Sounds like you’re on the right track there. As far as energy goes, you’re right, when things are dissipated, or all the same, you can’t extract anything. You need a differential, like a hot place and a cold one, a high voltage and a low one, a fast object and a slow/stopped one, a high object and a low one. The higher the differential the more you’re going to be able to extract. If it’s too small you might not be able to get any useful work out at all.