Wind energy is harnessed through the use of wind turbines which are normally mounted on towers. Horizontal axis wind turbines and vertical axis wind turbines are the two types of wind turbines that are normally used. The wind towers are usually erected twenty meters high or more above the ground for maximum harnessing of wind energy since there are stronger winds at these heights. Wind turbines are therefore used to convert the wind power into wind energy and eventually to electricity. A wind turbine is composed of three propellers mounted on a shaft to form rotor and the rotation of the rotor applies the principles of Bernoulli Effect. When wind blows over the propeller blades, a region of low pressure is formed on the bottom of each blade. The low pressure region formed at the downwind side of the blade causes the blade to move towards it and subsequently causing the rotor to turn. Consequently the side of the propeller blade that is on the frontward side experiences a much lesser force. This unequal pressure in the propeller blades causes the rotor to spin and eventually turning the generator for electricity generation (Fitzgerald & Voege, 2010).
Conversion of Wind into Electricity
The spinning of the tower produces kinetic energy which is converted to electricity via the generators. The kinetic energy from the rotor is converted to electricity by use of magnets situated in the generators. Inside the generators, the magnets move over a stator, this consists of numerous coils of wire and hence producing alternating current (AC) electricity. The alternating current (AC) electricity is then converted to direct current (DC) electricity which can eventually be used to store the electrical energy in batteries or in the grid interactive inverter for power supply in the main grid. For maximum electricity through this system, it is advisable that the wind turbines to be situated in places where there are no interferences and ideally they should be situated at the country, farm lands or at the coast where there are minimal interference to the wind speed. The amount of wind that is harnessed and converted to electricity depends on the size of the turbine and the speed of the winds (Dodge, 2006).