would not your question be better directed to engineers who specialise in coal fired power stations?
it would be a most unusual, one could say an exceptional business or technology that cannot have improvements
I've rarely seen a technology that's fully developed
most technologies are superceded by newer techologies before they reach full development
an excellent and interesting example would be stone tool technology - cutting stone tools were replaced by metal tools well before they reached full development
how do we know this?
We know this because in the last years stone blades have made a huge technological comeback -- the highest quality surgical scalpels are now stone tools
so, the old biface axe was nowhere near the pinnacle of stone tool techological development
IMO at a guess, coal could be improved a lot, how? ask enginneers
