Underground heat is typically mined by pumping water into the earth, then bringing it back up hot to power turbines that generate electricity. But carbon dioxide can outperform water: The greenhouse gas extracts heat about two to four times more efficiently. In a computer simulation, researchers found that compared with an average geothermal plant, a carbon dioxide-fed geothermal plant could produce 10 times more power while also locking away the annual carbon dioxide emissions from as many as three midsize coal-fired power plants.
Preliminary tests of the technology, called carbon dioxide plume geothermal (CPG), are underway. Meanwhile, researchers are also looking for other ways to use carbon dioxide in tandem with renewable energy. “We need to reduce carbon dioxide emissions, and expand and develop renewable energy technology,” says Bielicki. “What I really like about my research is it combines the two.”
[This article originally appeared in print as "Geothermal's CO2 Boost."]