## BART F IVE 

## F ACTOR 

## A NALYSIS



## F LINT 

## C REEK 

## P OWER 

## P LANT



## G ENTRY 

## , A RKANSAS 

## (AFIN 04

- 00107)

Prepared By:

T RINITY C ONSULTANTS , I NC

.

120 East Sheridan, Suite 205 Oklahoma City, Oklahoma 73104 (405) 228

- 3292

T RINITY C ONSULTANTS , I NC

.

977 Ridge Drive, Suite 380

Lenexa, Kansas 66219 (913) 894

- 4500

In conjunction with:

A MERICAN E LECTRIC P OWER S ERVICE C ORPORATION PO Box 660164 Dallas, Texas 72566 (214) 777

- 1113

for the

S OUTHWESTERN E LECTRIC P OWER C OMPANY F LINT C REEK P OWER P LANT

21797 SWEPCO Plant Road

Gentry, A rkansas 72734

Trinity Project No s . 113701.0022 & 123701.0038

March 201 3

Version 3

## T ABLE OF 

## C ONTENTS



### 1. E XECUTIVE 

### S UMMARY



### ................................ ................................ ........................ 1

- 1

2. I NTRODUCTION AND 

### B ACKGROUND



### ................................ ................................ .... 2

- 1

3. M ODELING 

### M ETHODOLOGIES AND 

### P ROCEDURES



### ................................ ............. 3

- 1 3.1 CALMET AND 

### CALPUFF

................................ ................................ ................... 3

- 1 3.2 CALPOST

................................ ................................ ................................ ............ 3

- 1

4. E XISTING 

### E MISSIONS AND 

### V ISIBILITY 

### I MPAIRMENT



### ................................ ......... 4

- 1 4.1 NO X 

### , SO 2 

### , AND 

### PM 10 

### B ASELINE 

### E MISSION 

### R ATES



### ................................ ............... 4

- 1 4.2 B ASELINE 

### V ISIBILITY 

### I MPAIRMENT



### ................................ ................................ ....... 4

- 2

5. SO 2 

### BART E VALUATION



### ................................ ................................ .................... 5

- 1 5.1 I DENTIFICATION OF 

### A VAILABLE 

### R ETROFIT 

### SO 2 

### C ONTROL 

### T ECHNOLOGIES



### .......... 5

- 1 5.2 E LIMINATE 

### T ECHNICALLY 

### I NFEASIBLE 

### SO 2 

### C ONTROL 

### T ECHNOLOGIES



### ................ 5

- 1
5.2.1 D RY S ORBENT I NJECTION

................................ ................................ ................... 5

- 1
5.2.2 D RY S CRUBBER

................................ ................................ ................................ ... 5

- 2
5.2.3 W ET S CRUBBER

................................ ................................ ................................ .. 5

- 2 

### 5.3 R ANK OF 

### T ECHNICALLY 

### F EASIBLE 

### SO 2 

### C ONTROL 

### O PTIONS BY 

### E FFECTIVENESS



### .. 5

- 3 5.4 E VALUATION OF 

### I MPACTS FOR 

### F EASIBLE 

### SO 2 

### C ONTROLS



### ................................ ..... 5

- 3
5.4.1 C OST OF C OMPLIANCE

................................ ................................ ........................ 5

- 4
5.4.2 E NERGY I MPACTS AND N ON

- A IR Q UALITY I MPACTS

................................ ......... 5

- 7
5.4.3 R EMAINING U SEFUL L IFE

................................ ................................ ................... 5

- 7 

### 5.5 E VALUATION OF 

### V ISIBILITY 

### I MPACT OF 

### F EASIBLE 

### SO 2 

### C ONTROLS



### ...................... 5

- 7 5.6 P ROPOSED 

### B ART FOR 

### SO 2


### ................................ ................................ ................... 5

- 10
5.6.1 C OMPARATIVE SO 2 BART D ETERMINATIONS

................................ ................. 5

- 10



### 6. NO X 

### BART E VALUATION



### ................................ ................................ ................... 6

- 1 6.1 C ROSS



### - S TATE 

### A IR 

### P OLLUTION 

### R ULE 

### , ................................ ................................ ... 6

- 1 C LEAN 

### A IR 

### I NTERSTATE 

### R ULE 

### , AND 

### BART

................................ ................................ ...... 6

- 1 6.2 I DENTIFICATION OF 

### A VAILABLE 

### R ETROFIT 

### NO X 

### C ONTROL 

### T ECHNOLOGIES



### ......... 6

- 2 6.3 E LIMINATE 

### T ECHNICALLY 

### I NFEAS IBLE 

### NO X 

### C ONTROL 

### T ECHNOLOGIES



### ............... 6

- 2
6.3.1 C OMBUSTION C ONTROLS

................................ ................................ .................... 6

- 3
6.3.1.1 Flue Gas Recirculation (FGR)

................................ ............................. 6

- 3
6.3.1.2 Overfire Air (OFA)

................................ ................................ .............. 6

- 3
6.3.1.3 Low NO X Burners

................................ ................................ ................ 6

- 3
6.3.2 P OST C OM BUSTION C ONTROLS

................................ ................................ .......... 6

- 4
6.3.2.1 Selective Catalytic Reduction

................................ .............................. 6

- 4
6.3.2.2 Selective Non

- Catalytic Reduction

................................ ...................... 6

- 4 

### 6.4 R ANK OF 

### T ECHNICALLY FEASIBLE 

### NO X 

### C ONTROL 

### O PTIONS BY 

### E FFECTIVENESS



### .. 6

- 5 6.5 E VALUATION OF 

### I MPACTS FOR 

### F EASIBLE 

### NO X 

### C ONTROLS



### ................................ ... 6

- 5

Southwestern Electric Power Company i Trinity Consultants BART Analysis

– Flint Creek6.5.1 C OST OF C OMPLIANCE

................................ ................................ ........................ 6

- 6
6.5.2 E NERGY I MPACTS & N ON

- A IR I MPACTS

................................ .......................... 6

- 10
6.5.3 R EMAINING U SEFUL L IFE

................................ ................................ ................. 6

- 10 

### 6.6 E VALUATION OF 

### V ISIBILITY 

### I MPACT OF 

### F EASIBLE 

### NO X 

### C ONTROLS



### ................... 6

- 10 6.7 P ROPOSED 

### B ART FOR 

### NO X


### ................................ ................................ .................... 6

- 1

7. PM 10 

### BART E VALUATION



### ................................ ................................ .................. 7

- 1

A PPENDIX 

### A

................................ ................................ ................................ ................................ .

A PPENDIX 

### B

................................ ................................ ................................ ................................ .

A PPENDIX 

### C

................................ ................................ ................................ ................................ .

Southwestern Electric Power Company ii Trinity Consultants BART Analysis

– Flint Creek

## L IST OF 

## T ABLES

T ABLE 1

- 1. E XISTING V ISIBILITY I MPAIRMENT A TTRIBUTABLE TO SN

- 01 (2001

- 2 003)

................... 1

- 1

T ABLE 3

- 1. A NNUAL A VERAGE B ACKGROUND C ONCENTRATION

................................ ..................... 3

- 2

T ABLE 3

- 2. F L (RH) L ARGE RH A DJUSTMENT F ACTORS

................................ ................................ ..... 3

- 3

T ABLE 3

- 3. F S (RH) S MALL RH A DJUSTMENT F ACTORS

................................ ................................ ..... 3

- 3

T ABLE 3

- 4. F SS (RH) S EA S ALT RH A DJUSTMENT F ACTORS

................................ ............................... 3

- 3

T ABLE 4

- 1. B ASELINE M AXIMUM 24

- HOUR SO 2 , NO X , AND PM 10 E MISSION RATES ( AS H OURLY E QUIVALENTS )

................................ ................................ ................................ ....................... 4

- 1

T ABLE 4

- 2. B ASELINE V ISIBILITY I MPAIRMENT A TTRIBUTABLE TO SN

- 01 B OILER (2001

- 2003)

..... 4

- 2

TABLE 5

- 1. A VAILABLE SO 2 C ONTROL T ECHNOLOGIES FOR SN

- 01

................................ .................. 5

- 1

T ABLE 5

- 2. C ONTROL E FFECTIVENESS OF T ECHNICALLY F EASIBLE SO 2 C ONTROL T ECHNOLOGIES 5

- 3

T ABLE 5

- 3. S UMMARY OF C OST E FFECTIVENESS FOR SN

- 01 SO 2 C ONTROLS

................................ ... 5

- 5

T ABLE 5

- 4. D OLLAR PER D ECIVIEW C OST E FFECTIVENESS FOR SN

- 01 SO 2 C ONTROLS OF W ET S CRUBBING

................................ ................................ ................................ ............................. 5

- 6

T ABLE 5

- 5. D OLLAR PER D ECIVIEW C OST E FFECTIVENESS FOR SN

- 01 SO 2 C ONTROLS OF NIDS

.... 5

- 6

T ABLE 5

- 6. S UMMARY OF E MISSION R ATES M ODELED TO R EFLECT SO 2 C ONTROLS

........................ 5

- 8

T ABLE 5

- 7. S UMMARY OF M ODELED I MPACTS FROM SO 2 C ONTROL V ISIBILITY I MPACT A NALYSIS

FOR SN

- 01 (2001

- 2003)

................................ ................................ ................................ .......... 5

- 9

T ABLE 6

- 1. A VAILABLE NO X C ONTROL T ECHNOLOGIES FOR SN

- 01

................................ ................ 6

- 2

T ABLE 6

- 2. C ONTROL E FFECTIVENESS OF T ECHNICALLY F EASIBLE NO X C ONTROL T ECHNOLOGIES 6

- 5

TABLE 6

- 3. S UMMARY OF C OST E FFECTIVENESS FOR SN

- 01 NO X C ONTROLS

................................ ... 6

- 8

TABLE 6

- 4. D OLLAR PER D ECIVIEW C OST E FFECTIVENESS FOR SN

- 01 NO X C ONTROL U SING LNB/OFA

................................ ................................ ................................ ............................... 6

- 9

TABLE 6

- 5. D OLLAR PER D ECIVIEW C OST E FFECTIVENESS FOR SN

- 01 NO X C ONTROL U SING LNB/OFA P LUS SNCR

................................ ................................ ................................ .......... 6

- 9

TABLE 6

- 6. D OLLAR PER D ECIVIEW C OST E FFECTIVENESS FOR SN

- 01 NO X C ONTROL U SING SCR

. 6

- 9

T ABLE 6

- 7. S UMMARY OF E MISSION R ATES M ODELED TO R EFLECT LNB/OFA FOR NO X C ONTROL 6

- 11

Southwestern Electric Power Company iii Trinity Consultants BART Analysis

– Flint CreekT ABLE 6

- 8. S UMMARY OF E MISSION R ATES M ODELED TO R EFLECT SCR FOR NO X C ONTROL

....... 6

- 11

T ABLE 6

- 9. S UMMARY OF E MISSION R ATES M ODELED TO R EFLECT LNB/OFA + SNCR FOR NO X C ONTROL

................................ ................................ ................................ .............................. 6

- 11

T ABLE 6

- 10. S UMMARY OF V ISIBILITY I MPROVEMENT A SSOCIATED WITH NO X C ONTROL S YSTEM ON SN

- 01 (2001

- 2003)

................................ ................................ ................................ ............... 6

- 12

Southwestern Electric Power Company iv Trinity Consultants BART Analysis

– Flint Creek

## 1. E XECUTIVE 

## S UMMARY

This report documents the determination of the Best Available Retrofit Technology (BART) for Southwestern Electric Power Company’s (SWE P CO ’s ) 1 electric generating unit at the Flint Creek
P ower P lant ( SN

- 01 )

. SN

- 01 is a dry bott om wall

- fired boiler with a nominal design maximum heat input of 6,324 million British thermal units per hour (MMBtu/hr) that burn s primarily low sulfur western coal

. The unit has a nominal generating capacity rating of 558 MW and commenced commercial ope ration in 1978. It is currently equipped with an electrostatic precipitator and low NO X burners.

