Please create an account to participate in the Slashdot moderation system

 


Forgot your password?
Close
typodupeerror
×
Earth Science

Green Cement Absorbs Carbon 213

Posted by kdawson from the do-not-like-green-cement-and-ham dept.
Peace Corps Online writes "Concrete accounts for more than 5 percent of human-caused carbon dioxide emissions annually, mostly because cement, the active ingredient in concrete, is made by baking limestone and clay powders under intense heat that is generally produced by the burning of fossil fuels. Now Scientific American reports that British start-up company Novacem has developed a 'carbon-negative' cement that absorbs more carbon dioxide than it emits over its life cycle. The trick is to make cement from magnesium silicates rather than calcium carbonate, or limestone, since this material does not emit CO2 in manufacture and absorbs the greenhouse gas as it ages. 'The building and construction industry knows it has got to do radical things to reduce its carbon footprint and cement companies understand there is not a lot they can do without a technology breakthrough,' says Novacem Chairman Stuart Evans. Novacem estimates that for every ton of Portland cement replaced by its product, around three-quarters of a ton of CO2 is saved, turning the cement industry from a big emitter to a big absorber of carbon. Major cement makers have been working hard to reduce CO2 emissions by investing in modern kilns and using as little carbon-heavy fuel as possible, but reductions to date have been limited. Novacem has raised $1.7M to start a pilot plant that should be up and running in northern England in 2011."
This discussion has been archived. No new comments can be posted.

Green Cement Absorbs Carbon More

Green Cement Absorbs Carbon

Comments Filter:

  • Strength? (Score:4, Insightful)

    by plnb ( 579253 ) on Tuesday August 11, 2009 @09:16PM (#29032787)
    No mention in the article of the strength of the new material. How would this compare to regular concrete?

    • Re:Strength? (Score:4, Insightful)

      by mysidia ( 191772 ) on Tuesday August 11, 2009 @09:26PM (#29032847)

      Strength is important, and so is longevity.

      I don't want to be in the car on that 50 year old bridge that collapses, because they didn't do right trials to detect aging and absorbing CO2 having an adverse effect on the material's strength over time.

      Concrete is a rather proven material that has been proven over hundreds of years; spontaneously replacing it now could be highly dangerous.

      Much like replacing the OS on a computer system that's been chugging a way for 500 years, with a brand new release version.

      Sure, there may be an efficiency improvement. There can also be unexpected bugs.

      • Re: (Score:2, Interesting)

        by Anonymous Coward

        Sure, hundreds of years, if not more. Do you mean that this is the first time someone has changed the recipe?

        • Re: (Score:2, Informative)

          by Sensiblemonkey ( 1539543 )
          A *lot* more than hundreds of years. The Romans used concrete all over the place. Even the Pantheon's dome is concrete.

          • Re: (Score:2, Insightful)

            by jelle ( 14827 )

            Do you seriously believe that modern concrete is the same recipe, strength, and longevity as roman concrete?

      • Re:Strength? (Score:5, Insightful)

        by GeigerBC ( 1056332 ) on Tuesday August 11, 2009 @10:02PM (#29033057) Homepage
        You're right in that we want strong and durable concrete. As another poster pointed out we are constantly changing the concrete mix proportions and admixtures. Admixes themselves are relatively new (~50 years) in the grand scheme of making concrete. It gets introduced slowly...and the universities then test it beyond belief for different properties. Maybe you'd like to be a grad student in civil engineering and make hundreds, or perhaps thousands of ever so slightly different mixes to determine the properties of your variable. I'm all for making concrete more "green" and I figure the universities and companies will test it before they use it in important projects.

        • Re: (Score:2)

          by bitrex ( 859228 )
          For a moment I thought you were going to say "Maybe you'd like to be a grad student in civil engineering and make hundreds, or perhaps even thousands of dollars!"

      • Re: (Score:2)

        by Xtravar ( 725372 )

        All of the roads and bridges aren't going to be replaced at once, and especially not any bridges that rely on concrete for structural integrity.

        Not to mention, every time a material like this comes out, it's prohibitively expensive, so probably only eccentric European cities will even try it.

        I wouldn't worry too much about it... nobody's going to take away your concrete just yet.

