Pump storage power plant – sophisticated engineering complex with two reservoirs, which  are situated at different elevations.

During off  peak  periods,  power  in  taken  from the lower reservoir (reservoir of Kaunas hydroelectric plant on river Nemunas)  to the upper  one (artificial reservoir).

In peak load periods or in case of emergency, the water stored in the upper reservoir is used to drive turbine generator units and supply  power to electricity network.