A record high 5 GW of battery storage capacity was added worldwide in 2020, bringing the total capacity to around 17 GW

Energy storage allows for flexibility in the timing of when energy is supplied and when it is used. Energy storage comes in a number of forms, including chemical, kinetic, thermal, gravitational potential, electromagnetic, electrochemical and osmotic potential. The choice of storage solution depends on location as well as reserve service required, since different technologies can provide different capacities and durations of storage. Storage of solid, liquid and gaseous fuels has been commonplace for centuries; as the low carbon transition requires integration of increasing intermittent renewable sources into the system, energy storage is becoming integral for reducing dependency on fossil fuels and achieving a flexible, resilient energy network. Strategic placement of storage also gives the potential to avoid otherwise necessary network upgrades and curtailment of expensive assets. Greater connectivity between different energy networks, i.e. interconnection across national grids, can allow for security of supply without needing additional generation capacity.

Energy storage has applications varying from small-scale local systems in homes or commercial buildings – which are becoming increasingly common alongside the rise of distributed generation – to utility-scale storage systems. Common examples of energy storage include batteries (mainly lithium-ion) which store electricity as chemical energy, pumped hydroelectric storage systems which store gravitational potential energy in elevated reservoirs, and ice storage tanks which store thermal energy by freezing water with cheaper energy at night to meet peak cooling demand in daytime. Surplus renewable electricity can also be used to produce energy carriers like hydrogen, enabling the storage of renewable energy for long periods. Electric vehicles can also function as storage systems, since electricity can be transferred both to and from the batteries of plugged-in vehicles when needed. With energy storage expected to play a greater role towards a low-carbon and sustainable energy future, various storage technologies must be evaluated to balance the trade-offs between life-cycle cost, efficiency, material sustainability and safety.

Learn more about storage by reading our Energy Insights.

Read our New Energy World articles on how energy storage fits into strategies for carbon reduction.

Learn about recent public funding for research and development of energy storage on our policy milestone calendar.