Hydroelectricity: Clean Energy from Flowing Water
Water is at present the leading renewable energy source used by electric utilities to generate electric power. Currently there are numerous hydro-electric power stations, providing around 20% of the world’s electricity. The name “”hydro”” comes from the Greek word for water. The water cycle of evaporating from the heat of the sun and falling back to earth is continuous, thus hydropower is considered a renewable energy resource.
Hydropower facilities intercept the water on its descending path, converting its mechanical energy into electricity. Hydroelectric power plants operate where suitable waterways are available; many of the best of these sites have already been developed. Generating electricity using water has several advantages. Besides being a source of cheap power it has an advantage of no fuel combustion, there is negligible air pollution in comparison with fossil fuel power plants and limited thermal pollution compared to nuclear plants.
How it works
A dam is built to trap water, generally in a valley where there is an existing lake. Water flows through tunnels in the dam turning the turbines and thus powers the generator. The dams are designed much thicker at the bottom than at the top, because the pressure of the water increases with depth. The water above the dam stores gravitational potential energy. The water arrives at the turbines with high pressure because of the height of the dam. This means we can extract a great deal of energy from it. The water then flows away down the river as normal.
Hydro power stations dams are very expensive to build, however once the station is built, the water comes free of charge, and there is no waste or pollution. Hydro power stations can produce a great deal of power at an economical rate.
The potential energy stored in dammed water, drives a water turbine and generator. The energy extracted from the water depends on the quantity and on the difference in height between the source and the water’s outflow. This height difference is called the head and this is proportional the amount of potential energy in water.
The water flows into several turbines with blades, which pushed by force of water .The turbines turns the shaft which connected to electrical generator and then generates electricity. It is a combined job of turbine and generator, which converts mechanical energy into electric energy. The electrical charge thus is created, collected and then transformers convert this electrical energy into useable electricity. The power lines carry it to all the cities and towns. While transformers in each town convert the power into different kind of electricity for different uses like factories and home.
The energy is virtually free once the dam is built :- The elimination of the cost of fuel is one of the important advantages of hydroelectricity. The price of operating hydroelectricity is immune to increase in the price of fossil fuels such as oil, natural gas or coal. There will be longer economic lives for hydroelectric plants than fuel-fired generation. As there are some plants which are in service and this plants were built in 50 to 100 years ago. As the plants are automated so labor is also getting low.
No waste or pollution created.
Some carbon dioxide is generated during construction of the project; this is a tiny fraction of the operating emissions of equivalent fossil-fuel electricity generation. But otherwise it does not generate any waste products.
It is more reliable than wind, solar or wave power.
Water can be stored in the dam; hence can cope with peaks during demand. Hydro-electric power stations can increase to full power at once, unlike other power stations.
Uninterrupted electricity can be generated.
Reservoirs created by hydroelectric schemes which provide facilities for water sports, and become tourist attractions in themselves.
Multi-use dams placed for irrigation support agriculture with a relatively constant water supply.
Like other energy sources, power generation using water has limitations, including environmental impacts caused by damming rivers and streams, which affects the habitats of the local plant, fish, and animal life.
The dams are very expensive to build.
However, many dams are also used for flood control or irrigation, so building costs can be shared.
Building a large dam can flood a very large area causing problems for animals live there.
Attaining a suitable site can be difficult – the impact on residents and the environment may be unacceptable. Water quality and quantity pressure can be affected, which can have an impact on power plant life.