INDEPENDENT.CO.UK

A giant “water battery” capable of storing as much energy as 400,000 electric car batteries has been switched on in Switzerland.

The €2 billion project, located nearly 600 metres beneath the Swiss Alps, was under construction for 14 years.

Its 20 million kWh capacity will allow excess energy produced from renewable sources to be stored for future use, thus helping to stabilise the electricity grid and reduce reliance on fossil fuels.

The hydro battery works by using the excess energy to pump water between two separate reservoirs at different altitudes in the Swiss canton of Valais.

Six pump turbines send water from the lower reservoir of Emosson to the upper reservoir of Emosson Vieux during times of overproduction.