Mashey on a promising new technology for carbon sequestration

Hi!

Iâm e geochemistry PhD student and I have tried to look in to this a little bit for a Swedish company. One way that is discussed is adding some sort of mineral, e.g. Olivine http://scienceblogs.com/stoat/2008/12/hot_air.php#comment-1246183 however there would be a risk for acidification, what do you think would be the best way to sort the acidification problem?

And maybe the more crucial part, what concentrations is needed to get high enough reaction rates? Temperature?

Magnus:

Short answer: I don't know, and it didn't come up, and there is . I've heard of this general idea before, but there are always lots of ideas floating around in R1/R2/D1 state (as per Dot Earth post. This looked further along than I'd thought (D2 and maybe further), and there's nothing like seeing an expert talk to a serious audience to get one convinced that something is at least looking at, hopefully by people who know much more than I do.

Here are a few more references:
Scientific American and Concrete Producer Online.

At USPTO, I did a quick search for Constantz, (discovering he lives in the same town as I do), and one of the early hits was 20090001020. It sounds like it's mostly for desalination, but also says:

"Aspects of the invention include carbon dioxide sequestration. Embodiments of the invention further employ a precipitate product of the carbonate compound precipitation conditions as a building material, e.g., a cement. Also provided are systems configured for use in methods of the invention."

My brain is too tired right now to plunge into a patent writeup in a new turf. [I know how much it hurts to read patents in areas where I know something, so I won't start this late in the day.] But, maybe somebody who knows more can look at this.

Can I just check my understanding: the calcium/magnesium comes from hard (possibly sea) water? In effect, the overall reaction is something like CaSO4 + Co2 + H2O -> CaCo3 + H2SO4 ? If so, it reverses the sort of thing we did in first year chemistry at school.

I don't know about 'gotchas' but I'd have supposed the big innovation here is being able to use carbonates as construction materials - as I understand it at present cement is made from carbonates with release of CO2 into the atmosphere.

The World of Concrete link is broken and I can't see an obvious fix.

Sea water have high concentrations of "dissolved" Mg (and Ca) add to water (H2O) CO2 <----> H2CO3 <-----> CO3 ... Ca+CO3 <----->CaCO3 ... Simplified...

Sequestering CO2 in the cement process is not new: attempts to do it with plain old Portland cement are at least a decade, or two, old.

And carbonate cements are not particularly new. Nature's been doing them for aeons. So have we (but not for aeons): the Romans used carbonate mortars. I remember encountering carbonate cements in my studies a good few years earlier than the 1995 abstract above, but it's all horribly vague now. And I can't recall why or if the aforementioned CO2 capture route ever took off industrially (somebody'll know), because I didn't go down the cement materials science route subsequently.

So, it'll be really interesting to see what is novel about this new process and what the mechanical and physico-chemical properties of the ensuing cement/concrete are like.

I guess the time is about right to look at them anew; or if not anew, then with renewed vigour.

I tried to fix the World of Concrete link. It works for me now, but the original link only works after you've done a search.

Doh! "why or if" should have read "whether" ... and I still don't know.

FWIW California burns lots of coal, in New Mexico

Thanks, Tim.

One thing that crossed my mind reading the WoC article is that if this is done on the scale required to substantially reduce our atmospheric CO2 levels, would it deplete the ocean of calcium, thus affecting shellfish as well its ability to absorb CO2?

(I'm still getting this mental image of buildings melting away in acid rain, though... denialists look away. Plus "Do not use to clean the walls of your house" admonitions on toilet cleaner.)

I also was wondering what happens to ecosystems, especially those in "briny hard water found in sedimentary basins", as well as to global ocean chemistry if this process really takes off. I'm still surprised that this isn't one of the first things considered / presented about any of these topics. We no longer have the excuse of thinking that hey, nothing we do can affect the Earth as a whole after all. And there's a serious risk that as all sorts of ecological capacity gets squeezed at once, these kind of efforts just move damage around.

I also wonder how long the sequestration lasts.

Not a lot of detail about the capture part of the CCS.

Since coal boiler flue gas is about 80 percent NOx and contains particulate, HG and SO2 emissions, how will the carbon dioxide reaction with sea water fare if it contains NOx, SO2 contaminants? Or, are we looking a very expensive oxy-fired coal furnace (great idea and expensive)?

John Mashey, can you give a few words to the CO2 capture part of the equation?

John McCormick

California (as Eli mentioned) does use some coal power, although perhaps it is all imported. PG&E claims that for the current calender year 4% of its generation will be from biomass (versus 2% from coal), perhaps this would be a usable source (not quite as high in CO2, as biomass contains more hydrogen than coal).

