- In hydroelectric power plants the potential energy of water is utilised to drive the turbine which in turn runs the generator to produce electricity.
- The basic requirement of hydroelectric power plant is a reservoir where large amount of water is stored during rainy season and used during other seasons.
- Therefore these types of power plants are located where the water resources are available in large quantity with high head.
- During the operation, the water is supplied to the turbine (prime mover) through the penstock which is located at much lower level than the height of water in the reservoir.
- Then, the water is impinged on the turbine blades which drives the turbine shaft to generate power.
- Figure shows the general layout of hydroelectric power plant.
- The function of various elements of hydroelectric power plant is as follows:
1. Reservoir
2. Dam
3. Trash rack
4. Gate
5. Penstock
6. Control Room
7. Turbine
8. Tail race
1. Reservoir
Reservoir used to store large amount of water during rainy season and supply water during other seasons. Water stored is not only used for power generation, but also for flood control, irrigation, water supply, navigation, etc. A reservoir may be natural or artificial.
2. Dam
Dam is a structure of considerable height built across the reservoir. It store water and it develops a reservoir to store water and it builds up a head for power generation.
3. Trash rack
It is provided for preventing the entry of debris (dust, dirt, etc.) from the dam, because any debris into the intake water pipe may damage the turbine blades or choke up the flow. It is generally made of steel.
4. Gate
It is provided to control the flow of water from reservoir to the turbine. According to the requirement, gate opening can be changed.
5. Penstock
It is a pipeline which carries water from reservoir to the turbine. Generally, to the withstand high pressures, it is made of concrete and of 1 to 2m in diameter.
6. Control Room
Control room or power house consists of turbine, generator and other electric equipment to convert mechanical energy of turbine into electrical energy.
7. Turbine
Turbine is used to convert kinetic energy of water into mechanical hydraulic energy. Generally used hydraulic turbine are Pelton turbine, Kaplan turbine, Francis turbine, etc.
8. Tail race
It is a path to lead the water discharged from the turbine to the river.
Advantages of hydroelectric power plant
- Water source is easily and readily available.
- No fuel is to be burnt to generate the power.
- The running cost of these power plants is very low as compared to thermal power plants.
- These power plants are more reliable.
- There is no problem of disposal of ash, emission of polluting gases and particulates.
- Life expectancy of these power plants is higher.
- Due to simple design and operation, these power plants do not require highly skilled operators. Manpower requirement is also low.
Disadvantages of hydroelectric power plant
- Power generation is dependent on the quantity of water available, which may vary from season to season.
- These power plants are located far away from the load centre which requires long transmission lines. The cost of these transmission lines and losses are more.
- The time required for the set-up of plant is more.
- Initial cost of set-up is very high.
FREQUENTLY ASKED QUESTIONS?
Q.1. Explain hydroelectric power plant?
Q.2. State advantages and disadvantages of hydro-power plant?