2016 Feb

Wind Energy: Workings of a Turbine

February 20, 2016

Physics of Wind Turbine

Conventional fossil fuels are sources of energy for hundreds of years. The usage of these fuels is not only environmentally destructive but also unreliable due to the limited nature of these resources. Nuclear energy is an alternative but comes at the cost of higher risk; Fukushima and Chernobyl incidents are the terrifying examples of the huge risk involved with tapping nuclear energy. Solar and Wind energies are relatively safer alternatives and are also sustainable for the sun and wind always readily available. Let’s talk about the workings of a wind turbine.

A wind turbine consists of a long shaft or stand that elevates the turbine on which the head with turbine blades is attached. Before getting into the details of its working, let’s discuss how electricity is generated from magnetic field. A simple experiment that explains it is dropping a magnet through a ring of conducting wire. If you make a ring of conducting wire and attach an ammeter that detects minute currents, and drop a strong magnet through the ring, you can notice that the ammeter deflects, inferring the passage of current. This tells us that a time varying magnetic field creates current in a ring formed from a conducting wire.

The construct of a turbine is similar to that of a motor which we have learnt during our Physics tuition classes on Electromagnetism. A coil is surrounded by North Pole and a South pole of magnets. The coil rotates between these magnets. The coil is attached to the blades of the turbine such that when the blades rotate it is associated with the rotation of the coil. When the coil placed between the magnets rotates, it can be compared with that of a magnet falling through the coil. We know that a magnet falling through a coil creates a magnetic field that varies with time at a given point on the coil.

Now when a coil placed between two magnets moves, the magnetic field at a given point on the coil varies with time. Just like the time varying magnetic field produced current in the case of a magnet falling through ring, current is generated in the coil whenever it moves. This coil is attached to the turbine blades. We know wind rotates these turbine blades that in turn rotate the coil. The rotating coil generates current in it. Thus electricity can be produced from wind energy. Simple it is, isn’t it?

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