Devon Project Turns Hills Into Giant Renewable Batteries

A pilot project near Plymouth is proving that you don't need mountains to store clean energy anymore.

RheEnergise's new facility at Cornwood uses a special liquid that's two and a half times denser than water to create what engineers call "high density hydro storage." The company received £8.25 million from the government to develop the technology, which is now operating successfully.

The concept builds on a 100-year-old idea called pumped storage hydropower. Traditional systems release water from high reservoirs through turbines to generate electricity, then pump it back up when power is cheap. The problem is these systems need mountains to work.

The Devon team solved this by creating what engineer Peter Hawkins calls their "secret sauce." By mixing minerals with water to make it much denser, they can generate the same power with drops as low as 100 meters. That means hills across Britain could become energy storage sites.

The demonstrator project produces 500 kilowatts of peak power and could supply 400 homes for a year if run continuously. CEO Stephen Crosher says the technology can "turn small hills into giant batteries" as part of moving away from fossil fuels.

The timing couldn't be better. Rising wholesale energy costs are pushing household bills up by 13% next month, putting energy security back in the spotlight. Storage systems like this could help stabilize prices and supply.

Professor Peter Connor from the University of Exeter explains why storage matters more than ever. Coal and gas plants can switch on and off whenever needed, but wind and solar power depend on weather conditions. As Britain transitions to renewable energy, we need ways to save clean power for when the wind stops blowing or the sun sets.

Business development manager Lizzi Gold says the technology is scalable and can work on hills as low as 100 meters. The goal is providing clean power around the clock, filling the gaps in renewable energy generation.

Why This Inspires

This project shows how old ideas can solve new problems. By reimagining century-old technology with modern innovation, engineers are making renewable energy more reliable and accessible. Instead of needing rare mountain locations, communities across Britain could host their own energy storage on ordinary hills.

The technology addresses one of the biggest challenges facing clean energy without requiring massive new infrastructure or exotic materials. It's practical, scalable, and already working.

Small hills could soon power our homes through cloudy days and calm nights.