Energy storage converts energy into another form to store it and make it available again when needed. Wind and solar energy, for example, can be stored when more energy is available than is needed. During lulls and in winter, the stored energy can be used to compensate for supply bottlenecks. In this way, energy storage systems contribute to stability in the energy supply and reduce dependence on fossil fuels.
In the form of accumulators - often lithium-ion batteries - we use electrochemical energy storage devices on a daily basis. Other ways of storing electrical energy directly include high-capacity capacitors and superconducting magnetic energy storage systems, although these are still in the development stage.
Mechanical storage is one of the oldest forms of energy storage: for example, pumped storage power plants have been used for hundreds of years. In this process, water is pumped from a reservoir into a higher dam when enough energy is available. As soon as energy is needed, the dam drives a hydroelectric power plant, which provides electrical energy. In compressed air storage, on the other hand, air is highly compressed with the help of electricity so that it can be fed - mixed with gas - into a combustion chamber when needed and used to drive a gas turbine that generates electricity.
Other storage options include heat storage and the production of chemical substances such as hydrogen, green gas, or synthetic fuels. In the power-to-X process, gases, heat, or liquids can either be reused in this form or converted back into electricity.