Storing carbon dioxide underground by turning it into rock

Lab studies on basalt have shown that the rock, which formed from lava millions of years ago and is found throughout the world, can rapidly convert CO₂ into stable carbonate minerals. This evidence suggests that if CO₂ could be locked into this solid form, it would be stowed away for good, unable to escape into the atmosphere. But what happens in the lab doesn't always reflect what happens in the field. One field project in Iceland injected CO₂ pre-dissolved in water into a basalt formation, where it was successfully stored. And starting in 2009, researchers with Pacific Northwest National Laboratory and the Montana-based Big Sky Carbon Sequestration Partnership undertook a pilot project in eastern Washington to inject 1,000 tons of pressurized liquid CO₂ into a basalt formation.

After drilling a well in the Columbia River Basalt formation and testing its properties, the team injected CO₂ into it in 2013. Core samples were extracted from the well two years later, and Pete McGrail and colleagues confirmed that the CO₂ had indeed converted into the carbonate mineral ankerite, as the lab experiments had predicted. And because basalts are widely found in North America and throughout the world, the researchers suggest that the formations could help permanently sequester carbon on a large scale.

The authors acknowledge funding from the U.S. Department of Energy; the National Energy Technology Laboratory; the Big Sky Carbon Sequestration Partnership; Shell Exploration & Production Company; Portland General Electric; and Schlumberger Inc.