Carbon storage - how it could work

Last year we had a good laugh at politicans who were saying America could be powered by "clean coal." What they were talking about, what they are still talking about, is carbon capture and storage (or sequestration). CO2 would be captured at the source, then -- disposed of. Somehow.

Of course this does nothing about the other part of the coal idiocy, the input side.  The environmental disaster caused in the course of mining coal is enough by itself to take coal generated electricity off the table. 



But coal is not the only source of manmade CO2, and from a practical standpoint it could be a long time until all these sources are eliminated.

Thus the interest in sequestration. But couldn't developing such technologies take some of the urgency out of converting economies to sustainable power? Yes, it could. But it's also possible that strong environmental policy plus availability of sequestration technology could get us to big GHG reductions sooner.

So what is the science behind carbon sequestration?

There are a number of competing concepts being studied, but they all involve mimicking natural processes.  Soil, forests, grasses, oceans and algae all absorb or process CO2, some more quickly or effectively than others.  For example, there is evidence saltwater marshes absorb more CO2 than equal areas of freshwater wetland (many of the latter also emit a lot of methane).

Another method is the focus of much interest: geologic sequestration.  It is known that when CO2 contacts basalt rocks, a reaction occurs that causes the CO2 to mineralize, forming magnesium and calcite.  Scientists think that massive amounts of CO2 can be injected into a field of fractured basalt, and that the CO2 would mineralize in 4-6 weeks.

At the Pacific Northwest National Laboratory, Dr. Pete McGrail (yes, he's heard all the Holy McGrail jokes) has been studying CO2-basalt reactions in the lab, and has designed an experiment to test it in the field.  He plans to inject CO2 3000 feet into a large zone of basalt in the Columbia River Basin of central Washington. Geologic pressure will liquefy the CO2 (McGrail has found a greater reaction with liquefied CO2), which will mix with groundwater and then mineralize in reaction with basalt.  Samples will be taken after 6-8 months and 1.5 years to measure how much CO2 has mineralized.

A different experiment is planned for Iceland. That country generates a lot of geothermal power, but doing that releases some CO2 from deep in the Earth. The experiment, "CarbFix," intends to capture that CO2, dissolve it in water, and inject it into basalt at a site in southwest Iceland.

Huge fields of basalt are present in places like Siberia and the Decca region of India.

Flood basalts and oceanic basalt fields (Short, N.M., in Remote Sensing Tutorial, sec. 17-3, Federation of American Scientists, 2005)

Links
The PNNL project 
The Iceland project