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Lessons That Matter
So, what can we take from all of this? The lessons are pretty straightforward:

.   Swept area determines how much of the wind’s power your turbine can extract. There is no way around the mathematics of your collector size.

.   Wind turbines exposed to laminar winds generate more useful amounts of electricity. Wind turbines sited in turbulent locations (on buildings, or at or below tree level) cannot—and will not—generate much, if any, electricity. There is no way around the physics of fluid dynamics.

.   The 30-foot tower height rule helps determine whether the wind turbine will be exposed to quality winds over the life of the system.

.   Siting your wind turbine upwind in the direction of the prevailing wind will minimize turbulence.

The economic payback in a wind turbine is directly proportional to the electricity it generates over its life. If a wind turbine is sited in turbulent winds, it simply will not generate much electricity, making it a questionable investment. In addition, the turbulence will cause increased wear and tear on the turbine, shortening its useful life. But a wind system includes more than just the turbine—it includes a tower that’s properly sized for the site, foundation, wire run, balance-of-system components, all labor and materials for installation, and various other costs.

People take care of investments when they make sense. Wind system owners invest maintenance and repair dollars in things that work, like a properly sized and sited wind turbine. Owners quickly abandon ideas that don’t work. The history of small wind tells us that rooftop wind turbines and wind turbines installed on towers too short for the site are quickly abandoned and become derelict once they need repair. Simply put, they were bad investments. A $20,000 wind-electric system that only lasts for two years is a poor investment compared to an $80,000 system that lasts 20 years.

Which Wind Turbine?
If you are shopping for a wind turbine, where do you go for help? Three organizations host websites with recommendations based on equipment that is certified to an American National Standards Institute standard, actual performance test results, and industry feedback.

The Small Wind Certification Council (SWCC) is a certifying body that confirms that published turbine test results conform to the American Wind Energy Association’s 9.1-2009 Small Wind Turbine Performance and Safety Standard. Turbines that are certified to have met the AWEA 9.1 criteria are listed at smallwindcertification.org. Make sure you peruse the list of SWCC-certified turbines, not the applicant turbine status.

The Interstate Turbine Advisory Council (ITAC) is a consortium of state public-benefits programs that fund the installation of renewable energy systems. They publish the Unified List of Wind Turbines (at bit.ly/ITACturbines) that participating state programs may be willing to fund.

Intertek is another organization that certifies wind turbine test results to the AWEA 9.1-2009 standard. However, this website (bit.ly/IntertekDirectory) is a bit more confusing since Intertek certifies components as well as entire wind turbines.

If the wind generator you are considering is not on one of these three lists, move on. Or at least understand that you are making a risky purchase of an untested, unproven design, and be ready to accept the outcome of your speculative investment.

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Mick Sagrillo consults, teaches, and writes about wind power. He and his wife have powered their house with wind for 32 years, and Mick has flown dozens of models during that time.

Downloadable wind roses • bit.ly/NRCSWindRose

Article Written by, Mick Sagrillo

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