TVA outlines its plans, so far, for a new Paradise gas-fired facility

When the Tennessee Valley Authority said Nov. 14 that it will retire the coal-fired Units 1 and 2 at its Paradise plant in western Kentucky, and replace that capacity at the same site with a gas-fired project, it didn’t give any detail on the gas project.

But TVA recently released a final environmental assessment on the Paradise options that contains Alternative C, the gas-fired option. Eventually rejected was the alternative that would have seen the installation of pulse jet fabric filters for particulate control on Units 1 and 2, which have a total of 1,408 MW of capacity. The newer, 1,150-MW Paradise 3 coal unit would not be retired. The TVA Board of Directors gave President and CEO Bill Johnson the power to decide exactly when to shut the coal units, but that would only be when the new gas plant is operating at the site.

During a Nov. 18 conference call, Johnson said it would be a few months before TVA decides upon exactly what natural gas option to pursue.

Alternative C includes construction and operation of a new combustion turbine/combined cycle (CT/CC) plant with a summer capacity of up to about 1,025 MW when operated in combined cycle mode. This alternative also includes associated gas pipeline(s). The CT/CC plant would be located just north of the existing coal pile and to the west of the Green River on an approximately 50-acre site.

Alternative C would include:

  • Installation of three or four natural gas-fired CT generators each with a capacity of approximately 200 MW.
  • Construction of 161-kV transmission line(s) from the main switchyard to a new switchyard at the CT/CC plant.
  • Construction of natural gas pipeline(s) to connect the plant to interstate gas pipeline(s).
  • Installation of an auxiliary boiler to provide start-up steam for the surviving Paradise Unit 3.
  • Should fuel oil be selected for use as the back-up fuel supply, install fuel oil storage tanks and unloading station for tanker trucks.

Plant components specific to CC operation include:

  • Install three heat recovery steam generators (HRSG) and one steam turbine generator to utilize waste heat from three of the combustion turbines.
  • Install a water–cooled condenser and a mechanical-draft cooling tower.
  • Install auxiliary boilers to provide start-up steam for the CC plant.
  • Install primary water intake structure in the Green River; potential secondary water intake from existing BAP 2A for makeup water required for operation of CC-specific equipment.
  • Install pond for processing discharged wastewater flows from CC operation.
  • Install selective catalytic reduction (SCR) system for NOx control.

One of the four CTs would not get a combined cycle configuration

The major CT/CC plant components include three or four CT generators with inlet evaporative cooling, three HRSGs, one steam-turbine generator, one natural gas-fired auxiliary boiler, three natural gas-fired dew-point gas heaters, one multiple-cell mechanical draft cooling tower, one diesel engine–driven emergency firewater pump, two fuel-oil storage tanks, and a water-cooled condenser. Three of the CTs would be connected to the HRSGs and the other CC-specific plant components. The fourth CT would be configured to operate independently of the CC-specific components.

Reduction of NOx emissions from CTs would be achieved through dry low-NOx combustion and low-NOx burners. The CC plant would use an SCR system located within the HRSG for additional NOx reduction. Reduction of carbon monoxide would be achieved using a catalyst. The new exhaust stack(s) would be equipped with continuous emissions monitoring systems for carbon monoxide, NOx, and oxygen.

Preliminary estimates indicate as much as 200 million standard cubic feet per day of natural gas would be needed for future CC plant operation. This demand would require a lateral pipeline up to 24 inches in diameter at up to 1,200 pounds per square inch of pressure. Based in part on information provided by potential gas suppliers, two potential pipeline corridors are being evaluated, Corridors C1 and C2. Corridor C1 would include an approximately 20-mile lateral pipeline running west of the plant. Corridor C2 would include a 10- to 16-mile lateral pipeline running northeast of the plant.

TVA said it is considering a redundant fuel supply for the CT/CC plant. This would consist of a second gas pipeline connecting to an interstate gas pipeline or the ability to fuel the combustion turbines with fuel oil. The fuel oil option would require CTs configured for dual fuel, construction of onsite aboveground fuel oil storage tanks with a capacity of approximately 5 million gallons. Fuel oil would be trucked to the site.

TVA would also need to construct and operate two new 161-kV transmission lines and a 161-kV substation associated with the new CT/CC plant.

About Barry Cassell 20414 Articles
Barry Cassell is Chief Analyst for GenerationHub covering coal and emission controls issues, projects and policy. He has covered the coal and power generation industry for more than 24 years, beginning in November 2011 at GenerationHub and prior to that as editor of SNL Energy’s Coal Report. He was formerly with Coal Outlook for 15 years as the publication’s editor and contributing writer, and prior to that he was editor of Coal & Synfuels Technology and associate editor of The Energy Report. He has a bachelor’s degree from Central Michigan University.