Researchers Develop System That Transforms CO2 Into Concrete (ieee.org) 76
An anonymous reader quotes a report from IEEE Spectrum: A team from the University of California, Los Angeles, has developed a system that transforms "waste CO2" into gray blocks of concrete. In March, the researchers will relocate to the Wyoming Integrated Test Center, part of the Dry Fork power plant near the town of Gillette. During a three-month demonstration, the UCLA team plans to siphon half a ton of CO2 per day from the plant's flue gas and produce 10 tons of concrete daily. Carbon Upcycling UCLA is one of 10 teams competing in the final round of the NRG COSIA Carbon XPrize. The global competition aims to develop breakthrough technologies for converting carbon emissions into valuable products.
The UCLA initiative began about six years ago, as researchers contemplated the chemistry of Hadrian's Wall -- the nearly 1,900-year-old Roman structure in northern England. Masons built the wall by mixing calcium oxide with water, then letting it absorb CO2 from the atmosphere. The resulting reactions produced calcium carbonate, or limestone. But that cementation process can take years or decades to complete, an unimaginably long wait by today's standards. "We wanted to know, 'How do you make these reactions go faster?'" Gaurav Sant, a civil engineering professor who leads the team, recalled. The answer was portlandite, or calcium hydroxide. The compound is combined with aggregates and other ingredients to create the initial building element. That element then goes into a reactor, where it comes in contact with the flue gas coming directly out of a power plant's smokestack. The resulting carbonation reaction forms a solid building component akin to concrete. The UCLA system is unique among green concrete technologies because it doesn't require the expensive step of capturing and purifying CO2 emissions from power plants. Sant said his team's approach is the only one so far that directly uses the flue gas stream. The group has formed a company, CO2Concrete, to commercialize their technology with construction companies and other industrial partners.
The UCLA initiative began about six years ago, as researchers contemplated the chemistry of Hadrian's Wall -- the nearly 1,900-year-old Roman structure in northern England. Masons built the wall by mixing calcium oxide with water, then letting it absorb CO2 from the atmosphere. The resulting reactions produced calcium carbonate, or limestone. But that cementation process can take years or decades to complete, an unimaginably long wait by today's standards. "We wanted to know, 'How do you make these reactions go faster?'" Gaurav Sant, a civil engineering professor who leads the team, recalled. The answer was portlandite, or calcium hydroxide. The compound is combined with aggregates and other ingredients to create the initial building element. That element then goes into a reactor, where it comes in contact with the flue gas coming directly out of a power plant's smokestack. The resulting carbonation reaction forms a solid building component akin to concrete. The UCLA system is unique among green concrete technologies because it doesn't require the expensive step of capturing and purifying CO2 emissions from power plants. Sant said his team's approach is the only one so far that directly uses the flue gas stream. The group has formed a company, CO2Concrete, to commercialize their technology with construction companies and other industrial partners.
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Why is this modded up??
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Because on Slashdot these days we take anything we don't understand for granted as long as its posted with outrage, is pedantic to the point of stupidity, and yet somehow pretends to sound legit.
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Sigh. It's true.
other inputs (Score:3)
Re:other inputs (Score:4, Informative)
Calcium hydroxide is made from combining calcium oxide and water. Calcium oxide is made from limestone, and the world produces about 170 million tons a year currently.
Other traditional uses of calcium oxide:
cement making (in different processes)
illumination (heat to sufficient temperature and it glows - limelights)
glass doping
food additive
cheap and widely available alkali for chemistry applications
already used in fossil fueled power plants for desulfurization of flue gasses
Re:other inputs (Score:5, Informative)
Limestone: CaCO3
CaCO3 -> CaO + CO2
At best it is neutral, but if If you produce CO2 to generate the energy necessary to make this reaction, it's clearly negative in terms of CO2. You need to find a way to get CaO from something else than Limestone to do something interresting from this reaction.
Re:other inputs (Score:4, Interesting)
You need to find a way to get CaO from something else than Limestone to do something interresting from this reaction.
