Building mounted wind turbines

[fabricator]

I am hoping to get input on the effectiveness and efficiency of building mounted turbines, I will be at a symposium on wednesday where one of the panel participants will be a representative whos company builds the Swift Turbine http://www.swiftwindturbine.com/  intended to be installed on houses in rural and urban settings, a basic Swift Turbine system starts at fifteen thousand dollars, I would like to make sure people know the facts about building mounted turbines.
I know the industry rule of thumb developed over the last one hundred years or so is five hundred feet away from and thirty feet above the nearest turbulance causing object, this machine seems to simply ignore that most basic rule, any input would be appreciated.

[Timeless Turbines]

Fabbricator,
Some people can't put up the tower they want and are ok
With just being as green and as they can be. I think you should
Look into a 80' 4 post tower like mine for your self.? Have you.

[ChrisOlson]

I know the industry rule of thumb developed over the last one hundred years or so is five hundred feet away from and thirty feet above the nearest turbulance causing object, this machine seems to simply ignore that most basic rule, any input would be appreciated.

The industry rule of thumb is one thing, but a wind turbine will make power anywhere it can capture the power of moving wind, including on rooftops.  Ed Lenz lives in Lansing I think and would probably be able to give you an idea on effectiveness and efficiency.  Ed probably has more experience with it than anybody here.  This photo of Ed's rooftop turbine was in Popular Mechanics a few years back:
http://www.palebludot.com/2008/01/08/ed-lenzs-wind-turbine-powered-home/

--
Chris

[joestue]

a basic Swift Turbine system starts at fifteen thousand dollars

LOL
"Sustainable, harm neutral design - allowing SWIFT to become carbon and energy positive within four years"

not at 15K USD it isn't.

i hope thats a typo and you meant 15 hundred.

[electrondady1]

well, 15,000. is a lot of money for what you are going to get out of that swept area.
there is good wind around here on the shores of lake Huron ,but i live in an urban environment.
hawt require the sort of height and space  around them you describe.
vertical axis machines are the solution for me and that's what i build.
you might want to inform people about the amount of energy in the wind .
and just how much of it as a percentage  can be captured.

people want to do the right thing.
but with out studying this stuff like we all have done  it's easy to trick them.



 

[Flux]

Yes a turbine will make power anywhere there is wind. There are occasions where the things are justified even under conditions that normally would be ruled out.

Sometimes on some of these "useless" sites things can work quite well for winds from one particular direction. If you want serious power reliably at sensible cost then these sites normally are not viable. The power available on a clean site can be estimated well enough from average wind speed but this no longer applies when there is turbulence. The de-rating factor may be modest or huge depending on the site.

If you must take the chance then it is best to stick to small turbines, they suffer less than larger ones. Don't expect much useable power except for the odd wind direction and you may not be disappointed.

In addition to the poor yield on poor sites you need to consider the effects on the building if it is mounted on one. Small machines may be ok but this depends on the type of building and how it is built. You have noise and vibration to deal with at the very minimum.

Unless you live somewhere where mounting on a building is unavoidable and you can get by with very little power then just rule it out. It really is a last resort option, it may or may not achieve what you want. Don't let some idiot sell you such a thing as a going concern and promise you reliable results, I would never buy anything but if you can build something cheaply and are aware of the traps then it may be better than nothing.

Flux

[ghurd]

Hugh's site.  Scroll about 2/3rds down to "ROOFTOP MADNESS CONTINUES..."
http://www.scoraigwind.com/
G-

[SparWeb]

If you're doing a slideshow for the talk, here are some diagrams that could help:

http://www.solacity.com/SiteSelection.htm

Rob Beckers (website owner and copyright holder) allowed me to use that info when I was doing a similar talk last year.  He might be happy to provide the graphics to you.

The next thing to take on are just a couple simple numbers:  A turbine seeing 8 mph average wind speed will produce about 1/2 the total energy in a year compared to the same one in 10 mph.  The penaly for turbulence around buildings can be 50% or worse.

Once facts like these are put in front of people, they can make their own choice.  To green-wash their house for bragging purposes, or to become bona-fide producers of electrical energy for their own practical use or sale to the grid.  It's their money.

[fabricator]

Just so we are all clear here, I wouldn't buy one of these things if I won the lottery, I just want to be able to explain the realities of this type of thing to people who know less than nothing about wind power.

[TomW]

Just a "fer instance"

Some years ago I installed a GarboGen on a pole attached to my garage. Just a rigid mount of standoffs mounted to the main structural components [8X8 Creosoted Bridge beam halves] and it worked.

Thing is, whenever it got to charge RPM and above there was this pleasant hum that would eventually become annoying after the initial "cool, power is coming in" euphoria passed.

Sleeping in such a structure would be an issue I think.

And it was only only like 6 feet plus diameter and attached at 2 spots into an upright heavy timber and not bolted entirely on the roof.

Just from here and the actual real world of structure mounting for me.

