From ArticleWorld

Hydroelectricity refers to the power which is derived from the energy which is possessed by water bodies. In most cases, hydropower is derived from the potential energy which is present in water stored in large reservoirs. Waterpower exists as a natural resource, and hence is considered to be a form of renewable source of energy.


Forms of hydroelectricity

Most hydroelectric power comes from dams, which are built on the courses of major rivers. Expensive construction may be required to make available storage lakes, bypass canals and turbine-generator sets. Water collected in the reservoir is sent through specially built pipes called penstocks to drive turbine-generator sets at high speeds and as a result generate electricity. Water that is sent out is released from the so-called tailrace. The higher the dam, greater is the capacity.

Thus, power generated depends upon the ‘potential head’ offered by the dam.

  • Pumped-storage plants are sometimes used during peak load demands; these can be used to store water during off-peak conditions.
  • Run-of-the-river plants are also used at times, as in the Niagara Falls in the United States. They utilise the steady flow of water.
  • Less commonly, hydropower can be obtained from sources such as ocean tidal power. These effectively make use of the alternately rising and falling tides of oceans in order to run turbines.

Hydroelectricity around the world

Hydroelectricity supplies over 20% of the world’s electricity needs. Countries like Norway, Iceland, Canada and Austria produce well over 70% of their electricity supplies through hydroelectricity. Hydro capacity is normally used during peak-load demands since it can be easily stored during low-load periods. This is because water sources may not be very common. There are several examples of hydroelectricity being used for private purposes. This is possible when water is available abundantly. Hydroelectric capacities of around 1KW to 1MW are common in several Chinese districts.

Development of hydroelectricity

Waterwheels were common right from the time of the ancient Greeks and through the middle ages. Waterwheels were developed for textile mills, leather factories and paper mills during the early stages of the development of America. It was in the last century that water power began to be harnessed extensively for electricity generation purposes. Developing nations too have seen great strides.

Advantages and disadvantages of hydroelectricity

The main advantage of hydroelectricity is that no fossil fuel is required. Hence it is independent of the sky-rocketing prices of fuel.

Maintenance and running costs are very low as compared to other forms of generation. There is no question of air pollution. Dams can be used for flood control, irrigation, and for tourists’ recreation.

Some of the main disadvantages of this form of power are that the initial investment is very high, the aquatic life may be disrupted and that greenhouse gases can be produced due to vegetation decaying in newly-flooded areas.