Region 6 Comments on Entergy Lake Catherine BART Report 

03/29/13 

1. Fuel Oil Firing Scenario 

 The BART report states that “If conditions change such that it becomes economic to burn 

fuel oil, a five factor analysis will be submitted for approval in the SIP. The combustion 

of fuel oil [at Unit 4] would not occur until final SIP approval.” ADEQ should ensure that 

the source’s air permit is revised or that language is included in the Arkansas BART rule 

to capture the condition that Unit 4 will not burn fuel oil until BART for all pollutants for 

the fuel oil firing scenario is approved into the SIP. 

 

2. NOx Baseline Emissions/Controlled Emission Rates 

 In reviewing the draft NOx BART analysis there are a number of issues with how the 

baseline emissions the cost and effectiveness of various control technologies are 

estimated that make it difficult to evaluate whether a reasonable decision is being 

recommended for BART. These issues are outlined below. We would welcome the 

opportunity to discuss further. 

 The baseline annual emission rate that is used to estimate the control efficiency of NOx 

controls and to calculate the annual tons reduced in the cost effectiveness calculations is 

0.48 lb/MMBtu, based on the 24-hr maximum emission rate during the baseline period. 

However, based on CEMS data from CAMD (see table below), it appears that the 

average annual NOx emission rate from the 2001-2003 baseline period is 0.18 

lb/MMBtu, and the maximum is 0.198 lb/MMBtu. The maximum 30-day rolling average 

during the baseline period is 0.377 lb/MMBtu; however, this is driven by one unusually 

high day. The maximum 30-day rolling average that excludes the highest day falls below 

0.3 lb/MMBtu (see graph below), and the second highest 24-hr emission rate during the 

baseline period is 0.346 lb/MMBtu. Based on this information, presented in the table and 

graph below, it appears that using 0.48 lb/MMBtu as the baseline may not be 

representative of actual emissions from the baseline period and that the emission rates 

achievable by the NOx controls are potentially lower than what was evaluated in the 

BART analysis. Appendix Y to Part 51 provides the following: 

“The baseline emissions rate should represent a realistic depiction of anticipated 

annual emissions for the source. In general, for the existing sources subject to 
BART, you will estimate the anticipated annual emissions based upon actual 

emissions from a baseline period” (Appendix Y to Part 51, section IV.D.4.d). 

ADEQ should ensure that the baseline emission rate that is used is in accordance with 

Appendix Y to Part 51. In addition, 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). ADEQ should ensure that this 

requirement has been met for all NOx controls evaluated. We note that in 2000, we 

approved into the Texas SIP a NOx emission limit of 0.10 lb/MMBtu based on a daily 

average for utility boilers located in the Beaumont/Port Arthur area (65 FR 64148). In the 

supporting documentation included in the SIP submittal, Texas explained that since the 

majority of the boilers affected by that limit were tangentially-fired gas boilers, it was 

expected that the limit would be achievable with combustion modification techniques. 

Lake Catherine Unit 4 is the same type of boiler as this. Please ensure that the controlled 

emission rates evaluated for all NOx controls reflect the most stringent emission level 

achievable by that technology. 

Year Operating

Time

Avg. NOx Rate

(lb/MMBtu)

NOx

(tons)

Heat Input

(MMBtu)

Capacity

factor*

2001 6987.75 0.1943 1724.201 1.443E+07 28.2%

2002 5651.25 0.198 1421.07 1.242E+07 24.2%

2003 3972 0.1465 540.117 5.770E+06 11.3%

2004 1534.22 0.1238 139.971 1.904E+06 3.7%

2005 2058.55 0.1339 195.917 2.413E+06 4.7%

2006 314.05 0.1422 25.58 2.917E+05 0.6%

2007 415.91 0.4014 89.304 4.121E+05 0.8%

2008 883.79 0.1751 113.288 1.161E+06 2.3%

2009 823 0.2666 191.427 1.416E+06 2.8%

2010 1488.69 0.1428 150.545 1.800E+06 3.5%

2011 1303.19 0.1471 145.149 1.499E+06 2.9%

2012 4312.99 0.1881 927.544 7.346E+06 14.3%

* Calculated as:  annual heat input / (5850 MMBtu/hr *8760 hr/yr)
 The NOx removal efficiency of BOOS assumed in the BART analysis is based on an 

estimate from Entropy Technology and Environmental Consultants, while the removal 

efficiencies of FGR, LNB/SOFA, SCR, and SNCR are based on estimates from Sargent 

& Lundy. Please provide documentation of these estimates. 

