[HN Gopher] SmartFarm device to harvest air moisture for self-su...
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SmartFarm device to harvest air moisture for self-sustaining urban
farming
Author : prostoalex
Score : 50 points
Date : 2021-04-19 15:02 UTC (8 hours ago)
(HTM) web link (news.nus.edu.sg)
(TXT) w3m dump (news.nus.edu.sg)
| bryanrasmussen wrote:
| It's good to know things can be kept running even if there won't
| come soft rains.
| thepangolino wrote:
| How does this compare to a dehumidifier?
| aphextron wrote:
| It is one.
| spiritplumber wrote:
| They usually are (As Thunderf00t shows over and over)
| NortySpock wrote:
| Presumably the absorption bed system requires less power than a
| refrigeration based system, at the cost of lower throughput.
| hef19898 wrote:
| Well, Space Pirate might be an unrealistic career option. So I
| have to settle for Moisture Farmer. Maybe some hermit from the
| hills will come and train in some form of elegant combat from a
| less barbaric period.
| finnh wrote:
| A desert hobo, you say?
|
| https://www.youtube.com/watch?v=RySHDUU2juM
| spiritplumber wrote:
| If water shortage is an issue, Space Pirate may be the way to
| go, though. https://www.imdb.com/title/tt0087451/
| hinkley wrote:
| Years ago someone pointed out that the whole alien invasion
| thing doesn't make that much sense because you're deep in a
| gravity well at that point, and there are plenty of resources
| in the Oort cloud and the outer asteroids.
|
| More likely for a sentient species to watch helplessly as an
| advanced civilization strip mines their outer system of
| resources long before they can get to them, and not only not
| be able to even throw rocks high enough to hit them, but
| perhaps find themselves stranded there not even able to take
| proper revenge.
| rmah wrote:
| A nice science project and possibly of use in desert climates or
| in tiny, extremely densely populated, nations like Singapore. But
| I don't see how it would be viable or why it would be needed for
| the vast majority of the world's agriculture. Rain is free.
|
| "two of the world's biggest problems - water scarcity and food
| shortage"... neither of these are big problems, or even problems,
| for the "world". Water scarcity is a problem in a few areas. The
| world produces multiple times more food than humans could
| possibly eat (most is fed to animals). Any famine is a
| local/social/logistical/political problem.
| hinkley wrote:
| Rain is mostly free if ocean is all that is downwind of you.
| Most of the West Coast of the United States is lush because the
| terrain catches most of the water that would otherwise flow
| much farther inland.
| foxyv wrote:
| The only reason I've seen for vertical farming that makes any
| sense right now is that you can control the environment without
| damaging the ecosystem around you. Filtered air so no cross
| pollination with wild strains, no insects, recycled water so no
| runoff or wasted fertilization, perfectly regulated
| soil/hydroponics, no PH issues from rain, no herbicides, etc...
| Good for high value, difficult to raise crops. Usually stuff
| that costs an arm and a leg like pink lettuce, white asparagus,
| hop shoots and wasabi root.
|
| Otherwise the entire thing is too expensive. Usually water is
| more expensive in urban areas and power costs are prohibitive.
| Then you have the cost of capital to build a giant building
| that can support extremely heavy equipment for grow beds. You
| can't just use an old office building to support a couple
| thousand tons of equipment unfortunately.
|
| But the thing is, right now there is so much arable land we can
| have luxuries like cattle and farmed wild game. In 80 years we
| may not be able to maintain those luxuries for 10.5 billion
| people without vertical farming. Especially since a lot of
| those people are starting to become more affluent on average. I
| wouldn't be surprised to see beef prices go above $20-30 a
| pound before the end of my life. Even accounting for inflation.
| Maybe VF will become economical by then?
| throwaway1777 wrote:
| Cattle are not a luxury, they are literally part of
| subsistence farming in many regions and an important part of
| the ecosystem. One of the reasons we have to use so much
| fertilizer is because we stopped letting cattle graze over
| the fields. Monocrop corn and soy fields are a far bigger
| problem for sustainability than people think, maybe as bad as
| industrial animal farming.
| splistud wrote:
| History shows that 3 things are important for food
| security: live animals for milk or slaughter, grain that
| can be stored, and any local food that can be easily dried.