Based on modeling performed for this analysis, c umulative emissions of nitrogen oxides (NO X ), sulfur dioxide (SO 2 ), and particulate matter with a mean diamet er smaller than ten microns (PM 10 ) from SN

- 01 are predicted to cause or contribute greater than 0.5 deciviews (∆dv) of visibility impairment in f our Class I Areas: Caney Creek Wilderness (CACR), Upper Buffalo Wilderness (UPBU), Hercules Glades Wilderness (HERC), and Mingo Wilderness (MING).

A summary of the existing visibility impairment attri butable to SN

- 01 based on the default natural conditions is provided in Table 1

- 1. T he visibility impairment summarize d in Table 1

- 1 is based on modeling conduct ed by Trinity Consultants (Trinity) using actual emissions data based on a combination of stack testing and CEMS as further described in Section 4 of this report.

T ABLE 1

- 1. E XISTING V ISIBILITY I MPAIRMENT A TTRIBUTABLE TO SN

- 01 (2001

- 2003)

Caney Creek Wild erness Upper Buffalo Wilderness Hercules Glades Wilderness Mingo Wilderness

98th

% ∆dv Days > 0.5 ∆dv 98th % ∆dv Days > 0.5 ∆dv 98th % ∆dv Days > 0.5 ∆dv 98th % ∆dv Days > 0.5 ∆dv

AEP Flint Creek SN

- 01 0.9 6 3 48 0.965 63 0.657 47 0.631 20

Trinity used the EPA’s BART guidelines in 40 CFR Part 51 2 and other recent EPA guidance to determine BART for SN

- 01

. Trinity conducted a five

- step analysis to determine BART that included the following:

1. Identif ying all available retrofit control technologies;

2. Elimin at ing technically infeasible control technologies;

3. Evaluat ing the control effectiveness of remaining control technologies;

4. Evaluating impacts and document the results ;
5. Evaluating visibility impacts

.

1 Southwestern Electric Power Company (SWEPCO) is an owner and the operator of the Flint Creek Power Plant, and a subsidiary of American Electric Power Company, Inc. (AEP). American Electric Power Service Corporation is a subsidiary of AEP that provides legal, accounting, engineering, and other services to the utility operating companies in the AEP system, including SWEPCO. SWEPCO and the Service Corporation are referred to generically as AEP throughout t his report. 2 The BART guidelines were published as amendments to the EPA’s RHR in 40 CFR Part 51, Section 308 on July
6 , 2005.

South western Electric P ower Company 1

- 1 Trinity Consultants BART Analysis

– Flint CreekBased on the five

- step analysis, the following were dete rmined to be BART:

▲ SO 2 – The BART analysis concluded that the installation of a dry scrubber and baghouse (e.g.

, Novel Integrated Deacidification System [ NIDS ] technology ) constitute s BART. The proposed BART emission rate for SO 2 is 0.06 lb/MMBtu calcula ted as a 30

- day rolling

average over each boiler operating day.

▲ NO X – EPA recently issued a final rule allowing states that are subject to the Cross

- State Air Pollution Rule (CSAPR) trading program for seasonal NO
x to rely on the reductions achieved thro ugh that trading program to satisfy the regional haze program requirements for units subject to BART. 3 Subsequently, CSAPR was vacated, and the Clean Air Interstate Rule (CAIR) remains in effect until an acceptable replacement rule is promulgated

. 4 If CS APR is upheld and implemented in Arkansas, SWEPCO will rely on CSAPR to satisfy its regional haze obligations at SN

- 01. If CSAPR is vacated and CAIR remains in effect, EPA’s prior determination that the reductions provided under CAIR’s seasonal NO X tradin g program provide greater visibility improvements than BART should allow SWEPCO to rely on the seasonal CAIR program to satisfy its NO X obligations under BART

. 5

In the alternative, SWEPCO has evaluated the cost

- effectiveness and visibility improvement of candidate BART controls at SN

- 01. The visibility improvements associated with the addition of NO X controls at SN

- 01 are minimal, and the cost

- effectiveness values for all control options exceed the values previously determined to be reasonable in EPA’s

p resumptive BART analysis. However, visibility improvements consistent with the modeled values used in CENRAP’s analysis for the interstate transport portion of Arkansas’s Regional Haze SIP obligations can be achieved with the addition of LNB/OFA , and this control option is proposed as BART for SN

- 01. If ADEQ determines that SWEPCO cannot rely on CAIR or CSAPR as an alternative to BART, the proposed BART emission rate for NO X at SN

- 01 is 0.23 lb/ MM Btu calculated as a 30

- day rolling average over each boiler operating day based on the application of LNB/OFA controls.

▲ PM 10 – A BART determination for PM 10 at SN

- 01 was approved in EPA’s March 12, 2012 final rule based on the existing ESP and a BART emission rate of 0.1 lb/MMBtu. 6

3 “Regional Haze: Revisions to Provisions Governing Alternatives to Source

- Specific Best Available Technology (BART) Determinati ons, Limited SIP Disapprovals and Federal Implementation Plans” 77 Fed. Reg. 33651 (June 7, 2012). 4 EME Homer City Generation, L.P., et al., v. United States Environmental Protection Agency, et al

., EPA . Case No. 11

- 1302 (and consolidated cases)

, Opinion ( D.C. Cir Aug. 21, 2012 ). 5 “Regional Haze Regulations and Best Available Retrofit Technology (BART) Guidelines, 70 Fed. Reg. 39104, 39143 (July 6, 2005). 6 “Approval and Promulgation of Implementation Plans; Arkansas; Regional Haze State Implementation Plan; Interstate Transport State Implementation Plan To Address Pollution Affecting Visibility and Regional Haze. Final Rule,” 77 Fed. Reg. 14604 (March 12, 2012).

South western Electric P ower Company 1

- 2 Trinity Consultants BART Analysis

– Flint Creek

## 2. I NTRODUCTION AND 

## B ACKGROUND

In the 1977 amendments to the Clean Air Act (CAA), Congress set a national goal to restore national parks and wilderness areas to pristine conditions by preventing any future, and remedying any existing

, man

- made visibility impairment. On July 1, 1999, th e U.S. EPA published the final Regional Haze Rule (RHR). The objective of the RHR is to restore visibility to pristine conditions in 156 specific areas across the U nited States known as Class I areas. The CAA defines Class I areas as certain national par ks (over 6

, 000 acres), wilderness areas (over 5

, 000 acres), national memorial parks (over 5

, 000 acres), and international parks that were in existence on August 7, 1977.

The RHR requires States to set goals that provide for reasonable progress towards ac hieving natural visibility conditions for each Class I area in their state. On July 6, 2005, the EPA published amendments to its 1999 RHR, often called the Best Available Retrofit Technology (BART) rule, which included guidance for making source

- specific BART determinations. The BART rule defines
BART

- eligible sources as sources that meet the following criteria:

(1) Have potential emissions of at least 250 tons per year of a visibility

- impairing pollutant, (2) Began operation between August 7, 1962 and August 7 , 1977, and (3) Are included as one of the 26 listed source categories in the guidance.

A BART

- eligible source is subject to BART if the source is “reasonably anticipated to cause or contribute to visibility impairment in any federal mandatory Class I area.” EPA has determined that a source is reasonably anticipated to cause or contribute to visibility impairment if the 98 th percentile visibility impacts from the source a re greater than 0.5 delta deciviews (∆dv) when compared against a natural background 7 . Air quality modeling is the tool that is used to determine a source’s visibility impacts.

Once it is determined that a source is subject to BART, a BART determinatio n must address air pollution control measures for the source. The visibility regulations define BART as follows:

“...an emission limitation based on the degree of reduction achievable through the application of the best system of continuous emission reduct ion for each pollutant which is emitted by...[a BART

- eligible source]. The emission limitation must be established on a case

- by

- case basis, taking into consideration the technology available, the cost of compliance, the energy and non air quality environmen tal impacts of compliance, any pollution control equipment in use or in existence at the source, the remaining useful life of the source, and the degree of improvement in visibility which may reasonabl y be anticipated to result from the use of such technol ogy.

Specifically, the BART rule states that a BART determination should address the following five statutory factors:

1. Existing controls
2. Cost of controls

7 Note this is a change from the ADEQ protocol with the 2006 CENRAP data, as the original a nalysis for Arkansas reviewed the “High First High” impacts rather than the 98 th percentile impacts

South western Electric P ower Company 2

- 1 Trinity Consultants BART Analysis

– Flint Creek3. Energy and non

- air quality environmental impacts
4. Remaining useful life of the source
5. Degree of visib ility improvement as a result of controls

Further, the BART rule indicates that the five basic steps in a BART analysis can be summarized as follows:

1. Identify all available retrofit control technologies;

2. Eliminate technically infeasible control technolog ies;

3. Evaluate the control effectiveness of remaining control technologies;

4. Evaluate impacts and document the results ;
5. Evaluate visibility impacts

A BART determination should be made for each visibility affecting pollutant (VAP) by following the five steps listed above for each VAP.

SN

- 01 meet s the three BART

- eligibility criteria described above , and the existing visibility impairment attributable to SN

- 01 is greater than 0.5 dv in at least one Class I area. Thu s, SN

- 01 is subject to BART. The details of the SN

- 01 existing/baseline emissions and the contribution of the emissions to visibility impairment can be found in Section 4 . The VAPs emitted by SN

- 01 include NO X , SO 2 , and PM 10 of various forms (filterable coarse particulate matter [PM
c ], filterable fine particle matter [PM f ], elemental carbon [EC], inorganic condensable particulate matter [IOR CPM] as sulfates [SO 4 ], and organic condensable particulate matter [OR CPM] also referred to as secondary organic aerosols [SOA]). The BART determinations for SO 2 , NO
x , and PM 10 can be found in Sections 5

, 6 , and 7 , respectively.

South western Electric P ower Company 2

- 2 Trinity Consultants BART Analysis

– Flint Creek

## 3. M ODELING 

## M ETHODOLOGIES AND 

## P ROCEDURES

This section summari z es the dispersion modeling methodologies and procedures applied in this BART analysis

. All dispersion modeling has been c onducted using the CALPUFF modeling system, consisting of the CALPUFF dispersion model, the CALMET meteorological data processor, and the CALPOST post

- processing program.

CALPUFF is a multi

- layer, multi

- species, non

- steady

- state puff dispersion model, w hich can simulate the effects of time and space varying meteorological conditions on pollutant transport, transformation,
and removal. CALPUFF uses three

- dimensional meteorological fields developed by the CALMET
model. In addition to meteorological data, several other input files are used by the CALPUFF model to specify source and receptor parameters. The selection and control of CALPUFF options are determined by user

- specific inputs contained in the control file. This file contains all of the necessary information to define a model run (e.g., starting date, run length, grid specifications, technical options, output options). CALPOST processes concentration, deposition, and visibility impacts based on pollutant specific concentrations predicted by CALPUF F.



