[HN Gopher] Cement recycling method could help solve one of the ...
___________________________________________________________________
Cement recycling method could help solve one of the big climate
challenges
Author : timthorn
Score : 299 points
Date : 2024-05-23 18:03 UTC (1 days ago)
(HTM) web link (www.cam.ac.uk)
(TXT) w3m dump (www.cam.ac.uk)
| gnabgib wrote:
| There was some discussion yesterday [0] (21 points, 4 comments)
|
| [0]: https://news.ycombinator.com/item?id=40446764
| dr_dshiv wrote:
| Incredible! They use a massive arc furnace (used for steel
| recycling) to recycle concrete. They suggest that solar power
| could power the arc furnaces, resulting in zero emission
| concrete. As concrete currently constitutes 7.5% of anthropogenic
| carbon emissions, this tech could make a big difference.
|
| Arc furnaces are crazy energy intensive. But if solar power keeps
| doubling every 2 years, we will very soon have way more power
| than we know what to do with (at certain times in the day). Arc
| furnaces are a good way to suck up the negative electricity spot
| prices!
| tempestn wrote:
| Often the problem with using excess solar capacity is that the
| capital cost of the thing that would use it (desalination
| plants are one example) is so great that it's not cost
| effective to leave them idle at other times of the day. Any
| idea whether that would be the case with these arc furnaces as
| well?
| ahi wrote:
| IANAMetallurgist. Arc furnaces for steel making already rely
| on cheaper off peak power, so utilization is already a
| factor.
| s1artibartfast wrote:
| I didn't think they varied their use pattern by time of
| day.
|
| They might rely on cheaper power to lower the average cost
| make financial sense, but that is a different than soley
| utilizing excess power.
|
| If they cant rationalize the opex running 8 hours a day,
| there is still a problem. My understanding is that many of
| these plants cant even shut down and be restarted.
| kragen wrote:
| the normal kind of arc furnaces are shut down many times
| a day; it's a batch process, not a continuous one
| s1artibartfast wrote:
| Do they operate 24/7?
|
| Even if it is batch process, going from 24 hours to 8
| hours is like tripling plant cost vs productivity.
| kragen wrote:
| tripling capex vs. productivity, yes, but maybe if capex
| is small compared to opex, that's a worthwhile tradeoff.
| the one particular plant i was able to find the answer
| for does operate 24/7
| adgjlsfhk1 wrote:
| don't forget wind. there's lots of wind power and very
| low power consumption at night. it's probably more like
| 22 hours to 16
| bluGill wrote:
| They generally will run the cheapest electric rates. They
| commonly run only the overnight shift when electric is
| cheapest - it is worth paying the employees that extra
| money to work the overnight shift. They commonly shutdown
| the entire month of December for yearly maintenance -
| when Christmas lights add additional electric demand.
| They coordinate with the power company for other
| shutdowns.
| colechristensen wrote:
| You may be thinking of aluminum plants which can't be
| shut down and restarted without significant damage, but
| they are indeed still throttled up and down. In that case
| it's electrochemistry at high temperatures to strip the
| oxygen off of aluminum. If it gets cold the apparatus
| gets damaged, but it can be throttled down a significant
| percentage.
| kragen wrote:
| thank you, that is almost certainly what they were
| thinking of
|
| how much do they get throttled up and down, and how
| frequently? i'd like to read more about this
| avianlyric wrote:
| Arc furnaces tend to be first in line to voluntarily
| shutdown to deal with grid instability, or projected
| power shortages. Network operators will basically pay
| them equivalent amount of money as they would to buy
| electricity, if the furnace operator is happy to shutdown
| at a moment's notice.
|
| After, to a power grid, removing large loads are
| functionally equivalent to adding additional generation.
| So if you're operating an arc furnace, and can shutdown
| quickly (which arc furnaces can), then grid operators
| will pay you for _privilege_ of being able to shut you
| down at moments notice, and then pay even more for the
| electricity you're not consuming, if the grid is forced
| to call upon that additional "capacity" due other issues
| on grid.
|
| I'm not sure if arc furnaces today vary their usage in
| direct response to variable electricity prices through
| the day, rather than only acting as emergency ballast to
| be jettisoned in an emergency. But I would be very
| surprised if they didn't, they're a large enough load
| that they'll have coordinate the usage with their local
| grid, and large enough that shifting the usage pattern to
| avoid high cost peaks would save them a very material
| amount of money.
| kragen wrote:
| there's some footage in the documentary i linked of
| coordinating the usage with their local grid before
| turning the arc furnace _off_ for half an hour (because
| the next load of scrap was delayed)
| 8372049 wrote:
| [deleted due to severely condescending comment below]
| kragen wrote:
| it's good that you're starting to learn some of the
| basics of how real-time energy markets work, but most of
| the things you have said are unfortunately nonsense
| 8372049 wrote:
| What an exceptionally unconstructive and condescending
| comment.
| kragen wrote:
| oddly enough, that's what i thought about your now-
| deleted misconception-filled comment, but i thought maybe
| it was worthwhile to try to engage positively
|
| guess i failed at that
| Dylan16807 wrote:
| Deleting yours removes any hope of a conversation.
| 8372049 wrote:
| Didn't seem like there was much hope of that with the
| response I got anyway. I'm not here to take condescending
| comments with no substance (i.e. pointing out why it
| supposedly was nonsense), so I decided it was better to
| remove the comment and move on.
| Dylan16807 wrote:
| Okay but this way it's hard not to treat it as if you did
| in fact post nonsense.
|
| And whether you said something right or wrong I at least
| would have liked to see it. Especially when it gets a
| callout like that.
| kragen wrote:
| if you want to read plausible misconceptions about
| electric grid operations and stability you can get gpt-4
| to generate an unbounded stream of them
| 8372049 wrote:
| > Okay but this way it's hard not to treat it as if you
| did in fact post nonsense.
|
| All the more reason for me to stop engaging, isn't it?
|
| The gist of it was that nuclear power is insufficient in
| and of itself because it is hard to regulate output to
| match grid requirements, and therefore that we need both
| nuclear and renewable energy sources, not just one or the
| other. Maybe I'm wrong, maybe I'm not, I'm out of here
| either way.
| Dylan16807 wrote:
| > All the more reason for me to stop engaging, isn't it?
|
| No, I don't think so. The skepticism all comes from your
| initial comment, not the followups.
|
| > The gist of it was that nuclear power is insufficient
| in and of itself because it is hard to regulate output to
| match grid requirements, and therefore that we need both
| nuclear and renewable energy sources, not just one or the
| other. Maybe I'm wrong, maybe I'm not, I'm out of here
| either way.
|
| Oh well that specific point is wrong. Modern nuclear can
| adjust its output quickly and within a wide range if the
| operator wants it to. We could run a 100% nuclear grid.
| The fundamental issue at hand is price, not capability,
| because reducing output makes the cost per watt go up.
| Gibbon1 wrote:
| This is one of the reasons I believe 'base load' demand is
| more fungible than people assume.
|
| I think in California 6% of electricity demand is pumping
| water. I'm almost willing to go on record and say that's
| the California Aqueduct and the actual number is higher.
| Okay I'm going to look.
|
| https://www.ppic.org/publication/water-and-energy-in-
| califor...
|
| > The water system uses approximately 20% of the state's
| electricity and 30% of its natural gas for business and
| home use, according to data from 2001--accounting for more
| than 5% of California's greenhouse gas emissions.
| samatman wrote:
| Did you miss the stat directly underneath that?
|
| > _Heating and other energy-intensive water uses in homes
| and businesses make up almost 90% of water-related energy
| use, while treatment, pumping, and conveyance of water
| and wastewater account for the rest._
|
| That's 2% for everything which isn't heating water.
| Pumping is some smaller fraction of that.
| abakker wrote:
| you are right. The thing that is interesting is that
| pumping loads overall take a lot of the grid's energy,
| it's just that most pumps are refrigeration loads, not
| water transport.
