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.