I can't make the powerplant at the start of the game, and I have it next to the yellow tiles.
I figured out why. The game starts you off with just enough money to buy a powerplant but each different square has a different additional price on top of the build price. I'm assuming it for piping because building the plant on water is free, but you would need to by the land for the waterer area and I can't do that, and all the land leading up to it to put in powerlines.