Wind Turbines

• Wind turbines are machines that turn the kinetic energy of the wind into electrical energy, usually for commercial consumption. Most modern wind turbines feature large rotating blades housed atop a tall tower. The rotation of the blades turns a gear shaft connected to an electrical generator, thus creating electricity.
  
  

Placement

• Given that wind turbines rely on an often unpredictable source of power, the wind, great care must be used in deciding where they are built. Wind resource assessments are used to estimate how effective a given area will be in producing energy. These rely on a combination of measurements taken at the site and the results of computer modeling. Sites with strong, regular wind are preferred.
  
  

Blades

• Modern wind turbine blades are usually made of fiber-reinforced epoxy, and are thus both light and strong. This means they can accelerate quickly to take advantage of increases in the wind speed. On small wind turbines a wind vane is used to ensure the blades always face into the wind; on larger turbines a combination of wind sensors and servo motors is used instead. There is turbulence behind a turbine's tower, so they are usually constructed such that the wind hits the blades before reaching the tower.
  
  

Electricity

• Basic turbine. (Image by author.)
  
  The rotating shaft of the turbine connects to a gear transmission that powers a second, high-speed shaft. This provides the rotational force to an electrical generator, which in wind turbines is usually an induction generator that produces alternating current. Almost all types of power station take advantage of electromagnetic induction, whereby a conductor in a moving magnetic field produces voltage, and this is the principle used in wind turbines.
  
  

Tower

• Wind is stronger at higher altitudes because there is a drag effect close to the surface of the land or ocean; for similar reasons wind is also more turbulent closer to the surface. It is therefore advantageous to place the turbine atop a tower so that it receives the best wind. Modern wind turbine towers are usually made of tubular steel sections, are about 70m tall, and can bear loads of more than 400 lbs. Given the weight of the tower and turbine, and the force of the wind upon it, the tower must be securely fixed, usually to strong concrete foundations.