Is there proof that CO2 storage is safe?
2 storage projects, assuming that sites are well selected, designed, operated, and appropriately monitored, the balance of available evidence suggests it is likely that the fraction of stored CO2 retained is more than 99% over the first 1,000 years (IPCC, 2006).
In the petroleum producing areas of the United States, oil and gas deposits, as well as naturally occurring CO2 gas, have been trapped within subsurface geologic formations for millions of years. These deposits prove that it is possible to store CO2 in geologic formations for very long periods of time. These deposits also provide the understanding of geologic conditions needed for secure storage in areas where these natural deposits are absent. The United States is also fortunate to have extensive experience with natural gas storage, where gas is injected underground during the summer and then recovered to heat homes in the winter. That geological and engineering experience can be applied to CO2 storage. CO2 is a safer, non-combustible gas compared to natural gas. By understanding where natural gas storage has been safe and successful that knowledge can be applied to safely store CO2.
A second type of experience related to safe storage of CO2 is our extensive history of injecting CO2 for enhanced oil recovery (EOR). EOR has been conducted safely for over 40 years in the United States. A third type of relevant experience is the injection of acid gases, primarily CO2 and hydrogen sulfide, into saline geological structures in the Western United States and Western Canada. These projects are typically much smaller in scale than storage of CO2 from a power plant, but these storage projects have operated since 1989 without incident. Thus, there are many decades of experience with natural gas storage, naturally occurring CO2, and injection of CO2 from non-power plant industrial activities. This history indicates, that when properly done, the injection and storage of anthropogenic CO2 underground (or geologic storage) from power generation should be equally safe. In geologic storage of anthropogenic CO2, as with naturally occurring, geologically stored CO2, the CO2 would be stored in deep underground formations. Such formations include depleted oil and gas reservoirs, unmineable coal seams, and saline formations. Many of these formations have naturally stored carbon dioxide and other gases and fluids (i.e., petroleum) for millions of years. They have the potential to store hundreds of years' worth of anthropogenic CO2.
|DOE's Regional Carbon Sequestration Partnerships (RCSPs) are working to validate that CO2 storage can be safely achieved throughout the United States and portions of Canada.
In August 2010, the Interagency Task Force on CCS stated, "Commercial-scale experience is limited but encouraging; these efforts are working to demonstrate that application of the best available science and technology is central to ensuring storage integrity at each site." Finally, early commercial storage experiences, such as the Sleipner Project in the North Sea (14 years of operation), and the Weyburn Project in Saskatchewan (10 years of operation) have been successful, with no evidence of safety problems. Today we have the benefit of over 40 years of cumulative experience from which we can draw conclusions regarding the risks of CO2 storage projects. Taken together, this evidence suggests that CO2 storage for large-scale projects is safe, assuming that sites are well selected, designed, operated, and appropriately.
||CO2 injection is unlikely to be safe because it is expected to migrate to the surface.
||Considerable experience with the injection of CO2 for EOR, underground storage of natural gas, and most importantly continuous monitoring at several large-scale CCS injection projects around the world indicates that CO2 injection is expected to be safe.