Endurance Energy raises $54M for ocean-based geothermal power

Endurance Energy, a startup founded last year, has raised a $54 million Series A—an early-stage venture capital funding round—to develop ocean-based geothermal power. Founders Fund led the round, with participation from Ascend, Construct Capital, Felicis Ventures, First Round Capital, Point72 Ventures, Riot Ventures, and Voyager Ventures. The company has grown to 25 employees, 12 of whom previously worked at SpaceX. The company’s vice president of engineering previously worked at Helion Energy.

Founder and CEO Andrew Redd is a former SpaceX engineer. Redd, who grew up in the Pacific Northwest—a region affected by catastrophic fires in recent years—sought to build a renewable energy company. “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,” said Andrew Redd, the CEO of Endurance. He identified geothermal as the only real deployable, baseload renewable energy source, questioning why the sector currently accounts for only 0.4% of U.S. energy. For Redd, any future energy source must be non-polluting and provide baseload power—an energy source available 24/7—which he described as his non-negotiable requirement.

While land-based competitors like Fervo, Zanskar, XGS Energy, and Sage Geosystems drill thousands of feet into the crust in California or Iceland, Endurance is looking to the ocean. The company plans to target the Ring of Fire, a geologically active zone encircling the Pacific Ocean. Operating deep underwater presents challenges, including water pressure and corrosion, but Redd points to the oil and gas industry’s offshore drilling experience as a precedent. He also minimized environmental risks, noting that a potential “blowout” would simply leak hot water into the ocean, which already naturally leaks terawatts of hot water across the Earth.

The company plans to use submarine cables to transmit power. Redd estimates there is about 6 terawatts of geothermal potential that could be developed in the next five to 10 years around the Ring of Fire, which includes the U.S., Japan, and Southeast Asia. He noted that the technology could eventually support any major coastal city along the Ring of Fire. To put this in perspective, world energy usage averages about 20 terawatts across all sources at any given moment.

Why it matters

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.