Earthquake risk for carbon capture and storage schemes

Move over fracking: carbon capture and storage schemes (CCS) are more likely to trigger earthquakes, warns the US National Research Council (NRC). Meanwhile, a separate study warns that quake-fractured rocks could undermine CCS efforts by allowing the trapped gas to leak back into the atmosphere.

Carbon sequestration involves pumping CO₂ at high pressure below ground and trapping it in porous rocks at depths of 1 to 4 kilometres. Similar deep injection wells are used to dispose of waste water, but despite the large number of such wells, "very few [seismic] events have been documented over the past several decades", writes an NRC panel in a new report, Induced Seismicity Potential in Energy Technologies.

However, carbon capture and storage could see billions of cubic metres of fluid injected below ground ? potentially enough to trigger more and larger quakes, the report concludes.

Even if those quakes do not damage property or put lives at risk, they could undermine carbon capture schemes, says Mark Zoback, a geophysicist at Stanford University in California. "If you trigger an earthquake, you are threatening the seal of the repository," he says. "CO₂ is buoyant and it wants to rise and get out."

Although it is possible to find good sites to store CO₂ where its added pressure would be unlikely to cause quakes or leaks, too few are available to handle the required volume, Zoback says. Older sedimentary rocks in the central US, where most power plants are located, are brittle and so are more likely to fracture and leak. Large-scale carbon capture and storage "is a risky, and likely unsuccessful, strategy" for controlling greenhouse warming, Zoback says. He presented his concerns yesterday to the Senate Energy Committee.

"It's quite possible that quakes may be induced, but that doesn't mean that all the CO₂ leaks out," says Stuart Haszeldine, a carbon capture and storage researcher at the University of Edinburgh, UK.

Plenty of quakes have been measured in the eastern and central US in the past century, he says, but oil and gas remains to be extracted from wells in the area. "If a few per cent leaks out over 10,000 years, it's unfortunate, but it's not terminal to the future of carbon capture," he says. "We need to work out how to manage it."

Journal reference: Zoback's study is published in the Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.1202473109

If you would like to reuse any content from New Scientist, either in print or online, please contact the syndication department first for permission. New Scientist does not own rights to photos, but there are a variety of licensing options available for use of articles and graphics we own the copyright to.

Have your say

Only subscribers may leave comments on this article. Please log in.

Only personal subscribers may leave comments on this article

Subscribe now to comment.

All comments should respect the New Scientist House Rules. If you think a particular comment breaks these rules then please use the "Report" link in that comment to report it to us.

If you are having a technical problem posting a comment, please contact technical support.

smokey robinson pulmonary embolism packages camila alves albrecht durer dan marino david lee roth