Does carbon-eating cement (still) deserve the hype?

People here because of the NYT link might want to start with “An Introduction to Climate Progress.”   My bio is here.

I’m quoted in today’s NY Times article on Calera.  The “Silicon Valley start-up says it has found a way to capture the carbon dioxide emissions from coal and gas power plants and lock them into cement.”  I wrote about the company — and its critics — last April (see “Exclusive: Does carbon-eating cement deserve the hype?“).

The hype is still there, as this absurd quote from Silicon Valley billionaire Vinod Khosla makes clear:

“With this technology, coal can be cleaner than solar and wind, because they can only be carbon-neutral.”

Khosla keeps pushing these nonsensical statements that undermine his credibility (see “I would venture that the cleanest power will not be solar, it will be coal” and A pragmatic view of cellulosic biofuels or why VC Khosla is very wrong and VC Khosla blows his credibility dissing plug-ins.

At best, the Calera process couldn’t do more than capture and sequester the CO2 from a coal plant, so that wouldn’t be cleaner than solar and wind.  And you’d still have to capture 100% of the CO2 from the plant, which is unlikely, and sequester it for a long, long time since  “the burning of organic carbon warms the Earth about 100,000 times more from climate effects than it does through the release of chemical energy in combustion” (see “Why solar energy trumps coal power“).

And that assumes this process actually does what Calera says and is scalable, two propositions that remain in doubt, as the NYT notes:

Some climate scientists and cement experts are dubious that Calera can produce large quantities of cement that is durable and benign for the environment.

“People have been looking for ways to do this for 15 years,” said Ken Caldeira, an expert on the carbon cycle who is a senior scientist with the Carnegie Institution for Science at Stanford. “The idea that they’re going to come up with something that’s both economic and scalable? I’m highly skeptical.”

I am not going to repeat here my extended discussion of Calera from April 2009, which included climatologist Ken Caldeira’s chemistry analysis of the company’s process.  Caldeira made a strong case that

  • The scalability of the process is in doubt
  • We won’t know if net CO2 is saved unless Calera is much more forthcoming on all of the inputs and outputs

Caldeira emailed me several days ago that nothing he has seen has changed his basic view.

I ended that 2009 piece repeating Dr. Caldeira’s statement that Calera needs to provide the “inputs to and outputs from their process, in a way that allows balances of mass, energy, and electric charge to be assessed” independently.

The NYT notes today, “the company declines to share precise details of its process.”  Until those details are shared, no statements about “coal can be cleaner than solar and wind” should be given any credence, and all company claims about emissions benefits and scalability should be viewed skeptically.

The scalability issue is ultimately the most important because we need massive amounts of zero-carbon technology to avert catastrophic climate impacts (see How the world can stabilize at 350 to 450 ppm: The full global warming solution).  Even if the company could achieve some emissions benefits in niche applications, the hype could only be justified if it could achieve large emissions benefits in broad application.  That, too, remains in doubt, as the NYT notes:

Much of the skepticism about the project stems from the acid created in Calera’s chemical process. It has to find a way to dispose of it or neutralize it by adding alkaline materials, without creating more environmental problems or raising costs. Either would be difficult to do on a large scale, Mr. Caldeira said.

Mr. Khosla said that Calera has many sources of alkaline materials and many ways to dispose of acid.

If so, then Khosla and Calera should be happy to explain what these sources are and disposal methods are — and what the entire process is.

Climate scientists have raised other questions as well. “The chemical processes are known to exist, but if what you’re looking for is something that can be scaled up in order to actually mitigate CO2 emissions, it’s just a big problem,” said Ruben Juanes, assistant professor in energy studies at M.I.T.

Growing beyond the demonstration plant will be Calera’s next challenge, and it is a step that has stumped many clean technology start-ups.

“People have the impression that the energy sector is like the I.T. sector and you just have to build an iPhone and suddenly it will be everywhere, which is simply not the case,” said Joseph Romm, senior fellow at the Center for American Progress and editor of Climate Progress, an influential blog. “You have to build up so much infrastructure.”

People build cement factories for a long time, so building up an entirely new infrastructure simply can’t happen fast.

Since we need all the carbon-reducing strategies we can get, let’s hope Khosla and Calera have something that is effective and scalable.  But there is no reason to believe they have — until and unless they answer the questions posed by their critics in detail.

UPDATE:  Caldeira sends me this note today:

Instead of telling us what they plan to do, Calera is providing us with cartoons.

