Powering mechanical butterflies (Score 2, Interesting)

Okay, so my question is how one could possibly power a mechanical butterfly. Living butterflies subsist on nectar; it's high energy, but they still need a massive daily intake. So, it seems like powering a butterfly would require a super-light-weight battery with long life and high output. Photovoltaic wings might work, but then it couldn't fly at night. Any thoughts on other sources of power? Superconducting monofilament extension cords?

And incidentally, the article says that insect wings get 10 times as much lift as airfoils. Presumably, that's for airfoils moving at the speed of insects. Has anyone found a way to test this with a butterfly moving the speed of a jet plane? I'm curious if the proportion holds true at all speeds, or if the ratio collapses as speed increases.