Future deployments

Placing the geothermal plant on top of a natural hydrothermal vent was a one-time test for purely research and demonstration purposes, Redd said. His company still plans to rely on drilled wells in future deployments.

Endurance Energy also described taking steps to reduce potential environmental impacts on the seafloor and marine life. The team described choosing the “least disruptive” site for the test run and continuously monitored the process by sampling the water and recording the seafloor array of tubeworms, snails, crabs, and bacterial mats. It also checked findings against scientific sensors run by independent researchers and sent water, rock, and mineral samples for independent lab analysis.

The company’s next trial run planned for the winter of 2026—2027 will involve a refurbished and upgraded Adélie—renamed Gentoo in keeping with the penguin-inspired naming—that will aim to sustain higher power generation.

The company is also developing a larger 2-megawatt commercial generator for its first planned commercial deployment with the Kingdom of Tonga in 2027. The Polynesian island nation in the South Pacific Ocean runs its power grid primarily on imported diesel fuel, which has significantly increased in price since the United States and Israel launched their war with Iran.

“The 2 MW commercial generators will be about the size of a shipping container, and we are deploying up to six of these generators [to] offshore Tonga,” Redd told Ars. “The physical footprint of this project will be relatively small.”

Geothermal energy projects are already cost-effective on land but “on the edge of competitive pricewise,” said Horne at Stanford University. So he cautioned that any factors making geothermal more expensive would “push it to the noncompetitive side.”

Still, other customers may consider Endurance Energy’s approach if the company can demonstrate reliable operations over time with the Kingdom of Tonga. The skyrocketing cost of imported fossil fuels is a huge factor that has already spurred multiple governments to invest in more renewable energy alternatives.

“Large markets with ample offshore geothermal resources include the United States—Pacific Northwest and Alaska—Taiwan, and Japan,” Redd said. “As the technology matures, we expect to compete on cost and deliver continuous, weather-independent power to utilities and large energy users.”