CO2 removal by silicate weathering and carbon mineralization

The removal of CO2 from the atmosphere and its secure storage in reservoirs such as carbonate minerals is likely a necessary part of addressing the increasingly urgent climate crisis. On geologic timescales, natural mineral weathering reactions have acted to control CO2 concentrations in the atmosphere; the dissolution of atmospheric CO2 in rain drives mineral weathering. Dissolved carbon is then transported to the oceans, where it can precipitate as carbonate minerals, like calcite and aragonite, that store carbon in solid form over geologic timescales. If natural weathering rates can be sufficiently accelerated, this process can be used to help offset the CO2 emissions from human activities. The approach of storing CO2 in carbonate minerals is referred to as carbon mineralization. The Environmental Geochemistry Group investigates methods to accelerate carbon mineralization in Mg-rich rocks and industrial waste materials. The fine-grained rock waste that is generated during mining operations for materials such as nickel, chromite, and diamond, are particularly well-suited to capture CO2. In our group, we investigate the mechanisms that control these mineral weathering reactions to help better design CO2 capture and storage strategies. We examine means of accelerating CO2 removal, the security of storage (e.g., carbonate mineral precipitation pathways and solubility), isotopic tracers of CO2-storing reactions (Si, Mg, Ca, C, O), and the fate of potentially hazardous or potentially valuable metals during CO2-storing reactions.

Carbon mineralization
Carbon mineralization: a Mg-carbonate mineral, nesquehonite (in blue), replaces a brucite [Mg(OH)2] (in red) and stores CO2. Image has been false-coloured.