you are correct in pressurizing the water does add cost in both running the pumps and in the heavier and more costly equipment. Even with this cost, the savings in fuel for a big plant still pays.
I think this is the reason that small plants typically are not supercritical. They don’t burn enough coal to pay for the extra cost.!
That is the smaller ones that are less efficient.
What are the economics for the use of Natural Gas....?
Can a plant using the high pressure on water and coal be switched to natural gas....
Assuming a BTU doesn't care where it comes form....loosely speaking.?