating sound production of arc light, another disadvantage of low arc lighting, was largely solved in the 1890s.

Incandescents & LEDs

Another reason for the decline of the moonlight towers was the fact that alternative electric systems, notably the incandescents of Edison, were improved substantially. Again, the advantage was a better distribution of light, which justified slightly higher costs. This was already acknowledged in 1888:

The advantage of the greater candle power of the arc light is offset by the much better distribution of the incandescent, so that all things considered the incandescent is not at such disadvantage as would appear from the mere comparison of the candle power of the different lights (101).

The merit of Edison was that he succeeded in dividing the intense light of the arc lamp in smaller units, so that electric lighting eventually became suited for use inside buildings, even in small rooms. The current development of LED lights faces the opposite challenge as that of early electric lighting: to create a bright white light that is strong enough to compete with incandescents and fluorescents.

Film Projectors and Search Lights

Most lighting towers were demolished during the first two decades of the twentieth century (quite a few also collapsed during storms and tornadoes, or were destroyed by bus drivers misjudging a turn). The only ones that remain today are 17 of originally 31 towers in Austin, Texas – they are still working, albeit not by means of arc lights [4]. Lighting towers are still used today, of course, during events and on traffic junctions and construction sites for instance, but they too make use of more advanced lamps.

Arc lights lasted longer than arc light towers – in London they were still found on the streets in the 1950s. They also found new applications, notably as film projectors and searchlights. Carbon arc searchlights arrived on the market in 1915 and thousands of them – much more powerful than those used for city lighting – were applied in World War II during military operations. In the 1920s, arc lights were marketed as family health products as a substitute for sunlight.

Compact Fluorescents

Even today, the technology still lives on in a more sophisticated form. Most street lamps and followspots in use today, and even fluorescent compact bulbs and neon lights, are descendants of the electric candle [5]. Another important technology that has developed out of arc lighting, is welding. This explains why it is not advised to build an arc light yourself (which is a fairly easy thing to do) because staring at the arc from nearby can damage your eyes. ←

Moonlight tower in New York.

Moonlight tower in New Orleans.

Arc lighting at an intersection in Detroit.

Lighting candles in large buildings took a lot of work.

Concept of an inversed arc light.

Battery powered arc lighting.

Climbing a moonlight tower.

A searchlight.

References

[1]: Carlson, Eric. “San José Electric Light Tower 1885-1915”, Soft Underbelly of San José (website, 2006). http://www.sanjose.com/underbelly/unbelly/Sanjose/Tower/tower1.html.

[2]: “Electric Light Tower”, History San José (website, 2004). Accessible through https://web.archive.org/web/20110725175105/http://www.historysanjose.org/visiting_hsj/buildings/history_park/light_tower.html.

[3]: “Arc light kills a smoker”, New York Times, May 1, 1907, p. 18.

[4]: Popik, Barry (2008). “Moonlight Towers & Moonlight City”, The Big Apple (website), July 5, 2008. http://www.barrypopik.com/index.php/new_york_city/entry/moonlight_towers_moonlight_city_austin_nickname/.

[5]: Goodman, Marty (1997), “A Brief History of Bicycle Lighting Technology”, Harris Cyclery (website, 2019). http://www.sheldonbrown.com/marty_light_hist.html. Whipple, Fred H. (1888). Municipal lighting. Detroit, Michigan: Free Press print.

More information and illustrations

Beauchamp, K. G. & Kenneth George Beauchamp (1997). Exhibiting Electricity. Stevenage: IET.

Vries, Leonard de (1979). De bliksem getemd: het fascinerende verhaal van 100 jaar elektrische gloeilamp. Bussum: Gooise Uitgeverij.

Shiman, Daniel R. (1993). “Explaining the Collapse of the British Electrical Supply Industry in the 1880s: Gas versus Electric Lighting Prices”. Business and Economic History, Vol. 22, No. 1, pp. 318-327.

Bodanis, David & Del Roy (2007). Electric universe: the shocking true story of electricity. Santa Ana, California: Books on Tape.

Tiles as a Substitute for Steel: The Art of the Timbrel Vault

The craftsmanship associated with timbrel vaulting has long vanished, but the achievements are still with us today.

Brick, stone and concrete are materials strong in compression (you can pile them up almost indefinitely), but weak in tension (if the structural breadth increases, the material has to be supported by many columns or it collapses).

Nowadays, this problem is solved by steel structures or the use of steel reinforced concrete – the tensile strength of steel is significantly more than that of bricks, stone or plain concrete. Pre World War II, the weak tensile strength of brick was compensated for by superior craftsmanship.

The timbrel vault allowed for structures that today no architect would dare to build without steel reinforcements. The technique was cheap, fast, ecological and durable.

A Roof of Tiles

The method of timbrel vaulting was developed in the fourteenth century around the Mediterranean, although its precise origins are unknown. The timbrel vault is also known as a masonry vault, Catalan vault, tiled vault, laminated vault, flat vault and layered vault (derived from Spanish, French, Italian and Catalonian descriptions). Timbrel vaulting differs substantially from the Roman method of arch building, which relies on gravity. A Roman vault consists of a single layer of thick, wedge-shaped stones.

The timbrel vault does not rely on gravity but on the adhesion of several layers of overlapping tiles which are woven together with fast-setting mortar. If just one layer of thin tiles was used, the structure would collapse, but adding two or three layers makes the resulting laminated shell almost as strong as reinforced concrete. The result defies common sense, because a timbrel vault is very thin compared to a Roman vault, while at the same time it is capable of bearing much higher loads. This of course enables wider spans and gentler curves.

The timbrel vault was perfected in Catalonia, the north-eastern region of Spain. There already were some notable medieval examples, like the Santa Maria del Mar and the Santa Maria del Pi, both churches in Barcelona, and the Catedral de Girona (the widest gothic nave in Europe). At the end of 19th and the beginning of the 20th century, the timbrel vault was rediscovered by the Catalonian architects of the Modernisme movement. Some striking examples are the crypt of the Colonia Guell, which Antoni Gaudí designed in a very low-tech fashion by hanging ropes and weights from the ceiling (the building has now suffered a disastrous restoration), the Aymerich Amat i Jover in Terrassa, a textile factory built by Lluís Moncunill i Parellada, or the Celler Cooperatiu de Pinell de Brai by Cèsar Martinell.

Timbrel Vaults in the US

Most masterpieces of catalan vaulting, however, are in the United States. The method was previously unknown in the Americas, until a family by the name of Guastavinos imported it. Rafael Guastavino, born in Valencia in 1842, improved the centuries-old technique and renamed it cohesive construction. He substituted bricks with thin tiles and the traditional mortar with rapidly hardening Portland cement, which enabled him to build vaults three to five times wider than the typical size of traditional timbrel arching.

Early in his career, around 1880, Guastavino immigrated to the US. There, he and his successors collaborated for more than half a century with architects on the construction of more than 1,000 buildings and structures, many of them renowned monuments today. Nearly 400 of them are located in New York. The Guastavinos made masonry floors, ceilings, vaults, domes and stairs. Their accomplishments were fairly unknown to the general public as they were working as contractors and not as architects.

Some examples of the Guastavinos’ work are the Boston Public Library, the ceiling of the Oyster Bar in Grand Central Terminal, the reception hall of Ellis Island, Carnegie Hall, the US Supreme Court Building, the Nebraska State Capitol, the Queensboro bridge, the US Army War College in Washington, and the Cathedral of St. John the Divine (which has the largest Guastavino dome ever built). Rafael Guastavino and his son (also named Rafael) were granted more than twenty patents and by 1891 the company had offices in New York, Boston, Providence, Milwaukee and Chicago. In 1900 they opened their own factory to manufacture the tiles.

Economical and Fast

The popularity of the timbrel vault was not restricted to its aesthetic appeal. It was simply a very fast and economical method, for two reasons. Firstly, and logically, much less building material was required. Secondly, there was no need for wooden scaffolding. Building a Roman vault demands large amounts of wood, as every arch is required to be supported by a wooden centering for a long period after initial construction. The masonry vault, on the other hand, is self-supporting apart from some temporarily required, light shiftable formwork at the beginning of the job. While constructing a timbrel vault, workers simply stood on the work of the day before (which was two to four inches thick). These savings in both building materials and construction equipment meant that the Guastavinos could offer lower prices than their competitors.