      • Much like replacing the OS on a computer system that's been chugging a way for 500 years, with a brand new release version.

        Sure, there may be an efficiency improvement. There can also be unexpected bugs.

        And we could even use a car analogy.

        It would be like replacing the fuel on a car that's been chugging a way for 500 years, with a brand new fuel type.

        Or even for a mix of fuel types.

        We could call that mix "mutant", or "hybrid", or something like that.

      • that has been proven over hundreds of years;

        I believe thousands is the correct order of magnitude. The Colosseum and the Aqueducts have some of that proof.

    • No mention in the article of the strength of the new material. How would this compare to regular concrete?

      Who cares dude? It's effin' green! just like the cash we can get from investors because it's like fashionable to investing in things that are green!

      • Do you have any basis for thinking this is weaker, or is this just your knee-jerk response to anything that could help prevent global warming? Let me guess, you don't believe in it.

        • Maybe you should consider your own biases and learn some reading comprehension before writing knee jerk responses (which mine wasn't). I very carefully and specifically didn't mention or discuss the relative strengths, so anything of the sort you saw is a product of your own bias and ignorance.
           
          My comment was (to those with the ability to read) plainly sarcasm and commentary on the current fad of 'being green'.

        • Everyone has lost their mind on this whole green anti-carbon thing. I am just shocked how quickly it rose to the incredible levels of hype it has.
          Even back in the day when the concern for CFCs was high enough to ban it for nearly all purposes did not seem to have this level of hype around it. And cleaning our coal plants and car exhaust to reduce acid rain was great, but we never had Hollywood celebrities going around showing off their new cars with platinum and rhodium catalytic converters.
          The media has ma

    • It doesn't matter how long it has to last, because here in Quebec Canada, the mafia...pardon me...the politicians, have it that they redo the cheapest contracts possible, instead of quality, so we have bridges falling, and roads with pot holes the size of a car....but, they redo the concrete every year, so we will be repaving yearly anyways, so it doesn't have to last long, when the gov. does not seem to care about the length of time it has to last.

  • Less CO2 = $Green$ (Score:3, Insightful)

    by Scubaraf ( 1146565 ) on Tuesday August 11, 2009 @09:24PM (#29032835)
    I see one of the early tags is 'negligible.'

    Maybe it is in terms of global CO2 levels, but under a cap and trade system, this will turn an industry that might have to buy CO2-emission rights into one that could make money selling them!

    • Re:Less CO2 = $Green$ (Score:5, Insightful)

      by Mad Merlin ( 837387 ) on Tuesday August 11, 2009 @09:53PM (#29032999) Homepage

      Even if it is negligible, "going green" is the trendy thing to do nowadays, so as long as it seems like they're making an effort, that's far more important than if it actually helps.

    • Re:Less CO2 = $Green$ (Score:4, Insightful)

      by Dragonslicer ( 991472 ) on Tuesday August 11, 2009 @10:17PM (#29033135)
      A solution that fixes only 1% of a problem may be considered negligible, but gather together a hundred such "negligible" solutions and see what you get.

    • Re: (Score:2, Offtopic)

      by account_deleted ( 4530225 )
      Comment removed based on user account deletion

      • Re:Less CO2 = $Green$ (Score:4, Interesting)

        by bitrex ( 859228 ) on Wednesday August 12, 2009 @02:09AM (#29034403)
        It's not just you, I've heard it said that the next bubble of the 21st century, after the tech bubble and the housing bubble, will be the carbon credit bubble. There is a new government-created "commodity" in carbon credits, which are government-mandated to decrease in number over time, and are therefore government-mandated to increase in value over time. Sounds like something that's right up Goldman Sachs' alley. I might even guess that the collapse of such a bubble would occur when rampant speculation on carbon credits drives the prices of said credits up high enough that corporations who are able to do so start shifting their industry to nations where the carbon credit regulations are unenforced or unenforceable, nations which would gain enormous financial benefit by being "carbon credit havens." The value of carbon credits could only be propped up for as long as investors felt secure that everyone was playing by the same rules, and we know how often that happens.

