All images via Building Green
Everybody loves integrated wind power, like this big turbine at the Bahrain World Trade Center, but does it actually work? Or is it just there to make a green statement? Alex Wilson of Building Green doesn't think much of it, and calls it "folly."
There is no question that they do make a green statement, visibly spinning while photovoltaics just sit there. But do they actually do what they say?
1. The air is often turbulent.
Buildings change the wind, bouncing it around, where wind turbines work best with steady air, what they call laminar wind.
According to Ron Stimmel, the small wind technology expert at the American Wind Energy Association (AWEA), this turbulent flow confuses a wind turbine, affecting its performance. "Even if it feels really windy [on top of a building], it's probably more turbulent than steady wind," he said. A common rule of thumb, according to Stimmel, is to elevate a wind turbine at least 30 feet (9 m) above anything within a 500-foot (150 m) radius, including the building itself.
2. Noise and Vibration can be a problem
In one of the only extensive surveys of actual performance of building-integrated wind turbines (the Warwick Wind Trials Project, the only turbines able to generate close to their projected electricity output were mounted on high-rise apartment buildings. And these wind turbines remained switched off throughout most of the test period because of complaints from the residents about noise.
If you try to put a turbine on a tower on top of a building—to get away from the turbulent flow and into the most productive wind—the stresses on the building are magnified. Randy Swisher, the past executive director of AWEA, notes that wind turbines are subjected to a great deal of stress, and if installed on a building, "that stress can be transmitted to the building structure, creating substantial problems."
Blades do occasionally fly off. In the country that is less of a problem, but in the blades on the Bahrain Trade Center are over forty-five feet long.
4. Poor measured performance
Few people actually say how much power they are actually getting.
Despite the growing number of building-integrated wind turbine installations around North America and the rest of the world, obtaining actual measured performance data is like pulling teeth. Most manufacturers of these wind systems either claim not to have such data or are unwilling to share it. The reason for this reluctance may be that actual electricity production is much worse than expected.
A British study looked at 26 building mounted turbines and found that promised power exceeded actual production by a factor of fifteen.
With the worst-performing systems, the electricity required to run the electronics exceeded the electricity production, so the wind turbines were net consumers of electricity!
There is a lot more, but Alex concludes:
I want to like building-integrated wind. There's a wonderful synergy in the idea of combining form and function by generating electricity with turbines that reach into the sky on the buildings they will help to power. But in most cases, at least with today's technology, it just doesn't make sense....
By all means, power your buildings with wind energy, but do it on a larger scale, remotely, where the turbines can operate in laminar-flow winds and where their vibrations and noise won't affect buildings and building occupants.
Interesting reading at Building Green.
More on building integrated wind power:
New Turbine Design Wins Sustainability Award
New Online Small-Scale Wind Turbine Power Calculator Tool Launched by Carbon Trust
5 Good Ways to Get Green Power Into Your Home
Treehugging Turbine is Totally Tubular
CES 2009: Solar and Wind Hybrid Charger from Kinesis Industries (Video)
10 Small-Scale Wind Turbines Cut NYC Apartment Building's Electric Costs in Half
Windspire Vertical Axis Wind Turbine Wins PopSci Award, Maker Opens New Factory