Three U.S. senators on Monday urged the Internal Revenue Service to crack down on a $1 billion-a-year subsidy for burning chemically treated refined coal after a new study showed some power plants using the fuel produced surging amounts of mercury and smog instead of cutting pollution.  Scrutiny from Rhode Island’s Sheldon Whitehouse, as well as fellow U.S. Senate Democrats Elizabeth Warren of Massachusetts and Sherrod Brown of Ohio, comes after a Reuters special report in December revealed that many power plants burning refined coal pumped out more smog, not less. Companies can qualify for the subsidy by showing pollution cuts in lab tests. Pending legislation in the Senate would extend the coal subsidy program another decade, costing taxpayers at least $10 billion at […]