What he wants to do doesn't make a whole lot of sense.
Yeah - sometimes the goal is actually resulting in more energy inputs than realized (saved) in use.
However, one of the most interesting aspects of cycling is the ever changing energy potential of the bicycle/rider matrix as it climbs and descends hills and or navigates windy areas.
How wonderful would it be if a rider could choose to "store" the energy gained from climbing a hill and use it as needed to power or charge accessories. (charge during downhill)