Wind power converts the kinetic energy in wind to generate electricity or mechanical power. This is done by using a large wind turbine usually consisting of propellers; the turbine can be connected to a generator to generate electricity, or the wind used as mechanical power to perform tasks such as pumping water or grinding grain. As the wind passes the turbines it moves the blades, which spins the shaft. There are currently two different kinds of wind turbines in use, the Horizontal Axis Wind Turbines (HAWT) or the Vertical Axis Wind Turbines (VAWT). HAWT are the most common wind turbines, displaying the propeller or ‘fan-style’ blades, and VAWT are usually in an ‘egg-beater’ style.
Converting Wind to Mechanical Energy
Wind is converted by the blades of wind turbines. The blades of the wind turbines are designed in two different ways, the drag type and lift type.
• Drag type: this blade design uses the force of the wind to push the blades around. These blades have a higher torque than lift designs but with a slower rotating speed. The drag type blades were the first designs used to harness wind energy for activities such as grinding and sawing. As the rotating speed of the blades are much slower than lift type this design is usually never used for generating large scale energy.
• Lift type: most modern HAWT use this design. Both sides of the blade has air blown across it resulting in the air taking longer to travel across the edges. In this way lower air pressure is created on the leading edge of the blade, and higher air pressure created on the tail edge. Because of this pressure difference the blade is pushed and pulled around, creating a higher rotational speed that is needed for generating electricity.
Creating Electricity from Wind
To create electricity from wind the shaft of the turbine must be connected to a generator. The generator uses the turning motion of the shaft to rotate a rotor which has oppositely charge magnets and is surrounded by copper wire loops. Electromagnetic induction is created by the rotor spinning around the inside of the core, generating electricity.
Distribution of Electricity
The electricity generated by harnessing the wind’s mechanical energy must go through a transformer in order increase its voltage and make it successfully transfer across long distances. Power stations and fuse boxes receive the current and then transform it to a lower voltage that can be safely used by business and homes.