May 11, 2010

Gerardo Rios, Chief

Permits Office

USEPA Region 9

75 Hawthorne Street

San Francisco, CA 94105

Subject: Information to Support Finalization of the Prevention of Significant 

Deterioration (PSD) Permit for Avenal Energy Project (Project)

Dear Mr. Rios:

I am writing on behalf of Avenal Power Center, LLC (APC), to follow up on the 

conference call we had last Thursday with you and your team regarding the PSD permit 

referenced above. I understand from this call there may be a need for more discussions 

regarding the Biological Opinion and modeling related to the new hourly standard for 

NO2; you indicated, however, that the only remaining issues on the permit itself are as 

follows:

1. APC’s requested change from limits on annual number of operation hours for the 

Project duct burners and auxiliary boiler;

2. Best Available Control Technology (BACT) requirements for startups;

3. BACT requirements for carbon monoxide for combustion gas turbine operation 

with and without duct firing;

4. Air dispersion modeling of simultaneous gas turbine and auxiliary boiler 

emissions during startups;

5. Emergency generator engine combustion technology and emission control 

technology; and

6. Emergency fire water pump engine combustion technology and emission control 

technology.

As we discussed last Thursday, this letter should provide all the information you need to 

resolve these issues in the final permit package.

1. APC’s requested change from limits on annual number of operation hours for 

the Project duct burners and auxiliary boiler

In our July 15, 2009 letter transmitting our comments on the draft PSD Permit for the 

Avenal Energy Project, we requested that annual restrictions on usage of the duct burners

and the auxiliary boiler be changed from limits on annual hours to limits on annual heat 

input. The reason for the requested change is that the hour limits provide no additional 

sierra

research

1801 J Street

Sacramento, CA 95811

Tel: (916) 444-6666

Fax: (916) 444-8373

Ann Arbor, MI

Tel: (734) 761-6666

Fax: (734) 761-6755
Gerardo Rios -2- May 11, 2010

environmental protection (as compared with fuel-based limits), yet impose an 

unnecessary constraint on operation of the duct burners and auxiliary boiler. 

As stated in that letter, all annual emission calculations and air quality impact analyses in 

the February 2008 initial application were based on heat input in MMBtu. Therefore, the 

environmental impacts computed in the impact analysis cannot increase beyond those 

described in the initial application,

1 and in the March 2, 2010 request to the San Joaquin 

Valley Air Pollution Control District (District) for modification of the Project’s Final 

Determination of Compliance (FDOC).

2

Specifically, the draft PSD permit annual limit of 800 hours/year for duct firing on each 

HRSG3 should be changed to an annual heat input limit of 899,600 MMBtu/year for 

facility duct burning (562.26 MMBtu/hr [HHV] x 800 hours/duct burner x 2 duct 

burners). Also,the draft PSD permit annual limit of 1,248 hours/year of auxiliary boiler 

operation that appears in Section E on page 8 of draft permit proposed permit conditions 

should be changed to an annual heat input limit of 46,675 MMBtu/year (37.4 MMBtu/hr 

x 1,248 hours). 

2. Best Available Control Technology requirements for startups

EPA has requested a supplemental assessment of BACT requirements during gas turbine 

startups and shutdowns of the gas turbine/HRSG. A top-down BACT analysis was 

submitted to EPA4 on October 15, 2009, that included a detailed discussion of the 

following possible control technologies for startup emissions, by pollutant, as outlined 

below.

For nitrogen oxides (NOx):

• A Selective Catalytic Reduction (SCR) system capable of continuously 

complying with a limit of 2.0 ppmvd @15% O2 (1-hour average);

• A SCONOx system capable of continuously complying with a limit of 

2.0 ppmvd @15% O2 (1-hour average);

• Fast-start technologies (i.e., Rapid Response);

• General Electric OpFlex Startup NOx; and

• Operating practices to minimize the duration of startup and shutdown.

 1 For example, the air dispersion modeling results included the impacts of 46,675 million British thermal 

units per year (MMBtu/yr) of heat input to the auxiliary boiler. 2 For example, the impacts of the requested reduced annual emissions of 198,840 pounds per year of NOx 

would be less than the compliant originally modeled impacts from NOx emissions of 556,317 lbs/year. 3 USEPA. Draft PSD Permit Statement of Basis and Ambient Air Quality Impact Report, Table 7-1, p.17, 

June 2009.

