Foreman John Dillon, a coal miner of 39 years, walks past piles of coal at the Sewell "R" coal mine Tuesday, Oct. 6, 2015, in Yukon, W.Va. In the U.S., where natural gas has become a cheaper alternative to coal to generate electricity, miners are facing an especially difficult market: Four major U.S. coal companies have filed for bankruptcy protection in the last 18 months. (AP Photo/David Goldman)