Daylight would certainly be an option for enlarging. Fiber optics are being considered as a simple way to bring daylight into dark parts of buildings in order to reduce energy usage and cost. So why couldn't fiber optics be used to bring daylight to an enlarger as well?
As for running an enlarger during a power outage, you could always get a deep cycle battery and a power inverter. Even higher wattage inverters (ie 400+W) are pretty cheap these days.