I don't understand why power house regardless of what fuel they...

I don't understand why power house regardless of what fuel they use don't recycle the water.
e.g. air conditioners recycle gas to liquid to gas. We don't keep puting gas in the system.
also why they don't use salt water to produce steam to drive turbines,steam is condense to water and put in to dams. Desalinate it.
I am told the Navy does it with their ships.
Seems the way to go. Does anyone know if they do this, and where.

Cheers