Just looked at a video of the atlas rope ascender (google it) and thought it was pretty cool. However, I feel as though using a more "capacitive" approach and taking advantage of the fact that ascensions would not occur frequently could allow for the use of a system that slowly recharges over time, either using capacitors or stored mechanical energy (springs). Unless I am missing something, I imagine capacitors would require large DC motors still. Going to a small, light system, are there any torsion springs that can store large amounts of continuous energy, possibly put some in series or parallel. Essentially, like a huge watch spring able to output ~500-1500 watts for a few seconds. Some target specs: 350 lbs at 5 ft/s ~ 300 watts, but this seems questionably low to me. If this is right, at 50% efficiency, I imagine 600 watts would be an absolute minimum. Shooting for 50 feet, 10 seconds * 300 watts = 3 kJ of energy. Is this even ballpark feasible?