Argument: Risks of stored CO2 leaking is very low
John Deutch, PhD, Institute Professor of the Department of Chemistry at the Massachusetts Institute of Technology, and Ernest J. Moniz, PhD, Director of Energy Studies at the Laboratory for Energy and the Environment at the Massachusetts Institute of Technology, stated in their 2007 study, "The Future of Coal: Options for a Carbon-Constrained World," available at www.web.mit.edu: "In order to achieve substantial GHG reductions, geological storage needs to be deployed at a large scale...A number of geological reservoirs appear to have the potential to store many 100's – 1000's of gigatons of CO2. The most promising reservoirs are porous and permeable rock bodies, generally at depths, roughly 1 km, at pressures and temperatures where CO2 would be in a supercritical phase. Once in the pore, over a period of tens to hundreds of years, the CO2 will dissolve into other pore fluids, including hydrocarbon species (oil and gas) or brines, where the CO2 is fixed indefinitely, unless other processes intervene. Over longer time scales (hundreds to thousands of years) the dissolved CO2 may react with minerals in the rock volume to precipitate the CO2 as new carbonate minerals... [I]t is very likely that the fraction of stored CO2 will be greater than 99% over 100 years, and likely that the fraction of stored CO2 will exceed 99% for 1000 years... Since CO2 is buoyant in most geological settings, it will seek the earth's surface. Therefore, despite the fact that the crust is generally well configured to store CO2, there is the possibility of leakage from storage sites. Leakage of CO2 would negate some of the benefits of sequestration. If the leak is into a contained environment, CO2 may accumulate in high enough concentrations to cause adverse health, safety, and environmental consequences. For any subsurface injected fluid, there is also the concern for the safety of drinking water. Based on analogous experience... these risks appear small... Our overall judgment is that the prospect for geological CO2 sequestration is excellent. We base this judgment on 30 years of injection experience and the ability of the earth's crust to trap CO2... The DOE should launch a program to develop and deploy large-scale sequestration demonstration projects."