Instead of smokestacks belching carbon into the air, plants and factories in Iceland may soon have well injectors to push the greenhouse gases underground. You might think this would inflate the Earth like a balloon and lift it out of orbit (okay, you probably don’t think that, but it’s a good image). But in fact, once it’s injected into Iceland’s basalt bedrock, the carbon combines with other elements to form rock.
This Medusa-like effect is achieved by first sequestering carbon dioxide from geothermal plant emissions, which are mostly steam since geothermal is a renewable resource. Then the CO2 is dissolved in water, which turns it into carbonic acid, and pumped into the basalt. As it flows through the rock, the carbonic acid picks up calcium and magnesium, and turns into new rocks like limestone.
This project is only in the testing phase (I feel like I have to add that caveat every time I write about an awesome idea). Sifting out the carbon from emissions has been challenging, and hydrogen sulfide, one of the non-carbon byproducts of geothermal power, proved corrosive to the equipment. But it has potential — at least in Iceland, with its extensive underpinnings of volcanic rock. Then again, Iceland is so geothermal-heavy that compared to most other countries, they barely need a carbon solution.
New Storage Projects Turns CO2 into Stone, Scientific American.