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Endurance Energy says its Adélie test unit generated about 60 watt-hours of electricity for roughly 29 seconds at a hydrothermal vent near Oregon’s Axial Seamount in September 2026. The demonstration showed that the subsea geothermal concept can produce electricity, but the unit did not generate power from the well drilled for the test, and equipment failures ended the run. The company plans another test this winter; the technology’s reliability and commercial viability remain unproven.
Endurance Energy says its experimental geothermal system generated about 60 watt-hours of electricity for roughly 29 seconds at a hydrothermal vent off the Oregon coast in September. The test, conducted about a mile below the Pacific Ocean’s surface, is a technical demonstration rather than evidence of a commercially usable power source: the system did not generate electricity from the well drilled for the experiment, and its run ended after equipment problems.
The Seattle startup deployed its Adélie test unit during a three-week demonstration at Axial Seamount, an active underwater volcano about 300 miles west of Oregon. The company first drilled a relatively shallow well into a vent field, but the unit did not produce power from that well. The team then moved it to a nearby natural hydrothermal vent, where it ran on Sept. 27.
Endurance said Adélie produced about 60 watt-hours over approximately 29 seconds. For nearly nine seconds, the system generated more electricity than it consumed, sending the surplus to its battery backup. The run stopped when the battery’s overcurrent protection activated; a power cable failed soon afterward, ending the dive. The company did not report a sustained operating period or a larger output from the test.
The three-ton system uses an organic Rankine cycle, a technology also used in some land-based geothermal plants. Heat from hydrothermal fluid transfers to a working fluid that drives a turbine. A remotely operated submarine connected Adélie to the well, while a team in Seattle used an existing fiber-optic cable network to monitor temperatures and flow rates and operate the system.
A Brief Test, Not Commercial Power
The demonstration offers evidence that a geothermal turbine can generate electricity at a deep-sea vent, but its scale and duration leave major questions unanswered. About 60 watt-hours over 29 seconds is a limited test result, not proof that the system can supply continuous electricity, operate reliably for long periods, or deliver power at a competitive cost.
Those distinctions matter because Endurance is pursuing a more demanding setting than conventional land-based geothermal projects. Equipment must withstand high pressure, corrosive seawater and difficult offshore maintenance. Power also has to reach customers, potentially over long distances. Geologist Emily Pope of the Center for Climate and Energy Solutions told Canary Media that these challenges could make offshore projects difficult to justify economically.
The company has raised $63 million and is working with Tonga on a proposed two-megawatt project intended to reduce the island nation’s reliance on imported diesel. That is a plan, not a result of the Oregon test. The next technical milestones—longer operation and higher output—will help clarify whether the idea can progress beyond a demonstration.
Why Endurance Went Offshore
Endurance was founded in January 2025 by Andrew Redd, a former SpaceX engineer, to develop geothermal power in volcanically active regions where tectonic plates spread apart. The company’s approach differs from the more common focus on accessing heat beneath land. Redd told Canary Media that Endurance is designing equipment from scratch for the pressures and corrosive conditions of the deep ocean, including extensive use of titanium.
Offshore geothermal has had earlier research efforts, though not at the scale Endurance says it is pursuing. Canary Media reported that Chinese scientists produced a few watts of sustained power from a hydrothermal vent in 2016. A government-backed project in southwest Iceland drilled a geothermal well near the Mid-Atlantic Ridge, but corrosive seawater created engineering difficulties.
Axial Seamount is a monitored research area associated with the University of Washington and the National Science Foundation’s Ocean Observatories Initiative. Endurance said the existing research infrastructure and environmental monitoring made the site suitable for its demonstration. The test therefore took place in a location with established scientific observation, though that does not establish the technology’s performance at other sites.
“We follow the adage ‘make it exist, then make it good.’ Adélie made it exist, and now we know it’s possible.”
— Andrew Redd, Endurance Energy founder and CEO
Reliability and Costs Remain Open
The test does not show how long Adélie could operate under normal conditions, how much electricity a larger system could generate, or whether it can repeatedly withstand deep-sea pressure and corrosion. The company has not established the cost of producing and delivering offshore geothermal electricity, or whether that cost could compete with alternatives.
It is also unclear how the system would perform beyond the specific vent site at Axial Seamount. The drilled well did not produce electricity during this demonstration, so the reported generation came from a nearby natural vent. Endurance’s proposed Tonga project and its commercial-scale plans remain future developments; the Oregon test alone does not confirm that either can be built or operated as intended.
Winter Test Targets Longer Runs
Redd told Canary Media that Endurance is redesigning parts of Adélie after reviewing the demonstration. The company plans to deploy a refurbished unit this winter, with the goal of producing more power for longer than the September run. The timing and performance results of that next test will offer a clearer measure of progress, but no outcome has yet been reported.
In parallel, Endurance is developing a larger system that Redd said might begin generating electricity in 2027. The company has also described a proposed two-megawatt project with Tonga. Those milestones depend on further engineering and testing; the source report does not provide a confirmed deployment schedule or commercial terms for the Tonga plan.
Key Questions
How much electricity did the Adélie test generate?
Endurance said the system generated about 60 watt-hours over roughly 29 seconds at a natural hydrothermal vent on Sept. 27. For nearly nine seconds, output exceeded the system’s own power use.
Did the system generate power from the drilled well?
No. According to the report, Adélie did not produce power from the well drilled for the test. The team moved it to a nearby natural vent, where it generated the reported electricity.
Why did the test end?
The run ended after the battery’s overcurrent protection activated. A power cable failed soon afterward, and the dive was called off.
Is Endurance already supplying electricity to customers?
The report describes a short demonstration, not a commercial power supply. Endurance has proposed a two-megawatt project with Tonga, but the source does not report that the project has been built or is generating electricity.
What is Endurance planning next?
The company plans to deploy a refurbished Adélie unit this winter, aiming for greater output and a longer run. It is also developing a larger system that CEO Andrew Redd said might begin generating electricity in 2027.
Source: rss
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