Energy Generation and Storage Using Water  Printable view

Electricity generation using water

Have you seen photos of the Niagara Falls in southeastern Ontario, Canada? They are perhaps the most spectacular water falls in the world. If you visit Niagara Falls you will see water rushing over the cliff edge with a thunderous roar. A great amount of energy is released as the water falls. Do you know where this energy comes from?

Fig. 1   A spectacular view of the Niagara Falls (Photo credit: Parsons, David and NREL/DOE)   Fig. 2   As water falls, it gains kinetic energy.

To explain where the energy of the falling water comes from, let's recall the principle of conservation of energy. The principle states that energy can neither be created nor destroyed, but can only be converted from one form to another. Water at the top of a very high waterfall possesses gravitational potential energy. As the water falls, this energy is converted into kinetic energy, resulting in a flow at a high velocity.

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As the falling water collides with the bulk of the water at the bottom of the waterfall, water splashes randomly and chaotically in all directions. Part of the kinetic energy gained by the falling water is now converted into the kinetic energy of random motion. As a result, the internal energy of the water increases, and the water temperature rises at the bottom of the falls. It is said that in the 19th century, the famous scientist James Joule first attempted to measure the temperature change of water at a waterfall. His contribution towards the discovery of conservation of energy resulted in the unit of energy joule being named after him.

Fig. 3   Hydroelectricity is an important renewable energy source.

Is it possible to capture part of the kinetic energy generated by falling water and convert it to a useful form, instead of letting it all dissipate? This is exactly what a hydroelectric power station does. Hydroelectricity is the generation of electricity using the kinetic energy of water. In the case of a waterfall, gravitational potential energy of water first changes into the kinetic energy of water. This kinetic energy is partially converted into electrical energy by a generator.

In Canada, water from Niagara Falls was first diverted for hydroelectricity in 1893. In 1921, the Sir Adam Beck Generating Station No.1 began diverting water from the falls into tunnels to produce electricity. It was once the largest hydroelectric power station in the world.