sierraclub.org - sierra magazine - march/april 2013 - innovate-wind-turbines - innovate: look ma, no blades!
By David Ferris
Illustration: Brown Bird Design
The bulbous, chimneylike Sheerwind Invelox works not by reaching for the sky but by accelerating and concentrating air at ground level. It captures low-speed wind coming from any direction and funnels it into a 40-foot-wide tube. The tube narrows and takes a 90-degree turn, causing the breeze to accelerate; a 10-mph wind could reach 40 mph—plenty of velocity to spin an electricity-generating turbine.
Wind Catcher
Daryoush Allaei grew up in Abadan, Iran, where a breeze off the Persian Gulf, 33 miles away, sometimes delivered relief from the hot summers. While the smokestacks of one of the world's largest oil refineries distinguished the skyline, Allaei was more impressed by far older Persian structures that looked like chimneys but served an entirely different purpose: the neighborhood wind catchers.
Allaei's grandfather had one of these wind catchers, which captured sea breezes and piped them to the basements of homes. The cool air would circulate upward and make the interior temperature bearable.
As an adult, Allaei immigrated to the United States and earned his Ph.D. in mechanical engineering, with a specialty in controlling industrial noise and vibration. At one point, he evaluated a big commercial wind turbine, and he puzzled over its top-heavy design. "These turbines sometimes weigh over 150 tons and are 100 or 120 meters [328 to 393 feet] high. It didn't make sense," says Allaei, 56.
In a parking lot next to his office at Sheerwind, in Chaska, Minnesota, Allaei is building the Invelox, a next-generation wind harvester (see above). His 90-foot-tall device could create the same amount of power as a 1.8-megawatt commercial wind tower, but at a third of the height, on a seventh of the land, and with a turbine more than eight times smaller in diameter. And he says the electricity would be at least 40 percent cheaper, partly because the air chamber cranks up in the faintest of breezes—even those less than two miles per hour, which is a quarter of the wind speed needed to drive a traditional turbine.
Allaei has proposed a collapsible aluminum-and-fabric model that could be air-dropped and assembled at military outposts or in disaster areas. Another version could be built as part of a commercial building, its ducts installed the same way that HVAC machinery is now.
It wasn't until he was well along in designing the Invelox that Allaei realized he was updating the wind catchers of his youth. This time around, though, the power could help retire those fossil fuel refineries for good.
This article was funded by the Sierra Club's Beyond Coal Campaign.