Trapping Carbon Dioxide in Stone

Iceland Geothermal Power PlantBy Nick Stockton


Carbon dioxide is a problem. And everyone knows the best thing to do with problems is bury them deep in the ground and forget they ever existed.

Practical-minded environmentalists and coal sympathizers alike have long touted carbon capture and underground storage as a low-emissions way to help the world’s economy wean itself off fossil fuels. But extracting the troublesome greenhouse gas from power plant emissions is usually way too expensive to be worthwhile. Plus there’s the fear that the stuff might leak from its tomb. But a plant in Iceland might have found a solution. By pumping the stuff into volcanic basalt, the CarbFix Project has converted 95 percent of the CO2 emissions from a geothermal plant into solid carbonate minerals.

A miracle!? Not quite. But we’ll get to that in a second. First you should know a few things about typical, high-investment carbon capture and storage—for starters, that carbon isn’t captured (sadly) by tying giant balloons around smoke stacks. “It turns out it is captured chemically rather than physically,” says Bill Moomaw, lead author of a 2005 IPCC report on carbon capture and storage. Carbon-scrubbing power plants equip their exhausts with filters with amines that bind carbon dioxide molecules.

After capturing the CO2, plant operators have to release it from the amines by raising the temperature until the CO2turns back into a gas. Then they cool it down again—down to like -30, -40 degrees Fahrenheit—so it becomes a liquid that can be pumped into a subterranean cavern. Hopefully that cavern doesn’t leak, because the carbon dioxide could need anywhere from hundreds to thousands of years to turn into limestone.

Continue to full article . . .

Picture: Hansueli Krapf [CC BY-SA 3.0 (, via Wikimedia Commons

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