First I have to say that this is very cool indeed!
Practically speaking, however, I'm not sure that it would have any advantages over the flashlights that you crank for a while. Though perhaps those crank flashlights use a rechargeable battery that degrades over time, and this new flashlight would have a longer shelf-life? Though I should think a good capacitor instead of a battery would solve that potential problem with the crank flashlights.
will make quite a lot of light using a single NIMH AA that has been out of a charger for weeks (pushing ~ 1 volt...). It doesn't get you to 0 batteries, but it does a nice job of making light when you happen to realize you need it (without thinking about it in the interim).
I've never had one of those crank flashlights work after more than a few hours of use. I bought several for my kids, and they didn't even make it through a weekend camping trip. I also tried keeping one in my car, and found that the second or third time I tried to use it, it would light up dimly for a few seconds after several minutes of cranking. Some component, either the capacitor or the generator, has a very high failure rate.
Practically speaking, however, I'm not sure that it would have any advantages over the flashlights that you crank for a while. Though perhaps those crank flashlights use a rechargeable battery that degrades over time, and this new flashlight would have a longer shelf-life? Though I should think a good capacitor instead of a battery would solve that potential problem with the crank flashlights.