## 3.1 CALMET AND 

## CALPUFF

The CALPUFF data and parameters are based on the 2005 BART modeling guidelines prepared for the Central States Regional Air Planning Association (CENRAP)

. The CALMET data and

param eters are based on the protocol included in Appendi x C. Note that the protocol included in Appendix C summarizes modeling methods and procedures that were followed to predict visibility impairment for several BART

- eligible sources located in Oklahoma as part of the BART analyses for these sources

. In add ition, several sources in Texas used the CALMET data that was generated in accordance with the protocol in their BART analyses.



## 3.2 CALPOST

The CALPOST visibility processing completed for this BART analysis is based on the October 2010 guidance from the Federal Land M anagers Air Quality Related Values Workgroup (FLA G)

. Th e 2010 FLAG guidance, which was issued in draft form on July 8, 2008 and published as final guidance in December 2010, makes technical revisions to the previous guidance issued in Decemb er 2000.

V isibility impairment is quantified using the light extinction coefficient ( b ext ), which is expressed in terms of the haze index expressed in deciview s (dv). The haze index ( HI ) is calculated as follows:

     

= 10 ln 10 (dv) ext b HI

T he impact of a source is determined by comparing the HI attributable to a source relative to estimated natural background conditions. The change in the haze index, in deciviews, also referred to as “delta dv,” or ∆dv, based on the source and background light extinction is based on the following equation:

Southwest ern Electric Power Company 3

- 1 Trinity Consultants BART Analysis

– Flint Creek

### ∆ dv = 10 * ln b b

b ext, backgroun d ext, source

ext, backgroun d 

### + 
   
  

The Interagency Monitoring of Protected Visual Environments (IMPROVE) workgroup adopted an equation for predicting light extinction as part of the 20 10 FLAG guidance ( often referred to as the

new IMPROVE equation ). The new IMPROVE equation i s as follows :



### = ext 

### b 

## ( ) ( ) 

## [ ] ( ) ( ) 

## [ ] ( ) 

## [ ] ( ) 

## [ ] [ ] [ ] [ ] [ ] [ ] ( ) 

## [ ] [ ]

2 Scattering Rayleigh specific Site Large Small Large 3 4 Small 3 4 Large 2 4 4 Small 2 4 4



### NO 33

. 0 Salt Sea 4

. 1 PMC 6

. 0 PMF 1 EC 10 OC 1

. 6 OC 8

. 2 NO NH 1

. 5 NO NH 4

. 2 SO NH 8

. 4 SO NH 2

. 2

+ + + + + + + + + +

+

− 

### b RH f RH f RH f RH f RH f

SS L S L S

Visibility impairment predictions for SN

- 01 relied upon in this BART analysis used the equation shown above. The use of this equation is referred to as “Method 8” in the CALPOST control file. The use of Method 8 requires that one of fiv e different “ modes ” be selected. The modes specify the approach for addressing the growth of hygrosc opic particles due to moisture in the atmosphere

.

“ Mode 5 ” has been used in this BART analysis. Mode 5 addresses moisture in the atmosphere in a similar way as to “Method 6”, where “Method 6” is specified as the preferred approach for use with
the old IM PROVE equation in the CENRAP BART modeling protocol.

CALPOST Method 8 , Mode 5 requires the following:

• Annual average concentrations reflecting natural background for various particles and for sea
salt

• Monthly RH factors for large and small ammonium sulf ates and nitrates and for sea salts

• Rayleigh scattering parameter corrected for site

- specific elevation

Tables 3

- 1 to Table 3

- 4 below show the values for the data described above that were input to CALPOST for use with Method 8, Mode 5. The values were o btained from the 2010 FLAG guidance.

T ABLE 3

- 1. A NNUAL A VERAGE B ACKGROUND C ONCENTRATION

Class I Area (NH 4 ) 2 SO 4 NH 4 NO 3 OM EC Soil CM Sea Salt Rayleigh (Mm - 1 ) Caney Creek Wilderness 0.23 0.1 1.8 0.02 0.5 3 0.03 11 Upper Buffalo Wilderness 0.23 0.1 1.8 0. 02 0.5 3 0.03 11

Hercules Glades Wilderness 0.23 0.1 1.8 0.02 0.5 3 0.02 11 Mingo Wilderness 0.23 0.1 1.83 0.02 0.51 3.05 0.04 12

Southwest ern Electric Power Company 3

- 2 Trinity Consultants BART Analysis

– Flint CreekT ABLE 3

- 2

. F L (RH) L ARGE RH A DJUSTMENT F ACTORS

Class I Area Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Caney Creek W ilderness 2.77 2.53 2.37 2.43 2.68 2.71 2.59 2.6 2.71 2.69 2.67 2.79
Upper Buffalo Wilderness 2.71 2.48 2.31 2.33 2.61 2.64 2.57 2.59 2.71 2.58 2.59 2.72

Hercules Glades Wilderness 2.7 2.48 2.3 2.3 2.57 2.59 2.56 2.6 2.69 2.54 2.57 2.72
Mingo Wilderness 2.73 2.52 2.34 2.28 2.53 2.6 2.64 2.67 2.71 2.56 2.56 2.73

T ABLE 3

- 3

. F S (RH) S MALL RH A DJUSTMENT F ACTORS

Class I Area Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Caney Creek Wilderness 3.85 3.44 3.14 3.24 3.66 3.71 3.49 3.51 3.73 3.72 3.68 3.88
Upper Buffalo Wilderness 3.73 3.33 3.03 3.07 3.54 3.57 3.43 3.5 3.71 3.51 3.52 3.74

Hercules Glades Wilderness 3.7 3.33 3.01 3.01 3.47 3.48 3.41 3.51 3.67 3.43 3.46 3.73
Mingo Wilderness 3.74 3.38 3.07 2.97 3.39 3.52 3.57 3.64 3.72 3.47 3.43 3.74

T ABLE 3

- 4

. F SS (RH) S EA S ALT RH A DJUSTMENT F ACTORS

Class I Area Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Caney Creek Wilderness 3.9 3.52 3.31 3.41 3.83 3.88 3.69 3.68 3.82 3.76 3.77 3.93
Upper Buffalo Wilderness 3.85 3.47 3.23 3.27 3.72 3.78 3.69 3.7 3.84 3.64 3.67 3.86

Hercules Glades Wilderness 3.86 3.51 3.23 3.22 3.66 3.72 3.69 3.73 3.81 3.57 3.65 3.88
Mingo Wilderness 3.92 3.58 3.3 3.19 3.58 3.72 3.8 3.82 3.85 3.61 3.66 3.9

Southwest ern Electric Power Company 3

- 3 Trinity Consultants BART Analysis

– Flint Creek

## 4. E XISTING 

## E MISSIONS AND 

## V ISIBILITY 

## I MPAIRMENT

This section summarizes t he existing (i.e. baseline) visibility impairment attributable to SN

- 01 based on air quality modeling conducted by Trinity.



## 4.1 NO X 

## , SO 2 

## , AND 

## PM 10 

## B ASELINE 

## E MISSION 

## R ATES

Table 4

- 1 summa ri zes the emission rates that were modeled for SO 2 , NO X , and PM 10 , inclu ding the speciated PM 10 emissions. T he SO 2 and NO X emission rates are the highest actual 24

- hour emission

rates based on 200 1

- 200 3 continuous emissions monitoring system (CEMS) data. The emission rates for the PM 10 species reflect the breakdown of the PM 10 determined from the National Park Service (NPS) “speciation spreadsheet” for Dry Bottom Boiler Burning Pulverized Coal using only ESP 8

. S pecifically, the NPS workbook shows the following baseline distribution for the PM species:

▲ Coarse PM (PM C ) = 33.8 %
▲ Fine soil (modeled as PM F ) = 26.1 %

▲ Fine elemental carbon (modeled as EC) = 1.0 %

▲ Organic condensable PM (modeled as SOA) = 7.8 %
▲ Inorganic condensable PM (modeled as SO 4 ) = 31.3 %

Per EPA’s request, 9 an SO 4 emission rate was independently calculated u sing an EPRI methodology
that considers the SO 2 to SO 4 conversion rate and SO 4 reduction factors for various downstream equipment. 10 This SO 4 rate was used in the modeling instead of the rate resulting from the NPS

based breakdown.

T ABLE 4

- 1

. B ASELINE M AX IMUM 24

- HOUR SO 2 , NO X , AND PM 10 E MISSION RATES ( AS H OURLY E QUIVALENTS )

SO 2 11 SO 4 NO X 12 PM c PM f SOA EC
Source (lb/hr) (lb/hr) (lb/hr) (lb/hr) (lb/hr) (lb/hr) (lb/hr)
SN

- 01 4,728.4 3.1 1,945.0 65.1 50.1 15.1 1.9

8 The NPS Workbook, "PC Dry Bottom ESP Example.xls" updated 03/2006, was obtained from the NPS website: http://www.nature.nps.gov/air/Permits/ect/index.cfm . The following parameters were input into the workbook for speciation
determination: total PM 10 emission rate of 192.5 lb/hr, heat value of 8,500 Btu/lb, sulfur content of 0.31 %, ash content of 4.9 %. 9 E

- mail from Dayana Medina (EPA) to Mary Pettyjohn ( ADEQ), February 8, 2013, and phone con versation with Michael Feldman (EPA), February 26, 2013. 10 Electric Power Research Institute (EPRI) Estimating Total Sulfuric Acid Emissions from Stationary Power Plants: Version 2010a. EPRI, Palo Alto, CA: 2010. 10206 36

. 11 Hourly rate was derived from EPA’s Clean Air Market Database (CAMD) daily rates of 113,482 lb/day.
12 Hourly rate was derived from EPA’s Clean Air Market Database (CAMD) daily rates of 46,680 lb/day.

Southwest ern Electric Power Company 4

- 1 Trinity Consultants BART Analysis

– Flint Creek

## 4.2 B ASELINE 

## V ISIBILITY 

## I MPAIRMENT

Trinity cond ucted modeling to determine the visibility impairment attributable to SN

- 01 in four Class I Areas: Caney Creek Wilderness (CACR), Upper Buffalo Wilderness (UPBU), Hercules Glades Wilderness (HERC), and Mingo Wilderness (MING) using the CALPUFF dispersion model.

Table 4

- 2 provides a summary of the modeled visibility im pairment attributable to SN

- 01 at CACR, UPBU, HERC, and MING based on the emission rates shown in Table 4

- 1

. Note that all of the CALMET, CALPUFF, and CALPOST modeling files are included a s part of the electronic files submitted with this document

.

