December 8, 2011 

Mr. Gerardo Rios 

Chief, Permits Office 

U.S. EPA, Region 9 

75 Hawthorne Street 

San Francisco, CA 94105 

Subject: Pio Pico Energy Center PSD Permit Application 

 PM BACT for Simple-Cycle Turbines 

 

 

Dear Mr. Rios: 

As requested by EPA in a telephone conversation between Roger Kohn (EPA) and Steve 

Hill (Sierra Research) on November 29, 2011, we are submitting clarifying information 

on behalf of Pio Pico Energy Center, LLC (Applicant). EPA requested additional 

analysis to support the determination in the repackaged PSD application of BACT for PM 

emissions from the simple-cycle turbines. 

Summary of BACT Analysis Contained in the September 15th PSD Package 

On September 15, 2011, the Applicant submitted a repackaged PSD application. The 

top-down PM BACT analysis demonstrated that PM/PM10/PM2.5 BACT for normal 

operation of the simple-cycle gas turbines is the use of natural gas as the primary fuel 

source. The Applicant proposed an emission limit of 5.5 lb/hr, based on vendor 

guarantees and the experience of the Applicant and others with similar installations. 

EPA staff also requested confirmation of the sulfur levels used by the Applicant in its 

emission calculations. The Applicant based its emission calculations on fuel sulfur levels 

of 0.25 gr/100 scf (annual average) and 0.75 gr/100 scf (hourly average).1

Control Level 

EPA has not indicated that it disagrees with the Applicant’s demonstration that BACT for 

this project is the use of natural gas as the primary fuel source; but did request additional 

justification for the proposed compliance limit of 5.5 lb/hr. Additionally, EPA has 

indicated that the compliance limit should be expressed as an emission rate in units of 

lb/MMbtu (HHV) of heat input. 

 

1

 See repackaged PSD Application (September 2011), pp. PSD-4.34, PSD-4.55, and PSD-App-1.53. 

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, EPA -2- December 8, 2011 

Comment: In order to facilitate comparison with other projects, EPA requests that the 

proposed limit be expressed as an emission rate (in units of lb/MMBtu). 

Response: The Applicant’s originally proposed compliance limit of 5.5 lb/hr was 

intended to apply under all circumstances, including full load, low load, startup, and 

shutdown. Because fuel use is different under these conditions, the lb/MMBtu rate will 

be different as well. 

Compliance with the PM limits is demonstrated through the use of periodic source tests. 

As specified in 40 CFR 60.8(a)(4)(c), performance tests are conducted “under such 

conditions as the Administrator shall specify based on representative performance of the 

affected facility.” The Applicant is willing to accept the emission limit of 0.0065 

lb/MMBtu (HHV), which is equivalent to the Applicant’s proposed limit of 5.5 lb/hr, 

when the turbine is operated at or near full load.2

 Compliance with this limit would be 

demonstrated by a source test that complies with all of the requirements set forth in 

40 CFR § 60.8 and 40 CFR Part 60 Appendix A, conducted at or near full load.3

 

Comment: Please provide additional justification for the proposed limit. Compare with 

the limits achieved in practice by other gas turbines. Following the top-down BACT 

procedure, rank the examples from lowest to highest and either explain why they do not 

apply to the project, or revise your proposed BACT emission rate to reflect achieved-inpractice limits. 

Response: Particulate emissions from combustion of natural gas are usually below the 

limits of detection of current EPA test methods. As a result, PM test results from gasfired combustion equipment are highly variable, and are often dominated by testing 

artifacts. Differences in PM emission rates proposed for PSD permits are often 

attributable to the risk tolerance of the applicant and/or equipment vendor, rather than to 

any technical specification. Nonetheless, we have reviewed additional PM BACT 

determinations as requested by EPA. 

The sources listed in the attached Table 1 were considered for this analysis. Information 

in this table was taken from EPA’s fact sheet for the Palmdale Hybrid PSD Permit. 

The most recently permitted units with total PM limits expressed as lb/MMBtu are 

Palmdale Hybrid in California (Palmdale), Warren County Power Station in Virginia 

(Warren County), and Chouteau Power Plant in Oklahoma (Chouteau). Of these three 

facilities, only the Chouteau unit is operational. Because neither Palmdale nor Warren 

County has any operating history, the permit limits are not relevant to an analysis of 

achieved-in-practice emission rates. Therefore, all of the sources listed in Table 1, except 

Chouteau, were eliminated from further consideration. 