Cohesive construction also made buildings fire-proof (an example of this is the Santa Maria del Mar in Barcelona, which burned for 11 days during the Spanish Civil War, without collapsing or too much damage). There have been some major city fires during the 19th century (like the great Chicago fire in 1871), and the Guastavinos aptly saw the marketing potential: they soon renamed themselves the Guastavino Fireproof Construction Company. There were more advantages to the construction. The floors, ceilings, arches and stairs were sound-insulating and resistant to floods, dampness and the lodgement of pests such as rats and roaches.

Convincing the Public

Cohesive construction also proved to be very durable. During the restoration of Ellis Island in the 1980s, only 17 of almost 29,000 tiles had to be replaced. And of course, several churches are living proof of the achievements of timbrel vaulting in the Middle Ages. The Guastavinos initially had a hard time convincing the public that their ultra-thin and ultra-light arches were strong and safe. To persuade their buyers, the technique was demonstrated in public. In many ways, timbrel vaulting offered similar properties to reinforced concrete, but without the use of steel. It was achieved without computers or engineering calculations, relying instead on intuition and practice.

According to Rafael Guastavino, the masonry vault would become the main construction material of the future. He proved to be wrong. The Guastavinos firm closed in 1962, twelve years after his son died. Rising labour costs and the arrival of steel and concrete building methods rendered the technique virtually obsolete. Still, two later examples deserve attention. One was the Uruguayan architect Eladio Dieste, who applied the timbrel vault to modern buildings (also including steel reinforcements, which made it possible to build to wider breadths). Most notable, and most relevant, are Cuba’s art schools, an unfinished project that was commenced from 1961 to 1965. The ambitious plan forsaw a national complex of art schools. As building materials were scarce, and labour was plentiful, timbrel vaulting was applied. The knowledge was delivered by a former mason of Antoni Gaudí.

Relevance Today

Scarcity of materials is still an issue in Cuba, and it is increasingly becoming an issue for the whole world. Masonry vaults may just come in handy again, one day. Recently there has been more research on the structural behavior of this construction system and some people, for instance at the MIT, also try to revive the technique by practice, which has resulted in several do-it-yourself timbrel vaults. MIT and the Boston Public Library plan to organise an exhibition on the Guastavinos in 2009. ←

Interior of the Aymerich Amat i Jover, a former textile factory in Terrassa, Spain. Image by Enfo (CC BY-SA 3.0).

Timbrel vaulted roof of the Aymerich Amat i Jover, a former textile factory in Terrassa, Spain. (CC BY-SA 2.5).

The Celler Cooperatiu de Pinell de Brai, Spain. Image by Tomàs (CC BY-SA 2.0).

Drawing from Guastavino’s patent application.

Drawing from Guastavino’s patent application.

Drawing of a staircase built with catalan vaulting. From Guastavino’s patent application.

Ceiling of the registry room, Ellis Island, New York. Image by Rich Lemonie (CC BY-SA 4.0).

Ceiling of the registry room, Ellis Island, New York. Image by Rich Lemonie (CC BY-SA 4.0).

Original interior of the Oyster Bar in Grand Central Terminal, New York (1910-1920). Library of Congress.

Spiral staircase of the Saint John the Divine Cathedral. Image by Gstarr310 (CC BY-SA 4.0)

Constructing timbrel vaults.

Constructing timbrel vaults.

To persuade potential buyers that ultra-light arches were strong and safe, the technique was demonstrated in public.

School of Ballet, part of Cuba’s National Art Schools. Image by Duende Thumb (CC BY-SA 3.0).

References

Guastavino (website, s.d.). Accessible through https://web.archive.org/web/20130310135700/http://www.guastavino.net/ : documenting the works of the Guastavino Company in the Boston area (MIT). The site also hosts the patents and essays of Rafael Guastavino and his son.

Atamturktur, Sezer H. (2006). Structural Assessment of Guastavino Domes (Master’s thesis), The Pennsylvania State University. Accessible through https://web.archive.org/web/20090307214543/http://www.atamturktur.com/publications/structural-assessment-of-
guastavino-domes/table-of-contents/files/
fileinnercontentproxy.2008-12-
14.9452639418.

Ramage, Michael H. (2004) “Building a Catalan vault”. MIT. Accessible through http://web.mit.edu/cron/Backup/project/guastavino/www/resources/writings/ramage_text.pdf.

Claveria, Josep M. Huertas (s.d.). “Modernisme, between Love and Hate”, Ruta del Modernisme (website). Accessible through http://www.rutadelmodernisme.com/default.aspxidioma=en&contenido=body_amoriodien.htm.

Uhart, Pedro (s.d.). “Colonia Guëll”, Gaudi Designer (website). Accessible through http://www.gaudidesigner.com/es/colonia-guell.html.

Uhart, Pedro (2011). “The Guëll Crypt – the disastrous restoration of a Gaudi masterpiece”, Gaudi Designer (website), January 19, 2011. Accessible through http://www.gaudidesigner.com/uk/index.html.

Mroszczyk, Lisa J. (2004). Rafael Guastavino and the Boston Public Library (Bachelor’s thesis), MIT. Accessible through https://dspace.mit.edu/handle/1721.1/85831 (a well documented project).

“Exhibition to Span Guastavinos’ Vaulted Career”, Columbia University Record, April 26, 1996, Vol. 21, No. 25.

Wikipedia, The Free Encyclopedia, s. v. “Eladio Dieste”, (accessed July 14, 2019), http://en.wikipedia.org/wiki/Eladio_Dieste.

Wikipedia, The Free Encyclopedia, s. v. “Catedral del vi”, (accessed July 14, 2019), http://ca.wikipedia.org/wiki/Catedral_del_vi.

Cullighan, Ryan (2008). “Cuba’s national art schools”, What’s that on your pants – Humane Thesis (website), February 15, 2008. Accessible through http://humanthesis.blogspot.com/2008/02/cubas-national-art-schools.html.

A Steam Powered Submarine: The Ictíneo

Narcís Monturiol successfully resolved the two basic obstacles presented to submarine inventors: air supply and mechanical power.

Few Victorian inventions have the grace and charm of the Ictíneo, the series of two wooden submarines built by Narcís Monturiol i Estarrol in the second half of the nineteenth century. Unlike some of the better known early submarines from his contemporaries in Germany, France and the United States, the Catalan inventor managed to build submarines that operated flawlessly. The Ictíneo II was the first combustion engine driven submarine ever, pioneering concepts that were only rivalled in the 1940s. Sadly, both submarines were eventually scrapped and Monturiol died penniless and forgotten.

Fish

Monturiol’s Ictíneo (derived from the Greek words for fish and for ship) was launched in 1859 in Barcelona harbour to instant success. Monturiol, who possessed no scientific education, became a local hero. The submarine, made of olive wood supported with oak rings and sheathed in two-millimetre thick copper, measured only 23 feet (7 meters) in length and offered hardly enough space for the captain and the four man crew who powered the ship by cranking.

Despite it’s low-tech appearance, the Ictíneo was a marvel of sophisticated technology, decades ahead of its time. The vessel had a double hull – a spherical inner shell that resisted the water pressure, and an outer fish-like shell that protected the submarine and was used for steerage and hydrodynamics. Between both hulls were four ballast tanks, controlled from within the cabin by valves letting in water or forcing in air. During driving, pitch was controlled by a weight which could be moved along a rail. This micromanagement of buoyancy allowed the Ictíneo to remain at extremely precise depths – a feat which other submarines at that time could not achieve.

Lit by a candle

Monturiol was a man who had safety in mind. Apart from the protective hull, weights could be dropped immediately to surface quickly in case of an emergency. The glass ports on the side, the top and the nose were designed enabling water pressure to push them inside the hull, rendering leaks virtually impossible. The interior of the submarine was lit by a candle, using up precious oxygen although serving as an integral indicator when oxygen began to run low. Monturiol demonstrated his submarine 59 times, without any adverse incident. The machine could stay submerged for two hours and dive up to a depth of twenty meters.

Monturiol was not the first to develop a submarine. The Dutchman Cornelius Jacobszoon Drebbel built some remarkable vessels between 1620 and 1624 based on the unexecuted plans of the 16th century Englishman William Bourne. Essentially, the vessel was an underwater rowing boat enclosed by a leather covered wooden frame. His final model which had six oars, could carry sixteen passengers and stay submerged for three hours, travelling five kilometres down the Thames at a depth of five meters. Robert Fulton, an American living in France at the time, designed the successful Nautilus, which began testing in the Seine in 1800. It could stay submerged for five hours by use of compressed air. The German inventor Wilhem Bauer launched his Brandtaucher in 1850 and his Seeteufel in 1856 (both of which sank). The American inventor Horace Hunley launched H.L.Hunley, the first submarine to sink an enemy warship (and the first to sink three times itself, killing 25 people) in 1863, a few years later than Monturiol.