T ABLE 4

- 2

. B ASELINE V ISIBILITY I MP AIRMENT A TTRIBUTABLE TO SN

- 01 B OILER (2001

- 2003)

Year Maximum (Δdv) 98th Percentile

(Δdv) No. of Day with Δdv ≥ 0.5 98th Percentile

% SO 4 98th Percentile

% NO 3 98th Percentile % PM 10 98th Percentile

% NO 2 Caney Creek Wilderness
2001 1.318 0.609 19 62.49 34.95 1.00 1.55
2002 1.165 0.689 10 60.43 35.25 1.72 2.60
2003 1.298 0.963 19 70.90 27.64 0.62 0.85 Upper Buffalo Wilderness
2001 1.732 0.955 22 53.0 1 45.08 1.16 0.74
2002 2.426 0.965 18 96.29 2.75 0.96 0.00
2003 1.394 0.670 23 89.90 5.4 2.74 1.97

Hercules Glades Wilderness
2001 1.418 0.643 19 76.92 22.4 0.69 0.00
2002 1.364 0.627 15 43.49 51.71 2.08 2.72
2003 2.103 0.657 13 47.91 49.69 1.19 1.2 1 Mingo Wilderness
2001 1.28 0.631 11 90.97 8.59 0.42 0.01
2002 0.841 0.424 6 93.66 5.94 0.40 0.00
2003 1.488 0.393 3 38.60 59.69 1.07 0.64

Southwest ern Electric Power Company 4

- 2 Trinity Consultants BART Analysis

– Flint Creek

## 5. SO 2 

## BART E VALUATION



## 5.1 I DENTIFICATION OF 

## A VAILABLE 

## R ETROFIT 

## SO 2 

## C ONTROL 

## T ECHNOLOGIES

Sulfur oxides, SO X , are g enerated during coal combustion from the oxidation of sulfur contained in the fuel. SO X emissions are almost entirely dependent on the sulfur content of the fuel and are generally not affected by boiler size or burner design. SO X emission s from convention al combustion systems are predominantly in the form of SO 2 . Since SO 2 is the predomina n t sulfu r compound emitted from SN

- 01 , the BART a nalysis is specific to emissions of SO 2 .
Step 1 of the top

- down control review is to identify available retrofit control options for SO 2 . The available SO 2 retrofit control technologies for SN

- 01 are summarized in Table 5

- 1 . The retrofit controls examined are limited to add

- on controls that eliminate SO 2 after it is formed

, as SN

- 01 currently uses a low sulfur fuel and wo uld not achieve significant additional reductions through alternative coal supplies.

TABLE 5

- 1

. A VAILABLE SO 2 C ONTROL T ECHNOLOGIES FOR SN

- 01

SO 2 Control Technologies

Dry Sorbent Injection Dry Scrubber

Wet Scrubber



## 5.2 E LIMINATE 

## T ECHNICALLY 

## I NFEASIBLE 

## S O 2 

## C ONTROL 

## T ECHNOLOGIES

Step 2 of the BART determination is to eliminate technically infeasible SO 2 control technologies that were identified in Step 1.



### 5.2.1 D RY 

### S ORBENT 

### I NJECTION

Dry sorbent injection involves the injection of a sorbent into the exhaust gas stream where
SO 2 reacts with and becomes entrained in the sorbent

. The stream is then passed through a particulate control device to remove the sorbent and entrained SO 2 . The process was developed as a lower cost F lue G as D esulfurization (FGD) option bec ause the mixing of
the SO 2 and sorbent occurs directly in the exhaust gas stream instead of in a separate tower. Depending on the residence time

, gas stream temperature, and limitations of the particulate control device, sorbent injection control efficien cy can range between 40 and 60 percent

. 13 This control is a technically feasible option for the control of SO 2 from SN

- 01

.

13 "Assessment of Control Technology Options for BART

- Eligible Sources: Steam Electric Boilers, Industrial Boilers, Cement Plants and Paper and Pulp Facilities" Northeast States for Coordinated Air Use Management (NESCAUM), March 2005

.

Southwest ern Electric Power Company 5

- 1 Trinity Consultants BART Analysis

– Flint Creek

### 5.2.2 D RY 

### S CRUBB ER

In a d ry scrubb er, an alkaline reagent (usually lime) and water is introduced into the flue gas stream, where it reacts with SO 2 to form calcium sulfite and calcium sulfate. The liquid

- to

- gas ratio is such that the heat from the exhaust gas causes the water to evaporate
before leaving the scrubber outlet. This leads to the formation of a dry powder which is
carried out with the gas and collected with a fabric filter. Existing dry scrubber control efficiencies range from 60 to 95 percent. 14 This is a technically feasible option for the
control of SO 2 from SN

- 01.

There are various designs of dry scrubbing systems. In th e spray dryer absorber (SDA) design, a fine mist of lime slurry is atomized into an absorption vessel where the SO 2 is absorbed by the slurry droplets. The mixture of reaction products (calcium sulfite/sulfate), unreacted lime, and fly ash is carried out with the exhaust gas and collected with a fabric
filter

. Circulating dry scrubbing (CDS) is another type of dry scrubbing. In the CDS process, the flue gas is introduced into the bottom of a reactor vessel at high velocity through a venturi nozzle; the e xhaust is mixed with water, hydrated lime, recycled flyash
and CDS reaction products. The intensive gas

- solid mixing that occurs in the reactor promotes the reaction of SO 2 in the flue gas with the dry lime particles. As with SDA, t he
mixture of reaction products (calcium sulfite/sulfate), unreacted lime, and fly ash is carried
out with the exhaust gas and collected with a fabric filter

. A large portion of the collected particles is recycled to the reactor to sustain the bed and improve lime utilization.

Novel Integrated Deacidification (NID ) technology is a nother particular type of dry
scrub ber . Hydrated lime is added to recirculated dust in the mixer of the NID system. The solids are sprayed with a thin layer of water in the mixer before being transp orted to the reactor. The amount of water added is only a few percent which means that the dust remains dry. Hydrated lime react s with SO 2 in the NID

- reactor and leads to the formation
of calcium sulfite and calcium sulfate. T he flue gas entrained with dry dust material enters the fabric filter where the dust material is captured and clean air is released to atmosphere

. Most of the solid material captured is reused in the system. The system has a high recirculation ratio of the dry dust material

. Disc ussions with vendors have indicated that
an outlet emission rate of 0.06 lb/MMBtu at Flint Creek will be achievable with the NID technology evaluated

. A rate of 0.06 lb/MMBtu represents a 92% control from the
baseline 30

- day average rate of 0.75 lb/MMBtu. The controlled rate was quoted as an
outlet rate rather th an a straight percent control.



### 5.2.3 W ET 

### S CRUBBER

Wet scrubbing involves scrubbing the exhaust gas stream with a slurry comprised of lime or limestone in suspension. The process takes place in a wet scrubbing tower located
downstream of a PM control device such as a fabric filter or an electrostatic precipitator ( ESP )

. The liquid

- to

- gas ratio is such that the exhaust gas is fully saturated with water and

14 EPA Basic Concepts in Environmental Sciences, Module 6: Air Pollutants and Control Techniques http://www.epa.gov/eogapti1/module6/sulfur/control/control.htm Comment [JJ1]: Do we want to add anything to

t he report here reflecting the email responses we’ve provided to ADEQ/EPA?

Southwest ern Electric Power Company 5

- 2 Trinity Consultants BART Analysis

– Flint Creekhas a similar appearance to a cooling tower ex haust

. Similarly to the c hemistry illustrated
above for dry scrubbing , the SO 2 in the gas stream is absorbed by water and reacts with the lime or limestone slurry to form calcium sulfite or calcium sulfate

. Wet lime scrubbing is capable of achieving 80

- 9 5 percent control when used with lower sulfur coals like those
burned at SN

- 01

. 15 This control is a technically feasible option for the control of SO 2 from
SN

- 01.



## 5.3 R ANK OF 

## T ECHNICALLY 

## F EASIBLE 

## SO 2 

## C ONTROL 

## O PTIONS BY 

## E FFECTIVENESS

The third step in the BART analysis is to rank the technically feasible options according to their effectiveness in reducing the visibility affecting pollutants ( VAP ) . Table 5

- 2 provides a ranking of the control levels for the controls listed in the previous section for SN

- 01.

T A BLE 5

- 2

. C ONTROL E FFECTIVENESS OF T ECHNICALLY F EASIBLE S O 2 C ONTROL T ECHNOLOGIES

Control Technology Controlled Emission Rate (lb/MMBtu) Estimated Control Efficiency

Wet Scrubbing 0.04 95% Dry Scrubb ing, e.g., NID 0.06 9 2 %

Dr y Sorbent Injection 0.30 60%



## 5.4 E VALUATION OF 

## I MPACTS FOR 

## F EASIBLE 

## SO 2 

## C ONTROLS

A shown in Table 5

- 2 , w et scrubbing can achieve a 95% reduction in SO 2 while dry scrubbing or NID can achieve a 92 % reduction in SO 2 , and t hese technologies are the most effecti ve technologies at reducing SO 2 . Step four of the BART analysis procedure is the impact analysis. The BART determination guidelines list the four factors to be considered in the impact analysis:

▲ Cost of compliance
▲ Energy impacts
▲ Non

- air quality impacts; and
▲ The remaining useful life of the source

15 Ibid.

Southwest ern Electric Power Company 5

- 3 Trinity Consultants BART Analysis

– Flint CreekAEP is providing Step 4 and Step 5 evaluation s specific to the NID technology as well as WFGD

. Also, AEP is providing a discussion of energy and non

- air quality impacts of wet scrubbing versus the NID technol ogy.



### 5.4.1 C OST OF 

### C OMPLIANCE

Control Costs The capital and operating costs of WFGD and NID used in the cost effectiveness
calculations were estimated based on EPA ’s Air Pollution Control Cost Manual supplemented with vendor and site

- specific information where a vailable

. The capital costs
were annualized over a 30

- year period and then added to the annual operating costs to obtain the total annualized costs. The details of the capital and operating cost estimates are provided in Appendix A of this report.

Ann ual Tons Reduced
The annual tons reduced that were used in the cost effectiveness calculations were determined by subtracting the estimated controlled annual emission rate from the baseline
annual emission rate. The baseline annual emission rate is the av erage rate from 2001

- 2003 , as reported by AEP in their air emission inventories . The controlled annual emission
rates were based on lb/MMBtu levels believed to be achievable f or the control technology multiplied by the baseline heat input in MMBtu/yr to t he boiler. The baseline heat input is
based on the 2001

- 2003 average daily heat input for SN

- 01 as determined from the EPA’s Clean Air Markets Database (CAMD), divided by 24 hours in a day times an estimated 7,752 hours per year, the average number of ope rating hours from 2001

- 2003.

Cost Effectiveness
The cost effectiveness in dollars per ton of SO 2 reduced was determined by dividing the
annualized cost of control by the annual tons reduced. Table 5

- 3 indicates that the cost
effectiveness of the wet scr ubber at an SO 2 rate of 0.04 lb/MMBtu is approximately $ 4

, 9 00 per ton of SO 2 removed. The cost effectiveness in dollars per deciview of visibility is over $ 476 million/dv across the Class I areas, as seen in Table 5

- 4.

By comparison, Table 5

- 3 shows th e cost effectiveness of a NIDS at an SO 2 rate of 0.06
lb/MMBtu is approximately $ 3

, 8 00 per ton of SO 2 removed

. The cost effectiveness in dollars per deciview is approximately $ 3 68 million/dv across the Class I areas, as seen in
Table 5

- 5

. Table 5

- 3 shows that the wet scrubber is approximately $ 3 5

, 000 /ton incrementally more expensive than the dry scrubber.

