Regenerative braking elevators exist: https://www.asme.org/engineering-topics/articles/elevators/what-makes-an-elevator-green https://www.asme.org/engineering-t

Regenerative braking elevators exist: https://www.asme.org/engineering-topics/articles/elevators/what-makes-an-elevator-green https://www.asme.org/engineering-topics/articles/elevators/w... has a good summary. Having lived in a 17-story building with Thyssen-Krupp "green elevators", they're terrible! An elevator would break down and require days of maintenance every couple months, greatly increasing queueing times.