urban windpower [RE-wrenches]

[Dan Fink]

Hello Joel.

Under #1 below, I would emphasize the fact that rooftop mounting (as in
mounting the turbine *lower than* 30 feet above anything within 300 feet
in any direction) is the reason (in the first place!) that wind speeds
measure so dismally in urban areas. Also see Hugh Piggott's detailed
urban wind power debunking article:
http://scoraigwind.com/citywinds/index.htm

Under #2 below, I would mention that mounting a turbine too low also
causes undue turbulence stresses and maintenance problems on the machine
that could be avoided if mounted up at a proper height in smooth winds.

And, in general, I would stress the point that there are *no* wind
turbine designs (whether HAWT, VAWT, etc.) that can come even close to
their manufacturer's stated output ratings when mounted at rooftop level
in an urban wind regime. There's lots of hype about that out there with
VAWT designs on rooftops, but absolutely zero real numbers so far.

A 'real number' for any wind turbine means === kwh per day, month and
year. And also a machine that does not break down yearly.

DAN FINK
http://www.otherpower.com/





On Sat, 2008-02-02 at 11:10 -0800, Joel Davidson wrote:
> Windpower Wrenches,
> Please review my short reply to inquiries for urban windpower. Any changes, 
> corrections, additions? Thank you for your help.
> Best regards,
> Joel Davidson
> 
> 1. Wind power is proportional to the cube of the wind speed. Wind generators 
> start producing power at 7 mph wind speed and produce maximum power at 30 
> mph. At 15 mph wind speed, power produced is 1/8 maximum power. The average 
> wind speed for Los Angeles is 6 mph. Average wind speed in most urban areas 
> is under 10 mph. See http://www.bwea.com/ref/faq.html
> 
> 2. Buildings and tower height and noise levels are governed by zoning 
> ordinances. Buildings under wind generators and buildings and trees near 
> wind generators create turbulence. At 30 feet above the ground and away from 
> all obstacles, wind speed is 1.5 times faster than at ground level. At 100 
> feet, wind speed is 2 times faster than at ground level. See 
> http://www.bwea.com/you/siting.html
> 
> 3. Wind generator towers on buildings must be securely fastened which causes 
> transfer of vibration and noise to the building.
> 
> 4. Small wind generators are generally low voltage (12, 24, 48) battery 
> chargers as compared to batteryless utility interconnected PV systems.
> 
> 5. Paul Gipe, wind consultant, is less than optimistic. See 
> http://www.wind-works.org/articles/RoofTopMounting.html
> 
> 6. Additional urban wind info:
> http://www.esru.strath.ac.uk/EandE/Web_sites/01-02/RE_info/Urban%20wind.htm
> http://www.britishgasnews.co.uk/index.asp?PageID=16&Year=2005&NewsID=670
> http://www.timesonline.co.uk/article/0,,2090-1603098,00.html
> http://www.psfk.com/2005/05/roof_mounted_wi.html 
> 
> 
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