September 10

, 2013

The Honorable Gina McCarthy Administrator, EPA Office of the Administrator U.S. Environmental Protection Agency Room 3000 Ariel Rios Building 1200 Pennsylvania Ave., NW Washington, DC 20460

Melanie King Energy Strategies Group Sector Policies and Programs Division (D243

- 01) U.S. Environmental Protection Agency Research Triangle Park, NC 27711

Lorie Schmidt Associate General Counsel, Air and Radiation Law Office Office of General Counsel Mail Code: 2344A U.S. Environmental Protection Agency 1200 Pennsylvania Ave., NW Washington, DC 20460

RE: Petition for Reconsideration

– National Emission Standards for Hazardous Air Pollutants for Reciprocating Internal Combustion Engines; New Source Performance Standards for Stationary Internal Combustion Engines, 78 Fed. Reg. 6674 (Jan. 30, 2013)

Dear Administrator McCarthy

,

ICAC petitions the Environmental Protection Agency (EPA) for reconsideration of its January 30, 2013 final rule amending the National Emission Standards for Hazardous Air Pollutants (NESHAP) for Reciprocating Internal Combustion Engines (RICE). T he Institute for Clean Air Companies (ICAC) submitted comments on August 9, 2012. As explained below, the purpose of this petition is to address issues of central relevance to the outcome of the final rule, and to strengthen monitoring provisions to allow direct measurement of the primary hazardous air pollutant (HAP)

– formaldehyde

– that is the central focus of the final rule.2

I. Summary

This petition contends that incorrect claims and conclusions submitted to the EPA in a previously submitted Petition for Reconsideration dated, October 18, 2010, by Dresser

- Waukesha, and incorporated by EPA in the final rule, resulted in a final rule that does not adequately or accurately measure HAP from Four Stroke Spark Ignition Lean Burn (4SLBSI) or Four Stroke Rich Burn Spark Ignition Engines (4SRBSI). The final RICE NESHAP rule, signed on January 14, 2013, allows owners of 4

- stroke rich burn spark ignition engines to use non

- reference EPA
methods and non

- correlated surrogate compounds for HAPs to demonstrate compliance with HAP surrogate emissions levels of formaldehyde. The se surrogate compounds and non

reference EPA methods do not properly measure HAP from either 4SLBSI or 4SRBSI engines

.

II. Petition Request

ICAC requests that the EPA reconsider the following:

1. The use of THC or CO surrogate for HAP/formaldehyde for both SI 4SLB and SI 4SRB engines because the Dresser

- Waukesha p etition requesting this option was based on incorrect assumptions of formaldehyde reference method cost and no supporting data in
the doc ket.
2. The use of THC or CO surrogate for HAP/formaldehyde for both SI 4SLB and SI 4SRB engines because there is no correlation between formaldehyde and THC or CO from these engines, and EPA did not adequately address the comments submitted by ICAC

. 3

. Th e exclusion of EPA Method 320 and ASTM D6348 from the recommended test methods for each engine type and class.

III. Background

On January 14, 2013, EPA signed final amendments to the 2010 RICE NESHAP that reflect new technical information submitted by stakeh olders after the 2010 standards were issued. EPA considered a previously submitted Petition for Reconsideration dated, October 18, 2010 by the engine manufacturer Dresser

- Waukesha for reconsideration of the formaldehyde testing requirements on 4 stroke rich burn spark ignition engines (4SRBSI)

. In the petition for reconsideration, Dresser

- Waukesha argued that formaldehyde is difficult and costly to measure.
The Dresser

- Waukesha petition requested that the HAP surrogate for 4SRB engines should be
THC or CO rather than formaldehyde. Dresser

- Waukesha submitted data from testing that does not support that THC reduction across the catalyst is an appropriate surrogate for HAP reduction across the catalyst ; nevertheless, the data was used as the justification to use other surrogates for formaldehyde, THC or CO, as a surrogate for HAPs. EPA granted the petition for reconsideration on January 5, 2011.3

FTIR Test Costs Are Not Expensive

The contention in the Dresser

- Waukesha petition was that the cost of testi ng for HAP with the EPA and industry accepted surrogate compound, formaldehyde, with the EPA reference method for formaldehyde, EPA TEST METHOD 320 ( Measurement of Vapor Phase Organic and Inorganic Emissions by Extractive Fourier Transform Infrared (FTIR) Spectroscopy )

, or the accepted alternative method

, ASTM D6348

– 12 ( Standard Test Method for Determination of Gaseous Compounds by Extractive Direct Interface Fourier Transform Infrared (FTIR) Spectroscopy ) was “too costly and complex,” and that alternative test methods exist that would

“ provide a less expensive and less complex, but equally effective, method for demonstrating compliance than testing for formaldehyde.”

