Pumped storage projects store and generate energy by moving water between two reservoirs at different elevations. At times of low electricity demand, like at night or on weekends, excess energy is used to pump water to an upper reservoir.
Pumped hydro storage works by using excess energy to pump water from a lower reservoir to a higher one, where it is stored as potential energy. Then, when the energy is needed, the water is released from the upper reservoir and flows through a turbine, generating electricity. The basic process can be broken down into four main steps:
The basic operating principle is similar for all of them: water flows through a turbine to generate electricity. However, unlike run-of-river or reservoir power plants, pumped storage plants enable us to store and schedule hydroelectric power generation, while also playing a crucial role in stabilizing the power grid.
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.
This means that not all of the energy put into the system can be retrieved as electricity, which can reduce the overall efficiency of the system. There are several notable examples of pumped hydro storage projects around the world, including: Dinorwig Power Station is a pumped hydro storage facility located in Wales, UK.
Pumped storage hydropower plants play a key role in the future of energy, contributing to grid stabilization, renewable energy storage and reduced dependence on fossil fuels. Together with BESS systems, renewable energy storage in pumped storage power plants will be a strategic ally for a resilient, secure and sustainable energy system.