Water-CO2-rock interaction during carbon sequestration

Carbon capture and storage looks to be the most promising option to stem the rise in atmospheric CO2 concentration and its consequences including global warming. Consideration of the various options available suggests that geological storage will probably dominate future carbon-storage efforts. The safest geological storage host is the formation of carbonate minerals. Carbonate mineral formation is favoured by the presence of reactive divalent-metal silicate minerals, in particular basalts and ultra-mafic rocks. In the absence of such rocks the most stable form of injected CO2 is likely to be via solubility trapping, which involves its dissolution into formation waters. The quantity of CO2 that can be stored via solubility depends on the composition of the formation waters and is greatly enhanced by increasing the pH and the formation of aqueous carbonate complexes. © 2010 the European Mineralogical Union and the Mineralogical Society of Great Britain&Ireland.