Caledonia Combined-Cycle Plant

TVA leases the Caledonia Combined-Cycle Plant, located near Columbus, Mississippi.   

Efficient power production to help meet TVA’s intermediate power needs.

The Caledonia combined-cycle combustion turbines run on natural gas. The summer generating capacity of the plant is approximately 813 megawatts (MW). The plant consists of the following major components:

• Three 180 MW GE combustion turbines
• Three Alborg Heat Recovery Steam Generators (HRSG)
• Three 110 MW GE steam turbines.

The units at Caledonia can reach full power in two to four and a half hours, depending on the status of the units.

The units are capable of cycling on and off daily and are used 12-16 hours per day to meet “intermediate” generation needs, or power requirements extending over longer periods of time than peak needs but briefer than continuous 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 output from the same amount of fuel that would be burned in a simple cycle combustion turbine. Fuel is burned in the combustion turbine to produce electricity. The hot exhaust gas heat is captured in a heat recovery steam generator (HRSG) in order to produce steam. This steam is then used to drive a steam turbine to produce an additional 50 percent output. Additional steam can be produced by the duct burners for peaking needs.

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

Duct firing

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

Emissions

The combustion turbines produce very low NOx and CO emissions. The HRSG then utilizes an SCR (selective catalytic reduction) system to reduce the NOx to a very low level (approximately 30 percent of a simple cycle combustion turbine’s NOx emission using similar technology).

The plant's make-up water requirements are provided by waste water from the City of Columbus via a 16-mile pipeline.

The Caledonia Plant, which occupies 120 acres in Steens, Mississippi, 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.