| avianlyric wrote:
| Great thing about heating water, is that it stays hot
| after you've heated it.
|
| Water heating is basically the poster child for "demand-
| response" technologies. You can easily heat your water a
| few hours earlier than normal with basically no
| consequences to the user. But you need to get reasonable
| smart about modelling people water usage, as people don't
| tend forget or forgive a cold shower.
| practicemaths wrote:
| What about tankless water heaters? You can eliminate
| greenhouse gas emissions for heating and be more
| efficient with energy usage overall.
| adgjlsfhk1 wrote:
| tankless heaters use slightly less energy, but they use
| it in a really annoying way. the optimal design for a
| heavily renewable grid is a heat pump water heater with a
| tank
| blitzar wrote:
| The optimal design for a heavily renewable grid is solar
| water heating a tank in home whenever the sun shines,
| falling back on a heat pump water heater with a tank.
| practicemaths wrote:
| That's for maximizing energy efficiency. Tankless I think
| might be a tad bit more easier and cheaper to implement
| than this.
|
| Regardless the point is eliminating the use of natural
| gas in heating water is itself a benefit.
| organsnyder wrote:
| That's only optimal if you know you'll need 100% of the
| heated water (or have a way to store it). While
| photovoltaics are going to be less efficient than direct
| water heating, you can direct the energy to other uses if
| you don't need more hot water.
| bluGill wrote:
| Large tanks of water are about the cheapest way we know
| of to store energy. Batteries store more energy, but are
| extremely expensive.
| organsnyder wrote:
| Yes, but that only matters if we can easily consume that
| energy. If we need the hot water, then that's easy--no
| conversion loss. Otherwise, it gets trickier, especially
| in a small-scale setting like a home.
| bluGill wrote:
| All homes use at least some hot water for showers. In
| many climates they can use a lot of energy for heating
| which means a very large tank could be useful in winter.
| Gibbon1 wrote:
| I read a study looking at the difference between tankless
| and tank water heaters.
|
| Summary the more hot water you use the smaller the win is
| for tankless.
|
| Other thing I've read and seems true is gas and heat pump
| water heaters cost about the same to run. I installed a
| heat pump unit five years ago. Works okay for two people.
| If you had three teenage girls and a wife that likes
| baths a tankless would be a better choice.
| XorNot wrote:
| There's been other responses here pointing out that
| municipal water delivery pumping probably isn't a large
| electricity consumer, but it's also worth noting that
| even if it was you _can 't_ voluntarily shutdown water-
| delivery in large distribution systems - you have to
| maintain pressure and flow to prevent back contamination
| of the system from leaks. It's why you get boil-water
| advisories when there's a general outage - because dirt
| and bacteria can get back into the pipes and it takes
| time to be sure they've been flushed out of the system.
| kragen wrote:
| i didn't know what ahi said (that minimills already depend on
| cheap off-peak power) but intuitively i would expect an arc
| furnace to be pretty cheap compared to the power it uses;
| it's just a water-jacketed chamber lined with castable
| refractory with a lid with three big carbon electrodes
| lowered through it, and all of those are cheap materials and
| low-precision (tight tolerances won't withstand white-hot
| flaming steel for long). the machinery is large and heavy,
| but only in proportion to the volume of material it
| processes. the electrical energy consumption, on the other
| hand, is comparatively enormous
|
| (admittedly maybe the capex for running the power lines to
| the facility is significant, but in the same proportion to
| the cost of the energy used as running transmission lines
| anywhere else)
|
| there's a nice video illustrating the process at
| https://www.youtube.com/watch?v=T1CJ5NPW8MU. don't be
| alarmed, the part that looks like a major industrial accident
| is just what happens normally when they turn it on. a more
| detailed documentary with explanations, though unfortunately
| of an atypically large arc furnace, is in
| https://www.youtube.com/watch?v=eZRuVEfxIVI
|
| in that particular case they say it runs 24/7
| UberFly wrote:
| "the part that looks like a major industrial accident is
| just what happens normally when they turn it on"
|
| That was better than most fireworks displays. I checked the
| second video but don't understand the German explanation.
| Is that just the initial effects of the massive amounts of
| voltage?
| kragen wrote:
| it's pretty moderate amounts of voltage actually, only
| about 300-900 volts, just a little higher than i plug my
| phone charger into. it's just massive amounts of
| _current_ , resulting in massive amounts of heat, which
| sets fire to the impurities and/or boils them off. you
| need low voltage because the arcs are pretty low
| resistance, so getting the necessary power requires tens
| of thousands of amps, about the same as a lightning
| strike. an hour-long lightning strike
|
| (the power of a lightning strike is much higher than that
| of a steelmaking arc furnace because it has much higher
| voltage, possible because the conductive path through the
| plasma is kilometers long instead of centimeters long)
|
| youtube has automatically translated subtitles which
| worked pretty well here. the relevant yt-dlp flags are i
| think --write-sub --write-auto-sub --sub-lang en,es
| (season to taste) and then the j key in mpv cycles
| through the languages you chose. this is also possible
| from youtube's web ui but enormously more awkward
| flakeoil wrote:
| I see they use water to cool the actual furnace encasing.
| They then lead out the warm water to big basins to let the
| water cool off. It would be good if they could use that
| warm water for remote heating of houses or create
| electricity or something.
| roughly wrote:
| The desalination debate is always a little interesting for me
| - first, I'm curious what they're pricing in as the lifetime
| of the plant, because I always hear the capital costs are too
| high, but that's a function of total water produced, and
| second is that the demand for water is pretty friggin'
| inelastic, and as a Californian, I'm pretty sure the supply
| is constrained. I'm convinced that at some point we're going
| to be very, very sad that we talked ourselves out of building
| those plants.
| krallja wrote:
| Call Mark Cuban, make the investments now!
| pjc50 wrote:
| California has plenty of water, it's just dedicated far too
| much of it to farming in what would naturally be arid
| areas. It would be politically impossible to make farmers
| pay the real price for desalinated water, so what might
| happen is retail customers have to pay the high price for
| desalinated water while the remaining ""free"" water is
| routed to agriculture.
| abdullahkhalids wrote:
| The important thing here is that it only recycles concrete.
| Most of the 7.5% emissions are from new concrete constructions
| - new roads and new buildings - as we increase the total
| concrete in use. Very little is from old buildings/roads being
| destroyed and then replaced by something else.
|
| This will make a small dent in the 7.5% at scale.
| marcosdumay wrote:
| Once you solve energy producing and handling, 100% of the
| remaining is composed of tiny little problems.
|
| This one is large enough for several companies to make a
| living. What means it's large enough to care about.
| s1artibartfast wrote:
| I dont understand your point. Are you saying there isnt
| enough recyclable concrete to meet the demand for new
| construction?
|
| If we create half as much concrete waste as demand, that 7.5%
| could drop by half.
| trimethylpurine wrote:
| Home Depot seems to suggest that old concrete is already in
| high demand. If we need it for roads and we can't get it
| because concrete is more valuable, now we have to go find
| road building materials. Is the manufacture of road
| building materials cleaner than concrete?
|
| https://www.homedepot.com/c/ah/how-to-dispose-of-
| concrete/9b...
| s1artibartfast wrote:
| I dont think that suggests there is a high demand for
| used concrete. It does however highlight the fact that
| there may be insurmountable transportation and handling
| costs for recycled concrete.
|
| It is hard to imagine it being cost effective to
| transport it to recycling centers.
| XorNot wrote:
| But it's already transported. You can't demolish an old
| concrete structure and just leave the rubble there. Old
| concrete is already moved to sites to crush it down to
| gravel for re-use in other applications.
|
| The issue is whether the extra transport would offset any
| benefits - which I'd say is unclear. i.e. even if you had
| to truck this stuff to ports and put it on ships...that
| could be worth it, because we already truck every
| component of concrete around.
