A new chapter for geothermal energy in the United Kingdom has begun.
The United Downs geothermal plant in Cornwall is now officially operational, delivering the country’s first-ever 24/7 renewable geothermal electricity. Even more significantly, the project combines clean power generation with commercial-scale production of zero-carbon lithium carbonate — demonstrating how a single geothermal resource can support both the energy transition and the electric mobility value chain.
For Exergy, this milestone represents not only a technological achievement, but also a strategic step forward in expanding geothermal deployment into new markets.
Unlocking Deep Geothermal Potential
The United Downs project taps geothermal fluids from depths exceeding 5 kilometres, where temperatures rise above 190°C — the highest ever recorded in the UK. (Source : GEL) The plant operates in a fully closed-loop configuration: geothermal fluid is brought to the surface to generate electricity, then processed to extract lithium, and finally reinjected underground. This approach ensures zero atmospheric emissions and long-term sustainability of the reservoir.
The result is reliable, weather-independent baseload renewable power — a critical component of resilient and decarbonised energy systems.
Exergy’s Technology at the Core
Exergy acted as EPC contractor for the power plant, managing engineering, equipment supply, construction and commissioning. At the heart of the facility is Exergy’s proprietary Organic Rankine Cycle (ORC) technology, equipped with the Radial Outflow Turbine. The system was specifically engineered to maximise efficiency and operational flexibility under the unique geothermal conditions of the United Downs reservoir.
Thanks to its advanced binary cycle configuration, the plant delivers:
- High thermodynamic efficiency
- Operational flexibility
- Minimal environmental footprint
- Zero emissions to atmosphere
This project confirms the adaptability of Exergy’s technology to challenging deep geothermal resources and emerging geothermal markets.
Power and Lithium from the Same Resource
Beyond electricity generation, United Downs also produces battery-grade lithium carbonate, with an initial capacity of 100 tonnes per year. Plans are already in place to scale production to more than 18,000 tonnes annually within the next decade — potentially supplying lithium for around 250,000 electric vehicles per year.
This integrated model highlights geothermal energy’s unique ability to deliver multiple strategic benefits:
- Clean, always-on renewable power
- Domestic supply of critical raw materials
- Long-term energy price stability
A Milestone for Geothermal in New Markets
The successful commissioning of United Downs marks the first operational geothermal power plant in the UK — a breakthrough that could pave the way for further deep geothermal development across the country.
For Exergy, it is another demonstration of Italian engineering excellence supporting the global energy transition. With more than 500 MW installed worldwide, Exergy continues to enable countries to unlock the full potential of geothermal energy through efficient, flexible and sustainable ORC solutions.
We would like to thank all Exergy colleagues, partners and stakeholders whose expertise and dedication made the successful start-up of this ambitious project possible
