Wind, in fact, is also a form of solar energy because winds develop when the earth’s surface is heated up with the solar radiation. To be more precise, the topography of the earth’s surface that consist of plain land, high hills, water bodies and the oceans receive and absorb the rays of the Sun at different levels as a result of which, the heated air above them behaves differently. This disparity of warm air causes wind to flow, while the gust of air so flowing is described as wind power or wind energy. Wind energy was previously utilized by sailing ships for faster transit through the high seas, pumping water from the wells and for crushing corn, while its contemporary use is directed to power generation through wind turbines.
Simply stating, a wind turbine acts more or less like an electric fan, the only difference being its working principle which is just the opposite of that of the latter. In other words, while the electricity makes the fan to turn its blades, the same is generated when wind turns the turbine’s blades. What really happens is that, when wind energy turns the blades of a wind turbine, it turns a shaft attached to it which in turn, rotates the wheel of a generator, producing electric current.
Present day wind turbines usually fall into two basic types – the horizontal-axis type and the vertical-axis type of which the former type is more in use for generation of electricity. However, it would be easier to understand how wind energy works if we take a look at the working of the turbines and get acquainted with its distinctive parts that are described here. The entire assembly consist of (a) An Anemometer that measures up the wind speed and transmits the same to the controller; (b) a Controller that starts up the turbine at wind speeds ranging from 9 to 18 mph (miles per hour) and shuts it off when it reaches or goes beyond 55 mph as much higher speeds tend to damage the system. Wind turbines are invariably provided with Blades (two or three for each turbine) that ‘lift’ and rotate as the wind blows over them. Most turbines are also provided with Brakes that can be applied mechanically or hydraulically to stop the Rotor (the blades and the hub) in emergencies. The Low-speed shaft in turbine turns the rotor at revolutions varying from 30 to 60 rpm while the High-speed shaft drives the Generator which actually is an off-the-shelf power generator that produces a 60-cycle AC current.
Apart from the components that have been described above, a Wind Turbine also have a few other components that consist of a Gear box which connects the low-speed shaft to the high-speed shaft, thereby increasing its rotational speed to 1000 – 1800 rpm, which is the highest. There is a tendency now towards eliminating this costly component, replacing the system with ‘direct-drive’ generators that can operate at lower rpm.
Also included in the assembly is a Nacelle that sits atop the Tower containing the gear box, controller, both kinds of the shafts, brakes, etc which sometimes is large enough for a helicopter to land on it. Besides, the turbines are also provided with Pitch that can control the blades by changing their slants while in motion. And of course, there is the Tower that is made from tubular steel, reinforced concrete or steel lattice on top of which the whole contraption sits smug.
Although the basic description of how the wind energy works through a wind turbine has been provided here, several variations of this system are being worked out at different parts of the country, some of which can actually produce more electricity at a much lower rotor rpm because of the ingenuity of their design structures. But the fundamentals remain the same. But all said and done, power generation through wind turbines still depends on the whims of nature that can lower the volume of wind all on a sudden or stop it temporarily for some time.