| szvsw wrote:
| Using demolished concrete rubble in roads is pretty much
| the lowest form of recycling possible. Up-cycling it so
| you can make new cement and ultimately new concrete which
| can be used _structurally_ at a huge carbon advantage is
| far more valuable - most certainly from a carbon
| perspective and likely from a financial one as well.
| baq wrote:
| So what will they use for roads if they run out of
| rubble? It has to come from somewhere?
| aDyslecticCrow wrote:
| Road grit has basically no constraints. They put in
| whatever is cheap to dilute the expensive cement or
| asphalt as much has possible. Old concrete is used
| because it's cheap, not because it's special in some way.
|
| If old concrete can be turned into new cement, that is
| extremely valuable compared to using it as grit.
|
| There are some logistics and energy questions, though.
| Transporting old concrete to the nearest steel plant
| could be too expensive to be worth it. And arc-furnace
| steel plants are still the exception, not the rule.
| kragen wrote:
| old concrete is not in high demand. unfortunately, when i
| try to follow your link it just says 'fuck you, wetback
| scum', like every home depot page, so i'm not sure what
| your evidence is. are they offering you money for your
| old concrete? how much are they paying?
|
| something like 15% of the material that gets carted to
| landfills is old concrete
|
| generally speaking, old concrete is used in new concrete
| as (very) coarse aggregate. alternative coarse aggregate
| is mostly angular crushed stone, like the track ballast
| you see around railroad tracks. this is made by
| dynamiting deposits of limestone, granite, or basalt and
| feeding it through a rock crusher. while this sounds
| violent and energy-intensive, it's nothing compared to
| running a cement clinker kiln. most of the cost of coarse
| aggregate is from the cost of shipping it, not the cost
| of the energy needed to crush it; as wp says
|
| > _Large stone quarry and sand and gravel operations
| exist near virtually all population centers due to the
| high cost of transportation relative to the low value of
| the product. Trucking aggregate more than 40 kilometers
| is typically uneconomical_
| CyberDildonics wrote:
| Every link to homedepot.com calls you a racial slur?
| kragen wrote:
| at greater length, what it says is 'Access Denied You
| don't have permission to access
| "http://www.homedepot.com/c/ah/how-to-dispose-of-
| concrete/9ba..." on this server.', as it always does when
| you access a homedepot.com page from argentina; i
| summarized it for your benefit
| CyberDildonics wrote:
| Home depot left south america in 2001. I think you may be
| hallucinating persecution.
|
| https://vmsd.com/home-depot-leaves-south-america/
| defrost wrote:
| It rejected my advances as a corked hat wearing kangaroo
| chaser ... it appears to be heavily geofenced and
| insular.
| VagabundoP wrote:
| It rejected me like the potato eating stout drinking bare
| knuckle fighter that I am.
| defrost wrote:
| _mar na beidh ar leitheidi aris ann_
| blitzar wrote:
| Can confirm; told me to go shag some sheep.
| szvsw wrote:
| Putting old concrete into roads loses almost all of its
| value and is a pretty atrocious form of downcycling;
| notice that the linked article is literally about
| "disposing" of concrete, not re-using it meaningfully.
| Most of concrete's primary use case is as a structural
| material in buildings/infrastructure - beams, columns,
| slabs, etc, and we unfortunately have very little by way
| of re-using concrete _structurally_ , partly due to
| demolition processes, documentation, rebar etc etc. While
| pre-cast concrete is potentially more up-cyclable, again,
| it's not really designed for disassembly, re-assessment,
| etc, and there are very few actual use-cases/projects
| that have done anything of the sort, though some very
| cool research is being done on this at places like MIT
| and EPFL, including novel pre-cast concrete systems
| specifically designed for dis-assembly and re-use.
|
| Part of what makes the article and methodology linked
| here interesting is that it a) uses waste heat which b)
| is already theoretically able to come from renewable
| sources and c) can be used to to support manufacturing of
| structural components further upstream in the lifecycle
| of cement/concrete.
| colechristensen wrote:
| One of the problems with calculating CO2 emissions from
| concrete is the process involves cooking off the CO2 out of a
| carbonate mineral, but when you actually use it to construct
| something, the chemical reaction to make it involves pulling
| that same CO2 back out of the atmosphere into the concrete as
| it cures. A big chunk of it in the first few days of curing,
| and in theory all the rest in a long tail of curing which
| takes decades (in practice not actually all of it).
|
| So how do you account for this - temporary - CO2 emission
| when doing your calculations?
|
| Often it depends on the story you're trying to tell... lying
| with statistics and all.
| kragen wrote:
| this is true of lime cement, but it is not true of portland
| cement. portland cement absorbs much, much less carbon
| dioxide from the atmosphere than the lime used to make it
| released when it was calcined. (i think the figure i heard
| was 15%?)
|
| this is one of the reasons that green building promoters
| are advocating a return to lime cement for cases where it's
| applicable
| 3abiton wrote:
| What's the catch
| mechhacker wrote:
| Nuclear has a large heat source (or can make a large heat
| source instead of converting to electric first) to do a lot of
| things like this.
| Animats wrote:
| Nope. Nuclear isn't hot enough. Only about 315degC at the
| output end. Electricity, though, has no thermodynamic upper
| limit on what temperature can be generated.
| Dylan16807 wrote:
| That's not a thermodynamic limit, that's a design limit for
| light water reactors.
|
| Molten salt reactors are generally around 700C but they can
| go hotter.
| Animats wrote:
| Steelmaking takes place around 1650C. Getting up to
| molten steel temperatures is hard.
|
| Yes, you could _potentially_ use waste heat from a
| reactor to preheat the tundish, and maybe the scrap and
| ladle. Nucor preheats using natural gas to save on
| electricity. No need to bring everything up from room
| temperature on electric power. A nuclear reactor
| immediately adjacent to a steel caster is probably not a
| great idea.
| bruckie wrote:
| Is there a cost effective way to move that heat to where it
| could be used?
|
| Nuclear reactors can produce very high temperatures, but in
| most reactors the heat is moved to turbines using water. Are
| there ways to move the heat at the high temperatures required
| to melt steel? (AFAIK, even molten salt is too cold.)
| vilhelm_s wrote:
| People have been talking about this since at least the
| 1970s, but no existing reactors have high enough
| temperatures. There are various concepts on paper that
| could do it.
|
| https://world-nuclear.org/Information-Library/Non-power-
| nucl...
| seventyone wrote:
| How does this address the emissions of concrete's curing
| process? There's no way you can have "zero emission concrete".
| I've seen proposed additives that will reduce the emissions
| during the curing process but that chemical reaction is going
| to have to happen regardless.
| bobfromhuddle wrote:
| Concrete absorbs co2 while curing. It's the calcination
| process, where we heat limestone up until the co2 burns off,
| that has unavoidable emissions. Since this concrete is
| recycled, that's already happened.
| kragen wrote:
| see https://news.ycombinator.com/item?id=40461810 for a
| correction
| meindnoch wrote:
| What are you even talking about? CO2 is absorbed during
| curing.
| logtempo wrote:
| It's math time, let's look what wikipedia say about electric
| arc furnace:
|
| - 1.44 gigajoules (0.4MWh) is required for 1 ton of steel. In
| theory.
|
| - 300T of steel needs 132 MWh, and a "power-on time" (the time
| that steel is being melted with an arc) of approximately 37
| minutes.
|
| ---- wikipedia end -----
|
| From https://ourworldindata.org/grapher/electricity-prod-
| source-s...: total world electricity from renewable was
| 10,700TWh in 2021. 11,600 TWh in 2023.
|
| 1.5 billions (metric) tons of crude steel were produced in
| 2023. 30% of it by electric power.
|
| ------------------------
|
| (A) Let's assume that 20% of those 30% already come from
| renewable (which is not the case, anyway). 30x20% is 6%. It
| means 24% of the 1.5 billions tons are looking for renewable.
|
| It means 360 millions of tons needs its green energy.
|
| It means we need to find 360 millions x 0.4MWh = 144 TWh.
|
| If we don't assume (A), we get 152 TWh.
