A report finds that injecting carbon dioxide into underground rock formations, while a potential means of fighting global warming, could increase stresses on faults, leading to earthquakes.
Capturing carbon dioxide from smokestack emissions and pumping it deep underground may not be as useful a tool for dealing with rising greenhouse-gas levels as advocates suggest, according to a new analysis.
The reason: Rising pressure from the enormous amounts of CO2, which would have to be stored for centuries to a few thousand years, could trigger earthquakes. The temblors might do little more than rattle Grandma's china at the surface, but they still could be strong enough to crack rock above the formations used for storage, providing pathways for the buoyant CO2 to leak back into the atmosphere.
Moreover, while some underground formations are well suited for sequestration, they could represent far less storage capacity globally than required if the approach is to be a significant tool for holding down atmospheric concentrations, according to Mark Zoback, a geophysicist at Stanford University in Palo Alto, Calif., and the lead author of the analysis, which appears in this week's Proceedings of the National Academy of Sciences.
Carbon capture and storage "is generally a good idea and can be done safely in many places," Dr. Zoback says. "But we question whether it's a practical thing to do" at the scale of storing 1 billion tons of CO2 a year, which would be needed to help bring CO2 emissions down to 2000 levels by midcentury.
"The volumes that would have to be injected are so enormous ... and in many parts of the world being considered it may well be impossible because of the triggered-earthquake problem," he says.
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