Subsea geothermal prototype generates net-positive electricity for seconds

Endurance Energy has completed the first demonstration of a subsea geothermal power plant near an active underwater volcano in the northeast Pacific. The prototype produced net-positive electricity for less than 10 seconds, a brief result that showed the approach can work but leaves reliability and cost effectiveness unproven.

The three-tonne, 100-kilowatt Adélie plant was tested for three weeks at Axial Seamount, around 1,524 metres below the surface. A shallow, narrow test well could not supply enough hot fluid, so the team moved the plant to a natural vent reaching about 281°C; the company says deeper wells could provide more flow. Endurance hopes the technology could help Pacific island nations reduce reliance on costly imported fossil fuels, though subsea drilling and operations may make it more expensive than land-based geothermal power.