The diagram below shows how electricity is generated in a hydroelectric power station.
Summarise the information by selecting and reporting the main features, and make comparisons where relevant.
Hydroelectric power station
Sample Essay
The diagram displays how a hydroelectric power plant produces electricity.
Overall, the production of hydroelectricity is cyclical and consists of four main parts: storing water high, letting water flow downhill to generate electricity, storing water low, and pumping water back uphill for reuse.
First of all, the dam stores river water behind it in the upper reservoir that has an intake at the bottom. During the day, the intake is open, allowing water to flow through. As the water moves downhill into the lower reservoir, it passes through the turbines and turns their blades to generate mechanical energy. The spinning turbines then drive the generator to convert the mechanical power into electricity, which is subsequently delivered to the national grid through power lines.
During the night when demand for electricity is low, the turbines act as pumps that pump water kept in the lower reservoir back to the upper reservoir for reuse.
