EXPLANATION:
FUNCTIONING OF HYDRO POWER PLANT:
Hydroelectricity is produced in a hydroelectric power plant. In this plant, the water is released from a high location. The potential energy present in the water is converted into kinetic energy, which is then used to rotate the blades of a turbine. The turbine is hooked to the generator which produces electricity.
COMPONENTS:
RESERVOIR: The basic requirement of a hydro electric power plant is a good reservoir where large quantity of water is stored during flood season and used during dry season.
DAM: Most hydropower plants rely on a dam that holds back water, creating a large reservoir. Often, this reservoir is used as a recreational lake, such as Lake Roosevelt at the Grand Coulee Dam in Washington State.
PENSTOCK: A pipe between the surge tank and the power house is known as pen stock. A pen stock is a conductor that takes water from the reservoir to the power house. Usually steel, RCC pipes are used. Penstocks are usually equipped with head gates at the inlet which can be closed during the repair of penstocks.
INTAKE: Gates on the dam open and gravity pulls the water through the penstock, a pipeline that leads to the turbine. Water builds up pressure as it flows through this pipe.
TURBINE: The water strikes and turns the large blades of a turbine, which is attached to a generator above it by way of a shaft. The most common type of turbine for hydropower plants is the Francis Turbine, which looks like a big disc with curved blades. A turbine can weigh as much as 172 tons and turn at a rate of 90 revolutions per minute (rpm), according to the Foundation for Water & Energy Education (FWEE).
POWER HOUSE: A power house houses the turbine and the generator. The turbine rotates the turbine shaft which in turn rotates the generator shaft, which is coupled to the turbine shaft. Thus the turbine converts hydraulic energy into mechanical energy and the generator converts mechanical energy into electrical energy. The power house is usually at the foot of the dam.
GENERATORS: As the turbine blades turn, so do a series of magnets inside the generator. Giant magnets rotate past copper coils, producing alternating current (AC) by moving electrons.
TRANSFORMER: The transformer inside the powerhouse takes the AC and converts it to higher-voltage current.
POWER LINES: Out of every power plant come four wires: the three phases of power being produced simultaneously plus a neutral or ground common to all three.
OUTFLOW: Used water is carried through pipelines, called tailraces, and re-enters the river downstream.
SURGE TANK: Surge tank is a small additional storage facility near the power house. It is required when there is considerable distance between the power house and the reservoir. When the distance is more non-uniform water intake to the power house results in the bursting of penstocks. In the absence of surge tank, the excess water rushes at the lower end causing the penstock to burst. However in the presence of a surge tank and can be used whenever there is any water shortage. Thus the surge tank acts as a shock absorber or a pressure regulator tank.
TYPES OF HYDRO POWER PLANT:
1. Impoundment: An impoundment facility, typically a large hydropower system, uses a dam to store river water in a reservoir. The water may be released either to meet changing electricity needs or to maintain a constant reservoir level.
2. Diversion: A diversion, sometimes called run-of-river, facility channels a portion of a river through a canal or penstock. It may not require the use of a dam.
3. Pumped Storage: When the demand for electricity is low, a pumped storage facility stores energy by pumping water from a lower reservoir to an upper reservoir. During periods of high electrical demand, the water is released back to the lower reservoir to generate electricity.
Sizes of Hydro power Plants:
Facilities range in size from large power plants that supply many consumers with electricity to small and micro plants that individuals operate for their own energy needs or to sell power to utilities.
1. Large Hydro power plant: Although definitions vary, DOE defines large hydropower as facilities that have a capacity of more than 30 megawatts.
2. Small Hydro power plant: Although definitions vary, DOE defines small hydropower as facilities that have a capacity of 0.1 to 30 megawatts.
3. Micro Hydro power plant: A micro hydropower plant has a capacity of up to 100 kilowatts (0.1 megawatts).
ADVANTAGES:
1. Once a dam is constructed, electricity can be produced at a constant rate.
2. If electricity is not needed, the sluice gates can be shut, stopping electricity generation. The water can be saved for use another time when electricity demand is high.
3. Dams are designed to last many decades and so can contribute to the generation of electricity for many years / decades.