      • Re: (Score:2)

        by Toonol ( 1057698 )
        Dispensations. Yes, I get the same feeling. It's a way for rich people to purchase forgiveness for sins.
  • the composition of asbestos?

    • Re:Isn't magnesium silicate... (Score:5, Informative)

      by reverseengineer ( 580922 ) on Tuesday August 11, 2009 @09:54PM (#29033013)
      It's the composition of quite a few minerals, including asbestos, but also talc and soapstone. The issue with asbestos isn't the chemical composition per se, but rather its inclination to break into micron-sized fibers that can be deposited in the lungs. Compare fine silica, which is nearly chemically inert, but poses a serious danger if inhaled.

      • The company's site is very light on detail, but I did find this in one of their (two) press releases:
        Novacem's revolutionary technology is based on magnesium silicates rather than limestone
        (calcium carbonate) as is used in traditional Portland cement. Global reserves of magnesium
        silicates are estimated to be in excess of 10,000 billion tonnes. The company's technology
        converts magnesium silicates into magnesium oxide using a low carbon, low temperature process,
        and then adds special mineral additives to produ

    • Well H2O is the major component of cancer cells. Though, I am not sure where this is going.

  • Severe doubts (Score:5, Interesting)

    by sofar ( 317980 ) on Tuesday August 11, 2009 @09:28PM (#29032859) Homepage

    This sounds like a concrete nightmare:

    If a material absorbs so much CO2 over it's lifespan, it significantly alters the chemical composition and therefore strength.

    I doubt any builder will use this material unless it's been proven that the new material is sufficiently stable.

    Example: as a geology student, I ran into an area in central spain with lots of Gypsum sediments (Ca|MG.SO4). Putting limestone and concrete buildings on this sediment wasn't done until the 20th century, but all the buildings built in that area are long gone, even though in nearby towns they still stand tall. Reason? The Gypsym in the soil chemically eats the mortar and limestone (CaCO3) out of the structure on top of it, making it crumble within a few decades. The Gypsum areas are largely a wasteland where only very few buildings remain.

    Now, Mg.Ca-CO3 (dolomite limestone) is largely as stable or more stable than pure limestone, and certainly harder, but any new formula for the glue in concrete will have to pass the test of time before it will be widely adopted, especially in e.g. bridges and skyscrapers...

    Perhaps we can start with the interstates, nobody would notice if they started to crumble early ;)

    • Now, Mg.Ca-CO3 (dolomite limestone) is largely as stable or more stable than pure limestone, and certainly harder...

      That's dolomite, baby.

    • Re:Severe doubts (Score:4, Interesting)

      by Anonymous Coward on Tuesday August 11, 2009 @10:21PM (#29033163)

      Interstates, roads, curbs, sidewalks, etc...
      Structure and load bearing however, strength is where it is at. Also most concrete is however very brittle. It is good at load distribution not in actual strength.

      Also many times these structures are torn up and tossed into large piles. They could continue to soak up carbon.

      The idea is sound, but in practice probably wouldnt be so good as you pointed out. In some applications it is a decent idea.

      • Re: (Score:2, Informative)

        by ATestR ( 1060586 )

        It is good at load distribution not in actual strength.

        More precisely, concrete is good in compression, but poor in tension. That's why you fill it with steel bars if it has to take any bending forces that would put part of it in tension.

    • I would think that sidewalks and minor side roads would be the place to start. If EU is going to start this, then perhaps we should order some of this and put it into various places (none structural) to see how it lasts. In fact, just thinking about it, it MIGHT actually improve the roads. It would slowly gain weight which MIGHT also strengthen bonds in it, though I notice that they have said NOTHING about that. I would think that if it did get stronger, then they would say something. Regardless, if this is

    • Bath Stone already does this (Score:5, Interesting)

      by Kupfernigk ( 1190345 ) on Wednesday August 12, 2009 @02:24AM (#29034465)
      I live in the Bath area of the UK. The main building material is Bath stone, considered very desirable because as dug out of the ground it is reasonably soft and easy to form, but over its life it absorbs carbon dioxide and becomes harder.

      The house I live in is a mere 150 years old, but most of the street it is in was built between 1690 and 1695. In fact, our foundations go back to then. The composition and structure of Bath stone has been extensively studied, and I would imagine the results are just a small part of the data the technologists will take into account.