Use basalt, it's everywhere. It's probably a bit too rich in MgO in many cases but for the most part it's just sand and lime once ground up. Maybe they can get the CaO they need from recycled drywall.
https://en.wikipedia.org/wiki/... [wikipedia.org]
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The problem isn't the magnesia present in basalts, it is that both the magnesia and lime "nominal" components are already combined on a molecule-by-molecule basis with silica units to make magnesium (and calcium) SILICATE minerals. To make the lime (or magnesia) available to interact with carbon dioxide, you need to separate the calcium (magnesium) ions from the silica structures. And that requires a lot of energy.
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Calcium compounds in rocks naturally absorb CO2, as you describe. It's an important natural carbon sequestration route, and the reason CO2 levels tend to drop during epochs of mountain building.
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The solubility of silica in near-neutral water (pH 6-9) is down in the
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I think you forgot to state your thesis, or a conclusion?
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This sort of story comes around every year or three, typicall
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Yes, and I replied that weathering of calcium compounds in rocks is an important carbon sequestration method, a statement with which you appeared to agree. There are other places to get calcium than limestone.
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Calcium oxide is made from limestone
Isn't their goal to MAKE limestone as a result? Please tell me we aren't turning limestone into Calcium oxide just to use it on emissions to turn it back into limestone.
Re: other inputs (Score:1)
Thatâ(TM)s sure what it sounds like, and the calcine process requires huge amounts of energy.
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You might (MIGHT!) be able to extract benefit from the process by capturing the concentrated CO2 from your limestone-to-lime kiln and bottling it, then using the lime to capture the diffuse CO2 in your flue gases (about 80% N2, 9%CO2 and 9% O2, traces argon, quite a bit of water vapour), and then re-bury it as "artificial limestone". But there are several high-temperature processes in there, and it's very likely to need a significant input of energy.
It may be
Slaked lime from a kiln (Re:other inputs) (Score:5, Informative)
The other major ingredient is portlandite, also known as slaked lime. Once you see the primary source of this slaked lime you will see that this is just a scam for carbon capture credits. This just speeds up a process of CO2 capture that happens in every cement, capturing the same amount of CO2 released in making the slaked lime.
https://en.wikipedia.org/wiki/... [wikipedia.org]
To answer your question, slaked lime is an ingredient that is inexpensive but very energy intensive. Inexpensive because the energy comes from whatever is cheap to burn. Coal, used motor oil, natural gas, wood, old paint, grandpa's old Playboy magazines, whatever. Limestone is everywhere and it's a relatively soft rock that is easy to mine.
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Then point out where the next lime stone is in your environment. ... not really "everywhere".
The next to my place is close to 100km
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Then point out where the next lime stone is in your environment. The next to my place is close to 100kmÂ... not really "everywhere".
It's in my toothpaste, foundation of my house, the stone wall behind my house. The road and sidewalk in front of my house. Um, yeah, it's everywhere.
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It's in my toothpaste, foundation of my house, the stone wall behind my house. The road and sidewalk in front of my house. Um, yeah, it's everywhere. ...
That is not a sign of IQ
So you don't mind if I mine your house for my limestone/concrete factory?
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I moved about 130km closer to the nearest limestones a few years ago, but I'm still 20-30km from the nearest ones - and they're not exactly "clean" enough to be suitable for calcining.
There is often a subtext to this : "it is everywhere" is frequently a short form for "it isn't terribly rare, but there is none near where I live, so I can safely propose this without fear that it will ever turn up on my doo
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"I am stupid because I quote Randian fantasies as if they are fact. I quote Randian fantasies as if they are fact because I'm stupid."
FTFY
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Not likely. The real issue is that making concrete the normal way puts a LOT of CO2 into the atmosphere.
According to EPA, between 900 and 1100 kg (1984 and 2425 lbs) of CO2 is emitted for every 1000 kg (2205 lbs) of portland cement produced in the U.S.
Concrete production is responsible for about 1.5% of C02 emissions in the US. If we can turn that negative, it's a huge difference, even if it is slightly more expensive.
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If we can even just make it carbon neutral, that's a big benefit.
What's great about this is that they're just using flue gas too! No fancy scrubbing and processing, just pump the waste gas from burning fossil fuels over the mixture and you get concrete.
That said, I'm a little skeptical, because flue gas has all sorts of nasty chemicals in it. I'm wondering just how safe this concrete really is. Even if it only off-gasses a tiny fraction of a percent of what it absorbed, if you're in the basement of somethin
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If that is true (I don't care one way or the other) then this means that imports of Portland cement (other classes and grades of cement are available) to the US are a significant megatonnage annually, allowing the US to effectively export some of it's carbon footprint to whichever countries made that cement.