Propulsion

No matter how state-of-the-art the Ictíneo was compared to her many contemporaries, she still had the same basic drawbacks many submarines at the time possessed: a limited range as a result of limited air supply, and a very low speed. All early submarines were propelled by human muscle, which made them extremely slow. The Nautilus was equipped with a sail, but this could obviously only be used when sailing on the surface. Underwater, the ship was propelled by a helical screw, turned by hand. The Ictíneo used pedal power, needing four persons to reach a speed of one mile per hour (about the same speed of the underwater rowing boat designed three centuries earlier). That pace was not always sufficient to overcome the effect of currents and tides.

When the Ictíneo I was crushed by a freighter while docked in the port of Barcelona, Monturiol decided to design a larger submarine that was driven by steam. The Ictíneo II, more than twice the length of the Ictíneo I, was launched between 1864 (initially with human power) and 1867 (with steam power). It became the first combustion engine driven submarine in the world. The thinking at the time was that it was almost impossible to run a steam engine underwater because it would use up all the oxygen and convert the inside of the ship into an oven. To overcome this, Monturiol invented a chemical furnace based on a reaction between potassium chlorate, zinc and manganese dioxide – a process that produced enough heat to boil water to run the steam engine. To complement this ingenuity, the reaction gave off oxygen as a by-product.

Snorkel

Monturiol had successfully resolved the two basic obstacles presented to submarine inventors: air supply and mechanical power. In fact, he devised an early form of anaerobic (air-independent) propulsion only to be repeated in the 1940s with the Walter turbine in Germany, and finally with the first atomic submarine, the USS Nautilus. The Ictíneo II was the first of its kind providing its own oxygen, without surfacing regularly or using a snorkel, as seen on the Nautilus. Perplexing is the reality that Monturiol, never having patented his ideas, is absent in many maritime records of the progression of submarines.

On account of all the machinery in the vessel, only two men could fit in the submarine originally designed for a crew of twenty. The Ictíneo II made almost twenty problem free demonstration drives. It could stay submerged for eight hours and plunge to a depth of fifty meters. Monturiol calculated that the maximum possible depth was 500 meters, but chose not to take the risk of diving to this depth. In 1868, shortly after its launch, the groundbreaking Ictíneo II was seized by the shipyard and scrapped, together with her predecessor. The reason? Monturiol could not pay the bills.

Coral Divers

While his competitors devised submarines for military purposes, Monturiol had alternative ambitions. The man was a communist, a revolutionary and a utopian who regarded his invention as a way of improving the life of the working class. He once witnessed the drowning of a coral diver in the coastal village of Cadaqués and he thought his submarine would make coral diving a safer endeavour. The Ictíneo II was equipped with arms to retrieve objects from the sea floor. According to other sources, Monturiol regarded the submarine as a tool for exploring the underworld of the deep sea and as a passenger transportation device.

When his search for independant funding proved unsuccessful, Monturiol attempted to sell his invention to the military. He mounted a cannon onto the Ictíneo II in a last effort to attract investment from Madrid, but the Spanish monarchy regarded the wooden fish with apprehension and was not prepared to invest any money into it. In other countries at the time, military factions saw little potential in submarines – their use went against their understood etiquette of war in those times.

Monturiol also tried to sell his invention to the American Navy after he read about the Civil War and their attempts to make submarines, but unfortunately for him, the war was over before a decision could be made. Ironically, only thirty years later, the Spanish fleet was annihilated by America in the dispute over Cuba, and with it Spain lost the final remnants of its 400 year old world empire. The Spanish vessels were infinitely inferior to their American enemy. Speculatively, an army of submarines may have been able to change the course of history.

Replica’s of both submarines are on display in Barcelona: the Ictíneo I in the garden of the Maritime Museum and the Ictíneo II in the harbour. ←

Replica of the Ictineu I submarine (1859) at the Maritime Museum in Barcelona. Image by Till F. Teenck. (CC BY-SA 2.5).

Replica of the Ictineu II submarine (1864) in Barcelona harbour in 1997. Image by DualFreq (CC BY-SA 3.0).

Detail of the Ictineu II replica. Image by Dalydaly (CC BY 3.0).

Plans of the Ictineu II.

References

Stewart, Matthew. Monturiol’s Dream: The Extraordinary Story of the Submarine Inventor Who Wanted to Save the World. New York: Pantheon Books, 2004.

Rosell, Roca Antoni (2002). “La ingeniería y el proyecto del Ictíneo de Monturiol (1857-1868)”, Scripta Nova, University of Barcelona, Vol. 6, no. 119, August 1, 2002.

Hughes, Robert. Barcelona. New york: Vintage, 1991.

Hollan, Thomas (2005). Monturiol, “The Forgotten Submariner”, Undersea Warfare, Vol. 7, No. 3. Accessible through https://web.archive.org/web/20080328045536/http://www.navy.mil/navydata/cno/n87/usw/issue_26/monturiol.html.

Puig-Pla, Carles &Antoni Roca Rosell (2003). “A spanish project for submarine navigation: Narcís Moturiol and the struggle for democracy”, Icon, No. 9, pp. 128-43.

Rosell, Antoni Roca (2006). “La projecció universal de Monturiol”, Quaderns d’historia de l’enginyeria, Vol. VII. Accessible through https://upcommons.upc.edu/revistes/bitstream/2099/1984/1/RECENSIO4.pdf.

“Important events in ocean engineering history: submarines”, Dr. Stephen Wood, Professional Engineer – Ocean Engineering (website, 1999). Accessible through http://my.fit.edu/%7eswood/History_pg2.html.

Bellis, Mary (2017). “History and Design of Submarines”, ThoughtCo (website), April 8, 2017. Accessible through http://inventors.about.com/od/sstartinventions/a/Submarines.htm.

“Origen y evolucion del submarino”, Antecedentes Historicos (website). Accessible through http://perso.wanadoo.es/pfcurto/anteced.html

Wikipedia, The Free Encyclopedia, s. v. “Cornelis Drebbel”, http://en.wikipedia.org/wiki/Cornelius_Drebbel.

Wikipedia, The Free Encyclopedia, s. v. “Robert Fulton”, http://en.wikipedia.org/wiki/Robert_Fulton.

Wikipedia, The Free Encyclopedia, s. v. “Nautilus (1800 submarine)”, http://en.wikipedia.org/wiki/Nautilus_%281800_submarine%29.

Wikipedia, The Free Encyclopedia, s. v. “Wilhelm Bauer”, http://en.wikipedia.org/wiki/Wilhelm_Bauer.

Wikipedia, The Free Encyclopedia, s. v. “brandtaucher”, http://en.wikipedia.org/wiki/Brandtaucher.

Wikipedia, The Free Encyclopedia, s. v. “air-independant propulsion”, http://en.wikipedia.org/wiki/Air-independent_propulsion.

Friends of the Hunley (website). http://www.hunley.org/.

The Citroën 2CV: Cleantech from the 1940s

In spite of all the high-tech that has been squeezed into cars, the 2CV from 1949 is still more energy efficient than the smallest Citroën today.

If you sometimes wonder why more energy efficient technology does not bring about more energy efficient cars, you should take a look at some vintage Citroën brochures of the legendary French hippie car 2CV or Deux Chevaux (known as the duck or the goat in several European countries). In spite of all the high-tech that has been squeezed into cars since then, the 2CV from 1949 is still more energy efficient than the smallest model of the French car designer today. Why?

The 2CV was produced from 1949 until 1990 and sold almost exclusively in Europe. At the time of its introduction the car had an engine capacity of 375cc, a maximum power output of eight horsepower (DIN-HP) and a top speed of 65 kilometres an hour (40 mph). In 1954 the power was tuned up to ten HP, which brought the top speed at 80 kilometres an hour (50 mph). In 1974 the power output rose to 24 HP, with a top speed of 102 kilometres an hour (63 mph). Later models had an engine capacity of 602cc, a maximum power output of 30 HP and a top speed of 120 kilometres an hour (75 mph).

500 Kilograms

In spite of the much higher performance (an almost doubling of engine capacity, four times as much power output and a top speed almost twice as high) the weight of the hippie car remained the same at about 500 kilograms. Today, there is not one car which comes even close to these figures. The smallest model of Citroën now on the market, the C1, weighs 810 kilograms (despite the use of lighter materials). The Citroën C1 has an engine capacity of 998cc and a maximum power output of 68 HP, and it does 157 kilometres an hour (98 mph).

