What Is a Water Turbine?

Large water turbines provide electrical energy.

A turbine is a wheel with blades that can be turned by moving sources such as air, steam or water. The water turbine works by using a water source to produce electrical power. Depending on the size of the water turbine, the water source can be a river, stream, lake or pond. Waterwheels were used in ancient times. However, to produce more efficient energy, turbines were developed in the late 1700s.

Function

Water turbines are used to generate electricity and provide about 20 percent of the world's electrical power. Canada, with its many rivers and streams, uses water turbines to generate 70 percent of its electricity. The United States only gets 6.6 percent of its electrical power from water turbines.

Features

A water turbine is a simple power-generating system made up of several parts. These parts are the powerhouse, which protects the water turbine from the elements, the intake shaft, the runner, the generator and generator shaft, an exit valve and a water nozzle, which is found only on impulse turbines.

Impulse Turbine

The impulse turbine belongs to one of two categories generally used to classify water turbines. The impulse turbine has a runner that operates on air, and is turned by one or more multiple jets of water which comes in contact with the blade. This type of turbine also has a water nozzle that converts pressurized low-velocity water into a high-speed jet.

Reaction Turbine

The other category of water turbine is the reaction turbine. This type does not need a water nozzle because it is immersed in water. The reaction turbine is enclosed in a pressure casing and has angled runner blades. The angled blades are designed to allow pressure differences across them to create lift forces. The lift forces are what causes the runner blades to rotate.

Types

There are many different types of water turbines designed for different energy needs. These water turbines include the Turgo, Pelton, Francis, Propeller and Cross-flow, which is also known as the Michael Banki turbine. The type of water turbine depends on the amount of water pressure available. Choices will also depend on whether water jets are appropriate, in which case it would require an impulse turbine. If the turbine is to be suspended in water, the choice would be a reaction turbine.

Considerations

Water turbines provide a source of hydroelectricity that is considered renewable energy. It does not generate pollution or hydrocarbons. Additionally, it can provide decades of pollution-free energy. However, it can disrupt fish migration when used in rivers, and if water reservoirs are man-made, they can displace wildlife.

References

• Water Energy: Water Turbines
• Water Energy: Large Hydroelectric Systems
• Stockdale Mill: What Is a Turbine?