Re:other inputs (Score:5, Informative)
"Portlandite" is just the mineral name for calcium hydroxide, the common name of which is "slaked lime". Concentrated portlandite deposits are rare, but they occur all over the world. But rather than create yet *another* mineral resource to fight over, the logical place to look for slaked lime is recycling calcium oxide from old concrete. The binder used in concrete is Portland cement, which is mostly CaO by weight. CaO is the feedstock for the industrial production slaked lime:
Recovering the old concerete and processing it obviously takes energy, but so does mining limestone; and the process of transforming that into Portland cement is a doozy. You almost couldn't design a worse process from a carbon footprint standpoint. You bake your crushed limestone in a kiln at 1100 F to "decarbonize" it (take out CO2 which you dump into the air), then finish off by sintering the enormous mass of crushed stone in your kiln at 2600F.
Of course that's a long way figuring out all the pieces you need, you've got to figure where everything else that goes into the process comes from and ultimately goes to. But before you worry about that, you have to confirm a practical process exists for capturing the CO2. This thing is just about one step up from a benchtop experiment. It appears to produce ten tuns *concrete* (not *cement*) a day; that's just about enough to pour a foundation for a 12 x 12 foot shed.
Then they can put it into old coal mines! (Score:4, Interesting)
Re:Then they can put it into old coal mines! (Score:5, Interesting)
Or we could use it to build shit we need instead of mining even more materials to make traditional concrete, producing more CO2 in those processes (and in the setting of that concrete)
Even if it needs to be pre-cast when it's made, we could make a shitload of highway divider rails, paver blocks, and highway bridge segments with this kind of thing.
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Actually, that was one of Biden's doddering ideas.
(Laying the groundwork for the Rust-language belt when they get displaced again.)
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Re:Then they can put it into old coal mines! (Score:4, Informative)
I thought all the coal miners learned to code?
You're thinking of the con artist who said he'd make coal great again [slashdot.org]:
“President-Elect Trump promised on the campaign trail to put coal miners back to work, and I believe the Trump Administration will do everything they can to make good on that promise,” Roe, R-Tenn., said in a emailed statement. “As I’ve said time and time again, I support an all-of-the-above energy policy, and I strongly believe that should include our most abundant energy source, coal. I’ve seen firsthand what the Obama Administration’s war on coal has done to coal country, and I stand ready to work with President-Elect Trump to bring good paying jobs back to our region.”
Meanwhile, in the realm of reality, coal mining companies keep going bankrupt [time.com] and the same uneducateds who believed the con artist the first time will once again go out in November and vote for him because those "liberal" Democrats want to shut mines down.
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I'm dead you mentioned the realm of reaity. In March 2016, at a Democratic town hall in Ohio, Hillary Clinton said, “We're going to put a lot of coal miners and coal companies out of business.” She later said that she regretted saying that, calling it one of the worst mistakes of her campaign. She even devoted an entire chapter of her book "What Happened", to that gaffe. However you might want to look at it, it certainly looks like a Democrat wanting to shut coal mines down, and undoubtedly conv
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LOL, actually I was glad, not dead. I need another cup of coffee.
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So what you're saying is people were so afraid coal mines might be shut down they voted for someone who hasn't done anything to stop coal mines from being shut down.
Sort of like how people were so afraid of electing a New Yorker who would spend all their money they elected a New Yorker who is spending all their money.
Re: Then they can put it into old coal mines! (Score:1)
Re: Then they can put it into old coal mines! (Score:4, Interesting)
I'm not sure why that concept is so hard to understand or why Liberals are so derisive towards people who made such a choice.
A) I'm not a "liberal". Try conservative.
B) This is why they're called uneducated. They were conned into believing the world would end if a Democrat was elected so they voted someone in who is worse.
C) These uneducateds, despite being lied to, having an "easily" winnable trade war devastate farmers and put them on welfare, have mines closing left and right, will once again, because they'll be conned into believing the world will end if a Democrat gets in office, vote in the same guy whose lies have put them in this situation.
D) That's why people, in general, are derisive to these people. Time and again these morons, and yes, that is the correct word, get hammered when their guy gets in office and yet keep voting these same people in because they are too stupid to face reality. Thus the proverb: The forest was shrinking but the trees kept voting for the axe as its handle was made of wood and they thought it was one of them.