Compared to the first 2CV models, the weight of the smallest Citroën today has almost doubled, while the top speed more than doubled and the maximum power output rose by a factor of eight. Surprisingly, the fuel consumption remained more or less the same. The C1 consumes 4.6 litres per 100 kilometres (61 miles per gallon), the 2CV consumed on average 4.4 litres. It’s obvious that the engine of the C1 is more energy efficient than the engine of the 2CV, since the latter needed the same amount of fuel to power a much lighter and much slower vehicle.

In other words: if we would apply this modern technology in a car that is as light and slow as a 2CV from the fifties, we would now drive cars that scarcely burn any gasoline. Unfortunately, all technological progress was devoured by more weight, more power, more speed, more comfort and more electronics.

Safety Belts

Part of the extra weight is the consequence of safety measures. Car manufacturers always hammer at this and of course more safety is a good thing. But, because at the same time the speed of the vehicles has raised substantially, and higher speeds mean more serious accidents, part of this progress is negated – just like the higher energy efficiency is negated by the higher performance. Moreover, safety belts are still the most important reason why traffic deaths plummeted since the seventies, and the weight of that mechanism is limited.

Another reason for the higher weight and energy consumption is the advancement of comfort and electronics. The first 2CVs hardly had a dashboard that was worthy of the name. The vehicles had no heating or air-conditioning – there was not even a fuel gauge. If you wanted to know how much gasoline you had left, you had to stop and poke a dipstick into the fuel tank. Until the sixties, the windscreen wipers were driven by the wheels – and therefore did not work when the car was not moving. The windows of the 2CV could not even be opened mechanically, let alone by electricity: they were pushed open with your elbow. In today’s cars all these applications (and dozens of new applications) are run by their own electric motor.

These electronics push up energy consumption because they raise the weight of the car and because they consume energy themselves (electricity which is delivered by the combustion engine). If we really want more energy efficient cars, the 2CV shows us that we need not more, but less technology. ←

A 2CV. Image by Rudolf Stricker (CC BY-SA 3.0).

A 1975 2CV cornering. Image by Andrew Bone (CC BY 2-0).

All 2CVs had flap-up windows. Image by Robert Jaarsema (CC BY 2.5).

Interior of a 2CV from 1951. Image by Berthold Werner (CC BY-SA 3.0).

References

Citroënët (website). www.citroenet.org.uk

Marsch, Julian. “A Series - the 2CV-based vehicles 1949-1990”, Citroenet (website, 1996). Accessible through http://citroenet.org.uk/passenger-cars/michelin/2cv/2cv-index.html.

La 2CV: une legende! (website). http://www.2cv-legende.com/dimensions-2cv.php.

Life Without Airplanes: from London to New York in 3 Days and 12 Hours

If we would stuff people in the Queen Mary II like we fold passengers into airplane seats, the ship could transport more than 500,000 people.

Flying has become cheaper than taking a train or driving a car. Yet, environmental concerns, dwindling fuel reserves and fast rising kerosene prices are threatening to turn airline travel into a privilege for the rich again. This should not mean the end of long-distance travel, however. Before mass air travel took off in the 1960s, people crossed the globe in majestic passenger ships. Reintroducing ocean liners would be more than a nostalgic move: it could be a much more energy efficient (yet slower) way to travel.

Ocean Liners

Airlines all over the world are struggling to lower the energy consumption of their machines – by designing lighter planes and more efficient engines, by getting rid of needless weight inside the cabin, or by flying at lower speeds. At the same time, they started investigating alternative fuels like algae, coconut oil, hydrogen and solar power. None of these things will save cheap airline travel when kerosene prices keep going up, though. There is a limit to energy efficiency, and alternative fuels for airplanes are highly speculative; maybe we should first try and see if we could run our cars on “sustainable” fuels without destroying the environment before we try to implement them in jumbo jets. There is no alternative for kerosene.

It has been said that there are no alternatives to airplanes either, when it comes to long distance travel. This might be true, but this alternative once existed and it disappeared because of planes. From the mid-nineteenth century to the 1960s, millions of people crossed the oceans on passenger ships. Many hundreds of ocean liners were built. Most of these passenger ships were rather small and slow, but the superliners travelling the North Atlantic between Europe and North America were fast vessels with a much larger passenger capacity than that of a present plane.

Motorised ships (first running on coal, later on diesel) brought a spectacular improvement in travel speed. While a sailing ship needed one to two months to cross the Atlantic, the first steamships made the journey in just 15 days. Steamships also made travelling times predictable, so that regular services could be established. Both speed and passenger capacity went up fast during the following one hundred years. The SS United States, which was in service from 1952 to 1969, still holds the record for the fastest ocean liner ever built: she (ocean liners are female) crossed the Atlantic in 3 days and 12 hours, at a speed of more than 54 km/h. That’s ten to twenty times faster than a sailing ship. Contrary to present cruise ships, ocean liners were built for speed. Nations were in a constant race to possess the fastest passenger ship. Ocean liners brought thousands of European immigrants to the US, Australia and Canada. They caused a modest tourist boom in the 1920s and they served as the most important means of transportation between European countries and their colonies.

Yet, the fast growth of ocean liner traffic came to a rather abrupt end when air travel took off. Propeller driven aircraft like the DC-3, which were used in the 1930s and 1940s, revolutionised travel at medium distances, but their speed (240km/h) and range (1,650 km) were still too limited to present a danger for transatlantic ocean liners. With the arrival of jet powered planes at the end of the 1950s, however, ocean liners lost their reason for existence.

The Death of Distance

Most passenger ships were taken out of service in the 1960s – some were converted to cruise ships. Travelling at speeds of 900 km/h, jet powered planes lowered the travelling time between New York and London to less than 8 hours – ten times faster than the SS United States. Jet engines killed distance: today, at least in theory, every place on Earth can be reached in less than 24 hours time.

However, it’s interesting to note that distances shrunk at least as much by switching from sailing ships to ocean liners (which also introduced predictable travelling times) as they did by changing from ocean liners to planes. Today, there’s only one ship left that services transatlantic crossings: the Queen Mary 2. Taking this gigantic ship as an example, replacing air travel by ocean liners does not seem to make a big difference for energy use. At service speed, the ship has an engine output of 90,000 kilowatts. Since she can take 2,620 passengers, this comes down to 34 kilowatts per passenger.

A Boeing 747 has an average engine output of 65,000 kilowatts and can transport about 500 passengers. This comes down to 130 kilowatts per passenger (for comparison: today’s cars can have a maximum engine output from 50 to 300 kilowatts and more). Thus, to transport one passenger across the Atlantic, a plane needs four times more engine power than a ship. Power output does not say all there is to say about fuel consumption however, since it does not take into account the duration of the trip and the fuel efficiency of the engines. It says even less about the emissions of toxic fumes and CO2, because marine engines burn much dirtier fuel than aeroplanes. Therefore, to make a case for a revival of ocean liners, more spectacular gains are needed. These are not hard to find.

500,000 Passengers

While passengers in a plane are squeezed together like sardines, the use of space on a ship like the Queen Mary 2 is far from optimal. The ship might have the speed of an ocean liner, but she is built like a cruise vessel. The Queen Mary 2 shows off 15 restaurants and bars, 5 swimming pools, a casino, a ballroom, a theatre and a planetarium, to give some examples. It has cabins with balconies. In a plane, each passenger is folded into a seat – and that’s it.

How many passengers would fit in the Queen Mary 2 if they would have as less space and leisure options as the passengers of a large jumbo jet? The ship has a gross tonnage of almost 150,000 GT – gross tonnage is a measure determining the internal volume (or enclosed space) of a ship, and comprises all spaces including engine rooms and crew cabins for instance. On the Queen Mary 2, this comes down to 57 gross tonnes per passenger. A Boeing 747 has a gross tonnage of 129 GT – which comes down to 0.26 gross tonnes per passenger. If we would stuff people in the Queen Mary 2 like we fold passengers in airplane seats, the ship could transport more than 500,000 people.

This would make transatlantic shipping definitely more eco-friendly than air travel, even without cleaner and more efficient engines. The Queen Mary 2 transporting 500,000 people would boil down to a power output of 0.18 kilowatts per passenger – comparable to the output of a well-trained cyclist and 700 times more efficient than the engine power per passenger of an airplane. Taking into account the duration of the voyages, the ship scores 70 times better than the plane.