The Dresser

- Waukesha petition also contend ed that other gases are “easier to measure”, or “much less expensive to measure.” No data were cited, listed, tabulated, or brought forward to demonstrate that these “other gas” measurements or alternative test methods are less expensive or easier to perfor m. In fact, 25 companies ( see A ppendi x A) are performing formaldehyde measurements daily with FTIR technology at near or below the cost of the unsupported surrogate test for carbon monoxide (CO) monitoring. Moreover, t he third party compliance

- testing pr ice in some cases is significantly below the cost o f the inlet and outlet CO testing that is required to show reduction efficiency.

Many of the companies listed in Appendix A have confidentially agreed to submit their costs for a complete RICE

- MACT comp liance test for formaldehyde using one of the EPA reference methods for formaldehyde (the accepted HAP surrogate for 4SRB and 4SLB engines), including other HAP monitoring . I n many cases, the cost range is only $1,400 to $3,500 (see Appendix B )

. The fina l rule also added an exemption from testing for engines that are outside an arbitrary
quarter

- mile distance due to the costs and difficulty of testing companies to make it to these
“rural” locations. The emission

- testing companies listed below offer the s ame prices for RICE

MACT engine tests, no matter their location.

The Surrogacy Issue

A lternative testing that does not scientifically act as a surrogate for formaldehyde or HAPs is now going to be accepted as a surrogate for HAPs emissions

. The EPA reference method for formaldehyde is self

- validating, has a high degree of QA/QC performed, and is legally
defensible in a court of law. The surrogate testing requested, THC or CO, in the Dresser

Waukesha p etition does not correlate with formaldeh yde surrogate HAP testing

. The data submitted on surrogate compounds for formaldehyde were flawed in its statistics and
conclusions.4

The ICAC submitted its specific comments to these issues on August 9, 2012

. ICAC’s

comments clearly pointed out the problems with the surrogate methods for measuring formaldehyde accurately, the lack of correlation in the data submitted in the Dresser

- Waukesha

p etition

, and championed the accuracy, excellent QA/QC requirements, and the lack of

c omplexity in the EPA reference method for formaldehyde. Additional data from 53 field compliance source tests was submitted with the ICAC comments letter to refute the data and
conclusions in the Dresser

- Waukesha p etition

. EPA has received sufficient dat a to demonstrate that no correlation between formaldehyde and THC or CO exists. In Appendix C

, data are again presented that demonstrate why CO should not be and is not a surrogate for HAP or formaldehyde for any type of RICE

- MACT engine.

ICAC ’s comments explained why there is limited to no correlation. Formaldehyde present in the emission exhaust from these engines is not generated during the primary combustion, but during the exhaust transport, i.e.; formaldehyde is not generated when CO is generated du ring the primary combustion. Therefore, there can be no correlation that is statistically based on CO. In a SI 4SLB engine exhaust, significant formaldehyde emissions are possible and probable even when there is little to no CO or VOC emission, because formaldehyde is generated by the partial
oxidation of the CH 4 slip through the exhaust train at temperatures between 750°F and 1,000°F

. The main contributing factors to the formaldehyde emission are CH 4 slip, O 2 concentration, linear flow rates, exhaust t emperatures, and catalyst age, and are not correlated to CO or VOC
emissions. These findings are appended below, and can be duplicated in any catalyst

- research laboratory throughout the country.

An additional assertion made in the Dresser

- Waukesha p etiti on was that CO is allowed for other engine types, specifically SI 4SLB engines, as a surrogate for HAP and/or formaldehyde based on a limited study performed at Colorado State University, so they should be allowed for SI 4SRB as well. In that study, the c orrelations were questionable at best, and the testing was performed under very tightly controlled conditions, which clearly do not exist in the field during actual natural gas compression. ICAC ’s comments presented real engine

- exhaust test data (collecte d during compliance tests) on a cross section of RICE

- MACT engines both SI 4SLB and SI 4SRB that demonstrated there is limited to no correlation between VOC:CO:formaldehyde for either engine type.

