This is actually pretty embarrassing for me but a question just popped in my head today and in my three years of studying Engineering Physics nobody gave me the answer: Why is it that heat effects are always considered as energy loss? Really. I understand that's not really convenient if energy dissipates from your device to the outside environment, but isn't it possible to compensate that effect by building a second system around your device wherein you do something useful with that heat? (I don't know, like for instance create energy by letting a thermal flow drive some sort of fan, a sort of wind energy) Or is the rub simply that this process always keeps occuring: so that in your second system there is also heat dissipation, in the system you build around that one too, etc. etc. But even then, doesn't that make it odd that in practically every device there is no such thing as a second system? Or would such a system simply be ridiculously inefficient? If so, why? Is it because this heat dissipation is not controlled in any way, and so you can't design your second system in such a way that it functions in harmony with your dissipation effects?