To put some emphasis on something **si_blakely **mentioned, but only in passing …
If you simply had a drum at the top and a cable down to the elevator car with no counterweight, then the motor would have to expend a bunch of actual electrical energy to move the car to the top, converting some of that into frictional losses and the rest into gravitational potential energy.
A naive 1880s elevator would use a friction brake to control the descent, converting 100% of that gravitational potential energy into heat.
A smart 21st century elevator would use regenerative braking & electrical storage to capture most of the gravitational potential as reusable eletrical energy. You’d still have frictional losses, but since the system would weight 1/2 as much,they ought to be proportionally less as well.
As of today, the low-tech solution of a counterweight is cheaper / better. But at least in theory, we could produce a counterweight-less system which was lighter & as energy efficient over a round trip bottom-top-bottom.
Ball bearings and greasy cables have very low frictional losses. And pig iron counterweights by themselves are low mainenance and low cost.
Meanwhile energy conversion, either electrical-to/from-mechanical or electrical-to/from-storage device, is lower efficiency, ranging from 70-90%.
Which is why elevators today have counterweights. But 30 years from now ???
Other thought …
overall, there is nothing magic about
For any problem, there are smart & naive ways to solve it. A wheelbarrow vs. a wheelbarrow-like bin minus the wheel is an example of a smart vs. naive solution. And yes, there can be massive gains in efficiency using smart but still low tech solutions.
ETA: Joe’s more concise message wasn’t there when I opened this thread. Sorry for the partly redundant redundancy.