UK Switches On Its First Geothermal Power Plant in Cornwall, Adding Baseload Renewable Power and Domestic Lithium in One Project
GEL's United Downs facility drills 5km into granite to generate 3MW of constant power and extract battery-grade lithium — a UK first after two decades of development.
Overview
The United Kingdom’s first deep geothermal power plant began generating electricity on 26 February 2026 at United Downs near Redruth in Cornwall. Operated by Geothermal Energy Lithium (GEL), the £50 million facility draws superheated water from more than five kilometres underground to run turbines supplying around 10,000 homes — marking the end of a two-decade effort to prove that Britain’s geology could sustain commercial geothermal generation.
The project is unusual even by global geothermal standards: the same hot fluid that drives the turbines contains battery-grade lithium at concentrations exceeding 340 parts per million, making United Downs simultaneously the country’s first commercial geothermal lithium carbonate producer.
What We Know
Power generation
According to Interesting Engineering, the facility taps into Cornish granite roughly three miles below the surface, where rock temperatures approach 190°C — the highest recorded in any UK borehole. A closed-loop binary-cycle Organic Rankine Cycle (ORC) turbine supplied by Italian technology firm Exergy International converts the thermal energy into a minimum of 3 megawatts of continuous electrical output.
Octopus Energy has signed a long-term power purchase agreement (PPA) to take that output directly into the national grid. Greg Jackson, founder of Octopus Energy, described geothermal as “clean, constant energy right beneath our feet.”
Lithium production
GEL began commercial-scale lithium carbonate extraction in February 2026 alongside the electricity operations. The geothermal brine, which is reinjected into the rock after processing to maintain the closed loop, currently yields approximately 100 tonnes of battery-grade lithium carbonate per year — sufficient for around 1,400 electric vehicle batteries as reported by Interesting Engineering. GEL has stated a target of scaling extraction to 18,000 tonnes annually within a decade, which the company calculates would cover roughly 65 percent of the UK’s 2024 battery electric vehicle demand.
Financing and government backing
The project attracted private investment from Kerogen-CX and Thrive Renewables, with the UK government’s Automotive Transformation Fund contributing to lithium operations and a £1.8 million grant covering roughly half the initial mineral extraction costs. Total project development cost stands at approximately £50 million.
Chancellor Rachel Reeves characterised the launch as “a huge opportunity for Cornwall to unlock investment, drive economic growth, support jobs.” Energy Security Minister Alan Whitehead called it “a ground breaking moment for UK energy innovation.”
Expansion plans
GEL is currently developing two additional deep geothermal sites in Cornwall, with the combined pair expected to add a further 10 megawatts of baseload capacity to the grid by 2030.
What We Don’t Know
The plant’s current output of 3 MW represents less than 0.01 percent of UK national electricity demand. Whether United Downs can catalyse a broader geothermal build-out depends on questions that remain open: how far drilling costs can fall with volume, whether the geology in other parts of Cornwall and beyond the county will prove as permissive as United Downs, and whether government policy will evolve to provide the Contracts for Difference or similar instruments that wind and solar have long relied on to attract capital at scale.
Experts cited in industry coverage caution that geothermal remains early in its cost-reduction curve. Wind and solar each required roughly two decades of deployment before prices fell dramatically; geothermal is at an analogous early stage in the UK market.
Analysis
United Downs matters as a proof of concept as much as an energy asset. Geothermal’s defining advantage over wind and solar is dispatchability: it generates at a constant rate regardless of weather, addressing a grid stability challenge that becomes more acute as the UK targets 100 percent clean electricity. The British Geological Survey has estimated UK onshore geothermal sources could theoretically yield more than 200 gigawatts of thermal energy — though that figure describes the resource, not what is economically extractable.
The IEA’s 2024 report on the future of geothermal energy found that next-generation geothermal could meet up to 15 percent of global electricity demand growth to 2050 if cost reductions materialise, with cumulative investment potentially reaching USD 1 trillion by 2035. The agency also noted that investment in next-generation geothermal has been rising sharply, with the sector seeing roughly 80 percent annual growth in deep geothermal investment since 2018, driven partly by demand from data centres and AI infrastructure operators seeking carbon-neutral baseload power.
The dual-output model at United Downs — electricity plus critical minerals — gives the project a revenue diversification that pure-power geothermal developments lack. Domestic lithium supply has become a strategic priority for European governments trying to reduce dependence on imports for battery supply chains. Whether that combined value proposition proves replicable at the scale needed to move the needle on UK energy supply remains the central question for the sector.