Switch the balls with water, and the channels with turbines, and you have discovered a hydroelectric reservoir, which is quite feasible, given that quite a few

Switch the balls with water, and the channels with turbines, and you have discovered a hydroelectric reservoir, which is quite feasible, given that quite a few are already built. > Once all balls are on the bottom, generated electricity is used to rotate the whole thing and start process anew. If here, you mean part of the electricity generated by the flow, then it can't work because pumping it back up is subject to friction (in fact, generation from when it flows down is also subject to friction) and to mechanical/electrical conversion losses. On a 100% efficient system with no losses, you would get perpetual motion, but subtracting any energy from the system would make it slow or stop.