Portable Hand

- Held CO Measurements Do Not Follow EPA R eference T est methods

The final rule also allows a hand

- held portable electro

- chemical cell device to be used to

measure CO . This is not an EPA reference method, has minimal QA/QC due to numerous interferences

, and may only be used for a period of 2 min utes of testing. If a portable is used, then the instrument must be an ETV certified instrument and all testing must meet USEPA’s

CTM

- 034. It is well known by anyone who performs these tests routinely in the field, that these5

engines may vary in their CO emissions concentrations by thousands of parts per million by volume (ppmv) during an hour period and this assertion is supported by the data submitted in
ICAC ’s comments

.

Normal EPA reference test methods require a minimum of three, one

- hour test peri ods as described in the EPA Test Methods 25A, 10, and 320, published in 40CFR Part 60. By allowing
the substitution of EPA Reference Test Method 320 or ASTM Test Method D6348

- 12 for formaldehyde, to demonstrate compliance, with a surrogate test by EPA Test Method 10, instrumental method for CO, that is a surrogate for an EPA Test Method 25A instrumental THC test, with a non

- reference test method using a hand held not validated, non

- reference method for CO for a two minute period, there now exists an option for a “compliance test” that contains no scientifically proven representative test as measured by an EPA Reference Method to prove HAPs emissions from these affected engines covered in the final rule. This is an unprecedented move away from the EPA referen ce test methods to demonstrate compliance with a NESHAP
emissions rule

.

Finally, i n the final rule, EPA has neglected their own reference method for monitoring gas emissions, specifically EPA Method 320 (and with extension ASTM D6348) by not explicitly stating them as valid methods for all RICE

- MACT engine testing. These methods are fully self

validating methods that allow for the accurate measurement of many compounds simultaneously

, including CO, CO 2 , NOx, N 2 O, NH 3 , H 2 O, formaldehyde, and VOC. They a re also the only methods that provide an avenue for post

- data validation that allow for confirmation of the test data. Many of the companies listed below not only perform the RICE

- MACT compliance testing using this technology at costs less than the more t raditional methods, they also have 3 rd parties validate the data at no additional cost to the client or the regulatory agency.

IV. Specific Arguments

There were several inaccuracies in the Dresser

- Waukesha petition , and in the EPA’s ultimate
decision to accept them in the final rule

. The following points show why CO should not be allowed as surrogate for HAP in any RICE

- MACT engine, lean or rich burn.

1. There was no evidence presented by Dresser or any other organization in the docket that
demonstrated f

ormaldehyde was difficult to measure as a surrogate for HAP. There are numerous emission testing companies in the US, today, providing this service as a turn

key analytical service, with the capability of full data validation to pass the EPA
Reference Met hod 320 or EPA accepted ASTM D6348

- 03 reference methods for formaldehyde (See Appendix A ). Additionally, there is an EPA promulgated self

-6

validating method (U.S. EPA Method 320 and 318) and an ASTM method (ASTM
D6348

- 03) for measuring formaldehyde and oth er HAPs.

2. The Dresser

- Waukesha petition argued that formaldehyde is costly to measure. There is no credible data to back up th is claim . The emissions testing companies listed in Appendix B quote an average price of a RICE

- MACT compliance test from ASTM
Method D6348

- 03 measuring for CO / NOx / VOCs / H 2 O and Formaldehyde is in the $2,000 to $3,500 range and as low as $1,400

. This price is far from an onerous burden on the oil and gas industry and no where near twice as much as mentioned in the Dresser

Waukesha petition. The statement was made that “the EPA estimates that replacing formaldehyde testing with THC testing would result in substantial compliance cost savings annually while achieving the sa me reduction in HAP emissions,” This comment by the EPA has painted the FTIR manufacturing and testing services industry with a wide brush and publicly labeled them as “too complex and costly” without having data of any kind to support that statement or co nclusion.

3. The Dresser

- Waukesha petition submitted data attempting to demonstrate that CO was an adequate surrogate for HAP and/or formaldehyde. In their own study, they had
demonstrated R 2 values of 0.5 to 0.65 for correlation between CO and formaldehyd e for a single engine speed. An R 2 value of 0.50, simply stated, means that only 50% of variance of the formaldehyde measurement can be explained by the CO measurement. This does

not mean that 50% of the time the measurement is correct rather that only 50% of the understanding of the emission has been described. In the s ocial s ciences that would indicate a level of correlation; however, in the physical s ciences an R 2 less than 0.90 suggests that a significant degree of variability exists betwe en the known and the predicted, and an R 2 of 0.50, would suggest very little correlation. Furthermore an R 2 of 0.50 with the condition that the engine is running at specific set points further reduces its predictive ability. For further explanation of thi s lack of correlation

, se e Appendices C &

D

.

