Carbon capture and storage (CCS) is an approach to mitigate global warming by capturing carbon dioxide (CO 2 ) from large point sources such as fossil fuel power plants and storing it instead of releasing it into the atmosphere. Technology for large scale capture of CO 2 is already commercially available and fairly well developed. Although CO 2 has been injected into geological formations for various purposes, the long term storage of CO 2 is a relatively untried concept and as yet (2007) no large scale power plant operates with a full carbon capture and storage system.

CCS applied to a modern conventional power plant could reduce CO 2 emissions to the atmosphere by approximately 80-90% compared to a plant without CCS [IPCC, 2005] IPCC special report on Carbon Dioxide Capture and Storage. Prepared by working group III of the . Metz, B., O.Davidson, H. C. de Coninck, M. Loos, and L.A. Meyer (eds.). Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 442 pp. Available in full at blank">www.ipcc.ch . Capturing and compressing CO 2 requires much energy and would increase the fuel needs of a plant with CCS by about 11-40% . These and other system costs are estimated to increase the cost of energy from a new power plant with CCS by 21-91% . These estimates apply to purpose-built plants near a storage location: applying the technology to preexisting plants or plants far from a storage location will be more expensive.

Storage of the CO 2 is envisaged either in deep geological formations, in deep ocean masses, or in the form of mineral carbonates. In the case of deep ocean storage, there is a risk of greatly increasing the problem of ocean acidification, a problem that also stems from the excess of carbon dioxide already in the atmosphere and oceans. Geological formations are currently considered the most promising sequestration sites, and these are estimated to have a storage capacity of at least 2000 Gt CO 2 (currently, 30 Gt per year of CO 2 is emitted due to human activities ). _IPCC estimates that the economic potential of CCS could be between 10% and 55% of the total carbon mitigation effort until year 2100 (Section 8.3.3 of IPCC report ).