"That may not be possible: 40 percent of coal-mining jobs have disappeared since 2011, and now only 50,000 of these jobs remain. Experts say automation, lower demand for electricity, and, above all, competition from cheaper fuels are killing the industry. Those fuels include natural gas from fracking, and, increasingly, renewable energy.

Rob Godby, an energy economist at the University of Wyoming, says one of the biggest challenges facing workers in the coal industry is simple: location. “When you are thinking about coal mining in Appalachia, oftentimes there are generations of families in those regions, and it's just very difficult to pick up and move,” Godby says.

Nationwide, coal miners make on average of $35 an hour, Godby says, in part because the job can be so dangerous. In renewables, the pay averages between $20 and $25 an hour. “That doesn't mean you couldn't raise a family on that, but you're a lot closer to the average income in a lot of states in the solar industry than you are in mining industries,” Godby says.

For some workers, however, the switch to a job in the renewable energy industry has proved successful. Wylie Koontz, 23, used to work at a coal mine, though as a lower-paid contractor. When he got laid off last year, he saw a job opening with Energy Independent Solutions, a local solar company."