Endurance Energy raises $54M to tap into ocean's geothermal energy

After working on rockets that find their way to outer space, it can be hard to come up with a second act. For SpaceX alumni Andrew Redd, it meant looking deep in the ocean. Redd, who grew up in the Pacific Northwest, a region affected by uncharacteristic heat waves and catastrophic fires in recent years, knew he wanted to tackle something in renewable energy.

"But the experience at a very hardcore company like SpaceX made me realize that I can't just come up with an incremental solution. It actually has to be brand new and it has to be approached from first principles," according to Redd, who was an engineer on Dragon and Starship at SpaceX. Redd left SpaceX and founded Endurance Energy, a startup that has raised a $54 million Series A to eventually harness terawatts of geothermal energy deep in the ocean.

Founders Fund led the round with participation from Point72 Ventures, Construct Capital, Felicis Ventures, First Round Capital, Riot Ventures, and Voyager Ventures. The new funding will allow the company to develop its plans for power plants at a time of surging energy demand from AI data centers, electric vehicles, and heavy industry. Since founding the company last year, Redd has grown the team to 25 employees, 12 of whom used to work at SpaceX.

The company's vice president of engineering previously worked at Helion Energy, the fusion startup. Geothermal energy isn't a new idea — humans have been using the Earth's heat for millennia, whether it be from spa-like hot springs or geothermal power plants. But Redd, drawing on his experience at SpaceX, figured there was another opportunity people were overlooking.

Here's how he distilled the problem: Any future energy source should be renewable, or at least non-polluting, in his opinion. "That's my non-negotiable," said Redd, who is CEO of Endurance. It should also be available 24/7 — or baseload power, as the industry calls it — and it should quickly deployable and able to generate tens or hundreds of gigawatts of electricity, according to Redd.

He quickly ruled out nuclear power because regulatory and construction timelines can stretch on for years. Solar and wind aren't available 24/7 without batteries, and hydropower is limited in where it can be built (plus all the good spots have been taken). That left geothermal.

"Geothermal is the only real deployable, baseload renewable," he said. "But why is it only 0.4% of U.S. energy?" There are other startups pursuing geothermal, including Fervo and Zanskar.

But those companies need to drill thousands of feet into the Earth's crust to access temperatures hot enough to drive a power plant. So far, the best opportunities for many geothermal startups has been in the Western U.S., far from large population centers. The best places to drill, where the crust is thin and magma flows close to the surface, like in Iceland or California, have long been claimed.