Subsurface geochemical fate and effects of impurities contained in a CO2 stream injected into a deep saline aquifer: What is known

摘要

Geological storage of anthropogenic CO2 captured from large emitters has been identified and demonstrated on a pilot and commercial scale as a viable means for reducing atmospheric CO2 emissions from fossil-fuel based power generation and other industrial processes such as cement and steel making. In particular, CO2 storage in deep saline aquifers has been identified as having the greatest capacity and widest global distribution. Although the captured stream will be "overwhelmingly CO2", any number of source and/or process associated impurities may be co-injected, with the potential of additional impurities initially present in the aquifer being incorporated in the plume of stored CO2 post-injection. Impurities may make the injected phase more reactive than pure CO2 and will also change the physical properties of the injected CO2 stream. This paper documents the progress since the IPCC Special Report on CCS in understanding the fate and geochemical effects of these impurities when co-injected in an impure CO2 stream into deep saline aquifers. The presence of inert or non-condensable impurities in the injected CO2 stream, such as Ar, N-2 and CH4, will have no or negligible geochemical effects in the subsurface, notwithstanding a reduction in CO2 storage capacity.