Hydro power

Energy in water (in the form of motive energy or temperature differences) can be harnessed and used. Since water is about 800 times denser than air, even a slow flowing stream of water, or moderate sea swell, can yield considerable amounts of energy.

There are many forms of water energy:

  • Hydroelectric energy is a term usually reserved for large-scale hydroelectric dams.

  • Wave power
    uses the energy in waves. The waves will usually make large pontoons go up and down in the water, leaving an area with reduced wave height in the "shadow". Wave power has now reached commercialization.
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  • Tidal power captures energy from the tides in a vertical direction. Tides come in, raise water levels in a basin, and tides roll out. Around low tide, the water in the basin is discharged through a turbine.
  • ·          
  • Tidal stream power captures energy from the flow of tides, usually using underwater plant resembling a small wind turbine. Tidal stream power demonstration projects exist, and the first commercial prototype will be installed in Strangford Lough.

  • Ocean thermal energy conversion
    (OTEC) uses the temperature difference between the warmer surface of the ocean and the colder lower recesses. OTEC has not been field-tested on a large scale.

The major advantage of hydroelectric systems is the elimination of the cost of fuel. Other advantages include longer life than fuel-fired generation, low operating costs, and the provision of facilities for water sports.





Best and Biggest



Portugal now has the world's first commercial wave farm, the Aguçadora Wave Park, established in 2006.


Since 1967, the La Rance tidal power plant, near Mont Saint Michel, generated annually 600 million kWh using its 24 turbines of 10 MW.



South Korea plans to build world’s largest tidal power plant – 254 MW. Investment will be made by the Korean government.



The largest hydroelectric power plant is located on the “Three gorges” dam situated in the middle course of Yangzi river in China. The construction of “Three gorges” hydroelectric power plant started in 1993, and costs approximately 26.36 billion USD. Dam’s length is 2309 m and the height – 185. After setting into operation of the full capacity it is expected to produce 84.7 billion KWh of electric power per year. Construction will be finished this year.


The Itaipú hydroelectric power plant is the largest development of its kind in operation in the world. Built from 1975 to 1991, in a joint development on the Paraná River, Itaipú represents the efforts and accomplishments of two neighboring countries, Brazil and Paraguay. The power plant's 20 generating units add up to a total production capacity of 14,000 MW (megawatts).

With its generating capacity of 864 MW, hydroelectric pumping power plant “Chaira” is the largest hydroelectric pumping power plant in Bulgaria and South East Europe.