A large number of different energy storage technologies have now arrived on the market. They are typically classified according to the forms of energy they provide: There are electrical, thermal, and chemical energy storage systems.
Energy storage technologies differ in the forms of energy they take up and afterwards feed back into the energy system. Their design and mode of operation, storage duration, and capacity also vary greatly depending on the individual unit.
Storage systems offer solutions for virtually any application: Technologies with short charging and discharging spans ranging in the milliseconds ensure frequency stability in the power grid. Other storage systems are specifically designed to store large amounts of energy over days or weeks, for example to bridge periods of low photovoltaic yield.
The diversity of storage technologies is also shown in the possibility of shifting between forms of energy in the storage process. Examples are power-to-gas, allowing for renewable electricity to be integrated into the transport and heating sectors; or power-to-heat, where electricity is converted to be stored thermally.