Water power

Water power, energy obtained from flowing or falling water used to run machinery or create electrical power. Water has been used to drive devices since ancient times, beginning with the invention of the water wheel. Streaming water flowing over the blades of a wheel caused the wheel to rotate, setting in motion other mechanisms—thus creating the energy that drove the mechanisms. Water was first used to power grinding stones that ground grains. Water power was very important during the Industrial Revolution, when it was used to operate factory machines. The most important modern use of water power is the generating of electricity. Hydroelectric power plants producing electrical energy have been built on rivers in many parts of the world. The largest U.S. power plant is the Grand Coulee on the Columbia River in Washington.

See also: Turbine.