Missing the point entirely. (Score:3)
That proposed solution = more pollution. (Score:2)
When you bury good concrete (in such high demand sand theft is a global problem!) that concrete doesn't go into infrastructure. Other concrete produced by (highly) polluting processes must expensively (in energy and collateral pollution) take its place which is terribly polluting.
The beauty of sequestering CO2 in construction is you don't merely sequester the gas but reduce production pollution footprint. Concrete is a magnificent building material in an age of global warming IF it can be produced in a carb
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When you bury good concrete (in such high demand sand theft is a global problem!) that concrete doesn't go into infrastructure. Other concrete produced by (highly) polluting processes must expensively (in energy and collateral pollution) take its place which is terribly polluting.
Not to mention that it's never going to be as efficient as just not digging up fossil fuels to begin with.
If the tech takes off Australians could build durable, fireproof (not merely fire-resistant) concrete homes and businesses requiring far less energy to cool.
That's already possible to do, and doesn't require this technology. And yet, nobody (save the one dude you posted a link to) really does it. Why? Because concrete is ugly, hard to work with, and extremely heavy.
Concrete is utilitarian, and most people don't want that to describe their house.
People want to describe their house as elegant, bright, light, airy, etc. For concrete houses to take off in most
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Hm? All of the light airy houses I've seen have been made of concrete and steel. Traditional wood frame building doesn't have the strength to create the big windows and unsupported ceiling spans. You CAN do that with wood, but we don't usually.
In the tropics, people tend to build by piling up concrete blocks, then plastering them over. Those are the light airy buildings overlooking oceans that North Americans lust over.
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How did you get this far in life without seeing houses before?
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Sure man.
https://thespaces.com/studio-s... [thespaces.com]
https://www.marriott.com/hotel... [marriott.com]
https://www.hideawayreport.com... [hideawayreport.com]
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" For concrete houses to take off in most of the world, we're going to need a new generation of architects actually designing good looking houses with the stuff"
True, but in that case there is no problem because the people making the premeditated adult choice to build firetraps in wildfire zones get what they deliberately invited when fires burn them out.
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This is a bit silly about the Australian thing. Most Australians live in the urban areas, which most definitely were not at threat from the bushfires, no matter what the international media exaggerating the situation might imply. For example, in Melbourne, where about 4 million or 1 fifth of all Australians live, there was a small fire in an outer suburb that did minor damage to three houses, and that was the total extent of the bushfire threat.
Sure, maybe if you live in the forest you can build a concrete
Re: Then they can put it into old coal mines! (Score:2)
Beautiful solution (Score:1)
Concrete composition (Score:2)
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The rest of it is slaked lime. They called it portlandite in the article, but it's the same stuff.
https://en.wikipedia.org/wiki/... [wikipedia.org]
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The balance is the stuff that makes concrete very heavy and wish you hadn't decided to mix all of that concrete yourself.
The balance of the mass is various aggregate materials (sand, small rocks, etc.) and hydrated oxides of calcium, silicon, aluminum, iron, magnesium, etc. Specific compositions depend on the type of aggregate and cement.
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Magic and unicorns off course.
Oh, you mean in the real world, we have to burn a ton of energy to get the ingredients in and the final product out costing more energy than it's worth. As they said, this kind of carbon capture happens naturally, they just accelerate it with chemicals and larger concentrations of CO2, hence why they need a flue stack of a power plant.
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I smell a scam. Where is the portlandite from? (Score:5, Informative)
I read a very interesting paper by Professor Darryl Seimer from Idaho State University where he described a process of capturing CO2 in concrete. I learned quite a bit from this as well as other reading I did on how Portland cement does what it does. What this professor proposed was to mine naturally occurring lime in the form of basalt for use in cement. This captures the CO2 by turning the soft CaO into the very hard CaCO3, and it's this CaCO3 that is the primary constituent of Portland cement and limestone.
Where most cement get this CaO from now is limestone, which is heated in a kiln to release the CO2 from the CaO. Once they have the CaO then it is mixed with water to get Ca(OH)2, or slaked lime, or the portlandite mentioned in the article.
