According to experts, global climate change is the greatest threat to survival on earth in the 21st century. To mitigate this danger, the use of renewable energies is mandatory. However, these forms of energy are dependent on the supply of sunshine and wind and are therefore not always available. In order to be able to provide electrical energy around the clock, so-called pumped storage hydroelectric power plants have proven their usefulness for energy storage. These systems can switch between two operating modes (see graphic):
- if there is an excess of energy, the system is operated as a pump that transports water into an elevated reservoir
- if energy is required, the system is operated as a power plant, which converts the potential energy of the water in the elevated reservoir into electrical power via a turbine.