Hills Could be Used as Batteries

Another innovative idea to help store power, use it when it's needed and reduce carbon emissions.

Hills across the UK could be transformed into renewable energy “batteries” through a pioneering hydropower system embedded underground. A team of engineers have developed a system that adapts one of the oldest forms of energy storage, hydropower, to store and release electricity from gentle slopes rather than requiring steep dam walls and mountains.


The company behind the project, RheEnergise, said its plan could see around 700 sites across the country host subterranean hydro projects without spoiling the scenery. They would be much quicker and far cheaper to build than traditional hydropower dams and also lead to fewer negative environmental impacts.


The hillside projects would mimic the UK’s traditional hydropower plants by using surplus electricity to pump water uphill, and later releasing the water back down the hill through turbines to generate electricity when needed. But the “high-intensity” hydro projects use a mineral-rich fluid, which has more than two and a half times the density of water, to create the same amount of electricity from slopes which are less than half as high.


RheEnergise says each installation would pump the dense fluid up a hill with a height of 200 metres, at times of low electricity demand. It would be held in an underground storage tank larger than an Olympic-size swimming pool.

Then when extra electricity is required, the fluid would be allowed to flow back down the hill, over generating turbines, to effectively return the electricity used by its pumps earlier in the day back to the grid.


Stephen Crosher, chief executive of RheEnergise, said its high-intensity hydro projects could be built in one to two years and hopes to build the first plant in mid-2023.

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