Alliant Energy Corp. and Empire District Electric Co. in March completed environmental upgrades to their 730-megawatt Ottumwa power plant in Iowa and 189-megawatt Asbury power plant in Missouri, respectively, that should allow the plants to meet the MATS rule, the companies said. Alliant spent $491 million and Empire spent about $130 million on the projects.

In Michigan, DTE Energy Corp. has spent about $1 billion on environmental improvements at its massive, 3,000-megawatt Monroe coal plant to comply with MATS and other EPA regulations, and is proposing to spend about $240 million on its St. Clair, River Rouge, Belle River and Trenton Channel coal plants to keep them running at least into the 2020s.

Indianapolis Power & Light Co., meanwhile, plans improvements at its largest power plant, the 1,700-megawatt Petersburg coal-burning generating station in Pike County, Indiana.

Wisconsin Energy Corp., until recently, planned to sell its 431-megawatt Presque Isle coal plant at Marquette in the state’s sparsely populated and transmission and generation-constrained Upper Peninsula to Upper Peninsula Power Co. (UPPCO), an Integrys Energy Group subsidiary. UPPCO had agreed to pay the token fee of $1 for the plant. Wisconsin Energy is in the process of acquiring Chicago-based Integrys for $9.1 billion.

But in March, Wisconsin Energy changed its mind and agreed to continue operating Presque Isle as a coal plant through 2020, a decision that means the utility also must install additional pollution controls so the plant complies with MATS. The projected cost of the project has not been determined.

By early June, an approximately $35 million project to install baghouses and activated carbon injection technology at the James River and John Twitty coal plants owned and operated by the city of Springfield, Missouri, is scheduled for completion.

In Kentucky, the Sierra Club is battling with the state’s two largest electric utilities, Louisville Gas & Electric Co. (LG&E) and Kentucky Utilities Co. (KU), over their plans to continue operating Units 1 and 2 at their 739-megawatt E.W. Brown coal plant on Lake Herrington near Harrodsburg.

But some coal plants are being retired across the region, mainly for environmental reasons.

Duke Energy Kentucky plans to shutter 163-megawatt Unit 6 at its Miami Fort plant near Cincinnati by June while LG&E and KU are preparing to close three coal units totaling 563 megawatts at their Cane Run plant near Louisville in May.

American Electric Power, one of the largest electric utilities in the country, plans to shut down six coal plants in Ohio, Indiana, Virginia and West Virginia by May, and several others next year. In all, AEP the coal retirements could represent about 6,000 megawatts.