I have come to the conclusion that electric aeration will be the most practical. I have several factors that I have to consider, but I can make electric work. Cost is a BIG factor. The source for my electric will be our horse stable. The pond is about 250' away. My wife doesn't want to listen to a compressor all the time while she's at the barn and I don't blame her. So I have to position it far enough away that it won't be too annoying. So I will place it about 50' from the stable, and run 5/8 full burial air line the rest of the way. to the pond. I ordered an Airmax PS-10 compressor that is supposed to put out ~55 db of noise, which is pretty low. So I only have to run a conduit and wire 50'. Heck, the air line is cheaper than the electric conduit alone, much less including the wiring.
Assembling and installing a windmill seems like a lot of work. Servicing the compressor would be difficult as well, and the initial cost would be higher. All that for an intermittent and unpredictable system. I like the controllable, reliable, and easily serviceable nature of the electric system.