A power generation station which uses the potential or kinetic energy of water for the
generation of an electrical energy is called hydro -electric power station.
Water has a kinetic energy when it is in motion. While the water stored at high level has a
potential energy. The difference in level of water between the two points is called head. Such a
water head is practically created by constructing reservoirs across river or lake. Generally a dam
is constructed at high altitudes, which can be used as a continuous source of the water for the
hydro-electric power stations. The water from the dam is taken through pipes and canals to the
water turbine, which is at lower level. The turbine obtains the energy from the falling water and
changes it into a mechanical energy. This mechanical energy of the turbine is then used to drive
the alternator, which converts the mechanical energy into an electrical energy.
Factors for Selection of Site
The water reservoir like dam cannot be constructed anywhere. There are number of factors
of affecting the choice of site for the hydroelectric power station.
- Availability of water: As the basic requirement of hydro -electric plant is the water, the
availability of huge quantity of water is the main consideration. The plant must be constructed
where sufficient quantity of water is available at a good head. The previous rainfall records are
studied and the maximum and minimum quantity of water available during the year estimated.
Considering the losses such as evaporation, the water necessary for the plant is calculated. Then
by comparing both the estimations, the choice of the site is done.
- Storage of water : The rainfall is not consistent every year. Hence the available water should
be stored. This makes necessary to construct dams. The storage helps in equalizing the flow of
water throughout the year. So site should be provide sufficient facilities for erecting dam and the
storage of water.
- Head of water : For getting sufficient head, the dam or reservoir should be constructed at a
height in a hilly area. The availability of the head directly affects the cost and economy of the
power generation. So site should be selected in proper geographical area, which can give
sufficient water head.
- Cost and type of land: The initial cost of the project includes the cost of the land. Hence land
must be available at a reasonable price. Similarly the type of the land must be such that it should
able to withstand the weight of the heavy equipment to be installed.
- Transportation facilities: For transporting the equipment and the machinery, the site selected
must be easily accessible by rail and road.
- Distance from load centers: The load center is connected to the site by the transmission lines.
Hence to keep the cost of the transmission lines minimum and the losses occurring in the line
minimum, the distance of the site from the load centers must be less. Otherwise the overall cost
All these factors affect the selection of site for the hydro-electric power station.