### Region 6 comments on AEP Flint Creek updated BART report Dayana Medina to: pettyjohn 02/08/2013 01:06 PM Cc: Michael Feldman, Guy Donaldson

From: Dayana Medina/R6/USEPA/US To: pettyjohn@adeq.state.ar.us Cc: Michael Feldman/R6/USEPA/US@EPA, Guy Donaldson/R6/USEPA/US@EPA
Hi Mary, Thank you for the opportunity to comment on the updated draft BART report for AEP Flint Creek. Here are Region 6's comments, which we'd be happy to discuss with you.

Comments on the AEP/SWEPCO Flint Creek January 2013 BART Analysis:
SO 2 Control Efficiency For NID, AEP/SWEPCO assumes a control efficiency of 92%, resulting in a controlled emission rate of 0.06 lbs/MMBtu. However, testimony of Mr. Christian T. Beam of AEP (attached below) before the Arkansas PUC, 2-8-12, page 22, indicates that for the NID system proposed for Flint Creek, "NID technology can attain higher levels of SO2 reduction, with vendor guarantee removal rates of 98% compared to maximum removal rates of 95% for SDA and other DFGD technologies. The higher removal rate for NID allows for greater fuel flexibility for the Flint Creek site to meet environmental compliance limits." We have seen literature from the NID vendor that substantiates a 98% removal efficiency. A BART evaluation requires that, "in analyzing the technology you take into account the most stringent emission control level that the technology is capable of achieving." (70 FR 39166). Therefore, AEP/SWEPCO should demonstrate this requirement has been met. We further note that AEP/SWEPCO has provided little documentation for the capital and operating costs it presents for the various SO2 BART control options, while selecting the less stringent control option. It is also unclear why in the January 2013 BART report, the estimated capital cost in AEP’s cost analysis for the NID system was increased by more than $118 million when compared to the estimated cost in the September 2012 version of the BART report. Modeling and Emission Estimates : To estimate sulfuric acid emissions to model for the baseline and control cases, all inorganic PM was assumed to be SO4. This assumption and assumptions of SO4 reductions due to controls impacts the baseline modeling as well as the visibility benefit from WFGD when compared to NID. We recommend that sulfuric acid emissions from power plants are calculated by estimating the amount of H2SO4 produced and the amount of H2SO4 removed by control equipment using information from the Electric Power Research Institute (EPRI) Estimating Total Sulfuric Acid Emissions from Stationary Power Plants: Version 2010a. EPRI, Palo Alto, CA: 2010. 1020636. consistent with the methodology detailed in the Technical support document that accompanies the Oklahoma FIP. These calculations rely on assumed values for the amount of fuel sulfur converted to SO2, the amount of SO2 oxidized to SO3, and the amount of H2SO4 lost to (or mitigated by) the air pre-heater and applicable control equipment, such as baghouses, and FGDs.
It is also unclear how total PM10 emission rates were determined for the NID and WFGD control cases. The modeled PM10 emission rates for NID and WFGD are approximately 0.002lb/MMBtu and 0.0125 lb/MMBtu. Furthermore, there is an error in the PM speciation calculation obtained by using the NPS spreadsheets.Emission factors within these tables var y b y the t y pe of emission control equipment downstream and are functions of the coal’s sulfur and ash content. It appears that calculated PM speciation used the placeholder values present in the worksheets, rather than inputting specific data for the type of coal used as given in footnote 8 on page 4-1 of the BART analysis. The PM speciation worksheets for the controlled cases should be provided in addition to the corrected basecase worksheet.
NOx BART : For NOx BART, AEP/SWEPCO assumes an emission rate of 0. 23 lbs/MMBtu, using LNB/OFA, in the event CAIR cannot be relied upon. However, the same testimony referenced above states, "If low NOX burners and over-fire air are installed on Flint Creek, the NOx rate is expected to drop to the 0.18 to 0.22 lbs/mmbtu range." A similar claim is made on page 6-4 of the BART report. As above, AEP/SWEPCO should demonstrate that the most stringent emission control level for this technology is analyzed. We further note that AEP/SWEPCO has provided little documentation for the capital and operating costs it presents for the various NOx BART control options.
PM BART : EPA approved the current ESP as BART for PM. IF AEP/SWEPCO upgrades the PM controls, the PM emission limit should be adjusted accordingly.

Thank you, Dayana Medina U.S. Environmental Protection Agency, Region 6 Multimedia Planning and Permitting Division Air Planning Section (6PD-L) 1445 Ross Avenue Dallas, TX 75202 214-665-7241 medina.dayana@epa.gov