Geothermal power generation potential in the United States by 2050

Abstract

Geothermal energy provides a dispatchable source of carbon-free electricity that can balance the output of variable resources. However, geothermal provides just 3.7 gigawatts (GW _e ) ( ${\lt}$ 1%) of electricity in the United States today, mostly from hydrothermal resources that are geographically constrained. Enhanced geothermal systems (EGS), which extract heat from deep rock, could be applicable in more locations. However, baseline levels and potential trends in EGS costs have been insufficiently characterized by previous studies. Here, we assess geothermal penetration potential by using as baseline the latest available data on drilling costs from three costing models to create updated estimates of costs and performance. We input those estimates along with various scenarios of cost trends, emissions policies, and electricity demand into the regional energy deployment system (ReEDS) capacity expansion model to simulate electricity generation in the United States through 2050. The scarcity of hydrothermal resources limits deployments to no more than 18 GW _e across our scenarios. EGS is more costly than hydrothermal for now, but it has greater potential to scale nationwide. Thus, future deployments of EGS depend strongly on projected cost reductions and emissions policies. In scenarios with moderate ( ${\lt}$ 50%) reductions in costs by 2050, very little EGS is likely to be built, since wind and solar with storage provide lower-cost electricity. However, over 70% cost reductions from our updated baseline would make geothermal the least-cost carbon-free dispatchable resource. Under those cost trends, we project that 3 GW _e of EGS would be built by 2050 under existing policies, 11 GW _e with a 95% decarbonization policy, and 152 GW _e if full decarbonization of electricity is mandated. Most geothermal would likely first be built in western states with the steepest subsurface temperature gradients, although mandates for full decarbonization could drive it to be deployed in other states.

Keywords

• renewable energy
• geothermal
• EGS
• capacity expansion model
• decarbonization