Enhanced Geothermal Systems for Reliable Decarbonization of the California Energy Grid

Abstract

In California, the progress towards net-zero carbon economy has been highly dependent on the rapid growth of solar and wind electricity, as well as electrification of transportation and heating. However, the increasing reliance on weather-dependent renewables can raise grid reliability concerns. Among the diverse array of renewables, enhanced geothermal systems (EGS) present a promising solution for clean firm energy that could alleviate such challenges. This study evaluated the techno-economic impacts of EGS integration into California’s energy system by using a gas-electric capacity expansion model. This model optimizes electricity and heating investments while meeting progressively stringent emissions targets to ensure a cost-effective transition to a net-zero economy by 2045. We analyzed multiple EGS deployment scenarios, varying in drilling depth, seismic exclusion zones, and dispatch flexibility. Results indicated up to 82 GW of EGS capacity installed by 2045, reducing total system capacity needs by 40% and lowering system costs by 8.6% compared to cases without EGS. Furthermore, flexible dispatch reduced system costs by 12.3% in aggregate. EGS also significantly decreased reliance on power-to-gas systems, supporting heating electrification and reducing power-to-gas capacity needs by 50%. These findings highlight EGS as a key enabler of California’s clean energy transition across both the electricity and gas sectors.