|
| It means we need to dedicate ~1.5% of renewable worldwide
| energy to replace 24% of crude steel "e-production". In
| theory...
|
| We observed +5% of renewable energy production worldwide. If we
| wanted to make the steel *production* go green (1.5*3.33 = 5%),
| in theory it could be possible in one year...in theory.
|
| Tbh, I expected a more crazy conclusion. I'm quite sure the
| number is off by more than 10% though. But even if it was off
| by 100%, it would mean it's possible in 2 years.
|
| On a side note: it's useless anyway if those 5% are not coming
| with a decrease of 5% of coil&gas consumption. Which is not
| what's happening...
|
| Feel free to redo the math, I can make a mistake!
| dr_dshiv wrote:
| > We observed +5% of renewable energy production worldwide
|
| "The amount of renewable energy capacity added to energy
| systems around the world grew by 50% in 2023, reaching almost
| 510 gigawatts (GW), with solar PV accounting for three-
| quarters of additions worldwide, according to Renewables
| 2023" https://www.iea.org/news/massive-expansion-of-
| renewable-powe...
| XorNot wrote:
| A sector can grow by 50% and still be a small fraction of
| the overall mix.
|
| This is in fact the common problem with growth figures:
| going from 0 to 1 unit is literally infinity % growth,
| going from 1 to 2 at the same rate is 100%, but 1 to 3 is
| now only 50% etc...
|
| But you've also got the problem that _capacity_ versus
| _production_ is important to renewable energy in a way
| which doesn 't apply the same to fossil fuels. Build a 1GW
| thermal power plant, you'll get about 0.8GW across the
| year. Build a 1GW solar plant, you'll get 0.1 - 0.25 GW
| across the year. But in terms of _capacity_ you
| theoretically have 1GW, and at times on any given day,
| will.
| Retric wrote:
| Wind and solar supplied 12% of global electricity in 2022
| up from 10% in 2021 and things are still accelerating.
| You can't keep this kind of growth rate up for long
| before things change.
| https://www.cnbc.com/2023/04/12/wind-and-solar-generated-
| a-r...
|
| Your capacity factor numbers are also off ex: 29.7%
| capacity factor averaged over 3 years
| https://en.wikipedia.org/wiki/Mount_Signal_Solar.
|
| Thermal is also much lower than your suggesting. China
| the world's #1 coal consumer has capacity factors under
| 50% because they are using them for load following.
| France's nuclear averaged ~70% for years for similar
| reasons. It's only where the there's excess natural gas
| and minimal solar/wind that thermal can keep high
| capacity factors but that's becoming rare.
| XorNot wrote:
| Grabbing one specific solar install and saying it's
| representative of all solar is absurd. If I take my
| rooftop solar in Sydney and generalize then I'd be saying
| it's 12.5%.
|
| If I go by the CSIRO estimates[1] then that range is a
| reasonable middle for Australia (generally considered a
| sunny country) and would be optimistic for somewhere like
| Germany[2].
|
| You're also misrepresenting capacity factors for thermal
| power plants: a thermal powerplant used to follow load
| operates _below_ it 's maximum capacity factor.
| Renewables _can 't_ follow load - capacity factor is the
| best they can do.
|
| [1] https://www.csiro.au/en/research/technology-
| space/energy/Gen...
|
| [2] https://en.wikipedia.org/wiki/Solar_power_in_Germany
| Retric wrote:
| I'm saying your range was incorrect and it only takes one
| example to show that. But here's another 32.3% using
| single axes tracking:
| https://en.wikipedia.org/wiki/Mesquite_Solar_project. I
| can go over 35%, but the point's clear. In the real world
| roughly half of grid scale solar power is generated from
| plants over 25% capacity factors and sub 15% is mostly
| just outdated solar thermal or very poor locations only
| in use because of subsidies. https://emp.lbl.gov/pv-
| capacity-factors
|
| Thermal power plants pay for fuel and therefore real
| world capacity factors are lower as renewable generation
| increases. I could point to many coal power plants in the
| 40-50% range, but that feels pointless.
|
| Anyway, rooftop solar isn't representative of the grid
| scale solar because it's doesn't use ideal angles for the
| latitude let alone 1 or 2 axis tracking. It's also
| frequently shaded by trees etc. People trying to make
| money selling at wholesale prices just care more about
| efficiency than someone offsetting retail electricity
| rates.
| XorNot wrote:
| You are still not getting it. If someone says "we
| installed 1GW of capacity" then what does that mean?
|
| It means you've either got 1GW of dispatchable generation
| on hand, or some proportionally much smaller amount of
| non-dispatchable generation on hand.
|
| The number doesn't mean anything without correct context
| which was the entire point.
|
| But "dispatchable" is key. _Choosing_ to run a thermal
| powerplant at lower output due to market conditions is
| different to literally being unable to generate energy.
|
| So talking about "X increase in renewables" doesn't tell
| you a thing, which was the entire point I was making.
|
| If you build 100GW of solar then in temperate Australian
| regions it's actually like having 25, in Germany it's
| like having 10, and in the California desert I guess you
| maybe get 40. What you don't get, is 100GW on demand. And
| overnight you get zero.
|
| All of which has a pretty substantial effect on whether
| "installed capacity" can move the needle on total CO2
| emissions because the effect on grid production is much
| less linear then traditional thermal power plants.
| Retric wrote:
| > "we installed 1GW of capacity"
|
| "Wind and solar supplied 12% of global electricity in
| 2022" that's the number I am tracking not how many panels
| they happened to use. Location and other details matter.
| Plopping down Solar in the UK, Germany, or southeastern
| Australia is a poor investment. So no I don't give a fuck
| about hypothetical GW in dumb locations, it's also
| irrelevant to the point I was making.
|
| > can move the needle on total CO2 emissions because the
| effect on grid production is much less linear then
| traditional thermal power plants.
|
| _Batteries + Solar means is more linear than thermal not
| less._
|
| Again just track renewables by kWh over the year not
| simply nameplate capacity if that's what you want to
| know. It's not some secret people actively tack and
| report it as useful information.
|
| As to the rest of your points, market conditions exist
| before you install the power plant. Initially the
| question is wind or solar more useful needs to be
| addressed. Pick solar and many choices remain.
|
| Install solar with 1 or even 2 axis tracking and you get
| more hours per day of generation from the same land and
| panels than fixed installation but higher cost per kWh.
| Install it X miles west and power comes on a little later
| each day. _Add a battery and you can shift supply within
| the day._ People don't just plop down panels randomly
| there's a huge amount of optimization up front to
| maximize long term gains.
|
| Thermal on the other hand has fewer levers, shifting the
| power plants location doesn't help match the demand curve
| and there's no option for cheaper but less reliable
| output. The economics also completely kill the idea of
| having batteries to cover the after work spike in demand
| etc etc. Right now people are trying to decide if they
| want a power plant that's only going to provide 45% of
| hypothetical capacity while still being forced to pay the
| full construction costs. Net result an absolutely massive
| increase in how much wind and solar generation is used
| not just installed each year.
| XorNot wrote:
| > "The amount of renewable energy capacity added to
| energy systems around the world grew by 50% in 2023
|
| Literally the quote I was responding to, with a source,
| before you ran off on this tangent, I presume because you
| can't read.
|
| You've continually failed basic reading comprehension
| here.
| jncfhnb wrote:
| This logic does apply to fossil fuels because fossil fuel
| plants cannot compete on cost with renewables when
| they're running at full capacity. In terms of actual
| production, many fossil fuel plants are running at lower
| than their potential production.
| XorNot wrote:
| That's the entire point: a proportional increase in
| renewables isn't a 1:1 reduction in thermals. You _don
| 't_ replace 1GW of thermal plant capacity with 1GW of
| solar. You replace some fraction of its output, but it
| still runs overnight, or at times of low production or
| whatever.
|
| So installed capacity increasing doesn't directly tell
| you much about the future composition of the grid,
| particularly in the absence of significant storage or
| overnight capable sources like wind (which after still
| variable).
