Every body knows, that according to Newton's law, isolated vacuum-flask won't spontaneously overheat. Solar-powered machinery would seem sci-fiction in the early times of industrial machinery, now it is standard. And we're not yet even talking about "ever-hot" tubes made from rocks...
What I'm trying to get information about, is that if we can utilize heat in air or sea water to power the machinery. I wonder what problems can occur in system like that and what should system like that look-like.
I was thinking of compressor, that heats up the air, and then heat engine running in closed loop with some gas that allows for big pressures at lower temperatures than steam. It could lead up to closed loop, where heat engine is powering the "extractor", it's heat source.
Is that possible? How would you construct such systems? What problems can creators of this run into if not a wall of vacuum-flask they supposedly live in?