Seeker Blog

Roger Pielke, Jr. notes the NY Times coverage of the Martin & Kubic work at Los Alamos National Laboratory [to be presented at the Alternative Energy Now conference in Lake Buena Vista, Fla.] . Roger references his earlier 2005 post on air capture, which includes references to other ongoing air capture research. In 2005 he wrote:

…Currently air capture of CO2 is a political third rail of climate policy. Here is why:

For most of those people opposed to greenhouse gas regulation advocating air capture would require first admitting that greenhouse gases ought to be reduced in the first place, an admission that most on this side of the debate have avoided. When so-called climate skeptics start advocating air capture (which I have to believe can’t be too far off), then you will have a sign that the climate debate is really changing.

If such a transformation occurs, then we have the irony of seeing the climate skeptics become the technology advocates and the greenhouse gas regulation advocates become technology skeptics. Why? For most of those people who support greenhouse gas regulations, even admitting the possibility of air capture is anathema, because it would undercut the entire structure of the contemporary climate enterprise…

Air capture is not a new idea, as you’ll see from Roger’s references and from the NYT article. Like most large-scale, new engineering concepts — you have to do it to prove out the real-world economics. For scale, imagine building large numbers of new gasoline refineries — large scale chemical plants that have to exhibit high up-time and reasonable maintenance costs.

Since I first looked at air capture I’ve been intrigued with the economics of applying the same chemical plant to a concentrated CO2 stream. E.g., to the CO2 effluent from a coal-fired power plant. If the process makes gasoline from air at competitive prices, it should be somewhat cheaper using the concentrated CO2 stream. If that is true, would it make sense to cluster coal-generation + air capture plants? Where the CO2 conversion plant takes part of its input from the coal-fired plant.

Here’s Roger:

In the New York Times Kenneth Chang reports on a novel application of air capture of carbon dioxide that promises carbon neutral gasoline forever. If commercially viable the technology could prove enormously disruptive to all sorts of interests.

…If their economic numbers are even close to the mark then air capture is coming to a refinery near you. Are you ready?

and an excerpt from the NYT article:

The idea is simple. Air would be blown over a liquid solution of potassium carbonate, which would absorb the carbon dioxide. The carbon dioxide would then be extracted and subjected to chemical reactions that would turn it into fuel: methanol, gasoline or jet fuel.

This process could transform carbon dioxide from an unwanted, climate-changing pollutant into a vast resource for renewable fuels. The closed cycle — equal amounts of carbon dioxide emitted and removed — would mean that cars, trucks and airplanes using the synthetic fuels would no longer be contributing to global warming.

Let’s assume the air capture concept proves to be economical, practical. That doesn’t mean that we should stop converting the majority of planned new coal-fired generation over to advanced nuclear power.

Note: It will be interesting to see how the economics of such as the Martin & Kubic process compare to CCS [carbon capture and sequestration]. In the former case CO2 is treated as a valuable chemical feedstock. That sounds like a more sensible strategy than burying CO2 in geologic strata and hoping most of it stays there long enough. The NYT article closes with this quote:

“It’s definitely worth pursuing,” said Martin I. Hoffert, a professor of physics at New York University. “It’s not that new an idea. It has a couple of pieces to it that are interesting.”

So far I’ve found at Los Alamos National Laboratory this press release, and a summary article [Nov 2007, PDF], which includes some very useful chemical process flow diagrams. Excerpt:

Green Freedom™ consists of two major parts: synthesis-gas production and synthesis-gas conversion. The new and unique technologies and processes developed for Green Freedom™ reside primarily with synthesis gas production. Synthesis gas production is endothermic, so it requires significant power assistance. Synthesis-gas conversion relies on commercially available technology to convert the synthesis gas into useful products. Most synthesis-gas conversion processes are highly exothermic, so the excess heat can be integrated into the system’s operation.

…The conventional thermal stripping process for recovering the captured carbon dioxide from the absorbent, consumes too much energy to be practical. Green Freedom™ uses a newly-developed electrolytic stripping processes that is very selective. It also produces hydrogen as a byproduct that reduces supplemental hydrogen production requirements by 33%. These are key enabling features for Green Freedom™.

Cooling and capture would both be performed in a single cooling tower enhanced to increase air/water contact a modest amount. When compared with the use of a separate absorber tower that is solely dedicated to capturing carbon dioxide, this novel process-integration scheme reduces capital costs by ~90%, capture energy requirements by ~98%, and evaporative water losses by a significant amount.

The new electrolytic stripping cell drastically reduces the energy needed for stripping carbon dioxide from the carbonate solution so that stripping is practical. We estimate that the process would consume ~410 kJ/mole CO2 of electricity and ~100 kJ / mole CO2 of low-level heat energy. Taking credit for supplemental hydrogen production avoidance due to the cell’s hydrogen byproduct, the net electrical energy consumption is ~55 kJ/mole CO2 recovered. The new stripping process requires ~96% less energy than a conventional thermal-stripping process. Furthermore, new materials are emerging that would reduce the capital cost of electrolytic stripping cells substantially,vi below what we assumed in our economic analysis.

The technical risks associated with the new carbon-dioxide capture and recovery process, are related to unverified performance characteristics of the unit operation. Data exist that confirm operability, but additional data are needed to verify efficiency, determine side-stream demineralization requirements, and identify ultimate life-limiting aspects.