| jncfhnb wrote:
| Well, sort of. You're likely going to use 100% of
| possible production for wind and solar. That's much lower
| than "capacity", true. But you're going to use it.
|
| Fossil fuel sources on the other hand are being rapidly
| downscaled. And if it's not operationally profitable to
| run a gas plant at reduced capacity, the plant will have
| to shut down entirely. This is happening to peaker plants
| due to battery power coming online.
|
| the economics of gas plants become much, much worse
| quickly. The cost of energy from a gas plant that's run a
| small portion of its planned output is much higher due to
| the fixed costs.
|
| This should push up the price of off-renewable time
| power, which will increase the business case for
| batteries. It's a bit of a death loop.
|
| Gas will be here for a long time yet but I predict
| mainstream forecasts are underestimating how quickly the
| tides will turn to the share of renewables
| passwordoops wrote:
| Meaning it increased from 3.3% to 5% in 2023?
| lolinder wrote:
| For some reason that I don't understand, the IEA mostly
| reports the amount of capacity added to energy systems per
| year and the changes in that amount. So that 50% number
| isn't the growth rate of solar PV energy capacity, it's the
| growth rate of the growth rate. OP is talking about the
| growth rate of the percentage of the system that is solar.
|
| It's the equivalent of if they identified something's
| velocity and you tried to contradict them by pointing to
| its acceleration.
| jncfhnb wrote:
| Probably because the base is changing fast enough that
| it's hard to compare percentages of the total population
| over time. Geometric growth is kind of hard to follow.
| logtempo wrote:
| which mean we can produce close to 3000T of steel in a year
| with renewable. (1,888 millions tons were produced in a
| year).
|
| The 5% is for all electric sources. I don't look at
| renewable only but any sources (and coil&gas makes a solid
| 60% of it).
| cpill wrote:
| you don't happen to play factorio do you?
| logtempo wrote:
| I did played to shapez. But I realized it's programming for
| kids and I'm not a kid anymore ahah, so better programming
| for usefull things.
| dukeofdoom wrote:
| Every one has a plan until reality strikes. Or as Mike Tyson
| put so eloquently, "Everyone has a plan until they get
| punched in the mouth."
| jillesvangurp wrote:
| I love math like this. It makes things sound doable. 144 TWH
| is a lot of power. The world produces about 25000 TWH per
| year currently. So, we're talking less than a percent here of
| global electricity generation. Which over the course of the
| next decades is going to shift to be mostly/entirely
| generated by renewables.
|
| This obviously won't happen overnight. But it suggests a few
| long term trends for steel production to move close to where
| renewable power is cheapest and most plentiful. E.g.
| Australia is a renewables power house and exports a lot of
| mined but unrefined materials. Long term it makes more sense
| to produce aluminium, steel, etc. locally instead of
| exporting the ore to China, India, etc. and then re-importing
| it the upcycled materials.
| logtempo wrote:
| Thank you. I actually have to point that 25,000 TWh (I have
| the number of 29 PWh) is electric production only. global
| energy consumption is ~180,000TWh (a drop of 10,000TWh
| during covid, yay!), 85% of it is (c)oil&gas.
| jillesvangurp wrote:
| My numbers might be slightly out of date. It makes sense
| for energy generation to have grown recently.
|
| For oil and gas energy usage, you should take into
| account that usable energy and energy consumption are two
| things. When electrifying, you typically end up needing
| less energy overall. The notion of replacing oil twh with
| solar twh is simply wrong. This is something the IEA gets
| wrong in most of its reports. Which is one reason why
| their estimates and predictions keep having to be
| corrected by them every few years.
|
| A good example is ICE cars vs. EVs. A gallon of gas
| represents about 33.7 kwh of energy. A Tesla can do over
| 4 miles per kwh. Most ICE cars get nowhere near 120 miles
| per gallon. Anything over 1 mile per kwh of gas is
| actually pretty good. Especially for bigger cars. So, an
| ICE car wastes about 70-80% or more of its energy (heat,
| noise, vibrations, friction, etc.). You see the same
| pattern in other sectors where electrifying usually also
| means improved efficiencies. Most Teslas only have 2-3
| gallons worth of kwh in the car. An ICE car with a tank
| that small would have a terrible range.
|
| So, a doubling or tripling of electricity generation
| might actually be good enough to replace most fossil fuel
| usage.
| logtempo wrote:
| You are correct, but conversion from thermal to
| electricity is quite inneficient. and it represent 60% of
| global electricity production. So driving a tesla is more
| efficient IF it comes from renewable.
| ZeroGravitas wrote:
| EVs (and heat pumps) do not require renewable grids to be
| more efficient than ICE cars (and gas boilers)
|
| They are sufficiently more efficient (roughly 4x) than
| even adding the 60% inefficiency of gas turbines and
| electricity transmission, charging losses etc. do not
| destroy their inherent efficiency advantage.
| tonyarkles wrote:
| That's one of the neat things about heat pumps. In my
| province in Canada about 25% of our energy is used as
| electricity and 75% is used as heat. This is ignoring
| cars, looking at residential, commercial, and industrial.
| The majority of our electricity generation comes from
| coal and natural gas, with some hydro and some
| wind/solar. People are very keen to close down the
| polluting power plants but are generally quite quiet on
| the topic of converting our residential and commercial
| heating to electric even though that covers 75% of our
| energy use.
|
| But with heat pumps (backed up by resistive heating since
| we get cold enough to need it), we can still get a win
| there. Natural gas and coal generation can be ~30%
| efficient, but heat pumps can readily have a 4:1 COP or
| better. Even factoring in the inefficient generation of
| electricity we can still heat our homes with net less
| energy and then focus on replacing our electricity
| generation with less polluting sources (eg a mix of
| nuclear baseload, wind+solar+battery, and natural gas as
| a fallback)
| hn_throwaway_99 wrote:
| I loved this, especially because when I read comments that
| start with "It's math time", usually they go on to show how
| some "nice in theory" idea would never scale, but that's the
| complete opposite in this case!
|
| Also, another thing that's good about these types of energy
| intensive industrial operations is they can essentially act
| as a sort of battery - it's a large load on the grid but (I'm
| guessing, someone correct me if I'm wrong) could potentially
| be more flexible with respect to time shifting: if it's a
| bright sunny day, crank up the furnaces to full speed, but if
| it's cloudy, back off. That helps make solar installations
| more economical if there is a good chance something will be
| there to take up extra power.
| logtempo wrote:
| You're correct that the power required is quite big. It's
| actually one of the dead-spot in my comment. Supplying
| 135MWh for 37min is a lot. For example, the Jichuan Solar
| Park - China is "1,000MWh" and 90km^2 wide (I assume the
| number is the optimal output).
|
| So, if we want to produce 1,888 millions tons of crude
| steel with solar panels, and assuming we can supply with
| Jichuan solar park 10 plants producing 300T of steel:
|
| 1,888/3 = 630 steel factory = 630 Jichuan Solar park =
| 56700km2. It's a bit larger than Croatia. For steel only.
| And it's assuming ideal production, only solar panel
| surface...So it could be Ireland actually.
|
| As for the "nice in theory", my small demonstration is
| actually in this ball park, because the other dead-spot is
| that I account for electric production. It represent ~30PWh
| and worldwide consumption of energy is ~180 PWh (85% of
| those are from fossil).
|
| So this 5% increase of renewable energy, of total
| electricity production, is actually swimming in those 15%.
| krab wrote:
| Northern Africa has a lot of cheap land and a lot of sun.
| Wind, too. Steel can be then transported (it is already
| shipped across large distances). You would have to solve
| maintenance, but that should be doable.
|
| The main obstacle for investment is political stability
| and alignment.
| throwup238 wrote:
| There's another catch to your calculation: arc furnaces
| use scrap steel, which is only enough to supply 30% of
| the world's demand at this time. That's why 30% of steel
| is from electrical power. AFAIK most of the furnaces are
| already built in places with plentiful renewable power to
| take advantage of negative power prices. There are
| furnaces in Europe that operate only when the power is
| free.