4. The lake that forms behind the dam can be used for water sports and leisure / pleasure activities. Often large dams become tourist attractions in their own right.
5. The lake's water can be used for irrigation purposes.
6. The build up of water in the lake means that energy can be stored until needed, when the water is released to produce electricity.
7. When in use, electricity produced by dam systems do not produce green house gases. They do not pollute the atmosphere.
DISADVANTAGES:
1. Dams are extremely expensive to build and must be built to a very high standard.
2. The high cost of dam construction means that they must operate for many decades to become profitable.
3. The flooding of large areas of land means that the natural environment is destroyed.
4. People living in villages and towns that are in the valley to be flooded, must move out. This means that they lose their farms and businesses. In some countries, people are forcibly removed so that hydro-power schemes can go ahead.
5. The building of large dams can cause serious geological damage. For example, the building of the Hoover Dam in the USA triggered a number of earth quakes and has depressed the earth’s surface at its location.
6. Although modern planning and design of dams is good, in the past old dams have been known to be breached (the dam gives under the weight of water in the lake). This has led to deaths and flooding.
7. Dams built blocking the progress of a river in one country usually means that the water supply from the same river in the following country is out of their control. This can lead to serious problems between neighbouring countries.
8. Building a large dam alters the natural water table level. For example, the building of the Aswan Dam in Egypt has altered the level of the water table. This is slowly leading to damage of many of its ancient monuments as salts and destructive minerals are deposited in the stone work from ‘rising damp’ caused by the changing water table level.
SITE SELECTION PARAMETERS:
1) Availability of Water
Since the primary requirement for a hydro electric power station, is the availability of huge amount of water such plants should be built at a place (e.g. River, canal) where adequate water is available at a good head.
2) Storage of Water
There are wide variations in water supply from a river or canal during the year. This makes its necessary to store water by constructing a dam in order to ensure the generation of power through out the year. The storage helps in equalizing the flow of water so that any excess quantity of water at a certain period of the year can be made available during times of very low flow in the river. This leads to the conclusion that site selected for hydro electric plant should provide adequate facilities for erecting a dam and storage of water.
3) Cost and Type of Land
The land for the construction of plant should be available at a reasonable price. Further, the bearing capacity of the soil should be adequate to withstand the installation of heavy equipment.
4) Transportation Facilities
The site selected for the hydro-electric plant should be accessible by rail and road so that necessary equipment and machinery could be easily transported.
It is clear from the above mentioned factors that ideal choice of site for such a plant is near a river in hilly areas where dam can be conveniently built and large reservoirs can be obtained.
STATUS OF HYDRO POWER PLANT:
Sr. no.
|
Power Plant
|
State
|
Commissioned Capacity (MW)
|
year of commission
|
1
|
Baira siul
|
Himachal Pradesh
|
180
|
1981
|
2
|
Loktak
|
Manipur
|
105
|
1983
|
3
|
Salal-I
|
Jammu & Kashmir
|
345
|
1987
|
4
|
Tanakpur
|
Uttarakhand
|
120
|
1992
|
5
|
Chamera-I
|
Himachal Pradesh
|
540
|
1994
|
6
|
Salal-II
|
Jammu & Kashmir
|
345
|
1996
|
7
|
Uri-I
|
Jammu & Kashmir
|
480
|
1997
|
8
|
Rangit
|
Sikkim
|
60
|
1999
|
9
|
Chamera-II
|
Himachal Pradesh
|
300
|
2004
|
10
|
Indira Sagar
|
Madhya Pradesh
|
1000
|
2005
|
11
|
Dhauliganga-I
|
Uttarakhand
|
280
|
2005
|
12
|
Dul Hasti
|
Jammu & Kashmir
|
390
|
2007
|
13
|
Omkareshwar
|
Madhya Pradesh
|
520
|
2007
|
14
|
Teesta-V
|
Sikkim
|
510
|
2008
|
CONCLUSION:
After studding hydro power plant we conclude that hydro power plant is easy way to produce electricity. In hydro power plant installation cost is high, but after it constructs its maintenance cost is low. It can easy to start & easy to stop. If water is available for whole year then it is very efficient power plant.
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