Sensitivity of the CO2 storage capacity of underground geological structures to the presence of SO2 and other impurities

For volumetric trapping, the greatest positive impact of SO2 occurs at relatively low pressures (74-100 bar) and temperatures (313-325 K). These are typical for shallow (<1 km) aquifers or deeper depleted hydrocarbon reservoirs during the injection stage. For solubility trapping, the STC enhancement by SO2 increases with pressure and is relatively insensitive to temperature, implying that the greatest positive effect would be achieved for deep saline aquifers. These findings suggest that the positive effects of SO2 on the CO2 storage capacity could be of practical significance for CCS projects. The positive storage effects would have to be evaluated relative to possible negative effects due to induced geochemical reactions, corrosion of well casings, and health risks associated with potential leakage from transport or injection facilities or from the storage reservoir.