No wind, little sun - to ensure a stable power supply with renewable energies, all storage options are in demand. This is where the not new, but proven reliable pumped storage plants (PSP) come into play. This is the only technology currently capable of storing large amounts of electricity, and it also has the advantage that it can make the energy available quickly. The enormous potential of these storage giants for the energy transition prompted the German Energy Agency dena to establish the "Pumped Storage Plants Platform" project. In order to push the technology forward, however, the framework conditions must be improved quickly. According to dena, costs such as double grid charges jeopardise economic viability.

Pleasing gradient
Those with mountains have a clear advantage: PSPs are naturally found in areas with slopes. Water is ideally pumped with surplus solar and wind energy from a lower-lying storage basin to a higher-lying one, where it waits to be used. When needed, the water flows back downhill within a few minutes and uses turbines and generators to produce electrical power that is used to regulate the grid. In Germany, according to the Federal Network Agency, 26 pumped storage power plants (47 turbines) create a total output of 6,357 MW, each with a net nominal output of at least 10 MW. The PSP Goldisthal in the Thüringer Schiefergebirge has a capacity of 1,060 MW, making it the largest hydropower plant in Germany and one of the most important in Europe. The superlatives of PSP are found in China and the USA, with the mammoth plant in Fengning, China, reaching a capacity of 3,600 MW.

New PSP in the pipeline
Despite some obstacles, the current situation favours the construction of new PSW. For example, the PSP in Riedl, Bavaria, which has been in the planning stage for ten years, is finally to be realised. The public consultation and hearing of those affected will take place before the end of the year.