      And your point was, again?

      • Re: (Score:2)

        by sofar ( 317980 )

        Those are non-reinforced structures, IOW Gravity is the main force on the rock. Extension forces are much harder for rocks, and require reinforcement. As one of the posters below points out, having strength alter (in any way) can severely increase the risk of failure for reinforced structures.

        Just because Bath didn't fall over, doesn't mean it isn't safe for everyone.

    • Re: (Score:2)

      by Toonol ( 1057698 )
      My suggestion would be to build stuff out of wood. Lots of it. Every log is 30-40% carbon, and pulls the CO2 out of the ecosystem for potentially centuries.

    • Re: (Score:2)

      by julesh ( 229690 )

      If a material absorbs so much CO2 over it's lifespan, it significantly alters the chemical composition and therefore strength.

      Yep. Of course, all cement absorbs CO2 -- during its lifespan it gradually changes back from calcium hydroxid back to calcium carbonate. The process is one of the most common failure modes of reinforced concrete structures (although on non-reinforced structures it isn't usually a problem).

  • Seriously... (Score:4, Insightful)

    by redmond ( 611823 ) <marshal...graham@@@gmail...com> on Tuesday August 11, 2009 @09:28PM (#29032861)
    "The building and construction industry knows it has got to do radical things to reduce its carbon footprint and cement companies"

    Seriously? At least here in the Midwest (USA), construction bids still go to the lowest bidder and there are huge piles of construction waste that go straight to the landfill. They won't change until someone makes them change.

    • They will be forced to change by tax and trade. If carbon emissions are taxed then the lowest bidder will likely be the one with the smallest CO2 output.

  • I have a similiar green question about concrete (Score:3, Interesting)

    by Anonymous Coward on Tuesday August 11, 2009 @09:40PM (#29032925)

    Fly ash, which is the ash waste from burning coal is also being used in concrete to lessen the amount of C02 concrete creates as well as improve strength. My question is since this fly ash has a high amount of toxins(heavy metals) in it, would the toxins be locked in the concrete or would they seep out if exposed to water or other stresses over time.
          I am curious to know this because apparently fly ash can make concrete easier to work with in insulated concrete form construction and because other types of materials that compete with concrete seem to be using it. Gigacrete.com ( supposedly 10,000 psi strength) though not for structural use is an example. I can't tell if they are using weasel words though because they claim there binder is nontoxic, I can't tell if they are purposely talking about the binder being non toxic and not the fly ash.
        I hope someday to build a house out of ICF's (insulated concrete forms), I guess I must have taken to heart that story of the three little pigs when I was young.

    • Re:I have a similiar green question about concrete (Score:4, Informative)

      by SomeKDEUser ( 1243392 ) on Wednesday August 12, 2009 @12:40AM (#29033965)

      Fly ash is actually widely used as a supplementary cementitious material. It has all sorts of excellent properties, it reduces porosity, increases durability mitigates ASR. It is a so-called pouzzolane, which means it reacts with the carbon hydroxide produced by the reaction of the cement and transforms it into calcium-silicate hydrate which is the main responsible for the strength of cement (C-S-H is the main product of the reaction of cement with water)

      In fact, we are running out of sources of fly ash to put in cement. So basically, no, there is no risk, or we would have known by now. Also, you have to realise that FA is essentially pure amorphous silica, and that heavy elements would only be there as traces and stay trapped as the FA reacts.

    • Most modern UK houses have fly ash block as the inner wall of the double walled skin. It has been around for many years and its properties are well understood. Interestingly, its use was originally seen as a green win/win situation because it required less energy to produce than brick, and largely solved the problem of disposal of power station ash.

      I've occasionally wondered if the real technological fix for nuclear waste would not be to wait till the short lived isotopes have fissioned (in dry cask storage

  • Inaccurate (Score:3, Informative)

    by Brian Gordon ( 987471 ) on Tuesday August 11, 2009 @09:41PM (#29032931)

    Novacem estimates that for every ton of Portland cement replaced by its product, around three-quarters of a ton of CO2 is saved, turning the cement industry from a big emitter to a big absorber of carbon

    You mean turning the cement industry from a big emitter to a small emitter...

