Not beeing a scuba diver I know little if nothing about this matter, but… Could you manufacture a re-breathing system with hand-driven electric generator for emergency situations.
The latestin re-breather technology. It’s kinda cool.
I don’t know about your hand driven electric generator being hand driven underwater…Hmmm, not sure of the benefit after several hours scrubbing O2 out of your CO2.
I may be incorrect here, but a CCR can be entirely mechanical. All you need power for is the diving computer which calculates what mix you should be using at what depth. You can either adjust this manually, or breathe pure oxygen. Your lungs and the counter-lung is all the force needed to push your gas through the CO2-filter.
Mongo WANT!!