To begin, thanks and a tip o' the hat to Dennis Brennan for the idea and inspiration.
I still have some tweaking on this to do, but it's about 95% complete. The main structure is an Atlas engine house with Ameritown cornices on either end. The smokestack is from an old Heljan brewery kit. I used strip styrene to for the foundation and trim. The roof is a piece of foamcore that is (theoretically) removeable. I had originally intended to illuminate the building, but there are too many light leaks, although I may add some exterior lights. I will need to alter a spur leading to the power house to accommodate a coal ramp.