Natural gas levels are also low I've read, and getting coal moved around will suffer from too many dead vaxers (supply chain failures) and a lack of diesel. Pretty fun when large swaths of the US go dark in the middle of winter for days at a time, I would imagine. In the South probably not so big of a deal, as long as it isn't below freezing, but in the North it will cause a big problem, with people dying from exposure and what not, inability to cook anything or have water to drink.