Air and Radiation EPA420-R-05-009

June 2005

Analysis of New York’s

Request for Waiver of the

Reformulated Gasoline

Oxygen Content

Requirement for New York

Covered Area:

Technical Support Document
EPA420-R-05-009

June 2005

Analysis of New York’s Request for Waiver of the

Reformulated Gasoline Oxygen Content

Requirement for New York Covered Area:

Technical Support Document

Transportation and Regional Programs Division

Office of Transportation and Air Quality

U.S. Environmental Protection Agency

Docket OAR-2003-0004

Document Number III-B-1
i

TABLE OF CONTENTS

EXECUTIVE SUMMARY ............................................... 1

I. BASIS FOR DEC’S REQUEST FOR A WAIVER ........................... 5

II. GENERAL CONCLUSIONS EPA CAN MAKE ABOUT EMISSIONS BASED ON

DEC’S SUBMISSION AND OTHER INFORMATION AVAILABLE .......... 6

III. INFORMATION NEW YORK HAS PROVIDED TO EPA .................. 9

A. Information on VOC emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

B. Information on NOx emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

C. Information on CO emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

D. Information on likely oxygenated RFG composition subsequent to New York’s

ban on MTBE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

E. Information on likely RFG composition subsequent to a waiver of the

oxygen content requirement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

IV. INFORMATION NEEDED TO EVALUATE NOX, VOC AND CO EMISSIONS

CHANGES RESULTING FROM AN OXYGEN CONTENT WAIVER . . . . . . . 14

A. Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

B. Emissions Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

C. RFG Properties and Composition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

V. EMISSIONS-RELATED CONCLUSIONS BASED ON NEW YORK’S

SUBMISSION

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

A. Effect of a waiver on NOx emissions based on New York’s submission . . 20

1. Multiple gasoline properties affect NOx emissions . . . . . . . . . . . 20

2. NOx emissions from on-road vehicles with and without a waiver 21

3. NOx emissions from non-road vehicles with and without a waiver 22

B. Effect of a waiver on VOC emissions based on New York’s submission 22

1. VOC on-road and non-road exhaust emissions . . . . . . . . . . . . . . . . 23

2. Evaporative VOC emissions due to RVP increases . . . . . . . . . . . . . 24

3. Evaporative VOC emissions due to permeation . . . . . . . . . . . . . . . . 26

C. Effect of a waiver on CO emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

D. Ethanol transport-related emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

VI. CONCLUSIONS OF EPA’S ANALYSIS OF DEC’S SUBMISSION . . . . . . . 28
ii

APPENDIX A: SUMMARY OF EPA’S ANALYSIS OF DEC’S SUBMISSION . . . . . . 29

APPENDIX B: EPA’S RESPONSE TO DEC’S REASONS FOR NOT PROVIDING

INFORMATION THAT EPA REQUESTED . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
1

EXECUTIVE SUMMARY

Section 211(k)(1) of the Clean Air Act (CAA) requires that the Administrator of

the Environmental Protection Agency promulgate regulations establishing requirements

for reformulated gasoline (RFG) to be used in gasoline-fueled vehicles in specified

ozone nonattainment areas. The CAA mandates RFG use in certain nonattainment

areas, based on ozone air quality and population criteria. Other ozone nonattainment

areas are allowed to opt into the RFG program. Within the state of New York, RFG is

mandated in the New York City Consolidated Metropolitan Statistical Area (CMSA). 

Dutchess County, New York is an opt-in area.

Section 211(k)(2)(B) of the Act, 42 U.S.C. § 7545(k)(2)(B), establishes an oxygen

content requirement for federal RFG, but allows EPA to waive compliance with the

requirement under certain circumstances. Section 211(k)(2)(B) provides that:

The oxygen content of the gasoline shall equal or exceed 2.0 percent by

weight (subject to a testing tolerance established by the Administrator)

except as otherwise required by this Act. The Administrator may waive, in

whole or in part, the application of this subparagraph for any ozone

nonattainment area upon a determination by the Administrator that

compliance with such requirement would prevent or interfere with

attainment by the area of a national primary ambient air quality standard. 