 Entergy assumes an historical 10 percent capacity factor in determining BART. EPA 

agrees that Unit 4 historically operated at less than a 10 percent capacity factor during the 

2004-2011 period. However, the unit’s capacity factor for the 2001-2003 baseline period 

should be used for the BART analysis. Based on our calculations, the average annual 

capacity factor during 2001-2003 was 21.2% (see table above). Otherwise, a 10 percent 

capacity factor may be assumed in the BART analysis as long as this is made into an 

enforceable limit. This is important because in the cost effectiveness calculations, 

Entergy estimates the annual tons removed from baseline annual emissions that are 

calculated by multiplying the baseline emission rate by an annual heat input that reflects 

Unit 4’s capacity factor. Therefore, using a 10 percent capacity factor underestimates the 

annual tons reduced for all the control scenarios. As such, the NOx controls evaluated are 

potentially more cost effective than estimated by Entergy. As Appendix Y to Part 51 

states: 

 “The baseline emissions rate should represent a realistic depiction of 

anticipated annual emissions for the source. In general, for the existing 

sources subject to BART, you will estimate the anticipated annual 

emissions based upon actual emissions from a baseline period. When you 
project that future operating parameters (e.g., limited hours of operation or 

capacity utilization, type of fuel, raw materials or product mix or type) 

will differ from past practice, and if this projection has a deciding effect in 

the BART determination, then you must make these parameters or 

assumptions into enforceable limitations. In the absence of enforceable 

limitations, you calculate baseline emissions based upon continuation of 

past practice” (Appendix Y to Part 51, section IV.D.4.d). 

3. NOx Cost Evaluation 

 For the cost estimate for the BOOS control option, please explain why the first year 

O&M costs are considerably higher than for subsequent years ($871,000 vs. $21,000). 

 The estimates for the capital costs for LNB/SOFA, LNB/SOFA+SNCR, and 

LNB/SOFA+SCR; the first-year O&M costs for BOOS; the fixed O&M costs for all NOx 

control options; and the variable O&M costs for BOOS, SNCR (alone), and SCR (alone) 

are based on the “NOx Control Technology Cost and Performance Study” provided by 

Sargent & Lundy. Please provide a copy of this document. 

 The estimates for the variable O&M costs for LNB/OFA are based on an equation 

documented in the 2005 Eastern Research Group report “Analysis of Combustion 

Controls for Reducing NOx Emissions from Coal-fired EGUs in the WRAP Region.” As 

this report was based on coal fired EGU data, ADEQ should demonstrate that the data 

and costing methods used are appropriate and applicable to Lake Catherine Unit 4, which 

does not combust coal. 

 The BART evaluation assumes a 15 year actual service life for all NOx control options. 

Footnote 1 under the BOOS cost estimate in Appendix A states that implementation of 

BOOS would not require capital additions. Since it appears that BOOS would not require 

the installation of additional equipment, please explain why a 15 year actual service life 

was assumed in the cost evaluation. We believe that an anticipated 30 year equipment life 

is more appropriate to use in the cost analysis for all the NOx control options. Unless 

proper documentation is provided to demonstrate that the anticipated equipment life is 

limited to 15 years, ADEQ should ensure that the cost analysis assumes a 30 year 

equipment life for all BART determinations. 

 The cost evaluations of all NOx control scenarios, with the exception of BOOS, includes 

AFUDC costs. AFUDC costs are not allowed under the EPA Control Cost Manual 

(CCM), and therefore should not be included in the cost evaluation.