By buying powder river basin coal, China is attempting to clean up it's act at least a little. It could continue to burn the crap is has and maintain it's current level of pollution, and if this process goes on too long they could just decide to do that. No matter what, they will burn coal, they are not going to shut down just because of the greenies here---they just don't work that way. (In fact, they have been known to do the opposite of what the western world wants--just for spite.) Keep in mind too, that Japan may start burning coal again as the people there have expressed they would rather have that than Nukes. These countries just don't shut down stuff because we say so, only our country does that---and we enrich these countries by doing so.