Â“I donÂ’t care about how much it costs,Â” said Mr. Beaudoin, a flight attendant with United Airlines. That would be $5,000 a turbine, an expense Mr. Beaudoin is unlikely to recoup in electricity savings anytime soon.
No matter. After shoring up the roof and installing the two 300-pound, steel-poled turbines in January, Mr. Beaudoin found himself at the leading edge of a trend in renewable energy.
Fascination with wind turbines small enough to mount on a roof is spreading from coast to coast. Mayor Michael R. Bloomberg of New York last month proposed dotting the city with them. Small turbines have already appeared at the Brooklyn Navy Yard, atop an office building at Logan International Airport in Boston, and even on a utility pole in the small New Hampshire town of Hampton.
These tiny turbines generate so little electricity that some energy experts are not sure the economics will ever make sense.
By contrast, the turbines being installed at wind farms are getting ever larger and more powerful, lowering the unit cost of electricity to the point that they are becoming competitive with electricity generated from natural gas.
The spread of the big turbines and a general fascination with all things green are helping to spur interest in rooftop microturbines, creating a movement somewhere on the border between a hobby and an environmental fashion statement.
Some people have long stuck relatively modest turbines on towers in the countryside. Those are capable of generating enough electricity on a windy day to provide a fair portion of a homeÂ’s needs and can eventually pay for themselves. The new rooftop turbines are much smaller, however, and few statistics are available yet on their performance.
Mr. Beaudoin hopes to get 30 percent of his electricity from the turbines on a windy day, but whether that will happen remains to be seen.
Jay Leno, the host of Â“The Tonight Show,Â” recently installed a prototype wind turbine (as well as solar panels) atop a garage in Burbank, Calif., where he works on his car collection. He senses public interest in small-scale wind power that does not have much to do with dollars-and-cents analysis.
Â“People seem fascinated by the turbines,Â” Mr. Leno said. Â“You go, Â‘Look! ItÂ’s spinning!Â’Â”
Perched high above a building, wind turbines serve as a far more visible clean-energy credential than solar panels, which are often hard to see. At least a dozen small manufacturers have sprouted up to supply the market, though rooftop turbines still account for only 1 percent or so of the 10,000 small wind turbines that are sold each year in the country, according to Ron Stimmel, an advocate of small wind systems at the American Wind Energy Association.
That number seems poised to grow, given the recent interest.
Â“WeÂ’re prebleeding-edge early,Â” said Todd Pelman, founder of Blue Green Pacific, the maker of Mr. BeaudoinÂ’s turbine. The technology, he conceded, is not yet Â“something that would be bought at Home Depot.Â”
Mr. Pelman has sunk $200,000 of his own money into the start-up, which has just three turbines in operation Â— Mr. BeaudoinÂ’s pair, and one above Mr. PelmanÂ’s own bedroom in a Victorian house in San Francisco.
In accordance with urban sensibilities, many of the new designs are stylish. The six turbines peeping over the edge of a building in the Brooklyn Navy Yard, installed this summer, look as if they are covered with dainty white parasols, a design touch that doubles as a bird shield. The French designer Philippe Starck has plans to introduce an elegant plastic turbine in Europe this fall.
Mr. BloombergÂ’s proposal calls for wind turbines on the cityÂ’s skyscrapers and bridges, though it is unclear how big they will be and just where they will go.
Â“ItÂ’s the Wild West out there in small wind these days,Â” said David Rabkin, director of innovation, strategic partnerships and sustainability at the Museum of Science in Boston. Aided by a $300,000 state grant, the museum plans to put a total of nine turbines, of five types, on its roof by next April as an educational project.
Harvard also plans to put some atop its Holyoke Center office complex and on a parking garage. Harvard views the experimental installations as Â“outward symbols of our commitment to renewable energy and sustainability here on campus,Â” said Jim Gray, associate vice president for Harvard real estate services.
In San Francisco, another coastal city with abundant wind, the local government is considering introducing incentives to increase urban wind power.
Â“YouÂ’re seeing the birth of a movement,Â” said Jared Blumenfeld, director of the San Francisco Department of Environment, who hopes to put a turbine on his own home. Â“Ten years from now, you could probably see 2,000 to 3,000 rooftops with wind.Â”
But many experts caution that rooftops, while abundant, are usually poor places to harness the breeze. Not only are cities less windy than the countryside, but the air is choppier because of trees and the variation in heights in buildings. Turbulence can wear down a turbine and make it operate less efficiently. This is particularly problematic for houses with pitched roofs.
Â“In an urban environment, more times than not youÂ’re better off with a solar panel,Â” said Mr. Stimmel, of the wind industry association.
A recent British study of wind on home roofs found that turbines generate less power than installers projected because of lower-than-expected wind speeds. Ian Woofenden, a senior editor at Home Power magazine who teaches wind workshops, estimates that electricity from rooftop turbines may cost $1.50 a kilowatt hour or more. (That is enough electricity to run a hair dryer for an hour, roughly.)
By comparison, he said, power from a well-sited, tower-mounted turbine would cost 10 to 50 cents a kilowatt hour, and power from utility-scale wind farms costs less than 10 cents a kilowatt hour.
Â“Rooftop wind economics are abysmal, since the resource just isnÂ’t there,Â” he said in an e-mail message.
Rooftop wind advocates argue that output will turn out to be healthy in windy areas, and they also think that prices for small turbines will come down as the market grows, altering the economics.
The most established company selling rooftop turbines is AeroVironment, a California company better known for making unmanned aerial vehicles. It has installed demonstration projects on about a dozen commercial rooftops, including those at Logan airport and the Brooklyn Navy Yard.
According to Paul Glenney, director of the companyÂ’s clean energy technology center, the edge of a long, flat roof (above, say, a big-box store or warehouse) can experience up to 40 percent extra wind, much like the stiff breeze at the edge of a cliff.
Demand for AeroVironmentÂ’s rooftop turbines, which it sells for about $6,500 each, is strong, he said. Â“WeÂ’ve hidden our Web site very carefully, and yet people find us,Â” Mr. Glenney said.
AeroVironment officials say that rooftop turbines at windy sites in states with costly electricity could pay for themselves in four to eight years, but acknowledge that in places with low power prices, the turbines may never recoup their costs.
In May and June, the 20 Logan turbines combined produced just 1,430 kilowatt hours Â— less than the average home would use over that time. Airport authorities said, however, that the Boston winds pick up in the fall and winter. Mr. Leno thinks his turbine has generated about 725 kilowatt hours in six months of operation.
Â“You can say, Â‘ThatÂ’s not a lot,Â’ or Â‘Every bit helps,Â’ Â” Mr. Leno said.
British studies have recently suggested that making and transporting turbines for cities may lead to more carbon dioxide emissions than the turbines save.
A special challenge of urban turbine manufacturers is to make machines with minimal noise and vibration. At Logan, the only complaint has come from a person with an office right under a turbine.
Â“Basically he said it just sounds like heÂ’s in a Stephen King movie Â— that howling when thereÂ’s a lot of wind,Â” said Sam Sleiman, director of capital programs at Massport, the agency overseeing the airport project.
But the more common reaction to these small turbines is envy. Reino Niemela, a San Franciscan, has a direct view of Mr. BeaudoinÂ’s turbines from his backyard.
Â“I was thinking of doing something like that myself,Â” he said.