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Back Mechanical Mechanical Engineering Dictionary Hydraulics Hydro Electric Power Plant - Main Parts, Advantages & Disadvantages of Hydro Electricity

Hydro Electric Power Plant - Main Parts, Advantages & Disadvantages of Hydro Electricity


Hydroelectricity is the term referring to electricity generated by hydro power;

the production of electrical power through the use of the gravitational force of falling or flowing water.

It is the most widely used form of renewable energy. Once a hydroelectric complex is constructed, the project produces no direct waste.

Main parts of hydro electric power plant

  1. Water reservoir
  2. Dam
  3. Head works
  4. Water ways
  5. Power house and tail race

Advantages and disadvantages of hydroelectricity:


The major advantage of hydroelectricity is elimination of the cost of fuel. The cost of operating a hydroelectric plant is nearly immune to increases in the cost of fossil fuels such as oil, natural gas or coal, and no imports are needed.

CO2 Emissions:

Since hydroelectric dams do not burn fossil fuels, they do not directly produce carbon dioxide. While some carbon dioxide is produced during manufacture and construction of the project, this is a tiny fraction of the operating emissions of equivalent fossil-fuel electricity generation

Other uses of the Reservoir:

Reservoirs created by hydroelectric schemes often provide facilities for water sports, and become tourist attractions themselves. In some countries, aquaculture in reservoirs is common. Multi-use dams installed for irrigation support agriculture with a relatively constant water supply. Large hydro dams can control floods, which would otherwise affect people living downstream of the project.


Large reservoirs required for the operation of hydroelectric power stations result in submersion of extensive areas upstream of the dams, destroying biologically rich and productive lowland and reverie valley forests, marshland and grasslands. The loss of land is often exacerbated by the fact that reservoirs cause habitat fragmentation of surrounding areas.

Generation of hydroelectric power changes the downstream river environment. Water exiting a turbine usually contains very little suspended sediment, which can lead to scouring of river beds and loss of riverbanks. Since turbine gates are often opened intermittently, rapid or even daily fluctuations in river flow are observed


When water flows it has the ability to transport particles heavier than itself downstream. This has a negative effect on dams and subsequently their power stations, particularly those on rivers or within catchments areas with high salutation. Salutation can fill a reservoir and reduce its capacity to control floods along with causing additional horizontal pressure on the upstream portion of the dam

Flow shortage:

Changes in the amount of river flow will correlate with the amount of energy produced by a dam. Lower River flows because of drought, climate change or upstream dams and diversions will reduce the amount of live storage in a reservoir therefore reducing the amount of water that can be used for hydroelectricity. The result of diminished river flow can be power shortages in areas that depend heavily on hydroelectric power.

Calculating the amount of available power

A simple formula for approximating electric power production at a hydroelectric plant is: P = ρhrgk, where

  • P is Power in watts,
  • ρ is the density of water (~1000 kg/m3),
  • h is height in meters,
  • r is flow rate in cubic meters per second,
  • g is acceleration due to gravity of 9.8 m/s2,
  • K is a coefficient of efficiency ranging from 0 to 1. Efficiency is often higher (that is, closer to 1) with larger and more modern turbines.

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