Pumped storage systems are based on the principle of pumping water from a low elevation reservoir to a high elevation reservoir using low-cost, off-peak electric power (when electricity prices are low).  The water is then released through turbines during periods of high electrical demand (when electricity prices are high), thereby increasing revenue.  Reversible pump-turbine assemblies act as both pump and turbine in these systems.

HTE Engineering and its partners designed the Ningbo Pumped Storage Power Station, the first medium pumped storage station in China, with an installed capacity of 2×40 MW.