When people describe a chemical process and inputs and outputs, it is conventional to give formulas for chemical reactions and then describe from where you intend to source the reactants and what you intend to do with the reaction products.

Cartoons don’t really do the job.

There is one cartoon, labeled “our process”:

By my quick and possibly erroneous calculation, fly ash should be able to handle something on the order of 0.1% of US CO2 emissions. This might be good but does not seem scalable. I do not understand what Calera is planning to do with brines. I do not understand what “Electrochem” means.

There is another cartoon, labeled “inputs and outputs”:

Again, what is need is some chemical specificity. What is “manufactured alkalinity” — accelerated silicate rock weathering? What chemistry are they planning to apply to brines? What kind of waste water? etc.

In short, this is not enough specificity to judge definitively what they proposing to do.  Given the lack of information, I would have to put it as “I see no evidence that they have found an affordable and scalable process, but it is impossible to say anything definitive because they are not being adequately forthcoming.”

12 Responses to Does carbon-eating cement (still) deserve the hype?

  1. From Peru says:

    Check this OTHER carbon-negative cement producing method, called NOVACEM:

    “Novacem – carbon negative cement to transform the construction industry”

    I quote:

  2. mike roddy says:

    Khosla has been acting a little strangely since, after a series of big scores, he has been getting his butt kicked lately. He seems to think he can overcome it with promotion. Hint: Energy infrastructure is not like software, and is the opposite in many ways. Cost miscalculations bite you in the short and long term.

    I assume Khosla is talking about fly ash cement, and figuring out a way to include the CO2 in the mercury and NOx coal plant byproducts. There is already a problem with fly ash, actually: the mercury and other dangerous toxins in the fly ash do not remain captured, and leach even before the end of the concrete’s lifespan. If capturing the CO2 in the cement is done in via a separate process, the volume required for even a single coal plant is astronomical, and will not match up with local (concrete is always local) concrete demand.

    Remember, it takes 200 trainloads a day of coal to keep a power plant operating. That is a whole lot of CO2 to have to deal with regardless of the technology employed, and this is the specific reason why all forms of CCS have failed to pencil out. Even George Bush figured that one out.

  3. Bill R says:

    Determining the carbon-balance of a technology is certainly super-important in the age of the “climate crisis”, but coal has a footprint along the chain of it’s extraction, processing, and transportation that destroys water quality, denudes lanscapes of their soil, and blows the tops of mountains. Obviously, efficiency and conservation are our best energy investments — but I have a huge amount of scepticism about coal being more green than solar or wind… even considering their particualur issues.

  4. John Mashey says:

    Well, Vinod is just being … Vinod.
    And Ken’s concerns are well taken, although some of the secrecy may well be from the wish to get a business rolling.
    I still don’t understand the chemistry, and scaleability is a real issue.

    On the other hand, I have heard the company’s founder speak passionately for 15 minutes about the trouble ahead for the world’s corals, and then make some very persuasive observations about the utter necessity to do something about coal, i.e. He wished it would go away, but it wouldn’t. To me the real attraction if this is that if you could ever make it work,
    it sequesters carbon in something more permanent, produces a product that people buy (cement) whose manufacture normally creates a lot of CO2.

    The proof if the pudding won’t be in anything Vinod says, but in whether or not some real companies start doing this.

  5. catman306 says:

    Mike Roddy wrote: ‘Remember, it takes 200 trainloads a day of coal to keep a power plant operating.”

    Surely you meant 200 train CARloads (70-100 ton capacity each)? 20,000 tons/day

  6. Mike#22 says:

    I read the Calera material as saying:

    End products are precipitated calcium/magnesium carbonates and bicarbonates.

    Input materials are CO2 and a) calcium/magnesium chloride brines, b) possibly waste water with calcium or magnesium ions present (this seems like an energy expensive approach), c) seawater(?)

    CO2 capture to solution is made efficient by the alkalinty of the solution.

    Alkalinity is consumed by the precipitation of the carbonates and bicarbonates.

    Replacement alkalinity is supplied via a seperate electrochemical process which starts with sodium chloride and produces sodium hydroxide and hydrochloric acid.

    Sodium may be cycled through the electrochemical process and then through the precipitation process and recovered via reverse osmosis as sodium chloride, or sodium chloride may just be once through.

    For every molecule of precipitate produced, there appears to be either one or two molecules of hydrochloric acid produced. At any kind of scale, that is one heck of a lot of HCl. What are they going to do with that, I wonder?

