THE MODERN WIND TURBINE

Modern wind turbines sit on 210-feet to 330-feet (65-100-meter) towers. The diameter of the rotor and blades can reach more than 300 feet (90 meters).
Horizontal-axis wind turbines consist of three main parts: the tower, the blades, and a box behind the blades called the nacelle. Most of the action takes place inside the nacelle, where motion is turned into electricity. Large turbines don’t use tail fans for direction control; instead hydraulic controls orient the blades into the wind.  

In a typical design, the blades are attached to an axle that runs into a gearbox. The gearbox, or transmission, steps up the speed of the rotation, from about 30 RPM to 1,800 RPM. The faster spinning shaft rotates inside the generator, producing AC electricity. Electricity must be produced at just the right frequency and voltage to be compatible with the utility grid.