Electricity is critical to fuel the economic growth of India. The country is on the fast trajectory of development but to keep high momentum of growth availability of uninterrupted power supply is a must. India needs electricity to fuel the growth of every industry, be it manufacturing, healthcare or education. India is currently facing energy crisis with its major dependency on coal, crude oil imports to meet sharply growing energy needs of the country. With around 19% of India’s total population living without access to electricity, it continues to remain energy poor and India’s Prime Minister, Narendra Modi, has promised to strengthen India’s economy and improve the overall standard of living, with specific initiatives to create jobs and improve infrastructure, including ensuring universal access to electricity.
India has been a dominant player in global hydro power development and is the 7th largest producer of hydroelectric power in the world. India was one of the pioneering countries in establishing hydroelectric power plants. The power plants at Darjeeling and Shimsha (Shivanasamudra) were established in 1898 and 1902 respectively and are one of the first in Asia. As of 31 March, 2016, the utility scale installed capacity was 42,783 MW, which was 14.35% of total utility electricity generation capacity in India. In addition, small hydro power units with a cumulative capacity of 4,274 MW have been installed. Between 2014 and 2015, the total hydroelectric generation was 129 TWh. The hydroelectric power potential of India is estimated at 84,000 MW at 60% load factor, one of the largest in the world.
The hydroelectric power plant, also called as dam or hydropower plant, is used for generation of electricity from water on large scale basis. A high dam is built to create a reservoir, across the large river that has sufficient quantity of water throughout the river, and a station where the process of energy conversion to electricity takes place. In certain cases where the river is very large, more than one dam can built across the river at different locations.
To obtain the high head of water the reservoir of water should as high as possible and power generation unit should be as low as possible. The maximum height of reservoir of water is fixed by natural factors like the height of river bed, the amount of water and other environmental factors. The location of the power generation unit can be adjusted as per the total amount of power that is to be generated. Usually the power generation unit is constructed at levels lower than ground level so as to get the maximum head of water. The total flow rate of water can be adjusted through the penstock as per the requirements. If more power is to be generated more water can be allowed to flow through it.
Working Principle of Hydroelectric Power Plant
The water flowing in the river possesses two type of energy: the kinetic energy due to flow of water and potential energy due to the height of water. In hydroelectric power plants or dams potential energy of water is utilised to generate electricity. The potential energy of water due to its high location is converted into electrical energy.
The first step in the generation of energy in a hydropower plant is the collection of run-off of seasonal rain and snow in lakes, streams and rivers, during the hydrological cycle. The run-off flows to dams downstream. The water falls through a dam, into the hydropower plant and turns a large wheel called a turbine. The turbine converts the energy of falling water into mechanical energy to drive the generator. The total power generation capacity of the hydroelectric power plants depends on the head of water and volume of water flowing towards the water turbine. It is the most widely used form of renewable energy. Once a hydroelectric complex is constructed, the project produces no direct waste, and has a considerably lower output level of the greenhouse gas carbon dioxide (CO2) than fossil fuel powered energy plants. After this, process has taken place and electricity is transferred to the communities through transmission lines and the water is released back into the lakes, streams or rivers.
The entire process is not at all harmful as no pollutants are added to the water while it flows through the hydropower plant. Hydropower is called renewable source of energy because it uses and not consumes the water for generation of electricity and the hydropower leaves this vital resource available for other uses.
Cross section of a conventional hydroelectric dam
A typical Turbine and Generator
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