 

2

 0.0065 lb/MMBtu = (5.5 lb/hr) / (851.5MMBtu). The heat rate is the lowest peak fuel use rate from the 

design cases. 

3

 EPA Methods 5 and 202, or Methods 201A and 202, for PM, PM10, and PM2.5, or CTM-039 in lieu of 

Method 202. 
Gerardo Rios, EPA -3- December 8, 2011 

The new turbines at Chouteau are subject to a PM limit of 0.0035 lb/MMBtu, averaged 

over 24 hours.4

 Because the source test methodology used to demonstrate compliance is 

comprised of three test runs that can be as short as one hour each, it is impossible to 

determine compliance with a 24-hour average limit for PM expressed as lb/MMbtu. 

PM source tests were conducted at Chouteau on May 18-25, 2011, and again on July 6-8, 

2011.5 The results from initial compliance testing of total PM at Chouteau are 

summarized in Table 2 (attached). Table 2 shows that Chouteau did not comply with its 

PM limits; therefore, this unit does not demonstrate achieved-in-practice BACT. 

As shown in the following table, a statistical analysis of the Chouteau test results 

indicates a mean PM value of 0.0052 lbs/MMbtu, with a relative standard deviation of 

30%. Since permit limits must be met on an on-going basis for the life of the plant, an 

analysis of source test data must include an allowance for variability. The mean plus two 

standard deviations, based on the Chouteau test data, is 0.0084 lbs/MMbtu; thus, if these 

are used to establish a permit limit, the limit should be no lower than 0.0084 lbs/MMbtu. 

Date 5/25/2011

5/22‐

23/2011 5/18/2011

7/7‐

8/2011 7/7/2011 7/6/2011 7/6/2011 7/7/2011

Unit 21 22 22 21 21 21 22 33

Unit Load 100% 100% 60% 60% 100% 100% 100% 100%

DB Load 0% 0% 0% 0% 70% 100% 70% 100%

Run 1 0.0036 0.0042 0.0056 0.0054 0.0058 0.0078 0.0082 0.0069

Run 2 0.0029 0.0035 0.0043 0.0055 0.0061 0.0079 0.0080 0.0039

Run 3 0.0035 0.0040 0.0048 0.0043 0.0047 0.0048 0.0061 0.0039

Average 0.0033 0.0039 0.0049 0.0051 0.0055 0.0068 0.0074 0.0049

Overall Average 0.0052

Overall Std Deviation 0.0016

Relative Std Deviation 30%

Mean plus 2 S.D 0.0084

Summary of Chouteau PM Test Results (lbs/MMbtu)

The PM control level proposed by the Applicant, 0.0065 lb/MMBtu at peak turbine load, 

was based on source test data from similar units operating in Southern California, and is 

the lowest emission rate that assures continuous compliance. It is lower than the level for 

which the turbine vendor will provide guarantees, and it is lower than the value suggested 

by the Chouteau data. 

The Applicant’s proposed limit of 0.0065 lbs/MMbtu is not applicable to low load 

operation, startup, or shutdown. We understand that EPA wishes to consider including in 

the permit an emission rate limit that is applicable to low load operations. We believe 

there is insufficient data upon which to establish a low-load emission rate (in units of 

 

4

 Oklahoma DEQ Permit No. 2007-115-C (M-1) PSD, Condition 1, limits PM10 emissions from Turbines 

EU 1-03 and 1-04 to 6.24 lb/hr (3-hour average, without duct firing), 6.59 lb/hr (3-hour average, with duct 

firing) and 0.0035 lb/MMBtu (24-hour average).

5

 Letter, dated August 19, 2011 from Tadd Henry (Associated Electric Cooperative) to Kendal Stegman 

(Oklahoma DEQ). 
Gerardo Rios, EPA -4- December 8, 2011 

lbs/hr) different from that applicable at maximum load. Because the hourly emissions are 

expected to be about the same for the Pio Pico Energy Center turbines (5.5 lb/hr) at all 

loads, the highest emission rate (in lbs/MMbtu) will occur at the lowest fuel usage, or low 

load. While each turbine will normally operate at close to full load when it is operating, 

each turbine is expected to operate at loads as low as 50% on occasion. The expected 

emission rate at low load is 0.01 lb/MMBtu.6

If you have any questions regarding this information, please contact the Applicant’s 

representative David Jenkins at (317) 431-1004, or Gary Rubenstein or me at 

(916) 444-6666. 

