How Does a Hydroelectric Dam Work

How Does a Hydroelectric Dam Work

The power of falling water is unlocked by a hydroelectric dam in the form of electricity. In this article, we will look at how hydroelectric dams work, and what are their advantages and disadvantages.

Hydroelectric power produced by hydroelectric dams accounts for 20% of the world’s total production of electrical energy. Although human beings have been using the power of water for around 2000 years now, the idea of generating electricity from it only started in the mid-20th century.

Working of a Hydroelectric Dam

A hydroelectric dam converts potential energy (and/or kinetic energy) to electrical energy by means of a turbine and alternator.

A typical hydroelectric dam has the following main parts:

•Water reservoir: A large quantity of water is stored in a reservoir (or dam). The height or depth of the stored water determines how much electricity can be generated. As the depth increases, the generation of electricity also increases.

•Gate: A control gate is used for releasing/blocking water from the dam. Depending upon the electricity requirements, the gate is opened.

•Penstock: The released water from the dam reaches the turbine blade through the penstock. The proper slope and diameter of the penstock is important for the efficiency of the dam.

•Turbine: The turbine consists of a number of large fan blades and a spindle. The spindle rotates when water strikes the blades. Thus the power of flowing water is converted to the rotational power of the spindle.

•Alternator: The spindle of the turbine is connected to the alternator, where rotational power of the spindle is converted into electrical power. The produced electricity is then distributed to the grid.

•River: The outflow of water from the turbine is released to a river.

Advantages of Hydroelectric Dams

•Cheap electricity: The operating cost of a hydroelectric dam is very minimal as there is no costly fossil fuel required. Moreover, life of a hydroelectric dam is much more than that of a thermal power plant.

•Less green house gas: A hydroelectric power plant produces lesser amounts of green house gases as compared to a thermal power plant.

•Tourism value: The dam of a hydroelectric power plant can be used as a tourist spot.

Disadvantages of Hydroelectric Dams

•Effect on eco-systems: Construction of a dam affects the eco-system (especially water eco-system) of the surroundings. Some species of fishes cannot increase their population because of dams.

•Relocation: For constructing a dam, relocation of the human and animal population of that area is required.•Green house gas emission: The blocked water in the dam causes generation of green house gas.


Construction of a hydroelectric dam requires design feasibility study of the dam with the considerations of advantages and disadvantages of hydroelectric dam. A hydroelectric dam works on the principle of law of conservation of energy. It converts hydraulic energy to electrical energy.

Iran Engineering Reference Encyclopedia

How Does a Hydroelectric Dam Work

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تاریخ: یکشنبه 2012/07/22
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