Southwest ern Electric Power Company 5

- 4 Trinity Consultants BART Analysis

– Flint Creek

### T ABLE 

### 5

- 3

. S UMMARY OF 

### C OST 

### E FFECTIVENESS FOR 

### SN

- 01 SO 2 

### C ONTROLS

Control Technology Baseline
Emission

Rate Controlled
Emission

Level Annual Heat Input Controlled
Emission

Rate SO 2 Reduced Capital Cost Capital Recovery +
Other Indirect
Annual Costs Annual
Fixed O&M Annual
Variable
O&M Total
Annual

Cost Cost
Effectiveness Incremental
Cost (tpy) (lb/MMBtu) (MMBtu/yr) (tpy) (ton/yr) ($) ($/yr) ($/yr) ($/yr) ($/yr) ($/ton) ($/ton)

NIDS 11,641.00 0.06 37,344,783 1,120.34 10,520.66 281,738,024 30,763,370 205,825 9,478,894 40,448,089 3,845

- Wet Scrubber 11,641.00 0.04 37,344,783 746.90 10,894.10 374,427,351 40,884,248 205,825 12,502,590 53,592,663 4,919 35,198



### Southw estern Electric Power Company 5

- 5 Trinity Consultants BART Analysis

– Flint Creek

### T ABLE 

### 5

- 4

. D OLLAR PER 

### D ECIVIEW 

### C OST 

### E FFECTIVENESS FOR 

### SN

- 01 SO 2 

### C ONTROLS OF 

### W E T 

### S CRUBBING

Caney Creek 0.963 0.334 0.629 53,592,663 85,202,962 $
Hercules-Glades 0.657 0.305 0.352 53,592,663 152,251,885 $ Mingo 0.631 0.208 0.423 53,592,663 126,696,604 $ Upper Buffalo 0.965 0.488 0.477 53,592,663 112,353,592 $ $/dv Class I Area Baseline 98th
Percentile ∆dv WFGD Controlled 98th
Percentile ∆dv Improvement in 98th
Percentile ∆dv Total Annual WFGD
Cost



### T ABLE 

### 5

- 5

. D OLLAR PER 

### D ECIVIEW 

### C OST 

### E FFECTIVENESS FOR 

### SN

- 01 SO 2 

### C ONTROLS OF 

### NID S

Caney Creek 0.963 0.348 0.615 40,448,089 65,769,251 $
Hercules-Glades 0.657 0.312 0.345 40,448,089 117,240,838 $ Mingo 0.631 0.217 0.414 40,448,089 97,700,699 $ Upper Buffalo 0.965 0.501 0.464 40,448,089 87,172,606 $ $/dv Class I Area Baseline 98th
Percentile ∆dv NID Controlled 98th Percentile
∆dv Total Annual NID
Cost Improvement in 98th
Percentile ∆dv



### Southw estern Electric Power Company 5

- 6 Trinity Consultants BART Analysis

– Flint Creek

### 5.4.2 E NERGY 

### I MPACTS AND 

### N ON



### - A IR 

### Q UALITY 

### I MPACTS

Wet scrubbing is expected to achieve a slightly higher level of control of SO 2 emissions compared to the propose d NID technology. However, t he negative non

- air quality environmental impacts are greater with wet scrubbing systems

. W et scrubbers require increased water use and generate large volume s of wastewater and solid waste/sludge that
must be treated. This pl aces additional burdens on the wastewater treatment and solid waste management capabilities

. Moreover, i f wet scrubbing produces calcium sulfite sludge, the sludge will be water

- laden, and it must be stabilized be for e landfilling. Wet scrubbing systems h ave increased power requirements and increased reagent usage over dry scrubb ers

. Wet scrubber

- controlled systems also have the potential for increase d particulate and sulfuric acid mist releases. Thus , from an overall environmental perspective, dry scrub bing (i.e., NID technology) is superior to wet scrubbing

.



### 5.4.3 R EMAINING 

### U SEFUL 

### L IFE

The remaining useful life of SN

- 01 does not impact the annualized capital costs because
the useful li fe of the unit is anticipated to be at least as long as the capital cost recovery period, which is 30 years based on EPA cost estimates

.



## 5.5 E VALUATION OF 

## V ISIBILITY 

## I MPACT OF 

## F EASIBLE 

## SO 2 

## C ONTROLS

A final impact analysis was conducted to assess the visibility improvement achieved by comparing the impacts associated with the basel ine emission rates to the impacts associated with the controlled emission rates. Section 4 of this report documents the existing visibility impairment attributable to SN

- 01. In order to assess the visibility improvement associated with the considered con trol options

, the controlled SO 2 emission rate s w ere modeled using CALPUFF.

The SO 2 emission rate associated with the NID for SN

- 01 is detailed as follows:



### HI P * = 379.44 lb/hr Where: P ( controlled emission level ) = 0. 06 lb/MMBtu HI ( hourly heat input) = 6

, 324 MMBtu/hr

Table 5

- 6 summarizes the lb/hr emission rates that were modeled to reflect the addition of NID S as a control at Flint Creek. The SO 2 rate was developed from the controlled rate of 0.06 lb/MMBtu and the boiler heat inp ut of 6

, 324 MMBtu/hr. The SO 4 emission rate was determined assuming the reduction in SO 4 from the baseline case is proportional to the reduction in SO 2 from the baseline case to the controlled case (92%). The NID S will have co

- effects on some of the aci d gases. The control of H 2 SO 4 will result in fewer sulfates. The NO X emission rate was modeled at the baseline rate. The
NID S involves the use of a baghouse. The change from the current ESP to baghouse will result in changes in PM speciation. All othe r rates that changed from the baseline case were determined using the National Parks Services (NPS) speciation spreadsheets for dry bottom boilers burning pulverized coal using only fabric filter for emissions control.

Southwestern Electric Power Company 5

- 7 Trinity Consultants BART Analysis

– Flint CreekTable 5

- 6 also summarizes the emis sion rates that were modeled to reflect the addition of a wet scrubber on SN

- 01, at an outlet emission rate of 0.04 lb/MMBtu. The SO 2 rate was developed by multiplying the controlled level of 0.0 4 lb/MMBtu by the boiler heat input of 6,324 MMBtu/hr

. The NO X emission rates were modeled at the baseline rates. The PM r ates that changed from the baseline case were determined using the NPS speciation spreadsheets for dry bottom boilers burning pulverized coal using only fabric filter for emissions control. T he SO 4 rates were calculated using the same EPRI methodology used for the baseline case.

T ABLE 5

- 6

. S UMMARY OF E MISSION R ATES M ODELED TO R EFLECT SO 2 C ONTROL S

Control Technology SO 2 (lb/hr) SO 4 (lb/hr) NO
x (lb/hr) PM C (lb/hr) PM F (lb/hr) SOA (lb/hr) EC (lb/ hr)
NIDS 379.4 0.004 1,945.0 35.2 33.9 24.4 1.3
Wet Scrubber 253.0 0.11 1,945.0 35.2 33.9 24.4 1.3

Comparisons of the existing visibility impacts and the visibility impacts based on the NID S , including the maximum modeled visibility impact, 98 th percen tile modeled v isibility impact, and the number of days with a modeled visibility impact greater than 0.5 Δdv, for each Class I area are provided in Table 5

- 7

.

Southwestern Electric Power Company 5

- 8 Trinity Consultants BART Analysis

– Flint Creek

### T ABLE 

### 5

- 7

. S UMMARY OF 

### M ODELED 

### I MPACTS FROM 

### SO 2 

### C ONTROL 

### V ISIBILITY 

### I MPACT 

### A NALYSIS FOR 

### SN

- 0 1 (2001

- 2003)

Caney Creek Wilderness Upper Buffalo Wilderness Hercules Glades Wilderness Mingo NWRMaximum Impact(Δdv)98% Impact (Δdv)# Days > 0.5 ΔdvMaximum Impact(Δdv)98% Impact (Δdv)# Days > 0.5 ΔdvMaximum Impact(Δdv)98% Impact (Δdv)# Days > 0.5 ΔdvMaximum Impact(Δdv)98% Impact (Δdv)# Days > 0.5 Δdv

Existing

Emission Rate 1.318 0.963 48 2.426 0.965 63 2.103 0.657 47 1.488 0.631 20

NIDS 0.753 0.348 6 1.474 0.501 13 0.882 0.312 5 0.694 0.217 4

Post Control Improvement 0.565 0.615 42 0.952 0.4 64 50 1.221 0.345 42 0.794 0.414 15

Wet Scrubber 0.746 0.334 5 1.446 0.488 11 0.845 0.305 5 0.677 0.208 4

Post Control Improvement

over NID S 0.007 0.014 1 0.028 0.013 2 0.037 0.007 0 0.017 0.009 0

Note: The visibility improvement shown in the table has been calculated from baseline and controlled impacts that include more decimal places than what is shown in the table. Due to rounding of the baseline and controlled impacts shown in the table, the visibility improvement ca lculated from the baseline and

c ontrolled impacts shown in the table may be slightly different than the visibility improvement reflected in the table.



### Southwestern Electric Power Company 5

- 9 Trinity Consultants BART Analysis

– Flint CreekAs shown in Table 5

- 7

, based on visibility predictions from the CALPUFF modeling system, the operation of a dry scrubber will result in up to a 0. 647 Δdv improvement (98 th percentile basis) (depending on the Class I area) to the existing visibility impairment attributable to SN

- 01. By comparison, wet scrubbing does not add additional visibility i mprovement for SN

- 01 over dry scrubbing

. The reason wet scrubbing, despite the lower SO 2 emission rate, does not produce greater visibility improvement is because it results in other visibility impairing emissions

. 16



## 5.6 P ROPOSED 

## B ART FOR 

## SO 2

SWEPCO is proposing that the SO 2 BART emission rate for SN

- 01 be 0

. 06 lb/MMBtu

, based on the installation and operation of the NID technology

. AEP is proposing to meet this limit calculated as a 30

- day rolling average over each boiler operating day . Compliance will be demonstrated using data from the existing continuou s emissions monitoring systems (CEMS).

The visibility improvement attributable to SN

- 01 through the use of the NIDS ranges from 48

. 1 % to 6 5

. 6 % across the affected Class I area s (98 th percentile basis) . This level of impr ovement is achievable at a cost ef fectiveness of approximately $ 3

, 80 0 per ton of SO 2 removed. By comparison,

wet scrubbing is incrementally more expensive and offers less visibility improvement overall

. In addition, the adverse environmental impacts from the use of wet scrubbing

, includi ng an increase in particulate and sulfuric acid mist emissions as well as increased water and energy usage and wastewater to be treated

, make dry scrubbing a more appealing option.



### 5.6.1 C OMPARATIVE 

### SO 2 

### BART D ETERMINATIONS

The BART emission level proposed for SN

- 01 is among the most stringent BART emission levels approved for any coal

- fired generating unit over the last two years. I n Oklahoma , for similar boilers, EPA determined BART to be 0.06 lb/MMBtu achieved through use of dry scrubbers. 17 I n Nebraska 18 at the Gerald Gentleman Station, BART for SO 2 was also determined to be 0.06 lb/MMBtu achieved through use of dry scrubbers. These similar units provide a good comparison of emission levels achievable through similar control technology. Level s lower th an 0.06 lb/MMBtu have been considered, but rejected based on lack of operating experience on retrofit units, the incremental cost of additional reductions, and the limited incremental visibility improvement associated with those costs. AEP has no data to suggest that lower emission level s are sustainably achievable with the NID technology in a retrofit application, and has not been guaranteed any better performance by equipment vendors. All of these reasons support rejecting any lower emission level for S N

- 01.

Other BART determinations have resulted in higher emission limitations. For example, in Alabama 19 a smaller EGU was allowed an emission limitation of 0.47 lb/MMBtu through use of flue so rb ent injection or comparable technologies. In Arizona 20 , SO 2 B ART was determined to be in the range of

16 Wet scrubbers have less affinity for acid mist than dry scrubbers; thus, sulfate partic les that form from sulfuric acid in the stack will be lower for dry scrubbers than wet scrubbers. AEP’s best understanding of the reason wet scrubbing does not produce greater visibility improvement that drying scrubbing, despite the lower SO 2 rate, is th at the SO 4 rate associated with wet scrubbing is higher. 17 77 Fed. Reg. 16168 (March 22, 2011). 18 77 Fed. Reg. 40150 (July 6, 2012). 19 77 Fed. Reg. 11937 (Feb. 28, 2012). 20 77 Fed. Reg. 42834 (July 20, 2012).

