It's said that if a space elevator were made then it would be much more efficient to put objects in orbit. I've always wondered about the durability of a space elevator though. I don't mean the material strength but rather what affect using the elevator has on the elevator.
To put some massive object in orbit requires increasing its potential energy by a lot. Where is this energy coming from? Is the energy 100% from the fuel used to power whatever climbs the elevator? Is energy sapped from the Earth's rotation? Does climbing the elevator move the counterweight at all and does the position of the counterweight have to be adjusted after each climb?
I assume that a space elevator can be used over and over but I'd like to understand what the ultimate source of energy is and what allows for elevator re-use.