I can't tell you why, because I don't know, but all the privately owned windmill generators that sprang up around here in the late 70s and early 80s are either idle or have been torn down. I've heard that they have an enormous initial cost, they can't be cheap to fix, and most of the time there's just not enough wind to do much with them. For all I know, maybe that's the whole explanation for their demise.
I didn't intend to say anything about solar energy here, but I just thought of something. I knew a guy who had a solar-heating system that actually worked really well. For starters, he had a very large insulated room in the basement that was packed full of rocks. His solar-heating capacity was far in excess of what he needed to heat the house, and the excess heat would be pumped into that room full of rocks. At night, and during cloudy weather, something we have a lot of in the winter, air would be circulated through those rocks to transfer the stored heat into the rest of the house. I think he spent upwards of 100,000 smackers on his solar heating system, and it still wasn't enough for total self-sufficiency, but it was a mighty impressive system! Also, though his house was pretty enormous, most of the whole south side was a two-story indoor porch enclosed by glass. On a sunny winter day, it would be more than 80 degrees on the upper floor of that porch, and by opening doors in the right combinations, that would go a long way toward keeping the whole house warm.
This kind of stuff can be found in all sorts of info articles, but it also illustrates how great the expense can be to really "do it right".