In a letter dated January 6, 2003 from New York State Department of

Environmental Conservation (DEC) Commissioner Erin Crotty to then Administrator

Whitman, New York requested a waiver from the federal oxygen content requirement

for reformulated gasoline. The submission asserted that because MTBE would be

banned in the State of New York beginning January 1, 2004, and because of the Clean

Air Act’s oxygen requirement, ethanol would be used as an oxygenate in the RFG areas

in New York State. DEC further argued that the use of ethanol as a replacement for

MTBE in RFG would result in an increase in volatile organic compounds (VOC) and

oxides of nitrogen (NOx) during the summer ozone season, and that these increases

would prevent or interfere with New York’s ability to demonstrate reasonable further

progress to attain and maintain the National Ambient Air Quality Standard for ozone in

its RFG areas. 

EPA determined that DEC’s submission did not contain sufficient information and 

because New York’s submission failed to address the requirements in the statute, EPA
1 Docket OAR-2003-0004, Document II.C.1.

2 Docket OAR-2003-0004, Document II.D.6.

3 DEC’s stated reasons for not providing the information requested by EPA, and EPA’s

responses to those statements (that are not otherwise addressed in the TSD), are set

forth in Appendix B to the Technical Support Document.

2

notified NY that technical and supporting information was needed for EPA to evaluate

the merits of the request. In a letter to DEC dated April 1, 2003, EPA requested

clarification and additional information.1

 A subsequent submission dated December 12,

2003 from DEC acknowledged EPA’s April 1, 2003 request for additional information.2

DEC provided some additional information in support of its waiver request with this

correspondence, but generally did not provide the information requested by EPA, for

reasons set forth in its letter.3

In order to determine whether the RFG oxygen content requirement prevents or

interferes with New York’s ability to attain National Ambient Air Quality Standards

(NAAQS), it is necessary to consider the gasoline quality and related emissions impacts

that would be likely to exist with and without the RFG oxygen content requirement. In

the case of New York, attainment of the ozone NAAQS is the only issue raised by New

York DEC. To evaluate the potential for interference, EPA must first consider the

emissions differences for each pollutant contributing to ozone formation (NOx, VOC and

carbon monoxide (CO)), between cases where the oxygen requirement remains in

effect (“no-waiver”) and cases where the oxygen requirement is waived (“waiver”). In

deciding whether to grant or deny a waiver, as a threshold matter EPA must determine

what difference, if any, a waiver would have on emissions, and what effect, if any, the

difference in emissions would have on ambient ozone levels.

Certain underlying information is required in order to make a quantitative

estimate, or even a reasonably certain qualitative directional estimate of the emissions

changes that might occur from a waiver. This information includes knowledge of certain

emission-related fuel properties of the RFG that would be supplied to New York with

and without a waiver. Models relating these fuel properties to vehicle emissions would

then be used to estimate percent differences in emissions between the “no waiver” and

“waiver” conditions. Additionally, area-specific on-road and off-road gasoline emission

inventory data are needed in order to convert relative (%) changes to absolute

(tons/day) changes.

 New York DEC’s submissions did not include quantitative estimates of the

emissions differences between “no waiver” and “waiver” scenarios for any of the

pollutants contributing to ozone formation, NOx, VOC and CO. While New York’s

submissions did contain quantitative estimates of certain VOC emission changes that

could be associated with the change from MTBE use to ethanol use, these estimates

were incomplete and in some cases unsupported. Changes in NOx emissions from
3

MTBE use to ethanol use were not quantified and changes in CO emissions were not

addressed in New York’s submissions. 

