Pumped Storage Hydroelectricity (PSH)

Pumped-storage hydroelectricity (PSH) (also referred to as pumped hydroelectric energy storage (PHES)), stores energy in the form of potential energy of water. It is used to store excess electricity generated or imported during low-demand periods, and the water is discharged during high demand periods. At efficiencies of minimum 70% to more than 80% over a pump cycle, it is the most common large-scale electrical energy storage system in commercial use.

Pumped-storage hydroelectricity is a primary element in the planned exploitation of renewable energy in the GIR (Green Industrial Revolution). A major drawback in wind power is its intermittency. By allowing a wind turbine to generate power at any time the wind is strong, the electricity can always be used to pump water to the elevated reservoir. This water can then be used when demand is highest, irrespective of wind conditions. this pump cycle system is available in all weather conditions, any season, and 24/7.

The DOE Global Energy Storage Database estimates that total capacity of PSH worldwide exceeds 168 GW.

The effective efficiency is 65-70%: about 1.4 kWh generated by a wind turbine and stored in a pumped storage reservoir will generate 1.0 kWh when needed later. A hydraulic turbine generator has a high efficiency (more than 95%), and water pumps are less efficient.

Capital costs are likely to be in line with those for a conventional project, i.e. between $1000/kW and $3000/kW.