The Alabama Department of Environmental Management is taking comment until Feb. 7 on air permit changes that would allow Alabama Power to burn natural gas instead of coal at four of the five coal units at its Gaston power plant in Wilsonville, Alabama.
“Alabama Power Company has applied for Air Permits that would authorize the facility to retrofit four coal-fired electric generating units to add natural gas burning capability as a primary fuel,” said a department public notice. “The Air Permits would also authorize the construction and operation of a new natural gas-fired auxiliary boiler and a new natural gas-fired heater.”
The project would be expected to significantly reduce emissions of NOx, SO2 and particulate matter (PM, PM10 and PM2.5) from the facility. Alabama Power has indicated that there may be an increase in emissions of carbon monoxide (CO), volatile organic compounds (VOC), and greenhouse gases (GHG) above the prevention of significant deterioration (PSD) significance thresholds as a result of the proposed project. The department has concluded, though, that these increases in CO, VOC and GHG would not be expected to cause or contribute to a violation of the applicable National Ambient Air Quality Standards (NAAQS).
Alabama Power has proposed to retrofit Gaston Units 1–4 to add natural gas as the primary fuel. Natural gas would then be the startup and primary fuel for these units. Propane would be utilized as standby igniter/flame stabilization fuel only. After retrofitting Units 1–4, the nominal heat input for each unit would be 2,759 MMBtu/hr, while the full load gross generating capacity would remain at 270 MW per unit. The units would continue to use the existing stack configuration.
Alabama Power has also proposed to install a new natural gas-fired auxiliary boiler to assist with the startup of Unit 5 when crossover steam from Units 1–4 is not available. Propane would be utilized only as a standby fuel for the auxiliary boiler. The new auxiliary boiler would have a nominal heat input rating of 431 MMBtu/hr at full load.
Since natural gas is not currently utilized at the facility, Alabama Power has also proposed to install a new gas conditioning station with a natural gas-fired pipeline heater. This station would be used to raise the temperature of the natural gas delivered to the facility as necessary to meet the proper combustion specifications prior to being fired in Units 1–4 and the auxiliary boiler. The heater associated with the gas conditioning station would have a nominal heat input rating of 14.7 MMBtu/hr.
This project is needed to comply with the U.S. Environmental Protection Agency’s Mercury and Air Toxics Standards (MATS). The compliance date for MATS is April 16, 2015. In order to complete the work associated with this project and remove MATS applicability for Units 1–4, the utility requested an extension of compliance with that MATS deadline. The department granted this request in March 2013.
U.S. Energy Information Administration data shows Gaston getting coal in 2013 from Alabama coal producers Walter Energy (North River longwall mine), Twin Pines Coal and Alabama Coal, plus coal from Colorado from the Elk Creek longwall mine of Oxbow Mining, and coal from Indiana from the Gibson deep mine of Alliance Coal.
Said the Alabama Power website in a section on environmental initiatives: “About a quarter of Alabama Power’s generation is completely emission-free, thanks to the company’s use of hydropower and nuclear energy. As for the company’s fleet of fossil-fueled plants, emissions of nitrogen oxides (NOx) are down 78 percent since 1996, while emissions of sulfur dioxide (SO2) have dropped by 76 percent. Alabama Power also recently switched the primary fuel source at its Plant Gadsden from coal to natural gas and plans to do the same for four of its Plant Gaston units to further reduce emissions and continue providing affordable energy to its customers.”
GenerationHub data shows that there is a fifth coal unit at Gaston, Unit 5, with a capacity of 952 MW (nameplate). The Alabama Power website shows that an SO2 scrubber was added on Gaston Unit 5 in 2010, selective catalytic reduction for NOx control in 2006, and that baghouses for particulate control are planned for 2016.