In the best case, where this is no more expensive than traditional concrete and the properties of the concrete are good scaling is still limited to the size of the concrete market. It will never be a complete answer to CO2 emissions, but it could be a nice wedge.

Hello Mr. (Dr.?) Mashey,

Would this process perhaps tie in with this company's efforts?

http://www.grestech.com/

John, coal boiler flue gas is almost all CO2 and N2. 80% N2 makes sense with the balance CO2 and traces of NO2 and SO2. otherwise there would be big trouble.

There are other cement technologies coming along: according to the Guardian, Novacem in the UK is working on a magnesium silicate cememt which is carbon negative.

Every little bit helps...

Rich - The "briny hard water found in sedimentary basins" would be water in sedimentary rock, probably pretty deep - comparable to the depths from which oil is extracted. So they aren't talking about damaging ecosystems such as the Great Salt Lake.

In some places (such as around Albuquerque, New Mexico) briny groundwater is already being considered as a possible source of future drinking (etc) water... if some energy-efficient way is found to desalinate it.

John,
An interesting article, even if devoid of some crucial chemical detail. However, it seems to me that any form of CCS is the last of the sins of AGW âdenialâ â a form of the âtechnology will save usâ argument. (and I stress Iâm not accusing you of supporting this).

I take James Hansenâs view that using coal to generate electricity should be phased out extraordinarily quickly â but for additional reasons to his.

I have been a committed AGWarmer for a decade and a half but more recently I am becoming much more of a âneo- Malthusianâ.

Coal, and derivatives like coke, are still the major energy means of Iron smelting. Wasting coal by just burning it to generate electricity means that mankindâs ability to manufacture Iron & Steel, and probably many other vital metals, is literally disappearing very quickly.

I was reminded of this recently by the article in SolveClimate about the book, âLimits to Growthâ, by Dennis Meadows, originally published in 1972 and a â30 year updateâ in 2004. Amongst many other finite resources, the concept of âLimits to Growthâ gives the alarming prospect that usable coal reserves will be completely gone by mid â to end this century, (according to how you define usable reserves).
http://solveclimate.com/blog/20090209/limits-growth-author-honored-once…

I wonât bore you with all the details - (being completely honest, Iâve forgotten a lot of them from the original book and Iâm waiting to receive the update version), - and, yes, it is of highest priority to reduce GHGs, especially CO2. But, coal, (& oil & lots of other materials) will certainly run out due to the pace of industrialisation and other variables.

In my opinion, you can âfiddleâ with the figures of the equations they use to your heartâs content but no matter how you change the five categories of figures (see wiki for a quick summary, http://en.wikipedia.org/wiki/Limits_to_growth ), itâs hard to deny the high probability of collapse of civilisation âas we know itâ within, what? 100-200 years.

Okay, you may say ânewâ technology almost certainly will emerge but the real question we should be asking is will it âreallyâ sustain anywhere near our current lifestyles.

Sorry to be so pessimistic - but any comments?

I didn't look at the links, but I suspect that even if this technology proves out completely it won't be a panacea due to the scale problem, meaning that the total amount of power plant emissions will vastly outweigh the need for cement. OTOH just getting rid of existing cement kiln technology (the most intensive sector for CO2 emissions) would be a big step forward.

Wasn't a CO2 consuming concrete featured on The New Inventors a while back? I seem to recall it used magnesia and recycled waste and used CO2 to set - rather than giving off CO2 as well as being energy intensive (CO2 intensive) for production.

Lots of good questions, some of which I would have asked if they hadn't been so many hands up :-) A couple of them I can answer quickly from what I heard, others will take me a while to report on, as this is an area I need to get up on. Needless to say, any information is greatly appreciated.

1) For context, I mentioned R2-D2 at Dot Earth, which is a labeling system for R&D efforts, since "R&D" is widely misunderstood and misused. It's derived by giving my own specific labels to the sorts of phase descriptions used at Bell Labs, noting of course that the boundaries are sometimes fuzzy.

R1: Pure Research, many little projects, modest $
R2: Applied Research
D1: Exploratory Development
D2: Advanced Development
D3: Development, might include pilot plants, beta tests, etc.
D4: Deployment & scaleup, cost reductions, etc. $$$$$$

I assessed this as D2, maybe further, given that they do have one pilot plant. I'd heard of the concrete idea years ago, but it mostly seemed in the R2/D1 stage. For a lot of these things, D4 is the big hurdle, including the issues of whether or not something that works one place works in enough places (not everywhere) to be useful, and the overall economics, acceptance of potential customers, etc. The encouragement towards the latter was:

a) Coming out at World of Concrete

b) Having serious executives on board from concrete & construction businesses.

c) Founder is well-aware of conservatism of the industry. He said something like: "If you thought the doctors were conservative towards new bone cements, you should see the cement business!" But he also claims there was a lot of interest from many people at the conference, which is hard to assess without more data. However, it does mean this is further along than some university experiment (which are usually R1/R2 and maybe D1).

d) Put another way, while at first look I am very interested in this, as it at least sounds like it might scale up in some useful way, and have economics with it, I've been through technology introduction wars too often & heard too many entrepreneur-VC-pitches too many time to think anything is a slam-dunk.

