hydroelectric power plant

How to working hydroelectric power plant

Hydro-electric Power Station :

A generating station which utilizes the potential energy of water at a high level for the generation of electrical energy is known as a hydro-electric power station.

• Hydro-electric power stations are generally located in hilly areas where dams can be built conveniently and large water reservoirs can be obtained.

• In a hydro-electric power station, water head is created by constructing a dam across a river or lake. From the dam, water is led to a water turbine.

• The water turbine captures the energy in the falling water and changes the hydraulic energy into mechanical energy at the turbine shaft.

• The turbine drives the alternator which converts mechanical energy into electrical energy.

• They have the added importance for flood control, storage of water for irrigation and water for drinking purposes.

Advantages:

• It requires no fuel as water is used for the generation of electrical energy.

• It is quite neat and clean as no smoke or ash is produced.

• It requires very small running charges because water is the source of energy which is available free of cost.

• It is comparatively simple in construction and requires less maintenance.

• It does not require a long starting time like a steam power station. In fact, such plants can be put into service instantly.

• It is robust and has a longer life.

Disadvantages:

• It involves high capital cost due to construction of dam.

• There is uncertainty about the availability of huge amount of water due to dependence on weather conditions.

• Skilled and experienced hands are required to build the plant.

• It requires high cost of transmission lines as the plant is located in hilly areas which are quite away from the consumers.

Construction:

• Dam:

The dam is constructed across a river or lake and water from the catchment area collects at the back of the dam to form a reservoir.

• Pressure tunnel:

A pressure tunnel is taken off from the reservoir and water brought to the valve house at the start of the penstock.

• Surge tank:

A surge tank (open from top) is built just before the valve house and protects the penstock from bursting in case the turbine gates suddenly close due to electrical load being thrown off.

• Valve house:

The valve house contains main sluice valves and automatic isolating valves. The former controls the water flow to the power house and the latter cuts off supply of water when the penstock bursts.

• Penstock:

From the valve house, water is taken to water turbine through a huge steel pipe known as penstock.

• Turbine:

The water turbine converts hydraulic energy into mechanical energy. The turbine drives the alternator which converts mechanical energy into electrical energy.