Chicago, the nation’s largest city to have two operating coal plants within its midst, long has had an uneasy relationship with the 532-megawatt Crawford and 326-megawatt Fisk stations. For years, neighborhood groups have complained about pollution from the plants, and environmentalists had stepped up their efforts to close the facilities.

Midwest Gen, a merchant power generator owned by California-based Edison International, agreed to retire Fisk and Crawford by the end of 2012 and 2014, respectively. In return, Emanuel promised to drop the Chicago Clean Power ordinance pending before the city council. If passed, the ordinance would have made Chicago the first city in the U.S. to regulate carbon dioxide emissions.

In return, Midwest won a commitment from environmentalists that they will not oppose the company’s plans to seek a one-year extension on a 2013 deadline to retrofit one of two units at its 691-megawatt Waukegan coal plant. Waukegan’s other unit faces a December 31, 2014, deadline to comply with the state’s regulation on sulfur-dioxide emissions. Midwest Gen will ask the Illinois Air Pollution Control Board to extend the deadline for both units until the end of 2014.

Doug McFarlan, a Midwest Gen spokesman, said the Chicago-based company hopes the Crawford/Fisk agreement “will help us stabilize the rest of our fleet…put it on better footing for long-term viability and investment. We don’t consider what we’ve done in Chicago to reflect our long-term view of coal.”

Once Crawford and Fisk close, Midwest Gen will be left with four coal plants in northern Illinois totaling slightly more than 4,000 megawatts of generating capacity. Midwest acquired all six coal plants in late 1999 from Commonwealth Edison for more than $4 billion.