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Forum Index : Windmills : windmill in low wind speed areas
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| s4055451 Newbie  Joined: 19/09/2007 Location: Posts: 1 |
Does anyone know if there is any way of making windmills work in areas where wind speeds don't often exceed 30km/hr and average around 12km/hr? Is there some way of gearing a windmill so that you can have bigger fins running a smaller motor? Thanks for your help. |
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| KiwiJohn Guru  Joined: 01/12/2005 Location: New ZealandPosts: 691 |
To get the same power (i.e. watts) from lighter winds you need a bigger diameter. A bigger diameter, generally speaking, means lower RPM. There are a few ways around this, you could use gearing and I think there are pictures of geared mills using a cogged belt on this site. You could use a larger diameter generator which will tend to have a lower operating speed than a smaller diameter one, of course the F&P favoured at this site is in that category. Another thing you could do is just use a bigger generator operating at way less than its capacity or maybe a dual F&P. Plenty of things to think about. 
If you are willing to go away from the horizontal axis configuration I am sure there are vertical axis systems that could be designed for low wind speeds. There are a few people posting here who know at vertical axis machines and maybe we will hear from them. |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5116 |
There isnt a lot of power in low winds. But this doesn't mean you still cant harness what power there is. You either need to lower your expectations, or go BIG. My windmill can make over 20 amps in strong winds, but this time of year there is little wind here, and the windmill never got up to speed. So instead of hoping for 10 or even 5 amps, I changed the mill to make some use of low winds. I swapped the stator for a lower RPM version, adjusted the blades from 2 degrees at the tips to 30 degrees, and the result is a steady 0.5 amps almost all day long. Better than nothing, and at least the windmill is making power. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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vasi Guru Joined: 23/03/2007 Location: RomaniaPosts: 1697 |
Glenn, what is 30 degrees at the tips? Hobbit name: Togo Toadfoot of Frogmorton Elvish name: Mablung Miriel Beyound Arduino Lang |
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vawtman Senior Member  Joined: 14/09/2006 Location: United StatesPosts: 146 |
Hi S4 Heres my thoughts Others have pointed out the lack of power in low winds and gearing and slight cogging will take most of that. I had a 5hp converted motor on my largish vawt geared 1;3 at a windspeed it normally spun at 100rpms it wouldnt start.So now im working on a large inefficient alternator. The other thing is a turbine with many blades would be the way to go.Just make sure its built strong enough or has a lockdown device during storms. Good luck and welcome to the wonderfull world of wind. |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5116 |
For Vasi The stator I swapped over is rewired to have a lower cut in RPM. About 80RPM it reaches 12V. The 30 degrees at the tips, well my blade angle can be adjusted, so I turned them to give about 30 degrees, very easy to start and lots of torque, but wont spin very fast. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| vasi Guru Joined: 23/03/2007 Location: RomaniaPosts: 1697 |
Thank you Glenn, I "gather" every tips&tricks about running windmills on low speed winds (if this phrase is correct). Vasi Hobbit name: Togo Toadfoot of Frogmorton Elvish name: Mablung Miriel Beyound Arduino Lang |
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