With the help of two to three blades, wind turbines capture wind high up rather then on ground level to help generate electricity. On the downside of the blade, a low air pressure pocket is caught, and this is what helps to pull the blade backwards in turn causing the rotor to turn. This is called lift. The lift is stronger then that at the front side of the blade, called drag. This combination of lift and drag makes the rotor turn and causes the shaft to turn, which leads to electricity.
Wind turbines are useful as single units, in a power grid or even connected to a photovoltaic system.
Single turbines are generally used for water pumping and communications, whereas farmers and home owners in windy areas use them to generate electricity. Several electricity providers now though are getting more and more aware of the crisis we have on our hands and are turning to alternate methods to generate electricity eg: wind turbines to provide for their customers.
Wind turbines can be divided in two major sections: horizontal-axis turning turbines and vertical-axis turning turbines.
Horizontal axis turning turbines are the most commonly type of turbine used today as they are easy to assemble and generate more power. They consist of a tall tower, a rotor that can either face the wind or away from it, a generator, the controller and others. They mainly have two or three blades. It mostly depends on the model you buy and how many you want.
Vertical-axis turning turbines though on the other hand, are divided into again 2 categories: the Savonius which was first invented in Finland is an S-shape if viewed from above and turns slowly but has a high torque. This type of turbine is mainly used for grinding grain, pumping water and other day to day farm tasks but its one flaw is that its slow rotational speed makes it bad for generating electricity.
The other type of Vertical-axis turning turbine is called the Darrieus. This turbine was first invented in France in the late 1920’s. It is often called the egg beat turbine as it has blades rotating in and out of the wind using aerodynamic lift. Strangely enough this turbine creates more electricity then the drag devices.
Windmills have been used by humans since they say 200 B.C for grinding grain and also pumping water. They then went on to be used on a farm and pump water and generate electricity.