Hydropower is energy that comes from the force of moving water. The most common form of hydropower plant uses a dam on a river to store water in a reservoir. Enormous quantities of water are involved and a large hydro-electric power system requires a very large dam, or a series of dams.

Principle of hydropower generation:

Hydro-electric power is based on the simple principle of using falling water to spin a shaft connected to an electric generator. The greater the FALL of water, the more power it has to spin a shaft. The greater the quantity of water, the greater the number and size of the shafts that may be spun and the greater the electricity output.

Working of hydropower electricity plant:

A typical hydropower plant is a system with three parts:

• a power plant where the electricity is produced;
• a dam that can be opened or closed to control water flow; and
• a reservoir (artificial lake) where water can be stored

1. Water in a reservoir behind a hydropower dam flows through an intake screen, which filters out large debris, but allows fish to pass through.
2. The water travels through a large pipe, called a penstock.
3. The force of the water spins a turbine at a low speed, allowing fish to pass through unharmed.
4. Inside the generator, the shaft spins coils of copper wire inside a ring of magnets. This creates an electric field, producing electricity.
5. Electricity is sent to a switchyard, where a transformer increases the voltage, allowing it to travel through the electric grid.
6. Water flows out of the penstock into the downstream river