|
| Most of the world's steel is produced from ore, which not
| only requires three times the energy of recycling scrap
| but also vast quantities of carbon from fossil fuels to
| incorporate into the alloy. I believe there's a
| relatively new electrolytic process for the ore but at
| far smaller scale and it requires even more power.
| organsnyder wrote:
| > 1.44 gigajoules (0.4MWh) is required for 1 ton of steel. In
| theory.
|
| That's actually a lot less than I thought it would be. My
| smallish (6kW) solar system on my garage has generated 20MWh
| in the ~3.5 years it's been operating. I'm sure 50 tons (in
| theory) of steel isn't huge by industrial standards, but
| that's more than I'd expect from a residential array in
| Michigan.
| logtempo wrote:
| It's a little bit more than the energy of a "normal"
| lightning, according to wikipedia^T^M
|
| One of the side problem is energy density. Your garage can
| deliver 6kWh at best, but it can't deliver 12kWh for 30min.
| silverlake wrote:
| The heated metal can act as a battery. Another post on HN
| says they can recover 40% of energy from a heat source over
| 1000C. Seems like everyone wins here.
| Hooray_Darakian wrote:
| > But if solar power keeps doubling every 2 years, we will very
| soon have way more power than we know what to do with
|
| How soon is soon to you?
| https://www.eia.gov/todayinenergy/detail.php?id=50357
| XorNot wrote:
| Also the problem that a sigmoid curve looks exponential if
| you only observe a small part of it[1].
|
| [1] https://www.researchgate.net/figure/Successive-S-curves-
| in-t...
| dr_dshiv wrote:
| All material exponential curves are sigmoids, no? It's a
| question of when things stop accelerating.
| XorNot wrote:
| Of course, but in cases where there's a defined endpoint
| we also know that the decay from the exponential looking
| phase is going to happen well before we get there.
|
| i.e. the solar industry won't start installing solar
| panels at an ever higher rate if the amount of solar
| penetration is almost 100%. In fact the relative value of
| installing panels will decline as we get nearer to it.
| Arguably that's already happened - i.e. power prices
| going negative scrapes a lot of the shine off private
| industry funding them.
|
| Versus say, a natural process where while this might
| happen, the bounds aren't limited by humans making
| economic decisions for themselves (which of course, when
| you think about it also implies dangers in extrapolating
| effects of natural processes like climate change - the
| rate of some downstream parameter going up and looking
| linear and shallow could just be a very large system in
| the middle of moving into an exponential phase which
| extends well beyond our ability to manage it).
| kragen wrote:
| 100% of _what_?
|
| to look at it another way, when will we have so much
| solar energy production that it's hard to find a market
| for more solar energy at costs similar to present plant
| costs? right now a megawatt-hour of solar power costs
| usually about 25 dollars, half to a third of the cost of
| a megawatt-hour of power from coal or oil. the energy
| transition has, roughly speaking, cut the cost of energy
| in half. in sunny places, it's even cheaper. that means
| many energy-intensive industrial processes that were
| previously unprofitable have just become very profitable.
| how will that reshape the economy?
|
| it's hard to say in detail, but clearly, as those ramp
| up, energy demand will increase
|
| if you think the answer is '100% of current world
| electrical generation' or even '100% of current world
| marketed energy consumption' you've imported the implicit
| assumption that this seismic change in the energy market,
| unprecedented since the early days of the steam engine,
| won't reshape the economy _at all_ and won 't increase
| energy demand _at all_. this seems like a very
| implausible assumption
|
| a more plausible endpoint is '100% of the sunlight that
| hits the earth'--once we start approaching that endpoint,
| we'll have problems like oxygen-producing algae dying off
| in the ocean because it's not getting any sun. that
| starts to become a problem at roughly 1000x current world
| marketed energy production, 10 doublings, so, around
| 02050
| dr_dshiv wrote:
| Space is a way to expand solar capture beyond the surface
| area of the earth.
| kragen wrote:
| agreed
| hackerlight wrote:
| The shape of the curve is a bit of a red herring, unless
| additional context is considered. Decay could mean we
| have succeeded in decarbonizing the entire power sector,
| which is a signal of success. Or decay could mean
| California has finally built all the solar it needs but
| no other states are following in California's footsteps,
| which is a signal of failure. Both are instances of decay
| that signify very different situations.
|
| You are correct though that a naive prediction of
| constant doublings is definitely wrong. China is showing
| signs of slowing over the last month due to transmission
| and storage bottlenecks in a few locations. BNEF has an
| article about this.
| dr_dshiv wrote:
| We have 1 TW of installed capacity today. In 6 doublings,
| that is 64 TW. If it doubles every 2-3 years, that's in about
| 20 years.
|
| Thats more power than coal+oil+nuclear today.
|
| https://ourworldindata.org/grapher/installed-solar-pv-
| capaci...
| bufferoverflow wrote:
| According to your own chart, it doubles every 4 years, so
| 24 years.
|
| And it's not guaranteed to double like that.
| ZeroGravitas wrote:
| That's a 2021 prediction for 2050 which has 20% as the main
| reference case (some go up to 27% if gas is expensive, for
| example).
|
| The 2023 prediction updated the reference case to closer to
| 40% in 2050 (again some go higher).
|
| That's a big jump in two years.
| huijzer wrote:
| They fit a linear line to a phenomenon that is currently
| moving exponentially, and has no signs of slowing down.
|
| From 2010: https://youtu.be/MAFoqo3Jbro?si=tg11Iunaclk2L2uH.
| bufferoverflow wrote:
| > _we will very soon have way more power than we know what to
| do with_
|
| Only short term. Humans quickly find ways to use power. There
| are so many energy-intensive tasks, humankind will not have
| enough power for a long time.
|
| You can desalinate water or mine crypto. And if we have robots
| that are comparable to human capability, you can just scale
| production of everything endlessly.
| quaintdev wrote:
| What if we are successful with Nuclear Fusion?
| hackerlight wrote:
| Impact would depend on cost per kWh of the fusion energy
| prawn wrote:
| I imagine we'll be air conditioning bigger spaces and more
| liberally, in a lot of places.
| doikor wrote:
| Arc furnaces are also expensive so realistically you want to
| have one running as close to 24/7 as possible.
| chakintosh wrote:
| > we will very soon have way more power than we know what to do
| with
|
| https://english.aaj.tv/news/330362080/germanys-solar-boom-le...
| ben_w wrote:
| Nice, this was one of the bigger things I have on my "I hope
| someone knows how to solve this" pile.
| mandibeet wrote:
| What else is in that pile?
| dylan604 wrote:
| Creating clean energy with fusion, desalinating salt water
| for near limitless clean water, reducing plastic use, curing
| cancer and on and on and on
| ant6n wrote:
| Black holes, portals, FTL, electoral reform...
| ben_w wrote:
| I do have blog posts about all of those things, but
| that's more my "shower thoughts" pile:
|
| * https://benwheatley.github.io/blog/2022/05/14-17.06.59.
| html
|
| * https://benwheatley.github.io/blog/2021/07/31-13.37.34.
| html
|
| * https://benwheatley.github.io/blog/2017/04/20-14.32.32.
| html
|
| * https://benwheatley.github.io/blog/2024/04/24-10.42.51.
| html
| was_a_dev wrote:
| I like the implication that FTL is closer on the horizon
| than electoral reforms
| ant6n wrote:
| you saw what I did there
| darknavi wrote:
| > desalinating salt water for near limitless clean water
|
| Don't forget the free salt!
| ben_w wrote:
| Agricultural emissions, mostly methane but also land-use.
|
| Metalysis (which exists, I want to see more roll-outs in more
| materials, particularly iron and steel).
|
| At least one of "cheaper storage" or "the political solution
| to create a global power grid that I already know is both
| possible and affordable on paper" (c. 230 bn USD of
| aluminium).
