Endurance Energy Tests Subsea Geothermal Power Generation Off Oregon Coast
The startup successfully generated electricity for nearly 30 seconds using heat from an underwater volcano during a recent deep-sea demonstration.
Seattle-based startup Endurance Energy has completed a three-week demonstration of its Adélie test unit, which generated electricity from an underwater volcano off the coast of Oregon. During the September trial, the system produced power for approximately 29 seconds using heat from a hydrothermal vent. The company views the event as a milestone for the development of offshore geothermal energy technology.
The demonstration took place at the Axial Seamount, an active submarine volcano located about 483 kilometers west of Oregon along the Juan de Fuca Ridge. Using a modified geotechnical drill, the team accessed hot, mineral-rich seawater from a vent field. A submarine robot then connected the 3-ton Adélie unit to the well. The system utilizes an organic Rankine cycle to transfer heat and spin a turbine.
During the test, the unit generated about 60 watt-hours of electricity. For nearly 9 seconds, the system produced more power than it consumed, with the surplus charging an onboard battery. The operation concluded when the battery’s overcurrent protection activated, followed by a power cable failure. Endurance Energy CEO Andrew Redd stated that the company is now rearchitecting core components to improve performance and duration for a planned winter deployment.
Endurance Energy, founded in January 2025 by former SpaceX engineer Andrew Redd, has raised $63 million to scale its technology. The company is also working with the Kingdom of Tonga on a proposed 2-megawatt project intended to reduce the nation's dependence on imported diesel. While some experts question the economic viability of offshore geothermal due to harsh ocean conditions and high costs, the company aims to design systems capable of withstanding deep-sea pressures.
The startup plans to deploy a refurbished version of the Adélie unit this winter. Looking ahead, Endurance Energy is developing a larger commercial-scale system that could potentially begin generating electricity in 2027.
