The diagram illustrates the process of generating electricity in a hydroelectric power station.
Overall, electricity is produced by utilizing the flow of water between a high-level reservoir and a low-level reservoir, with turbines generating power during the day and pumping water back up at night.
As shown in the first stage, water from a river is collected in the high-level reservoir. During the daytime, the intake gate opens, allowing water to flow downwards through a channel toward the reversible turbines. The rushing water causes the turbines to spin rapidly, which in turn drives the generator to produce electricity. This electricity is then transmitted to the national grid via power lines. After passing through the turbines, the water continues into the low-level reservoir.
In the second stage, during the night, the intake gate closes, and the turbines reverse their function. Water from the low-level reservoir is pumped back up to the high-level reservoir using the turbines, which now act as pumps. Although this process consumes energy and does not generate electricity, it restores the water to the upper reservoir, ensuring that the system can produce electricity again the following day.