For decades, Southern Co. has been one of the nation's largest electric utilities and one of the leading consumers of coal. Southern believes coal-fired capacity should remain part of its generation mix. Its Mississippi Power subsidiary—one of four utilities Southern owns—is building what may be one of the last coal-based units in the U.S.: a 582-MW integrated gasification combined-cycle (IGCC) unit, sited in Kemper County, that is scheduled to come on line by the end of this year.