4. D ata submitted in the ICAC ’s comments from actual SI 4SLB and 4SRB compliance test data showed that there was little to no correlation between the CO, VOCs and formaldehyde. It was also demonstrated that the formaldehyde emission from SI 4SLB engines is mostly due to CH 4 partial oxidation in the exhaust system, not due to the primary combustion (See Appendix D). Similar results were also shown for SI 4SRB engines

. Formaldehyde that is ultimately emitted fro m these sources is generated by a
different mechanism than the CO and VOCs. The reason there is little to no correlation is because the formaldehyde concentration in both SI 4SLB and 4SRB is due to the
oxidation of the CH 4 slip (which can be significant, 1,000’s ppm), the O 2 level, the flow rate through the catalyst or exhaust train and the temperature of that exhaust train and7

catalyst. The formaldehyde emission in a properly running exhaust system from a natural gas fired engine is not due to the primary combustion, or rel ated to CO and VOCs. The catalyst data presented below clearly show that the formaldehyde from the engine exhaust is eliminated by the catalyst and then recreated as the temperature of the catalyst (and exhaust manifolds) rises towards the operating range . Thus, the conclusions drawn from
the data in the Dresser

- Waukesha petition are erroneous and not based upon proper scientific principles, and their acceptance should be questioned, especially considering that direct HAP measurements could be performed l ess expensively.

V. Conclusion

The data provided demonstrate that there is no correlation and why there is no correlation between VOC: CO: formaldehyde for either SI 4SLB or SI 4SRB engines for real world engine

exhaust data. The industry provided no recen t cost data demonstrating that HAP (formaldehyde) monitoring has any overly burdensome cost on the industry

. In fact, with current RICE

- MACT testing costs in the $1,400 to $3,500 range for these compliance tests anywhere in the contiguous US, there appear s to be no reason to allow for surrogates to HAP/formaldehyde testing for either SI 4SLB or SI 4SRB engines

.

Finally, a s provided in the appendices, there are many small businesses that have spent significant sums of money to buy state

- of

- the

- art technology to be able to perform this testing.
The se companies will be harmed if this final rule is not reconsidered and modified. Lastly, there are a number of small businesses that create the catalysts for these engines that will also be negatively aff

ected

. These companies hire hundreds of workers throughout the US and pay local, state, and federal taxes, and develop innovative new technologies.

Thank you for your consideration of the above issues. If you have any questions, please do not
hesitate to call me at (202) 367

- 1260.

Sincerely,

Betsy Natz,
ICAC Executive Director8 Appendix A

RICE

- MACT FTIR Emission and Energy Testing Groups

This appendix contains a list of source emission testing companies and energy companies that have spent significant resources preparing their companies to offer low cost high quality testing
for RICE

- MACT JJJJ and ZZZZ engine testing by FTIR EPA Method 320 or ASTM D6348 Methods. Most have also received training by industry experts to assure the quality of t he data
collected. A ll of the se source testing companies have already purchased the necessary equipment to measure CO/NOx/VOCs and HAPs cost effectively by FTIR from RICE

- MACT engines

. As can be observed in this list there are companies throughout the US t hat are offering these testing services, so that the tests can be performed anywhere in the continental US with very low cost to the Natural Gas Industry. ( See Appendix B for RICE

- MACT test pricing by EPA
Method 320 or ASTM D6348 )

.

