The UK has switched on its first commercial geothermal electricity site. The United Downs facility sits near Truro in Cornwall. It generates power using hot fluid drawn from deep underground.
Developer Geothermal Engineering Ltd (GEL) said the site delivers constant output. It feeds electricity into the grid around the clock. The initial supply targets up to 10,000 homes.
GEL drilled the deepest onshore well in the UK for the project. Reports describe the borehole as more than three miles deep, or over 5 km. The company and partners spent years developing the site.
For power markets, the project adds a rare form of firm renewable supply. Wind and solar output vary with the weather. Geothermal output can remain steady, subject to plant uptime. That profile can support grid balancing needs.
Deep Drilling Unlocks Heat Near 200°C
The system circulates water through hot rocks at depth. Multiple reports place fluid temperatures above 190C °C, and near 200°C. That heat drives turbines that produce electricity.
GEL’s chief executive, Ryan Law, described the launch as the result of long development work. He said geothermal power matters because it avoids fuel price swings. He also stressed the supply runs 24/7.
The plant’s power is sold to Octopus Energy, according to multiple reports. Octopus will supply households through the national grid. A company spokesperson called the project a step toward “always-on” green power.
Costs remain a central constraint for replication. Sky News reported a project cost of about £50m. Deep drilling requires specialized equipment and risk capital. Those factors can limit the pace of rollouts. GEL has discussed additional Cornish sites in development. Two more projects are in the planning stages. The three sites are linked to a higher combined output over time.
Lithium Production Adds A Critical Minerals Angle
Alongside power generation, the site will produce battery-grade material. Reports describe commercial-scale lithium carbonate production at United Downs. GEL said the plant can produce 100 tonnes per year, which could support thousands of batteries annually.
The company has also outlined a larger ambition for later years: a target of 18,000 tonnes annually.
The UK government supported early lithium work with grant funding. ITV reported a £1.8m grant toward initial extraction costs. Policy support reflects wider concern over supply chains for battery materials.
An energy minister, Alan Whitehead, called the start-up a “ground-breaking moment” for innovation. He also referenced “zero-carbon lithium” produced domestically. The comments underscore the dual track of power and minerals.
For investors, the pairing may affect project economics. Revenue can come from electricity sales and mineral output. Co-production can help spread fixed drilling costs. It can also attract different pools of capital.
Geothermal Interest Rises As Grid Needs Grow
Interest in next-generation geothermal energy has risen globally. The International Energy Agency said financing for next-generation geothermal reached nearly $2.2bn in 2025. It described that as an 80% year-on-year increase.
The IEA also noted growing investment in conventional geothermal energy. It reported nearly $5bn for conventional geothermal power projects in 2025. The agency linked growth to better drilling methods and policy support.
In the UK, shallow geothermal has expanded faster than deep projects. Ground source heat pumps and district heating schemes already operate in parts of the country. Deep geothermal for electricity remains rare due to the upfront cost.
Supporters argue that deep projects provide system value beyond energy volumes. They can deliver controllable output and local supply security. They can also reduce exposure to imported fuels when gas prices move.
Critics focus on drilling risk and long lead times. A single well can cost tens of millions of pounds. A poor flow rate can reduce output and economics. Those risks have limited UK scale to date.
