Interesting historical note on the energy requirements. When Stan Lee was developing the Iron Man character, transistor radios were coming into fashion. I remember him giving an interview where he admitted he didn't know what transistors were, but knew they let you make stuff smaller. To his mind: transistors = power boost, and that's why Tony could get away with the power-requirements he needed. Lots and lots of transistors, which (in the old comics) he was always recharging.