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Moving air is called wind and it possesses Kinetic energy. In the earlier days, it was utilized by man in winnowing to remove husk from grains, in propelling sail boats in rivers and seas for transport purposes. But nowadays this wind energy is used to produce electricity.
Solar energy is responsible for the blowing of wind. The intensity of sun-rays is stronger near the Equator than at the Polar Regions. Due to unequal heating of the earth's surface, cooler air from the Polar Regions flow towards the equatorial regions to fill the space created by the hot rising air. Air flows from high pressure region to low pressure region. This flow of air from one place to another constitutes wind.
The energy of wind is used for working of flour-mills and water-lifting pumps with an electric generator. Such simple machines which work due to kinetic energy of wind are called wind mills.
The Principle of Windmill
When the blowing wind strikes across the blades of a windmill, it exerts a force on them due to which the blades of the windmill start rotating. This in turn rotates the shaft of the turbine and generates electricity.
Working of the Windmill
Wind turbines are used to produce electricity. The machines that generate electricity are the most conventional type with airfoil propeller employing two to three tapered blades. Electricity can be produced by rotating an armature in between the poles of a strong magnet. The shaft of the armature of a generator is connected to the wind turbine by a connecting rod. When the wind rotates the blades of the wind turbine, the shaft rotates, and this in turn rotates the armature, thereby producing electricity.
The wind speed should be higher than 15 km/h to maintain the required speed of the turbine.
One advantage of wind energy is that it is available everywhere and in plenty. We will never run out of wind power. It does not create any kind of pollution; like smoke and harmful gases or harmful radiations.
Even though wind energy is available in plenty, wind is not available at all times. It is unpredictable and not dependable. Hence to produce maximum amount of energy from wind, wind energy maps are prepared, which give us an idea of the average wind speed throughout the year at different places. The maps give annual average, average for January (a typical low wind month) and an average for July (a typical windy month). The maps also provide information about energy available in one square meter of a wind stream at about 10 m high above the ground level.
For large scale production, a 'wind farm' with a hundred or more wind turbines is needed. The turbines must be sited in windy areas which are often the most attractive parts of the landscape.
The energy output of each windmill in a farm is coupled together to get electricity on a commercial scale.
The wind power potential of our country is estimated to be about 45,000 MW. At present we are able to generate 380 MW of electricity from the largest wind energy farm established near Kanyakumari in Tamil Nadu. India ranks fifth in harnessing wind energy for the production of electricity.
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