Darrieus on Roof

[zorro84]

Hi

I am at the feasibility process of a project I am doing about wind turbines.

I am not a specialist, as you will realize, I am just a mechanical engineering student interested in the topic, and hence I working on the installation of a couple of Darrieus wind turbines on the roof of my Engineering Building.

As far as I know Darrieus (or VAWT) are more suitable for such projects, as in fact power is produced regardless of wind direction.

The size is still to be calculated, but something like 5-6 m would be suitable, as the building is quite a big one.

The problem is. How to install those turbines?

I must minimize the weight per spot, meaning that I have to split the weight of the turbine on various locations of the roof.. What is the best solution for this?

Note that the roof is not flat; you can see the pic and the map in the links below

http://tinypic.com/ofpukg.jpg

http://tinypic.com/ofprmv.jpg

Thanks a lot for you replies and help!

(or at least for the time you spent reading my post )

[vawtman]

Hi Zorro is there a way you could post the pics?A vawt that size would tear apart any building.You would need to scale her down alot.

[thefinis]

I have to agree with vawtman that trying to place a turbine that big on the roof isn't feasible unless it was designed for it. On a public building liability concerns will need to be meet too.

Hmmm if you are a mechanical eng student then isn't this your area or expertise? Figuring loads, calculating structure needed to handle loads etc. I think you are going to need the help of an architectural prof with the building's blue prints just to see what can be done. I am pretty sure that the gabled ends are going to have been built to handle standard roof loads only.

Good luck

Finis

[windstuffnow]

  If the weight and loading is spread out over a larger area then the roof will hold the machine without any problems ( depending on the weight and size of the machine of course ).   A single pole mount with guy wires will concentrate the weight and load at a single (small area) point.  If it's built on a 4 or more post with larger surface plates the load will be spread out more. As well, you can take advantage of the stronger structural points of the building.  If you have a large area to work with then the task is easy (depending on how well the original structure is built ).  

  If the weight and load is spread out enough and it's built on the peak of the roof you can actually design it so it doesn't need to be bolted down at any point as long as the ends are properly weighted to maintain more force than it would take to move the turbine in a given wind.  Here is an example of a small one mounted on the roof with out bolting it down... http://www.otherpower.com/images/scimages/15/L2_on_roof3.JPG .  This is simply an example and you'll have to do your homework to make sure what your planning is even feasable.  This is a test machine and I simply wanted to get in a temporary setting without disturbing the roof in any way.   It's been in winds of 60+ mph without moving the structure, I figured it would take 70-75 mph winds to get it to move.  Hopefully I'll never get to see the limits of my engineering.  

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[vawtman]

Ed hes stating that 5-6 meters would be suitable.5-6ft might be attainable if its somehow freefloating from the structure and not attached in any way.I think even then there would be some vibration issues dont you think?Maybe not short term.

[zorro84]

Thanks for the replies!

Unfortunaly I can't post the pics on here, don't think we can do that. The link is working anyway!

I saw the pic of the turbine on the roof. I was thinking about something bigger than that, as the building is quite a big one, about 30m X 10m x 30m

I tried to find out the maximum allowable weight on the building, however an external structure engineer is needed, and the university isn't ready to pay of that yet.

Anyhow, what kind of turbines do u think I could install on such building? 10k at 5m blades height and diameter is too big? Smaller electricity values would be insignificant compared to the consumption of the building (around 350kWh)

[zorro84]

I forgot to state that the wind velocity is not too high. About 4-12m/s, with average wind speed of 5.5

[windstuffnow]

  Your right vawtman, a unit that large would most likely be better served with its own out building providing a nice "power station" for controlling it and distribution.  It could be done as a floater as long as the building was sound.   It may be less expensive to provide its own building as opposed to redesigning a structure to accept it.  With a darrius it's best to keep it in an area where there isn't alot of foot traffic.   It's not a matter of "if" but "when" it will fail.   A place where it's least likely to hurt someone when she blows... I'm not a big fan of the Darrieus, can you tell?  

.

[vawtman]

Zorro its not the weight of the turbine that matters.Its good ole Mother Nature that controls how you go.Start small and have a good time.Ill see if I can put in a good word for you.Sneak a couple small ones up there and youll see what were saying.Eds design that you saw earlier seems great.

[amiklic1]

You can read something from the expert in wind generators area Paul Gipe at http://www.thesolarplan.com/articles/roof-top-wind-power.html

In another article he has mentioned (even there was the picture) the school in Canada that had wind turbine on the roof, but it was removed after large cracks appeared in the building structure. There are lot of vibrations, especially from the turbine that large. I wouldn't reccomend even think of that. Just my 2$.

[zorro84]

hey angjelo!

So basically what you are saying is that I should consider smaller wind turbines, in the range of 1-4 m ? or even 4 is too big?

The fact is that the building is really big, then a higher load might be installed on the roof.

I understand however the concept of vibrations, that's why I decided to select a smaller one.

Do you know if there is any place I could find informations about installing a turbine on a roof? where to place guyed cables and such information?