A geothermal energy demo device built by Seattle startup Endurance being tested in the Mariana Islands. (Endurance photo via LinkedIn)
Endurance Energy, a Seattle-based startup developing technology to extract energy from the heat beneath the ocean floor, has raised $54 million.
The team — led by former SpaceX engineer Andrew Reed — is racing to meet surging demand for clean power, with plans to deliver electricity to the grid within two years.
“Our SpaceX heritage enables a pace of development that is unprecedented for new energy projects,” the company said Thursday on LinkedIn.
Redd launched Endurance in 2024. Over the past year, the startup has completed four prototype deployments to deep-sea volcanoes up to nearly 1,000 feet below the surface, where volcanic systems heat water to 728 degrees Fahrenheit.
Geothermal companies produce energy by drilling wells into underground reservoirs of hot water or steam, bringing that fluid to the surface and using it to spin turbines that generate electricity, then reinjecting it back into the reservoir.
Endurance is unique in its pursuit of undersea geothermal sources and aims to produce power on the gigawatt scale. For comparison: Washington’s Grand Coulee Dam has a generating capacity of 6.8 gigawatts and it’s the largest power station of any kind in the U.S.
Hitting gigawatt generation will take time. Endurance is on track this fall to deploy its 100 kilowatt generator dubbed “Adelie” to the underwater volcanic range called Juan de Fuca ridge, located off the coast of Washington and Oregon. Adelie is the company’s first complete system, which is capable of drilling under the ocean, generating power from that drilling and handling the energy transfer.
Geothermal power has become a hot ticket in the clean energy sector. With Google as a key investor, Fervo Energy raised $462 million in December, bringing its total to more than $1.5 billion. Sage Geosystems closed a round worth over $97 million in January.
Geothermal sources currently account for only 0.4% of U.S. power generation — but that share is expected to grow given the technology’s potential to provide around-the-clock, carbon-free electricity.
Redd, a Pacific Northwest native, is building his company on the north shore of Seattle’s Lake Union. He praised the location for its ample moorage and allowing the team to load seafloor drills and power generators directly onto seagoing vessels.
“Subsea geothermal and Seattle is a match made in heaven,” Redd said on LinkedIn. “The opportunity to work on renewable energy, with a group of people this talented, right back home, is a dream come true!”
The startup has 25 employees, according to TechCrunch, 12 of whom previously worked at SpaceX.
The Series A round was led by Founders Fund with new investors Felicis, Voyager Ventures, Riot Ventures and Construct Capital. Previous backers Point72 Ventures, First Round Capital and Ascend also participated.
