Columbus-based American Electric Power will pay $8.5 million and stop burning coal at three power plants by 2015. The changes are part of a revision to a 2007 settlement between AEP, the U.S. Environmental Protection Agency and several environmental groups. It was the largest settlement of its kind in U.S. history, and the EPA said the new regulations would save the nation $32 billion in health care costs. AEP petitioned to have the settlement reopened to so it could make less-expensive pollution controls to an Indiana plant. In exchange, AEP will stop burning coal at a plant in southeast Ohio along the Muskingum River, and two plants in Kentucky and Indiana. AEP also agreed to produce at least 200 megawatts of power using wind or solar technology by 2015.