[baruchel]

When you compute some nice and elegant result, dissipated heat is an undesired side effect. But let's face it: we are speaking about proof of work. Proof of work means that a computed has run during some "required" time. In other words, you have to prove that enough heat has been dissipated. Waste of energy actually is "by design" here.

[fainpul]

I'm not sure if you're trolling. Of course that's nonsense. The work is entirely the (artificially complex) computations necessary to get to the result. If someone were to invent a 100% efficient computer, based on superconductors, which produces no heat at all, the proof of work (the final hash value) would still be equally valid. As I said, heat is an undesired, unavoidable side-effect. You don't show anybody the heat you produced, to convince them that you did the work, you show them the hash value, otherwise you could just burn some wood.