Company Location

Air Compliance Consultants 1050 William Pitt Way, Pittsburgh, PA 15238

Air Hygiene 1600 W. Tacoma Street, Broken Arrow, OK 74012 Additional offices in Shreveport, LA; Fort Worth, TX; Houston, TX; and mobile laboratories in Atlanta, GA; Las Vegas, NV; and Philadelphia, PA

B.enviroSAFE 601 Lonesome Prairie Trail, Haslet, TX 76052 Additional office in Tulsa, OK

CET 400 S. Bloomfield Blvd., Bloomfield, NM 87413

CST 10935 Argonite Dr. NW, Albuquerque, NM 87114

Envirotech Inc 5796 US Highway 64, Farmington, NM 87401

ESS Inc. 436 Raleigh Street, Wilmington, NC 28412

Liberty Testing LLC 113 CR 2213, Cleveland, TX 77327

EQT EQT Plaza, 625 Liberty Avenue, Suite 1700, Pittsburgh,
PA 152229 Additional offices throughout Northeast and Mid

- Atlantic
States

EMIT 772 Airfield Lane, Sheridan Wyoming 82801 Additional offices in Fort Worth, TX; Houston, TX; Farmington, NM; Oklahoma City, OK and Grand Junction,
CO

Empire Stack Testing, LLC 5252 Ramsey Road Ashville, NY 14710

Enerven 15505 Wright Brothers Dr. Addison, TX 75001 Now (J

- W Energy Company) Additional offices throughout US

EnRUD Resources, Inc 1006 Vista Road, Pasadena, TX 77504

Entech Eng 4 South Fourth Street, P.O. Box 32, Reading, PA 19603

- Additional offices in Mountaintop, PA; Pottsville, PA; Lititz, PA

Exterran 16666 Northcase Dr., Houston, TX 77060
Additional offices all over the world

Golden Specialty 931 Seaco Ct, Deer Park , TX 77536

Graystone 1551 N. Hwy 69, Atoka, OK 74525

McClung 234 Johnny Clark Road, Longview, TX 756034

- 4319

MEI 2525 E. Interstate 20 Midland, TX 79701
Additional o ffices in Weatherford, TX

Nordon Corporation P.O. Box 1415, Round Rock, TX 78680

Oasis Emission Consultants, Inc 44 Fort Road, Sheridan, WY 82801 Additional offices in Rock Springs, WY and Gillette, WY

Pace Analytical Inc 1800 Elm Street SE, Minneapolis, MN 55414
Additional o ffices throughout US

STORM 4219 Rosewood Rd. Schnecksville, PA 18078

TRC Environmental Corp. 9225 U.S. Highway 183 South, Austin, TX 78747 Additional offices throughout US10

Windrock

– 1832 Midpark Rd., Suite 102, Knoxville, TN 37921 Additional offices throughout Northeast and Mid

- Atlantic
States11 Appendix B

RICE

- MACT FTIR NO/CO, JJJJ, ZZZZ Test Costs

T he Dresser

- Waukesha p etition suggested that HAP testing for RICE

- MACT engines is a costly
burden on the n atural g as i ndustry , yet it did not provide any costs to demonstrate this burden.
Below are approximate 2012 price ranges from 12 companies

, listed by their main testing headquarters state

, for RICE

- MACT engine testing for NO/CO, JJJJ and ZZZZ testing. These companies perf

orm testing in the Northeast, Mid

- Atlantic , Southeast, Midwest, Mountain, Southwest, and West regions. As seen in the table below, the cost for a single full NO/CO, JJJJ, ZZZZ compliance test is in

- line if not lower than traditional CO testing. Pricing c ould be even lower given more competition and a larger engine base to test. If inlet/outlet CO testing is used to demonstrate compliance, that testing can be more expensive than performing EPA Method 320 or ASTM D6348 where CO/NOx/VOCs and HAP (formaldehy de) directly. Many of these companies listed have traditional portable testing capability, and most if all will agree that FTIR testing (through the above methods) is easier and provides greater confidence in the final data. By u sing newer technology wit h EPA Method 320 or ASTM D6348, better data are collected that can be validated, at lower or equivalent costs and allows for the direct reading of HAPs such as formaldehyde.

The EPA also added a rural rule based on economic and logistical reasons for not testing a certain set of engines. In the emission testers list below, all of these companies have built or purchased fully self

- contained measurement systems that can be mobilized to nearly any location without need for local power or assistance

. Also, in most cases the price to perform the RICE

MACT test by EPA Method 320 or ASTM D6348 is the same no matter the location of the engine.

Please note that the price ranges in the table below are not all base prices. Some include travel and some do not; some companies vary their prices based on the number of engines tested and allow discounts for multiple engines; higher prices may reflect s pecial testing circumstances, such as inlet/outlet testing.

