Subsea Geothermal Prototype Produces a Brief Net-Positive Power Result

The Short Version

Endurance Energy has tested a subsea geothermal power prototype near Axial Seamount in the northeast Pacific Ocean, Ars Technica reports. The three-ton plant was deployed for three weeks in September, but produced less than ten seconds of net-positive electricity. That brief result is the reported milestone, rather than three weeks of continuous generation.

Why It Matters

The experiment provides an early indication that this approach can produce net-positive electricity underwater. Duration matters, though: a short interval does not establish that a plant can keep supplying useful power. The deployment period and the positive-output period describe different parts of the test.

The Bigger Picture

The Seattle startup wants to commercialize subsea geothermal power for customers including Pacific island nations seeking alternatives to imported fossil fuels. That is a future market goal.

Founder and CEO Andrew Redd told Ars that cold seawater provides cooling while ocean pressure keeps the system and well pressurized, potentially allowing compact plants. This explains the company’s rationale for working underwater; it does not establish the cost or reliability of a commercial installation.

What to Watch

Longer periods of net-positive operation would help connect this prototype result to dependable service. The available account gives no output wattage, total energy delivered or detailed explanation of which energy inputs are counted in the net-positive figure. Those measurements, alongside costs and repeatability, would make the next demonstration easier to assess.

What would you want to see from the next test before viewing subsea geothermal power as a practical energy source?