During periods of low energy demand on the electricity network, surplus electricity is used to pump water to the higher reservoir. When electricity demand increases, the stored water is released, generating electricity. Pumped storage hydro (PSH) must have a central role within the future net zero grid.
A dynamic energy storage solution, pumped storage hydro has helped ‘balance’ the electricity grid for more than five decades to match our fluctuating demand for energy. Pumped storage hydro (PSH) involves two reservoirs at different elevations.
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. A PSH system stores energy in the form of gravitational potential energy of water, pumped from a lower elevation reservoir to a higher elevation.
With closed-loop PSH, reservoirs are not connected to an outside body of water. Open-loop pumped storage hydropower systems connect a reservoir to a naturally flowing water feature via a tunnel, using a turbine/pump and generator/motor to move water and create electricity.
The case study of the 300 MW Balakot conventional hydropower plant in Khyber Pakhtunkhwa, Pakistan indicates that the pumped storage hydropower sites, where additional water streams reach the upper storage reservoir, can reduce pumping energy consumption by up to 166 GWh/year.
Results indicate that pumped hydro storage can keep the diesel contribution to less than 10% to meet the demand, whereas this number can go up to more than 50% for conventional systems where the streamflow potential is limited compared to the demand.