On of the reasons the capital of a power station is so high is that .1% gain in efficiency is worth a lot of money over its life time. If the fuel becomes cheap then you don’t need to worry about that .1%.
I know people here like to think that steam thermal cycles etc are primitive. They are not. They are highly optimized and rather efficient these days. And lets not forget the FF *needs* direct conversion efficiencies just to break even.