Staten Island Ferry

Surprisingly, there are a few passenger boats that achieve similar figures. The best example is the Staten Island ferry, a passenger service that runs between Manhattan and Staten Island in New York. Ferries generally make far from optimal use of space, because almost they usually take not only passengers on board but also their cars. Since the cars take more space and weigh more than the passengers, ferries are a very inefficient way of transporting people (some of them are also as luxurious as cruise ships). Yet, the Staten Island ferry does not take cars (anymore).

These ferries – which have a passenger capacity of up to 6,000 people – have a gross tonnage per passenger of 0.38 to 0.55 GT. That’s only slightly more than the available space on a jumbo jet. Of course, a trip on the Staten Island ferry only takes 25 minutes, and crossing the Atlantic folded in an airplane seat takes less than 10 hours. Stuffing 500,000 people in the Queen Mary would be a bit optimistic, because the trip would take more than 3 days – a bit of walking space might be very welcome. Transporting more passengers also means you have to take more food and more lifeboats, and it would mean significantly more garbage. Therefore, let’s change those 500,000 theoretical passengers into only 30,000 passengers. This is not a random number.

A Realistic Option: 30,000 Passengers

The Queen Mary 1, who sailed the Atlantic from 1936 to 1967, was just like many other ocean liners converted to a troopship in World War II, often transporting as many as 15,000 American soldiers. On one trip she took 16,082 soldiers – the largest amount of passengers ever transported on one vessel. The gross tonnage of the Queen Mary 2 is almost two times larger than that of the Queen Mary 1, so it must be possible to transport 2 × 15,000 = 30,000 people on a ship like the Queen Mary 2. This would come down to 5 gross tonnes per passenger and 3 kilowatts of engine power per passenger.

These figures closely resemble those of the earlier ocean liners at the end of the nineteenth and the beginning of the twentieth century. The SS Kaiser Wilhelm der Grosse, a German ocean liner launched in 1896, had a gross tonnage of only 14,350 GT but could take 1,506 passengers, which comes down to a gross tonnage per passenger of only 9.5 GT. Even the infamous Titanic had a gross tonnage of only 18.5 tonnes per passenger. If the passengers of the Queen Mary 2 would have the same moving space as the passengers of the (luxurious) Titanic, the ship could still hold more than 8,000 people, three times more than its capacity today (more, in fact, since older steamships had much larger engine rooms). Therefore, transporting 30,000 people on the QM2 is far from unrealistic or uncomfortable. You would need 60 Jumbo Jets to transport 30,000 people.

Sustainable Travel

Every one of those 30,000 passengers on the Queen Mary 2 would have twenty times as much space than a passenger on a plane, while at the same time consuming 43 times less engine power (taking the view that both engines have similar efficiency). Taking into account the duration of the trip, the ship is four times more energy efficient than the plane. Now this looks like an option that could be useful in a peak oil world. If flying would become too expensive for most of us, passenger ships might continue to provide mass travel. We would pay another price, of course: the world would become bigger again. London and New York will be 3 days and 12 hours apart. Engineers could design faster ships, but only at the expense of much higher fuel consumption. The majority of fast ships (hovercraft, catamarans, hydrofoils) were taken out of service because of high fuel costs.

Switching back to ocean liners would surely lower long distance passenger travel and change life as we know it, but it would not be the end of modern civilization, nor the end of tourism or business. A weekend of shopping in Paris will be hard if you live in New York and only have 3 days free. But you could still get anywhere you want, if you take the time. Unfortunately, governments and businesses prefer to keep up their belief in ever larger airports and ever faster planes as if there is no alternative.

One very important note: replacing planes by ocean liners would be an ecologically sound idea, but only if marine engines become cleaner. Most ships make use of very dirty (unrefined) oil that needlessly poisons the air and heats up the atmosphere. This is not a technological but a political problem. All we need is (much) stronger regulation. Other issues to consider are wastewater treatment and garbage disposal – again things that should not be harmful, but at the moment they are because of a lack of sufficient laws and control. ←

The SS Normandie at sea. Image by Altair78 (CC BY 2.0)

The Queen Mary in New York, 1960-61. Image in the public domain.

The SS Bremen and SS Europa, the two largest German ocean liners, 1930. Bundesarchiv (CC BY-SA 3.0).

The SS Nieuw Amsterdam (1940-45). Image in the public domain.

Passenger sitting at the deck of a transatlantic ocean liner (1936-38). Image: Annemarie Schwarzenbach, Swiss National Archives. Image in the public domain.

Passengers on board of the SS Strathnaver, 1936. Image: Sam Hood, State Library of New South Wales. Public domain.

Passengers on board of the SS Aquitania, 1924. Image in the public domain.

Cabin interior of the SS Orcades, c1960. Image in the public domain.

Size comparison of the Titanic, the Queen Mary II, and other vehicles. (CC BY-SA 3.0).

The British liner RMS Queen Mary arrives in New York harbour, 20 June 1945, with thousands of U.S. troops from Europe. Image in the public domain.

New Zealand troops embarking at Lyttelton. Archives New Zealand Patent Copyright office collection (CC BY-SA 2.0).

Soldiers in bunk beds, SS Pennant, 1942. NARA, image in public domain.

References

Demerjian, Dave (2008). “Airline industry begs for help as it fights to survive”, Wired, February 6, 2008. http://blog.wired.com/cars/2008/06/the-internation.html.

Milmo, Dan (2008). “Airbus maker pledges green planes by 2020”, The Guardian, June 3, 2008. http://www.guardian.co.uk/business/2008/jun/03/theairlineindustry.eads?gusrc=
rss&feed=technologyfull.

“Belgian airline says it will cut costs, emissions by slowing down”, Spacedaily, April 23, 2008. ttp://www.spacedaily.com/reports/Belgian_airline_says_it_will_cut_costs_emissions_by_slowing_down_999.html.

Wilen, John (2008). “Airlines Fly Slower to Save Money”, The Moscow Times, May 5, 2008. Accessible through https://web.archive.org/web/20090116090845/http://www.themoscowtimes.com/article/1009/42/362470.htm.

Barkham, Patrick (2008). “Virgin’s biofuel is a PR stunt says BA boss”, The Guardian, March 15, 2008. http://www.guardian.co.uk/business/2008/mar/15/britishairwaysbusiness.globalflyer.

Wikipedia, The Free Encyclopedia, s. v. “Blue Riband”, (accessed July 14, 2019), http://en.wikipedia.org/wiki/Blue_Riband.

Wikipedia, The Free Encyclopedia, s. v. “SS France1960)”, (accessed July 14, 2019), https://en.wikipedia.org/wiki/SS_France_(1960).

Wikipedia, The Free Encyclopedia, s. v. “RMS Queen Mary 2”, (accessed July 14, 2019), http://en.wikipedia.org/wiki/RMS_Queen_Mary_2.

Rumerman, Judy (s.d.). “Boeing 747”, US Centennial of Flight Comission (website). Accessible through https://web.archive.org/web/20121007143215/http://www.centennialofflight.gov/essay/Aerospace/Boeing_747/Aero21.htm.

Bring Back the Horses

Replacing tractors with real horse power could be the revolution that agriculture needs.

Horses and other draft and pack animals revolutionized transportation, war, hunting, manufacturing and agriculture. Work horses formed the backbone of industrial society until the first decennia of the twentieth century, mining coal, ploughing fields and transporting goods and people in fast growing cities. Reintroducing horses in city traffic would be a bad idea – cars might be noisy, dangerous and polluting, but mounts are even worse. In agriculture, however, animal power would bring surprisingly large environmental profits.

Animal Power

For several thousands of years, horses, donkeys, mules, oxen, camels, buffaloes, llamas and elephants were the only means of transportation, next to walking. Animals pulled carts and sledges loaded with goods or people, and trains of pack animals crossed hundreds of kilometres of mountain ranges, jungles and deserts. The arrival of railways and steam machines in the nineteenth century raised the need for animal transport over short and medium distances substantially. Railways, steamships and factories generated a lot of extra freight traffic. Work horses were responsible for the shunting of steam trains and for the hauling of coal to stations and factories. In the mines coal was transported by thousands of horses who never saw daylight.

The rapidly growing human population in cities was transported by horse cabs, omnibuses and trams. In 1890, there were an estimated 300,000 horses in London, which at that time had a human population of around 4.5 million (or 1 horse for every 15 people). In 1880, New York had between 150,000 and 175,000 horses, while the total amount of horses in American cities in 1900 was estimated at three to five million. Not all of these horses were on the streets at the same time, since the animals worked in shifts. Still, at the end of the nineteenth century, the horse population in cities like London and New York became so large that health problems emerged.