NOW, A FEW QUICK ANSWERS:

re #8 Eli
The Rabett is right that CA uses some electricity from coal. Basically, long ago, CA made it hard to build coal plants inside CA, although some utilities (San Diego & especially Los Angeles snuck around this by getting them built elsewhere. This loophole got closed two years ago, but as it says:

"California, which has only two very small coal plants within its borders, imports about 20% of its power from coal plants in other western states."

Art Rosenfeld is keen to use better roofs to raise albedo, especially relevant in Southern California to reduce air conditioning load, and of course, that's where the biggest use of coal-based electricity is.

If one *has* coal plants, then using fly ash is a really good idea. CA effectively doesn't *have* coal plants here, so shipping fly ash from NM, Nevada, Utah, (or barging from China) doesn't really seem like a great idea.

My local utility is PG&E, which basically uses almost no coal directly, but imports power from other states, a small amount of which comes from coal. It doesn't own any coal plants in CA or anywhere nearby, although oddly, it owns a few on the East Coast.

I'm sure the Rabett knows the difference between "has coal power plants" and "uses electricity from out-of-state power plants" ... but maybe he's looking for a part in a remake of Monty Python and the Holy Grail, and needs to keep his teeth sharp :-)

Finally, the Moss Landing power plant, besides being CA's largest, had a very convenient unused building right next to it, and is about 45 miles from Calera's HQ in Los Gatos. New Mexico is not so convenient.

re #9 & #10 vague & rich

These are all good concerns. Remember that Constantz started research as a coral expert. The first 10 minutes of his talk was a *passionate* concern about damage to coral growth, showing photos of coral reproduction in 1983 that no longer happens in most places. The ocean acidification has been slowing down a natural process that converts Ca and CO2 into hard rock ... under water.

Also, his medical device work has to do with making cements that work well inside human bodies, i.e., lots of water and blood.

I haven't yet looked at the numbers, but I'd guess it would be relatively hard to use so much Ca as to deprive shellfish and corals of it, whereas CO2 increases are already causing trouble. Constantz basically says that we're already interrupting the natural (slow) deposition cycle that normally sequesters most carbon into rock.

Here is Portland cement and White Portland Cement. The Calera product is white, which is probably good for raising albedo.

Here is Calcium carbonate.

A contractor in the audience asked what differences he would see, Constantz said none, except that this stuff was white. He was claiming that basically, one could use their output to augment or replace Portland cement, and to generate aggregates, but based on calcium rather than silicon. He gave a handful of detailed numerical examples of different mixtures and their levels of carbon sequestration. He observed that CaCO3 has (allomorphs? polymorphs?) with very different properties, i.e., the crystal structure really matters, i.e., one should not just think of limestone. (Constantz is sometimes labeled a crystallographer, and certainly, Google Scholar would support that.)

He mentioned that the pyramids have lasted a while and that they have some concrete, not just limestone.

Google: pyramid calcium carbonate concrete

He also claims that using CaCO3 reduces rebar corrosion.

====

I don't know enough about all this chemistry to say anything with strong confidence. I do know that concrete, for all its familiarity, is very complex chemically.

However, Constantz' background and publications tends to lend credibility to the idea that he understands CaCO3 very well, and if he says you can build long-lived built-environment structures out of it, my default is to guess that he's right, until I get more opinions from knowledgable folks. But of course, that gets you into D3.

Does it get you to the (necessary) D4? Are the lessons learned at a gas-fired plant transferable to coal plants? I.e., what about the mercury and other things? (I would have asked that if I'd gotten called.) Which locations are *actually* suitable (of the big maps he showed of coal-fired power plants)? Etc, etc.

(more later on sizes of things. The cement and aggregate business is HUGE, especially right now in Asia. Part of his claim was that if we wanted a sequestration process that really worked, and lasted, it was hard to see how anything but sequestering the CO2 in rock was going to work well enough, because it had to be done on a huge scale, and relatively quickly.)

re: #13 Mark

No direct relationship to air capture. Generally, Calera prefers higher CO2 concentrations and higher Ca/Mg concentrations, i.e., harder water. Only if they ran out of coal and gas plants would they care about air-capture. Of course, IF (very big IF) the capture part of air-capture became practical, I suppose some version of the Calera process might be useful for the sequestration part, although it's nowhere near as synergistic as it might be with gas/coal.

