First Subsea Geothermal Power Plant Test Succeeds

Endurance Energy completed the first test of a subsea geothermal power plant at Axial Seamount in the northeast Pacific this September, at 5,000 feet depth. The three-week trial of a 3-ton prototype generated less than 10 seconds of net-positive electricity, establishing technical feasibility for extracting geothermal energy from the seafloor.

The startup targets Pacific island nations and other regions seeking renewable alternatives to costly imported fossil fuels. Subsea operations offer advantages: abundant cold seawater enables efficient cooling, and ocean pressure allows for compact turbine systems. However, deep-sea drilling presents substantial technical and economic challenges compared to land-based geothermal plants. Endurance Energy must demonstrate reliable underwater operations and achieve cost-competitiveness before commercialization.

Energy experts view the concept as technically sound but likely significantly more expensive than terrestrial alternatives, creating uncertainty about whether the economics will work for target markets.