Renewable Energy Questions/Discussion > Wind and Hydro

chain driven transmissions

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bvan1941:
Chris,
with what gains you have demonstrated with your type of transmission, it would seem the concept lends itself to scale itself down to make marginal generators (high rpm/v type generators) become much more productive. This would enable the marginal generators to enter their useful power band better than trying to go with higher tsr rotors. This would be especially important in "low wind" and seasonal wind areas. My thoughts are to minimize the requirements for high speed rotors and produce more average output  in between higher gusts of sporadic wind, normally required to produce power from marginal generators.

what's your take on this idea?
Bill

ChrisOlson:
There has to be gains in generator efficiency that outweigh losses in the drivetrain to make it worthwhile.  You're trading torque for speed and it really takes a generator designed for the high speed to make it work.  Trying to use "marginal" generators, such as automotive alternators which take a lot of speed but are still only about 55-60% efficient won't work all that well.

With my latest turbine design that uses a geared drive, I got 86% power efficiency from the generator at 2.8 kW output, using ferrite magnets.  Those are the kind of numbers you have to shoot for in your design to make it viable.
--
Chris

bvan1941:
Chris,
My concept was to use a potential generator like a 1500-3000 RPM, 3 phase motor, was what I was driving at. Some of these units are very capable of providing 2-4kw of power when operated in their proper speed range. That would definitely make these motors much more efficient and keep rotor speeds under 400-500 RPMs.  This would be I think, be better than having the rotor requiring wind speeds of over 20 knots for excellent outputs. Some of us are really in very marginal wind belts and only have decent wind for less than 2-3 moths out of the year. With your type transmission suitably sized I think this would be a measurable improvement.
Hope I've cleared up the thought of using any auto type alternator.
Bill

ChrisOlson:
Just to be clear, using a transmission is not the magic formula for getting more power out of marginal wind sites.  It can be if you use a very large rotor with a geared generator.  No matter what you do, getting power from wind still depends on two things - swept area and wind   :)
--
Chris

Wolvenar:
What are the drawbacks to using a larger blade with gear up in lower but usable wind speeds (over 10mph)

I am looking into this possibility for an alternator (zubbly style conversion) that has a slightly higher than I hoped for cut in. Id rather not rewire this beast if I don't have to there is a lot of copper in this thing. I'd be happy to get a higher consistent output and early furl than trying to go for the bigger winds

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