Effects of Bulk Energy Storage in Sedimentary Basin Geothermal Resources on Transmission Constrained Electricity Systems

Abstract

Sedimentary basin geothermal resources and carbon dioxide (CO2) can be used for bulk energy storage (CO2-BES), which could reduce the capacity, and thus cost, of high voltage direct current (HVDC) transmission infrastructure needed to connect high quality wind resources to distant load centers. In this study, we simulated CO2-BES operation in the Minnelusa Aquifer in eastern Wyoming and used those results in an optimization model to determine the impact that CO2-BES could have on the revenue of a wind farm that sells electricity to the California Independent System Operator (CAISO) market under varying HVDC transmission capacity scenarios. We found that the CO2-BES facility can dispatch more electricity than was previously stored because of the geothermal energy input. While CO2-BES performance degrades because of geothermal resource depletion, our results suggest that a CO2-BES facility could increase revenue from electricity sales throughout its lifetime by (1) increasing the utilization of HVDC transmission capacity, and (2) enabling arbitrage of the electricity prices in the CAISO market. In some cases, adding CO2-BES can provide more revenue with less HVDC transmission capacity.