Endurance Energy Tests Subsea Geothermal Power Plant

The Adélie system generated net-positive electricity during a recent trial at the Axial Seamount.

Updated on Oct. 28, 2026 in Energy

Isometric editorial illustration of a modular geothermal power unit anchored on the dark seafloor near volcanic vents. — Endurance Energy successfully tested its Adélie subsea geothermal system at the Axial Seamount, proving that seafloor vents can generate net-positive electricity. AI Illustration. Upload story photo >

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Endurance Energy successfully tested its Adélie subsea geothermal power plant at the Axial Seamount, 300 miles off the Oregon coast. The system achieved net-positive electricity generation during the trial before a power cable failure occurred.

Why it matters

The company aimed to prove that the Adélie system could successfully generate more power than it consumes using natural seafloor hydrothermal vents. This marks a critical step toward proving the feasibility of subsea geothermal energy harvesting.

The Adélie plant recorded a median output of 2 kilowatts of net power over an 8.7-second period using a 52-foot geothermal well. The system, which has an installed capacity of 100 kilowatts, relied on a natural hydrothermal vent for fluid flow.

The players

Endurance Energy

This startup is a developer of subsea geothermal energy technology founded in early 2025.

The details

The research team drilled two holes near a hydrothermal vent to tap into the thermal energy of the seafloor. The demonstration ended after a power cable failure interrupted the flow of electricity from the unit.

Endurance Energy was founded in January 2025.
Test results were officially announced in October 2026.
A refurbished version called Gentoo is scheduled for testing in winter 2026-27.
Commercial power generation is targeted for 2027 in the Kingdom of Tonga.

The Big Picture

The success at the Axial Seamount significantly extends the power output milestones established by the 2016 Southwest Indian Ridge power research project. This test marks a shift from laboratory-scale experiments toward functional, seafloor-deployed energy generation.

Successful subsea geothermal harvesting could eventually provide a constant, carbon-free energy source for remote island nations and deep-sea infrastructure. This technology may lower costs for powering future ocean-based monitoring equipment or underwater research stations.

The takeaway

Subsea geothermal energy represents a complex engineering challenge that requires reliable hardware to survive extreme underwater conditions. The successful brief power surge provides foundational data for future, longer-duration deployments of the Adélie and Gentoo systems.