If New York had provided quantitative estimates of the emission differences

between the “no waiver” and “waiver” situations, EPA‘s evaluation of its waiver

submission would have included a thorough review of the basis for these estimates (fuel

property estimation and emission modeling methodology), and subsequently, a

thorough review of whether these emission differences indicate that ambient ozone is

likely to be higher with the oxygen requirement than without. However, EPA’s initial

review of the information contained in DEC’s waiver submissions determined that it

lacked not only the quantitative estimates of the “no waiver” to “waiver” emission

changes, but the underlying information necessary to make such estimates. 

Consequently, EPA asked for additional information and analyses that are 1) necessary

to estimate the effect a waiver might have on the properties of New York reformulated

gasoline, and 2) the effect that this change in fuel properties would have on emissions

from highway and off-road vehicles and equipment. Since this information has not been

submitted, EPA is unable to determine whether implementation of the oxygen content

requirement in the New York RFG area will prevent or interfere with the attainment of a

NAAQS.

 EPA has considered the information that New York has provided which may be

relevant to an analysis of New York’s waiver request. EPA has determined that the

relevant no-waiver to waiver comparison cannot be made either qualitatively or

quantitatively. In making this evaluation, EPA has considered the information provided

by New York with regard to the potential effect of a waiver on each of the pollutants,

NOx, VOC and CO, for both on-road and off-road gasoline vehicles and engines.

In order to evaluate the information submitted by New York, we have identified

the fuel properties, vehicle fleets (e.g., on-road versus off-road, older technology

vehicles versus newer technology, etc.), and emission sources (e.g. exhaust, “as

blended” evaporative, commingling and permeation-related) that would need to be

considered in a waiver/no-waiver analysis. We have also identified emissions models

and other information necessary to make the relevant emission estimates that could be

utilized to make the waiver/no-waiver comparison.

The information that DEC has provided fails to clearly demonstrate what effect a

waiver would have an on ozone levels in New York. This is because: 1) there are three

pollutants whose emission rates could be altered by a waiver, (NOx, VOC and CO) and

all three affect ozone formation to varying degrees, 2) the lack of information on fuel

qualities with and without a waiver and the lack of other relevant and necessary

information precludes even a directional estimate of the impact of a waiver on NOx and

VOC emissions, 3) the best estimate of the net impact of a waiver on CO emissions is

that CO emissions would be greater with a waiver than without, but the difference

cannot be quantified and 4) no analysis has been provided or performed, and the

information before the agency does not allow an analysis to be performed, on the
4 CO plays a far less important role in ozone formation that NOx or VOC. Thus, even

though a gross directional determination can be made for CO, such a determination

provides little information in making an overall judgement about ozone formation.

5 New York has not raised any issue concerning interference with attainment of the

particulate matter (PM) NAAQS. However, our conclusions regarding the PM NAAQS

would be the same as those regarding the ozone NAAQS, i.e., New York has provided

insufficient information to clearly demonstrate what effect, if any, a waiver would have on

PM. This is because New York has not provided sufficient information to determine PMrelated emissions for the no waiver and waiver comparison.

4

combined effect of these emissions changes on ozone.4

 Since no determination can be made regarding the overall effect of a waiver on

ozone-related emissions, the information that DEC has provided fails to clearly

demonstrate what effect a waiver would have on ozone. Since this threshold

demonstration has not been made, EPA is not able to determine whether the oxygen

requirement for RFG interferes with attainment of the ozone NAAQS in the New York

RFG area. EPA concludes that New York’s request therefore should be denied.5
5

I. BASIS FOR DEC’S REQUEST FOR A WAIVER

As EPA interprets it, New York’s request for a waiver is based primarily on DEC’s

contentions that use of ethanol-oxygenated gasoline will interfere with attainment of the

ozone NAAQS because:

• The NOx and VOC emissions performance of ethanol-oxygenated RFG will be

worse than the emissions performance of the MTBE-oxygenated RFG supplied

to New York prior to its MTBE ban. 

• Commingling and permeation resulting from ethanol use will increase VOC

emissions compared to MTBE-oxygenated RFG.

• Ethanol-oxygenated RFG will not provide the NOx reduction benefits expected

under the RFG program because the Complex Model does not fully capture the

effects of oxygenates on vehicle emissions of NOx.