I'd think it would be more likely to build air-capture thingies wherever it was the easiest to sequester the CO2 geologically, like over old oil wells, perhaps.

(rest for amusement only):

re: Mr/Dr: don't worry about it :-)

As I explained in a reply to Deltoid's favorite Viscount, who posted something that used "Dr" Mashey numerous times: at DeSmogBlog:

"I happen to have an earned PhD from a credible university, so I guess I can be called "Dr" ...
but most people I know don't. My wife has one, many of our friends do, 10% of adults in our town do, Stanford (a few miles a way) has masses, and then there are the MD-doctors as well. To call everyone "Dr" would get wearisome. Competent professionals with track records rarely care much. Also, I'd hate to be grabbed on a plane to help with a medical emergency. :-)"

and

"I'd been recruited to work at PhD-dense Bell Laboratories, which *explicitly* discouraged "Dr" in normal usage:

a) With so many PhDs, calling us all "Dr" would just waste a lot of time.
b) But mainly, because what you accomplished was more important than the title.
c) About the only mention of degrees was in external articles, but even there, a bio would say "...PhD. Mr. X...""

A problem is that depending on how you get the Ca and Mg the precipitation generally gives free H in different degrees depending on pH. You could rise the pH by e.g. adding fly ash how much fly ash is available and what does it consist of... fly ash can have really high levels of "heavy metals"... so an important question would be what would happen with that? (we probably don't want to speed up the ocean acidification problem)

re: #17 bob

Thanks for the comments. My bookshelf has plenty of stuff like Heinberg's books, Smil's "Global Catastrophes and Trends", etc ... so these concerns are well-taken. It seems very likely that the current (rich-world) lifestyle is unsustainable for many reasons. [I grew up on a 100-year-old farm, hence learned Liebig's law early, knew about fertilizers, topsoil, etc...]

I have some hope that with enough energy/person, at least some problems are solvable, although it's hard to see how to get there with 9B people. I do believe it might be possible for people to still live reasonable lives.

However, I'd suggest we not derail this thread off into that discussion, which is a legitimate one, but comes up again and again. Maybe Tim would give it a thread of its own, for people who want to debate that, but it would be really nice to have a focussed thread on *this* topic, which is whether CO2 sequestration on concrete makes any sense.

(1) Either we retain a serious technical civilization, say in 2200, or we don't. Barry Brook & I & others had a long discussion about that at Brave New Climate, in which I explain why I don't think a low-tech civilization is a good idea.

(2) In either case, it is very likely that all of the accessible oil&gas will be gone by 2200 (most by 2100), and much of the coal. I'd like to think we'll leave as much coal in the ground as we can, but it's nontrivial to make that happen, regardless of how big coal reserves really are, as that is being argued about lately.

See comments at John Quiggin for that, and maybe "Peak Everything" discussions fit that thread better.

(3) Hence, the issue (of this thread) is whether or not we can sequester enough of the CO2 to keep the climate somewhat tolerable, regardless of Peak issues. If we can't, it only makes the post-Peak world worse.

Of course, the last thing in the world I'd want is for the coal guys to suddenly point at this saying "the problem is solved, now let us build more coal plants." Among other things, I grew up in Western PA (i.e., coal), and there is still mine subsidence, and that's heavenly compared to nearby W VA.

Still, no matter what we do, there are a lot of coal plants that are just not going to be shut down any time soon.

John,

Can I recommend to you a book called "Sustainable Energy - without the hot air". It can be downloaded from

http://www.withouthotair.com/

It is a brilliantly written book and comes to the same conclusion you have. Climate change or no, we will soon run out of fossil fuels. Can we possibly generate enough energy from sustainable sources, or will we require other technologies.

The author goes to quite some effort to paint a broad brushed picture with readily grasped units to really get a handle on the problem.

Riveting reading in my opinion.

> white ... albedo

Paving, instead of black asphalt.

I'm sure recycled asphalt would be a better source of petroleum products than, say, tar sands.

I know the very idea has already got the asphalt paving lobby in a tizzy -- and the asphalt patching lobby too I imagine.

But think of the acreage of roads ....

John & Aiden,

Thanks for the links - will follow up.

re: #18 Steve (and others)

How big could this be?
I.e., assuming that this actually works, is the size big enough to really help?

Following is a lightning order-of-magnitude check, nothing definitive:

The EIA, 2008 says (Figure 76) that 2005 world CO2 emissions were, in GT:

11.0 Liquids, 5.7 Nat Gas, 11.4 Coal, 28.4 Total

I think the world concrete market was ~ 16 GT/year about then, and if they could sequester roughly half a ton of CO2 per ton of concrete (CO2 ==> CaCO3, mostly), that's about 8 GT/year potential ... which is actually noticeable. Like I said, the concrete business is HUGE.

