The promise of coupling geologic CO2 storage with sedimentary basin geothermal power generation

Achieving ambitious greenhouse gas mitigation targets will require technological advances and cost reductions in dispatchable carbon-free power generation sources that can provide load following flexibility to integrate high penetrations of variable wind and solar power. Several other sectors may be difficult to decarbonize and a net-zero or net-negative carbon economy may require the deployment of geologic carbon dioxide (CO2) storage. Utilizing CO2 as a working fluid for geothermal energy production and energy storage can achieve both goals: isolating CO2 from the atmosphere and providing valuable power system services to enable high penetrations of variable carbon-free electricity production. The use of CO2 as a working fluid facilitates access to low-grade heat in sedimentary basins, which are widely available and could allow for strategic citing near CO2 sources or where power system flexibility is needed. In this perspective piece, we summarize the state of knowledge for sedimentary basin CO2-geothermal, sometimes referred to as CO2 plume geothermal, and explore how it could support decarbonization of the energy sector. We also present the potential for using geologically stored CO2 for bulk energy storage which could provide valuable time-shifting and other services to the power grid. We explore the promise and challenges of these technologies, identify key research gaps, and offer a critical appraisal of the role that policy for a technology at the intersection of renewable energy, energy storage, and geologic CO2 storage may play in achieving broad deployment.