| Before we react that food security isn't really a thing
| anymore, history has something to say about that as well.
| And yet the foolish are advocating for 2 of these safety
| nets to be disposed of.
| michaelbrave wrote:
| I dunno, if you talk to any farmer's out in the western US
| water is a big deal, it's what determines where
| cities/settlements were built, it causes political strain
| (Colorado vs Kansas on water rights - Colorado has opted to pay
| fines rather than send water to Kansas) and is in many ways
| unsustainable (California imports a lot and grows crops that
| are not drought friendly like Pistachios, forcing droughts to
| be a different beast than 50 years ago). In a lot of ways water
| scarcity is one of the most underlying political forces for the
| western US, though few would know it unless they looked deeper.
|
| I also think it would hold some promise as we de-
| desertification parts of the world (they are making some
| progress in the Sahara and also the Badain Jaran in
| Mongolia/China). Which is important as deserts can creep up and
| take over places, it's especially concerning as we lose tons of
| topsoil as we did in the midwest during the dustbowl, and
| without proper soil management could turn prime farmland into
| deserts.
|
| Having more water options for dry areas can only be a good
| thing.
| thinkcontext wrote:
| Without any cost information we can't really tell anything
| about the viability of this technology. For example, water in
| CA ranges from $90 per acre foot from the State Water Project
| to $3000 for reverse osmosis of seawater.
| realce wrote:
| The amount of electricity it would take would be insane and
| then you're pulling rain out of the atmosphere, impacting
| your neighbors and region overall.
|
| More water is great, but these things + "urban farming" is
| just a sales pitch.
| spullara wrote:
| Or you can use solar power integrated with the device:
| https://www.source.co/
| calvinmorrison wrote:
| aren't these things just dehumidifiers?
| realce wrote:
| super fancy ones with lots of filters basically -- look
| up "atmospheric water generator" on amazon to see the
| types that are on the market for home use
| spullara wrote:
| Reminds me of Lanai which uses pine trees to capture water from
| the air as it gets little rain.
|
| https://everything-everywhere.com/the-pine-trees-of-lanai/
| curiousfab wrote:
| There have been quite a few startups based on the same idea
| (Waterseer etc.) and I think the common consensus is that these
| devices (which are basically dehumidifiers) are not viable.
| Thunderf00t has some youtube videos about the Waterseer in which
| he breaks down the physics behind it.
| swagtricker wrote:
| "But I was going into Tosche Station to pick up some power
| converters!"
| hef19898 wrote:
| "You can do that when the new droids are ready. And before you
| ask, I need you for an other season before you can go to the
| academy."
| JoeAltmaier wrote:
| Definitely a niche product. Hope the niche is big enough to make
| a go of it!
| gsich wrote:
| >Atmospheric humidity is a huge source of freshwater but it has
| remained relatively unexplored.
|
| Yes, mainly because it's not a "huge" source.
| dale_glass wrote:
| Almost certainly nonsense. Similar things have been tried before,
| and as far as I know none worked. Reasons:
|
| * If you have high humidity, you almost always have plentiful
| rain and water around.
|
| * If you're in a desert, then there's extremely little for any
| device to work with.
|
| * It takes absolutely enormous amounts of air to extract
| meaningful amounts of water even in favorable conditions. * It
| takes a huge amount of energy, too.
|
| * Any such scheme isn't reliable in any case, and especially
| unreliable when things are dry and you really need the water. It
| works best precisely when you don't need it.
|
| * You don't want to drink water from any kind of dehumidifier. It
| may have started clean, but won't stay that way.
| loloquwowndueo wrote:
| The scale is smaller but i have seen these machines
| https://www.waterfromair.co.za/ which do condense ambient
| humidity, filter and purify it and leave it in drinkable form.
| They look like water coolers without the giant bottle and
| function like a kind of dehumidifier with some additional
| steps.
|
| Probably makes sense in a smaller scale "let's replace our
| water coolers because water is scarce but we have enough
| energy" scenario like South Africa.
| DarmokJalad1701 wrote:
| Plentiful of rain need not equal plentiful of water around.
|
| There are states in India for example that get 2000+ mm of rain
| every year and still have severe water shortages.
