There's a growing number of small-wind turbines aimed at homeowners and businesses looking at on-site electricity generation.
Optimized for slow wind
Windtronics, based in Muskegon, Mich., later this year plans to release a wind turbine specifically designed for low wind speeds. The products will be sold as the Honeywell Wind Turbine and made available through hardware stores, although in most cases it will need a professional installer. One important feature with this turbine is that it doesn't have gears in the rotor of the fan, instead relying on power generation through permanent magnets on the tips of the blades.
There are dozens of different types of wind turbines aimed at homeowners or commercial customers interested in on-site electricity generation. As the industry matures, experts say that there need to be better tools for assessing the available wind resource at homes, which will produce an economically viable project.
Windspire Energy has developed a vertical axis turbine that can work in a variety of locations, including homes and office buildings. This is software company Adobe's corporate headquarters, where 20 turbines were installed last year at its sixth floor patio. The location works well for turbines because the towers create a wind tunnel with steady speeds around 13 miles per hour, said Randall Knox, the senior director of workplace solutions at Adobe. He estimates that each turbine will generate about 2,500 kilowatt-hours a year, which is about one quarter or a half of what a U.S. house consumes in a year.
This Wind Cube turbine from Green Energy Technologies is clearly too large for an individual home (see the truck for scale). But at 50 kilowatts of capacity, it's still considered small wind by the American Wind Energy Association, which said small wind grew 15 percent last year. These machines are designed for commercial customers in urban areas. The idea is to create a wind tunnel through the enclosure to concentrate the wind going past the wind mill so that it produces more electricity. It's one of a handful of companies, including Flodesign Wind Turbines and Optiwind, which have designs to concentrate wind to increase the speed.
One of the most popular small wind turbines is the Skystream line from Southwest Windpower, pictured here at a home in Ohio. The design is essentially a small version of the three-blade turbines used by utilities. Last month, the company released an online wind assessment tool that helps people decide quickly whether it's worth pursuing wind energy at home or at a business. Based on the location and wind map data supplied by 3Tier, it acts as a quick way to screen locations.
The Swift wind turbine, also designed for homes or businesses, has a traditional fan-like turbine design with some changes to make it quieter. The Swift has five, rather than three, blades and an "outer diffuser" ring that goes around it. That ring cuts the noise level to 35 decibels and reduces vibration, according to the company.
Helix Wind has developed a line of vertical axis turbines, which it says are rugged and well suited for gusty wind. This model, which is about 10 feet high without the pole, costs about $7,500. The permanent magnet generator can turn out two kilowatts of electricity--enough to power a portion of a home or small business. But brisk wind is required: the specification sheet notes that the generator does not kick in until wind speeds reach 8 miles per hour.
WePower makes another vertical axis wind turbine designed for homes or businesses. The annual output of its smallest grid-tied model, which is rated at 3.4 kilowatts of capacity, can deliver a wide range of electricity depending on wind speed. The company says it can produce anywhere between 2,900 kilowatt-hours and 11,900 kilowatt-hours per year. The company also sells a line of smaller turbines designed to charge batteries.