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Allright, I just re-roofed the primary house & doubled the number of those round turbine "vertical" whirleygigs (to pull/vent this hot Texas summer heat out of our attic!).
Now I cant help but watch those silver puppies out my kitchen window, just spinning like crazy 24/7! Seems to me we could very simply harness all that great energy that is currently just blowin' in the wind?
Can one of you E.E. wizards please dumb this down & show us laymen how we might go about retrofitting one of these rooftop gems with a light-duty, inexpensive generator system so we can all start harnessing that wind & make our utility meters slow down a little (or just charge our 12v's)?
Thank you so much in advance for any and all help here!
 

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If your area has a good constant wind you would be better off to put up a standard wind power setup. It could mount to your roof or to a proper free standing tower. You can see how you area might fare for potential wind power by finding the average wind speed charts for your location. Many Wind power web sites have these provided for you.

Your attic ventilators do not have the design characteristics to be usable for producing any power. They do what they are supposed to do which is to vent hot air from your attic. You would not want to slow their functioning down by attaching anything to them.
 

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I've done a little researchinto wind power. I am not any sort of mechanic or scientist by any means. But the rooftop wind generators should not be, on the roof. Mount a tall one in the ground next to the house, but not on the roof.You would need large trusses of steel to take the force of wind that would collapse your house.

There is a new company that is selling stocks right now (which I'm not buying), but their product looks VERY fascinating, and that's for a vertical axis wind generator supposed to be in the marketplace this year. Looks like the smartest design yet. Those huge, giant blade turbines are obnoxious and take up vast amounts of real estate. These don't do that, and one can create a lot of power.
 

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wind power can be produced from any size turbine you choose. It aint got to be big. It aint got to be heavy. It wont cause your house to fall if it weighs less that a buick. Find out what your needs are, what you can afford, what your skill level is and get out there and build something. A wind roof exaust turbine is a fine idea. Just figure out how to make it work.
 

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Allright, I just re-roofed the primary house & doubled the number of those round turbine "vertical" whirleygigs (to pull/vent this hot Texas summer heat out of our attic!).
Now I cant help but watch those silver puppies out my kitchen window, just spinning like crazy 24/7! Seems to me we could very simply harness all that great energy that is currently just blowin' in the wind?
Can one of you E.E. wizards please dumb this down & show us laymen how we might go about retrofitting one of these rooftop gems with a light-duty, inexpensive generator system so we can all start harnessing that wind & make our utility meters slow down a little (or just charge our 12v's)?
Thank you so much in advance for any and all help here!
I get your idea, and have been trying to get hold of a free/cheap one of these units for a couple years for experimentation; just not too common in my area with all the snow I guess.....I think its a fantastic idea. Its spinning anyhow, why not spin something useful.

Any chance you could get some pictures of yours from the attic side, I'd love to see how one works. Any shafts available to hook on to?
 

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Lamar i've had that same idea when i saw those things, but i thought maybe that the generator might cause a little too much drag for it to produce any useable electricity.

With a plug-in power converter, you can maybe trickle some electricity into your house to lower your bill, but i doubt they would actually power anything by themselves.

They may be able to slowly charge batteries though....or possibly run LED lights....
 

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The power a wind turbine will extract is related to the area of the turbine and the wind speed, plus an efficiency factor since no turbine is 100% efficient.

There's a good table relating power (watts) to wind speed (mph) and turbine area (square feet) at http://www.ndsu.edu/ndsu/klemen/Perfect_Turbine.htm

A few data points ...

5 MPH wind, "good turbine" (for efficiency) will deliver 0.2 watts per square foot of swept area.

10 MPH wind, 1.75 watts per square foot

15 MPH wind, 5.9 watts per square foot

As a guess, a typical rooftop exhaust vent turbine will have an area of 1 or 2 square ft. Let's say 1.5 square ft.

Since the power produced is not linear with wind speed, multiplying these numbers by the average wind speed will not produce accurate results. Fortunately, the referenced web page has calculated monthly energy production using a Rayleigh distribution of wind speed.

If the average wind speed is 10 MPH, which may or may not be representative of your location, you will generate 2KWH a month of electricity with a "good" design turbine per square foot of turbine area. (There's a map of estimated wind speed for the US at http://www.windpoweringamerica.gov/pdfs/wind_maps/us_windmap.pdf. However, the wind speed data is for 50 meters (165 ft) above ground level, and typical house height wind speed will be much lower unless you live on top of a tall ridge.)

We've assumed 1.5 square ft for the projected area of a typical roof ventilation turbine, so that's 3 KWH per month for one turbine, hooked to a generator.

Here in northern Virginia, we pay a bit under 10 cents/KWH for power from the NOVEC co-op that serves our area.

So, you would generate 30 cents worth of electricity a month based on all these assumptions. Feel free to plug in more accurate numbers.

