[en] This comprehensive article takes a look at the long-established technique of using pumped storage schemes to temporarily store electricity. Here, excess power is used to pump water back into high-level reservoirs during low-load periods so that it can be used to generate electricity during peak periods. Ecological and energy-loss aspects are discussed as are the objections raised by environmental agencies. An overview of the present situation and the operation of such installations in Switzerland is provided. Future developments in this area and the role played in the European power system are discussed. Comparisons are made between hydro-electric peak power production and that using gas turbines and other systems. In particular, the efficiencies and the carbon dioxide loading involved are looked at. Also, the situation with power generation using new renewables is examined and the economic prerequisites for the operation of such schemes are looked at