Panasonic's prototype fuel cell can run a notebook for up to 20 hours. If the notebook operates at 13 watts or less, which is about average, the fuel cell powers the notebook. If draws more power than that, a battery helps run it. Panasonic says it has no plans to commercialize this fuel cell device just yet--it wants to shrink its case to fit flush with the notebook case. A version of the fuel cell might hit the market in 2007 or so.