Combined-cycle technology enables NYPA's 500-mw power plant to generate 50 percent more electricity from its fuel than it would with a conventional single-cycle power system. Under this dual-phase system, two combustion turbine-generators operate in conjunction with two heat-recovery steam generators and a steam turbine-generator.
In the first cycle, fuel is burned and the resulting combustion gases power two turbine-generators to produce electricity. Hot exhaust normally lost during this process is captured and routed through the two heat-recovery steam generators. These units boil water to create steam, which spins an additional turbine-generator and produces more electricity. Finally, the steam is discharged into a condenser, which returns the steam to its liquid state for recycling.
The Power Authority began building its first combined-cycle power plant on Long Island in 1992. The Richard M. Flynn Power Plant, in Holtsville, Suffolk County, produced its first commercial power on May 1, 1994. At the time it was built, the Flynn plant was the cleanest fossil-fueled plant in New York State in terms of nitrogen oxide emissions, and it remains one of the cleanest. Because of improved technology and stricter air quality standards, NYPA’s 500-mw facility is even cleaner.