When I first heard the phrase “clean coal”, I was amazed by the proximity of these two words. I’d never once thought of coal as clean. I’d never touched a piece of coal without needing to wash my hands. It was a memorable phrase, and after I’d heard it again and again – and seen it on an immense billboard in Pennsylvania, I got to wondering if there was such a thing. Clean coal is something we could all hope for, and want to believe in. The US has 25% of the world’s coal reserves, so it is abundant. Coal provides almost half of US electricity, and about half of the world’s new electricity demand for the past decade, so it is important. And…