There is a logistical problem. These are reeeeeeally big cats. Did you ever see the TV show, Roseanne? These cats are the feline equivalent of John Goodman and Roseanne Barr, and about as old. They make Garfield seem lithesome. I would need to build some sort of restraint/harness thing to hold them in place, something fairly sturdy.
Then again, what if we just strapped one of them (humanely, with cushions) into a stationary frame, and put the other one on something that would rotate or spin? Since we're talking about a power loss situation, it would have to be on a hand crank. I'm not sure exactly what sort of wiring would be needed to collect the power, but I leave that to Morandir and his tech skills. Then there's the need to keep the cats cool as the friction would generate a certain amount of heat. Anyway, once we finalize a schematic, we could post it in the appropriate segment of the forum, as a service to other members. How's that sound?