In a settlement with the U.S. Environmental Protection Agency, the Tennessee Valley Authority has agreed to shut some coal-fired generating units and install new or upgraded pollution-control equipment on others to cut air-pollution emissions at 11 of its powerplants. The pollution-control improvements will cost an estimated $3 billion to $5 billion. Under the settlement, announced on April 14, TVA will shut 18 of its generating units, which equal about 16% of its coal-fired electric power capacity. EPA says the measures will cut TVA nitrogen-oxide emissions by 69% and sulfur-dioxide emissions by 67%, compared with 2008 levels. The settlement addresses alleged violations of the Clean Air Act at TVA powerplants in Alabama, Kentucky and Tennessee.