The chief advantage of hydro systems is elimination of the cost of fuel. Hydroelectric plants are immune to price increases for fossil fuels such as oil, natural gas or coal, and do not require imported fuel.
Hydroelectric plants tend to have longer lives than fuel-fired generation, with some plants now in service having been built 50 to 100 years ago.
Labour cost also tends to be low since plants are generally heavily automated and have few personnel on site during normal operation.
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Hydroelectric plants generally have small to negligible emissions of carbon dioxide and methane due to reservoir emissions, and emit no sulphur dioxide, nitrogen oxides, dust, or other pollutants associated with combustion.
Since the generating units can be started and stopped quickly, they can follow system loads efficiently, and may be able to reshape water flows to more closely match daily and seasonal system energy demands.
Hydroelectric plants with reliable hydrological histories are dispatchable and can be considered firm capacity. Consequently, in normal water years hydroelectric plants designed for a firm load will have a useful amount of surplus energy that may be exportable if transmission is available.
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Pumped storage plants currently provide the most significant means of storage of energy on a scale useful for a utility, allowing low-value generation in off-peak times (which occurs because fossil-fuel plants cannot be entirely shut down on a daily basis) to be used to store water that can be released during high load daily peaks. Operation of pumped-storage plants improves the daily load factor of the generation system.
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Reservoirs created by hydroelectric schemes often provide excellent leisure facilities for water sports, and become tourist attractions in themselves.
Multi-use dams installed for irrigation, flood control, or recreation, may have a hydroelectric plant added with relatively low construction cost, providing a useful revenue stream to offset the cost of dam operation.
Hydro power plants convert about 90 percent of the energy in falling water into electrical energy. This is much more efficient than fossil-fueled power plants, which lose more than half of the energy content of their fuel as waste heat and gases.
Hydro generates few GHG and no other air pollutants.
Wildlife preserves can be created around reservoirs, which can provide stable habitats for endangered and threatened species(Eg. catch rates for game fish like walleye and small mouth bass are substantially higher on hydro power reservoirs than natural lakes.)
- Flood prevention
- Humidity and temperature increase, which is beneficial to crops(Eg.Three Gorge Dam in China)
Though,as usual,there is a anti-opinion about ,whether hydropower a less Green House Gas emitter than a Fossil Fueled power house.According to Dr.Fearnside,GHG emitted from hydro power terms are greater than fossil fuel plants.He explain this with the help of CO2 compressed in CocoCola .When you open a bottle of CocoCola,a lot of CO2 is emitted due to the sudden reduction of pressure.Similarly when water comes out of the spillways and turbine,pressure is reduced and hence a lot of methane is released . As 1 ton of CO2 is equivalent to 21 tons of CO2,hence the GHG emission from the hydro power plants are worth noticiable.You can read the full article about "Why Hydropower is Not Clean Energy" by Dr. Philip M. Fearnside
But though there is a debate about whether hydro power's ability to be a clean energy or not,its potential of becoming the most efficient alternative energy source is never doubted nor contested.
Thanks
Mrinmoy
Research Scholar
School of Water Resources Engg,Jadavpur University
http://www.baipatra.ws
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