Seattle-based Endurance Energy announced on October 19 that its Adélie prototype successfully generated net-positive electricity using heat from an underwater volcano, ScienceAlert reported. During a test conducted at the Axial Seamount off the Oregon coast, the system produced a median surplus of approximately 2 kilowatts, peaking at 16.5 kilowatts, after accounting for the energy required to operate its own pumps and components.
Adélie prototype captures heat at Axial Seamount
The experiment took place approximately 480 kilometers (300 miles) off the coast of Oregon at the Axial Seamount, an active underwater volcano. To harness the thermal energy, engineers utilized hydrothermal vents where seawater seeps into seabed cracks, heats up via molten rock, and exits through openings in the ocean floor. While the team initially drilled a 16-meter (52-foot) well to attempt direct extraction, the resulting water flow was too restricted to power the generator.
Instead, the team connected the Adélie unit to a nearby natural vent to utilize existing water flow. During the September 27 test, the water temperature reached approximately 281°C (538°F). At a depth of 1,500 meters (5,000 feet), the high ambient pressure allows this water to remain in a liquid state well above the standard boiling point of 100°C (212°F). This thermal energy drove a turbine to approximately 26,000 revolutions per minute, facilitating the brief period of net-positive power generation.
The operation was managed remotely from Seattle, utilizing the Regional Cabled Array—an existing undersea cable network operated by the University of Washington—to maintain connectivity. The successful 8.7-second window of surplus power marks a significant technical milestone, even if the duration was momentary.
Comparing historical seafloor energy benchmarks
While Endurance Energy’s recent results show a jump in power capacity, the concept of seafloor energy conversion is not entirely new. Earlier attempts focused on much smaller scales, primarily utilizing the temperature differential between vent fluids and the surrounding cold seawater.
| Metric | 2016 Chinese Study | Endurance Energy (Adélie) |
|---|---|---|
| Primary Mechanism | Temperature differential conversion | Turbine-driven generation |
| Power Output | 2.6–3.9 watts | 2 kW median (16.5 kW peak) |
| Primary Application | Data loggers and LED lamps | Commercial grid supply potential |
Technical failures and the Gentoo upgrade path
The 8.7-second run concluded when a safety system triggered to protect the onboard battery from excessive current. When engineers attempted to restart the system, a pump power cable failed approximately 10 minutes later.
To address these reliability issues, the company is developing an upgraded 100kW test generator named Gentoo. According to Endurance founder Andrew Redd, the Gentoo unit is scheduled for deployment this winter and is designed specifically to solve the battery protection and pump cable vulnerabilities identified during the Adélie experiment. The company also plans to deploy a new drill next year capable of reaching depths of 500 meters (1,640 feet), a significant increase from the current 80-meter (260-foot) limit, which the company expects will result in higher water flow rates.
The long-term objective remains the transition from experimental prototypes to commercial geothermal power plants. Endurance Energy is currently developing its first commercial project in Tonga, a Pacific island nation that relies heavily on imported diesel, with a target for first power in 2027.
Deep-sea drilling impacts remain under investigation
The deployment of industrial-scale drilling and power generation on the seafloor introduces ecological variables that remain under investigation. Microbes, tubeworms, and other deep-sea organisms around hydrothermal vents rely on the chemical energy produced by these systems. Endurance Energy stated that it selected a drilling site away from vent chimneys and local animal populations to mitigate impact.
The company reported that initial monitoring showed no notable changes in the life surrounding the site, and more than 40 samples of water, rock, and minerals were sent to independent laboratories for analysis. However, the company has not yet released a peer-reviewed paper confirming these results, and the long-term effects of continuous, large-scale operations on the water column and seafloor habitat are still unknown.
“We recognize that larger systems running continuously over years could affect the surrounding water column, biological communities and seafloor habitat,” Redd said.
