Major components of windmills and wind-powered turbines include a rotor, tower, gear box and a weather vane. Traditional windmills power pumping equipment or milling components while wind-powered turbines make use of a generator to produce electrical current. Windmills may have either a vertical or horizontal axis depending on their environment and intended use.
Vertical axis windmills were popular throughout history but inefficiencies in the design led to rise of horizontal axis designs. Horizontal designs utilized a large upright post to mount the body of the mill and the structure was commonly elevated using brick or stone to prevent rot. Horizonatlly-mounted post mills had four blades connected to a central post and provided the power needed for water pumping, grinding or even hammering activities.
Tower mills offered more efficient performance by utilizing a rotating-cap design mounted to a brick or stone tower. This layout allowed for taller structures and provided superior weather resistance than vertical designs. Modern electrical turbines consist of a nacelle attached to a tall narrow tower that is typically between 150 and 200 feet tall. This nacelle contains an electrical generator powered by three or more wind-driven blades. Turbines attach to a base made of concrete reinforced with steel bars and typically rotate about 20 times per minute.