A water turbine is a rotary engine that takes energy from moving water.

Water turbines were developed in the nineteenth century and were widely used for industrial power prior to electrical grids. Now they are mostly used for electric power generation. They harness a clean and renewable energy source.

Water turbines are generally considered a clean power producer, as the turbine causes essentially no change to the water. They use a renewable energy source and are designed to operate for decades. They produce significant amounts of the world's electrical supply.

Historically there have also been negative consequences, mostly associated with the dams normally required for power production. Dams alter the natural ecology of rivers, potentially killing fish, stopping migrations, and disrupting peoples' livelihoods. For example, American Indian tribes in the Pacific Northwest had livelihoods built around salmon fishing, but aggressive dam-building destroyed their way of life. Dams also cause less obvious, but potentially serious consequences, including increased evaporation of water (especially in arid regions), build up of silt behind the dam, and changes to water temperature and flow patterns. Some people believe that it is possible to construct hydropower systems that divert fish and other organisms away from turbine intakes without significant damage or loss of power; historical performance of diversion structures has been poor. In the United States, it is now illegal to block the migration of fish so fish ladders must be provided by dam builders. The actual performance of fish ladders is often poor.

For more information see the following links:

• History
• Theory of Operation
• Types of Water Turbines
• Design, Application and Maintenance

Water Turbine Gallery

Kaplan turbine and electrical generator cut-away view.	The runner of the small water turbine
A Francis turbine runner, rated at nearly one million hp (750 MW), being installed at the Grand Coulee Dam	A propeller-type runner rated 28,000 hp (21 MW)
Figure from Pelton's original patent (October 1880)	A Francis turbine at the end of its life showing cavitation pitting, fatigue cracking and a catastrophic failure. Earlier repair jobs that used stainless steel weld rods are visible.

References

1. ^ W. A. Doble, The Tangential Water Wheel, Transactions of the American Institute of Mining Engineers, Vol. XXIX, 1899.
2. ^ W. F. Durrand, The Pelton Water Wheel, Stanford University, Mechanical Engineering, 1939.
3. ^ Cline, Roger:Mechanical Overhaul Procedures for Hydroelectric Units (Facilities Instructions, Standards, and Techniques, Volume 2-7); United States Department of the Interior Bureau of Reclamation, Denver, Colorado, July 1994 (800KB pdf).
4. ^ United States Department of the Interior Bureau of Reclamation; Duncan, William (revised April 1989): Turbine Repair (Facilities Instructions, Standards & Techniques, Volume 2-5) (1.5 MB pdf).

External links

• Introductory turbine math
• European Union publication, Layman's hydropower handbook,12 MB pdf
• "Selecting Hydraulic Reaction Turbines", US Bureau of Reclamation publication, 48 MB pdf
• "Laboratory for hydraulique machines", Lausanne (Switzerland)
• DoradoVista, Small Hydro Power Information