|
| Cheaper solutions to improve the insulation and cooling in
| older buildings.
|
| Industrial scale Sabatier process.
| sandworm101 wrote:
| >>The Cambridge researchers found that used cement is an
| effective substitute for lime flux
|
| So they can only "recycle" this concrete as a substitute
| ingredient during steel making? That cannot scale. We would have
| to start making epically more amounts of steel in order to
| process even 1% of the concrete that we would want to recycle.
| j2bax wrote:
| Is there a reason they couldn't just reuse the same steel over
| and over just to process the cement at scale?
| sandworm101 wrote:
| Lime is used to remove impurities from the melt. So I imaging
| they would have to re-add those impurities each time. I doubt
| that would be energy-efficient.
| dylan604 wrote:
| The industries in the Steel Belt liked your post
| bell-cot wrote:
| Very likely no - so long as electrical power is free-ish.
| Because if they aren't actually producing X units of steel
| along with Y units of cement in each batch, then they'll have
| to pay for the whole thing out of just the cement sale
| revenues.
| zharknado wrote:
| No, they sub it for lime flux, which had the side effect of
| reactivating the cement (makes "clinker"), which can then be
| used again in new concrete.
|
| Pretty cool hack!
| hackerlight wrote:
| How confident are you in your 1% number? Are you sure it's not
| 20% or 50%?
| adolph wrote:
| Seems like the "big if feasible" part is reducing concrete to
| hydrated cement paste.
|
| From actual paper:
| https://www.nature.com/articles/s41586-024-07338-8
|
| _Recovered cement paste (RCP) is not commercially available at
| scale at present. . . . The value of the improved recovered
| aggregates is not at present high enough to cover the extra cost
| of processing, so RCP is currently landfilled. However, the know-
| how and the technologies required to produce RCP at scale exist.
| [22]_
|
| 22. Thermomechanical beneficiation of recycled concrete
| aggregates (RCA):
| https://www.sciencedirect.com/science/article/pii/S095006182...
|
| The cited paper does not support the assertion that tech to
| recycle concrete into RCP exists. The paper discusses removing
| adhered mortar (AM) from recycled concrete aggregate (RCA).
| mandibeet wrote:
| Cement production is a significant contributor to global carbon
| dioxide emissions. Amazing that the development of effective
| cement recycling methods is in process.
| magicalhippo wrote:
| Another way is to build stuff that doesn't have to be torn down
| after 10 years. Quite a lot of large concrete buildings in town
| have been torn down less than 20 years, some just 10.
|
| Seems quite wasteful, surely there's a better way with some
| planning and foresight.
| hcarvalhoalves wrote:
| ... or already build planning for tear down. Steel and wood.
| magicalhippo wrote:
| Yea that's what I was thinking of. Either switch materials or
| build with future use in mind.
|
| We've recently gotten a fairly large wooden tower[1] here in
| Norway, will be interesting to see how it fares in this
| regard.
|
| [1]: https://www.architecturaldigest.com/story/worlds-
| tallest-tim...
| card_zero wrote:
| Nice. That's only 5 feet shorter than the (steel-framed)
| Flatiron Building.
| forgotusername6 wrote:
| This is terrifying from a fire safety point of view. Does
| Norway have rescue ladders that can reach the top of that
| building?
| actionfromafar wrote:
| Counter-intuitively, wooden buildings when properly
| designed are not especially dangerous from a fire safety
| point of view.
| lesuorac wrote:
| I think intuitively, properly designed things are well
| designed.
| cultofmetatron wrote:
| I'm a huge fan of cross laminated timber myself. Its really
| made for a closed loop economy. carbon neutral and a great
| fit for local production of building materials.
| thangalin wrote:
| https://www.construction-physics.com/p/how-to-design-a-house...
| onlypassingthru wrote:
| It may not be a panacea, but using busted up chunks of concrete
| in gabions is a great way to re-use an otherwise worthless
| material. For those who don't like the aesthetic of _post-
| industrial wasteland_ , just use the concrete chunks in the
| interior of the gabion and put the pretty rocks on the exterior
| faces so that no-one will ever know your beautiful gabions are
| filled with demolition debris.
| ksenzee wrote:
| But the point of the article is that used concrete is no longer
| a worthless material, because it can now be recycled, which
| avoids the huge carbon impact of manufacturing new concrete.
| jgord wrote:
| Nice to see this topic survive the flagging process on HN..
|
| Would be great to have a discussion of some other promising non-
| carbon energy sources, such as drilled geothermal.
|
| Slightly off-topic - gen pop are often surprised when I mention
| that NET-ZERO == MAX-CO2 == MAX-HEAT. People often assume that
| getting to net-zero is 'mission accomplished' .. but its the area
| under the curve that counts, the total CO2/GHG equiv put up
| there, as it stays around for a long time.
|
| If we are nearing +1.5C today, with temp rising at around 0.25C
| to 0.3C per decade, at current long plateau of max emissions.. we
| will likely be somewhere in range +2.5C to +3.0C by the time we
| reach net-zero, possibly by 2050.
|
| I'm not sure that +2.5C is survivable for large human populations
| .. hence the above concerns prompt one to look at things like SRM
| - putting up sulphur particulates to increase cloud cover, so
| less sunlight is absorbed by the oceans, exerting a net cooling
| effect [ as we did with container shipping fuels until recently -
| until the fuel was mandated to contain less Sulphur ]
|
| IMHO, we engineered our way into this mess by geo-engineering a
| CO2-rich hot biosphere, and we will need to engineer our way out
| of it - it could be worse, we seem to have a lot of technologies
| that can replace carbon-fuel and store energy and arguably reduce
| heat.
| consumer451 wrote:
| I agree that we may require sulfur injection, but it needs to
| be strictly tied to two things:
|
| 1) Compulsory reduction in CO2, methane, etc. SRM is just
| kicking the can down the road. It cannot be band aid for more
| pollution.
|
| 2) The system needs guaranteed constant funding, as again, it's
| kicking the can down the road. If you suddenly stop SRM after
| 20 years, you get 20 years of climate change increase all at
| the same time.
|
| Also, it needs the greatest diplomatic push in human history to
| get nearly every country on-board with the plan. All countries
| will be affected by this. Without buy-in, it could lead to
| conflict. For example, Russia is looking forward to higher
| temps and a longer crop growing season.
| robertlagrant wrote:
| Why would it be stopped by a flagging process?
| japanuspus wrote:
| They replace the flux used in steel recycling with used concrete,
| and instead of useless slag they get recycled cement.
|
| This is a really good idea, but it is important to keep in mind
| that even if all of the steel production in the world (~100
| Mton/y) shifted to this method, it would only have a negligible
| impact on the cement production (~ 4 Gton/y).
| philipkglass wrote:
| Are you looking at a single country's production instead of
| global production?
|
| https://www.statista.com/statistics/267264/world-crude-steel...
|
| _In 2022, a total of around 1.9 billion metric tons of crude
| steel were produced worldwide._
|
| EDIT: however, your intuition that the impact on cement
| production would be tiny is correct.
|
| This report indicates that producing new steel from ore
| requires about 270 kg of limestone per metric ton of steel, or
| 88 kg of limestone when recycling steel in an electric arc
| furnace:
|
| https://worldsteel.org/wp-content/uploads/Fact-sheet-raw-mat...
|
| World steel production is about 35% recycled, 65% new from ore.
| So this new Cambridge research, which applies to recycled
| steel, could displace about 59 million metric tons of limestone
| consumption. That is small compared to billions of tons of
| global cement consumption. It might be locally significant for
| municipalities that have electric arc furnaces for steel
| recycling.
| atoav wrote:
| I really appreciate all technical solutions to our battle against
| climate change. Yet I fear all these gains are without any value
| as long as any increase in efficiency is eaten by our economies
| relianze on constant growth.
|
| This is the root climate challenge as it drives all the
| incentives to exceed our energy/CO2-budgets. Turns out we are
| witnessing what happens when you run exponentially growing
| feedback into the logistic function.
