JOHANNESBURG--June 14, 2012--Written by Richard Finlayson, Senior International Editor for Industrial Info Resources (Sugar Land)--The supercritical power plant in the final stages of construction for Prairie State Generating Company (PSGC) in Marissa, Illinois, is the largest coal-fired plant to be built in the U.S. since 1982. The first 800-megawatt (MW) unit of the 1,600-MW power plant has been commissioned, and Unit 2 is expected to begin commercial operations later this year.