How it works: as long as the water is flowing fast enough and in great enough volume, it can turn generators that produce electricity.
How much supply: at present, about 780 gigawatts of power are produced by hydro power worldwide. This is about 20% of all the world's energy. At least 100 GW more are under construction.
- It's not available everywhere.
- It causes some amount of environmental degradation because it needs dams. The dams flood areas behind them and they can kill fish, which can be a big problem for areas where fish are an important resource.
How much supply
Planning of the hydropower full potential could avoid emissions of pollutants of the power system, in addition to those already avoided by setting in the function,
annually representing approximately: ~ 25 million tonnes of CO2, ~ 0.45 million tons SO2, ~ 135,000 t NOx, ~ 6000 t powder, ~ 0.37 million ton CO, ~ 30 × 106 tons of slag deposits and ash emissions related to fuel local mining industry.
Potential foreign exchange savings by reducing imports of fossil fuels could reach about 2000 million U.S. $ / year.
Problems with hydroenergy
Unfortunately, the growth rates of the planned hydropower sector in perspective energy system development are almost 3 times lower than those of assembly and over 2 times lower than the thermal power sector until 2005.
Effects on the natural environment, sometimes unfortunate (ecosystems changes in lakes accumulation, employment of land, reducing flows on the river downstream of the dam, biotope changes, deployment of habitats and disturbance of ecosystems) may be sensitive improved by appropriate measures, the costs (reduced flow in the river downstream of dam, changing biotopes, deployment of habitats and disturbance of ecosystems) can be significantly improved by appropriate measures, with corresponding costs. They are in good extent offset by beneficial environmental effects: the development of aquatic ecosystems of the lake
valuable and stable, the occurrence of valuable habitat for migratory waterfowl, improve conditions for some terrestrial species, a major potential extension of water ecosystems
by fishing and guiding their evolution.
What is hydro energy has been made clear enough in previous two answers. So I will now write about how hydro power is generated, and some problem with hydro energy.
Hydro power is generated by directing water flowing with high speed, or under great pressure, or a combination to the inlet of a water turbine. This flow of water makes the water turbine rotate with great force and speed, converting the kinetic energy water velocity, and potential energy of water pressure in to mechanical energy delivered to the shaft of the turbine. The turbine shaft is directly coupled to a generator. The mechanical energy produced by the turbine is thus used to drive the generator which produces electrical power.
The water for generation of hydro-power is provided by rivers, which flow from places of high altitudes to places of low altitude. In this way the river water possesses potential energy that gets converted to kinetic energy as it flows down its course. To use maximum of the the potential energy of water that it possesses while it is at higher altitudes, the water may be directed from high altitudes to power generating stations located at much lower altitudes through artificially built ducts. Also the river water may be collected at higher altitudes in dams so that it can be used for generation of energy as required, rather than depending on natural inflow of water.
Cost of all these facilities increases the cost of construction of hydro power station much more than that of thermal power station of comparable generating capacity. However operating power of hydro power stations is less than that of thermal power station.
In spite of the heavy investment in constructing dams, it is usually not economically possible to make hydro power station that generate electric power at full capacity round the year. Therefore, capacity of hydro-power station is more likely to be used to meet additional peak requirements of power rather than the stable base requirements, 24 hours a day.
Apart form high capital cost and dependence on fluctuating and some times uncertain water flow, the major disadvantage of hydro power is that the such power stations have to be located where the water is available rather than where the electricity is required. Also the potential of generating hydro power by way of availability of water resources is limited as compared to availability of coal for thermal power stations.
Hydro stands for water. Flowing water and falling water possess the energy.In nature the rivers and falls have lot of energy which could be harnessed for the use. Electricity is the best energy that could easily be generated from this energy source of the nature. Making the tubines rotate with this energy, the mechanical energy of the moving or falling water is converted into the electrical energy which is best and fastest portable and ost flexible. Compared to the costof generation of nulear or thermal energy, the generation of hydro energy is easier, more economic and less environment hazrdous. It does not affect the quality of water.