The principle is as fantastic as it is simple. Pumped-storage power plants allow electricity to be stored and then delivered upon demand. To do this, water from a nearby lake is pumped into an elevated storage basin. When demand peaks or capacity from renewable energy sources is too low, the water can be released back to the lake via a pipeline. There, it drives a pump turbine that generates the required electricity.
All of this happens in the blink of an eye and the entire capacity of a pumped-storage power plant becomes available within a matter of minutes.
In addition to its own pumped-storage hydroelectric plant in Herdecke, RWE also holds shares in hydroelectric plants in the Black Forest and in Luxembourg.