Main Location NO/CO JJJJ ZZZZ

Oklahoma $1,500

- $ 2,500 $ 1,850

- $3,500 $ 1,850

- $5,000

Pennsylvania $2,000

- $ 7,500 $2,000

- $ 7,500 $2,000

- $ 7,500

Texas $1,400

- $ 3,150 $1,400

- $ 4 ,500 $1,400

- $ 5,900

Wyoming $ 1,800

- $4,800 $2,500

- $4,800 $2,500

- $4,80012 Appendix C

No Correlation between CO/VOCs and HAP for SI

- 4SLB or SI

- 4SRB RICE

In ICAC ’s comments, data were submitted demonstrating why CO should not be allowed as a surrogate for HAP in either a SI

- 4SLB or a SI

- 4SRB engine no matter the engine horsepower.
The data also demonstrated how the CO, VOCs, and formaldehyde vary in real life engines during actual com pliance tests. The following data are being resubmitted and are a subset of data collected over the last year from a number of testing firms.

Fifty

- six lean burn compliance data sets were performed following ASTM D6348. Each test had CO, VOC

, and formald ehyde data collected and were from 5 emission testing firms. These data
are tabulated below for each of the 3

- one hour tests. As can be observed from these data, the CO can be 10 times or more than the formaldehyde level and at other measurements 3 times less or lower. From these 56 randomly selected tests on engines that were prepped for the impending compliance test, there appears to be no correlation between CO and formaldehyde.

It also has been suggested that VOCs could be used a surrogate for HAP as well. Again from the data below, the formaldehyde is shown to be anywhere from 3 times lower to 8 times higher than the respective VOC.

Hundreds of other data sets demonstrate the same conclusion that there is little to no correlation
between formaldehyde and CO or formaldehyde and VOC within a standard compliance test on a
SI

- 4 stroke lean burn engine. Also, all of these data were collected using a single FTIR gas analyzer so there were no additional costs to collect the formaldehyde informa tion as is suggested by the industry. Since there is limited correlation and limited to no additional costs for measuring formaldehyde, the question arises as to why would one want to depend on a surrogate
when the information is available with current EPA recognized technology following recognized protocol

.
In the data provided, if CO were used as a surrogate, there are potentially times when the formaldehyde would be grossly overestimated causing an apparent failure of the compliance test.
This scen ario is certainly every bit as possible as the converse where the CO is low and the formaldehyde is high as the data below clearly demonstrate.1314

Rich burn engines, when running correctly, produce less formaldehyde than their lean burn
counterparts on aver age. However, if the purpose is to use CO or VOCs as a surrogate for formaldehyde, it must be demonstrated that a correlation exists. In the table below are 30 compliance tests on rich burn engines where the formaldehyde was below detection.

In these tes ts

, the CO 1 hour average varied from 16 ppm up to almost 700 ppm, yet no formaldehyde was detected. Also, there were significant variations in the CO concentration between the test runs that demonstrates the need for longer testing times. Since these co mpliance tests were not reporting VOCs they were not calculated and to do so would have required significant effort and time that was not available. These data could be provided if required by
the EPA to demonstrate the lack of correlation between VOC and formaldehyde.

Instead, since methane (CH 4 ) had been measured, its concentration was utilized as a predictor of the potential VOC. Certainly as stated above, there may or may not be a great correlation between methane and VOC but it just demonstrates that with almost a 10 fold change in average methane levels (~260 ppm to ~2600 ppm)

, no formaldehyde was observed.

That leads to the question of w hy the formaldehyde does not correlate to other combustion byproducts like CO and VOCs during real compliance test s of a natural gas fired SI

- 4SLB and
SI

- 4SRB reciprocating internal combustion engines

. The data presented in Appendix D explain why there is no correlation between CO/VOCs and formaldehyde for these natural gas fired engines.1516 Appendix D

Why there is no correlation between CO/VOCs and Formaldehyde

Why is the formaldehyde concentration not correlated to CO and VOCs in either lean or rich burn engines? It is most likely due to the formaldehyde being formed by a different chemical pathway. What differen t pathways are present? One in particular is the catalyst chemistry itself. When the gases interact at the catalytic surface, CO, formaldehyde and VOCs react differently and the resultant mixture can and does change.

To determine if this was possible, bo th lean burn and rich burn catalyst cores were obtained and simulated combustion mixtures were passed through them at varying temperatures and flow rates. Gas mixture measurements were performed just prior to the catalyst and just after the catalyst. The percentage of formaldehyde remaining was calculated for different catalyst temperatures and flows (GHSV

– Gas Hourly Space Velocities).

