The state's midsection isn't windy enough to justify harnessing wind on a commercial scale. But for those who just want to supplement their power supply, one potential solution is the Windspire, with its comparatively low price tag and a design that works on office rooftops and in suburban open spaces.

The mechanism can be seen on the N.C. State University campus, where one of three Windspires in the state converts wafting Carolina breezes into electrons. Executives with Blue Sun Renewable Energy in Washington, N.C., the turbine's mid-Atlantic distributors, say several more Windspires could be installed in the state in the coming months.

"You have to look at this as one of the first entries into the renewable energy market that's completely affordable for ordinary people," said Jeremy Peang-Meth, a Blue Sun partner.

A Windspire unit costs $6,500. Installation can add another $4,000 and requires building a cement foundation for the 624-pound apparatus. In North Carolina, however, the cost of the unit is marked down by more than half if the buyer takes advantage of federal and state tax incentives for green energy.

There are other small wind turbines on the market, but the Windspire has enjoyed a promotional boost since being featured on episodes of ABC's "Extreme Makeover: Home Edition" and "20/20" in recent months. The Graveyard of the Atlantic Museum in the Outer Banks and Lem's Auto Sales and Motor Sports in Shelby, west of Charlotte, are both considering installing one. Windspire units already are generating power at a sustainable community under development by Blue Sun near Edenton and at a private home in Jamesville, east of Rocky Mount.

But questions remain about its long-term prospects. The National Renewable Energy Laboratory in Colorado stopped a test of a Windspire last year after the turbine broke apart when welded areas failed.

Mariah Power in Nevada, the company behind the Windspire, said it has fixed all the defects in the prototype that was tested by NREL and the Windspire hasn't experienced problems since. According to Blue Sun, more than 200 units are in use around the country, including the U.S. Botanic Garden in Washington, D.C., and, the Marin County Convention Center in California.

Brian Miles, a wind energy extension specialist at the N.C. State's Solar Center, said that pending further tests, the Windspire is "not quite ready for prime time" but nevertheless looks promising.

"The big thing going for this one, quite honestly, is they've been diligent about doing third-party verification," Miles said. "A lot of these products make outlandish claims, or even normal claims, that are totally unverified."

A bite out of your bill

According to Mariah Power, the 1.2-kilowatt Windspire can cut household energy use by 25 percent in an area where wind speeds average 12 mph. The average wind speed in Raleigh is about 9 mph, which means that the Windspire would likely provide between 5 percent and 10 percent of a typical household's energy in this area, Miles said. But the results will depend on wind factors, which can vary across the state, and even from one end of a county to another.

The Windspire's energy potential in Raleigh is about to be put to a test.

NCSU has had its unit since April and will begin measuring power output soon.

And officials at the planned Centennial Science Center at NCSU expect to install four Windspire units for testing on the roof of the building when construction is completed next year. Ewan Pritchard, program director at the university's Advanced Transportation Energy Center, is reviewing the Windspire for the building and says that so far it looks like the most promising small-scale wind turbine, especially for areas like Raleigh that have poor wind resources.

The other selling point of the Windspire is that it's virtually noiseless. George Bates had two installed in his Chesapeake, Va., home last month, and he says they are inaudible. "It's just an incredible piece of equipment," Bates said.

Jeff Cooper had a Windspire installed this month at his home in Jamesville.

"If it does away with even one light bill a year, that's great," Cooper said.