Sout hwestern Electric Power Company 5

- 10 Trinity Consultants BART Analysis

– Flint Creek0.08

– 0.15 lb/MMBtu from existing w et scrubber s. An EGU in Colorado 21 has a proposed BART emission rate of 0.13 lb/MMBtu through use of dry scrubbing. It is interesting to note that a lower emission rate of 0.09 l b/MMBtu was evaluated and determined not reasonable due to the little visibility improvement as compared to the higher costs between scrubbing at these two rates.

In other determinations

, such as Illinois 22 , the control technology was not stated in the B ART determination but the SO 2 rate determined to be BART was in the range of 0.11

– 0.23 lb/MMBtu, dependent upon boiler type and averaging considerations. SO 2 BART in Kansas 23 was achieved through “scrubbing” with an emission limitation of 0.10 lb/MMBtu f or one boiler and through wet scrubbing with an emission limitation of 0.15 lb/MMBtu for another . A n EGU in Montana 24 similar to AEP’s SN

- 01 has a BART emission rate of 0.08 lb/MMBtu.

The proposed SO 2 BART emission rate is equivalent to the most stringe nt rates previously approved by EPA, is consistent with the design specifications for this equipment, and results in significant visibility improvement in the affected Class I areas. The SO 2 emission rate of 0.06 lb/MMBtu should be adopted as BART for SN

- 01.

21 77 Fed. Reg. 18052 (March 26, 2012). 22 77 Fed . Reg. 3966 (Jan. 26, 2012). 23 77 Fed. Reg. 52604 (Aug. 23, 2011). 24 77 Fed. Reg. 23988 (April 20, 2012).

Sout hwestern Electric Power Company 5

- 11 Trinity Consultants BART Analysis

– Flint Creek

## 6. N O X 

## BART E VALUATION



## 6.1 C ROSS



## - S TATE 

## A IR 

## P OLLUTION 

## R ULE 

## ,
C LEAN 

## A IR 

## I NTERSTATE 

## R ULE 

## , AND 

## BART

On June 7 , 2012 EPA published a final rule allowing states participating in the Cross

- State Air Pollution Rule (CSAPR) trading program to use CSAPR to satisfy BAR T. Arkansas is one of the states with units subject to CSAPR that will participate in a NO X trading program during the ozone

season. EPA commented that “ NO X control in the five ozone season

- only states is achieved predominantly by combustion controls .” 25 Due to the nature of combustion controls, plants typically keep combustion controls in place and running year

- round, even if emission limitations are seasonal. Although Arkansas is an ozone season

- only state, combustion controls would run anytime the uni t is in operation. However, on August 21, 2012, the D. C. Circuit Court of Appeal issued a decision vacating CSAPR and ordering EPA to continue to implement the Clean Air Interstate Rule (CAIR) until a new rule is adopted to replace it. The Court’s decis ion will not be effective until the time for filing rehearing petitions has passed, or any filed petitions for rehearing have been considered by the Court. 26 If CSAPR is upheld and implemented in Arkansas, SWEPCO proposes rely on CSAPR to satisfy its regio nal haze obligations at SN

- 01.

Prior to adopting CSAPR, EPA issued a rule confirming that CAIR provides greater reasonable progress toward the national visibility goal than application of BART for NO X emissions at BART

eligible sources. 27 Since EPA has m ade the determination that CAIR reductions provide better progress than BART, and Arkansas has adopted the CAIR requirements into the Arkansas SIP, 28 SWEPCO should be entitled to rely upon CAIR to satisfy its obligations for NO X reductions at SN

01, if CSAP R is vacated in accordance with the D. C. Circuit’s opinion.

In the alternative, SWEPCO has evaluated the cost

- effectiveness and visibility improvement of candidate BART controls at SN

- 01. The visibility improvements associated with the addition of NO X controls at SN

- 01 are minimal, and the cost

- effectiveness values for all control options exceed the values previously determined to be reasonable in EPA’s presumptive BART analysis. However, visibility improvements consistent with the modeled values used in CENRAP’s analysis for the interstate transport portion of Arkansas’s Regional Haze SIP obligations can be achieved with the addition of newer generation LNB/OFA systems, and are proposed as BART for SN

- 01. If ADEQ determines that SWEPCO cannot rely on CAIR or CSAPR as an alternative to BART, the proposed BART emission rate for NO X at SN

- 01 is 0.23 lb/MM Btu calculated as a 30

- day rolling average over each boiler operating day based on the application of LNB/OFA controls.

25 “Regional Haze: Revisions to Provisions Governing Alternatives to Source

- Specific Best Available Retrofit Technology (BART) Determination, Limited SIP Disapprovals, and Federal Implementation Plans,” 77 Fed. Reg. 33651 (June 7, 2012). 26 EME Homer City v. EPA, Case No. 11

- 1302 and consolidated cases, Opinion , (D.C. Cir. Aug. 21, 2012)

. 27 70 Fed. Reg. 39104, 39136

- 37, and 39143 (July 6, 2005). 28 APC&E C Reg. 19.1401 et seq. ; approved at 72 Fed. Reg. 54556 (Sept. 26, 2007).

Southwestern Electric Power Company 6

- 1 Trinity Consultants BART Analysis

– Flint Creek

## 6.2 I DENTIFICATION OF 

## A VAILABLE 

## R ET ROFIT 

## NO X 

## C ONTROL 

## T ECHNOLOGIES

Nitrogen oxides, NO X , are produced during fuel combustion when nitrogen contained in both the fuel and the combustion air is exposed to high temperatures. The origin of the nitrogen (i.e. fuel vs. combustion air) has led to the use of the terms “thermal” NO X and “fuel” NO X when describing NO X emissions. Thermal NO X emissions are produced when elemental nitrogen in the combustion air is exposed to a high temperature zone and oxidized. Fuel NO X emissions are created during the rapid oxidation of nitrogen compounds contained in the fuel.

Nitrogen oxide (NO) is typically the predominant form of NO X from fossil fuel combustion. Nitrogen dioxide (NO 2 ) makes up the remainder of the NO X . The formation of NO X compounds in utility boilers is sensitive to the method of firing. In a wall

- fired boiler, such as SN

- 01, burners are mounted in the boiler walls, producing discrete flames in the furnace. In tangentially

- fired boilers, a single rotating flame is created in the center of the furnace, rather than the discrete flames produced by burners in the wall

- fired boilers. Tangentially fired boilers typically have lower uncontrolled NO X emissions than wall

- fired boilers. Therefore baseline NO X emission rates can vary significantly from plant to plant due to method of firing and also several other factors.

Step 1 of the BART determination is the identification of all available retrofit NO X control technologies. The available retrofit NO X control technologies are summarized in Table 6

- 1 for SN

- 01.

NO X emissions controls, as listed in Table 6

- 1 , can be categorized as combustion or post

- combustion controls. Combustion controls, including flue gas recirculation (FGR ), overfire air (OFA), and Low NO X Burners (LNB), reduce the peak flame temperature and excess air in the furnace which minimizes NO X formation. Post

- combustion controls, such as selective catalytic reduction (SCR) and selective non

- catalytic reduction (SNCR) convert NO X in the flue gas to molecular nitrogen and

water.

T ABL E 6

- 1

. A VAILABLE NO X C ONTROL T ECHNOLOGIES FOR SN

- 01

NO X Control Technologies

Combustion Controls Flue Gas Recirculation (FGR)
Overfire Air (OFA)

Low NO X Burners (LNB)

Post

- Combustion Controls Selective Catalytic Reduction (SCR)

Selective Non

- Cata lytic Reduction (SNCR)



## 6.3 E LIMINATE 

## T ECHNICALLY 

## I NFEASIBLE 

## NO X 

## C ONTROL 

## T ECHNOLOGIES

Step 2 of the BART determination is to eliminate technically infeasible NO X control technologies that were identified in Step 1. Control ranges were developed using a combi nation of literature control ranges and efficiencies. Becaus e many controlled emission levels from literature were higher than the baseline NO X rate at SN

- 01, vendor estimates were also used to assist in developing the expected emission rates from the kno wn relationships between the control options.

Southwestern Electric Power Company 6

- 2 Trinity Consultants BART Analysis

– Flint Creek

### 6.3.1 C OMBUSTION 

### C ONTROLS



### 6.3.1.1 F LUE 

### G AS 

### R ECIRCULATION 

### (FGR)

FGR uses flue gas as an inert material to reduce flame temperatures. In a typical flue gas recirculation system, flue gas is collected from the combustion

c hamber or stack and returned to the burner via a duct and blower. The addition of flue gas reduces the oxygen content of the “combustion air” (air + flue gas) in the burner. The lower oxygen level in the combustion zone reduces flame temperatures; which in turn reduces thermal NO X formation

. When operated without additional controls, the NO X control range for coal fired boilers with FGR is approximately 5

- 25% for coal fired boilers, or 0.23

- 0.29 lb/MMBtu from SN

- 01

. 29 This control is a technically feasib le option for the control of NO X from SN

- 01.



### 6.3.1.2 O VERFIRE 

### A IR 

### (OFA)

OFA diverts a portion of the total combustion air from the burners and injects it through separate air ports above the top level of burners. Staging of the combustion air creates an initial fuel

- rich combustion zone with a lower peak flame temperature. This reduces the formation of thermal NO X by lowering combustion temperature and limiting the availability of oxygen in the combustion zone where NO X is most likely to be formed. OFA as a sin gle NO X control technique results in estimated NO X emissions for coal fired boilers of approximately 10%, or 0.28

- 0

. 29 lb/MMBtu from SN

- 01

. 30 This control is a technically feasible option for the control of NO X from SN

- 01

.



### 6.3.1.3 L OW 

### NO X 

### B URNERS

LNB technology ut ilizes advanced burner design to reduce NO X formation through the restriction of oxygen, lowering of flame temperature, and/or reduced residence time. NO X creation rates typically peak at oxygen levels of five to seven percent. 31 LNB is a staged combustio n process that is designed to split fuel combustion into two zones. In the primary zone, NO X formation is limited by one of two methods. Under staged fuel

- rich condition s , low oxygen levels limit flame temperatures resulting in less NO X formation. The p rimary zone is then followed by a secondary zone in which the incomplete combustion products formed in the primary zone act as reducing agents. Alternatively, under staged fuel

- lean conditions, excess air will reduce flame temperature to reduce NO
x format ion. In the secondary zone, combustion products formed in the primary zone act to lower the local oxygen concentration, resulting in a decrease in NO
x formation.

29 “Controlling Nitrogen Oxides Under the Clean Air Act: A Menu of Options.” Utility Boiler section. July 1994. 30 Ibid. 31 http://www.energysolutionscenter.org/boilerburner/Worksho p/RCTCombustion.htm

. Southwestern Electric Power Company 6

- 3 Trinity Consultants BART Analysis

– Flint CreekThe estimated NO X control range for LNBs on coal boilers is 0.20

- 0.26 lb/MMBtu. 32 When comb ined with OFA, the estimated NO X control range on is 0.18

- 0.24 lb/MMBtu

. 33 LNB systems are technically feasible for the control of NO
x from SN

- 01

.



