>>21945724Because Powder River Basin Coal, in Wyoming, is low in sulfur, and in the early 90s an amendment to the Clean Air Act of 1970 went into effect that greatly damaged the Illinois coal industry, which supplied much higher energy but also higher sulfur coals.
Wyoming Powder River Basin coal is subbituminous in rank, having around 8,000 BTUs per pound, while Illinois Basin coal is bituminous in rank and ranges from 11,000 to 15,000 BTUs per pound.
Basically, coal-burning power utilities didn't want to pay for sulfur scrubbers and so they switched, in the 90s, to Powder River Basin coal, but other countries are more than willing to buy up high energy Illinois Basin coals.
Also, Wyoming coals are in terrible decline, a decline far exceeding Appalachian or recent Illinois Basin coal production declines, because export markets are the new big thing for American coal and low energy Wyoming coal is not worth the cost to export.
