18 ms·
Cement recycling method could help solve one of the big climate challenges
- gnabgib 2y agoThere was some discussion yesterday [0] (21 points, 4 comments) [0]: https://news.ycombinator.com/item?id=40446764 https://news.ycombinator.com/item?id=40446764
- dr_dshiv 2y agoIncredible! 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 2y agoOften 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 2y agoIANAMetallurgist. Arc furnaces for steel making already rely on cheaper off peak power, so utilization is already a factor.
- s1artibartfast 2y agoI 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 2y agothe normal kind of arc furnaces are shut down many times a day; it's a batch process, not a continuous one
- s1artibartfast 2y agoDo 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 2y agotripling 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 2y agodon'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 2y agoThey 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 2y agoYou 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.
- Gibbon1 2y agoThis 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-california/ 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 2y agoDid 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 2y agoyou 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 2y agoGreat 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 2y agoWhat about tankless water heaters? You can eliminate greenhouse gas emissions for heating and be more efficient with energy usage overall.
- kragen 2y agoi 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 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 https://www.youtube.com/watch?v=eZRuVEfxIVI in that particular case they say it runs 24/7
- UberFly 2y ago"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 2y agoit'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
- roughly 2y agoThe 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 2y agoCall Mark Cuban, make the investments now!
- pjc50 2y agoCalifornia 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 2y agoThe 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 2y agoOnce 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 2y agoI 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 2y agoHome 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/9ba683603be9fa5395fab90139b31d64 https://www.homedepot.com/c/ah/how-to-dispose-of-concrete/9b...
- s1artibartfast 2y agoI 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.
- 3abiton 2y agoWhat's the catch
- mechhacker 2y agoNuclear 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 2y agoNope. Nuclear isn't hot enough. Only about 315°C at the output end. Electricity, though, has no thermodynamic upper limit on what temperature can be generated.
- Dylan16807 2y agoThat'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 2y agoSteelmaking 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 2y agoIs 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 2y agoPeople 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-nuclear-applications/Industry/Nuclear-Process-Heat-for-Industry https://world-nuclear.org/Information-Library/Non-power-nucl...
- seventyone 2y agoHow 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 2y agoConcrete 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 2y agosee https://news.ycombinator.com/item?id=40461810 https://news.ycombinator.com/item?id=40461810 for a correction
- meindnoch 2y agoWhat are you even talking about? CO2 is absorbed during curing.
- logtempo 2y agoIt'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-stacked 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 2y ago> 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-power-opens-door-to-achieving-global-tripling-goal-set-at-cop28 https://www.iea.org/news/massive-expansion-of-renewable-powe...
- XorNot 2y agoA 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.
- Hooray_Darakian 2y ago> 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 https://www.eia.gov/todayinenergy/detail.php?id=50357
- XorNot 2y agoAlso 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-technological-development-The-dotted-line-shows-the-overall_fig2_340525808 https://www.researchgate.net/figure/Successive-S-curves-in-t...
- dr_dshiv 2y agoAll material exponential curves are sigmoids, no? It’s a question of when things stop accelerating.
- XorNot 2y agoOf 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 2y ago
- bufferoverflow 2y ago> 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 2y agoWhat if we are successful with Nuclear Fusion?
- hackerlight 2y agoImpact would depend on cost per kWh of the fusion energy
- prawn 2y agoI imagine we'll be air conditioning bigger spaces and more liberally, in a lot of places.
- doikor 2y agoArc furnaces are also expensive so realistically you want to have one running as close to 24/7 as possible.
- chakintosh 2y ago> we will very soon have way more power than we know what to do with https://english.aaj.tv/news/330362080/germanys-solar-boom-leads-to-negative-energy-prices https://english.aaj.tv/news/330362080/germanys-solar-boom-le...
- CatWChainsaw 2y agoJevons Paradox will take care of any surplus created.
- ben_w 2y agoNice, this was one of the bigger things I have on my "I hope someone knows how to solve this" pile.
- mandibeet 2y agoWhat else is in that pile?
- dylan604 2y agoCreating clean energy with fusion, desalinating salt water for near limitless clean water, reducing plastic use, curing cancer and on and on and on
- ant6n 2y agoBlack holes, portals, FTL, electoral reform…
- ben_w 2y agoI 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/2022/05/14-17.06.59.html • https://benwheatley.github.io/blog/2021/07/31-13.37.34.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/2017/04/20-14.32.32.html • https://benwheatley.github.io/blog/2024/04/24-10.42.51.html https://benwheatley.github.io/blog/2024/04/24-10.42.51.html
- was_a_dev 2y agoI like the implication that FTL is closer on the horizon than electoral reforms
- ant6n 2y agoyou saw what I did there
- sandworm101 2y ago>>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 2y agoIs there a reason they couldn't just reuse the same steel over and over just to process the cement at scale?
- sandworm101 2y agoLime 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 2y agoThe industries in the Steel Belt liked your post
- deleted 2y ago[deleted]
- bell-cot 2y agoVery 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 2y agoNo, 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 2y agoHow confident are you in your 1% number? Are you sure it's not 20% or 50%?
- adolph 2y agoSeems 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 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/S0950061821029445?via%3Dihub 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 2y agoCement production is a significant contributor to global carbon dioxide emissions. Amazing that the development of effective cement recycling methods is in process.
- magicalhippo 2y agoAnother 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 2y ago… or already build planning for tear down. Steel and wood.
- magicalhippo 2y agoYea 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-timber-framed-building-finally-opens-doors https://www.architecturaldigest.com/story/worlds-tallest-tim...
- card_zero 2y agoNice. That's only 5 feet shorter than the (steel-framed) Flatiron Building.
- forgotusername6 2y agoThis is terrifying from a fire safety point of view. Does Norway have rescue ladders that can reach the top of that building?
- actionfromafar 2y agoCounter-intuitively, wooden buildings when properly designed are not especially dangerous from a fire safety point of view.
- lesuorac 2y ago
- onlypassingthru 2y agoIt 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 2y agoBut 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.
- deleted 2y ago[deleted]
- jgord 2y agoNice 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 2y agoI 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 2y agoWhy would it be stopped by a flagging process?
- jgord 2y ago
- japanuspus 2y agoThey 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 2y agoAre you looking at a single country's production instead of global production? https://www.statista.com/statistics/267264/world-crude-steel-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-materials-2023.pdf 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 2y agoI 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 2y agoMost 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 2y agoThe 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 2y agoHalf 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-largest-companies-are-committed-to-net-zero# https://zerotracker.net/analysis/new-analysis-half-of-worlds...
- atoav 2y agoWithin 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.
- DeathArrow 2y agoHow costly is it? How much energy is it going to consume? Aren't most concrete carbon emissions due to energy consumption?
- froh 2y ago> 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/1410/publikationen/2022-01-04_climate-change_02-2022_decomposition_of_co2_emissions_in_the_european_cement_sector_0.pdf 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 2y agoThis 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 2y agoIt'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 2y agoThis 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 2y agoI think potentially breaking buildings is less important than definitely breaking the environment.
- Slava_Propanei 2y ago[dead]