Every year there's a mad scramble for power plugs during the lunch break...
How about combining the device charging stations with a cloakroom? Check in your bag and plug in your laptop, then scoot off to a session unencumbered. Security would be an issue I guess.
Alternatively some powerboards in the theatres would help keep people running. I've seen cords with single plugs spaced 1m apart, a few of those along the rows would probably work.