Hydroelectricity

Hydroelectricity is the term referring to electricity generated by hydropower; the production of electrical power through the use of the gravitational force of falling or flowing water. It is the most widely used form of renewable energy. Hydropower is produced in 150 countries, with the Asia-Pacific region generating 32 percent of global hydropower in 2010. China is the largest hydroelectricity producer, with 721 terawatt-hours of production in 2010, representing around 17 percent of domestic electricity use. There are now three hydroelectricity plants larger than 10 GW: the Three Gorges Dam in China, Itaipu Dam across the Brazil/Paraguay border, and Guri  Dam in Venezuela.

Ten of the largest hydroelectric producers as at 2009.
Country	Annual hydroelectric production (TWh)	Installed capacity (GW)	Capacity factor	% of total capacity
China	652.05	196.79	0.37	22.25
Canada	369.5	88.974	0.59	61.12
Brazil	363.8	69.080	0.56	85.56
United States	250.6	79.511	0.42	5.74
Russia	167.0	45.000	0.42	17.64
Norway	140.5	27.528	0.49	98.25
India	115.6	33.600	0.43	15.80
Venezuela	85.96	14.622	0.67	69.20
Japan	69.2	27.229	0.37	7.21
Sweden	65.5	16.209	0.46	44.34

Hydroelectric power for the Nation

•  China is the largest hydroelectricity power producer and Canada is the largest producer of hydroelectricity in the world

• Turkey is producing least units of electricity with hydroelectricity power plant.

Hydroelectricity in india

With more than 70% of the electricity requirement in India being contributed from thermal sources And various issues and problems such as peaking shortage, low PLF operation of many thermal generating stations etc., there is an urgent need to review the prevailing energy mix. Hydropower potential is abundantly available to the tune of about 148,700 MW and more

Than 75% of which remaining untapped and with all the inherent advantages associated with

hydropower, the energy mix can be improved by the development of the balance huge potential As per the Central Electricity Authority (CEA) estimates, India would require an addition of at least 161 Giga Watt of generation capacity by the year 2016-􀂶17 over the existing generation capacity. Out of total hydro potential of 84,044 MW at 60% load factor from 845 schemes with a total installed capacity of nearly 148,700 MW, less than 25% hydro potential has been exploited so far and balance 75% hydro potential remains untapped. It thus comes out that bulk of the future requirement of the electric power can be met by the hydropower development

HYDROPOWER DEVELOPMENT  POTENTIAL

India is blessed with huge amount of hydropower potential major amount of which still remain untapped. In terms of hydropower potential, India ranks fifth in terms of exploitable hydro potential on global scenario.

Hydropower potential of the country has been assessed by Central Electricity Authority (CEA) in1987 as 84044 MW from 845 schemes with a total installed capacity of about 148,700 MW. Besides 56 sites for pumped storage scheme with a total installed capacity of about 93,920 MW have also been identified in various regions of the country. In addition to potential of medium and major hydro schemes 1512 small hydroelectric schemes having aggregate installed capacity of 6782 MW on canal falls/rivers have also been identified.

Hydro potential developed so far is only about 23 percent of the total assessed potential and

another about 6.5 percent is in various stages of development, thus about 70 percent of the hydro potential still remains to be developed. Share of hydropower which was about 37 percent at the time of independence in the year 1947 continued to rise till 1963 when achieved a figure of about 50 percent. Thereafter, the share of hydropower has been continuously declining and at present it is only about 23 percent of the total installed capacity of the country. The ideal hydrothermal ratio for Indian power system has been assessed as 40:60 for reliability of system operation. The present ratio is about 23:67 which needs to be augmented to meet peak load requirements as well as to improve system reliability. Out of 845 schemes identified by CEA (Central Electricity Authority) in reassessment studies, at

present , 288 hydro schemes with an aggregate installed capacity of about 42000 MW are either under operation/implementation. The balance schemes include about 164 schemes each of which having installed capacity of 25 MW or less of total capacity of 2300 MW. Thus about 400schemes having total likely installed capacity of above 1,00,000 MW are yet to be taken up for development. Similarly share of Hydro Power in installed capacity which rose to 50.62% in the year 1963, experienced a steep fall, and at present it is only just over 23% of the total capacity which is required to be enhanced to at least 40% (though there is no upper limit) so as to achieve hydro/thermal mix of 40: 60 leading to better system availability and reliability.

HYDROPOWER AND ENVIRONMENT

Hydropower is nonpolluting, but does have environmental impacts

Hydropower does not pollute the water or the air. However, hydropower facilities can have large environmental impacts by changing the environment and affecting land use, homes, and natural habitats in the dam area.

Most hydroelectric power plants have a dam and a reservoir. These structures may obstruct fish migration and affect their populations. Operating a hydroelectric power plant may also change the water temperature and the river's flow. These changes may harm native plants and animals in the river and on land. Reservoirs may cover people's homes, important natural areas, agricultural land, and archeological sites. So building dams can require relocating people. Methane, a strong greenhouse gas, may also form in some reservoirs and be emitted to the atmosphere.

Region wise contribution of Hydropower

REGION	PERCENTAGE
NORTH	30.34
WEST	13.86
SOUTH	37.2
EAST	15.27
NORTH-EAST	37.72
INDIA	24.74

HOW DO HYDROELECTRICITY POWER PLANT WORK?

There are four parts of atypical hydropower plant which collectively helps in generating electricity from moving water. These are DAMS, TURBINES, GENERATORS AND ROTOR & STATOR. First one is the dam. The dam is made on a river to collect water. It serves as a water reservior as whenever it rains, the water gets collected in the dam. The potential energy required for further work is generated by the water level difference between dams and the turbines which is very high(about 100 feets). Dams Also control the water flow through penstocks. The next step in the process is conversion of the kinectic energy of water into mechanical energy. The water flows from a hieight throw the channeled vessels known as PENSTOCKS to the turbines which have blades. The water falls at a speed of one gallon per second and has enough linetic energy that when they strike hard with the blades of the turbines, they start spinning which means that the kinetic energy is converted into mechanical energy.the turbines is resembled a lot by the windmills where the energy is created through wind instead of water. But the turbines use potential and mechanical energy of falling water to convert into work. Next is generators. After converting the kinergy into mechanical energy the shafts of the turbines convert the mechanical energy into elctric energy. Basically, the generators works on the principle of magnets which is that when you pass a magnet near a conductor, electric current flows through it. The rotor having pole rotates on a specific speed. When it rotates it passes the field poles across the stator to make sure that it has the same effect of electric field. The water should keep on moving constantly to make sure that the amount of electricity produced is great. Static water cannot genearte electricity. The electricity via power lines is transferred to substation which provides it to the consumers.

So, the process is of great importance. It should be performed properly and in a right manner so that maximum amount of electricity can be produced. This process is not much costly since it does not lead to any fuel production and not much health hazardous chemicals are produced by it. But the research is still going on.