A perfect example of the law of unintended consequences:
BILLINGS, Mont. (AP) -- U.S. coal exports reached their highest level in two decades last year as strong demand from Asia and Europe offered an outlet for a fuel that is falling from favor at home.
[. . .]
King Coal faces a tougher outlook in the U.S., where competition from cheap natural gas and costly new rules for power plants are eroding its historic dominance in electricity generation.
New EPA rules on coal are meant to improve or at least protect the environment. But the result is more coal sold overseas, where it will be burned by countries with far looser environmental regulations than we have, or none at all. So it's a double whammy: The environment gets hurt while the U.S. economy takes a hit, too. Sweet.