Dung in the City

In 1880, the 12,500 horses in a small city like Milwaukee (then 350,000 people) produced 133 tonnes of manure each day – more than 10 kilograms per horse per day. That means that the horse population in London must have produced around 3,000 tonnes of dung per day, of which a substantial amount landed on the paving-stones. On dry days, the muck became dust that stuck to people’s faces and clothes. On rainy days, streets were transformed in open sewers.

Apart from pollution, thousands of iron horseshoes and wheels must have made a terrible racket, and traffic accidents were no less frequent than they are today. Moreover, being a horse in the city at the end of the nineteenth century was not an enviable fate. Pulling carriages crammed with people or goods (sometimes with weights of over ten tons) on dirty and slippery cobble-stones was so exhausting that most animals dropped dead after just a few years of work.

While using pack and draft animals for long distance travel might not be such a bad idea (at least it’s good to know that the end of oil does not necessarily mean the end of international trade), reintroducing horses or other animals in city traffic would be plain crazy. However, the principal reason why horse power is unsuited for city traffic – dung – turns out to be a very interesting quality when it comes to agriculture.

Horses in Agriculture

Replacing tractors with horses would be a good move since horse manure is a perfect fertilizer for agricultural soil. Because tractors don’t produce excrements, fertilizers have to come from somewhere else. That can be manure from animals which are being raised for their meat, or (mostly) artificial fertilizers. In both cases, it takes additional fossil fuels to fertilize the soil – for transporting animal manure to the fields, or for manufacturing fossil fuel based fertilizers (and transporting them too).

Horses have more advantages over tractors. They reproduce themselves, while tractors don’t. That means more oil saved, and other resources like water and metals, because if you switch to horses you don’t have to manufacture tractors. And while tractors need fossil fuels to operate, horses don’t. Switching (back) from tractors to horses would make agriculture almost completely independent of oil and minerals. Horses could mean food security, without any need for importing anything. Moreover, horses don’t emit greenhouse gases worth mentioning (contrary to ruminants like cows) and they don’t pollute the air. Horses might be the solution that agriculture needs.

Fodder or Diesel

Of course, horses need energy too. No fossil energy, but food. This means that replacing tractors with horses would raise the need for additional agricultural land to grow feed for the animals (land that in turn has to be cultivated by extra horses). Tractors could derive their fuel from agricultural land, too, if we turn food crops into bio-diesel or ethanol. Therefore, to know whether it is a useful strategy to replace tractors by horses, we have to know how many extra acres would be needed to feed the horses, and how many acres would be needed to “feed” the tractors.

Such a calculation was published in the American Journal of Alternative Agriculture, eight years ago. With oil prices almost four times lower than today, the researchers might as well have been talking to a brick wall. Today, however, amidst alarming reports on peak oil and food shortages, their findings sound very appealing. Based on the amount of horses relative to crop area in Northern America in 1920 (when only 3.6 percent of farms had a tractor), as well as the amount of horses operated in 1997 on Amish farms, the researchers calculated that America would now need 23 million horses to cultivate the present 147 million hectares of farmland.

Tractor Versus Horse

Taking into account the annual feeds for work horses (1,300 kg of corn grain, 1,600 kg of alfalfa and 500 kg of harvested roughage) and the national yields for these crops during the past decade, they conclude that the 23 million horses would require nine million hectare of agricultural land for food, or six percent of US cropland. To “feed” the tractors with crops, 7.4 million hectares of agricultural land is needed, or five percent of cropland, which makes tractors slightly more efficient than horses.

To make a fair comparison, however, it should also be taken into account that horses make their own fertilizer without any extra energy input and that they reproduce themselves, while tractors need artificial fertilizers and have to be manufactured (and replaced). The researchers express these energy needs in terms of cropland requirements, to be able to compare them with the other results (they take the view that the fertilizers and tractors are produced with energy delivered by energy crops). They also included the energy needed to turn crops into fodder.

The cropland needed to feed the horses then rises to 16 million hectare or 11 percent of US cropland (because of the energy needed to produce fodder from crops), while the cropland needed to “feed” and manufacture the tractors rises to 38 million hectares or 26 percent of American cropland. Conclusion: when everything is taken into account, powering agriculture with tractors requires almost 2.5 times more energy than powering agriculture with horses.

A Swedish study published in 2002 came to similar results: it concluded that a tractor-based agriculture consumes 67 percent more energy than a horse-based agriculture. The Swedish also calculated that the energy input in (local) agriculture increased 13-fold from 1927 to 1981, while total agricultural production in 1981 was only 2.4 times that in 1927.

High-tech Horses

Replacing tractors with horses is not without challenges, though. First of all, there are not enough horses or other draft animals around. Currently, there are some nine million horses in the United States. If we want to reintroduce horses somewhere in the near future – say, when the oil runs out or becomes prohibitively expensive – we better start breeding. Secondly, only a small share of those animals are work or draft horses, one ton muscular beasts with massive hindquarters, who are best suited for pulling weights. If normal riding horses would be used, many more animals are needed. Even if in theory any weight can be pulled by adding more and more light horses, in practice horse spans that are too large become unmanageable.

Horses are not as low-tech and natural as they seem to be. Heavy work horses like the Percheron, the Belgian, the Shire or the Clydesdale are the result of centuries of cross-breeding by man. Unfortunately, these breeds are not doing so well. The situation is not as alarming as it was fifty years ago, when many breeds of work horses were on the brink of extinction. Their numbers have risen again, but the population is still small enough to make them vulnerable to genetic deviations. Furthermore, most of them are now bred for their looks only, and these characteristics do not always correspond with agricultural needs or even a good health. If draft horses become extinct, it would take many centuries to get them back on the scene (horse ‘technology’ also deteriorated after the decline of the ancient empires).

Man Power

Even if we can breed enough work horses, agriculture would have to change. The advantages of a tractor are speed and convenience. It is easier to steer a tractor than a span of horses, and it goes a lot faster. There is not so much difference in velocity, but because of their larger power, tractors can pull wider and heavier ploughs, so that they don’t have to go up and down the field as many times as a horse span. Using several horse spans at the same time makes up for that, but that also means that you need more farmers. Horses also need to be taken care of, seven days a week, even when they are not working. And they might drop fertilizer on the field, but they are not evenly distributing it. All of this means that a horse-based agriculture would demand a lot more man power. More people would have to work in agriculture – while today, in industrialised countries, almost nobody works on the field anymore. Encouraging people to watch a horse’s ass instead of a computer screen might prove difficult.

On the other hand, putting tractors in the stable does not mean going back to the middle ages, and it does not exclude heavy machinery, high yields or high-tech. Horses in agriculture are a fairly modern phenomenon. In antiquity and throughout the middle ages, fields were ploughed by oxen. In Europe and in North America horses took over in the nineteenth century with the introduction of a new generation of machinery that was too heavy for oxen. These machines required much more animal power, but they increased yields and decreased the need for man power substantially. Without tractors.

Lightweight Machinery

In the US in the second half of the nineteenth century, you could see 12-meter wide and 15-ton heavy harvesting machines pulled by spans of up to 40 horses, managed by just 5 or 6 farmers. These were mostly riding horses, since most European draft horses were only imported at the end of the nineteenth century (these purebred animals were usually not working in the field, but only used to “upgrade” the existing horse population through breeding). Today, agricultural machinery is trimmed to powerful tractors. With twenty-first century technology, it must be possible to design extremely lightweight machinery that can combine horse power with high yields, high speeds and easy management. ←

A horse in a field at the Dyfed Shire Horse Farm. Image: Garth Newton (CC BY-SA 2.0).

Twenty-horse harvester at work in a field in California, ca. 1905-08. Image in the public domain.

An Ardennais stallion. Image: Vassil, public domain.

Draft horse in the Netherlands. Rainer Halama (CC BY-SA 3.0).

References

Rydberg, Torbjörn & Jan Jansén (2002). “Comparison of horse and tractor traction using emergy analysis”, Ecological Engineering, Vol. 19, pp. 13-28.

Turvey, Ralph (2005). “Horse traction in Victorian London”, Journal of Transport History, September 1, 2005, Vol. 26, No. 2, pp. 38-59.

