Wind

Wind energy is one of the most cost-effective and fastest growing forms of renewable energy. While small turbines that can be mounted directly on a building are being developed, the most productive installations are pole mounted systems that generate significant power and are high enough to ensure that obstructions such as trees, buildings and ground drag are not problematic.

General Information

• How much wind do I need? The U.S. Department of Energy and the American Wind Association recommends annual wind speeds of at least 10 miles per hour.
• What are the wind resources in my area? Wind resource maps, like those available from the U.S. DOE¹ , can be a good starting point but actual average wind speed may vary significantly depending on nearby structures, tree line, topography, etc. The only way to truly answer this question is to measure it with an anemometer.
• How big is a wind turbine? Systems can range from rooftop to football field size depending on how much energy you want to produce. Two primary considerations are the rotor size and tower height:
  • The rotor diameter is the circumference of the circle traced by the spinning blades. For a residential size installation, the rotor diameter would likely be less than 27 ft. Large scale turbines might be 300 ft or more.
  • Tower height depends on rotor diameter. A general rule of thumb is to install a wind turbine on a tower so that the bottom of the rotor blades are at least 30 feet above any obstacle that is within 300 feet of the tower.

Site Considerations

• The amount of energy you can produce for any given wind speed is determined by the rotor diameter. And, because the area of a circle = p r2, doubling rotor size quadruples the power output
• Because of their visibility and the turning blades, wind installations sometimes face greater challenges from abutters and local zoning boards than other types of renewable installations. It is important to work with local zoning boards and comply with local and state building codes.

Typical Costs

• The average cost is between $2-$4 per Watt, installed.
• To look up local, state and federal incentives, go to http://www.dsireusa.org/

RPM can help you navigate technical, financial and regulatory issues associated with wind turbine installations.

Remember: Efficiency first. Renewables second.

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¹RPM's Resources page includes a direct link to the DOE site.