Southaven Combined-Cycle Plant

TVA owns the Southaven Combined-Cycle Combustion Turbine Plant, located in DeSoto County, Miss.

Efficient power production helps meet intermediate needs

The Southaven combined-cycle combustion turbines run on natural gas. The generating capacity of the plant is approximately 810 megawatts (MW) during summer operations.

The units at Southaven can reach full power in about one hour, depending on the status of the units.

The units are capable of cycling on and off daily and are used for 12 to 16 hours per day to meet intermediate generation needs, or power requirements that extend over longer periods of time than peak needs but are less continuous than base-load demand. The site is interconnected to both TVA’s and neighboring transmission systems.

How it works

Combined-cycle technology enables a combustion turbine facility to generate 50 percent more power than the same amount of fuel burned in a simple-cycle combustion turbine. Fuel is burned in the combustion turbine to produce electricity. The hot exhaust-gas heat is then captured in a heat recover steam generator (HRSG) to produce steam. This steam is used to drive a turbine to produce an extra 50 percent output.

The Southaven Plant has three combustion turbines. Each has one HRSG, which produces steam for one steam turbine.

Duct firing

Additional steam can also be produced by duct firing with natural gas in the HRSG. This provides additional power output for the steam turbine. The Southaven plant is capable of an extra 75 MW output due to duct firing.

Emissions

The combustion turbines produce very low NOx and CO emissions. The heat recover steam generator utilizes an SCR (selective catalytic reduction system) to reduce the NOx to a very low level (approximately one-third of a modern simple cycle combustion turbine’s NOx emission using similar technology).

The Southaven Plant, which occupies 118 acres in DeSoto County, Miss., is expected to help TVA meet the rapidly growing peak demands for power and reduce the need to purchase higher-priced power from external sources during periods of high demand.