| bakatubas wrote:
| Is that because folks are pooping in the rivers? You'd think
| folks could just catch rainwater. Sounds like an
| infrastructure issue...
| data_acquired wrote:
| No, no large-scale pooping in rivers. Far more complicated
| than a single technological fix can handle.
|
| Areas which get 2000+ mm of rainfall a year aren't always
| the ones with the most intensive agriculture. Water
| shortages are partly because of (a) the huge variation in
| the amount of rainfall from year-to-year in any area in
| India, and this variation has grown with climate
| change/warming (b) rivers down in the south of the country
| are not perennial but largely rain-fed during the monsoon.
| So "build more dams/infrastructure" doesn't make sense if
| there's not much rain to feed the rivers, (c) certain crops
| grown (sugarcane,paddy) just require tons of water, and are
| more likely to face issues due to variable rainfall
| compared to something like millet cultivation (d) rain is
| required not just for flow into rivers but for recharging
| groundwater, which is then used for agriculture. So, no
| rain = no groundwater and not just no rain = less flow in
| rivers.
| HideousKojima wrote:
| Which highlights another problem with systems like these:
| Humans generally settle near sources of water already. The
| problems with water in poor countries is generally not one of
| water availability, but of water treatment.
| ripply wrote:
| > It takes a huge amount of energy, too
|
| This will often be more expensive than having a truck bring the
| water to you when running a dehumidifier especially when you
| are looking to get out enough for farming.
| pedro1976 wrote:
| I don't believe this will work but due to its complexity. And
| even if it will work, the life expectancy of some parts like
| solar panels is rather short. IMO projects like fog catchers
| [0] look much more promising.
|
| [0] https://edition.cnn.com/2016/11/18/africa/fog-catchers-
| moroc...
| tdeck wrote:
| Fog fences are used in some places to gather a small amount of
| water: https://en.wikipedia.org/wiki/Fog_collection?wprov=sfla1
| spullara wrote:
| It turns out there are a lot of places with humidity but little
| rainfall. Most of California being one but also places in the
| middle east. Believe it or not, there are high humidity
| deserts. There are several companies doing this not for farming
| but for drinking water. Like Zero Mass Water:
|
| https://www.source.co/
| jbunc wrote:
| Agreed
| temp667 wrote:
| They do have uses is marketing. Vodka has a moisture harvested
| vodka "made with fog". It goes for 125 per bottle and is
| usually sold out as far as I can see.
|
| That's a $100 premium which values the "fog" water at roughly
| $500 / gallon. So if you have a market willing to pay $500 /
| gallon extra for water harvested from the air this business
| might work. Not sure how many of those there are.
| throwaway894345 wrote:
| I'm not an expert by any means, but your comment reminds me of
| various nature documentaries in which desert species in certain
| locales would collect dew in the morning before it evaporates.
| Conceivably at least in such places it suggests that there _is_
| ample moisture in the air, and indeed if nature can get it out
| of the air then likely we could too. Conceivably an array of
| metal funnels leading to a bottle or tank (underground or
| otherwise protected from evaporation) could naturally harvest
| the moisture in such areas, even without a special hydrogel.
|
| > huge amounts of energy
|
| Condensation doesn't require energy. The energy mentioned in
| the article seems to be releasing the water from the hydrogel,
| but in my off-the-top-of-the-head metal funnel example a
| sufficiently steep big metal funnel can collect the water
| without any mechanical energy at all.
|
| > Any such scheme isn't reliable in any case, and especially
| unreliable when things are dry and you really need the water.
| It works best precisely when you don't need it.
|
| Water is stored easily enough, as long as you keep a surplus on
| hand for dry spells I don't see the problem?
|
| EDIT: I am curious why my post is being downvoted. This doesn't
| seem particularly controversial.
| dale_glass wrote:
| Condensation requires energy input, or a considerable change
| in temperature.
|
| Hot air can hold a lot of moisture, cold air can hold less.
| Water condenses on surfaces when the air cools down to the
| point that air would have to carry more water than it can at
| the new temperature.
|
| Problem with that: it only works great in very humid areas.
| If you're in a desert, and have 10% humidity, you have to
| cool down your air by a lot for it to become too saturated
| and condensation to happen. Not enough cooling, and the
| moisture stays in the air.
