The use of wind machines can be traced back to as early as 200 B.C. The basic working principle of those wind machines was similar to the wind turbines that are used at present. Wind turbines are rotating machines that convert the kinetic energy in wind to mechanical energy (or potential energy). The machines are referred to as windmills, if the mechanical energy produced is used directly in operating machines, such as pumps. If the energy is converted into electricity, then the machines are called wind generators or aerogenerators.
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Working of Wind Turbines
There are two types of wind turbines, classified based on the axis in which the turbine rotates viz. horizontal-axis wind turbines (HAWT) and vertical-axis wind turbines (VAWT). Among these two, turbines that rotate on horizontal axis are more popularly used than vertical-axis wind turbines. Both the wind turbines work in the same fashion. Let’s take a look at the machinery and working of wind turbines.
When we see a wind turbine, the most significant component is the tower that holds the blades. The efficiency of wind turbines to some extent depends on the height of the tower. In other words, the tower height should be such that the blades can make use of the available wind energy to maximum amount. Following are the machinery of wind turbines:
- Blades or rotor (either two or three)
- Brake (to stop turbine rotation in emergencies)
- Anemometer (for measuring wind speed)
- Controller (regulates the turbine)
- Gear box (to start the machine)
- Generator (for producing electricity)
- High-speed and low-speed shaft (to drive generator)
- Nacelle (houses the turbine and is placed on top of the tower)
- Pitch (for controlling the direction of blades)
- Tower (houses the rotor)
- Wind direction (upwind turbine)
- Yaw drive (required for upwind turbine and is used to regulate rotor direction)
- Yaw motor (powers the yaw drive)
- Wind vane (to measure wind direction)
The working mechanism of wind turbines is very simple. In a wind turbine, the blades are positioned at 45-degree angle, so as to capture maximum kinetic energy from wind. As the broad surface of the blade faces the wind, it creates a positive pressure on the front when the wind hits the blade. This pressure creates a suction behind the blade, which turns the rotor. When wind accelerates and reaches a certain speed (four meters per second), the blade gradually rotates and produces mechanical energy.
The energy produced is then converted into electricity via the generators and stored in batteries for further use. The amount of energy production depends on the rotational speed of turbine, which in turn is directly proportional to the speed of wind. The turbine speed can even reach to about 250 kilometers per hour. However, at very high speeds, the rotation of the blade is ceased with the help of brakes; otherwise, there are chances that strong winds may rip off the turbine blades.
As we have discussed, wind turbines make use of renewable energy source to produce electricity without the emission of greenhouse gases. One can install smaller wind turbines at home to supply power for air conditioner (AC) or inverter. In recent times, wind turbines are gaining popularity to combat global warming and carbon dioxide production in the atmosphere, yet providing energy to meet our lavish lifestyles.