Houston-based Fervo Energy, a pioneer in developing enhanced geothermal systems (EGS) that employ hydraulic fracturing to produce geothermal energy, has signed two power purchase agreements (PPAs) with Southern California Edison (SCE) to provide 320 MW of electricity.
The 15-year agreements represent the world’s largest geothermal PPAs to date, Fervo announced in a 25 June press announcement.
SCE will purchase the power from Fervo Energy’s 400-MW Cape Station project, currently under construction in Beaver County, Utah. The first 70-MW phase of the project is expected to be operational by 2026 and reach capacity by 2028.
With the SCE deal, Fervo has now contracted for 373 MW of Cape Stations’ eventual 400- MW nameplate capacity.
The Cape Station project calls for drilling up to 29 wells, of which 21 will be horizontal EGS wells that rely on hydraulic fracturing to boost flow rates of hot water, and 8 vertical wells for observational purposes.
Target depths for the horizontal injection and production geothermal wells are anticipated at about 8,000 ft with laterals that will extend for about 5,000 ft.
Fervo recently chose Mitsubishi subsidiary Turboden to engineer and procure the first phase of Cape Station’s three generators, which will be equipped with six of Turboden’s closed-loop turbines.
Adding Critical Baseload
Commenting on Fervo’s PPA announcement, California Energy Commission Chair David Hochschild said geothermal “is key to ensuring (grid) reliability” because it can provide “critical baseload” when wind and solar resources are limited.
The California Public Utilities Commission issued a mid-term reliability (MTR) mandate in 2021 requiring utilities to procure 1,000 MW of non-weather-dependent, non-battery, zero-emission energy to boost the reliability of the state’s electric grid.
This decision catalyzed demand for geothermal, despite its higher cost—a fact that had given wind and solar the advantage until weather and battery issues were taken into consideration.
The Golden State is the largest geothermal producer in the US given the strength of its volcanic activity, though ironically geothermal energy comprises only 22% of California’s renewable energy mix, according to California Audubon.
California is home to the largest geothermal field in the world: The Geysers, located 72 miles north of San Francisco, is capable of generating 1,800 MW of electricity, according to the US Department of the Interior’s Bureau of Land Management (BLM).
The Geysers field lies at the southwest margin of the Clear Lake volcanic field, according to the US Geological Survey, which also singles out the Salton Sea resource in Imperial Valley (which BLM says could deliver 2,200 MW), and the Mammoth Geothermal Complex in the Long Valley Caldera. All currently feed geothermal energy to the grid.
Cutting Geothermal Costs
Fervo is betting that its approach using bread and butter oil and gas technologies, including fracturing, will bring down costs and give zero-carbon geothermal an ever-growing share of the renewable energy mix.
At a February 2024 workshop for geothermal reservoir engineers at Stanford University, Fervo presented results of its drilling technology that demonstrated faster drilling times and an overall reduction in costs at Cape Station.
