Houston-based Fervo Energy, a provider of geothermal power, has signed up one of the country’s largest utilities as a new customer.

Under two 15-year deals, Southern California Edison has agreed to buy a total of 320 megawatts of geothermal power from Fervo. Financial terms weren’t disclosed. The power will be enough to deliver electricity to the equivalent of 350,000 homes.

Southern California Edison, based in Rosemead, California, serves about 15 million people throughout a 50,000-square-mile area in California.

The utility will purchase the power from Fervo’s 400-megawatt Cape Station plant, which is under construction in southwest Utah. The plant’s first phase, providing 70 megawatts of power, is expected to be online by 2026.

“This announcement is another milestone in California’s commitment to clean zero-carbon electricity,” David Hochschild, chair of the California Energy Commission, says in a news release.

“Enhanced geothermal systems complement our abundant wind and solar resources by providing critical base load when those sources are limited,” he adds. “This is key to ensuring reliability as we continue to transition away from fossil fuels.”

In June, Fervo announced it would supply 115 megawatts of geothermal power for Google’s two data centers in Nevada. Two years ago, Fervo signed a deal with energy aggregators in California to supply 53 megawatts of geothermal power from Cape Station.

“As electrification increases and climate change burdens already fragile infrastructure, geothermal will only play a bigger role in U.S. power markets,” says Dawn Owens, Fervo's head of development and commercial markets.