4 Downey Brand. Prevention of Significant Deterioration Permit for the Avenal Energy Project, Client 

Matter No. 39011.00001, October 15, 2009.
Gerardo Rios -3- May 11, 2010

For carbon monoxide (CO) and volatile organic compounds (VOC):

• An oxidation catalyst unit capable of achieving 2 ppmvd @ 15% O2;

• Fast-start technologies (i.e., Rapid Response); and

• Operating practices to minimize the duration of startup and shutdown.

That BACT analysis reached the conclusions outlined below, by pollutant.

NOx: 

BACT for NOx during startups/shutdowns is the use of operating 

systems/practices that reduce the duration of startups and shutdowns to the 

greatest extent feasible, and the use of operational techniques to initiate ammonia 

injection as soon as possible during a startup. Because the duration of each 

startup event is strongly determined by a number of environmental factors (e.g., 

ambient temperature and the length of time the unit has been shut down prior to 

the restart), and because of the lack of operating experience with systems like 

Rapid Response, and the lack of guaranteed emission reductions during startups 

associated with OpFlex, the emission reductions associated with these 

technologies during startups are impossible to quantify; and an individual startup 

may take as long as a traditional startup. Therefore, BACT is determined to be the 

application of operating systems/practices that minimize startup and shutdown 

durations, in combination with the use of operational techniques to initiate 

ammonia injection as soon as possible during a startup.

CO: 

BACT for CO during startups/shutdowns is the use of operating systems/practices 

that reduce the duration of startups and shutdowns to the greatest extent feasible. 

Because the duration of each startup event is strongly determined by a number of 

environmental factors (e.g., ambient temperature),, and because of the lack of 

operating experience with systems like Rapid Response, the emission reductions 

are impossible to quantify; and an individual startup may take as long as a 

traditional startup. Therefore, BACT is determined to be the application of 

operating systems/practices that minimize startup and shutdown durations.

VOC: 

BACT for VOC during startups/shutdowns is the use of operating systems (i.e., 

Rapid Response) and operating practices that reduce the duration of startups and 

shutdowns to the greatest extent feasible. Because the duration of each startup 

event is strongly determined by a number of environmental factors, and because 

of the lack of operating experience with systems like Rapid Response, the 

emission reductions are impossible to quantify; and an individual startup may 

take as long as a traditional startup. . Therefore, BACT is determined to be the 

application of operating systems/practices that minimize startup and shutdown 

durations.
Gerardo Rios -4- May 11, 2010

PM/PM10/PM2.5: 

Because PM and PM10 emissions result from the characteristics of the fuel burned 

and do not rely on any emissions control system, the BACT determinations for 

SO2 and PM10 emissions during normal operations are applicable during startup 

and shutdown as well.

SOx:

Because SO2 emissions result from the characteristics of the fuel burned and do 

not rely on any emissions control system, the BACT determinations for SO2 (and 

PM10) emissions during normal operations are applicable during startup and 

shutdown as well.

Additional evidence that the fast-start technologies currently being marketed do not 

represent BACT can be found in a review of the Final Determination of Compliance for 

the Lodi Energy Center. That project uses the Siemens version of this technology—

marketed as “Flex 30”—to reduce startup times, but the permitted emission limits during 

startups are similar to those proposed for AEP: 160 lbs/hr for NOx (identical to AEP 

limit); 900 lbs/hr for CO (vs 1000 lbs/hr for AEP); 16 lbs/hr for VOC (identical to AEP).5

Consequently, APC believes that BACT for startups and shutdowns continues to be the 

requirements of EPA’s proposed PSD permit for the project. 

3. BACT for combustion gas turbine operation with and without duct firing

The top-down BACT analysis submitted on October 15, 2009, for normal operation and 

startup and shutdown of the combustion gas turbines applies whether the HRSGequipped duct burners are firing or not. The basic equipment controls include DLN 

combustors on the F-class turbines and low-NOx duct burners. The BACT-compliant 

post-control systems of SCR for NOx and an oxidation catalyst for CO are applicable 

with and without duct firing as demonstrated by the permit condition-required emission 

levels of 2 ppmvd @ 15% O2 for both criteria pollutants.

