Pumped-storage hydroelectricity
Country Pumped storage capacity ( GW ) Total installed generating capacity ( GW ) Pumped storage/ total generating capacity
China 32.0 1646.0 1.9%
Japan 28.3 322.2 8.8%
United States 22.6 1074.0 2.1%
Spain 8.0 106.7 7.5%
Italy 7.1 117.0 6.1%
India 6.8 308.8 2.2%
Germany 6.5 204.1 3.2%
Switzerland 6.4 19.6 32.6%
France 5.8 129.3 4.5%
Austria 4.7 25.2 18.7%
South Korea 4.7 103.0 4.6%
Portugal 3.5 19.6 17.8%
Ukraine 3.1 56.9 5.4%
South Africa 2.9 47.3 6.1%
United Kingdom 2.8 94.6 3.0%
Australia 2.6 67.0 3.9%
Russia 2.2 263.5 0.8%
Poland 1.7 37.3 4.6%
Thailand 1.4 41.0 3.4%
Belgium 1.2 21.2 5.7%
Worldwide use
See also : United States Department of Energy Global Energy Storage Database Adam Beck Complex In 2010 the United States had 21.5 GW of pumped storage generating capacity ( 20.6% of world capacity ) . [ 24 ] PSH generated ( net ) −5.501 GWh of energy in 2010 in the US [ 25 ] because more energy is consumed in pumping than is generated . Nameplate pumped storage capacity had grown to 21.6 GW by 2014 , with pumped storage comprising 97% of grid-scale energy storage in the US . As of late 2014 , there were 51 active project proposals with a total of 39 GW of new nameplate capacity across all stages of the FERC licensing process for new pumped storage hydroelectric plants in the US , but no new plants were currently under construction in the US at the time . [ 26 ] [ 27 ] The five largest operational pumped-storage plants are listed below ( for a detailed list see List of pumped-storage hydroelectric power stations ) :
Pumped-storage hydroelectricity (PSH), or pumped hydroelectric energy storage (PHES), is a type of hydroelectric energy storage used by electric power systems for load balancing. The method stores energy in the form of gravitational potential energy of water, pumped from a lower elevation reservoir to a higher elevation. Low-cost surplus off-peak electric power is typically used to run the pumps. During periods of high electrical demand, the stored water is released through turbines to produce electric power. Although the losses of the pumping process makes the plant a net consumer of energy overall, the system increases revenue by selling more electricity during periods of peak demand, when electricity prices are highest. If the upper lake collects significant rainfall or is fed by a river then the plant may be a net energy producer in the manner of a traditional hydroelectric plant. Pumped-storage hydroelectricity allows energy from intermittent sources (such as solar, wind) and other renewables, or excess electricity from continuous base-load sources (such as coal or nuclear) to be saved for periods of higher demand. The reservoirs used with pumped storage are quite small when compared to conventional hydroelectric dams of similar power capacity, and generating periods are often less than half a day. Pumped storage is by far the largest-capacity form of grid energy storage available, and, as of 2017, the United States Department of Energy Global Energy Storage Database reports that PSH accounts for over 95% of all active tracked storage installations worldwide, with a total installed nameplate capacity of over 184 GW, of which about 25 GW are in the United States. The round-trip energy efficiency of PSH varies between 70%-80%, with some sources claiming up to 87%. The main disadvantage of PSH is the specialist nature of the site required, needing both geographical height and water availability. Suitable sites are therefore likely to be in hilly or mountainous regions, and potentially in areas of outstanding natural beauty, and therefore there are also social and ecological issues to overcome.