科研之友
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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. The presence of acid gases such as SO, (and NOR) will likely have a negative effect particularly in the near-well region due to their tendency to accumulate in acidic forms in the water (and mineral phases) around the injection well. Other impurities that may be present in the CO2 stream, such as O-2 and H2S, may or may not have a negative effect, depending on aquifer's mineral composition. The severity of these effects should be evaluated through appropriate modelling of the impure-CO2/water/rock system. In extreme cases this may impose more severe limitations than those imposed by transportation systems on the type and amount of certain impurities present in the CO2 stream. In general, further development of the work performed to date will continue to yield valuable results dealing with impure-CO2/ aquifer interactions. Future research will benefit from closer integration between the various research communities to better define the myriad chemical environments which may develop due to the injection of impure CO2 streams. Exploration of the post-injection interactions in the vicinity of injection wells is one avenue which should be explored more vigorously.
- 出版日期2015-9
