Endurance Energy Generates First Net-Positive Power From Underwater Volcano

Seattle-based startup Endurance Energy achieved a significant milestone in September 2026, successfully completing a "proof point" test of its subsea geothermal power plant, Adélie[1][4][5][6][7][8][9][10][11][12]. The plant generated net-positive electricity for 8.7 seconds, reaching a peak output of 16.5 kilowatts[7][12]. This event marks the first end-to-end demonstration of subsea geothermal power[1][4][6][7][10][12].

This development matters because it offers a potential source of continuous, baseload clean energy that could reduce reliance on fossil fuels, particularly for remote islands and Pacific Rim nations[1][3][4][5][6][10][12]. Subsea geothermal technology aims to provide consistent power, unlike intermittent renewable sources like solar and wind[12].

What the Records Show

The test took place at Axial Seamount, an active underwater volcano located approximately 300 miles off the coast of Oregon[1][4][5][6][7][8][9][10][11][12]. Endurance Energy deployed its 3-ton geothermal generator, Adélie, at a depth of about 5,000 feet, which is approximately 1,500 meters[4][7][9][12]. During the deployment, the company drilled the world's first offshore geothermal well[4][6][7][10][11]. However, this newly drilled well proved too restrictive to power the plant as intended[7][9][12]. To proceed, Adélie connected to a natural hydrothermal vent that was flowing at approximately 281°C (538°F)[7][12]. The test demonstrated the full chain required for subsea geothermal power, including drilling a well, operating a power plant on the seafloor, converting heat into electricity, and communicating with the system from a remote location[4][6][10]. The power plant was operated in real-time from Seattle using a subsea fiber-optic network[4][6][7][10][12]. During the net-positive run, the turbine reached about 26,000 rotations per minute[7][12]. The operation was cut short due to a battery overcurrent protection system and a subsequent power cable failure during a restart attempt[7][9][12].

Timeline

Endurance Energy was founded in January 2025 by Andrew Redd, a former SpaceX engineer[4][5][6][9][10][12]. The company made its first deep-sea deployment in August 2025[4][6][10]. By June 2026, Endurance Energy had raised $63 million in total funding, which included a $54 million Series A round[5][7][9][12]. This Series A round was led by Founders Fund, with additional investments from Felicis, Voyager Ventures, Riot Ventures, and Construct Capital, and continued support from Point72 Ventures, First Round Capital, and Ascend[3]. The Adélie test at Axial Seamount occurred in September 2026[1][4][5][6][7][8][9][10][11][12]. The company plans to deploy an upgraded system named Gentoo in winter 2026-2027[7][12]. The ultimate goal is to deploy its first commercial 2-megawatt plant, Leopard, to deliver power in Tonga by 2027[5][7][12].

What Changed

The successful test of Adélie represents the first time a subsea geothermal plant has demonstrated net-positive electricity generation in an end-to-end system[1][4][6][7][10][12]. This proof point shows the potential for harnessing heat from active underwater volcanoes to provide continuous, clean electricity[1][4][6][10]. The company aims to make this technology a viable option for decarbonizing coastal regions around the Pacific and worldwide[3][4][6][10].

What the Subject Has Said Publicly

Andrew Redd, founder and CEO of Endurance Energy, stated, "On Sept. 27, we put a power plant on an active underwater volcano and made power"[4][6][10]. He also described the event as "our first end-to-end test," adding, "We now know, firsthand, what works at depth, what needs to be improved, and how to build the next system for sustained commercial generation"[4][6][10]. Redd also remarked, "Adélie made it exist, and now we know it's possible"[5]. He expressed his aim to pursue something that is both beneficial for the world and compelling from an employee perspective[9].

What We Could Not Confirm

We could not confirm the exact cause or detailed technical specifications of the power cable failure that ended the Adélie test[7][9][12]. We also could not confirm the duration for which future systems are expected to generate continuous power, beyond the brief net-positive period of the Adélie test[7][12].