    • Nobody said that a ton of concrete produces a ton of CO2.

  • That's a big goal ... (Score:5, Informative)

    by MartinSchou ( 1360093 ) on Tuesday August 11, 2009 @10:12PM (#29033089)

    One of my dorm friends, Jakob Husum [www.dtu.dk], wrote his dissertation [nt.ntnu.no] on ways of optimizing cement productions.

    One of the rather impressive/scary things about that, is that it is responsible for about 2% of the world's energy consumption. That's an insane amount of energy for something that isn't even an end product.

    The first paragraph of the paper actually grabs you by the balls and twists firmly:

    Production of cement is one of the most energy
    intensive industrial processes, consuming up to 2 % of the worlds electricity due to several low eciency processes. The grinding of cement clinker from the kiln is the most inefficient process in the manufacturing, with an efficiency of 1 % (Benzer et al., 2001).

    Can't quite remember how much of the energy if spent on the last bit, but I think it was something like 25%. That's 0.5% of the world's energy usage spent on a 1% efficient process. Now imagine you could up the efficiency to 10% or even 5%. That'd be a reduction of the world's energy usage of 0.45 or 0.4% respectively, simply by improving a single process.

    Now, there are a lot of arguments for saving energy. Saving the environment, less pollution etc., but it's hard to overlook the economic incentive of cutting back energy costs of a production, where a large part of the process is 1% efficient.

    • what are the other costs for this new material? It is possible that this will take a lot more energy.

      One odd idea for cement is to start using solar to make it. I would think it should be possible for using a solar kiln to do the heating of this. Yes, it will not solve the breaking up, but, the true energy intense part is the heating.

    • Re: (Score:2)

      by khallow ( 566160 )
      I think there are two missing ideas here. First, that the expenditure of energy yields a considerable return on investment. Second and not coincidentally, energy input is probably not the most significant cost input to the system (you have to consider also labor and capital depreciation and maintenance). Finally, it's worth noting that this sort of energy inefficiency isn't remarkable. For example, roughly a third of the global energy budget is consumed through the internal combustion engine which is someth

      • For example, roughly a third of the global energy budget is consumed through the internal combustion engine which is something like 20% efficient at best.

        True, but it would be more correct to say that it is spent on transportation. And even then, the ICE is 20 times as efficient as that process in cement production.

        I don't know about you, but personally I wouldn't choose something that is 20 times more effective as an example of how something else isn't remarkably efficient. Imagine how horribly bulky cars

  • Green is the new Black (Score:4, Insightful)

    by tengeta ( 1594989 ) on Tuesday August 11, 2009 @10:21PM (#29033165)
    and by that phrase, I mean its popular bullshit. Most of the "green" things that have been devised over the past few years do NOTHING other than hold the carbon and make it the next generations problem instead. I thought the entire idea here was to NOT do that, but then again we live in an excessively hypocritical society that makes things up so they can make money, and this may just have been the latest and greatest. I'm not saying environmentalism is bad, but the majority of it so far isn't actually doing any good for the environment, its just helping the stock holders behind the products involved.

    • Re: (Score:3, Insightful)

      by Raptoer ( 984438 )

      I agree with you on the 'majority of it isn't actually doing any good' but I disagree on the hold carbon part. It's not like toxic waste where it's still a problem if something absorbs it. Carbon in the concrete isn't carbon in the air, and only carbon (dioxide) in the air is considered harmful to the environment. If it is in solid form (as calcium carbonate, or some other chemical, not as solid carbon dioxide) then it does nothing to the environment except sit, which it was doing before in the form of hydr

  • Not exactly a first (Score:3, Informative)

    by fru1tcake ( 1152595 ) on Tuesday August 11, 2009 @10:44PM (#29033295)
    A similar product [abc.net.au] was presented on Australian TV [abc.net.au]) in 2005.

  • Most of the CO2 comes from calcination (Score:5, Interesting)

    by wiredlogic ( 135348 ) on Tuesday August 11, 2009 @11:41PM (#29033595)

    The summary doesn't explain things very well. Just to set things straight, most of the CO2 emissions from portland cement production is not from the fuel burned in the kilns but from the gas released by the limestone itself during the calcination process. The only real incentive for the use of energy efficient kilns is to reduce fuel costs and not to reduce emissions. The upside is that cement will reabsorb much of the released CO2 as it cures over the course of time.

