Could novel technique to curb global warming also trigger earthquakes?
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.Skip to next paragraph
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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.
The topic was part of a broader discussion about earthquakes and energy-related activities at a Senate Committee on Energy and Natural Resources hearing Tuesday. The hearing was tied to the release last Friday of a report on whether hydraulic fracturing – forcing fluids under high pressure into certain shale formations to crack the rock and release the natural gas – could increase the risk of earthquakes.
That report, by the National Research Council, concluded that "fracking" presented little risk of triggering quakes that could be felt at the surface. But it added that injection wells used to dispose of waste from fracking and other forms of oil and gas extraction posed a higher risk of triggering temblors than fracking itself. The study pointed out that little was known about the quake-triggering potential of carbon capture and storage.
Carbon capture and storage has long been considered a potentially potent arrow in the greenhouse-gas-control quiver. In the United States, the climate bill Congress considered but failed to pass in 2009 would have invested some $60 billion by 2025 in research and demonstration projects.
Globally, 29 large-scale sequestration projects at power plants have been undertaken during the past several years, according to a database maintained by the Carbon Capture and Sequestration Technologies program at the Massachusetts Institute of Technology in Cambridge. Of those, 10 are in the US but four have been canceled, largely due to a rocky economy and uncertainty regarding US climate policy.