See also:

• Hydroelectricity Generation


• Hydroelectricity Advantages and Disadvantages

Water Power
Hydroelectricity Micro Hydro Wave Power Tidal Power OTEC Deep Lake Cooling Blue Energy

Hydroelectricity is a form of hydropower, and is the most widely used form of renewable energy. It produces no waste, and does not produce carbon dioxide (CO₂) which contributes to greenhouse gases. Hydroelectricity now supplies about 715,000 MWe or 19% of world electricity (16% in 2003), accounting for over 63% of the total electricity from renewables in 2005.^[1]

Although large hydroelectric installations generate most of the world's hydroelectricity, small hydro schemes are particularly popular in China, which has over 50% of world small hydro capacity.^[1] Some jurisdictions do not consider large hydro projects to be a sustainable energy source due to human and environmental impacts, though this judgment depends on the definition of sustainability used.^[2]

Most hydroelectric power comes from the potential energy of dammed water driving a water turbine and generator. In this case the energy extracted from the water depends on the volume and on the difference in height between the source and the water's outflow. This height difference is called the head. The amount of potential energy in water is proportional to the head. To obtain very high head, water for a hydraulic turbine may be run through a large pipe called a penstock.

Countries with the most hydro-electric capacity

The ranking of hydro-electric capacity is either by actual annual energy production or by installed capacity power rating. A hydro-electric plant rarely operates at its full power rating over a full year; the ratio between annual average power and installed capacity rating is the load factor. The installed capacity is the sum of all generator nameplate power ratings. Sources came from BP Annual Report 2006 ^[3] List of the largest hydoelectric power stations

For more information see the following links:

• Hydroelectricity Generation


• Hydroelectricity Advantages and Disadvantages

Hydroelectricity Gallery

Hydraulic turbine and electrical generator.	Hydroelectric dam in cross section
The upper reservoir and dam of the Ffestiniog pumped storage scheme. 360 megawatts of electricity can be generated within 60 seconds of the need arising.	Recreational users must exercise extreme care when near hydroelectric dams, power plant intakes and spillways.[6]
Bonnington hydroelectric power station, River Clyde, Scotland.	The pipes supplying water from the River Clyde to Bonnington hydroelectric power station, Scotland.
The hydroelectric power station of Aswan Dam, Egypt	Hydroelectric Reservoir Vianden, Luxembourg

References

• New Scientist report on greenhouse gas production by hydroelectric dams.
• International Water Power and Dam Construction Venezuela country profile
• International Water Power and Dam Construction Canada country profile
• Tremblay, Varfalvy, Roehm and Garneau. 2005. Greenhouse Gas Emissions - Fluxes and Processes, Springer, 732 p.

External links

• Hydroelectricity at the Open Directory Project
• Mechanicville Hydroelectric Station Tour Video
• National Hydropower Association, USA
• Hydropower Reform Coalition, USA
• Interactive site that demonstrates dams' effects on rivers
• Center of expertise on hydropower impacts on fish and fish habitat, Canada
• Hydro-Québec
• CBC Digital Archives – Hydroelectricity: The Power of Water
• University of Washington Libraries – Seattle Power and Water Supply Collection
• United States Federal Energy Regulatory Commission (FERC)
• European Small Hydropower Association
• Power at Niagara Falls Niagara Falls Public Library (Ont.)
• Milford Hydroelectric Station Restoration Tour Built by Henry Ford in 1939