Fervo Energy has switched on the world’s first enhanced geothermal power plant. But what is enhanced geothermal energy? Here is an explainer.

Geothermal energy uses heat from inside the Earth to make electricity. Traditional plants tap natural hot spots close to the surface. These exist only in certain places, like Iceland or parts of California.

Enhanced geothermal goes deeper. Engineers drill several kilometres down, where rock is much hotter. They fracture the rock and pump water through it. The water heats up and returns as steam. The steam drives turbines to make power.

This opens far more sites for development. It is not limited to natural hot spots. That is why it is called “enhanced”.

Fervo’s Cape Station plant in Utah reached commercial operation on September 30. The first block took 23 months to build. It produces 33 MW of net power. The site could eventually reach 4 gigawatts.

Geothermal runs 24 hours a day, unlike solar or wind. It is carbon-free. That makes it attractive to data-centre operators hunting for steady power. Google has agreed to buy power from Cape Station.