### AECC Bailey and McClellan NOx BART report - EPA comments Dayana Medina to: pettyjohn 10/31/2012 09:53 AM

Cc: mac, rheaume, "Brown, Derrick", Spencer, Stuart, Stuart, "Davis, Anthony", Guy Donaldson, Michael Feldman, Joe Kordzi, Barbara

Nann

From: Dayana Medina/R6/USEPA/US

To: pettyjohn@adeq.state.ar.us

Cc: mac@adeq.state.ar.us, rheaume@adeq.state.ar.us, "Brown, Derrick" <brownd@adeq.state.ar.us>, Spencer, Stuart <SPENCER@adeq.state.ar.us>, Stuart <SPENCER@adeq.state.ar.us>, "Davis, Anthony" <DavisA@adeq.state.ar.us>, Guy

Hi Mary,

Here are Region 6's comments on AECC's draft NOx BART analysis report for Bailey and McClellan. Our goal is to work with the State to receive a revised SIP that is approvable and defensible. As discussed yesterday, we believe that additional documentation and clarification on certain parts of AECC's BART report are needed for a defensible analysis. Please see our comments below.

1. Given the current uncertainty surrounding the Transport Rule and CAIR, our review and comments on the report are limited only to AECC’s source-specific NOx BART analysis for the
two units.

2. In Table 1-2, AECC assumes SCR has 85% removal efficiency for the gas firing scenario and 75% removal efficiency for the oil firing scenario. AECC also assumes SNCR would result in an additional 10% control over LNB/OFA. We believe these controls are capable of achieving greater removal efficiency. We also believe that AECC’s calculations of the cost of these controls are potentially overestimated, as these controls have been found to be cost-effective at comparable EGUs. However, we believe that after conservatively adjusting for these considerations, it does not appear that the potential visibility benefit that would result from the installation of these post-combustion controls would justify their expense. Therefore, we are not further discussing issues related to the analysis for post-combustion controls and our comments below focus on LNB, OFA, and FGR.

3. AECC should insert an introductory section at the beginning of the document that provides basic information about the facilities and the purpose of the report, as was done in the SO2 and PM BART analysis report.

4. Section 1.3 of the NOx BART analysis, which describes all potential controls, is not sufficiently documented. Information provided on the level of control that is achievable from installation of combustion controls is outdated and appears to the obtained from general reference materials. The RHR provides that in establishing source specific BART emission limits, the State should identify and consider in the BART analysis the maximum level of emission reduction that has been achieved in other recent retrofits at existing sources in the source category (64 FR 35740). As such, AECC should provide additional documentation on the level of control the combustion controls are capable of achieving. Suggested sources for this information include vendor quotes, emissions and control data from EPA’s CAMD databases ( http :// ampd

. epa

. gov / ampd / ), EPA’s RACT/BACT/LAER Clearinghouse ( http :// cfpub

. epa

. gov / RBLC / ), and the U.S. Energy Information Administration ( http :// www

. eia

. gov / ).

5. AECC selected 2009-2011 as the new baseline period. However, as shown in the attached spreadsheet, the actual annual NOx emissions and average NOx emission rates were considerably higher in 2001-2003 than in AECC’s new baseline period. In addition, the average annual operating hours at the Bailey unit during 2001-2003 were substantially greater than duringthe new baseline period and the annual fuel oil usa g e at both units from 2001-2003 was considerably higher (approximately 35 times higher at Bailey and 9 times higher at McClellan) than during AECC’s new baseline period. AECC should provide an explanation for why a new baseline period was selected. It does not appear that the permitted NOx emission limits have been revised or that federally enforceable limits have been established for the number of annual operating hours or fuel oil usage for each unit consistent with the new baseline. We believe it is appropriate for AECC to use 2001-2003 as the baseline period in the NOx BART analysis, unless an adequate justification is provided for using a new 2009-2011 baseline period.

6. In the event that AECC provides an adequate justification for using the new 2009-2011 baseline period and we find it appropriate, we have questions regarding the baseline NOx emission rates provided in Table 1-2. The table shows that the NOx emission rate from the new baseline period is 0.29 lb/MMBtu for natural gas firing and 0.30 for fuel oil firing at Bailey Unit 1 and 0.31 lb/MMBtu for natural gas firing and 0.50 for fuel oil firing at McClellan Unit 1. As shown in the attached spreadsheet, data we obtained from the Clean Air Markets Division (CAMD) shows that the average NOx emission rate from 2009-2011 was 0.196 at Bailey Unit 1 and 0.234 lb/MMBtu at McClellan Unit 1. AECC should provide an explanation for why the 2009-2011 NOx emission rates shown in Table 1-2 are higher than those obtained from CAMD for the same time period.

7. Section 1.5.1 of the BART analysis report explains that the controlled annual emission rate is based on the lb/MMBtu level believed to be achievable by the control technology multiplied by the baseline heat input to the boiler in MMBtu/yr, and that the baseline heat input per fuel is based on the average fuel usage from 2007-2011 multiplied by the average heat content of that particular fuel from that same time period. AECC should provide under section 1.5.1 annual fuel usage data and information on the average heat content of each fuel type to allow the public an opportunity to
review that data.

8. There appear to be several errors in Table 1-2. For instance, AECC assumes 85% SCR control for natural gas firing and 75% SCR control for fuel oil firing. Although we question the baseline NOx emission rates listed in Table 1-2 as well as the removal efficiencies assumed by AECC, we note that 85% control from a baseline of 0.29 lb/MMBtu at Bailey Unit 1 results in a controlled emission rate of 0.0435 (AECC rounded off to 0.04 lb/MMBtu) and 75% control from a baseline of
0.30 lb/MMBtu results in a controlled emission rate of 0.075 lb/MMBtu (not 0.05 lb/MMBtu as shown in Table 1-2). Similarly, at McClellan Unit 1, 85% control from a baseline of 0.31 lb/MMBtu results in a controlled emission rate of 0.0465 lb/MMBtu (not 0.03 lb/MMBtu as shown in Table 1-2) and 75% control from a baseline of 0.50 lb/MMBtu results in a controlled emission rate of 0.125 lb/MMBtu (AECC rounded off to 0.12 lb/MMBtu). AECC should revise Table 1-2 and correct any calculation errors.

9. The combustion controls AECC is considering are LNB, OFA, and FGR. However, the costing information for OFA and FGR is not included in Appendix A or anywhere else in the BART analysis report. AECC should provide this information along with an analysis of the visibility impact of FGR. It is unclear why in section 1.3.1 of the BART analysis, FGR is identified as a technically feasible control option, but the remaining steps of the analysis are not completed for FGR. AECC should reintegrate consideration of this control in its BART analysis.

10. On page 1-8, AECC states that the capital costs of controls were based on vendor estimates and published calculation methods. AECC should provide those vendor quotes for all combustion controls considered, redacted if necessary. AECC should document these estimates following
EPA’s Control Cost Manual.

11. It appears that AECC based its cost analysis of LNB on a 2005 ERG report prepared for the
WRAP that was based on coal fired EGU data. AECC should demonstrate that the data and costing methods it used are appropriate and applicable to the Bailey and McClellan units, which combust mainly natural gas and also fuel oil. In addition, AECC should make an attempt to incorporate in the cost analysis site-specific costing information and experience gained from theinstallation of similar controls at units comparable to those at Baile y and McClella n

.

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