(454a) Carbon Dioxide Utilization in Geothermal Power Generation and Geologic Energy Storage

Flexible renewable power systems and large-scale energy storage are needed to ensure power grid reliability, reduce carbon dioxide (CO2) emissions to the atmosphere, and increase energy security. The increased installed capacity of wind and solar energy in many parts of the United States is underutilized due to the challenges of matching supply and demand with inflexible baseload power plants (e.g., nuclear, coal). These baseload plants have high capital costs, have limited flexibility in their power output, and require high capacity factors for economic viability. Diurnal misalignments between power supply and demand are addressed either by curtailing intermittent renewables or using highly flexible, but inefficient, natural gas peaking plants. Existing bulk energy storage facilities – such as batteries and pumped hydro – can partially mitigate these supply problems, but they have high capital costs, limited storage capacity, and cannot address seasonal supply/demand mismatches. Overall, existing energy storage technologies are not sufficiently developed and deployed to eliminate power curtailments.

CO2 Plume Geothermal (CPG) technology, together with multifluid Earth Battery geologic energy storage, a variation of CPG, address these challenges, providing baseload or dispatchable, renewable energy systems that can be deployed over far greater geographic extents than legacy geothermal and geologic energy storage approaches. Both technologies make use of CO2 to store and carry energy through geologic formations to power conversion systems at the surface, either harnessing geothermal heat to be used in power generation or storing energy from other sources in the subsurface. These technologies are the result of an ongoing research and commercialization effort amongst the University of Minnesota, Lawrence Livermore National Laboratory, Ohio State University, ETH in Zurich, and TerraCOH Inc.

By using existing well infrastructure and by taking advantage of the increased mobility of CO2 when it is used as a heat extraction fluid in saline aquifers in sedimentary basins, CPG decreases drilling risks and increases power production efficiency over traditional geothermal generation. The net result is the potential for a massive increase in economically viable geothermal power production, together with an expansion of intermittent renewable energy systems that require grid-scale energy storage to maximize implementation.

Here, we will describe a project underway to provide the first field demonstration of a multi-stage CPG and Earth Battery deployment. We have strategically divided deployment into multiple phases, as necessary to balance research, technological demonstration and financial investment.