Flowing water possesses kinetic energy. The energy of flowing water has been traditionally used for rotating the water wheels and drive- water mills to grind wheat to make flour. The traditional use of energy of flowing water has been modified by improvements in technology and use to generate electricity.
This is done by establishing hydro-power plants. At hydro- power plants, the energy of filling water (or flowing water) is tapped by using a 'water turbine' and then made to drive generators. We will now describe a hydro- plant in detail.
Hydro- Power Plant (or Hydroelectric Power Plant)
" A power plants that produces electricity by using flowing water to rotate a turbine (which drives the generator), is called hydro- power plant (or Hydroelectric plant)".
The electricity produced by using the energy of falling water (or flowing water) is called Hydroelectricity. A hydro- power plants produces electricity as follows:
Rain falling on the high ground in hilly areas flows as rivers. In order to produce electricity, a high- rise dam is built to stop the following river water. Due to this, a large lake or reservoir builds up behind the dam. As more and more water collects in the reservoir, the water is converted into the potential energy of water stored behind the dam. Thus, the water stored behind a tall dam has a lot of potential energy (due to its great height).
The sluice gates (sliding gates) at half the height of dam are opened to allow some of the stored water to escape. This water is taken through pipe to the turbine installed at the bottom of the dam. Since the water falls down through a large height from the dam, it flows very fast (it's potential energy is changed into kinetic energy).
A high pressure jet of fast flowing water pushes on the blades of turbine its shaft. When the turbine rotates, its shaft also rotates and drives the generator. The generator produces electricity.
When the Hydroelectric generator works and produces electricity, water flows out of the dam continuously and the level of water in the reservoir falls slowly. The reservoir is filled up again by the rain water brought in by the rivers. Please notes that since water in the dam reservoir needed for generating electricity is refilled each time it rains, therefore, Hydroelectric Power is a reservoir source of energy.
It will never get exhausted. Another point to be noted is that water to the turbine is taken from a point midway up the dam, so that the generator continue to work even if the water level in the reservoir falls below normal.
A hydro- power plants converts the potential of water stored in the reservoir of tall dam into electric energy. The dams for generating Hydroelectric can be built only in a limited number of places, usally in the hilly areas or at the foothill (where the water can fall from a considered height). At present, of the total electric power generator in our country, almost one- fourth is contribute by Hydroelectricity.
Advantage of Generating Hydroelectricity
The advantage of using the energy of flowing water for the generator of electricity are the following:
* The generation of electricity from flowing water does not produce any environmental pollution.
* Flowing water is a renewal sources of electric energy which will never get exhausted.
* The construction of dam on rivers helps in controlling floods, and in irrigation.
Disadvantage of Generating Hydroelectricity
The production of hydroelectric power by constructing high- rise dams on river has certain problems associated with it. Some of these are given below:
* Large areas of agricultural land, a vast variety of flora and fauna (plants and animals) as well as human settlement (or villages) get submerged in the water of reservoir formed by the dam. Due to this many plants and trees are destroyed animals get killed and many people are rendered homeless. This creates the problem of satisfactory rehabilitation of the people display from the dam site.
* Due to the construction of dam on river, the fish 🐠 in the downstream area do not get sufficient nutrients materials due to which the production of fish decreases repidly (because the fish nutrients remains trapped in the reservoir formed by the dam.
* The vegetarian which is submerged under water at dam site rots under anaerobic conditions and produces a large amount of methane which is a greenhouse gas (and hence harmful for the environment).
The opposition to the construction of Tehri Dam on the river Ganga and. Sardar Sarover Project on the river Narmada are due such problems. So, before taking a decision of generate Hydroelectricity by constructing high - rise dams on rivers , it is necessary to consider it's long term effects on the environment and social life carefully.
The energy of flowing water is called Hydroenergy. This energy water (or Hydroenergy) is in fact an indirect source of solar energy. This because it is the solar energy recirculates water in nature in the form of water- cycle. It is this water which then flows in the rivers and makes water- energy available to us.
