Grid energy storage

Grid energy storage (also called large-scale energy storage) is a collection of methods used for energy storage on a large scale within an electrical power grid. Electrical energy is stored during times when electricity is plentiful and inexpensive (especially from intermittent power sources such as renewable electricity from wind power, tidal power and solar power) or when demand is low, and later returned to the grid when demand is high, and electricity prices tend to be higher.

As of 2020^[update], the largest form of grid energy storage is dammed hydroelectricity, with both conventional hydroelectric generation as well as pumped-storage hydroelectricity.^[1][2]

Developments in battery storage have enabled commercially viable projects to store energy during peak production and release during peak demand, and for use when production unexpectedly falls giving time for slower responding resources to be brought online. Green hydrogen, which is generated from electrolysis of water via electricity generated by renewables or relatively lower carbon emission sources, is a more economical means of long-term renewable energy storage in terms of capital expenditures than pumped-storage hydroelectricity or batteries.^[3][4]

Two alternatives to grid storage are the use of peaking power plants to fill in supply gaps and demand response to shift load to other times.