In its largest-ever purchase agreement, Houston-based geothermal company Fervo Energy will supply 396 megawatts of power to tech powerhouse Google.

The deal includes an option for Google to expand capacity by about 600 megawatts, for a total of 1 gigawatt, by June 2030, according to a news release from Fervo. Financial terms weren’t disclosed.

Google will purchase carbon-free energy from Fervo for a potential data center in Utah, where Fervo is building its more than $2 billion Cape Station geothermal project.

Fervo applies oil-and-gas fracking technology to create geothermal reservoirs and generate electricity.

The first phase of Cape Station is expected to begin delivering geothermal power by late 2026, reaching about 100 megawatts of capacity by early 2027. The second phase, set for completion in 2028, will add 400 megawatts of capacity.

Fervo co-founder and CEO Tim Latimer said in a release that the Google agreement supports enhanced geothermal systems as a key power source for “the next generation of computing infrastructure.”

“The next chapter of advanced power generation technology is being written in Utah,” said Lucia Tian, director of advanced energy technologies at Google.

The Fervo-Google agreement builds on an existing partnership. Fervo’s Project Red pilot development in Nevada, which came online in 2023, supplies power to the local grid. Users of the grid power include Google’s data centers in Nevada.

Fervo subsequently signed a 115-megawatt purchase agreement with Google and NV Energy. The deal enabled Google to bring more geothermal energy to the Nevada grid while insulating everyday customers from the project’s costs.

The latest Google deal is part of the ongoing expansion of Cape Station beyond its initial 100-megawatt phase. Fervo says Cape Station will be the world’s largest enhanced geothermal facility.

The Google agreement comes during a milestone year for Fervo, which was founded in 2017. In May, Fervo’s IPO raised $2.2 billion. The company, whose early investors include Bill Gates, is now valued at $5.65 billion.