Carbon Dioxide Mineralization Feasibility in the United States
Geologic carbon dioxide (CO2) storage is one of many methods for stabilizing the increasing concentration of CO2 in the Earth’s atmosphere. The injection of CO2 in deep subsurface sedimentary reservoirs is the most commonly discussed method; however, the potential for CO2 leakage can create long-term stability concerns. This report discusses the feasibility of an alternative form of geologic CO2 storage: CO2 mineralization. In this method, CO2 reacts with rocks and minerals to form solid and stable carbonate rocks. New pilot projects and laboratory-based kinetics experiments have revealed that this method, both in situ and ex situ, may be a viable option for storage. In situ storage targets in-place rocks at the surface or subsurface. Ex situ storage targets industrial byproducts at the surface like mine tailings. Environmental risks include induced seismicity for in situ methods if pressure is not managed properly, as well as potential water and land use effects. However, there are fewer long-term CO2-leakage concerns for mineralization methods compared to saline storage methods and therefore potentially lower long-term monitoring costs. The costs and benefits of CO2 mineralization are compared to those of CO2 storage in saline reservoirs using estimates of pressure-limited dynamic storage capacity. This report highlights the regional potential of areas in the United States for in situ and ex situ storage, as well as their proximity to potential sources of CO2. Especially suitable targets include asbestos or other ultramafic mine tailings, in situ ultramafic rocks on the East and West Coasts, the Columbia River basalts in the Pacific Northwest, the Midcontinent Rift basalts in the midcontinent, and the basaltic Hawaiian Islands.