Build Here: How Targeted State Investment in Geothermal Can Fill California’s Clean Firm Gap

The report argues that next-generation geothermal, specifically enhanced geothermal systems (EGS), can provide the 'clean firm' power California needs to reach its 2045 goals affordably. Modeling shows that EGS could reduce annual electricity supply costs by $10-44 billion and decrease the required pace of solar installation from 10 GW/year to 3 GW/year. While projects are currently being developed in other western states, the authors argue that in-state development would further save $3.5-5.5 billion annually and reduce interregional transmission needs by 28-53%. To overcome the 'missing middle' of financing for high-risk exploration wells, the report recommends California establish a public subsurface mapping and testbed program similar to the DOE's FORGE project in Utah.

• The deployment of commercially mature enhanced geothermal systems (EGS) with average costs between $2,700/kW and $7,700/kW could lower California's annual electricity supply costs in 2045 by $10-44 billion, representing a reduction of 23-52% compared to scenarios where such technologies are unavailable.
• Developing EGS within California provides additional annual cost savings of $3.5-5.5 billion over scenarios where the power is sourced from out-of-state, primarily by utilizing higher-quality local resources and avoiding interregional transmission expansion.
• Large-scale EGS deployment would significantly reduce the necessary buildout of other clean energy infrastructure; for instance, 30 GW of EGS would allow California to maintain solar installation at 3 GW/year instead of increasing it to nearly 10 GW/year.
• In-state EGS availability reduces the need for interregional transmission expansion by 28-53% compared to a baseline without geothermal, whereas relying on out-of-state EGS would increase transmission needs by 35-62%.
• The availability of EGS, particularly when deployed in-state, reduces the marginal cost of greenhouse gas abatement in the electricity system by 50-100%.
• A significant barrier to development is the 'missing middle' of financing for exploration wells, which cost between $5 million and $20 million and carry high subsurface uncertainty that traditional infrastructure investors avoid.
• The report recommends California fund a subsurface exploration and mapping program, modeled after the U.S. Department of Energy's FORGE project in Utah, to reduce technical uncertainty and attract private capital.

APA

Ricks, W., & Garth, A. (2026). Build Here: How Targeted State Investment in Geothermal Can Fill California’s Clean Firm Gap. Clean Air Task Force. https://cdn.catf.us/wp-content/uploads/2026/05/20122941/California-Testbed-Report.pdf

Chicago

Ricks, Wilson, and Ann Garth. Build Here: How Targeted State Investment in Geothermal Can Fill California’s Clean Firm Gap. Clean Air Task Force, 2026. https://cdn.catf.us/wp-content/uploads/2026/05/20122941/California-Testbed-Report.pdf.

Wikipedia

{{cite report |last1=Ricks |first1=Wilson |last2=Garth |first2=Ann |title=Build Here: How Targeted State Investment in Geothermal Can Fill California’s Clean Firm Gap |publisher=Clean Air Task Force |date=May 2026 |url=https://cdn.catf.us/wp-content/uploads/2026/05/20122941/California-Testbed-Report.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{ricks2026build, author = {Ricks, Wilson and Garth, Ann}, title = {{Build Here: How Targeted State Investment in Geothermal Can Fill California’s Clean Firm Gap}}, institution = {Clean Air Task Force}, year = {2026}, month = may, url = {https://cdn.catf.us/wp-content/uploads/2026/05/20122941/California-Testbed-Report.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }