The first wind devices were used in Persia as far back as 230 B.C. for the purposes of grinding grain. By 220 A.D. the Greeks began to use the same process for the same purpose. The Germans started using windmills to drain water from the areas lying in the Local River delta.

Wind Power Generators began to be used for the production of electrical power in the year 1886, and the first such wind turbine, meaning the first wind turbine was built by Charles D Brush in Cleveland, Ohio. By the year 1908, some 75 windmill turbines were being used to produce electricity between the ranges of 5 kilowatt to 25 kilowatt. Windmills to produce electricity were commonly found on farms by the 1930s in the USA.

Horizontal Axis Wind Turbines

The Horizontal Axis Wind Turbines or HAWTs house an electric energized generator and the main rotator shaft at the top of a tower. Both need to be pointed into the wind, for generation of electricity. A wind vane is usually enough for this purpose in the case of little turbines, but in the case of large turbines, a servo motor coupled with a wind sensor is used to point into the wind. The rotation of the blades is controlled by a gearbox which alters the rotational speed of the blades as and when required.
The machine is usually pointed in the upwind direction so as to protect it from the turbulence created by the tower. Many a times downwind devices are also built in a bid to combat the problem of turbulence. Such machines preclude the use of additional mechanism in order to keep the device in line with the wind; this is because the blades can be allowed to be bent during high winds.

Vertical Axis Wind Turbines

Vertical Axis Wind Turbines or VAWTs have vertical alignment of the shaft. One of the most important advantages of such turbines is that there is no need for the device to be pointed into the wind for efficacy. These wind turbines are generally used on sites that witness a variable wind direction. A wind force from any direction can be used by Vertical Axis Wind Turbines.

The presence of vertical axis means that the both the gearbox and the electrical generator can be placed near ground as there is no need for the tower to offer it support. This also means that the gearbox and the electrical generator are accessible when it comes to the maintenance of the wind turbines.

Wind Turbines - Design and Construction

The modern wind turbine is primarily used for conversion of wind energy into electricity energy. In accordance with this purpose, the wind turbine has three major components, namely the rotor component, the generator component, and the structural component. Almost 20 percent of the cost of the wind turbine is taken up by the rotor component, while an approximate 35% of the cost is consumed by the generator component. 16% of the cost of the wind turbine is taken up the structural component.

These days' environmental activists are championing the use of wind turbines, for the production of electricity as they are environment friendly and if at all, release only a minimal amount of pollutants.

It is the job of the machines to exploit the wind energy existing at a particular workplace. Designers and builders use the aerodynamic modeling for the determination of the various control systems to be employed, number of blades, shapes of the blade, and the optimum height of the tower.