  • Could cement plant be colocated with power plant? (Score:3, Interesting)

    by JSBiff ( 87824 ) on Wednesday August 12, 2009 @12:10AM (#29033765) Journal

    "...mostly because cement, the active ingredient in concrete, is made by baking limestone and clay powders under intense heat that is generally produced by the burning of fossil fuels."

    This sentence got me to wondering. . . one of the big problems of thermal electric power plants (coal, natural gas, nuclear), is that we throw away 50-60% of the heat as waste heat into the environment (nearby body of water or the air). Could the waste heat from a coal or nuclear power plant be used to 'bake' the cement? In the case of coal, sure, you're still burning fossil fuels, but those were being burned *anyhow* to generate electricity, so why not put the waste heat to use? You are, *at least*, not burning any *additional* fossil fuels just for the cement, right? In the case of Nuclear, you are using a very low-carbon heat source, and again, doing something useful with the waste heat?

    • Re:Could cement plant be colocated with power plan (Score:4, Informative)

      by HornWumpus ( 783565 ) on Wednesday August 12, 2009 @12:46AM (#29034011)

      It's not impossible but remember that (IIRC) theoretical optimum thermal efficiency is (THigh-Tlow)/THigh.

      In practice that means that waste heat is generally too cold for this process. If it were hot enough to make cement it would be hot enough to extract power from.

      Waste heat from Combustion Turbines (CTs) is already being used to generate steam in cogen plants.

      'Pure' CTs are typically super-peaker plants. Lousy efficiency but they start and ramp fast. Which in practice means their heat is too unpredictable to run that kind of process in any case.

      Typical applications of CoLo heating are greenhouses, malls and other large buildings. Market forces are making this (space heating) happen quite nicely where ever economically practical.

      My university was/is entirely heated by the waste heat of the coal fired plant on campus (50+ year old setup). Good fun in the steam tunnels. Access to boiler rooms.

    • Re: (Score:3, Informative)

      by vlm ( 69642 )

      Could the waste heat from a coal or nuclear power plant be used to 'bake' the cement?

      Far, far too cold.

      Typical Rankine cycle plant tops out around 500-600C at the hot end. Higher would be nicer, but the problem is you need a material with immense tensile strength to contain the pressure, pleasant failure modes (not brittle), and good heat conductivity. Sorry but 600C is about as good as our technology gets. The cold end is of course much colder.

      http://en.wikipedia.org/wiki/Rankine_cycle [wikipedia.org]

      On the other hand, cement kilns really need about 1500C. Kilns don't operate at much pressure, and ins

  • CO2 Absorbsion (Score:5, Insightful)

    by matria ( 157464 ) on Wednesday August 12, 2009 @12:56AM (#29034075)

    Why not just plant more trees around buildings made of concrete? That seems to me to be a more useful, long-term "incentive" program than some we've seen lately.

  • Green cement is people! Green cement is people!

  • There's more than a small gremlin in this plan-- transport.

    Cement and concrete are always made close to their destination, because, the stuff is, like, really, really heavy.

    Now one suspects that the required chemicals for this new CO2 absorbing stuff are not equitably distributed.

    So the places without the stuff would need to have the stuff trucked, barged, or railed in. That would send the
    price of this concrete through the roof. Not to mention releasing more CO2 from all the diesel engines pushing the stu

  • The goal to reduce carbon emissions is obvious, and this sounds like a good start (especially as one commenter noted -- on small scales to start, residential sidewalks, etc) but has anyone thought about the potential for impact of removing such a large portion of C02 from the environment on our fauna that requires CO2 for survival? I know we're putting off more than nature would due to processes like the creation of concrete, but could that mean that the plants of today are now depending on it? One argument

    • Production of concrete is vastly outweighed by coal plants and gasoline use. And the high CO2 levels have only been around for 50-100 years, which is far too brief for any significant evolution.

Slashdot Top Deals

If all else fails, lower your standards.

Close