There's an easier way to think of it: consider how much space 500 houses take up. Now consider how much space one windmill takes up. The windmill isn't very big compared to the houses, is it?
Also, consider how much farmland it takes to feed the people in those 500 houses. Then consider that you can stick a windmill in the middle of a field and it only displaces crops in the area occupied by its tower's base (plus some room for maintenance and maneuvering), not the width of the blades.
If you take the example of a small town and plop a single windmill in Farmer Bob's cornfield, you can power the whole town. If you put a windmill in Farmer Joe's soybean field too, you can power that town and the next town over. If you put a few windmills near every small town you might (I haven't done the math) end up with enough leftover power for all the big cities.
The point is, 80k windmills sounds like a lot, but it really isn't.