No doubt you could isolate to some degree but most buildings simply are NOT engineered for a turbine type load and eventually I expect the roof to fail and likely in a spectacular fashion.


Tom

[ChrisOlson]

I think before somebody gets up on the pulpit and starts preaching that roof mounts are no good, they have to remember there's all sorts of people out there.  If somebody wants to buy a turbine and mount it on their roof, I don't really care, nor am I going to stand there and tel them it won't work.  That's like somebody who wants to buy a Hummer instead of a Ford Explorer, or whatever.  They might not care about practical because they want it and got the money to buy it.

If you think you're going to "save the reputation" of wind power by preaching that roof mounts don't work - forget that too.  I'd guess that something like 99% of the general population don't even care in the first place.
--
Chris

[Rover]

I have a small test turbine ~ 5 ft mounted on 1 1/2" pipe, slid into a 2"  bolted to the side of my shed through a seriously reinforced wall (2x4 " s  side by side) . Number of blades help the vibration at low rpm, higher # lower vibration, I'm running 6. The pipe in pipe is damped somewhat by covering the 1 1/2 " portion that slides into the 2" with a bicycle inner tube.

Still the vibration is annoying, as is the sound, I would not want to live in the shed, cabin or house with it attached.

Still, as evidenced by my marina, there are a lot of sailboats out there with mills on em, I guess vibration is dampened somewhat by the water. But the noise can be deafening. Of course these are smaller turbines as well, but it does show there is an application for mounting a turbine on a structure, albeit a floating one.

[ghurd]

My 25.5" mini ECM windmill audibly vibrates the whole car in a good wind (20~26MPH).
The blades are almost totally silent...  The car is loud.
When it gets up around peak output, its creepy to be in the car with the noise and vibration.
I do not know if the tires let it get resonating, or dampen it, I just know it is loud.
G-

[bj]

   I've commented on this subject before, and will again, just because I have lived with a roofmount, for almost
three years.
   Did it work?  Yes, to the best of it's capability.
   Was it noisy?  Yes, terrible.  I'm quite deaf, (both ears) and the noise is the main reason I took it down.
   The plus side was that my friends stopped showing up with projects they wanted to do in my shop.
   Not trying to preach from the pulpit, but anyone new should know about noise issues before they try it.
   That way at least they know the possible problems before making decisions.
    Just that 2cents again

[Rover]

I guess I'm curious as to how the Swift people, taking them at their word for roof mounting, and there are design aspects (in my ignorant opinion) that may "reduce" the vibration and noise effects.

1. 5 blades , may help vibration
2. Ring collar on the blades may reduce tip noise

However, these have nothing to do with efficiency issues

From the brochure  "Flexible mounting options - rooftop, pole mount
to side of building, or stand alone pole mount"

OK from which of these did they generate numbers? or from a controlled test environment.  We are still talking about a 7' mill dealing with turbulence, effect of roof , proximity , height  etc

[DamonHD]

Will they give categorical enforceable guarantees (backed by say an insurance bond) to homeowners using their equipment that their roofs, eg masonry, will not be rattled to pieces ("suffer unexpected early failure modes") and satisfy (say) UL to that effect?  Wind and static loading of solar PV/thermal is rather easier to understand!

Rgds

Damon

[fabricator]

I don't know about a lot of this stuff but I'll find out Wednesday night, I do know where there are a few of these things in "operation" Meijer, our regional supermarket chain around here has them mounted on several of their stores, the store in Grand Haven MI has about eight of them on the store, this location is less than a mile from Lake Michigan.
The store has a flat roof and they are mounted right on the west edge above the main entrances, on the east side of the lake here we have prevailing westerlies, at any given time even in high winds there will only be four or five out of eight spinning and none will be pointing the same direction.

[DanB]

It just depends what you want to do I think.
I expect there are a few (very few) situations where a roof mount might make some sense.  Generally not though - it's been pretty well shown that a roof top is not a good wind resource and I won't get into noise/vibration or structural issues.

People keep doing it - lets just see some data (any data... please!!!) of a situation where it makes sense from a cost/kWh perspective.  I doubt anybody can show that.  But if you love wind energy and you want something on your roof... and don't mind the noise, I should say go for it.  I fully intend one day to put one on my shop... for fun. 

Here is one thing I notice though.  Everybody wants cheap electricity... everyone (well... lots of people) think it'd be really nice if a wind turbine on their roof could:

- be silent
- not kill birds
- etc etc
- reduce the electric bill and make a for a 'good investment'

Anytime that *lots* of people want something, somebody will be quick to offer it for sale - this applies to wind energy, magical cancer cures, eternal salvation etc etc......

[artv]

Hi all . Roof top turbines don't work;..  because of the turbuance??....Design the roof to channel the wind to the turbine,align it with the sun and use its' energy too as in solar assit........just a thought..........artv

[DanB]

Just for those who have not got round to it yet... Ed's machine that Chris pointed out is probably among the best.
It produces about 50kWh/month, probably at best, and 10% of his electricity needs.  That seems like a good one, and very realistic.  I expect the swift folks or most other 'roof top' folks are making much less realistic claims.