====

[Caveat: I tend to take EIA *projections* with a grain of salt... in particular, if world CO2 rises by 30% by 2030, it's Not Good. But past data seems OK.]

The USA EPA says:

"Current (2004) world total annual production of hydraulic cement is about 2 billion metric tons
(Gt), with production spread unevenly among more than 150 countries. This quantity of cement
is sufficient for about 14 to 18 Gt/yr of concrete (including mortars), and makes concrete the
most abundant of all manufactured solid materials. The current yearly output of hydraulic cement
is sufficient to make about 2.5 metric tons per year (t/yr) of concrete for every person worldwide
(van Oss, 2005)."

Right now, China uses about half of the world's concrete.
Making a Ton of cement generates ~.7-1.1T of CO2.

Concrete = cement + aggregate + water, and Constantz claims they can do both cement and aggregate [i.e., sand/gravel equivalents].

NextBigFuture gives some details of their process, caveats, comparisons.

They claim to be able to sequester (roughly) half a ton of CO2 per ton of cement (or concrete). Then, there is something for the avoidance of the CO2 creation from the usual methods.

I don't know that all these numbers are consistent, but it's enough to be in the ballpark.

"Either we retain a serious technical civilization, say in 2200, or we don't. Barry Brook & I & others had a long discussion about that at Brave New Climate, in which I explain why I don't think a low-tech civilization is a good idea."

I don't see why it can't be high tech, it's really a matter of being less materialistic, less of a throwaway consumerism society etc. Get over the McMansions and such.
We are so wasteful.

I wish Silicon valley would apply all their talents to solving some of our problems instead of inventing new consumer gadgets every year, that soon become obsolete because they invent new gee wiz gadgets continously. Like cell phones with every feature imaginable, but it keeps changing so fast, that it encourages this throw away mentality. Remember when Ma Bell made a phone that would last a lifetime? Maybe that wasn't so bad. Why do we have to buy a new computer every three years in order to use the internet?

It's completely feasable to phase out all our coal plants in the U.S. with CSP with heat storage. This idea of sequestering in concrete sounds promising, but otherwise I don't see how coal with CCS will be able to compete with wind and solar in the future.

It's interesting that few ask what we will make all the synthetic petroleum products from, when we have burned up all the oil. What will lubricate future machines for instance? Imagine how long the oil would last if we had never burned any of it, but only used it as a raw material.

Speaking of desalinization, has anyone heard of this?

"Carnegie Corp, ... has developed a method of using energy captured from passing waves to generate high-pressure sea water. This is piped onshore to drive a turbine and to create desalinated water."

"A series of large buoys are tethered to piston pumps anchored in waters 15 to 50 meters deep (49 to 131 feet). The rise and fall of passing waves drives the pumps, generating water pressures of up to 1,000 pounds per square inch (psi)."

"This drives the turbine onshore and forces the water through a membrane that strips out the salt, creating fresh water in a process that normally requires a lot of electricity."

http://www.reuters.com/article/environmentNews/idUSTRE51401720090205?fe…

The impact of desalinization on coral and shellfish was mentioned, but according to the book "The Carbon Age" by Eric Roston, a bigger problem with acidification might be the shell bearing algae called cocolithophores that he says are crucial to a balanced carbon cycle. When they die, their calcium carbonate shells sink to the sea floor, effectively taking them out of the carbon cycle. They are what produced the chalk deposits in England and elsewhere. Roston says they might produce half the inorganic carbon, or calcium carbonate that falls to the sea floor.
The net effect is that over long time periods they are a major carbon sink, which are ironically threatened by too much CO2 acidifying the oceans. The Carbon Age is a great book, maybe old hat to scientists, but fascinating for a layman like me.

Chemical looping is an interesting idea for fuel combustion that is compatible with CO2 capture

I hadn't realized how much aggregates California must import; surely it adds a lot to the cost considering the transportation distances and the weight of the stuff.

I recently worked on permitting for a San Joaquin Valley hybrid solar-thermal power plant that proposes to burn ag waste at night and on cloudy days to achieve round-the-clock generation. The proposal includes sale of the fly ash to (IIRC) makers of building materials, pottery, etc. If the concept catches it might reduce some of that importing load while providing significant carbon-neutral power. The ash, of course, will be a lot cleaner than that from coal.

re: #30 trollhattan

Yes, if one is serious about this stuff, transport costs and energy are relevant. Last year, we completed a new, very-green Town Center, using low-CO2 concrete, recycled materials from the old town center, eucalyptus wood from trees that had been cut down a few miles away, etc.

The main lesson for me in this is how very large the concrete business is, even here. In China, really huge.

