Coal is in no shortage. The US has at least enough to last for 200 years at current demands. That amount is only for what reserves we know of. We can safely rely on coal for at least the next hundred years before we can expect problems. Nearly half those reserves are lower quality, lower energy density sub bituminous and lignite coals. Another obvious point is that global demand is not static. Even with modest demand growth, consumption doubles in just a few decades at most. But if we're trying to electrify our car fleet, then the demand will grow even faster, leading rapidly to the possibility that coal supplies could peak within a quarter century. It's already happened with the highest quality coal. Production of that peaked in 1917 in the U.S.