• Windmills have been in use for hundreds of years.windmill image by Bruce Allinson from Fotolia.com
  
  Windmills have been in use for many centuries as wind is a renewable source of energy. Originally used in the 1200s for tasks such as draining water or grinding grain, windmills became useful for a myriad of other things with the development of the cam shaft and crank shaft; when combined, these shafts give windmills lifting power. When considering windmills it is important to ask such questions as how wind energy works and what types are available.
  
  

How Does Wind Energy Work?

• Windmills, or the wind machines manufactured today, use blades to capture the kinetic energy of the wind. As the wind courses over the blades it creates lift, causing them to turn. The turning blades are connected to a drive shaft which turns an electric generator and creates electricity. Wind power use has been growing quickly.
  
  

What are the Different Types of Windmills?

• Early types of windmills include drain and meadow mills, used to drain water, as well as open and closed post mills that were used for grinding. The Dutch sawmill was designed exclusively for sawing wood.
  
  The most advanced type of windmills are wind turbines. A common type is the horizontal axis wind turbine, or HAT, which has two or three blades that turn perpendicularly to the wind direction and an axis positioned horizontally in the wind direction. The VAT has vertical axis turbines that do not rely on the direction of the wind. Both of these types of windmill rely on the lift principle, and the aerodynamic qualities of the blades allow them to reach a higher speed than that of the wind.
  
  

What are the Benefits?

• Environmental concerns, such as emissions generated from fossil fuels, have led to a substantial growth in the use of wind power in recent years. It is associated with significant environmental benefits as windmills and wind turbines do not burn harmful fuel and do not produce water or air pollution. Wind is both a clean fuel and an economical resource of power.
  
  

What are the Disadvantages?

• Windmills can have an adverse influence on bird populations in the wild as it is possible for them to fly into and get entangled in the large blades. Some individuals also find them to be blemishes on otherwise beautiful landscapes.