The main problem with this and many such ideas is that G (the universal gravitational constant) is just so damn small. Making this system store any serious amou

The main problem with this and many such ideas is that G (the universal gravitational constant) is just so damn small. Making this system store any serious amount of energy in a small footprint is limited by the density of materials you can raise and the height available. In a large footprint you need a lot of infra (eg: loooong rail) which has maintenance cost, and still, very small per-liter and per-m^2 efficiency.