6

Comments on the draft PSD permit suggested that the BACT analysis for two other 

plants should have driven the CO BACT determination for the proposed project to lower 

levels as follows: Kleen Energy Systems in Connecticut (0.9 to 1.7 ppmvd) and CPV 

Warren in Virginia (1.3 and 1.8 ppmvd without duct burning).

Concerning the Virginia permit, the CO limits are actually not more restrictive than those 

proposed for the Avenal Energy Project because (1) the Virginia CO limits are enforced 

on a three-hour average, not the more restrictive one-hour average proposed for Avenal; 

 5 Final Determination of Compliance, Lodi Energy Center (08-AFC-10), San Joaquin Valley Air Pollution 

Control District, January 22, 2010. 6 See Footnote 3 and Condition C1 on page 6 of Proposed Permit Conditions, June 2009.
Gerardo Rios -5- May 11, 2010

(2) the CO limits are enforced on the basis of an initial source test conducted after plant 

startup, at base load; (3) there are no annual source test requirements, only the ability of 

the agency to request a source test in the future; and (4) the CO limits are not enforced 

through any continuous emissions monitoring requirements. CO emissions from the 

Avenal Energy Project would be continuously monitored, and subject to an annual source 

test. Finally, and most important, the Virginia power plant in the cited permit was never 

built; hence, the proposed CO permit limits were never “achieved in practice” as required 

for a valid BACT determination.

Concerning the Connecticut permit, the Kleen Energy Systems, LLC plant is under 

construction, and therefore will not be able to demonstrate that its proposed CO level is 

“achieved in practice” until late 2010/2011.7 Merely the issuance of a permit to construct 

a project does not establish BACT for the source category.

4. Air dispersion modeling of simultaneous gas turbine and auxiliary boiler 

emissions during startups

Although the auxiliary boiler will generally have limited operation in parallel with the 

combustion gas turbines, air dispersion modeling conducted to compute the ground-level 

air quality impact of Project emissions during normal operation and startup periods 

consistently included simultaneous emissions from both turbines, the auxiliary boiler, and 

even, to be conservative, one-hour testing of the natural gas-fueled emergency generator 

engine and Diesel-fueled emergency fire water pump engine.8

5. Emergency generator engine combustion technology and emission control 

technology

The proposed natural gas-fueled emergency generator engine is an 860 brake horsepower 

Caterpillar Model G3512LE.

9

 The proposed engine technology is lean-burn combustion 

equipped with an integrated Miratech SCR/oxidation catalyst post-combustion control 

system that reduces NOx emissions to 1.0 g/bhp-hr and CO to 0.21 g/bhp-hr. 

6. Emergency fire water pump engine combustion technology and emission control 

technology

The proposed Diesel-fueled emergency fire water pump engine is a lean-burn, 

turbocharged, after-cooled Clarke Model JW6H-UF40 engine.

 7 Kleen Energy Systems, LLC. Web page notes “In Construction” and refers questions to Gordon Holk, 

General Manager, Power Plant Management Services, http://kleenenergy.com/.

Reuters. Reported on Fitch Rating’s expectation that the ongoing construction will stay on schedule to 

complete by June 1, 2010, http://www.reuters.com/article/pressRelease/idUS185325+17-Sep2009+BW20090917, September 17, 2009. 8 The quantitative emission rates from all five emitting units during startups were contained in the 

application for the PSD permit in Air Quality Appendix Table 6.2-2.5. 9 The District FDOC mistakenly used the number 3456 (a Diesel engine) for the Caterpillar model in place 

of the correct number G3512LE; however, the FDOC correctly described the engine as natural gas-fired.
Gerardo Rios -6- May 11,2010 

Thank you for the opportunity to provide additional information on the remaining issues 

related to finalizing the June 16, 2009 draft PSD Permit for the Avenal Energy Project. 

We hope that this information is adequate to issue the final permit. Please contact me if 

any other information is needed. 

Sincerely, 

Gary~e~~~ 

cc: Jim Rexroad, Avenal Power Center, LLC 

Jeff Holmstead, Bracewell & Giuliani, LLP