|
| Many are sceptical whether we can solve this capitalism-problem
| without fundamental changes to the system, that would leave you
| with a system that is no longer about capital. I am convinced
| there are many ways to solve that, but first we have to
| acknowledge the driving force behind climate change isn't
| technology, it is the need to grow markets and populations.
| dr_dshiv wrote:
| Most market problems are solved with market solutions, for the
| record. I've always been surprised at this logic. And when the
| market isn't sufficient, we regulate. Why so many
| environmentalists believe we need revolutionary approaches is
| beyond me.
| arrosenberg wrote:
| The market has ignored the problem for over 50 years, while
| stripping the government of its capacity to regulate
| effectively. Many people are pessimistic its going to
| suddenly, spontaneously fix itself.
| dr_dshiv wrote:
| Half of the world's largest companies have committed to net
| zero. Maybe there is more nuance than you are describing?
| https://zerotracker.net/analysis/new-analysis-half-of-
| worlds...
| atoav wrote:
| Within their corp? Or throughout their whole supply chain
| + peripherals?
|
| Is their cleaning contractor also net zero?
|
| With promises like these the devil is in the details. You
| could have one true in spirit net zero company on the one
| side and another net zero shell company that has 1000
| crazy polluting sub-contractors.
|
| Given the fact that many big corps can't even prevent
| child and slave labor within their supply chain, I have
| to say I believe it when I see it.
| dr_dshiv wrote:
| I think the lack of child labor is a great example of the
| market working pretty well -- and getting better over
| time. Perfect is the enemy of the good and all that.
| fnordian_slip wrote:
| >I think the lack of child labor is a great example of
| the market working pretty well[...]
|
| This is a rather unique perspective, I think. Maybe I'm
| missing something, but isn't the decline of child labor
| mostly due to laws? I'd say the constant stream of child
| labor scandals implies that the market is a force
| opposing the protection of children more often than not.
| dr_dshiv wrote:
| The data seem to suggest that the reduction in child
| labor is due to increased wealth and prosperity. I'm not
| saying regulations aren't important--they are. But
| markets increase wealth -- and wealth reduces child labor
| and increases concern for the environment.
|
| https://ourworldindata.org/child-labor
| arrosenberg wrote:
| Thats just a "commitment" - not in any sense an
| achievement. That its only half, at this late hour,
| rudely betrays how badly the market is failing to solve
| this problem.
| atoav wrote:
| Sure. Can you point me to any market solution for capitalisms
| need for exponential growth in a limited resource world?
|
| As I said I have no hard opinions on the fix this needs. But
| it needs to _credibly_ needs to address the core problem. I
| have yet to see a market solution that does that instead of
| say, selling yet another product.
|
| Regulation is another thing. I believe it could really
| deliver a fix. But so far it it seems a true regulatory fix
| will come only after the cost of climate collapse is paid by
| the people who extract money from the system (and by that
| time we will have passed multiple points of no return and
| seen untold pain and suffering by those people who do not
| benefit of this capital).
|
| If you're against revolutions, I'd argue you should be for
| _strong_ regulatory measures that should have happened
| yesterday.
| dr_dshiv wrote:
| Why is it a limited resource world? Why do you conceive of
| growth as requiring coal or land? Why can't growth be
| growth in wellbeing or health or satisfaction? Thus, why
| can't we continue to grow indefinitely?
|
| Isn't time and attention the only limit?
|
| Here's a brief history of capitalism: Running out of
| whales? Develop ground oil. Running out of elephant tusks?
| Develop plastics. Running out of intact forests? Develop
| carbon markets. Earth running hot? Cool it down. Too much
| carbon? Develop renewables. It's all happening. Not at the
| pace you want -- but do you really want to trust that a
| revolutionary new economic governance would deliver these
| outcomes as quickly or efficiently?
|
| I agree that "the point of no return" is a real risk --
| thawing permafrost and all that. But this is why we need to
| figure out geoengineering rather than banning the science
| of it. We can't be so romantic as to think that we should
| leave nature untouched. We are nature and it is our
| existential need to figure out how to sustain ourselves. I
| think progress has been fantastic. It's all happening-- we
| just need a bit more time for the energy and AI transitions
| to happen.
|
| I believe that this optimism is both rationally founded --
| and probably critical for creating a shared social vision
| for positive outcomes. We need to know where we are going
| -- and man, it looks good! There will be so many resources
| to support all human needs -- and even most human desires.
| Let's not break things.
| vouaobrasil wrote:
| It's not happening at any pace. CO2 is going up like it
| always was. No dent. We need to destroy society, not
| develop more technology.
| atoav wrote:
| > Why is it a limited resource world?
|
| That is probably a more profound question than you might
| think. But one answer is, because we are in the
| saturation area of the logistical curve. Just like the
| feedback of a guitar amp infinitly amplifying itself,
| there is a point where it won't get any louder as you run
| into the physical limits of its electrical components,
| changing the sound of everything fundamentally.
|
| We are limited because our earth is a globe with a
| atmosphere so thin, if you scaled the earth down to the
| size of an apple its peel would be way thicker than the
| Earth's. It is limited for the same reason my living room
| is limited: It has a certain geometric extent and that's
| it.
|
| Let's say I put stuff into this room. If my goal was to
| put 5% _more_ stuff into that room _each_ week you
| probably would angle your head and ask me if I was crazy.
| Rightfully so.
|
| Now my point was precisely this: growth sucks as an
| organizing principle in a world of limited resources. It
| would be better to figure out how to make use of the
| resources in a better way. Ans we even know how to do
| this on a smaller level.
|
| But somehow we ended up with a ruling class that well..
| doesn't profit from extracting value from putting more
| stuff into the room, so we do just that.
| vouaobrasil wrote:
| Perhaps because the CO2 curve so far has not reduced is
| growth at all. Perhaps because species are dying right now,
| going extinct because of us. Perhaps because all regulation
| does is improve lives of people in the short-term but does
| not protect the environment. Tell the dead species that
| regulation is effective.
| dr_dshiv wrote:
| CO2 curve in the USA is going down:
| https://ourworldindata.org/co2/country/united-states
| DeathArrow wrote:
| How costly is it? How much energy is it going to consume? Aren't
| most concrete carbon emissions due to energy consumption?
| froh wrote:
| > Aren't most concrete carbon emissions due to energy
| consumption
|
| nope. about 1/3 is from energy consumption, 2/3 are due to the
| chemical processes involved
|
| see Figure 1 here:
|
| https://www.umweltbundesamt.de/sites/default/files/medien/14...
|
| the consumed energy is electricity (Wind or Photovoltaics),
| which is cheap, see sibling comments and plenty (also see
| sibling comments)
| Roark66 wrote:
| This is a very cool discovery, but it's not like "used cement"
| ends up in landfills today.
|
| Most cement ends up as concrete.
|
| Crushed concrete of various sizes is a valuable aggregate used as
| a cheaper alternative to crushed stone for road building etc.
|
| In my area any time I see an ad selling crushed concrete it's
| gone by the time I ring. Perhaps because we have clay and sand
| soils around here there is a permanent shortage of such things.
| onthecanposting wrote:
| It's common practice here to take demolished concrete from a
| structure and pavement and use it as structural fill for new
| development. Sometimes on the same property. Some agencies will
| not allow contractors to haul it off as it has salvage value.
|
| Concrete rubble is also salvageable on the job site. Recycling
| would require transporting to a mill, crushing, separating,
| transporting to a furnace, and then the process described in
| the article starts.
| ThinkBeat wrote:
| This should be adopted slowly over time to learn more about the
| real life consequences. There may be no negatives, or there might
| be something significant.
|
| It may take 10 - 30 years to observe changes. and if all is well
| it can be adopted at scale and/or possible problems detected can
| be mitigated.
|
| Move fast and break things is not a real way to approach climate
| change.
| thatswrong0 wrote:
| I think potentially breaking buildings is less important than
| definitely breaking the environment.
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