The geothermal electricity will be delivered on a 24/7 basis, representing a huge breakthrough for UK renewable energy and geothermal power in the country in particular. Octopus Energy has signed a long-term deal to purchase at least 3 MW of constant, weather-independent power from United Downs — enough to supply 10,000 homes.
GEL has also started commercial-scale production of zero-carbon lithium carbonate at the site, delivering the key raw material that is essential for use in rechargeable batteries, including those powering electric vehicles and energy storage systems. From its February 2026 starting point, the plant has the capacity to produce 100 tonnes per annum.
At United Downs, GEL has drilled to a depth of over 5 kilometres to tap into naturally heated water exceeding 190°C — the hottest recorded in the UK. The heat generates electricity 24/7, regardless of weather. After power generation, the fluid is processed to extract battery-grade lithium carbonate before being reinjected underground in a closed loop.
The United Downs plant was developed in partnership with Exergy International, the Italian technology provider behind over 500 MW of geothermal capacity in operation worldwide. Exergy was responsible for the design, engineering, equipment supply, and construction of the ORC power plant. The core of the technology is Exergy’s Radial Outflow Turbine, particularly suited to exploit geothermal resources very efficiently thanks to its design and its extreme flexibility in adapting to changing geothermal fluid conditions in terms of flow, temperatures and constituents.
The closed-loop binary cycle technology allows conversion of geothermal heat into electricity without releasing vapour to the atmosphere, with zero emissions. The compact design of the plant also minimises environmental impact and visual footprint. The system was engineered specifically to match the unique temperature and flow conditions of the United Downs resource, optimising baseload renewable electricity generation while ensuring sustainable reinjection of geothermal fluids. Drawing on Exergy’s global experience, the company worked alongside GEL from early technical definition through to plant commissioning, helping to kick-start the UK’s first integrated deep geothermal power project and laying the groundwork for future developments.
The geothermal fluid at United Downs comes from the deepest well ever drilled on UK soil at over 5 km. The water contains over 340 parts per million (ppm) of battery-grade lithium carbonate equivalent (LCE), making it one of the highest concentrations of lithium in the world. GEL aims to scale production to over 18,000 tpa over the next decade — enough for around 250,000 EV batteries a year, equivalent to 65 percent of the UK’s 2024 BEV registrations.
The plant is a new source of home-grown, baseload renewable power: 24/7 electricity from previously untapped resources, reducing reliance on imported balancing power for wind and solar and delivering energy security and price stability for UK households.
The site is now also a critical source of lithium, which will support the UK automotive sector while meeting 2027 Rules of Origin requirements, reducing the carbon footprint of battery storage.
GEL has two additional deep geothermal sites under development in Cornwall, expected to deliver a further 10 MW of baseload power by 2030. According to the British Geological Survey, more than 200 GW of thermal heat — enough to generate power — could be produced from onshore geothermal sources in the UK, equivalent to over 100 nuclear power stations.
“We are proud to be at the forefront of this landmark step for the UK, generating electricity and lithium by harnessing the resources beneath our feet” said Dr Ryan Law, CEO of GEL. “This is a huge advancement for geothermal power in the UK and the beginning of our expansion plans. Geothermal energy and critical minerals extraction are naturally complementary as they share the same subsurface resource. The hot, mineral-rich fluids that generate clean electricity can also be processed to recover strategic materials like lithium carbonate. Therefore, collocating power and mineral extraction plants maximises investment in the wells, minimises subsurface disruption and accelerates the transition to secure domestic supply in both critical sectors. The United Downs plants prove we can do this in a way that benefits the climate, communities, and the economy.”
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