The wind turbines can be divided into tow major categories which are horizontal axis and vertical axis wind turbines. However the vertical axis wind turbine can be categorized
into Darrieus turbine and Savonius turbine. The most common type of wind turbines used today is the horizontal axis turbines. These turbines have blades that are similar to the propeller of an airplane.
These turbines are mounted on a tall tower which is about 1200 feet in length. There is a fan like rotor that faces away or into the wind. The tower is tall so that maximum advantage can be taken of the blowing winds. Each blade begins to rotate like the wing of an airplane.
When the wind begins to blow it creates a pocket of low pressure air and this air then pulls the blade towards it. The process of the blade turning is called the lift. The lift force is relatively stronger than the wind force blowing in front of the blades. The force that is created on the front side of the blade is called the drag. This combination of drag and lift rotates the blades of the horizontal wind turbine.
The rotating blades begin to turn the shaft which turns the generator to make electricity. The generated electricity is then transferred to a converter box which can then be used to run the electrical appliances.
In case of vertical axis turbines there are two types. The Darrieus turbine was invented in France by engineer Georges Jean Marie. It has a design similar to an egg beater with vertical blades that rotate according to the wind movement. The turbine works on the principle of aerodynamic lift. This design can produce more energy than the drag design.
The Savonius wind turbine is S shaped. This design was invented by an engineer from Finland called Sigurd Savonius. This design is able to produce lesser power however it is good for smaller tasks such as pumping water and grinding grain. It is very easy to build this design. The most commonly used design is to use a 55 gallon drum and then cutting the drum into two equal parts in the shape of the letter S. You can even scale the design to smaller drums. You can then fit this design into a small transmission so that the rotation speed increases. You can adjust the transmission according to the amount of torque present.