Most of us know wind turbines generate power, and can do so in residential applications. But architects and builders need to know more: What types of homes are best suited for wind turbines; is a particular home site good for a small wind turbine; where should the turbine be positioned in relationship to the house?
These and other questions are answered for readers of Residential Design & Build by Ron Stimmel, small wind advocate for the American Wind Energy Association. But first, Stimmel reviews a few basic facts about small wind turbine operation to establish a baseline of knowledge.
Wind turbines are simple and elegant in their design, Stimmel says, with only two or three moving parts. They operate by the concept of lift and drag. “The wind turns the rotors through the process of lift and drag, which spins a magnet across a coiled copper wire, which produces current. That gets adjusted into electricity that can be used by appliances,” he explains.
For location of a small wind turbine, the more open space the better so the turbine can meet setback and permitting requirements and not conflict with public right of ways. Open space is important because it produces better wind quality. “And the height of the turbine is critical, too. The rule of thumb is at least 30 ft. higher than any obstacles within a 500-ft. radius of it. You need height to reach better wind because there is friction between wind and the surface of the Earth,” Stimmel says.
“As long as you have a tower that reaches above the house, it doesn’t matter where you place the turbine. And if half the house is covered by trees, then that will affect turbine placement on the property,” he adds.
Distance from the house is another factor to consider. The actual connection of the turbine to the electrical system is not a huge factor for architects and builders to consider, but it’s important to remember that copper wire is expensive; the farther away the turbine is from a house, the more costly the turbine will become, Stimmel explains.
“Soil conditions play a factor as well,” he continues. “If half the property is swampy or gravelly, that would be something to consider. Access to quality wind is the first priority. Then comes making sure you meet setback and zoning requirements.”
When considering turbine location relative to a home’s footprint, the decision is a personal one. The homeowner must decide whether viewing the turbine from inside the house is important or not. “I would want to watch my turbine go around while pumping clean energy into my home. I’d want to see it. Others might not,” Stimmel continues.
Built environments are not ideal for wind turbine placement because wind behaves differently around obstacles in a built environment. “It baffles turbines and causes wear and tear,” Stimmel says. Small wind turbines are sold in all 50 states. Wind resource quality can vary within a state, or within a region, so specification of turbines is done on a micro-siting basis, he adds.
Wind resource maps are available publicly through the U.S. Department of Energy, or a quick Google search will produce results as well. “Generally, if neighbors near a home site can tell a good story about how windy it is all the time, or complain constantly about it, or if you can fly a kite above the house, your site is a good candidate for a small wind turbine. Or, you can contact a local dealer installer trained in site assessment,” Stimmel says.
Myths and fears
The AWEA includes a section in its zoning guidebook called Red Herrings and Non-Issues to dispel myths and rumors floating around about wind turbines. One myth is that turbines kill birds. “There is no study that says small turbines are harmful to birds. The bird issue is raised a lot because the first wind farm in the 1980s was located in a migratory pattern. They fixed that problem years ago, and it has haunted the perception of wind power since then. In addition, when looking at the environmental impact of wind turbines, you’ll see that no water is consumed, land use is small and they create no emissions. Negative impacts are overblown,” Stimmel says.
Another myth centers around excessive noise. At operating speeds, Stimmel says, a turbine can emit some white noise like a whooshing sound, but is masked by the sound of the wind itself. “Some people raise this issue as a way to scare off wind farm developments,” he notes.
The cost of wind power
For residential sites, a small wind power turbine can cost roughly from $10,000 to $60,000 for one large enough to power the entire house. The price range reflects the different sizes available; a $10,000 model can power 20 to 60 percent of a home, while a $60,000 turbine provides more power for systems such as air conditioning and heating. “More cost equals more power, and power is proportional to turbine size,” Stimmel says.
Cost for a wind turbine might not end when it’s purchased and installed. Any energy savings gained by use of a wind turbine can be lost to an inefficient house. “The more efficient you can build your house, the less expensive a turbine will become.”
The number of tax credits relating to energy efficiency in general has erupted lately. The small wind turbine market has been without federal incentives since 1985 until the stimulus bill was passed in October 2008, Stimmel says.
“That [stimulus bill] introduced a first-ever investment tax credit for small wind systems of 100 kW and less that covers 30 percent of total installed cost. Then, the American Recovery and Reinvestment Act passed in February 2009 removed caps and lead to huge growth potential for small wind turbines. It’s a one-time credit, but any sale within eight years from February 2009 qualifies,” Stimmel says.
In addition, a patchwork of incentives is available through federal grant programs, and states might offer loans, rebates or tax credits for those who buy turbines, he continues. “It can add up to a generous incentive,” Stimmel says, “and you can use federal incentives on top of state incentives.”
WIND Turbine Resources
American Wind Energy Association
U.S. Department of Energy
doe.gov — state chapters
AWEA Permitting guide
awea.org/smallwind, click guide cover on right side