  7. Kiwiiano says:

    Some years ago I saw mention of a concrete expert’s visit to the Egyptian pyramids, where he claimed that contrary to the tradition that the huge stone blocks were carried many miles from quarries to the construction sites (perhaps with the aid of flying saucers) the blocks were actually a form of concrete, poured in situ. He could see the expected voids within the ‘stone’. To reinforce his claim, he found resources suitable for the manufacture of this concrete in the region.
    If this is true, we should be looking at this alternative to Portland cement given its carbon footprint. Whatever variation of concrete the Egyptians were making, you can’t argue with its longevity, at least in a dry climate. The modern stuff appears to have a use-by date measured in decades rather than millennia.

  8. From Peru says:

    I still think that an excellent “carbon wedge” would be swithching from carbon-positive Portland Cement (that contributes roughly 5% of global emissions) to carbon-negative ones (like the NOVACEM cement that I linked above).

    That will transform the + 5% into a – 5% , actually equivalent to a 10% reduction in emissions.

    This post on CP only tells us that the CALERA cement isn’t a viable option. But there are still other options, like the NOVACEM one, that will probably work.

  9. john atcheson says:

    Coal cleaner than solar? I assume then the system is also capturing mercury, cadmium, SOx Nox,and particulates — I also assume that somehow mountain top mining — or any mining — also magically stops — as well as the ancillary pollutants associated with moving the coal …

    This is obviously a pump and dump scheme — talk up the technology, get investors in (after going public) talk up the stock, then sell and leave folks holding a worthless scrap of paper.

    Surely Calera doesn’t actually believe this hyperbolic BS.

  10. mike roddy says:

    Catman, yeah, I meant 200 freight train carloads. That is a lot of coal.

  11. Manu Sharma says:

    Geopolymeric concrete already exists as an effective substitute for concrete based on Portland cement. It is said to reduce emissions by 80%. Unfortunately few people know about Geopolymeric concrete. An Australian scientist I’ve interacted with on this issues believes it’s definitely scalable.

  12. David Doty says:

    When Calera first opened their website, it included a number of junk-science presentations with lots of graphs and unintelligible techno-speak that purportedly showed how they would make a hydraulic cement that would have a negative CO2 footprint. As various real scientists began posting critiques over the past year, Calera has steadily pulled this material (which any real chemist could easily show to be junk) from their website; and their publicly released material has steadily become more vague – lacking even the pretense of being scientific. However, he can’t pull his published pending patents from the public record, where one can gain some insights into his confused thinking.

    In his pending patents, Constantz reports an example in which he adds at least as much Ca and Mg (as powdered dolime, a mixture of MgO and CaO) to the seawater as is precipitated from it in other forms. Constantz says if the pH is raised above 10.3 (by adding a strong hydroxide), some of the CO2 will stay trapped in the precipitated CaCO3 crystals. Perhaps so, but how much and for how long? According to the reported analysis, the precipitate was 11% C. CaCO3 is 12% C, and CO2 is 27% C, so it looks like there wasn’t any extra carbon trapped in the precipitate. There is confusion in some of the other data, where in one table it appears that the precipitate is 46% CaO (only a fraction of the dolime that was added was allowed to react), but in another table it seems that the precipitate is essentially all CaCO3 except for a little MgCO3 and other minor components.

    And where did the initial CaO and MgO come from in Constantz’s experiments? From firing (calcining) carbonate rocks (such as limestone), requiring 4 MJ/ton, and emitting more CO2 than the CaO and MgO would later absorb when returning to the carbonates. Is there any other good source of dolime? No. If there were, prehistoric man would surely have figured out how to make concrete structures at least 10,000 years before the Egyptians did. And what’s the point of producing a concrete extender by an incredibly expensive and carbon-intensive process when there is no shortage of sand, rocks, fly ash, and other suitable extenders? Various statements in these patents lead one to suspect Constantz originally expected to somehow precipitate CaO and MgO from seawater by adding CO2. When he realized this was impossible, he decided to concoct an elaborate and incredibly expensive method for synthesizing minerals that are cheap and abundant.

    Why does Constantz continue to refuse to say anything substantive when he has pending published patents? Where are the peer-reviewed papers?
    The chemical equations and logical explanations of mass balance and energy balance? What has happened to scientific review?

    Does Constantz have substantial expertise in cements? Indeed. He just also happens to be a deluded scam artist. Unfortunately, there are thousands of similar scam artists operating today in the field of renewables, and that is making it very difficult for those of us with real, paradigm-changing advances (see the WindFuels website) to be taken seriously.