I'm not going to give the Sierra Club all the credit (blame?) for the decline in coal use for power generation. They may have nudged the system a bi t, but by 2017 coal was already anything but a growing industry. That's a Good Thing IMO. The fact that it continues to decline in the face of policies that should encourage it to grow, without a lot of Sierra Club lawsuits succeeding, kind of says there's more to it than environmental lawyers. And we know what that is: very affordable natural gas, and increasingly affordable renewables. What we need now, to complete the conversion, is affordable storage. Any major infrastructure conversion needs help from subsidies and outside pressure to get going, but once it gets going it develops momentum; we're approaching that point with the decline in coal use.