[JW]

There's one thing to consider that can be referenced thru an Anemometer, its average kwh. When determining long engine/dyno runs, kwh is often referenced. The same should be the case here.

If your referencing wind speed trends using a local anemometer, then the kwh output should be relative to that...


JW

[B529]

this machine seems to simply ignore that most basic rule, any input would be appreciated.

The machine is not ignoring this basic rule, the scumbag company and their BS marketing is ignoring the rule.

I can't figure out how to post an article written by Mick Sagrillo, "Wind Doesn't Work". I believe the PDF file is too large? It gives real world numbers from roof mounted turbines, VAWTS and wind data of a roof mounted anemometer. The output on all the case studies is disgustingly low, no suprise there. The calculated payback on the roof mounted turbines is 890 years.

Could someone help with posting the PDF file, it's a good read.

We have something that works on roofs, solar. That would be the message I would passionately bring to that meeting.





 

[JW]

Could someone help with posting the PDF file, it's a good read.

Send me a PM, and I will give you my email that can handle large files, from there I can see how we could link to it.

JW

[ChrisOlson]

Just for those who have not got round to it yet... Ed's machine that Chris pointed out is probably among the best.
It produces about 50kWh/month, probably at best, and 10% of his electricity needs.  That seems like a good one, and very realistic.  I expect the swift folks or most other 'roof top' folks are making much less realistic claims.

I know they are using ideal condition numbers, as much of the rest of the wind industry does, including Bergey, Jacobs, you name it.  I don't remember the exact specs of Ed's "Lenz2" turbine, but I think it's like a 400 watt machine at pretty good wind speed up around 28-30 mph.  At 50 kW per month, that's about 70 watts average output in a 24 hour day, which I think is pretty realistic.  And Ed's VAWT is probably less affected by turbulence than a horizontal machine would be.

The difference is, Ed didn't spend $15,000.  He built it for $300.  That makes a big difference for the average person as to whether or not it will pay off.
--
Chris

[fabricator]

You got that right.

[Rover]

Noise/vibration are subjective ... so most ad departments can get away with, t is is quieter etc ... individual tolerance levels vary , unless it does structural damage

Now, show me a manufacturer's ad department that shows the ROI on the capital outlay for the installation environment (on grid) , .. take the current one at 15K$ targeting urban (grid tied, want to save money.. yada) ... tell me the ROI

[Rover]

...as a side note, I think I can market a building mounted widmill (not turbine) , that will spin up in virtually any wind (of course this is not power producing) so that urbanites can tell their friends they are being green. figure 100$

Kinda like the fake securty cameras , looks real , does nada

[DanB]

Wind is just a really tricky resource to harness, as most of us know.  Even with the most 'common machines', on tall towers, that are seemingly well figured out, it's a challenge to produce cost effective electricity.  Add the roof bit... and it becomes damned near impossible and I will stand by that until I see some figure from somebody who's actually made it work out.  (real figures)  There are a few real figures out there that suggest it's simply a bad idea and none that I know of that suggests otherwise.  That is... unless 'fun' enters into the picture and then I should say go for it.

[Rover]

G, agreed

and  this isn't target at people "who know their stuff" ... those that do have conversations like this , those that don't .. well ?

[ChrisOlson]

There are a few real figures out there that suggest it's simply a bad idea and none that I know of that suggests otherwise.  That is... unless 'fun' enters into the picture and then I should say go for it.

For once I have to agree with DanB.   

I know a fellow who has a single 35 watt solar panel with a grid tie inverter.  Now, that can't be very cost effective but it's "fun" and he likes it.  Same applies to rooftop turbines.  Some people will put them up just because they want one and they think it's cool.
--
Chris

[artv]

Chris  You  Nailed it,..money don't talk ,it Screams...............artv

[wdyasq]

IF, I were an inspector reviewing such a system, I would want to see a structural analysis of the building WITH TURBINE ATTACHED.

I think the idea would be as appealing as sheep droppings in a salad if the same requirements as a free-standing tower were applied.

Ron

[bob g]

lets see how this works out,,,, 15grand for a rooftop wind machine?

rates average what?  10cent/kw/hr

so the thing has to harvest what? 150 thouand kwatt/hrs just to pay for the unit?

hmmmm, in an average wind area?  with maybe at best an average daily wind speed of 7 mph up on the roof?

my bet is it couldn't make a kw/hr in a day on average, in an average location, atop an average home.

so we need 150 thousand days to get to break even?

lets see, 150k /365 = 400 plus years!

and somehow this is supposed to make one feel green?

green with anger maybe after they find out they have been duped!

and this makes sense how?

bob g

a fool and his money are soon parted, but some things are just criminal