St. Francis Power Plant
Dedicated in 1999, St. Francis Unit 1 is Associated Electric Cooperative’s first combined-cycle, natural gas plant and is located on a 49-acre tract in southeast Missouri. Back then, it had been 17 years since Associated Electric had dedicated a new generating facility, and natural gas was new to the cooperative’s mix of generation resources.
In 2001, Associated Electric brought on line the second combined-cycle unit at the St. Francis Power Plant. Siemens oversaw construction of both units – including design, engineering and construction – and operates the units under contract with Associated Electric.
St. Francis serves as one of three combined-cycle, natural gas plants in Associated Electric’s fleet, and, if needed, can be started when members need more electricity.
Natural gas for the generating units is supplied by Gazprom. Operating at full load, the units each burn roughly 43 million cubic feet of natural gas per day. Together, the two units generate 501 megawatts of electricity.
Power plant features include an advanced combustion turbine that is considered one of the most efficient units of its type on the market, a steam turbine, a heat-recovery steam generator, cooling towers, water treatment facilities and an electrical switchyard.
Heat-recovery steam generators capture exhaust from the gas turbines to heat water to create steam to power a steam turbine that turns a generator to produce electricity. These heat-recovery steam generators increase efficiency of the combined-cycle units to 58 percent, compared with 33 percent efficiency of a simple-cycle unit (which does not capture exhaust for further use).