This geothermal startup produced a tiny bit of power from the seafloor

Endurance Energy, a Seattle-based startup founded in January 2025 by former SpaceX engineer Andrew Redd, deployed its test unit Adélie about a mile below the Pacific Ocean off Oregon in September. The three-week demonstration aimed to prove the feasibility of generating electricity from underwater volcanic heat, a concept the company describes as a potential clean, always-on energy source. The project targeted the Axial Seamount, an active submarine volcano along the Juan de Fuca Ridge, chosen for its volcanic activity and existing research infrastructure.

The Adélie unit, weighing 3 tons, was lowered to the seafloor where a submarine robot connected it to a shallow well drilled into a hydrothermal vent. The system used an organic Rankine cycle to transfer heat from mineral-rich seawater to spin a turbine and generate power. On Sept. 27, the turbine produced approximately 60 watt-hours over 29 seconds, briefly generating more power than it consumed before a power cable failure ended the test.

Endurance Energy reported that Adélie operated remotely from Seattle using real-time data transmitted via an existing fiber-optic cable network, marking the first end-to-end demonstration of subsea geothermal power generation. The company plans to refurbish Adélie and redeploy it this winter to achieve higher power output and longer runtime, while also developing a larger commercial-scale system aimed at commercial operation by 2027.

Geologist Emily Pope of the Center for Climate and Energy Solutions noted that while offshore geothermal is scientifically intriguing, economic viability remains uncertain due to harsh ocean conditions and high costs. Previous attempts, such as a 2016 Chinese project producing a few watts and an Icelandic effort hindered by corrosion, underscore the technical challenges. Endurance aims to differentiate itself by designing corrosion-resistant technology from scratch, including extensive use of titanium.