http://www.eink.com/press/releases/pr97.html
The displays are bistable, meaning they only use power when an image is changed. The displays are bistable, meaning they only use power when an image is changed.
http://66.102.9.104/search?q=cache:xFqux1XK02UJ:www.ifa-show.com/2005/philips_review/101_philips_e-reader.html+rollable+displays+battery&hl=en&ct=clnk&cd=5
The battery will keep up for 10 to 30 hours. Philips managed to reduce the power consumption for the display to almost zero, that is 0%
I was wondering how they are powered looks like a battery which by the looks of it could last a long time!
I know its a crap and stupidly basic way of saying it but its basically a lot of balls with colour on, once you used power to get them in position you need next to nothing to keep them their, its just the brightness of it really which again from other tech is getting better.
The thing that needs to come along for these to be super useful with no sizable device on them and controlling them (although a laptop with a fold out 20inch screen would be amazing (you can see it now, laptop, little stand like a projector stand and pull the screen out, lol)) is as you point out the battery, decent batteries that are small (take the 360, not there yet, lol)
Power does need a bit of a re-think tbh, but anyone once you got that and the control system small - very sci fi.
Id stab at saying 10 years for really useful digital paper and about 5 for some use.