My last notes, for now, especially regarding the other junk that comes with flue gas, and patent.

0) Constantz spoke of criteria pollutants that normally have to be separated out for CO2 sequestration, implying Calera didn't need to do (as much). AS noted, I didn't get a chance to ask, because the other junk has to go somewhere:

a) Into the outgoing water or air.
b) Separated as part of the process.
c) Adsorbed onto the CaCO2, MgCO3.

One hopes that at least some of it goes to c), but I couldn't tell from the talk, and I have no idea about stuff like Mercury & Uranium.

1) The patent application 20090001020 seems to be the key one. Use the handy website pat2pdf to generate a PDF that you can then download, since reading the text alone without diagrams is not fun. It's about 15 pages, is a very broad patent application in a domain where I have no particular expertise to assess whether it hold up or not, but it is worth reading to get a better idea of what Calera is doing. Ignoring the bunch of patent-speak boilerplate, and knowing that charts are always drawn to be as vague as can be to cover as much as possible:

Figure 1 is the general flow diagram

"[0024] ...the CO2 source may be flue gas from coal or other fuelcombustion, which is contacted with the volume of saltwater with little or not pretreatment of the gas...." (CaSO4, MgSO4 desulfurization step if needed)
"In certain embodiments therefore there are multiple sets of reactions products collected at different stages, while in other embodiments there is a single reaction product collected."

"[0027] produce a precipitated carbonate compound composition and an alkaline-earth metal depleted water."

[0028] raise temperature via flue gases, etc

[0029] raise pH to 9 or higher

[0030] in some cases using ash

[0034-37] additives and catalysts to control the CaCO3 polymorphs, i.e., generate different crystal structures

"[0044] In contrast with seeding approaches to precipitation, methods of invention do not generate CO2 during the precipitation process."

[0058-62] above-ground stable forms. Cement. Aggregates.

[0074-] lots of experimental chemistry-speak, materials analysis.

But, nothing obvious about all the junk in flue gas, so I can offer no answer to that one.

Sorry to come late to the party, but there really is a big "gotcha" in this.

If you want to use calcium to sequester CO2, i.e., produce some calcium carbonate CaCO3 using some CO2 from your coal fired power station, you have to start with a source of calcium which isn't already in the form of CaCO3. The Ca in the ocean is either solid CaCO3 (seashells, etc) or dissolved CaCO3.

You can't get the Ca out of the ocean without either releasing the CO2 that the Ca is bound to, or giving the CO2 something else to bind to. There's no way around this. If there's something that you can easily give the remaining CO2 to bind to, why not use that to bind the CO2 in your flue gas instead?

If, on the other hand, you get your Ca from the second most plentiful source - gypsum - CaSO4, you have to deal with the resulting sulphate. What do you do with the sulphate? The easiest thing to bind it with is water, which results in H2SO4, sulphuric acid. How do we sequester the acid, such that it doesn't dissolve more Ca, and release more CO2...

On further thought, there is an easy way around this. We can clear the air of carbon by filling the sea with sulphur. That'll probably be the next Republican talking point.

Calera basically mimics the chemistry of coral formation, unsurprising, given its founder is a coral expert.

SJ states authoritatively that:

"The Ca in the ocean is either solid CaCO3 (seashells, etc) or dissolved CaCO3. You can't get the Ca out of the ocean without either releasing the CO2 that the Ca is bound to, or giving the CO2 something else to bind to."

This is equivalent to saying that coral formation releases CO2, rather than sequestering it into CaCO3.

Does anyone else agree with that conclusion? How would you decide whether that is likely to be true or not?

"This is equivalent to saying that coral formation releases CO2, rather than sequestering it into CaCO3."

No, it isn't. The coral takes calcium ions and carbonate ions from the seawater. The critical thing is that the coral doesn't take calcium from the seawater and combine it with CO2 from the air, it gets the CO2 (CO3--, actually) from the seawater.

Here's my understanding of the whole process. There are rocks containing calcium silicate, e.g. serpentine. Over a long period, rainwater containing dissolved CO2 breaks the calcium silicate down into calcium carbonate and silica. Eventually, some of the calcium carbonate finds its way into the sea, where it either dissolves or not depending on pH. The dissolved calcium carbonate is available for animals to turn into skeletons. There is carbon sequestration involved in the process, but it happened thousands or millions of years ago when the calcium silicate broke down. You can't then use the same calcium to sequester more CO2.

Simpler version: if you want to sequester CO2 from your power station in the form of a carbonate, you can't do it with a material that's already in the form of a carbonate. You have to use something else.

Even simpler: SJ appears not to believe there are Calcium ions (written Ca++ or Ca2+ ) in seawater ... but there are, ~400 ppm.

