Seconding this - we made a set of rectangular wooden frames with a layer of clear plastic stretched over the front and back and a strip of foam attached to the outer edge. They pressure-fit into our old windows and do a solid job reducing the draft. Quilted curtains help too.
The downside is that the two layers of plastic make the windows hard to see through, but frankly that’s not a high priority where we are, especially when it’s cold.
For a long while Savonius wind turbines were popular with the DIY self-sufficiency crowd. Solar panels blew them away in terms of home power generation and lack of maintenance but they were easy to DIY and they work well in the kinds of locations where the big prop windmills don’t make sense, like bolted to roofs and to the sides of building.
They do sell premade wind turbines ranging from ones intended for yachts to full size ones but the permies forums have a lot of neat discussions on home small wind and small hydro.