In early 2024 Geothermal Engineering Ltd (GEL) was building the surface power plant at United Downs, near Redruth in Cornwall, with the aim of producing the UK’s first geothermal electricity by the end of that year. The hard part underground was already done: two deep wells had been drilled between late 2018 and mid-2019, including a production well reaching 5,275 metres, the deepest onshore well ever drilled in the UK. Testing had found water at roughly 180–190°C circulating through fractured granite.
The project had several firsts behind it. In September 2023 the government’s fifth Contracts for Difference auction awarded the first ever CfDs for geothermal power, all three to GEL projects: United Downs (2 MW), and two planned sites at Manhay and Penhallow (5 MW each), at a strike price of £119/MWh in 2012 prices. A CfD guarantees a fixed price for electricity over 15 years, which made the plant financeable.
The generating equipment came from Exergy International, an Italian specialist. In July 2023 GEL contracted Exergy to supply an Organic Rankine Cycle (ORC) unit rated at about 3 MWe gross. In a binary ORC plant the hot brine never touches the turbine: it heats a separate working fluid with a low boiling point, which drives the turbine, and the cooled brine is pumped back underground. The plant uses air cooling, so it does not consume water. The two companies also signed a longer-term partnership covering possible further projects in the UK and abroad. Investor Thrive Renewables had provided the first commercial funding in 2020 and added £3 million in 2023.
A second attraction was lithium. Tests showed the brine contains around 340 parts per million of lithium, high by European standards, raising the prospect of producing battery-grade material from the same wells.
What happened next
- August 2024: The turbine was installed. GEL now forecast about 2 MWe of baseload output and moved first power to early 2025.
- 2025: The schedule slipped again. Industry reporting later attributed delays to supply-chain problems that followed the pandemic. Thrive made a further investment in 2025 to complete construction.
- Late February 2026: United Downs was synchronised with the grid and began exporting electricity, almost two years later than first planned. It became the UK’s first geothermal power station. Octopus Energy agreed a long-term deal to buy its output. Total development cost has been reported at around £50 million, part-funded by UK and EU grants.
- February 2026: GEL also began commercial-scale production of lithium carbonate at the site, with a stated capacity of 100 tonnes a year. The company says it wants to grow this substantially over the next decade; that remains a target, not a plan with consent and funding.
- October 2026: United Downs is operating. GEL says its other two Cornwall sites, Manhay and Penhallow, which have planning permission and CfDs, could add around 10 MW by 2030. We found no confirmation that drilling has started at either.
The plant is small. At 2–3 MW it is smaller than one large modern offshore wind turbine. What it proves is that deep geothermal power works in British granite, that the permitting route exists, and that one set of wells can yield both electricity and a critical mineral. The planned supply of heat to nearby housing at Langarth Garden Village has not yet been reported as delivered.
You can read more about the technology on our geothermal energy page and in our history of geothermal development.
Why it matters for UK energy
Geothermal power runs around the clock regardless of weather, which makes even small amounts useful in a grid dominated by wind and solar. United Downs has turned a long-discussed Cornish resource into a working plant, but scaling it up will depend on the next wells being drilled faster and more cheaply than the first.