Water as Energy

Hydroelectric plants are the largest users of water. 



Gariep Hydroelectric power station


Gariep Hydroelectric Dam  (Photo courtesy of ESKOM)

Hydroelectric plants capture the kinetic energy of falling water to make electricity. They do this with a dam. The dam forces the water level to go up so that the water will have more power when falling. The force of the falling water pressing against the turbine blades cause them to spin.

The spinning turbines transmit the kinetic energy of the falling water to generators. The generators spin when the turbines spin generating electricity that will be transmitted on the power lines to homes and businesses.

Of all the electricity in the world, about 20% is generated by hydropower.  About 10% of all the electricity in the United States is provided by hydropower.

Hydropower generating prevents a lot of pollution.  It is clean and does not leave any waste. Because of the electricity generated by hydropower, the amount of oil and coal needed to produce enough electricity is reduced.

The amount of electricity that a hydroelectric plant produces depends on two things: how far the water falls and the quantity of water falling.


The higher the dam, the further the water falls and the more electric power produced. If the water falls twice as far twice the amount of electricity will be generated. The quantity of water that falls also affects the amount of power produced. The more water that flows through the turbines, making them spin, the more electric power is produced.