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How Hydroelectric Power Works

Omkar Phatak
Of the many ways in which electricity can be generated cleanly, without polluting the environment, the one that harnesses the force of gravity is hydroelectric power. Here we provide you with an explanation of how hydroelectric power works in a nutshell.
About 20% of the world's electrical energy requirement is fulfilled by hydroelectric power. It is the most widely implemented renewable energy generation technology, with the highest market share in the world.

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Every conventional energy resource, including crude oil and coal based fuels utilize the power locked in chemical bonds, that is tapped through oxidation of these fuels, to generate energy. However, they also generate many polluting, green house gases like carbon dioxide in the process, which are byproducts of combustion.
On the other hand, hydroelectric power merely utilizes the motive force provided by water falling under the influence of gravity, to generate electricity, generating no pollutants in the process, while producing substantial power.

About Electric Power Generators

It's essential that you have a bit of a background on how electrical generators work, to fully comprehend how hydroelectric power plants built on rivers and high altitude water sources work.
All electrical generators or dynamos work on the basis of Faraday's law, who is also the inventor of the device. The law states that a changing magnetic field induces an electric current in a conductor. In a dynamo or electric generator, this principle is harnessed to generate power, by rotating a metal rotor through a magnetic field to generate electricity.
As the rotor cuts through the flux of the magnetic field, an electric current is generated in the rotor which can be transferred and stored away to power electric devices. Alternatively a magnet can be rotated around an electrical conductor to generate AC (alternating current) in it.
All electric power plants generate electricity using huge dynamos with giant magnets installed inside and rotors are driven by various methods. In case of a hydroelectric power plant, the rotors are driven by connected turbines, which in turn, are driven by water falling from high altitudes. Let's see hydroelectric power generation in more detail.

How Hydroelectric Power Works?

The first hydroelectric power plant was built by William Armstrong at Cragside, in Northumberland, England, in 1881. Interestingly, this first plant could produce only enough to power a single bulb! Today's hydroelectric power plants generate enough electrical energy to power entire cities.
All hydroelectric plants are necessarily built around water sources like rivers, waterfalls and dams. Here is a phase wise breakdown of how hydroelectric power plants work, by converting mechanical energy of falling water into electricity.

Phase 1: Falling Water From High Altitudes Drives Turbines

Every plant has a water source which can deliver large volumes of water from high altitudes.
A turbine, which is a large wheel with attached blades is placed in the path of falling water, such that its impact makes it rotate. As the gushing water falls down on the turbines, a torque is induced in the turbine, making it rotate. Large hydroelectric plants have a series of such turbines placed at various altitudes in the path of flowing water.

Phase 2: Turbines Rotate Generator Magnets to Produce Electricity
Turbines are connected with electric generators. As the turbine starts rotating, the shaft connected with the generator, makes giant magnets installed inside to rotate around a centrally placed conductor, generating AC in it. This current is supplied to a transformer, which converts the input voltage to provide higher output voltage.

Phase 3: Power Lines Carry Away Generated Power

This power is then supplied to power lines, which supply the generated electrical output away to power stations, for further distribution in homes and industries.
Thus, the mechanical force of falling water is converted into electrical power through the ingenious use of turbine and generator mechanism.
Utilizing all pervading gravity as the driving force, hydroelectric power is the cleanest and most cost-effective electric power generation technology ever developed. All other power generation technologies like nuclear power and coal power based plants pollute the environment, besides requiring costly and fast depleting fuels.
The biggest hydroelectric project in the world currently is the one built on 'Three Gorges Dam', along the Yangtze river in Hubei province of China, which generates a phenomenal 18,200 MW of electric power!
As the impact of pollution on our environment rises, it's increasingly important that we tap such renewable sources of energy.