• Relaxation of the RFG VOC performance standard for 10 percent ethanol blends,

or granting of 1 psi volatility waivers for 10 percent ethanol blends could increase

VOC emissions.

• There would be emissions associated with ships and barges transporting ethanol

into the NY area for adding to RFG at terminals.
6 Although comparing emissions associated with MTBE-oxygenated RFG to ethanoloxygenated RFG is not the relevant question for EPA’s decision on New York’s waiver

request, EPA notes that the proffered analysis is inadequate. While EPA agrees with

certain of New York’s assertions (e.g., permeation from ethanol and commingling of

ethanol and non-ethanol fuels lead to VOC emissions increases, and there are much less

VOC emissions from these pathways with MTBE use), EPA disagrees with others (e.g.,

the assumptions that VOC emissions will increase with ethanol use as a result of a

volatility waiver or VOC adjustment regulation, discussed below). Furthermore, there are

other considerations related to a switch from MTBE to ethanol that New York simply

ignores, such as differences in the composition of MTBE-oxygenated and ethanoloxygenated RFG that may result in emission differences. When all relevant factors and

available information are considered, EPA also cannot determine what the effect on

ozone formation will be from a switch in New York from MTBE-oxygenated RFG to

ethanol-oxygenated RFG.

7 Although the program report enclosed with DEC’s December, 2003 submission included

analyses for the gasolines used in a DEC test program discussed in sections III-C and IIID below, DEC has provided no basis for EPA to conclude that these formulations are

likely to represent the gasoline that would be supplied were a waiver granted. All fuels

met the 30 ppm sulfur standard. However, the report notes that the ethanol RFG and

non-oxygenated equivalent RFG test fuels were specified to have Complex Model

performance similar to the study MTBE RFG. The MTBE RFG was specified, except for

sulfur, to represent “typical year 2000 NYCMA RFG”. No other restrictions or

specifications were imposed on the fuel supplier. As noted, the composition and

emissions performance of actual RFG with or without a waiver will be determined by a

number of regulatory, economic and technical constraints. Consequently the

specifications DEC imposed on the test fuels are insufficient to ensure that they will be

similar to actual future RFG, with or without a waiver.

6

II. GENERAL CONCLUSIONS EPA CAN MAKE ABOUT EMISSIONS BASED ON

DEC’S SUBMISSION AND OTHER INFORMATION AVAILABLE

The only emission modeling which DEC submitted in its January 6, 2003 waiver

request was characterized in its December 12, 2003 letter as “reflecting the potential

impact of ethanol as an oxygenate replacement for MTBE.”6 DEC provided no

information on the likely properties of the oxygenated or non-oxygenated RFG that

would be supplied to New York with a waiver, nor has DEC discussed the market share

of non-oxygenated RFG market share should a waiver be granted.7 The only

information supplied by DEC on oxygenated RFG without a waiver is that it is likely to

contain ethanol at 10% by volume. As discussed in Section IV of this document,

information on likely fuel properties would be critical to an estimation of the emissions

differences between the waiver and non-waiver scenarios in New York, as is evidenced
8 Ethanol-oxygenated RFG could constitute a portion, potentially a substantial portion, of

New York’s gasoline pool even if a waiver were granted. DEC may have implicitly

assumed in their submissions that all RFG would be non-oxygenated if a waiver were

granted, but it has provided no information or analysis, such as refinery modeling, to

substantiate this position. This is an issue not only because the pool average emissionrelated property values of New York’s “waiver” RFG would depend on the extent to which

ethanol is used, but because substantial market shares of both ethanol RFG and nonoxygenated RFG in New York could result in “worst case” commingling-related VOC

emissions.