See
salinity for a table of salt ion concentrations in seawater

and
bicarbonate, which says:

"It is thought that the carbon dioxide in the sea exists in equilibrium with that of exposed rock containing limestone CaCO3. In other words, that the element calcium exists in equilibrium with CO3.

But the concentration of Ca (411ppm) is 10.4 mmol/l and that of all CO2 species (90ppm) 2.05 mmol/l, of which CO3 is about 6%, thus 0.12 mmol/l. Thus the sea has a vast oversupply of calcium."

See also: hardwater.

The Calera patent says "calcium in amounts ranging from 50 ppm to 20,000 ppm," which certainly includes seawater's ~400ppm.

"SJ appears not to believe there are Calcium ions (written Ca++ or Ca2+ ) in seawater ..."

Really? I would have thought it was a bit of a giveaway where I said: "The coral takes calcium ions... from the seawater."

"It is thought that the carbondioxide in the sea exists in equilibrium with that of exposed rock containing limestone CaCO3. In other words, that the element calcium exists in equilibrium with CO3."

This bit I don't disagree with, but would add that limestone is formed from the skeletons of dead animals, and is not chemically different from the skeletons of living animals. If you alter sea chemistry in a way that causes limestone to dissolve, you're also affecting living animals, i.e. coral, molluscs, etc., which is my concern.

I don't understand the rest of the quote. It doesn't make sense to me to say that there's an equilibrium but there's an excess of one side of the equilibrium.

OK, I've read the patent application and the Scientific American article now.

It's difficult to find better adjectives than "rubbish" or "con-job".

All he's proposing to do is to bubble hot flue gas through seawater. Doing this will not cause CaCO3 to precipitate. Just cannot happen. It won't remove any CO2 from the flue gas, either.

He mentions some things like adding CaO2 or Ca2SiO4 and cold liquid CO2 to improve the "efficiency" of the process. The efficiency improvement, from zero to some non-zero value, indicates that the additives are in fact the whole of the process. It's like the [Stone Soup](http://en.wikipedia.org/wiki/Stone_soup) fable.

"All he's proposing to do is to bubble hot flue gas through seawater. Doing this will not cause CaCO3 to precipitate. Just cannot happen. It won't remove any CO2 from the flue gas, either."

On further thought, I've realised that this isn't correct. It is possible to precipitate CaCO3, but it's purely by the application of heat and not through any chemical reaction with the CO2 in the flue gas. If you heat the seawater, you drive out some of the CO2 that was already dissolved in the seawater, which causes some of the dissolved CaCO3 (and other carbonates) to precipitate. This is the same process that causes "scale" to form inside kettles.

So the process may actually have some benefit in pre-processing water destined for a desalination plant, which is what the patent application actually says it's for.

It most definitely will not have any benefit in carbon sequestration.

Another item on this:

article by local Monterey paper, including work with ocean researchers on potential environmental impacts.

Thanks for that John. That's probably the final nail in the coffin.

"Now, all cement must be a blend of 80 percent Portland cement and 20 percent supplementary cementitious material (SCM) â material with cement-like properties.

At the World of Concrete conference in Las Vegas in February, Constantz will present his product as an SCM with an even lower carbon footprint. He hopes builders will gain confidence in his product and begin using blends of 50 percent Calera cement with 50 percent Portland cement â and eventually 100 percent Calera cement."

It's a multi-level con. He's promoting it as:

1) Water softening for de-salination

2) "Green concrete"

3) Carbon sequestration.

(3) is obviously a con.

(2) is also a con. Making portland cement involves reversing the transformation of calcium silicate to calcium carbonate that I mentioned above. That is, you dig up limestone (calcium carbonate), and turn it back into calcium silicate. All he's proposing to do here is to substitute calcium carbonate for calcium silicate. Any cement manufacturer could achieve the same result at lower cost, simply by adding unprocessed limestone to the cement.

(1) might not be a con.

The Calera story sounds good - but upon close examination, and a reading of their patent, it is clear that it is a complete Greenwash.

Their patent application US 20090020044 (search under patent number at http://appft1.uspto.gov/netahtml/PTO/search-a... ). The patent describes taking dolomite/dolomitic limestone and calcining it (releasing CO2) and then reacting this with seawater and CO2 to regenerate calcium/magnesium carbonate!!!

There is very little if any capture of CO2 by their process since the calcining step generates so much CO2, and there is CO2 generated from the processing operations - it is highly probable that the technology has a net positive carbon footprint.

Where is the biological process for capturing CO2? Calera is using decades old and very dirty and polluting chemistry for extracting magnesium/calcium from seawater - a very similar process was used by the magnesium factory which formerly occupied the Moss Landing site.