Sincerely, 

Steve Hill 

cc: John McKinsey, Stoel Rives LLP 

David Jenkins, Apex Power Group 

 Steve Moore, SDAPCD 

 

6

 0.01 lb/MMBtu = (5.5 lb/hr) / (542.5MMBtu). This heat input rate is the lowest low load fuel use rate 

from the design cases.
Table 1 

Summary of Recent PM BACT Limits for Combined-Cycle, Natural Gas-Fired Combustion T

Facility Location 

PM Limit 

Without Duct 

Firing 

Type of PM 

Filterable (F) 

Total (T) 

Averaging 

period Control Permit Issuance Source 

Pio Pico Energy Center California 5.5 lb/hr, 

0.0065 lb/MMBtu 

TPM10, TPM2.5 

3-hour Natural Gas Fuel This Application PSD Permit Ap

Avenal Energy Project California 8.91 lb/hr TPM10 12-month 

rolling 

Natural Gas Fuel June 2011 PSD Permit 

Warren County Power Station 

Virginia 0.0027 

lb/MMBtu 

TPM10, TPM2.5 3-hour -- December 2010 PSD Permit 

Carty Plant Oregon 2.5 lb/MMscf FPM10 -- Clean Fuel Draft December 2010 RBLC #OR-004Langley Gulch Power Plant 

Idaho No limit FPM10 -- GCP Draft December 2010 RBLC # ID-001

Colusa Generating Station 

California 13.5 lb/hour TPM, TPM10 12-month 

rolling 

Natural Gas Fuel March 2010 PSD Permit 

Victorville II Hybrid Power Project 

California 12.0 lb/hr TPM, TPM2.5 12-month 

rolling 

Natural Gas Fuel March 2010 PSD Permit 

Chouteau Power Plant Oklahoma 0.0035 

lb/MMBtu 

TPM10 3-hour Natural Gas Fuel January 2009 RBLC # OK-01

Cane Island Power Park Florida 2 gr S/100 SCF TPM10 -- Fuel Spec September 2008 RBLC # FL-030FPL West County Energy Center Unit 3 

Florida 2 gr S/100 SCF PM, 

PM19/PM2.5 

 Clean Fuel July 2008 RBLC # LA-013

Plaquemine Cogeneration Facility 

Louisiana 0.02 lb/MMBtu FPM10,TPM -- Clean Fuel July 2008 RBLC #LA-013

Arsenal Hill Power Plant Louisiana 24.23 lb/hr FPM -- Pipeline Natural 

Gas 

 March 2008 RBLC # LA-022

Kleen Energy Systems Connecticut 11 lb/hr FPM10 -- -- February 2008 RBLC # CT-015Palmdale Hybrid California 0.0048 

lb/MMBtu 

TPM 9-hour Better-than-PUC 

quality natural gas 

October 2011 PSD Permit 
Table 2 

2011 Chouteau Source Test Results 

Date Unit 

CT 

Load 

(%) 

DB 

Load 

(%)

Particulate Emissions

(lb/hr)a 

Permit 

Limit 

(lb/hr) 

Particulate Emissions 

(lb/MMbtu)a 

May 25 21 100 0 

6.01 4.70 5.56

6.24 

0.0036 0.0029 0.0035 

5.42 0.0033 

May 18 22 60 0 

6.97 5.41 6.15

6.24 

0.0056 0.0043 0.0048 

6.18 0.0049 

May 22-23 22 100 0 

7.09 5.68 6.52

6.24 

0.0042 0.0035 0.0040 

6.43 0.0039 

July 7-8 21 60 0 

6.68 6.63 5.33

6.24 

0.0054 0.0055 0.0043 

6.21 0.0051 

July 7 21 100 70 

10.4 11.1 8.58

6.59 

0.0058 0.0061 0.0047 

10.0 0.0055 

July 6 21 100 100

14.6 14.9 8.53

6.59 

0.0078 0.0079 0.0048 

12.7 0.0068 

July 6 22 100 70 

14.8 14.2 10.9

6.59 

0.0082 0.0080 0.0061 

13.3 0.0074 

July 7 22 100 100

12.8 7.35 7.23

6.59 

0.0069 0.0039 0.0039 

9.13 0.0049 

a Individual test run results shown in top row; three-run average shown in bold in bottom row. 

Three-run averages highlighted in yellow exceed applicable limit.