Hydroelectric Energy Facts

Located on the Paraná River on the border of Brazil and Paraguay, the Itaipu Dam is the world's largest hydroelectric power facility.
© Michel GUNTHER / WWF
Hydroelectric power is one of the most widely used and cheapest ways to generate electricity today. Although there are a number of environmental issues associated with this form of renewable energy, there are ways to reduce the impacts.

Pollution-free, but with a cost

Hydroelectric power for the most part is pollution-free, but there are environmental and social impacts involved.
The operation of hydropower stations, which includes the construction of dams, can represent a significant disturbance to the natural environment and local communities.

In developing countries, local populations tend to benefit less from hydropower as the generated electricity is often exported to urban regions or outside the country.

Reducing environmental impacts

One low-impact option is to improve existing hydropower stations and make them more efficient.

The process of retrofitting old stations with modern equipment helps ageing dams produce more electricity. Typical investments include:

  • replacing turbines and generators
  • adding machines to facilitate periods of high demand
  • increasing storage capacity by raising the height of the dam
Such modifications can be done relatively quickly, and provide an opportunity to reverse existing environmental damage, such as providing fish passage facilities.

WWF estimates that it may be possible to develop 30% of the economically feasible small-scale hydropower capacity in most river basins or nations without unacceptable impacts.

Additionally, 250GW of large-scale and 20GW of medium-scale hydropower potential could be developed with acceptable impacts, particularly in the least developed parts of the world, such as in Africa.

When constructing new hydropower projects, WWF advocates social and environmental safeguards, which are based on the guidelines of the World Commission on Dams. This includes comprehensive planning to determine energy needs and a thorough options assessment, which evaluates all alternatives.
	© EcoFys
'By 2050, we save nearly €4 trillion per year through energy efficiency and reduced fuel costs'
© EcoFys

Hydroelectric power plants generate about 16% of the world's electricity.

	© WWF Nepal/ Ugan MANANDHAR
The 70kW Ghatte micro-hydro project, supported by WWF-Nepal, is benefitting 108 households from 6 villages in the Everest region.
Hydropower goes back as far as 100 B.C. when the Greeks and Romans used a vertical waterwheel for grinding cereals. In 1882, the world’s first hydroelectric power plant began operating in the United States in Appleton, Wisconsin.

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