Made in the heart of the Swiss Alps, a huge “water battery” is now operational. The principle of operation is simple, but at the same time ingenious: on the mountain there are two large water tanks of different heights; When electricity is needed, from the tank on the top level, the water passes to the bottom tank through a turbine that generates electricity, just as it does in conventional hydropower plants. On the other hand, when there is excess power in the electrical network, hydraulic pumps take care of returning the water from the lower tank to the upper tank.
The production capacity of electricity is 900 MW, which is obtained through six turbines and is enough to power 900 thousand homes, while the storage capacity is 20 million kWh.
14 years of construction
The water coil was designed and built by the Swiss company Nant de Drance. The core is located 600 meters underground between the reservoirs of Emosson and Vieux Emosson in the canton of Valais. The construction took 14 years, due to significant engineering and logistical problems to be resolved, including for example the need to build a total of 18 kilometers of the tunnel under the Alps, which is necessary for the transportation of building materials. In the center of the plant there is a spacious chamber 200 meters long and 32 wide, which contains the necessary pumps to “recharge the battery”, to transfer water from the lower tank to the upper tank.
Increase tank volume
In the years between 2012 and 2016, the height of the Vieux Emosson Dam was increased by 20 meters to allow the basins to store more water and generate more energy.
Thanks to the battery, it will be possible to produce part of the needs of the Swiss and European electricity grid in times of greatest need, while storing electricity instead for the times when the demand is least.