Stashing carbon dioxide underground is a much-debated approach to combating rising greenhouse gas levels, and is being tested in California, but is often criticized for its hefty price tag. Now, there may be another fatal flaw in carbon capture and storage. A new paper by Stanford University geophysicist Mark Zoback says the process would likely cause earthquakes that allow the gas to escape back into the atmosphere.
“Beyond economics,” wrote Zoback, “there is a potentially serious geological issue that threatens the viability of large scale CO2 sequestration, which may not be technically solvable, at any cost – the likelihood that injection of enormous volumes of CO2 into the subsurface will trigger intraplate earthquakes.”
Proponents of carbon capture and sequestration espouse collecting CO2 where it is produced, at coal-fired power plants for example, and then pumping the compressed gas into underground natural geologic formations, where it would be stored indefinitely. Over hundreds to thousands of years the CO2 would mineralize into calcium carbonate, also known as limestone.
There’s significant potential for storing CO2 in California, according to West Coast Regional Carbon Sequestration Partnership (WESTCARB), a consortium of government agencies and energy companies funded by the DOE to investigate the technology’s potential statewide. They estimate there’s enough space in California to store 1,800 to 6,600 years’ worth of emissions produced by our current power plants.
WESTCARB worked for seven years to implement a carbon capture and storage pilot project in Solano County, but said they gave up this year for business reasons. They continue to pursue two larger projects in the Central Valley.
According to Zoback, sufficient evidence suggests that pumping huge volumes of the gas underground, as would be necessary to stem global warming, could cause small intraplate earthquakes. Most earthquakes occur at the boundary of two tectonic plates, while intraplate activity takes place along fissures within the plates.
He wrote, “While the seismic waves from such earthquakes might not directly threaten the public, small earthquakes at depth could threaten the integrity of a CO2 repositories, expected to store CO2 for periods of hundreds to thousands of years.”
In essence, the CO2 could escape, negating any environmental benefits promised by the expensive process. An abstract of Zoback’s paper was presented this week at the American Geophysical Union’s annual conference underway in San Francisco. WOW is in the process of obtaining the full paper.
