The agreement of energy sale signed Fervo Energy and the utility Southern California Edison puts into play a power of 320 MW through two geothermal plants "enhanced"
The World’s Largest Geothermal PPA Agreement
Fifteen years of renewable energy supply and “carbon-free” guaranteed 24 hours a day, 7 days a day. This is the subject of the close agreement between Fervo Energy, a company active in improved geothermal systems, and the American utility Southern California Edison, signatories of the world’s largest geothermic PPA. The record size belongs to the power put at stake – 320 MW – in the purchase contract. More precisely, in the two contracts from now on, the production plant will have two implementation phases, in 2026 and 2028, each of which will correspond to a Power Purchase Agreement.
Fervo Energy’s ESG geothermal technology
The energy will come from the Cape Station project that Fervo Energy is building in southwestern Utah. The company plans to build here a large 400 MW geothermal system based on ESG technology (Enhanced geothermal systems). What is this about? ESG, also called enhanced or enhanced geothermal, generates electricity by exploiting underground hot rocks that artificially increase their permeability. This increase occurs through a variety of stimulation methods, including thermal stresses, chemical treatments, or “hydraulic billing.”
In most cases, ESG geothermal plants utilize a vertical injection well of pressurized water to trigger cutting events between rocks. The aim is to improve permeability and create new splits.
Fervo Energy stands out in the field with horizontal drilling techniques that create long horizontal channels through the rock. In the first tests, the company achieved side lengths of 990 meters and a temperature of 191 °C with a strictly controlled flow. The company has also implemented an induced seismicity mitigation protocol, one of the main problems of enhanced geothermal energy due to the high pressures involved.
The Advanced Geothermal Project of Cape Station
In this context, the Cape Station project in Utah – whose exploration drilling campaign began only in 2023 – was immediately noticed. And not only for the planned power, 400 MW. If the operation yields the desired results, the initiative could be replicated within the state, for which scientists estimate a potential of 10 GW of high-quality geothermal reserves.
But the new geothermal PPA is, above all, a step forward in California’s energy transition. In 2021, the California Public Utilities Commission issued a medium-term reliability mandate (MTR) requiring utilities to obtain 1 GW of non-weather, non-battery, and zero-emission power capacity to increase the reliability of the state’s power grid. This decision has inevitably catalysed the demand for geothermal energy.
“This announcement is another milestone in California’s commitment to clean, zero-carbon electricity,” said California Energy Commission President David Hochschild. “Enhanced geothermal systems complement our abundant wind and solar resources by providing a critical base load when such sources are limited. This is crucial to ensuring reliability as we continue the transition from fossil fuels.”
