> Idea: Could elevators be retrofitted with something like this? I think it would not work so well because they have counterweights to make the up-down operati

> Idea: Could elevators be retrofitted with something like this? I think it would not work so well because they have counterweights to make the up-down operation much easier. If you remove the counterweight, it would store energy, but be prohibitively slow when going up and probably frighteningly fast going down. Regarding the uhaul, this is not too far off from other people mentioning driving a train uphill and letting it fall downhill to generate electricity. Interesting ideas.