There is nothing Green about Calera's process - basically, they are burning/calcining limestone, and using it to make artificial limestone from seawater. All smoke and mirrors.

And, Calera's product is no cement - at best it is a poor mineral admixture. The patent shows that at a 20% replacement of Portland cement, the strength is only 50%(3000 psi) of that of 100% Portland cement - to get close to the strength development of Portland cement, the replacement level has to be reduced to 5%. Also, the drying shrinkage is doubled at 20% replacement of Portland cement.

Not only is Calera's product not a cement, but its addition to Portland cement is very deleterious - it greatly reduces strength and increases shrinkage - and almost certainly decreases long-term durability, corrosion resistance, freeze-thaw resistance, etc..

This is very disappointing - first Calera said that it had a 100% replacement for Portland cement that would capture 1 ton of CO2 per ton of cement (impossible, unless the cement is pure CO2!)- they then amended this to a 50% replacement for Portland cement and a carbon neutral cement. Now what - 5% replacement for Portland cement?

Total Greenwash!

And note for comparison that (natural) limestone is commonly used as an aggregate for concrete, and is used as an admixture for cement in Europe at up to 45%.

A quick analysis of Caleraâs process:

Assuming Calera captures calcium and magnesium from seawater as carbonates, one ton of carbonate cement would require at least 500 tons of seawater (> 80% capture efficiency) - or about 300 tons of desalination brine. So, to supply just US cement demand (over 120 million Mt per year), you would need to process 50 billion cubic meters of seawater! The most economic method would be to piggyback the process onto desalination plants, but even with desalination capacity increases, desalination brines could supply at most 6% of US cement demand. And, processing seawater for cement production alone is neither economic (Portland cement sells at $100-120 per Mt in the US) nor environmentally friendly.

Also, such a process will generate a calcium/magnesium-stripped brine rich in sodium/potassium. Many, many studies have shown that such brines have severe environmental impacts when discharged into the ocean - the high salinity kills flora and fauna in the brine plume - so much so that regulations now dictate that such brines have to be diluted with seawater prior to discharge, or have to be landfilled. Also, processing seawater produces large amounts of a toxic sludge containing copper, nickel and chromium (leached from metal piping and processing tanks) as well as cleaning agents and disinfectants (used in daily cleaning operations) â this sludge is highly hazardous and has to be landfilled.

It is puzzling that Calera does not appear to be talking about a biological process, and in fact their patent is a pure chemical process that essentially reprocesses natural limestone to make artificial limestone. Originally, Calera was talking about making calcium/magnesium carbonates via a biological path - ie. use carbonate-forming marine organisms to form magnesian calcite, and collect/process the resulting biomass/skeletons (the precursor to limestone). Of course, the chemistry is such that this product could never be a cement (it does not undergo a hydraulic reacting with water and does not set) â this would explain why Calera has now given up on making a cement (as they had initially claimed). Similarly, this product would be a poor mineral admixture for cement due to its biomass content and the crystalline form of the magnesian calcite â this would explain the poor results reported in the Calera patent application.

Now, presumably as a last-ditch effort to salvage something, Calera is talking about making an aggregate. Well, if you want a strong, resilient and time-tested carbonate aggregate, you simply use limestone. You do not set up a limestone-to-calcined limestone-to artificial limestone process that is dirty and polluting and carries huge environmental consequences, makes a much inferior product to the natural material, and then claim it is Green!

More Greenwash!

Calera must be in dire straits - now they are dissolving olivine in hydrochloric acid and using the Mg/Ca stream from this, along with sodium hydroxide as base, to precipitate CO2.

They have also re-invented the electrolytic cell for the production of sodium hydroxide from brine.

Calera would have people believe that these energy/resource-intensive processes are "Green".

Yet more proof of the Calera Scam.

See their patent application WO/2009/086460 (METHODS OF SEQUESTERING CO2)

Outrageous pseudo-science on Caleraâs website.

Case in point - their projections for CO2 capture by fly ash at their demonstration site in Australia (link is: http://www.calera.com/index.php/case_studies/yallourn_australia/)

Calera claims that they will capture 68,000 tons of CO2 using 50,000 tons of fly ash.

This is patently outrageous. The contents of calcium, magnesium and iron oxides in Australian fly ash are 4-10%, 1-3% and 5-15% w/w. The respective oxides can capture 0.79, 1.10 and 0.55 tons of CO2 per ton of oxide. This means that at the very most, one ton of fly ash could capture 0.07 to 0.19 tons of CO2 per ton of fly ash.

So, at the very most, 50,000 tons of fly ash could capture 9,500 tons of CO2.

Caleraâs figures are completely ridiculous and have no scientific basis or any semblance to reality.

Greenwash is alive and well at Calera.