Why is impossible for the elevator to be 100% efficient? What other less useful, types of energy are being produced as the elevator climbs?

Energy is wasted mainly as heat.  The heat is produced by:
- friction between moving parts (e.g. inside motor and by between elevator and guide rails);
- (for electric-motor driven elevators) heating of wires by the current.

There is also some energy lost as the elevator moves through the air, giving the air some kinetic energy (i.e. air resisitance).  This causes the air to get slightly heated.

It is impossible to avoid these as:
- friction is always present;
- unless you use superconductors, energy is always turned to heat when current flows through wire;
- unless you operate in a perfect vacuum, there is always air resistance.

Sorry, my answer is "Anonymous" as your post is Anonymous. There is no need for an Anonymous question in this category, Most 'Anonymous' posts are trolls, maybe yours is not, but the high likelihood is there. If you post as yourself, I would be glad to help you with any problem you have.
I spend a lot of time on each problem, I just want to make sure it's for a worthwhile cause.