RheEnergise Cleantech Energy Storage Startup Raises €2.5 Million Funding

The UK-based company is developing a long-duration energy storage system called High-Density Hydro (HD Hydro).

The system works by pumping a special high-density fluid uphill to storage tanks when energy demand is low. When demand increases and energy prices rise, the fluid flows back downhill through turbines to generate electricity.

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Unlike traditional pumped hydro, RheEnergise’s solution works on smaller hills — needing just 100 meters of elevation. This opens up many more potential project sites in the UK and globally.

Projects can range from 10 MW to 100 MW, offering scalable, flexible storage that helps balance the grid and support renewable energy.

Stephen Crosher, Chief Executive of RheEnergise, said: “The receipt of the EIC Accelerator grant is hugely welcome, as the EIC acknowledges the quality of our R&D to date, and the commercial prospects for our LDES technology to be deployed.

With the start of pumping of our High-Density Fluid soon to commence at our demonstrator energy storage plant on the outskirts of Plymouth, and the encouraging global interest that is being shown in our LDES technology, we are in a strong position to be one of the UK’s leading green energy unicorns.”

RheEnergise’s LDES (Long Duration Energy Storage) demo project in Cornwood near Plymouth, Devon is backed by funding from the UK Department of Energy Security & Net Zero.

The company also has agreements to roll out its energy storage technology in the UK, South America, Australia, and mainland Europe.

About RheEnergise

RheEnergise is revolutionising pumped hydro storage with its High-Density Hydro® technology. Using a special fluid 2.5x denser than water, it delivers more power and energy on smaller hills. Scalable from 10MW to 100MW, the system is eco-friendly, low-cost, and fast to deploy—unlocking more storage sites worldwide.