The coal stockpile at the Laramie River Power Station in Wheatland, Wyoming, is so big that you can't really see beyond it. It is similar to standing on the beach and looking out over the ocean, except this is one is made of coal – 35 acres of it. That's enough to produce electricity for about one month.
As a source of power, coal is predictable, easy to store, and well understood. Renewables and natural gas share few of these characteristics and some see that as a huge problem.
As the Environmental Protection Agency puts the finishing touches its proposal to cut carbon dioxide emissions – known as the Clean Power Plan – warnings that the transition away from coal will impact grid reliability are getting louder.