9 In the California waiver analysis, EPA evaluated twelve “no waiver” to “waiver” scenarios. 

Each scenario consisted of a set of “no waiver” and “waiver” fuel properties predicted by

refinery modeling with a specific set of assumptions. EPA treated the “no waiver” case as

the reference, computed percent differences in emissions between “no waiver” and

“waiver” fuels, and applied these percent differences to emission inventories to determine

tons/day differences in NOx, VOC and CO emissions. EPA assumed that the tons/day

emission inventory information that was available for the California analysis represented

the all ethanol-oxygenated “no waiver” reference condition. EPA was therefore able to

compute “no waiver” to “waiver” tons/day differences from percent differences in a single

step. While it would be possible in a waiver analysis to calculate emissions changes from

a different reference condition than the “no waiver” baseline, it still necessary to make a

“no waiver” to “waiver” emissions comparison. If a different reference condition (e.g. preMTBE ban) were used, it would be necessary to first estimate both reference to “waiver”

and reference to “no waiver” percent change and tons per day emissions changes, and

7

by EPA’s evaluation of California’s waiver request. 

In other words, DEC has asked EPA to grant a waiver of the RFG oxygen

requirement, based solely on its assertion that NOx and VOC emissions will increase

with RFG using ethanol when compared to the use of RFG oxygenated with MTBE. 

There is a very fundamental problem with New York’s analysis. In focusing on the

effect of switching from MTBE use to the use of ethanol as an RFG oxygenate, New

York is addressing the wrong question. In light of New York’s ban on the use of MTBE

as an oxygenate, EPA must compare the base case of ethanol-oxygenated RFG

without a waiver to the RFG that would be supplied if an oxygen content waiver were

granted. This is the proper comparison for determining whether continuing to maintain

the oxygen content requirement interferes with attainment of the ozone NAAQS. The

properties of MTBE-oxygenated RFG are irrelevant to this analysis. To put it another

way, maintaining the current oxygen content requirement could not amount to

interference, unless, at a minimum, a waiver is likely to produce a better situation with

respect to ozone-forming pollutants than would exist absent the waiver. As noted, DEC

has not provided information regarding the emission-related properties of the RFG that

would be supplied were a waiver granted, nor did it address the issue of nonoxygenated RFG market share were a waiver granted.8

 As noted, DEC has not

provided the kinds of information necessary to reach this conclusion. In summary, with

the information at hand, EPA cannot estimate no-waiver to waiver emission changes,

as it must do to ascertain whether the oxygenate requirement interferes with NAAQS

attainment.9

 This general conclusion is explained in more detail below with respect to
subsequently combine them to estimate the total “no waiver” to “waiver” changes. 

8

each individual pollutant of concern.

Below are more detailed discussions of the information submitted by NY. The

following sections of this TSD discuss EPA’s evaluation of the information. Our

evaluation clearly shows that the information is insufficient to come to any definitive

conclusion regarding the effect of an oxygen waiver on ozone.
10 Filed in docket OAR-2003-0004, document number II.D.1 

11 Permeation refers to the escape of gasoline constituents through the walls of non-metallic

fuel lines and gasoline tanks. These soft components of automotive fuel systems tend to

be more permeable to ethanol than to other hydrocarbons in gasoline. Thus, ethanol9

III. INFORMATION NEW YORK HAS PROVIDED TO EPA

In a letter dated January 6, 2003 from New York State Department of

Environmental Conservation (DEC) Commissioner Erin Crotty to then Administrator

Whitman, New York requested a waiver from the federal oxygen content requirement for

reformulated gasoline, under Section 211(k)(2)(B).10 The submission stated that

because MTBE would be banned in the State of New York beginning January 1, 2004,

and because of the Act’s oxygen content requirement, ethanol would be used as an

oxygenate in the RFG areas in New York State. DEC stated that the use of ethanol as

a replacement for MTBE in RFG would result in an increase in volatile organic

compounds (VOC), and oxides of nitrogen (NOx) during the summer ozone season. 

DEC further stated that “increases in these pollutants will immediately interfere with

New York’s ability to demonstrate reasonable progress to attain and maintain the

federal ozone standard...”.

