EnGen Roadshow Demo: Water Turbine

How It Works

[demo]
Source: robotshop.com (available for purchase)

Water flows over turbine blades, which cause a shaft to turn. The shaft turns a generator, which produces electricity. The water flow is often created by gravity which forces water to flow downhill. A difference in elevation of two bodies of water creates a pressure difference which induces a water flow from high to low pressure.

[demo]
Source: USGS Georgia Water Science Center

How It Is Used Today

Full-scale versions of these turbines are used in hydroelectric dams all over the world. The animation shows the operation of a typical dam.

[demo]
Source: USGS Georgia Water Science Center

The pros of hydroelectric dams are that they do not pollute after their construction is over, they provide steady, controllable power, and they have a virtually infinite lifetime. The cons of hydroelectric dams are displacement of people due to upstream flooding as well as environmental issues.

History

The flow of water has been used since ancient times. Before electricity was invented, mechanisms were placed in streams and rivers to transfer the energy of the water flow into mechanical energy. Such mechanisms were used to grind flour, for example. Bernard Forest de Belidor was the inventor of many of these mechanisms.

After the invention of electricity, the first light bulb lit by the flow of water was in England in 1878. The first electricity produced by a dam in the United States occurred in 1881 near Niagara Falls. By 1889 there were 200 hydroelectric power plants in the US. At two different times the United States was home to the world's highest electricity producing dams. The Hoover Dam in Nevada was the largest in 1936, and was eclipsed by the Grand Coulee Dam in Washington state in 1942. It is now currently the world's fifth largest, with the world's largest in China. It is called the Three Gorges Dam and outputs over three times the electricity of the Grand Coulee Dam.

Projects You Can Do At Home

www.energyquest.ca.gov/projects/hydro-power.html
www.sciencebuddies.org/science-fair-projects/project_ideas/Energy_p021.shtml

Additional Information

Wikipedia: en.wikipedia.org/wiki/List_of_largest_hydroelectric_power_stations