Oh, OK. I think that an energy recuperation system and simply a "vertical railway" is simpler and more robust overall. No ropes needed just electric wiring, and

Oh, OK. I think that an energy recuperation system and simply a "vertical railway" is simpler and more robust overall. No ropes needed just electric wiring, and elevators moving down are the counter weights. But this is basically what is demonstrated. What I thought parent meant was using counterweights in the more traditional sense. And yes, moving down also returns the energy, after all gravitational field is conservative. The real use of the counterweight is that the power needed to lift is less (you only need to work to lift the cargo), which means cost savings in motors, wiring, electricity, etc. Those saving by a mechanical counterweight system cannot be had with this setup without insane complexity. With today's solid state power electronics it is simpler and more reliable to use an electronic solution.