The Skystream wind turbine, made by Southwest Windpower, is mounted on the roof of the Museum of Science in Boston. Credit: Museum of Science
David Rabkin, Farinon Director for Current Science and Technology at the Museum of Science in Boston, stands on the museum's roof with the Proven 6 wind turbine that is yet to be installed. Credit: Museum of Science
A single blade of the Skystream wind turbine at the U.S. Botanic Garden in Washington, D.C. Credit: Franklyn Cater/NPR
A Southwest Windpower field engineer works on the Skystream wind turbine at the U.S. Botanic Garden. Credit: Franklyn Cater/NPR
Phelps Architecture, Construction and Engineering High School in Washington, D.C., recently installed two Windspire vertical wind turbines to provide clean energy to the school. Credit: Mariah Power
When most people think about wind power, a vast field of gigantic turbines spinning on a ridgeline might come to mind. Well, that's big wind.
But another part of the wind power industry is thinking small — as in turbines that are the right size to power a single home or business. And one of the hottest ideas blowing around is the concept of roof-top turbines that generate energy right at the point of use.
One Essential Ingredient
Reno, Nev.-based Mariah Power makes a turbine called the Windspire. And one of these skinny, 30-foot-tall turbines can be found in the heart of Washington D.C., at the foot of Capitol Hill. It's in front of the United States Botanic Garden — and the gardens' conservation horticulturist Ray Mims came up with the idea to put it there for an exhibit on sustainability.
"People think it's a kinetic sculpture," Mims says. "[It] doesn't look like a typical wind turbine or windmill."
There are actually two turbines at the botanical garden — the Windspire and a Skystream, made by Flagstaff, Ariz.-based Southwest Windpower. The Skystream looks like a big fan on top of a very long pole.
Framed on a recent morning by a cobalt blue August sky and the Capitol dome, the turbines are striking. But the turbines weren't turning at all.
And that's one hitch — a minimum wind speed of 12 mph is an essential ingredient for getting these creations to do their work. A problem with the turbines' location at the botanical garden is that they are at the bottom of a hill — not the windiest spot.
Mims says the gardens' turbines nevertheless turn about 75 percent of the time. But he says they're only offsetting a tiny portion of the facility's total energy use — less than 1 percent.
As Common As A Light Pole
So, if putting turbines on the ground at the bottom of a hill is less than ideal, what about putting them up higher? Say, on top of a building?
That's the urban small-wind vision of Mariah Power's CEO Mike Hess.
"I want to make the product ubiquitous, so we see it all over — on top of skyscrapers, right on a lamppost driving the lights on the street," Hess says. "You can put them in any number of places, and they become like the light pole or the power pole."
Slowly, Hess' vision may be becoming a reality. His company is selling 20 roof-top turbines to Adobe, the software company in San Jose, Calif. And this month in Portland, Ore., a set of four Skystream turbines were installed on top of a new office tower.
Five kinds of turbines can now also be seen on the roof of Boston's Museum of Science.
"This project started with people like me standing on the roof of the museum and saying, 'Dang! It's windy up here, we ought to be able to get a lot of free power,' " says David Rabkin, Farinon Director for Current Science and Technology at the Museum of Science in Boston.
Rabkin says his team studied wind patterns for a year before they set up their rooftop "wind lab."
"We need to reduce our carbon footprint," he says. "So the initial goal was to take advantage of those gobs of wind that are coming right past us all the time and see if we could significantly reduce the amount of power that we pull off the grid and replace it with nice clean wind power."
Rabkin says this $300,000 project, including all the permits and custom engineering, is really just an experiment — paid for by donors. He's not expecting a lot of power.
"If we do well, we'll generate about enough electricity to power three suburban homes," Rabkin says.
And the amount of power used by three suburban homes is a very small fraction of the museum's overall energy use.
"A homeowner might do it on the ground, but a business with them mounted on top of their structure — if they consume energy like we consume energy — they're not going to make a big dent in it," Rabkin says.
Small Wind A 'Folly'?
Alex Wilson, who started a publishing and consulting company called BuildingGreen, has been a longtime proponent of "big" wind power.
"I'm a huge fan of wind power," Wilson says. "I have been for years, for decades."
But while he's an advocate of big wind, he says he's become disenchanted with small rooftop wind power. He's even written an article called "The Folly of Building-Integrated Wind."
Wilson says the air around buildings is too turbulent, and there is no steady stream to power the turbines. The noise and vibration from turbines can also be a problem in urban settings. And he has big questions about whether small turbines that generate only a few kilowatts are worthwhile.
"The Achilles heel of building integrated wind is economics," Wilson says. "There's a huge economy of scale with wind power ... it's hard to be cost effective with small turbines. And when we put them on top of buildings, the cost goes up and the performance goes down."
In Wilson's mind, solar power — for the time being — beats wind power in the urban small-scale setting.
A Maytag Guarantee
Mariah Power's Hess says he's sensitive to Wilson's concerns.
"Some of the over-promise and the over-commitment that was made early in the life of small wind has come back to hurt," Hess says.
But if people don't hold such high expectations, Hess believes they will be pleased with his product — or he guarantees their money back.
"If I can be the Maytag of wind turbines, I'm going to be a very happy camper going forward," he says.
His company is getting a lot of help, including $3.2 million in federal stimulus dollars. This money is being used to fund production and create jobs at a former auto parts plant in Manistee, Mich.
There are also federal and state incentives for small turbine buyers. So if consumers pay $8,000 to $15,000 for one of these smaller models, they might get a few thousand back.
But if that's the cost for putting one on the ground, making sure it won't blow off a roof in a hurricane costs a lot more.
There seems to be general agreement: If placed on the ground, in an area with good, steady wind, a small turbine should pay off, although it might take five to 10 years — or more.
As for turbines that dot city roofs like chimneys or TV antennas, Wilson says maybe he can still be convinced.
"There may be a system that comes along, the better mousetrap, that actually solves all the concerns," he says. "I'll be the first to get behind that and to be very excited about that."
But folly or no, the small wind industry is claiming big growth.
The American Wind Energy Association says more than 10,000 small turbines were sold in the U.S. last year. And they're projecting exponential growth in years to come.