Bender, M. H. (2001). “An Economic Comparison of Traditional and Conventional Agricultural Systems at a County Level: Appendices and Expanded References”, American Journal of Alternative Agriculture, September 1, 2001, Vol. 16, No. 1, pp. 2-15.

Peat, Marwick, Mitchell & Co., & American Horse Council. (1987). The Economic impact of the U.S. horse industry: Executive summary. Washington, D.C: American Horse Council.

Several articles on the “Draft Horse in America”, International Museum of the Horse (website). http://imh.org/exhibits/online/draft-horse-in-america/.

Satellite Navigation in the Eighteenth Century

More than two centuries ago, it was possible to very accurately pinpoint your position on earth by means of satellites: the stars.

Man has navigated across the globe by means of satellites for thousands of years. However, until the mid twentieth century, these were not GPS-satellites, but stars. In reality, the sun and the stars aren’t satellites of the Earth, but celestial navigation is based on a precopernican world view (the earth was believed to be the centre of the universe). This may sound a little outdated, but this system was perfected to such an extent that in the second half of the eighteenth century it was almost as accurate as the present-day GPS. Moreover, it was much more robust.

GPS

Satellite navigation is becoming ever more important. In just ten years, navigation devices guided by GPS have become an indispensable instrument in automobiles, and now the technology is conquering the mobile telephone. Satellites are also replacing radar technology [1] for the navigation of ships, trains, planes, spaceships, submarines, tanks and (the reason why the system was originally designed) bombs.

No matter how vital satellite navigation seems to be these days, the thirty American controlled GPS-satellites were only launched into space from 1989 to 1994. Russia also has its own navigation system (that became redundant) and China has put forward developmental schemes for their now relatively limited Beidou system. For some years now, Europe has been trying to scrape together enough money for the building of its own system, Galileo.

Until the year 2000, the GPS-signal was deliberately downgraded to an accuracy of 100 metres by the American military. Since then, the commercial system is accurate to a distance of 10 to 30 metres (horizontal) and 20 to 60 metres (vertical). The US military forces now boast an accuracy range of less than 3 metres, which in combination with other techniques can be augmented to less than 1 centimetre.

Craftsmanship

The GPS-system instantaneously informs users of their three-dimensional position on earth: in terms of degree of longitude (the position relative to the prime meridian in Greenwich), degree of latitude (the position relative to the equator) and altitude (the position relative to sea-level).

To put it bluntly: today, even an idiot can determine his or her position on earth by pressing a button. Some centuries ago, it was possible to achieve a determination of your position on Earth which was almost as accurate as with GPS – but only with time, craftsmanship and significantly more complexity.

Humans did not wait for the GPS to explore the globe. Naval voyages have been undertaken several thousands of years before the start of our era. On land, mankind started roaming even earlier. On terra firma, navigation is relatively simple. A landscape may have many possible orientation points, like mountain ranges or rivers, which can be remembered. On the ocean (or in deserts) those points of reference are much less apparent.

Polynesians

The first seafarers stayed close to the coast and rowed or sailed from island to island. Gradually, they learnt how to make use of clues in meteorological data, such as clouds, currents, wind and waves. Long before the more well know European navigators, Polynesians had crossed thousands of kilometres of ocean in that way. That knowledge was completed with primitive navigation techniques based on the movements of the sun and other stars. In time, more navigation information was passed on to new generations, first orally and later cartographically.

Celestial navigation is mentioned in the works of Homer and Herodotus, in the Bible and the Norse sagas. This long standing history makes it one of the most successful technologies that humans have ever created. Celestial navigation was perfected with the start of the European voyages of discovery, and it continued to be the foundation of all navigation at sea and in the air until the mid twentieth century. To a lesser extent, it was also used at land. Only after World War II it was superseded by radio and later radar navigation. Radio navigation systems were shut down at the end of the 20th century, radar navigation is currently being superseded by satellite navigation.

Shooting Stars

To determine one’s position on earth, one has to be able to find out the degree of longitude (east-west) as well as the degree of latitude (north-south). The latitude (the distance to the equator or the poles) has been easy to determine since antiquity – by measuring the angle of the sun relative to the horizon. Other stars could also be used for this, such as the polar star in the northern hemisphere.

Throughout history several instruments were developed for the shooting of stars, tools that became increasingly accurate and practical: the astrolabium (since the fourth century), the quadrant (since the thirteenth century), cross-staff (seventeenth century), the octant and the sextant (both in the eighteenth century) [2].

The sextant is accurate to a resolution of 100 to 200 metres, depending on the quality of the instrument and the experience of the user. This is as accurate as the commercial GPS network was in 2000. Sextants were also developed for use on land, under water (in submarines) and in the air (balloons and later on aeroplanes and even the first space flight). For use in the air (and on land) the sextant made use of an artificial horizon.

Where Are We?

Determining one’s degree of longitude (east or west) has always been a much harder task. To obtain this information, you have to know the time at the place where your voyage started. Today, this is achieved quite easily by adjusting your clock to the prime meridian (or another fixed position) and later comparing that time with the local time at sea.

The sun circumnavigates the Earth in 24 hours (in reality it is the other way around, as mentioned earlier), which means that it moves fifteen degrees per hour (360 divided by 24). If the time on the ship is three hours later than the time at Greenwich (or another chosen starting point), you find yourself 45 degrees west of your starting point.

The problem was that accurate marine chronometers were only available from the second half of the eighteenth century – before that time it was impossible for sailors to know how long they had been at sea since their time of departure. Land clocks were terribly inaccurate on ships, because of the bobbing, humidity and climate variations.

That’s why sailors made use of the concept dead reckoning. By means of a compass that provided information on direction (used by the western world from the thirteenth century) and a chip log that was used to calculate the speed of the boat, they deduced the possible course and the distance from their starting point – and were then able to calculate the duration of their time at sea.

Chip Log

Computing the speed of the boat was done by throwing an object in the water at the bow of the ship, and then counting how long it took before that object (mostly a wooden beam on a rope) passed the rear end of the ship. Compass and ship log were also used to determine the degree of latitude when the starry sky was obscured by thick cloud cover – the greatest disadvantage of using celestial navigation.

Currents, wind and minor inaccuracies in measurements could lead to large deviations over long distances, which meant that lots of ships perished. Dead reckoning was helped a lot by an occasional point of reference, like an island, that could be used as a new starting point for the drawn course.

An alternative for the determination of the degree of longitude was a calculation utilising moon tables, a method that was invented by astronomers before the arrival of the shipping chronometers. Those calculations, however, demanded several hours, which meant that the information was always outdated.

Lighthouses, Buoys, Lightships & Foghorns

The invention of the marine chronometer around 1760 was the missing link in the navigation system. It was now possible to accurately determine the degree of longitude and precise maps could be made which in turn provided navigational support in cloudy weather.

In addition, a network of lighthouses, buoys and lightships was put in place, providing warnings of dangerous sandbanks or masses of rocks. The first lighthouses were built more than 2000 years ago, but thanks to the substitution of open fires with lamps at the end of the eighteenth century they became a lot more efficient and easier to operate. Ships also used gongs, bells and explosives to warn each other in a thick mist – mid nineteenth century these techniques were replaced by foghorns.

At the end of the nineteenth century marine navigation had evolved, boasting a very reliable system that combined the knowledge of astronomers, mathematicians, cartographers and instrument builders. With the arrival of radio navigation and later on radar and satellite navigation, the whole system however, was quickly dismantled. Lighthouses and lightships were phased out, and now it seems only old and stubborn captains or puritans still use a sextant (which is, luckily, still being sold).

Robust System

Nevertheless, it is important that this prior knowledge is not being lost. GPS has made navigation more accurate, much faster and easily accessible. However, unlike celestial navigation, it is not a fool proof system as it is susceptible to destruction. Celestial navigation is not controlled by anyone, and it can not be destroyed by anyone. Radar technology is more vulnerable than celestial navigation, but it is much more robust than GPS since it is a decentralized system.

Relying on one centrally controlled system for all navigation could be very dangerous. Should anything go wrong with the GPS-satellites, deliberately [3] or by accident, all ships, planes, cars, submarines, backpackers and precision bombs would lose their way. In the field of navigation, we would be catapulted back in time: not to the eighteenth century, but to antiquity. ←

A sextant. Image in the public domain.

A man holding a sextant. Image in the public domain.

References

[1]: Federal Aviation Administration (2006),
“Fact Sheet – Automatic Dependent Surveillance-Broadcast (ADS-B)”. http://www.faa.gov/news/fact_sheets/news_story.cfm?newsKey=
4172)

[2]: Ifland, Peter (2000). “The history of the Sextant” (conference talk), October 3, 2000. http://www.mat.uc.pt/%7Ehelios/Mestre/Novemb00/H61iflan.htm.