### 6.3.2 P OST 

### C OM BUSTION 

### C ONTROLS



### 6.3.2.1 S ELECTIVE 

### C ATALYTIC 

### R EDUCTION

SCR refers to the process in which NO X is reduced by a mmonia over a heterogeneous catalyst in the presence of oxygen. The process is termed selective because the ammonia preferentially reacts with NO X rather than oxygen, although the oxygen enhances the reaction and is a necessary component of the process. The overall reactions are:

4NO + 4NH 3 + O 2  4N 2 + 6H 2 O

2NO 2 + 4NH 3 + O 2  3N 2 + 6H 2 O

The SCR process requires a reactor, a catalyst, and an ammonia storage and injection system. The effectiveness of an SCR system is dependent on a variety of factors, including the inlet NO X concentration, the exhaust temperature, the ammonia injection rate, and the type of catalyst. The estimated NO X control for SCR on coal fired boilers is 80

- 90%, and is consistent with vendor estimates of 0.067 lb/MMBtu a t SN

- 01 , resulting in an 80% control efficiency

. 34 Control efficiencies of 80

- 90% depend on the design of the boiler as well as the starting baseline emissions. The vendor was able to provide an estimate of control as an outlet emission level of 0.067 lb/ MMBtu, a low emission level . A 90% percent reduction would result in an outlet emission rate of 0.03 lb/MMBtu and has not been guaranteed by a vendor. This control is a technically feasible option for the control of NO X from SN

- 01.



### 6.3.2.2 S ELECTIVE 

### N ON



### - C ATALYTI C 

### R EDUCTION

In SNCR systems, a reagent is injected into the flue gas in the furnace within an appropriate temperature window. The NO X and reagent (ammonia or urea) react to form nitrogen and water. A typical SNCR system consists of reagent storage, multi

- level reagent

- injection equipment, and associated control instrumentation. The SNCR reagent storage and handling systems are similar to those for SCR systems. However, both ammonia and urea SNCR processes require three to four times as much reagent as S CR systems to achieve similar NO X reductions. The estimated NO X control range for SNCR for coal fired boilers is 0.18

- 0.27 lb/MMBtu. 35 This control is a technically feasible option for the control of NO X from SN

- 01.

32 “Controlling Nitrogen Oxides Under the Clean Air Act: A Menu of Options.” Utility Boiler section. July 1994. 33 Ibid. 34 Ibid. 35 Ibid.

Southwestern Electric Power Company 6

- 4 Trinity Consultants BART Analysis

– Flint Creek

## 6.4 R ANK OF 

## T ECHNICALLY FEASIBLE 

## NO X 

## C ONTRO L 

## O PTIONS BY 

## E FFECTIVENESS

The third step in the BART analysis is to rank the technically feasible options according to effectiveness. Table 6

- 2 provides a ranking of the control levels for the controls listed in the previous section for SN

- 01.

T ABLE 6

- 2

. C ONTROL E FFECTIVENESS OF T ECHNICALLY F EASIBLE NO X C ONTROL T ECHNOLOGIES

Control Technology Estimated Controlled Level for SN

- 01 (lb/MMBtu) 36

SCR 0.067
LNB/OFA + SNCR 0.18

- 0.23 37

LNB / OFA 0.18

- 0.24

S NCR 0.18

- 0.27
FGR 0.23

- 0. 29

LNB 0.20

- 0.26

OFA 0.28

- 0 .29

With the exception of the control level for SCR, the control levels in Table 6

- 2 are presented as ranges. This is due to the fact that the specific level of control that is achievable for SN

- 01 based on the applicatio n of the controls listed in Table 6

- 2 is unknown. Based on several discussions between AEP Flint Creek and the Babcock and Wilcox Company , it is believed that combustion controls such

as LNB in combination with OFA will achieve a NO X level of approxi matel y 0.23 lb/MMBtu for SN

01. EPA established presumptive SO 2 and NO X controls for coal

- fired EGUs in the BART rule. For dry

- bottom wall

- fired EGUs, the presumptive NO X limit is 0.23 lb/MMBtu

. 38 The presumptive BART emission rate was modeled for this sourc e by CENRAP. Although 0.23 lb/MMBtu is the presumptive limit for a unit like SN

- 01, the presumptive limit was not automatically assumed the floor for combustion control on SN

- 01. Rather, experience with similar boilers and vendor discussions have led the selection of this emission level. Current NO X emissions from SN

- 01 are approximately 0.31 lb/MMBtu. Further, it is believed that SCR will achieve a NO X level of approximately 0.067 lb/MMBtu and LNB/OFA + SNCR will achieve a level of 0.2 lb/MMBtu or 10

- 2 0% better control than from LNB/OFA alone

. Vendor estimates for LNB/OFA + SNCR were not available at the time of this analysis, and obtaining vendor estimates would add significantly to the timing of this analysis submittal.



## 6.5 E VALUATION OF 

## I MPACTS FOR 

## F EASIBLE 

## NO X 

## C ONTROLS

Step four for the BART analysis is the impact analysis. The BART determination guidelines list four factors to be considered in the impact analysis:

36 Ibid. 37 “Preferred and Alternative Methods for Estimating Air Emissions from Boilers.” Vol ume II: Chapter 2. January 2001. 38 Ibid.

Southwestern Electric Power Company 6

- 5 Trinity Consultants BART Analysis

– Flint Creek▲ Cost of compliance
▲ Energy impacts
▲ Non

- air quality impacts; and
▲ The remaining useful life of the source



### 6.5.1 C OST OF 

### C OMPLIANCE

The capital costs, operating costs, and cost effectiveness of LNB/OFA, LNB/OFA + SNCR and SCR were estimated for the cost analysis.

Control Costs The capital and operating costs of the controls that were used in th e cost effectiveness calculations were estimated based on vendor estimates and published calculation methods. The EPA Air Pollution Control Cost Manual was followed to the extent possible and was supplemented with vendor and site

- specific information wher e available. The capital
costs were annualized over a 15

- year period for LNB/OFA and over a 20

- year period for both SCR and SNCR, and then added to the annual operating costs to obtain the total annualized costs. The details of the capital and operatin g cost estimates are provided in Appendix B of this report.

Annual Tons Reduced
The annual tons reduced that were used in the cost effectiveness calculations were determined by subtracting the estimated controlled annual emission rate from the baseline
annual emission rate.

The baseline annual emission rate is the average rate as reported by AEP in the 2001

- 2003
air emission inventories. The controlled annual emission rate is based on the lb/MMBtu
level believed to be achievable from the control techn ology multiplied by the baseline heat input to the boiler in MMBtu/yr. The baseline heat input is based on the 2001

- 2003 average daily heat input for SN

- 01 as determined from the EPA’s Clean Air Markets Database (CAMD), divided by 24 hours in a day times a n estimated 7,752 hours per year, the average number of operating hours from 2001

- 2003.

Cost Effectiveness The cost effectiveness in dollars per ton of N O X reduced was determined by dividing the annualized cost of control by the annual tons reduced. An incremental cost analyses was also performed to show the incremental increase in costs between SCR and an LNB/OFA system, as well as between LNB/OFA + SNCR and LNB/OFA. The costs effectiveness analysis is summarized in Table 6

- 3.

In the BART guidelines , EPA calculated that for all types of boilers other than cyclone boilers, combustion control technology is generally more cost

- effective than post

combustion controls. EPA estimates that approximately 75 percent of the BART units (non

- cyclone) could meet the presumptive NO X limits at a cost of $100 to $1,000 per ton of

Southwestern Electric Power Company 6

- 6 Trinity Consultants BART Analysis

– Flint CreekNO X removed based on the use of combustion control technology. 39 For the units that could not meet the presumptive limits using combustion control technology, EPA estimates
that almost all of these sources could meet the presumptive limits using advanced combustion controls. The EPA estimates that the costs of such controls are usually less than $1,500 per ton of NO X removed. 40

Table 6

- 3 indicates that the cost effectiveness of LNB/OFA at a NO X rate o f 0.23
lb/MMBtu is $ 2,579 per ton of NO X removed. Table 6

- 3 also indicates that the costs for
LNB/OFA/SNCR for SN

- 01 is approximately $3, 6 00 /ton of NO X removed and SCR for
SN

- 01 is more than $ 4

, 3 00 per ton of NO X removed. Additionally, the i ncremental cost of the LNB/OFA/SNCR over the LNB/OFA system is greater than $ 5, 2 00 per ton of NO X removed for SN

- 01. The incremental cost of SCR ov er the LNB/OFA system is nearly $ 4

, 8 00 /ton of NO X removed for SN

- 01.

The cost effectiveness in dollars pe r deciview of visibility improvement attributable to the
each NO X control technology was also determined. Additional details on the visibility improvement analysis are provided below. The cost of LNB/OFA is approximately $ 341
million/dv across the Class I areas, as seen in Table 6

- 4. The cost of LNB/OFA plus
SNCR is approximately $ 5 88 million/dv across the Class I areas, as seen in Table 6

- 5.
Table 6

- 6 shows that control of NO X from SCR results in a cost of approximately $ 895
million/dv across the Class I areas. So a review of cost effectiveness on a dollars per deciview basis reveals that both post

- combustion control options are prohibitively expensive relative to the LNB/OFA control option.

39 “Regional Haze Regulations and Guidelines for Best Available Retrofit Technology (BART Determinations; Final Rule.” CFR Vol. 77, No. 128. Wednesday, July 6, 2005, Rules and Regulations. Pages 39134

- 39135. 40 I bid.

Southwestern Electric Power Company 6

- 7 Trinity Consultants BART Analysis

– Flint CreekTABLE 

### 6

- 3

. S UMMARY OF 

### C OST 

### E FFECTIVENESS FOR 

### SN

- 01 NO X 

### C ONTRO LS

Baseline Emission
Rate Controlled
Emission

Level Annual Heat
Input 4 Controlled
Emission

Rate NOx
Reduced Capital Cost Annual Capital Cost Annual
Fixed O&M Annualized
Variable
O&M Total
Annual

Cost Cost
Effectiveness Incremental
Cost (tpy) (lb/MMBtu) (MMBtu/yr) (tpy) (ton/yr) ($) ($/yr) ($/yr) ($/yr) ($/yr) ($/ton) ($/ton)

LNB/OFA 1 5,120.27 0.23 37,344,776 4294.65 825.62 16,000,000 1,756,714 240,000 132,364 2,129,078 2,579

- LNB/OFA/SNCR 2 5,120.27 0.20 37,344,776 3771.82 1348.44 23,124,235 2,429,191 240,000 2,183,048 4,852,239 3,598 5,209

SCR 3 5,120.27 0.07 37,344,776 1251.05 3869.22 121,440,000 11,463,077 1,560,000 3,700,000 16,723,077 4,322 4,795

3 SCR Cost information: Please refer to Appendix B. 1 LNB Cost information: Please refer to Appendix B.

2 SNCR Cost information: Please refer to Appendix B.

4 Baseline heat input was determined from CAMD, 2001-2003, average daily heat inputs times the average number of operating hours from 2001-2003 divided by 24 hours in a day.



