Fossil fuels seem to be running out of places to go. Back in March, officials in Ohio put new restrictions on the natural gas drilling method called fracking after seismologists linked it to earthquakes, and last Friday the National Research Council issued a report detailing the impact of conventional gas and oil drilling on seismic events, along with other underground activity including carbon sequestration. Now a whole new report focuses squarely on the risk of earthquakes from underground carbon sequestration. That apparently closes the door on what was supposed to be an effective way to manage greenhouse gas emissions… or does it?
Carbon in, carbon out…
The new report was prepared by Mark D. Zobackand and Steven M. Gorelick of the departments of Geophysics and Environmental Earth System Science at Stanford University. Aptly titled “Earthquake triggering and large-scale geologic storage of carbon dioxide,” it is a response to the Intergovernmental Panel on Climate Change, which in 2005 proposed underground carbon sequestration as a viable strategy for reducing greenhouse gas emissions from coal-burning power plants and other industrial sources.
Unfortunately, it looks like this strategy could be a classic case of the cure being worse than the disease. According to the report, underground sequestration is highly likely to trigger earthquakes, which would crack open the formation and enable the carbon dioxide to leak out to the surface.
The problem, as identified by the working group, is that most rock formations under continental land masses are too brittle.
“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.”
Not the end for carbon sequestration
The report doesn’t rule out any underground storage, but it does suggest that appropriate sites are not as widespread as previously supposed.
One avenue of exploration is the use of depleted gas reservoirs. While not entirely risk-free, these formations once stored gas, so they could be more likely to have the potential for holding a firm seal.
This past January, the Lawrence Berkeley Laboratory reported that a demonstration gas reservoir project undertaken in Australia has been successful so far, but further study is needed before putting the practice into widespread use.
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