1 

### Medina, Dayana

From: Pettyjohn, Mary <PETTYJOHN@adeq.state.ar.us>

Sent: Tuesday, March 19, 2013 3:32 PM

To: Medina, Dayana

Subject: FW: FW: Region 6 Response on AEP Flint Creek

Attachments: Alstom Proposal SO2 limit.pdf



### Hi Dayana,

Please see below AEP’s response to EPA’s questions/comments.

Mary

From: kpgaus@aep.com [mailto:kpgaus@aep.com]

Sent: Tuesday, March 19, 2013 3:27 PM

To: Pettyjohn, Mary

Cc: Jeremy Jewell (jjewell@trinityconsultants.com); Br ian Bond (tbbond@aep.com); jchendricks@aep.com;

bwmoore@aep.com; jjhenry@aep.com; wemast@aep.com; kjmunson@aep.com; scarney@aep.com; cfhandley@aep.com

Subject: Re: FW: Region 6 Response on AEP Flint Creek

Mary, Thank you for forwarding EPA's respon se. Our response to EPA's questions/c omments are below in blue text. Let

me know if you have questions.

Kris Gaus, QEP

American Electric Power

Air Quality Services

office: 214/777-1113

fax: 214/777-1138

"Pettyjohn, Mary" < PETTYJOHN@adeq.state.ar.us >

03/14/2013 08:48 AM To "Brian Bond ( tbbond@aep.com )" < tbbond@aep.com >, "Kris Gaus

( kpgaus@aep.com )" < kpgaus@aep.com >, "Jeremy Jewell

( jjewell@trinityconsultants.com )" < jjewell@trinityconsultants.com >

cc

Subject FW: Region 6 Response on AEP Flint Creek

Good morning,

Below are EPA’s response to AEP’s comments. Please let me know if you would like a conference call with ADEQ and EPA.

Best wishes,

Mary

From: Medina, Dayana [ mailto:Medina.Dayana@epa.gov ]

Sent: Wednesday, March 13, 2013 10:17 AM

To: Pettyjohn, Mary

Cc: Donaldson, Guy; Feldman, Michael

Subject: Region 6 Response on AEP Flint Creek

Hi Mary,

Thank you for forwarding the email from AEP/SWEPCO last week. Here is Region 6’s response to the comments from AEP/SWEPCO

regarding Flint Creek. Let me know if you would like to discuss.2 SO 2 Control Efficiency

Thank you for the explanation that in the testimony before the Arkansas PSC, AEP/SWEPCO was basing its discussion of removal

efficiency on the unit’s allowable SO 2 emission rate of 1.2 lb/MMBtu and not necessarily on actual historical emissions. We still

believe, however, that the BART analysis should have additional discussion of the potential performance of the proposed NID

technology. As AEP/SWEPCO pointed out in their response, in the Oklahoma FIP we found it appropriate to select 0.06 lb/MMBtu for

SO 2 BART using dry scrubbers. With NID, which can achieve a higher removal rate than dry scrubbers, one might expect to see a

controlled emission rate below 0.06 lb/MMBtu. ADEQ should ensure that the controlled emission rates evaluated in the BART

analysis reflect what NID is capable of achieving and is not based on analysis of conventional dry scrubbers.

Although different in design configuration, the NID system is a type of dry scrubber, not a different type of technology. Some

advantage is expected from the NID system, however, due to the different method of contact between the flue gas and the reagent

to remove the SO2. The contract with the equipment vendor specifies a SO2 emission rate of 0.055 lb/MMBtu for the NID

system. The proposed rate of 0.06 lb/MMBtu is 92% less than the baseline 30

‐ day average rate of 0.75 lb/MMBtu and represents a

significant reduction in SO2 emissions. As a practical matter, the facility will have to consistently operate below any limit that is

established and some buffer is needed to allow for variability in fuel sulfur content and system operation. Applying a rate limit

below 0.06 lb/MMBtu would provide little or no discernible additional visibility improvement and would impose unnecessary risk for

the facility to be able to maintain compliance with the limit. AEP/SWEPCO believes that the SO2 rate of 0.06 lb/MMBtu is

appropriate for the NID technology and satisfies BART for this facility.

Here is the performance guarantee from the NID vendor.

NOx BART

The only explanation offered in the BART analysis for the selection of 0.23 lb/MMBtu using LNB/OFA is that discussions with the

vendor and experience with similar boilers have led to the selection of this emission level. Please provide documentation from the

vendor and any other available documentation to support the selection of 0.23 lb/MMBtu. While we recognize that the control

efficiency of LNB/OFA can depend on factors specific to the boiler, we note that we approved in the Oklahoma SIP emission limits of

0.15 lb/MMBtu on all 6 coal

‐ fired subject

‐ to

‐ BART units in the state.

It is important to note that all 6 of the coal

‐ fired units referenced in the Oklahoma SIP are tangentially

‐ fired boilers. The Flint Creek

boiler is wall

‐ fired. EPA conducted an evaluation and determined presumptive limits for various technologies to provide guidance

for states in what reductions and technologies may be expected in BART determinations. EPA specifically noted that for most

boilers, "Current combustion control technology is generally, but not always, more cost

‐ effective than post combustion

controls...". They further distinguished between tangentially

‐ fired and wall

‐ fired boilers and provided presumptive NOx limits of

0.15 lb/MMBtu and 0.23 lb/MMBtu respectively. EPA notes that these values may not be appropriate for all sources. AEP/SWEPCO

agrees with the NOx evaluation that EPA conducted for this type of boiler in developing their presumptive limit guidance. Also, the

0.23 lb/mmBtu NOx rate was used for CENRAP modeling other states depend on for their compliance planning. AEP/SWEPCO

believes that LNB/OFA is BART for this type of boiler and that 0.23 lb/MMBtu is the appropriate rate for this facility.

(EPA references are from the Federal Register / Vol 70, No. 128 / Wednesday, July 6, 2005 / Rules and Regulations

‐ Pages 39134 and

39135)

Thank you,

Dayana Medina

U.S. Environmental Protection Agency, Region 6

Multimedia Planning and Permitting Division

Air Planning Section (6PD

‐ L)

214

‐ 665

‐ 7241

medina.dayana@epa.gov