Switzerland is adding a much-needed cog to its energy supply with an underground hydropower project that can store enough electricity to charge 400,000 automobile batteries at the same time.
The 2.2 billion Swiss franc ($2.30 billion) Nant de Drance plant in the canton of Valais, which opened in July, was designed to work like a big battery, according to its developers.
Its six turbines, located 600 meters underground between the Emosson and Vieux Emosson reservoirs, have a capacity of 900 MW, making it one of Europe’s most powerful pumped storage facilities.
Nant de Drance generates energy from hydropower at peak demand. When wind and solar production exceeds demand, the facility stores the excess power by pumping water into the higher Vieux Emosson reservoir.
“There are losses, as with any storage method, but the yield is quite high. We have almost 80% efficiency over the competition “On a visit this week, director Alain Sauthier told Reuters
The factory, which took 14 years to construct, will be formally inaugurated next month.
The transition from full pumping mode to full power generation takes less than five minutes. The amount of water going through its turbines at 360 cubic metres per second corresponds to the summer flow of the Rhone river through Geneva.
“The amount of energy that can actually be stored in this facility is simply gigantic, about 20 gigawatt hours,” Sauthier added. “This means that with a full tank in Vieux Emosson, you can recharge 400,000 electric car batteries simultaneously.”
According to Sauthier, the facility often pumps water into storage in the afternoon, at night, and on weekends, then produces electricity in the morning and evening when costs are higher.
“I would say it’s not only important for Switzerland, it’s also an important plant at European level because it will contribute to the stability of the network in Europe and to the security of supply in Europe,” he added.
That is no small accomplishment at a time when Switzerland threatens rolling four-hour regional blackouts if Europe’s energy crisis causes winter power shortages.