You say Calera, I say Caldeira

Folks,

As I have said before, I am not asking Calera to tell us proprietary process information. We can treat their process as a black box, but they at least need to answer the question:

What are the inputs to and outputs from their proposed process, including quantitative information that would allow independent evaluation of the "in-principle" thermodynamic and mass-balance characteristics of their proposed process?

How can they represent themselves as having an effective carbon storage technology if they will not even be forthcoming with this basic information? I am not asking for secrets of what goes on inside their black box. I just want to know what goes into the box and what comes out. Every other related proposed process is upfront and forthcoming about this basic level of information (cf. House et al, Lackner, Keith, Rau et al., etc).

I am completely unconcerned about infringement of the Rau and Caldeira patent by Calera, especially since Calera's supposed process makes no sense to me. But just to clear up any impression that I am asking Calera to come clean in an effort to gain personally, in the unlikely event that that patent should ever make any money, I have publicly stated that I will donate 100% of my share of the proceeds to non-profit charities and NGOs.

My goal is simply to cut down on the level of misinformation. I would love nothing more than for me to be wrong and for Calera to have figured out a process that will make a major contribution to solving the carbon climate problem. If Calera's process is so wonderful and above board, why won't they be forthcoming with the basic information needed to evaluate whether their proposed process makes any sense "in principle"? What are they hiding?

Best,
Ken Caldeira

Ryan,

Thank you for the interesting article. I have met Ken, and he's a great researcher, he won't mind a bit. But please correct Ken's surname to "Caldeira", see: http://globalecology.stanford.edu/DGE/CIWDGE/labs/caldeiralab/

Thanks,

David
_____________
David Andresen
Director of Corporate Finance - Cleantech Group
www.oraclecapital.com

A couple of comments.

1) Neither Brent Constantz nor Calera have any expertise in metabolic/pathway engineering - I know this first-hand.
2) The use of an engineered microbe does not enable the production of a cement from carbon dioxide and seawater - all you can do is produce carbonate, or more correctly, carbonate/carbonate-directing protein composites (carbonate biominerals, skeletons, etc) - these are thermodynamically stable composite materials which have no cementing activity. In other words, you cannot produce a cement from carbonate biominerals (they will not “set” into a cement, since they are preformed cements) - you would have to convert them into a reactive/metastable state, and Calera has no know-how or technology for doing this.
3) We have examined the Calera patents - it is a dirty, CO2-producing chemistry of the worst type - and is anything but “Green”. They take limestone, calcine it (releasing CO2), and react it with CO2 (flue gas) and seawater to reform limestone. This is not Clean Technology - it is Snake Oil. The patent vividly demonstrates how abysmal Calera’s technology is.
4) Finally, the nature of Calera is clearly demonstrated by their publicly documented statements and press releases. Brent Constantz and Vinod Khosla first claimed they had a 100% replacement for Portland cement, and that their cement would sequester 1 ton of CO2 for every ton of cement produced (impossible, unless their cement is pure CO2). They then said that their cement would be used at 50% replacement level for Portland cement and that it would sequester 0.5 tons of CO2 for every ton. Then late last year they changed their story again - no cement - instead they are producing aggregate. Now Brent is saying that he never claimed a cement product.

What we have seen from Brent and Vinod is a steady stream of pseudo-scientific hot air and untruths without any scientific basis. They clearly do not have a cement, their process is a Greenwash and their mode of operation is repugnant.

We commend Ken Caldeira for his principled stand - he has done the public, the industry and the scientific community a great service by exposing the Calera scam.

A quick analysis of Calera’s seawater 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) – 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) – 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 – 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!

gwash -

You post the same thing in multiple places, and there are a few things that should be pointed out.

1) Your numbers may be correct about the amount of water that would need to be processed to replace all cement in the US. But, who said they were going to replace it all? And, if they DID replace it all, wouldn't that then be a monopoly and raise more issues?

2) Do you know everyone at the company? Maybe there are some people there who know metabolic things. Besides, there is no guarantee they are using bacteria or microbes or whatever for this process. The two patents that are published are on a) carbonates in cement (US20090020044) and b) precipitating carbonates (US20090001020). Maybe they are using biological means, but we don't know for certain.

3) You should really re-read the '020 patent. They do not say they calcine the CaCO3 to form CaO and then react that with CO2 to form CaCO3. What they say is: "[0075] 25 g of granulated (Ca,Mg)O (a.k.a., dolime or calcined dolomite) was mixed into the seawater." The phrase "also known as" does not mean the same thing as "this is how we got it." I could say, "I like to eat cookies (a.k.a. baked cookie dough)" and that would not mean I somehow unbake the cookies only to bake them again before I eat them.

4) If you don't agree with me on point #3, you should read the reference so kindly pointed out by Ken Caldeira (i.e. Kheshgi 1995) in some of his posts. Figure 1 in the paper presents one scheme for sequestering CO2. "The production of 1 mole of CaO requires 0.41 mole of carbon in coal, and 1 mole of CaCO3. Combustion of C and decomposition of CaCO3 results in 1.41 moles CO2 emitted to the atmosphere. For each mole of CaO dissolved in the ocean, 1.79 moles of CO2 are absorbed by the ocean resulting in a net removal of 1.79-1.41 = 0.38 mole CO2 per mole CaO produced."

I think these points should satisfy all your arguments against Calera. I'd love to hear your thoughts.

KC -

I don't quite understand what you like when you say:

"What are the inputs to and outputs from their proposed process, including quantitative information that would allow independent evaluation of the 'in-principle' thermodynamic and mass-balance characteristics of their proposed process?"

and at the same time:

"I am not asking Calera to tell us proprietary process information."

Wouldn't one be the same as the other? I agree it might be nice to know inputs/outputs, but wouldn't part of the proprietary process include inputs and outputs?

Response to Unknown User:

What are you talking about? The chemistry is very clear - when the Calera patent refers to(Ca,Mg)O it is a clear reference to calcium/magnesium oxide (eg. calcined Dolomite) - cemistry dictates the use of the reactive oxides (or hydroxides) for carbonation reactionas at room temp. Whether Calera makes the oxide or buys it from a vendor is immaterial - its production has a large CO2 footprint - from the chemical release of CO2 from the carbonate and from the energy input for calcination.

Yes - the calcination of CaCO3 to CaO results in the net release of about 1.4 - 1.5 mol of CO2 per mol of CaO produced. Of course, you can re-react the CaO with CO2 - you would re-capture 1.0 mol of CO2 (at 100% carbonation efficiency), incur an energy expenditure equivalent to 0.1-0.15 mol of CO2 per mole of CaO for performing the pressurized carbonation - so the net process would have a positive carbon footprint of about 0.5 mol of CO2 per mole of CaO/CaCO3. There is a large net production of CO2. This is no surprise. So - what is your point???

To characterize this debate as "a battle between venture capital and academic science" ignore the fact that Dr. Constantz is a Scientist of high acedemic prestige, particularly in the area of cements.

Personally, I believe that Dr. Constantz is motivated to sequester carbon by his strong desire to save the coral. It cannot be ignored that he is a marine biologist by training (specializing in coral). I don't see why he would persue this technology if it wasn't a promising path to sequestration.