### Southwestern Electric Power Company 6

- 8 Trinity Consultants BART Analysis

– Flint CreekTABLE 

### 6

- 4

. D OLLAR PER 

### D ECIVIEW 

### C OST 

### E FFECTIVENESS FOR 

### SN

- 01 NO X 

### C ONTROL 

### U SING 

### LNB/OFA

Caney Creek 0.963 0.849 0.114 2,129,078 18,676,121 $
Hercules-Glades 0.657 0.633 0.024 2,129,078 88,711,577 $ Mingo 0.631 0.617 0.014 2,129,078 152,076,989 $ Upper Buffalo 0.965 0.939 0.026 2,129,078 81,887,609 $ $/dv Baseline 98th
Percentile ∆dv Improvement in 98th
Percentile ∆dv Total Annual
LNB/OFA Cost Class I Area LNB/OFA Controlled 98th
Percentile ∆dv

TABLE 

### 6

- 5

. D OLLAR PER 

### D ECIVIEW 

### C OST 

### E FFECTIVENESS FOR 

### SN

- 01 NO X 

### C ONTROL 

### U SING 

### LNB/OFA P LUS 

### S NCR

Caney Creek 0.963 0.849 0.114 4,852,239 42,563,504 $
Hercules-Glades 0.657 0.623 0.034 4,852,239 142,712,926 $ Mingo 0.631 0.612 0.019 4,852,239 255,381,025 $ Upper Buffalo 0.965 0.932 0.033 4,852,239 147,037,560 $ $/dv Baseline 98th
Percentile ∆dv Improvement in 98th
Percentile ∆dv Total Annual
LNB/OFA + SNCR
Cost Class I Area LNB/OFA/SNCR 98th
Percentile ∆dv

TABLE 

### 6

- 6

. D OLLAR PER 

### D ECIVIEW 

### C OST 

### E FFECTIVENESS FOR 

### SN

- 01 NO X 

### C ONTROL 

### U SING 

### SCR

Caney Creek 0.963 0.718 0.245 16,723,077 68,257,457 $
Hercules-Glades 0.657 0.573 0.084 16,723,077 199,084,249 $ Mingo 0.631 0.588 0.043 16,723,077 388,908,765 $ Upper Buffalo 0.965 0.895 0.07 16,723,077 238,901,099 $ $/dv Baseline 98th
Percentile ∆dv Improvement in 98th
Percentile ∆dv Total Annual SCR
Cost Class I Area SCR Controlled 98th Percentile
∆dv



### Southwestern Electric Power Company 6

- 9 Trinity Consultants BART Analysis

– Flint Creek

### 6.5.2 E NERGY 

### I MPACTS 

### & N ON



### - A IR 

### I MPACTS

SCR systems require electricity to operate the ancillary equipment. The need for electricity to help power some of the ancillary equipment creates a demand for energy that currently
does not exist.

SCR and SNCR can potentially cause significant environmental impacts related to the storage of ammonia. The storage of aqueous ammonia above 10,000 lbs is regulated by a risk management program (RMP), since the accidental release of ammonia has the pote ntial to cause serious injury and death to persons in the vicinity of the release. SCR and SNCR will likely also cause the release of unreacted ammonia to the atmosphere. This is referred to as ammonia slip. Ammonia slip from SCR and SNCR systems occur s either from ammonia injection at temperatures too low for effective reaction with NO
x , leading to an excess of unreacted ammonia, or from over

- injection of reagent leading to uneven distribution; which also leads to an excess of unreacted ammonia. Ammon ia released from SCR and SNCR systems will react with sulfates and nitrates in the atmosphere to form ammonium sulfate and ammonium nitrate. Together, ammonium sulfate and ammonium nitrate are the predominant sources of regional haze.



### 6.5.3 R EMAINING 

### U SEFUL 

### L IFE

The remaining useful life of SN

- 01 does not impact the annualized capital costs of potential controls because the useful life of the boiler is anticipated to be at least as long as the capital cost recovery period, which is 15 years for LNB/OFA and 20 years for SNCR
and SCR

.



## 6.6 E VALUATION OF 

## V ISIBILITY 

## I MPACT OF 

## F EASIBLE 

## NO X 

## C ONTROLS

A final impact analysis was conducted to assess the visibility improvement for existing emission rates when compared to the emission rates associated with LNB/OFA, LNB/OFA/SN CR and SCR systems

. Section 4 of this report documented the existing visibility impairment attributable to SN

- 01. In order to assess the visibility improvement associated with LNB/OFA, SCR and SNCR systems, t he NO X emission rate s associated with both LNB and SCR systems were modeled using CALPUFF. The controlled emission level associated with SCR systems is 0.067 lb/MMBtu for SN

- 01. The controlled emission level associated with the LNB/OFA system is 0.23 lb/MMBtu, and for LNB/OFA/SNCR is 0.21 lb/MMBtu. These levels were multiplied by the maximum heat input to derive hourly the hourly emission rates used in the modeling.

Tables 6

- 7 through 6

- 9 summarize the NO X emission rates that were modeled to reflect the LNB/OFA SCR and LNB/OFA/ SNCR systems, respe ctively. The emission rates for the other pollutants shown in Tables 6

- 7 through 6

- 9 are the same as in the baseline modeling.

Sout hw estern Electric Power Company 6

- 10 Trinity Consultants BART Analysis

– Flint CreekT ABLE 6

- 7

. S UMMARY OF E MISSION R ATES M ODELED TO R EFLECT LNB/OFA FOR NO X C ONTROL

SO 2 (lb/hr) SO 4 (lb/hr) NO X (lb/hr) PM C (l b/hr) PM F (lb/hr) SOA (lb/hr) EC (lb/hr)
4,728.4 3.1 1,454.5 65.1 50.1 15.1 1.9

T ABLE 6

- 8

. S UMMARY OF E MISSION R ATES M ODELED TO R EFLECT SCR FOR NO X C ONTROL

SO 2 (lb/hr) SO 4 (lb/hr) NO X (lb/hr) PM C (lb/hr) PM F (lb/hr) SOA (lb/hr) EC (lb/hr)
4,728.4 3.1 42 3.7 65.1 50.1 15.1 1.9

T ABLE 6

- 9

. S UMMARY OF E MISSION R ATES M ODELED TO R EFLECT LNB/OFA + SNCR FOR NO X C ONTROL

SO 2 (lb/hr) SO 4 (lb/hr) NO X (lb/hr) PM C (lb/hr) PM F (lb/hr) SOA (lb/hr) EC (lb/hr)
4,728.4 3.1 1,277.74 65.1 50.1 15.1 1.9

Table 6

- 10 provide s a comparison of the existing visibility impairment and the visibility impairment associated with the addition of NO X controls on SN

- 01 in all affected Class I areas , including the maximum modeled visibility impact, 98 th percentile modeled visibility impa ct, and the number of days with a modeled visibilit y impact greater than 0.5 Δdv.

Sout hw estern Electric Power Company 6

- 11 Trinity Consultants BART Analysis

– Flint Creek

### T ABLE 

### 6

- 10

. S UMMARY OF 

### V ISIBILITY 

### I MPROVEMENT 

### A SSOCIATED WITH 

### NO X 

### C ONTROL 

### S YSTEM ON 

### SN

- 01 (2001

- 2003)

Caney Creek Wilderness Upper Buffalo Wilderness Hercules Glades Wilderness Mingo NWRMaximum Impact (Δdv)98% Impact (Δdv)# Days > 0.5 ΔdvMaximum Impact (Δdv)98% Impact (Δdv)# Days > 0.5 ΔdvMaximum Impact (Δdv)98% Impact (Δdv)# Days > 0.5 ΔdvMaximum Impact (Δdv)98% Impact (Δdv)# Days > 0.5 Δdv

Exi sting Emission

Rate 1.318 0.963 48 2.426 0.965 63 2.103 0.657 47 1.488 0.631 20

LNB/OFA 1.232 0.849 39 2.130 0.939 56 1.938 0.633 43 1.361 0.617 17

Post Control
Improvement 0.086 0.114 9 0.296 0.026 7 0.165 0.024 4 0.127 0.014 3

SCR 0.986 0.718 22 1.569 0.895 41 1.589 0.573 33 1.099 0.588 14

Improvement

over LNB/OFA 0.246 0.131 17 0.561 0.044 15 0.349 0.06 0 10 0.262 0.029 3

LNB/OFA+ SNCR 1.201 0.849 36 2.022 0.932 54 1.878 0.623 42 1.316 0.612 17

Improvement

over LNB/OFA 0.031 0 .000 3 0.108 0.007 2 0. 06 0.01 0 1 0.045 0.005 0

Note: The visibility improvement shown in the table has been calculated from baseline and controlled impacts that include more deci mal places than what is shown in the table. Due to rounding of the baseline and controlled impacts shown in the table, the visibility improvement calculated from the baseline and controlled impacts shown in the table may be slightly different than the visibility improvement reflected in the table.



### Sout hwestern Electric Power Company 6

- 12 Trinity Consultants BART Analysis

– Flint CreekThe operation of an LNB/OFA system results in an estima ted 0.01 to 0. 11 Δdv imp rovement ( 2 to 12 percent) ( 98 th percentile basis) of visibility impairment attributable to SN

- 01 at the modeled Class I areas. Further, the operation of SCR systems results in an estimated 0.0 2 to 0. 1 3 Δdv incremental improvement over LNB/OFA alone, while LNB/OFA + SNCR results in an estimated 0 to 0.0 1 Δdv incremental i mprovement over LNB/OFA alone.



## 6.7 P ROPOSED 

## B ART FOR 

## NO X
If CSAPR is upheld and implemented in Arkansas, SWEPCO will rely on CSAPR to satisfy its regional haze oblig ations at SN

- 01. If CSAPR is vacated, SWEPCO should be entitled to rely on EPA’s prior determination that CAIR provides greater reductions than BART, and satisfy its obligations by continuing to comply with CAIR.

If a full evaluation of BART is required, the cost

- effectiveness of the control options and the limited incremental improvement in visibility in the affected Class I areas do not justify the installation of SCR or SNCR. SWEPCO proposes a BART emission rate of 0.23 lb/MMBtu calculated as a 30

- day rolling average for each boiler operating day , achievable through use of LNB/OFA. The visibility improvement attributable to SN

- 01 through the use of LNB/OFA ranges from 2. 2 % to 11

. 8 % across the affected Class I area s . This level of improvement is achie vable at a cost effectiveness of approximately $2, 600 per ton of NO X removed. Although LNB/OFA plus SNCR adds a slight visibility improvement over LNB/OFA alone, the small improvement does not justify the incremental cost of over $5

, 20 0 per ton of NO X rem oved. The incremental cost for SCR at SN

- 01 is nearly $ 4

, 800 per ton of NO X removed, and is an excessive cost to be considered BART. In addition, the adverse environmental impacts from the use of SCR, including an increased demand for electricity and the potential for ammonia slip, which could create haze, outweigh the limited, imperceptible improvements in visibility associated with its use at SN

- 01

.

Southwestern Electric Power Company 6

- 1 3 Trinity Consul tants BART Analysis

– Flint Creek

## 7. PM 10 

## BART E VALUATION

EPA’s Approval and Promulgation of Implementation Plans published March 12, 20 12, determined that the currently installed ESP is BART for PM 10 for SN

- 01 . As such, no further PM 10 analysis has been conducted

.

Southwestern Electric Power Company 7

- 1 Trinity Consultants BART Analysis

– Flint Creek

## A PPENDIX 

## A

S O 2 

### C ONTROL 

### C OST 

### C ALCUL A TIONS

Southwestern Electric Power Company Trinity Consultants BART Analysis

– Flint Creek

## A PPENDIX 

## B

NO X 

### C ONTROL 

### C OST 

### C ALCULATIONS

Southwestern Electric Power Company Trinity Consultants BART Analysis

– Flint Creek

## A PPENDIX 

## C

CALMET P ROTOCOL

T he meteorological data used in the analyses presented in this report was originally developed in
2007 and was first used in a BART determination for Oklahoma Gas & Electric. Because the
d evelopment of a set of CALMET/CALPUFF meteorological data is so intensive, this same dataset has been used numerous times since 2007 for various other BART projects in EPA Region 6. The protocol that accompanied the original development has followed the d ataset in each case and is doing so here again.

Southwestern Electric Power Company Trinity Consultants BART Analysis

– Flint Creek