Think about that. This CO2Concrete is just ordinary Portland cement that they force CO2 into for rapid curing. A process that requires portlandite as a raw material. This curing is a process that would occur naturally once the cement is poured into a place where it is exposed to the air. A process that very likely got the portlandite by mining limestone which was put in a kiln to release gobs of CO2 into the air.
This is not a carbon capture process. At least no better of a process than any other concrete. It looks like they speed up the process, perhaps by a very significant margin. The CO2 captured is the same amount released in the limestone kiln they very likely used to produce the portlandite used to make the concrete.
That is unless then sourced the portlandite by a means other than a limestone kiln. Which if they did then this is just the same process described by Prof. Seimer many years ago but without the excessive effort of forced injection of CO2 to speed up the curing. This process of rapid curing would likely involve some very heavy equipment, that consumes a lot of power, because concrete is a very dense substance and we use a lot of it to make bridges, dams, runways, highways, high-rises, and far less massive items like birdbaths and garden gnomes.
In other words, I am not impressed. Not only am I not impressed but this looks like a scam to get government subsidies for a carbon capture process that doesn't actually capture any more carbon than if they just used whatever cement anyone else would use.
Re: garden gnomes (Score:1)
We had to destroy the village to save it (Score:2)
So you are saying TFA is "We had to release CO2 in order to sequester it" doubletalk?
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It speeds up the curing process, making the product stronger faster. If you can get credit for capturing your carbon now instead of everyone's carbon later, everyone else still has work to do to catch up to you.
It's definitely a wrong headline and shame on everyone involved in that.
Lime mortar is ancient technology (Score:2)
Lime mortar is used for brickwork. It is not actually concrete, but sets slowly by absorbing CO2 from the atmosphere, to become the CaC03 from whence it was created.
The process takes a few weeks, not that long.
The catch, of course, is that to make the molter you need to heat CaCO3 to produce CaO and release the CO2. So there is no net capture at all.
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And what that professor proposed is just the natural weathering process that is the most important non-biotic carbon sequestration process on the planet (and the biotic version of it is pretty important too).
Using natural lime in concrete, or at least sequestering the concentrated CO2 you get when producing it from limestone is a good idea. Co-locating pre-cast concrete factories with existing power plants and using them as CO2 scrubbers may also be a good idea.
so, where do they get the Ca(OH)2 (Score:5, Informative)
The portlandite, Ca(OH)2, is commercially produced from CaO---which is made by calcining CaCO3, which releases CO2. There is no net gain here.
Re:so, where do they get the Ca(OH)2 (Score:4, Interesting)
And there is the greenwashing scam. As pointed out above, the CO2 capture happens naturally and the transportation of both ingredients and final product would incur more CO2 burned than captured.
This is like those meat-free burger patties claiming they've got lower CO2 impact than meat patties but when you look at the details, it's because they outsource all the production of the ingredients and don't include the cost of eg. soy production.
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The portlandite, Ca(OH)2, is commercially produced from CaO---which is made by calcining CaCO3, which releases CO2. There is no net gain here.
Take a broader view. The win is carbon sequestration for profit. Conservatives who think AGW is a hoax will remain unmoved (can't fix stupidity, you can only work around it) but if this process turns out to be commercially viable (read: cheaper concrete) they will shrug and support it, which *is* a net gain for people who want to address AGW.
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As usual (Score:1)
All those magic "CO2 turn to something useful" usually lack the answer home much energy the process needs. You can turn CO2 back to oxygen and carbon and burn it again. Applause please.
What's the rush? (Score:2)
Maybe not.
This looks like a good way of pulling out CO2 for the long-term, but then I wonder why they think the old method is too slow. It's not like planting trees to address global warming
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If we get CO2 levels back to pre-1800 levels then plants will still be fine.
I was certain I recognized this (Score:2)
This is part of the reason cement is a contributor to CO2 release
Calcium Hydroxide is made from calcium oxide
Which is made by heating limestone or seashells (calcium carbonate) to just a bit above 1500F... Which releases the carbonate as CO2 that is locked to the calcium.
https://en.wikipedia.org/wiki/... [wikipedia.org]
Calcium oxide is usually made by the thermal decomposition of materials, such as limestone or seashells, that contain calcium carbonate (CaCO3; mineral calcite) in a lime kiln. This is accomplished by heatin
Environmental impact (Score:1)