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combustion controls is outdated and appears to the obtained from general reference materials.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 during 
the new baseline period and the annual fuel oil usage 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 the 
installation of similar controls at units comparable to those at Bailey and McClellan.

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