I loved watching old sci-fi movies where a small hand weapon or small spaceship could have as much power as a thousand nuclear bombs and never run out of energy. In comic books, the super hero had unlimited energy and strength to change the very Universe itself. Robots can power energy weapons, fly and move heavy objects on only a basic electric charge. What do all these things have in common? They all violate one of the most basic tenents of physics: the conservation of energy.The First Law of Thermodynamics states that energy cannot magicly appear out of nowhere or disappear; it will always exist, albiet in a different form. Anytime something uses energy, it has to come from somewhere. The books must balance. This is also called the law of Conservation of Energy.
So if Cyclops from the X-Men shoots out a laser beam powerful enough to destroy tanks and Jean Gray and Professor Xavier can lift tons with the power of their mind, where is their energy coming from? It can’t be coming from their natural biological processes: the human body doesn’t have enough potential energy to power those kinds of applications. If they are “superhuman”, then where is this energy stored? The energy for superhero powers has to come from somewhere.
Mechanical devices are more problematic because they are by definition bound to the laws of physics. How much power does a robot use that it can fly at supersonic speeds, transform and fire powerful energy weapons? It can’t use 100% of its power effeciently because that would violate the Second Law of Thermodynamics. Exosuits seem to have huge power reserves and run for hours without recharging, but how are they storing and converting that energy without huge batteries or power plants?
When writing science fiction, you always have to ask: who’s paying the electric bills?
 I have read at one point that mutant powers in the X-Men universe come from some sort of extra dimension. So how does a biological entity tap into it and use it? Why can’t machines be built to directly run off it?
“With regards to your conservation of energy entry in the Hall of Infamy, I would just like to say that Cyclops (along with several other super heroes such as Super Man) gets his power from solar energy. Supposedly, these ‘solar-super-people’ are able to store vast quantities of solar energy for use in whomping on bad guys. I doubt, however, that they could absorb or store enough to do everything they do though.”
Note to the boys at Marvel: Keep trying, one of these days you might just get it right.