Pumped-Storage Hydropower (PSH)

Category: infrastructure

A grid-scale energy storage system configuration utilizing two water reservoirs at different elevations to balance fluctuating electrical demand.

PSH functions as a massive mechanical battery. During off-peak hours when power prices are low or solar arrays are clipping, excess grid electricity runs the system in reverse—pumping water from the lower pool up to the upper reservoir. During peak demand, the flow direction is inverted, dropping the water back down through reversible pump-turbines to generate high-value dispatchable power within minutes.

Common Examples

• The utility group expanded its portfolio with a new pumped-storage hydropower facility to absorb excess daytime generation from regional solar fields.
• Pumped-storage hydropower remains the dominant form of grid-scale energy storage, offering an average round-trip energy efficiency of seventy to eighty percent.