The Tennessee Valley Authority is taking comment until Sept. 9 on a draft environmental assessment that covers new emissions controls – or unit retirements – to meet the federal Mercury and Air Toxics Standards (MATS) at its coal-fired Paradise power plant.
The Paradise Fossil Plant (PAF) is located in Drakesboro, Ky. MATS, recently issued by the U.S. Environmental Protection Agency (USEPA), regulates emissions of hazardous air pollutants (HAPS) from existing coal- and oil-fired utility steam generating units of 25 MW or greater and affected sources must demonstrate compliance with MATS by April 16, 2015.
USEPA established a particulate matter (PM) limit of 0.030 lbs/mmBtu as a means of demonstrating compliance with the MATS for non-mercury HAPS metals. TVA’s proposed actions include installing new emission controls on PAF Units 1 and 2 to meet the PM standard or replacing this coal-fired generation with a combined cycle /combustion turbine plant. PAF Unit 3 meets MATS and requires no additional action.
The approximately 2,500 MW of capacity provided by PAF is important in maintaining an adequate and reliable power supply to the north-central portion of TVA‘s service area. For PM controls, TVA is considering installing pulse jet fabric filter (PJFF) systems on Units 1 and 2. As an alternative to installation of emission control equipment on PAF, TVA is considering replacing Units 1 and 2 with a combined cycle (CC) and/or combustion turbine (CT) plant (CC/CT plant).
Additional goals of TVA‘s proposed action include minimizing overall costs, maximizing the use of existing TVA facilities, minimizing construction of new transmission system components and upgrades of existing transmission system components, and maintaining a balanced portfolio of energy sources.
Paradise plant fires Illinois Basin coal
TVA began construction of PAF in 1959 and completed Units 1 and 2 in 1963. Construction of Unit 3 began in 1966 and completed in 1970. PAF is located in Muhlenberg County in western Kentucky. The plant is on the west bank of the Green River.
PAF Units 1 and 2 are coal-fired cyclone units with a rated capacity of 704 MW each. Unit 3, which is not in danger of being shut, provides a rated capacity of 1,150 MW. Combined, the three units have a generating nameplate capacity of 2,558 MW. PAF typically generates 14 billion kilowatt-hours of electricity a year.
The units typically burn coals from nearby counties in western Kentucky and southern Illinois. Coal is transported to the plant by truck, rail, and barge. For rail delivery, a 2.2-mile-long railroad spur managed by CSX Transportation provides access to the plant. U.S. Energy Information Administration data shows that coal suppliers earlier this year were KenAmerican Resources, Armstrong Coal and Alliance Coal.
PAF Units 1 and 2 are equipped with selective catalytic reduction (SCR) systems to remove NOx, and wet flue gas desulfurization (FGD) systems to remove SO2 and PM. Ammonia handling and storage is required to support SCR operations. The hydrated lime injection system was installed in the fall of 2011 to control SO3 emissions. PAF Unit 3 is equipped with an SCR to remove NOx, an electrostatic precipitator (ESP) to remove PM, and a recently installed FGD system to control SO2 and acid gases.
Notable is the fact that TVA is not the only utility recently to talk about retiring FGD-equipped coal capacity, going against the previous conventional wisdom that such plants were safe from the ongoing wave of coal retirements due to MATS and other new emissions regulations.
New gas facility would be about 1,000 MW in size
The gas-fired alternative includes construction and operation of a new CC/CT plant with a generating capacity of approximately 1,000 MW. It would replace generation from Paradise Units 1 and 2, which provide a rated capacity of 704 MW each. The CC/CT 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. This alternative would include the following depending on system needs:
- install three or four natural gas-fired CT generators;
- construct a 161-kV transmission line from the main switchyard to a new switchyard at the CC/CT plant;
- construct natural gas pipeline(s) to connect the plant to interstate gas pipeline(s);
- install auxiliary boiler to provide start-up steam for PAF Unit 3;
- install three heat recovery steam generators (HRSG) and one steam turbine generator to utilize waste heat from three of the CT generators (a water-cooled condenser and a mechanical-draft cooling tower would be required); and
- install auxiliary boilers to provide start-up steam for the new CC plant.
The above equipment may be constructed in phases, with three or four CTs completed and operating before CC-specific components are installed for CC operation. Long-term actions related to retirement to Paradise Units 1 and 2, such as the potential demolition of the units, are outside the scope of the draft EA and will be addressed by TVA in the future should the gas-fired alternative be implemented.