UK-based energy storage developer RheEnergise has brought its first High-Density Hydro® (HD Hydro) energy storage project into full power operation at Cornwood, near Plymouth in Devon. The company said the pilot facility is now operating at its designed output on a consistent basis, marking a key step toward commercial deployment.
The Cornwood project is RheEnergise’s first demonstration of its long-duration energy storage (LDES) technology. According to the company, performance data from the site will be used to support financing and development of larger commercial projects in the UK and international markets.
HD Hydro uses a proprietary high-density, low-viscosity fluid that is heavier than water. The system operates in a similar way to conventional pumped hydro storage but requires significantly lower elevation differences between reservoirs. This allows projects to be developed on smaller hills rather than mountainous terrain, expanding the range of potential sites.
RheEnergise chief executive Stephen Crosher said the company has now validated the technology under operational conditions. “Reaching full power confirms that the system is performing as expected and reduces technical risk for future commercial projects,” he said. “This enables us to move forward with large-scale deployments in the UK and overseas.”
The company plans to develop commercial projects ranging from 10 MW to 100 MW, with storage durations between six and 20 hours. RheEnergise said a typical 40 MW project could supply electricity equivalent to the annual consumption of approximately 40,000 homes.
The Cornwood facility has a peak output of 500 kW. When operated continuously, it can generate enough electricity to supply around 400 homes annually. The project supports energy demand at Sibelco’s nearby kaolin mining operation and contributes to the company’s decarbonisation strategy.
Sibelco vice-president of operations Ben Uphill said the project aligns with the company’s sustainability objectives and could have applications across the mining and industrial sectors.
Funding for the Cornwood project was provided in part by the UK Government through the Department for Energy Security and Net Zero’s Net Zero Innovation Portfolio programme. The scheme is part of a £1 billion national funding initiative supporting low-carbon technology development.
Patrick Vallance, UK Minister for Science, Innovation, Research and Nuclear, said long-duration energy storage will play an increasingly important role as renewable generation expands and electricity demand grows.
RheEnergise said it is targeting operation of its first commercial-scale HD Hydro project within three years. The company is currently assessing potential sites in the UK, continental Europe — including Italy, Poland and Spain — and North America.
Construction of the Cornwood facility was carried out by D.A. Macdonald Ltd, Friendship Engineering and Drew & Co, working alongside RheEnergise’s in-house engineering team.
