Yeah, hard to imagine a cheap little windmill with metal blades (like I'm sure I've seen) costs more than its lifetime energy output would cost. Guessing more to do with the large ones, wasn't sure on that. He did seem to think it applied to even the small battery charging one you mentioned... no idea. In that scenario it's not about cost anyway, or if it is, the right cost to compare to is building power lines to the remote location (you can't say it's the same fixed cost as in a modern home when there's no availability at all)