I've been wondering something about automail. Specifically, what powers it? Arakawa states that it's powered by electricity generated from human muscles. I suspect that this is a lot of, as Star Trek might put it, technobaloney. While I do know that the human body -- mostly the nervous system -- generates an electrical field, I suspect that 1) the power generated is too low to power up to three kinesthetically capable automail limbs, 2) the electrical field produced is the wrong kind of current to power machines, although I suppose this could be solved with the aid of sufficiently clever adaptors, and 3) even if there was enough electricity produced by the body, the automail would draw it off and drain the field to such an extreme degree that that field would no longer be able to serve whatever purpose it's originally supposed to be fulfilling.
But I don't know. So here are the two questions I'm asking.
1) How much electricity does the average human body produce, and what manner of electricity is it? -Question for a bio major.
2) About how much electricity would it take to run a motor sufficiently powerful to accomplish the sort of tasks we see automail routinely accomplish? I mean, we see Ed lift a chimera (which I'd estimate to weigh oh, 500 pounds at the least) with that arm alone, and crush metal in his bare hand. That's a question for a mechanical engineer if you've got one.
 Someone in the comments estimates that Ed displays at least 2,200 watts of force using his arm. This link, kindly provided by Google, estimates that "a sleeping person can produce 81 watts, a soldier standing at ease can produce 121 watts."
I'm seeing a bit of an energy gap here...
What I suspect is that there's no way the two numbers would match up, and there's obviously some other explanation for the automail's power source. The obvious one, of course, would be that it runs on the same principle as the other phenomenon that pulls energy out of nowhere; alchemy. There's no reason to think that only certain people in Amestris are capable of practicing alchemy, although of course not everyone does; it's also clear that some people can muster fundamentally more alchemical charge than others. So does Edward's mechanical strength (both the flesh and the automail) correspond to his spiritual strength/strength of will/whatever it is that determines alchemical capability?
Edit: To clarify, I am not suggesting that automail runs on alchemy in the sense that it uses arrays, requires conscious activation on the part of the alchemist. What I am suggesting is EPISODE 51 SPOILERS as Hohenheim suggested, alchemists power their transmutations by opening a 'gate' inside them to tap into the alchemical power source. Could the automail be drawing on the same power source? When you consider the amount of energy needed to power a matter rearrangement as opposed to something as simple as mechanical movement, one would think that even people with very little alchemical talent could do it.