President Donald Trump loves coal. He has given dozens of speeches saying, “My administration is putting an end to the war on coal. We’re going to have clean coal, really clean coal.”But what actually is clean coal? Depending who you ask, it could be a historical reference, a fantasy or an evolving technology. In Wyoming, a state that produces the most coal in the nation, clean coal is looked at as a possible economic savior. Without it, the industry faces a possible long, slow decline.