As most people know, the production and consumption of electricity do not always match. Both in industrial and developing countries with a rising need for energy, there are daily fluctuations in the electricity grid. In the future, as power generation by wind and PV increases, electricity generation will at times be far above the load (in case of strong wind and high solar radiation) and, likewise, far below the load (in case of weak wind and low solar radiation) in an increasing number of hours. In addition, it must be expected that upward and downward jumps of renewable generation will be rising, especially in the short-term time frame (cloud movements, wind fronts and calms, etc), which will be difficult to predict accurately. Pumped storage power plants are ideally suited to help even out these frequent changes between electricity shortages and surpluses, thus could significantly prevent the curtailment of renewable generation.
The principle behind pumped storage is both simple and ingenious at the same time. Pumped storage power plants are an energy storage system and a hydroelectric power plant in one. If there is surplus power on the grid, the pumped storage power station switches to pumping mode: an electric motor drives pump turbines, which pump water from a lower reservoir to a higher storage basin. If the demand for electricity in the grid rises, water is released from the upper basin via a pressure pipeline to the bottom. The water causes the pump turbines to move, which now operate in turbine mode and are used in turn to drive the generators. Within seconds, electricity is generated and fed back into the electricity grid.
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