In the lean burn experiment tabulated below the formaldehyde dropped to a few percent of its original concentration ver y quickly at low temperatures and at all flow rates. However, as the catalyst temperature was raised to near the normal operating temperatures the formaldehyde returned at levels exceeding 60% of the original concentration. What happened in these experim ents? Does formaldehyde not react at these higher temperatures and flows?

To try to understand what was happening, the experiment was repeated with no formaldehyde in the simulated engine exhaust mixture heading to the catalyst. When that was done, almost identical levels of formaldehyde were observed at the post catalyst measurement point. So the conclusion drawn initially was the following: formaldehyde appears to be forming on the catalyst17

or the reactor walls due to the partial oxidation of met hane (100s to 1000s of ppm are present in the lean burn exhaust). The formaldehyde emission from a lean burn engine would not be expected to correlate to the combustion gases but be correlated to the methane exhaust concentration, the oxygen concentration , the catalyst (or exhaust) temperature, the age of the catalyst and the gas flow rate through the catalyst. Therefore, the use of combustion gases as surrogates or predictors of the HAP or formaldehyde is flawed since they are not generated during the sa me reaction chemistry.

Two additional experiments were also performed to further understand what might be happening to generate the observed formaldehyde. First, a more limited test was performed with and without CO to make sure that the post catalyst for maldehyde was not somehow related to the CO
concentration. With or without CO in the simulated exhaust had no effect on the formaldehyde formation and similar post catalyst formaldehyde concentrations were observed in both. In the
second test the lean bu rn catalyst was replaced with a blank core to determine if it is potentially a hot metal surface affect and not the catalyst. When this experiment was performed, up to a 200% formaldehyde post response was observed. This suggests that the hot metal in th e exhaust may be playing a significant role in the formation of formaldehyde and that the catalyst role might be minimal. It would also further suggest as a catalyst ages its ability to oxidize this generated formaldehyde would be reduced and the emission level would further increase. Additional research needs to be performed to understand the contribution of both to the final
exhaust. However, it is clear that formaldehyde seen at the higher catalyst temperatures and seen during many SI

- 4SLB engine compl iance tests is most likely due to CH 4 partial oxidation in the exhaust and not due to the original engine combustion.

A similar experiment was constructed for rich burn catalysts. In this experiment it was noted that formaldehyde was reduced effectively at most temperatures and flows. But formaldehyde was still observed near the midpoint of the temperature range at the lower flow rates. Once again there are conditions that can be present in the exhaust stream that would be conducive to formaldehyde formation at the catalyst or within the exhaust housing. Again it would not be prudent to base the formaldehyde concentrat ion or other HAP concentration on a surrogate, when so many unmeasured variables determine the exhaust HAP concentration (CH 4 slip, O 2 concentration, linear flow rate, exhaust temperature

, and catalyst age); especially when HAP/formaldehyde can be measured directly at no additional cost.1819 Appendix E

Example of Rich Burn Engine Variability

An engine emission data set from just prior to and then during a rich burn compliance test are displayed below. As is observed, just prior to the rich burn test the CO, VOCs, NH 3 and NOx are all very high and yet no formaldehyde is observed. So, once again CO and VOCs would not be a good predictor of the formaldehyde concentration for this rich burn engine at any setting.

These high CO and NOx emissi on levels suggest that the engine requires tuning to pass a compliance test. Subsequent to that engine tuning, the 3

- one hour compliance test proceeds. During this compliance test, significant variations in all but the formaldehyde concentrations are
sti ll observed. This exhaust variability and initial tuning demonstrates that these rich burn engines if not monitored or tested annually could allow for significant emission amounts of CO and NOx. It also demonstrates why 15 minute tests are not adequate t o provide an accurate picture of the true exhaust.

Allowing engines to operate untested or tested for very short periods would nearly guarantee that they would all be running similar to the section in yellow below. As these gases move from “rural” to pop ulated areas of the country, the air quality would be further negatively affected and could potentially cause non

- attainment to occur more frequently as more and more engines are added to the pipeline.

At a minimum the EPA should at least review the curren t operating status of some of these “rural” engines or discuss procedures with emissions testing companies before making sweeping
decisions with little to no factual information.

This source test d ata from a Rich Burn Engine clearly demonstrates that the re is no correlation to THC, CO, and formaldehyde and that CO concentration clearly vary by very large concentration changes over any 1 hour period.