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Try looking into Savonius turbine designs and perhaps picture that on a horizontal axis. The light bulb wasn't invented until thousands of failed ideas and designs went by. I am going to try to build horizontally mounted savonius type turbines using sections of abs pipe cut in half as the "blades" or buckets however you want to look at it (look up savonius windmills and you'll get it). My thought is to make a series of several 4 ft (ish - I'm going to tweak till I get it right) long ~1ft diameter turbines driving a separate small car alternator each. I will then wire them up in parallel. That's the concept at least - I'm just now prototyping a small version. The advantages I see are cost, easy maintenance (nearly ground level), cheap (could possibly crank them out at less than $100 a pop), low profile, less noisy (I'm hoping) etc. As far as efficiency goes - they will certainly be way less efficient - however there will be many of them and the overall wind being harnessed will be much more than what I could handle by making a standard rotary 3 or more bladed windmill. Not to mention my neighbors wouldn't like it much.

Offered by Ken.

I am familiar with "savonius windmills" and think that is a good choice. I do think rather than mount it horizontal that vertical mount would be better. This would allow the wind to blow from any direction and make it work. If the generator is at the top then a large plastic or metal container could be put over it to protect it from the weather. If the generator is at the bottom then rain water can get into the main shaft ball bearings. In high winds the centrifugal force of rotation will tend to tear it apart unless a method of decreasing the surface area of wind exposure is provided. One way to protect against high winds would be to hinge the unit from the generator or highest end. As the wind blows harder the bottom part exposed to wind would cause the whole unit to hinge away from the wind, causing less cross sectional wind area to hit the savonius blades.

The next thing to look at is slow speed. Permanent magnet DC motors are more efficient at generating electricity than car alternators. Car alternators produce maximum power about 2000 RPM and at 500 RPM (typical car idle speed) much less power. As an example: Used Permanent Magnet DC motors that came out of 2400 ft Reel to Reel tape drives of the mainframe era are plentiful in surplus electronic yards and sell for about $5-10. I think the technical challenge will be to adjust the rotor diameter and your blade construction technique such that you get the maximum RPM you can. This is without it tearing apart from centrifugal force. All most all DC motors and car alternators are designed to operate at well above the typical 100 to 300 RPM that one can get out of a good well balanced windmill. This brings us to another possibility: By use of pulleys and belts or gears the speed of the rotor can be matched to the speed needed to properly drive the generator. This can get complex. It would be nice to not have to use these. I hope you can do it without this complexity.

Offered by Mike.