The diagram illustrates how a hydroelectric power station generates electricity. Overall, the process involves a 2 step procedures which include; the downward flow of water from the high-level reservoir to power station during the day, and a reverse upward flow of water through the power station from the low-level resevoir at night.
As presented, the production of light is done during the day. The procedure starts from the flow of water from the river into a high-level reservior which is just beside a dam. During the day, the dam opens and allows the water to flow downward towards the power station. Afterwards, the water passes through the power station through a reversibe turbines and flows into a low-level reservoir. The flow of water through the reversible turbines helps the operation of the generator. On the other hand, the generator through this process generates electricity, and releases the energy through the power lines, which in turn deposits it into a bational grid.
In contrast, the whole process at night is a direct reverse of the day process. It starts from the low-level reservoir. The water that had flowed into and stored inside the low-level reservoir are being pumped out by the reversible turbines. The reversible turbines pumps the water upwards towards the dam. However, the dam is always closed at night, thereby inhibiting the passage of water into the high-level reservoir.