How Windmill Power Works
Windmills capitalize on the movement of air currents across the uneven surface of the earth as it heats up and cools down. Dry land heats up faster and cools down faster than the oceans. Areas closer to the equator receive more of the sun's energy than the North and South Poles.
The atmospheric convection that results from this uneven heating creates air movement that can be harnessed by windmill designs using either a horizontal axis or vertical axis turbine. The more common horizontal axis turbine design uses three blades shaped like propellers to capture the wind that blows over the propellers to rotate them. The blades are connected to a drive shaft, which is connected to a generator with cables that connect to the building(s) being powered. As the blades rotate, the drive shaft turns, and the generator converts mechanical energy into electricity, which travels along the cables to the buildings.
As windmill design evolves, it has become easier for those motivated to "Do-It-Yourself" (DIY) to build a windmill for under $200 using sheet metal, metal tubing, car battery (24-to-48 volts), and electrical wiring
all typically found in hardware stores.
The advantage of windmill energy is that it's sustainable and inexpensive to produce. The challenge is that the windmill must be built in a location where the wind regularly blows fast enough to keep the windmill moving. Suitable locations include open areas like shorelines or vast plains, tops of hills or gaps in mountains that act as funnels for wind.
For those needing a bit more guidance, you can purchase kits complete with plans and components, making it even easier for homeowners to build small windmills. These 100-kilowatt windmills provide sufficient electricity to power a small farm. A link to Earth4Energy.com, one company selling plans and kits is cited in the references at the end of this article.
Larger blades and turbines have also been built that will generate many megawatts of energy. Typically these larger turbines are built in groups, sometimes called wind farms. One wind farm in Texas uses 421 windmills to power over 200,000 homes year round.
Although windmills have been used for thousands of years, they have recently regained popularity as people look for clean, affordable, sustainable alternatives to energy generated from fossil fuels. Government tax breaks are now offered to people seeking to build windmills, encouraging greater investment. Producers of wind energy are usually private citizens or businesses, known as "Independent Power Producers," who are often able to sell excess electrical power to the public utility companies, who own the fossil-fuel power plants.
Here are some additional resources which provide more detailed information on how to build your own windmill, the basic design of windmills, and the history of the development and application of wind-power around the world.
1. To Make Your Own Windmill http://makeyourownwindmillnow.blogspot.com/2008/07/make-your-own-windmill-reduce-energy.html
2. The American Wind Association, Wind Web Tutorial
3. The Global Wind Energy Council (http://www.gwec.net/)
4. FPL Energy, Plant Fact Sheets (http://www.fplenergy.com/portfolio/wind/plantfactsheet.shtml).
5. U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy (http://www1.eere.energy.gov/windandhydro/wind_how.html#sizes)