The market for energy storage technologies knows a large number of different technical approaches. These are typically classified according to the form of energy they provide: electrical, thermal, and chemical systems. But energy storages may also differ in which form of energy they feed back into the energy system. Design, mode of operation, storage duration, and capacity also vary greatly depending on the individual unit.
Storage systems therefore 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 storages designs specifically allow for the storage of large amounts of energy over days or weeks, for example to bridge periods of low photovoltaic yield.
The technological diversity also becomes evident in the possibility of shifting between different 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 for thermal storage.