| It would sure be nice to just pull the generator head off of an old portable gasoline generator and make it into a small wind turbine, wouldn't it? There are thousands of dead portable gensets available for free because the gasoline engines have worn out.
Unfortunately, there is really no way to convert the alternators from these free generators into something that would work for wind power generation. The units are usually designed to spin at a steady 3600 RPM. They will produce their designed 120 VAC power at 60Hz ONLY when spun very close to that RPM. More expensive units might use 1800 RPM. This causes multiple problems for building a viable wind turbine alternator out of them:
- Small wind turbines by nature vary in RPM with the wind speed.
- The alternators from portable generators use electromagnetic coils inside to produce the magnetic field needed, instead of permanent magnets like in most wind turbines. If you don't get these electromagnets spinning up near 3600 RPM, there's not enough magnetism, and therefore no power output.
- Could you just gear the alternator up enough with belts and pulleys, cogs and chains, gears, etc. so that the electromagnets spin fast enough? And then use some sort of regulator to control the magnetic field? Not really. You'd run into some big problems:
- You'd lose a bunch of power from the friction in the gearing. It would ruin your low wind performance (low winds are by far the most common)--all this loss comes out of the system before it would even start making power for you.
- In high winds, the gearing would be spinning the wind turbine blades FAR too fast. How would you slow them down if needed? If a mechanical brake failed, your wind generator would be toast.
- 3600 RPM is much faster than is easy to deal with for wind power. A car alternator would actually be a much better choice for wind....but it's still only barely feasible since car alternators still need 1000 RPM or more to start making power. See the FAQ about exactly that:
- http://www.fieldlines.com/story/2003/11/4/12921/5571
- This whole snakepit full of problems is why we build our own, specially-designed low-rpm permanent magnet alternators for wind generators! There are simply NO commercial or surplus substitutes for an efficient alternaotr that matches your set of wind turbine blades.
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