UK's First Deep Geothermal Plant Powers 10,000 Homes

Deep beneath the Cornwall countryside, water heated to 190°C is now generating round-the-clock electricity for thousands of British homes. After nearly two decades of development, the United Downs geothermal plant has officially begun operations as the UK's first facility to convert underground heat into renewable power.

The project required drilling over three miles down, the deepest onshore well ever drilled on UK soil. That extreme depth accesses naturally heated water hot enough to drive turbines and generate electricity 24 hours a day, regardless of weather conditions.

Geothermal Engineering Ltd., the company behind the project, brought the plant online in February 2026 for around $59 million. Energy provider Octopus Energy purchased the power and will distribute it through the national grid to about 10,000 households.

But electricity is only half the story. The water pumped from underground contains one of the highest lithium concentrations in the world, making this the UK's first domestic lithium source.

The plant will produce 100 tons of lithium carbonate annually starting this year. That critical mineral powers rechargeable batteries in electric vehicles and energy storage systems, technologies essential for the green transition.

Dr. Ryan Law, CEO of Geothermal Engineering Ltd., called the plant opening a "huge advancement for geothermal power in the UK." He explained that extracting both energy and minerals from the same underground source maximizes investment while minimizing environmental disruption.

The Ripple Effect

This facility represents more than clean energy for Cornwall. It demonstrates how Britain can reduce dependence on imported minerals while building energy security through homegrown renewable sources.

The technology differs from ground source heat pumps already used across the UK. Those systems tap shallow underground warmth for heating, but United Downs drilled deep enough to reach temperatures that generate actual electricity.

Octopus Energy founder Greg Jackson emphasized that UK energy bills remain too high and the solution is "more homegrown, renewable energy." He noted that deep geothermal represents "a clean, constant energy source right beneath our feet."

Geothermal Engineering Ltd. has two additional sites planned for development. While one site initially faced rejection over environmental concerns, the company is appealing the decision.

The Cornwall plant proves that renewable energy doesn't have to wait for sunny days or windy weather to keep the lights on.