Let's talk... energy sources?

Panem's technological achievements include invisible forcefields, city-wide booby traps, disturbingly extensive camera networks, and the ability to change a landscape with the push of a button, among other things. So with all of this, I've been wondering...

Why the heck do they still need COAL?

It's just so odd to me that they'd rely solely on a nonrenewable, polluting energy source that's not super-easy to obtain, especially given how small District 12's working population is. The Capitol's way of life depends so much on electricity that it alone seems like it'd require more energy than the coal would provide. Are there energy producers elsewhere we don't know about? (I assume 13 has a reactor somewhere, but that wouldn't help places elsewhere.) Does coal only power the districts, while the Capitol itself has oil, solar panels, etc.? Is a fuel shortage partly why the districts don't have anywhere near the facilities that the Capitol does? Do they not believe in global warming even though the ice caps already melted? What's the deal?