Monongahela, Pennsylvania (CNN) It sits on the banks of the Monongahela River like a monstrous monument to extinction.

With no fire in its belly and no smoke in its stacks, the rusting power plant provides only one sign of its former inhabitants, scribbled on a white board in a padlocked guard booth.

"RIP Mitchell," the handwriting reads. "You gave us a good few years."

A whiteboard in the shuttered plant commemorates Mitchell, which closed six years ago.

The Mitchell Power Station, just south of Pittsburgh, actually turned Pennsylvania coal into power for a good 65 years before the discovery of cheaper, cleaner forms of energy.

As fracked natural gas and renewables like wind and solar undercut the price of coal, both Mitchell and the nearby Hatfield's Ferry power plants were deactivated on the same day in 2013.