In a milestone for British renewable energy, the first deep geothermal electricity plant in the UK at United Downs near Redruth, Cornwall, has begun delivering continuous power to the national grid alongside lithium extraction at the site. This marks an important step in clean energy, local economic regeneration, and critical mineral supply in the UK.

Developed and operated by Geothermal Engineering Ltd (GEL), the project is producing approximately 3 MW of baseload electricity – enough to power around 10,000 homes – while simultaneously extracting zero-carbon lithium carbonate from geothermal brines.

Commissioning of the first deep geothermal power plant in the UK also positions Cornwall at the forefront of next-generation geothermal systems in Europe. This is as it combines clean power generation with critical mineral extraction in a single integrated asset.

What this means for the UK energy sector

United Downs represents the first fully commercial deep geothermal electricity plant in the UK. Unlike shallow geothermal heating systems, this project taps high-temperature granite reservoirs more than 5 km below ground, enabling continuous 24/7 power generation independent of weather conditions.

The first deep geothermal power plant in the UK also operates under a long-term power purchase agreement (PPA) with the UK’s most awarded energy supplier, Octopus Energy. This will ensure stable offtake and revenue security. Technology for electricity conversion is supplied by Exergy International, using an Organic Rankine Cycle (ORC) binary system tailored for medium-enthalpy geothermal resources.

Financial backing for United Downs has come from private investors including Kerogen Capital (via Kerogen-CX) and Thrive Renewables plc. This is alongside public funding support from the European Regional Development Fund (ERDF) and UK government programs.

The project also secured a Contract for Difference (CfD) under the UK government’s renewable support mechanism. The CfD provides 15-year price stability for generated electricity from United Downs deep geothermal power project.

Project factsheet for United Downs deep geothermal power site in the UK

Location: United Downs Industrial Estate, near Redruth, Cornwall

Developer & Operator: Geothermal Engineering Ltd (GEL)

Installed Electrical Capacity: 3 MW (baseload)

Equivalent Homes Powered: 10,000

Technology: Enhanced Geothermal System (EGS) with Organic Rankine Cycle (ORC)

Production Well Depth: 5,275 m (deepest onshore UK well)

Injection Well Depth: 2,393 m

Reservoir Temperature: 190 degrees Celsius

Lithium Output: 100 tons per annum initial capacity

Electricity Offtaker: Octopus Energy

Total Project Cost: £50 million

Revenue Streams:

• Electricity with CfD-backed PPA
• Lithium carbonate sales

Project team behind United Downs deep geothermal electricity plant and their roles

Geothermal Engineering Ltd (GEL) – Project developer, reservoir engineering lead, drilling oversight, plant operator and lithium extraction integration.

Exergy International – Supplier of the Organic Rankine Cycle power plant, turbine technology provider, EPC support for surface generation systems.

Octopus Energy – Long-term power offtaker under PPA, retail integration of geothermal electricity into UK supply portfolio.

Kerogen Capital (Kerogen-CX platform) – Private equity investor providing capital.

Thrive Renewables plc – Institutional renewable energy investor supporting development and scale-up.

European Regional Development Fund (ERDF) – Public capital grant contributor toward drilling and infrastructure.

Cornwall Council – Regional authority and co-funding partner.

UK Department for Energy Security and Net Zero – Policy support and CfD award authority.

Beta Design Consultants (BDC) – Civil and structural engineering consultancy for surface plant infrastructure.

Finance and capital structure for the first deep geothermal power plant in the UK at Cornwall

The total project development cost is estimated at £50 million, structured across:

• Equity investment from Kerogen Capital, Thrive Renewables
• Public grant funding from ERDF, local authority contributions
• UK Government Contract for Difference (CfD) guaranteeing strike price stability
• Long-term PPA revenue from Octopus Energy
• Future lithium sales contracts targeting UK/EU battery manufacturers

Additionally, the integration of United Downs deep geothermal power project with lithium production strengthens the project’s economics. This is by diversifying revenue beyond electricity. The idea is also quite rare for geothermal projects globally.

United Downs deep geothermal electricity plant: Technical overview

The plant operates a closed-loop Enhanced Geothermal System:

• Cold water injected into fractured granite reservoir
• Heated to 190 °C at depth
• Produced to surface through 5.2 km well
• Drives ORC turbine (binary cycle)
• Lithium extracted from brine
• Fluid re-injected to maintain reservoir pressure

The ORC system supplied by Exergy uses a radial outflow turbine optimized for medium-temperature geothermal resources, maximizing efficiency while maintaining zero atmospheric emissions.

Outlook on United Downs and the UK energy sector

Two other geothermal projects are also under development in Cornwall, potentially adding 10 MW of additional baseload capacity by 2030. The British Geological Survey has also indicated that UK geothermal potential could exceed 200 GW of thermal resource, making geothermal a long-term complement to wind, solar, advanced modular reactors and nuclear in the UK.

United Downs, a first in the UK, serves as a pilot for a scalable, geothermal projects combining electricity generation and critical mineral extraction.