Wind Turbines: Turning Wind to Power
For us to know about how wind turbines generate electricity, let us first answer a very important question.
Wind turbines: These are devices that convert winds kinetic energy into mechanical energy.
In this article, the word “wind turbine” refers specifically to a wind generator. Wind turbines have a variety of shapes and sizes, but they are all composed of the same 3 basic parts. There three basic parts are the:
a) Rotor Blades: These are the “wind catchers” of a wind turbine. They are long projections that have aerodynamic designs. When wind passes, it forces these rotor blades to turn.
b) Shaft: This is a rod that connects the rotor blades to the generator. Its main purpose is to transfer the rotational mechanical energy of the rotor blades to the generator.
c) Generator: Finally, this device is designed to convert mechanical energy into electrical energy. It uses the principle of electromagnetic induction.
Now that we know its basic parts, let us understand how wind turbines generate electricity. The processes involved include the following:
A) Capturing Wind Energy
Wind energy is captured using the wind turbine rotor blades. When wind passes through the blades, two aerodynamic forces are at work. These two forces cause the rotor blades to turn, depending on how much force the wind exerts on them. The process converts the wind’s kinetic energy to mechanical energy (turning of rotor blades). After this, it is time to convert the mechanical energy into electricity.
B) Converting to Electricity
The turning of the rotor blades would simultaneously cause the shaft to turn, which is connected to a generator. When the rotor blades turn, the shaft also turns. This makes the generator produce electricity. In this process, the rotational mechanical energy of the shaft is converted to electricity by the generator.
C) Other Processes Involved
1) Increasing RPM (Revolution per Minute)
You might notice that large wind turbines turn slowly. On average, their rotor blades rotate at a speed of 20 rpm (rotations per minute). 20 rpm is too slow to power up a generator. Large wind turbines use a gearbox to increase the rpm from 20 rpm to as much as 2000 rpm.
2) Yaw Adjustment (For HAWTs only)
HAWTs (horizontal-axis wind turbines) should be directed the same direction as the wind to maximize the energy collected. Wind direction is not constant, so modern HAWTs use a yaw-adjustment system to position the rotor blades in the correct direction. The system usually consists of a sensor to monitor wind direction and a motor to adjust turbine direction.
3) Braking Mechanism
Finally, there are places where wind speeds can reach extremely high levels. Over-speeding of the rotor blades can cause malfunctions on the wind turbine system. This is why a braking mechanism should exist to limit the maximum speed of the rotor blades.
Let us be thankful to technology because modern wind turbines now have a host of other features that help in solving problems such the scarcity of alternative energy for our limited energy resources like coal, petroleum oil and some natural gases, and also the worsening effects of global warming.