Carbon capture and storage (CCS) is designed to help coal plants and other installations reduce the amount of CO2 in the atmosphere by isolating the CO2 before it goes up the smokestack, pressurizing it, then injecting it into the ground. It’s an unproven technology on a large scale, expensive, and as some analysts say, necessary to help coal-fired power plants comply with the Environmental Protection Agency’s (EPA) stringent rules on carbon emissions.
Further fueling the debate on CCS is research that shows the process CCS could cause earthquakes.
‘High Probability’ of Earthquakes from ‘Large’ CO2 Injections.
In a 2012 study, Stanford University’s Mark D. Zoback and Steven M. Gorelick assert that “there is a high probability that earthquakes will be triggered by injection of large volumes of CO2 into the brittle rocks commonly found in continental interiors. Because even small- to moderate-sized earthquakes threaten the seal integrity of CO2 repositories, in this context, large-scale CCS is a risky, and likely unsuccessful, strategy for significantly reducing greenhouse gas emissions.”
The assertion by the Stanford researchers prompted the Washington-based newspaper the Kitsap Sun to draw a parallel to research at a West Texas oil field that “experienced 93 earthquakes in 2009 and 2010, some of which were Magnitude 3 or greater.”
Seismologists Wei Gan of China University of Geosciences and Cliff Frohlich of the University of Texas-Austin found that from 2006 to 2011 earthquakes occurred near the Cogdell oil field near Snyder, Texas.
“A previous series of earthquakes occurring 1975 to 1982 was attributed to the injection of water into wells to enhance oil production,” they wrote in the Proceedings of the National Academy of Sciences journal. “Water injection cannot explain the 2006–2011 earthquakes.”
Not The Water, the CO2.
Gan and Frohlich noted that since 2004 significant amounts of gas, including carbon dioxide, had been injected into the Cogdell wells.
“If this triggered the 2006-2011 seismicity, this represents an instance where gas injection has triggered earthquakes having magnitudes of 3 ane larger,” they wrote. “Understanding when gas injection triggers earthquakes will help evaluate the risks associated with large-scale carbon capture and storage as a strategy for managing climate change.”
The Cogdell oil field was flooded from 1957 and 1982 to boost the petroleum production and “a contemporary analysis concluded this induced earthquakes that occurred between 1975 and 1982,” Gan and Frolich wrote. The National Earthquake Information Center detected no further activity between 1983 and 2005.
Seismograph stations deployed by the USArray program identified 93 earthquakes occurring between March 2009 and December 2010 in the vicinity of the Cogdell field.
Not That CSS Does, But It Could.
“I was surprised when I found the quakes in West Texas appear to be caused by carbon injection,” Frohlich told the Kitsap Sun, adding that the study doesn’t prove that CCS projects necessarily cause earthquakes, just that they could.
“It’s not a smoking gun,” said Wayne Pennington, interim dean of the College of Engineering at Michigan Technological University, who reviewed Gan and Frohlich’s paper prior to publication. “It’s not going to happen everywhere. It does not mean you cannot do carbon sequestration. It removes one level of uncertainty.”
MIT Weighs In.
After the Zoback and Gorelick study was released, two MIT professors and an MIT engineering researcher wrote in a letter to the Proceedings of the National Academy of Sciences that there is “no geologic evidence that seismicity causes fault leakage that would render large-scale carbon capture and storage unsuccessful.”
The MIT researchers argued that Zoback and Gorelick “referred to laboratory studies on granitic rocks — conditions that are not relevant for CCS. In reality, large volumes of buoyant fluids have remained stable in geologic traps over millennia in regions experiencing strong and frequent earthquakes, like southern California, even under substantial overpressures.”
The MIT group added that site selection is important for CCS storage. “Although there are geologic settings in which induced earthquakes and leakage risk could compromise a CCS project,” they wrote, “(the Zoback and Gorelick study) says nothing about the many geologic formations that exhibit excellent promise for storing CO2.
“We do not argue that the issues they raised are immaterial, but rather, that more work on the physics of induced seismicity, fault activation, and geologic characterization in the context of CCS is needed.”