Publisher Summary A large amount of power is contained in the movement of air in the form of wind. The mechanical devices that are used to convert kinetic energy in the wind into useful shaft power are known as windmills, wind machines, or wind turbines. The advantages of using wind energy are: it does not deplete natural resources; it is nonpolluting, making no demands upon the environment beyond the comparatively modest use of land area; and it uses cost-free fuel. These advantages must be weighed against the disadvantages: wind is an intermittent source of energy and the total system costs are high when an energy storage system is included. The cost of wind generated electricity is now comparable to the average cost of generation from conventional sources. Wind-electric system (WES) is a wind machine and an electric generator.