[3]: Adams, Chuck, “Kiss your GPS units goodbye. China destroys Satellite with missile”, Tech-archive (website), January 18, 2007. Accessible through https://web.archive.org/web/
20110418140717/http://sci.tech-archive.net/Archive/sci.geo.satellite-nav/2007-01/msg00359.html.

Links & further reading

GSP World: www.gpsworld.com

Celestial Navigation Net: www.celestialnavigation.net has lots of practical information

Atlas Coelestis: www.atlascoelestis.com has an impressive collection of old celestial maps

Ifland, Peter (1999). Taking the stars: celestial navigation from argonauts to astronauts. Malabar, Fla: Krieger.

Email in the Eighteenth Century: The Optical Telegraph

More than 200 years ago it was already possible to send messages throughout Europe and America at the speed of an aeroplane – wireless and without need for electricity.

Email leaves all other communication systems far behind in terms of speed. But the basic principle of the technology – forwarding coded messages over long distances – is nothing new. It has its origins in the use of plumes of smoke, fire signals and drums, thousands of years before the start of our era. Coded long distance communication also formed the basis of a remarkable but largely forgotten communications network that prepared the arrival of the internet: the optical telegraph.

Postal Services

Throughout history, long distance communication was a matter of patience – lots of it. Postmen have existed longer than humans can write, but the physical transport of spoken or written messages was always limited by the speed of the messenger. Humans or horses can maintain a speed of 5 or 6 kilometres an hour for long distances. If they walk ten hours a day, the transmission of a message from Paris to Amsterdan would take more than a week.

Already in antiquity, post systems were designed that made use of the changing of postmen. In these stations, the message was transferred to another runner or rider, or the horseman could change his horse. These organised systems greatly increased the speed of the postal services. The average speed of a galloping horse is 20 kilometres an hour, which means that the distance in time between Paris and Amsterdam could be shortened to a few days. A carrier pigeon was at least twice as fast, but less reliable. Intercontinental communication was limited to the speed of shipping.

Centuries of slow long-distance communications came to an end with the arrival of the telegraph. Most history books start this chapter with the appearance of the electrical telegraph, midway the nineteenth century. However, they skip an important intermediate step. Fifty years earlier (in 1791) the Frenchman Claude Chappe developed the optical telegraph. Thanks to this technology, messages could be transferred very quickly over long distances, without the need for postmen, horses, wires or electricity.

A Chain of Towers

The optical telegraph network consisted of a chain of towers, each placed five to twenty kilometres apart from each other. On each of these towers a wooden semaphore and two telescopes were mounted (the telescope was invented in 1600). The semaphore had two signalling arms which each could be placed in seven positions. The wooden post itself could also be turned in four positions, so that 196 different positions were possible. Every one of these arrangements corresponded with a code for a letter, a number, a word or (a part of) a sentence.

Every tower had a telegrapher, looking through the telescope at the previous tower in the chain. If the semaphore on that tower was put into a certain position, the telegrapher copied that symbol on his own tower. Next he used the telescope to look at the succeeding tower in the chain, to control if the next telegrapher had copied the symbol correctly. In this way, messages were signed through symbol by symbol from tower to tower. The semaphore was operated by two levers. A telegrapher could reach a speed of one to three symbols per minute. The technology today may sound a bit absurd, but in those times the optical telegraph was a genuine revolution. In a few decades, continental networks were built both in Europe and the United States.

The first line was built between Paris and Lille during the French revolution, close to the frontline. It was 230 kilometres long and consisted of 15 semaphores. The very first message – a military victory over the Austrians – was transmitted in less than half an hour. The transmission of 1 symbol from Paris to Lille could happen in ten minutes, which comes down to a speed of 1,380 kilometres an hour. Faster than a modern passenger plane – this was invented only one and a half century later.

From Amsterdam to Venice

The technology expanded very fast. In less than fifty years time the French built a national infrastructure with more than 530 towers and a total length of almost 5,000 kilometres. Paris was connected to Strasbourg, Amsterdam, Toulon, Perpignan, Lyon, Turin, Milan and Venice. At the beginning of the nineteenth century, it was possible to wirelessly transmit a short message from Amsterdam to Venice in one hour’s time. A few years before, a messenger on a horse would have needed at least a month’s time to do the same.

The system was copied on a large scale in other countries. Sweden developed a country-wide network, followed by parts of England and North America. A bit later also Spain, Germany and Russia constructed a large optical telegraph infrastructure. Most of these countries devised their own variations on the optical telegraph, using shutters instead of arms for example. Sweden developed a system that was twice as fast, Spain built a telegraph that was windproof. Later the optical telegraph was also put into action in shipping and rail traffic.

A real European network never really existed. The connection between Amsterdam and Venice existed for only a short period. When Napoleon was chased out of the Netherlands, his telegraph network was dismantled. The Spanish, on the other hand, started too late. Their nationwide network was only finished when the technology started to fall into disuse in other countries. The optical telegraph network was solely used for military and national communications, individuals did not have access to it – although it was used for transmitting winning lottery numbers and stock market data.

Electrical Telegraph

The optical telegraph disappeared as fast as it came. This happened with the arrival of the electrical telegraph, fifty years later. The last optical line in France was stopped in 1853, in Sweden the technology was used up to 1880. The electrical telegraph was not hindered by mist, wind, heavy rainfall or low hanging clouds, and it could also be used at night. Moreover, the electrical telegraph was cheaper than the mechanical variant. Another advantage was that it was much harder to intercept a message – whoever knew the code of the optical telegraph, could decipher the message. The electrical telegraph also made intercontinental communication possible, which was impossible with the optical telegraph (unless you made a large detour via Asia).

The electrical telegraph was the main means of communication for transmitting text messages over long distances for more than 100 years. At first, electrical wires were used; later on radio waves were used to communicate. The first line was built in 1844, the first transatlantic connection was put into use in 1865. The telegraph made use of Morse code, where dots and dashes symbolize letters and numbers. Not the telephone, nor the railroads, nor radio or television made the telegraph obsolete. The technology only died with the arrival of the fax and the computer networks in the second half of the twentieth century. Also in rail-traffic and shipping optical telegraphy was replaced by electronic variants, but in shipping the technology is still used in emergency situations (by means of flags or lamps).

Keyboard

The electrical telegraph is the immediate predecessor of e-mail and internet. Since the thirties, it was even possible to transmit images. A variant equipped with a keyboard was also developed, so that the technology could be used by people without any knowledge of Morse code. The optical as well as the electrical telegraph are both in essence the same technology as the internet and e-mail.

All these means of communication make use of code language and intermediate stations to transmit information across large distances; the optical telegraph uses visual signs, the electrical telegraph dots and dashes, the internet ones and zeroes. Plumes of smoke and fire signals are also telegraphic systems – in combination with a telescope they would be as efficient as an optical telegraph.

Of course, e-mail is much more efficient than the optical telegraph. But that does not alter the fact that the low-tech predecessor of electronic mail more or less obtained the same result without wires or energy, while the internet consists of a cluster of cables and is devouring our energy resources at an ever faster pace. ←

Chappe optical telegraph in Jonquiêrs, Narbonne, France. Image: Romain Bréget (CC BY-SA 3.0)

A replica of one of Chappe’s semaphore towers in Nalbach, Germany. Image: Lokilech (CC BY-SA 3.0)

A Chappe optical telegraph on a church in Montmartre, Paris, Frans. Jacques-Auguste Regnier, 1820.

A Chappe optical telegraph.

Map of the Chappe optical telegraph network in the Low Countries.

Map of the Chappe optical telegraph network in France.

Original semaphore used on the line Antwerp-Vlissingen, restored and photographed in 1992 in the PTT Museum / Museum voor Communicatie, the Netherlands. Peter Denters (CC BY-SA 3.0).

Optical telegraph and control panel.

Drawing of a person operating an optical telegraph.

Controls of a Prussian optical telegraph. Image: Superbass (CC BY-SA 3.0).

French optical telegraph code. Illustration: Patrick87 (CC BY-SA 3.0).

Code used by the Prussian Optical Telegraph between Berlin and Koblenz. Image: Kandschwar, scan from Museum für Kommunikation Frankfurt (CC BY-SA 3.0).

A replica of an optical telegraph in Stockholm, Sweden. Image: CBX (CC BY-SA 3.0).

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