Energy Options > Wind Power

Why not lots of cheap mills?

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mangyhyena:
I noticed it can be fairly cheap to build a vertical windmill.  Saw one that was made with 2 halves of a 50 gallon barrel.  The problem with them seems to be small amount of power production, especially if used at ground level.  The major cost of a mill seems to be the generator/alternator unit, not the blades.  Also, putting a windmill high up on a tower looks like a major part of the cost.

So, I'm wondering if several of these cheap mills could be linked, at ground level, to just one generator/alternator.  Would several of these cheap mills working together equal one better built, more expensive windmill?  Why or why not, please?

Not challenging anything with this post.  Just trying to understand why I don't see multiple mills linked and working with one generator.  Thanks.

TexDaddy:
I imagine it would be the cost and complexity of setting up the mechanics to have several windmills turn the armature of the generator.

On the electricity producing windmills I have seen, the blades are mounted directly on the armature of the generator. You would have to introduce drive rods and a crankshaft to hook several together to run the same generator. This in itself would reduce the power available to turn the generator. In addition, the head of the windmill would still have to be able turn into the wind, while keeping the upper crank and the drive shaft connected. Of course, that part can be done similar to the windmills used to pump water into cattle tanks.

tipafo:
It shouldn't be that complicated.

http://en.wikipedia.org/wiki/Savonius_wind_turbine

One rotor turns one small alternator/generator, and the current is "ganged" together with an array of other small turbines.  The combined current flows through a charge controller/inverter and then to the main AC panel.  Similar to how individual solar panels are ganged up and the currents combined.

Something like this, but free-standing, made of metal, turning an automobile alternator/generator, should produce a useable current in a decent wind.

http://www.youtube.com/user/embeddedprogrammer#p/u/18/KnE_aVFxJQE

Of course, as with solar panels, it would require many such turbines to create a reliable source of electricity.  (Or mechanical power, as these "windmills" can also pump water, etc.)

I've not tried it, yet, though I've wanted to for years.

TexDaddy:
That is a cool design, but each 'stack' would require its own generator. It doesn't address how to turn only one generator with multiple windmills. It does make it where wind direction is not a consideration. It would be interesting to find out how many could be stacked, but pretty soon you would have a tower/costly support structure, another thing the OP wants to avoid.


--- Quote from: mangyhyena on July 07, 2011, 06:00:40 PM ---...The major cost of a mill seems to be the generator/alternator unit, not the blades.  Also, putting a windmill high up on a tower looks like a major part of the cost...

So, I'm wondering if several of these cheap mills could be linked, at ground level, to just one generator/alternator...
--- End quote ---

In the big commercial operations, the generators in each tower are "ganged" together and the currents combined for transmission.

Perfesser:
I saw a guy who had many 3 bladed heads on a single shaft, maybe spaced 4 ft apart. Even in a light wind they did pretty well.
Found something like it if you want to investigate further.
http://www.speakerfactory.net/wind_old.htm
Scroll way down to the early models with 14" blades. He's also in an ideal location with 30 mph winds. Temper that with your probably closer to 5 - 10 mph.

I think this has a lot of advantages over a turbine with long blades. The gyroscopic forces escalate quickly when you increase blade length requiring a strong mount and tower, special blades. This design would have much less of those stresses yet still have good performance in low winds. If the blades are kept under 3 or 4 feet or so you could use the ones cut from 5" PVC pipe.
DIY- smaller scale, say 3 heads on a 10 ft. shaft, belt pulley in the center and run a generator off a belt.

Yet another project I wish I had time to pursue.

 

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