| throwaway894345 wrote:
| Thanks for the detailed information; that was genuinely
| informative, but I'm starting from the assumption that the
| required temperature swings must be present in at least
| some desert ecosystems as evidenced by the aforementioned
| documentaries. As the sibling noted, many deserts cool down
| quite a lot in the evenings.
| outworlder wrote:
| > If you're in a desert, and have 10% humidity, you have to
| cool down your air by a lot for it to become too saturated
| and condensation to happen.
|
| Deserts tend to have pretty wild temperature swings. They
| usually cool down at night. So much so that in most cases
| you can make ice. You can use the sky as a heat sink
| (effectively radiating heat into space).
|
| https://www.fieldstudyoftheworld.com/persian-ice-house-
| how-m...
| outworlder wrote:
| > * You don't want to drink water from any kind of
| dehumidifier. It may have started clean, but won't stay that
| way.
|
| Why?
|
| I have seen how gross dehumidifiers can be. But they are
| designed to dehumidify, not to provide drinking water. What is
| preventing one from purifying the water and keeping it that
| way?
| stakkur wrote:
| I partly agree. But there's a long history of collecting
| moisture in the desert. For example:
| https://en.wikipedia.org/wiki/Air_well_(condenser)
| splistud wrote:
| Put another way, if there is enough humidity to work with then
| there are plants which have evolved to take in that humidity
| more efficiently than any apparatus. Imagine trying to design
| something that could compete with bamboo or certain bushes for
| extracting humidity from the air and either using it or
| transferring it to the surrounding microclimate.
| cobookman wrote:
| Currently in the bay area its 60-80% humidity. It also hasn't
| rained for weeks.
|
| In the summer, certain parts of the Bay Area still has high
| humidity levels without rain for months on end.
| f6v wrote:
| > Currently in the bay area its 60-80% humidity. It also
| hasn't rained for weeks.
|
| This brings back my summer Berlin memories. The temperatures
| are pushing 40, the air is so thick you feel like in Amazon
| rainforest. But no rain in sight.
| mike_d wrote:
| You would need to extract 814,891,540 gallons of water to
| equal 1 inch of rainfall on just the city of San Francisco.
|
| Some basic napkin math says at normal temp and humidity that
| is roughly 84 cubic miles of air you'd need to reduce to 0%
| humidity. Assuming the process isn't instant, you couldn't
| contain that volume of air in a structure humans know how to
| build. You'd also have to build massive air inlet pipes going
| 5 miles in each direction just to be able to circulate it
| into the machinery.
|
| Edit: the comment I replied to was talking about areas with
| "humidity but not rain." I was just pointing out trying to
| replace rain is an insurmountable problem. You can do all
| sorts of things to optimize water usage, but that isn't the
| point. I picked San Francisco because it is a scale most
| people on HN can understand, but it is still tiny compared to
| farmland in the central valley.
| cobookman wrote:
| Yes and No. What percentage of the rain ended up back in
| the ocean? Suspect a very small percentage of rain actually
| ends up being used by humans.
|
| You just need enough for the water that ends in taps or in
| the garden/farm.
|
| I'm not saying this is preferred over desal, water
| recycling, or other water conservation/generation
| possibilities.
| swiley wrote:
| Air circulates naturally, this idea won't work at all for
| other reasons but your calculations are:
|
| 1) for the whole city when these things are usually
| intended for households (and cities have many miles of
| pipes anyway.)
|
| 2) without mention of the rate of water extraction or
| energy use per liter which is usually what makes these
| obviously useless.
| bradfitz wrote:
| The text says:
|
| > This material is extremely absorbent, and takes in moisture up
| to three times its weight.
|
| The image says:
|
| > [...] and takes in moisture up to 300 times its weight.
| gus_massa wrote:
| I guess a typo transformed a 300% into a x300.
| ada1981 wrote:
| Or is it the other way around? If its really light, it could
| be 300x it's weight.
| gus_massa wrote:
| I looked at the research paper
| https://onlinelibrary.wiley.com/doi/10.1002/adma.202002936
|
| > _Herein, a novel copper(II)-ethanolamine complex (Cu-
| complex), which has a maximum water uptake of up to 300%
| and a water production rate of 2.24 g g-1 h-1 under natural
| sunlight, is reported._
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