In my view, the only reason to make a turbine generator at this scale would be for amusement; it certainly is not a cost effective way of generating anything more than a trivial amount of electrical power. A small solar cell array would be more useful.

Jack
 

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I would start with one of those small DC motors you find in toy cars.

A shaft system shouldn’t be too hard to set up.
You could even mount the whole thing inside the “ball” of the turbine.
(It stays dry in there even in the rain.)

I agree it will not be a lot of juice but it is 24/7 and should be enough for small battery charging.

It would be a neat project.
And it would be very stealth.
 

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Hummm, l kinda looking at that map my area apparently aint too good for wind power. Oddly enough I have a small one thats only mounted about 30 ft in the air and it produces a decent amount of power about 1/3 of the year.

The biggest problem I see with someone putting up a tower much of any size that would be benefical on their property unless in a rural location is you can bet a couple of neighbors and city code enorcement would most likely have a problem with it creating major head aches for you and possibly wasting the money you invested in the system.
 

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stupid question

So when it's real hot does the hot air rising through those turbines accelerate their speed?
I read an article years back about University of Arizona building this black painted chimney that was heated by the sun. The draft created by the heat rising through it was used to pull air through a building. It was quite a draft and it was discussed about the possibility using the draft to power a small generator.
Lost track of the article many computers ago but just wondered on the feasibility of making something to try it out.
Don't know the math on how high, diameter velocity and such..
Just thought I'd throw it out there.
 

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You may find this interesting . . .

Florida State University's Center for Advanced Power Systems working in conjunction with Keuka Energy.

Last winter in Lubbock Texas we characterized a new wind machine design using rim drive on a 25 foot diameter wheel (can see the wheel design here: http://www.keukaenergy.com ) and we got an average of 35.4KW out of it at 20MPH (11.176MPS) wind speed. During gusts measured to 43MPH (19.222MPS), we saw in excess of 38KW - at 660VAC.

For real. They are going back in a couple of months to characterize a 50' machine with twice the generator (two generators rather than a single one).

Wind power - she's a changin. :cool:


The power a wind turbine will extract is related to the area of the turbine and the wind speed, plus an efficiency factor since no turbine is 100% efficient.

There's a good table relating power (watts) to wind speed (mph) and turbine area (square feet) at http://www.ndsu.edu/ndsu/klemen/Perfect_Turbine.htm

A few data points ...

5 MPH wind, "good turbine" (for efficiency) will deliver 0.2 watts per square foot of swept area.

10 MPH wind, 1.75 watts per square foot

15 MPH wind, 5.9 watts per square foot

As a guess, a typical rooftop exhaust vent turbine will have an area of 1 or 2 square ft. Let's say 1.5 square ft.

Since the power produced is not linear with wind speed, multiplying these numbers by the average wind speed will not produce accurate results. Fortunately, the referenced web page has calculated monthly energy production using a Rayleigh distribution of wind speed.

If the average wind speed is 10 MPH, which may or may not be representative of your location, you will generate 2KWH a month of electricity with a "good" design turbine per square foot of turbine area. (There's a map of estimated wind speed for the US at http://www.windpoweringamerica.gov/pdfs/wind_maps/us_windmap.pdf. However, the wind speed data is for 50 meters (165 ft) above ground level, and typical house height wind speed will be much lower unless you live on top of a tall ridge.)

We've assumed 1.5 square ft for the projected area of a typical roof ventilation turbine, so that's 3 KWH per month for one turbine, hooked to a generator.

Here in northern Virginia, we pay a bit under 10 cents/KWH for power from the NOVEC co-op that serves our area.

So, you would generate 30 cents worth of electricity a month based on all these assumptions. Feel free to plug in more accurate numbers.

In my view, the only reason to make a turbine generator at this scale would be for amusement; it certainly is not a cost effective way of generating anything more than a trivial amount of electrical power. A small solar cell array would be more useful.

Jack
 

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Most residential sites would benefit more from buying a few extra solar panels than from a wind generator - and that's a paraphrase from a website that sells wind generators.

IIRC, even 30 foot towers are not tall enough in most areas to clear the obstructions that interfere with sustained winds (that close to the ground)

Here in the SE USA the only good wind sites are in the mountains & at the beach and localities there are increasingly banning _all_ turbines (mainly because they fear the aesthetic impact of huge commercial installations)
 

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A number of others have asked the same question about roof top turbine vents. The bottom line is no. They well never produce useable power.

The angle of the blades, mounting location, size, bearings and other factors all go against producing usable energy. They spin with ease, but with out any torque.

Even a prop from an airplane fail to capture energy from the wind.

Anyone/everyone who have flown wind turbines (both home made and commercial built) ALL report unacceptable noise in the home and less than desired performance when they are roof top mounted.

Taking on a wind power project is a major project.

I recommend that you (and everyone else) check out the forum at

http://www.fieldlines.com/board/
 
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