Windmills and Design Issues

Number of Blades

• The number of blades on a windmill design can vary and will depend on many factors. Windmills tend to have an odd number of blades as this makes for a much more stable design than even numbers would. Windmills with even-numbered blades can suffer from vibrations. Alternatively, the more blades on a windmill, the easier it is to start in low wind conditions. However, more blades also create more noise. Most windmills have found a balance using three blades, as this is not too noisy, has good energy efficiency and is not too costly.

Tower Height

• The height of the tower will affect the amount of power produced from the windmill as well as the efficiency. The height of the tower must be great enough so that the blades are at least 30 feet from any nearby structures, such as trees or buildings. You actually want to avoid any such structures as much as possible. Many areas will also have height restrictions in place that you must abide by. Finding a tower height that meets local regulations and produces plenty of power can be a difficult task and will first be addressed in the design phase.

Location

• The location of the windmill is one of the first design issues to work out. You want to choose an area that gets plenty of wind and is not obstructed by trees or other buildings. Many windmills and turbines are placed on top of hills. Collect wind information from the local weather stations; airports will also have some information on local wind conditions throughout the year. Look at these maps to find a good windy spot near you. You can also hang logging anemometers in different places to find the spot with the best wind.

Power

• Determine the type of power you want produced and what you will do with it in the design phase. The power from windmills can be transformed into a direct current or alternating current. Which current you need depends on how you will use the power. A windmill can have batteries or be hooked up directly to the electrical grid of your home. The different power connections require different designs and must be taken into account before you start building. In particular, the electrical company will need to approve all plans if you are connecting a windmill to the electrical grid.