MidAmerican Energy Co. and the Sierra Club have reached a settlement in federal court after the Sierra Club said MidAmerican was in violation of the federal Clean Air Act at three of its coal plants. 

The Iowa utility company will phase out coal burning at seven coal-fired boilers, clean up another two coal-fired boilers and build a large solar installation at the Iowa State Fairgrounds. MidAmerican maintains that it has been and remains in compliance with the law, adding that it entered into settlement discussions to avoid costs to its customers and unnecessary delays.

The Sierra Club said that today's announcement brought the total amount of coal generation retired or announced to be retired to more than 50,000 megawatts, almost one-sixth of the nation's coal fleet, since 2010.