he United Downs deep geothermal project is the first geothermal power plant in the UK. It is funded by a mixture of public and private funds to include the European Regional Development Fund, Cornwall Council and Thrive Renewables Plc. The aim of the project is to produce power and heat from the hot granite rocks beneath Cornwall at the United Downs Industrial Site near Redruth. The GEL flagship development site United Downs is in the heart of west Cornwall, just a few miles southwest of Truro. United Downs is the home of the hottest and deepest onshore well in the UK measuring a total depth of 5057m.
Geothermal power projects use a small amount of land for producing 5mwe with a carbon footprint of 5g – 15g of CO2 per kw. In 2023 GEL was awarded the first Contracts for Differences (CfD) from the UK Government, ensuring a set price for electricity for 15 years. After electricity has been produced, there is the possibility of using the surplus heat for industry, agriculture, or space heating.
It has been known since the mid-1800s that there is lithium in geothermal fluid in Cornwall, GEL has discovered high concentrations at their United Downs site. The Automotive Transformation Fund (ATF) has enabled GEL to invest in a demonstration lithium extraction plan. Two deep, directional wells have successfully been drilled; the production well to a depth of 5275m and the injection well to 2393m. Both wells have intersected the target Porthtowan Fault Zone located approximately 800m to the west of the site.
The £50m facility, developed by Geothermal Engineering Ltd (GEL), draws superheated water exceeding 190°C from the UK’s deepest borehole at more than 5km underground. The heat is used to drive turbines generating 3 MW of continuous electricity. Octopus Energy has signed a long-term agreement to deliver the plant’s output into the national grid.
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