Yale Environment 360: Exporting U.S. coal to South Korean power plants could cut greenhouse gas emissions by 21 percent compared to burning it at less efficient U.S. plants, according to researchers at Duke University. The strategy could also generate more than $25 billion in economic activity in the U.S. and cut emissions of sulfur dioxide, nitrogen oxide, and particulate matter, the researchers say. For those benefits to occur, however, U.S. plants would need to replace the exported coal with natural gas, and South...