Pumped Storage Hydropower

Pumped storage hydropower is the most important of the energy storage technologies in terms of installed capacity and accounts for around 95% of all global electricity storage capacity. A pumped storage plant is a hydropower plant with two reservoirs separated in height. To store energy, water is pumped from the lower reservoir into the upper. This energy can be released again by allowing it to fall through a turbine and back into the lower reservoir. Many plants of this type were built to support nuclear power generation in the 1960s and 1970s. More recently there has been interest in using them to support wind and solar power generation. Plant efficiency improves with the height difference between the two reservoirs. Modern plants usually use combined pump turbines.