A wind turbine is a machine for converting the kinetic energy of an air flow into mechanical energy.  The mechanical energy is most frequently used to drive an electric generator but can alternatively be used to drive a variety of other loads such as a pump, a grinding stone, etc. 
The prior art is replete with various wind turbine designs.  They typically include a rotor assembly including two or more blades, a shaft for transferring rotational energy from the rotor assembly to an electric generator, and a housing generally including a gear box, the electric generator, and an electronic controller.  The rotor assembly and housing are typically mounted on a tower to provide sufficient elevation to best expose the blades to the local wind and to assure proper ground clearance.  A yaw controller is generally provided to optimally align the rotor assembly relative to the wind direction.