Hydropower refers to the harnishing of falling or moving water to direct energy into something that can be used for a useful purpose. Hydropower has a long history and takes several main forms.

Historic Types of Hydro Power

Before the discovery of electricity hydro power was used in irrigation, to power saw mills, grain mills, textile mills and other types of machinery. Many mills used a waterwheel placed under a small set of falls. The water would turn the waterwheel which through gears and pullys would turn the machinery inside.

Water was also used in various cultures to operate pumps that moved water into irrigation channels.

Rushing water, either naturally occuring or man-made via dams, has long been used in mining to accomplish work like moving ore.

Conventional Generation of Hydroelectric Power

During the 20th Century many countries moved toward generating electricity with hydro power. There are various methods that have been employed but the largest scale method is to build a large dam to control and channel water in a river. The water is than released over or through the dam through large turbines that spin to generate electricity. For example, British Columbia (BC Hydro) and Quebec (Quebec Hydro) developed substantial Hydro electric generating capacity through the mid part of the 20th century and the sold this electricity to the US to meet American demand. China continues to expand its hydro electric capacity with huge dams under construction. Here is a list of conventional hydro electric dams.

A variation on the traditional hydro electric dam is the pumped storage dam and generating station. Electricity on the grid can not be easily stored, but the demand for electricity varies throughout the day and by season.When demand for power is lower,a pumped storage facility will use some of the power it generates to pump water into a storage reservar. When demand increases the power station will draw on this stored water to generate additional power for the grid, These facilities serve an important function in delivering power on demand to he grid.

A run of the river hydro electric project uses kenetic energy present in streams and rivers to generate electricity. These projects are smaller scale because no dam is required. While they are less disruptive to the landscape than constructed dams, run of the rivedr projects do not really have the ability to add and delete power from the grid on demand except by shutting off the generators or turning them on. This is because they do not store water for peak demand.

Less common are tide powered generating stations that utilize the very predictable movements of the tide to power turbines.

Emerging Types of Hydro Power

Research continues on systems that can capture the energy in ocean waves.

Micro and Pino Hydro Electric projects are being used to power single indistries or small communities that are too far from the grid to serve cost effectively.

Hydropower is Clean Energy

Because the water is only used for generating the energy, and not destroyed hydro power is considered one of the cleanist and most efficent ways of generating electricity in the world.

Some fossel fuels are used to build hydro power plants and dams, but this is only a tiny fraction of the fossel fuels that would be required to generate the power that the hydro facility can generate over its life.

Hydro electric dams and facilities are generally long lasting because they have a low maintenance simple design. Some hydro electric plants are still in use over 100 years after construction. They also are highly automated, requiring only a small staff to supervises.

Hydro Power Negitives

Hydro power is also seen as a negitive in some areas. Compaints against hydro projects include:

  • Possibility of Dam Failure and resulting loss of life and property. This risk is far less in the run of the river projects which do not have dams.
  • Displacement of people and towns to reserviors. A February 2008 study by the World Bank sponsored World Commission on Dams estimated that 40-80 million people worldwide have been physically displaced as a direct result of hydro electric dam construction
  • Loss of land and ecosystem to flooding caused by dams.
  • Flow shortage on the rivers downstream of the dam that can hurt crops, water rights and more.

World Hydro Power Capacity

China, Canada, Brazil, the USA and Russia lead the world in hydro power production. Brazil, Canada, Norway, Paraguay, Switzerland, and Venezuela are the only countries that derive most of thier power from hydro electric sources. Paraguay actually generates 100% of its internal power needs from hydro sources plus exports 90% of its production to Brazil and Argentina.

Ten of the largest hydroelectric producers as at 2009
Country↓ Annual hydroelectric
production (TWh)↓
capacity (GW)↓
% of total
China 652.05 196.79 0.37 22.25
Canada 369.5 88.974 0.59 61.12
Brazil 363.8 69.080 0.56 85.56
United States 250.6 79.511 0.42 5.74
Russia 167.0 45.000 0.42 17.64
Norway 140.5 27.528 0.49 98.25
India 115.6 33.600 0.43 15.80
Venezuela 85.96 14.622 0.67 69.20
Japan 69.2 27.229 0.37 7.21
Sweden 65.5 16.209 0.46 44.34