In a letter dated April 1, 2003 to DEC Commissioner Erin Crotty, EPA asked for

additional information in order to evaluate DEC’s request for a waiver. A subsequent

submission dated December 12, 2003 from DEC acknowledged EPA’s April 1, 2003

request, and provided some limited additional information, but failed to provide the

information requested. 

In the sections below, EPA describes in detail the information that DEC has

submitted in detail.

 

A. Information on VOC emissions

DEC argues that the use of ethanol as a replacement oxygenate for MTBE will

result in substantial increases in VOC emissions due to (1) increased permeation

through vehicle components that hold gasoline, (2) commingling of ethanol-blended

fuels with fuels that do not contain ethanol, and (3) possible modifications in regulatory

limitations on fuel volatility.11 DEC has estimated that the use of gasoline with 10%
RFG blends tend to result in an increase in evaporative emissions due to permeation

through these components. Commingling refers to the RVP increase (with resultant

emission increase) that occurs when non-ethanol and ethanol-oxygenated gasoline

blends are mixed in the gas tanks of consumer’s automobiles. Since the presence of

ethanol causes an increase in the volatility of the gasoline (as measured by the Reid

Vapor Pressure or RVP), such commingling would contribute to an increase in

evaporative VOC emissions. The regulatory changes New York refers to concern

regulations that provide an allowance for higher VOC emissions when ethanol RFG is

used in the Chicago and Milwaukee area, and potential allowances New York could

provide when blenders add ethanol to conventional gasoline. As is discussed in section

V.B.2 of this TSD, there is no basis to expect that such changes would occur and,

therefore, they are not relevant to an appropriate oxygen waiver analysis. 

10

ethanol in a fleet of five million vehicles would increase VOC emissions due to

permeation by 6.1 tons per day, as compared to use of gasoline with 0% ethanol. It has

provided some explanation of the methodology used in deriving this estimate (Enclosure

H of the January, 2003 DEC submission). DEC states that there would also be an

increase in VOC emissions due to commingling of ethanol and non-ethanol blended

gasolines, compared to before the MTBE ban, but does not provide a quantitative

estimate of the increase. 

DEC has also provided quantitative estimates of the VOC emissions increases

associated with a 0.3 pound-per-square-inch (psi) and 1.0 psi Reid Vapor Pressure

(RVP) increase, which DEC claims could occur if EPA were to adopt a VOC adjustment

rule for the NY area and if NY were to provide blenders of ethanol-oxygenated

conventional gasoline a volatility waiver. As is discussed in section V.B.2 of this

document, EPA believes that estimations of VOC increases associated with such

regulatory changes are irrelevant to the appropriate analysis for an oxygen waiver. 

Nevertheless, DEC estimated emissions increases of 30.2 tons/day with an RVP

increase of 0.3 psi statewide, 67.2 tons/day if there is an increase of 0.3 psi in RFG

areas and 1.0 psi in conventional gasoline areas, and 82.7 tons/day if there is an

increase of 1.0 psi statewide. Some details of their estimation methodology are

provided in enclosure G of their January, 2003 submission. 

DEC also notes that there will be emission increases (for both VOC and NOx)

due to the transport of ethanol to the New York City CMSA from production centers in

the Midwest, but has not provided a quantitative estimate of the emission increases that

will occur within the New York City CMSA. 

DEC has not identified or quantified any other VOC emission changes (increases

or decreases) that could occur with ethanol use, nor has it clearly stated that no other

significant VOC emission changes will occur. 

B. Information on NOx emissions

DEC claims that NOx emissions will increase with the use of ethanol blended
12 In essence, DEC is saying in its December, 2003 letter that ethanol will not affect exhaust

emissions in newer vehicles because fuel control systems will compensate for the

additional oxygen in gasoline. This appears to contradict the earlier argument that NOx

emissions from newer vehicles will increase with ethanol.

13 “Health, Environmental, and Economic Impacts of Adding Ethanol to Gasoline in the

Northeast States”; New England Interstate Water Pollution Control Commission,

Northeast States for Coordinated Air Use Management; July, 2001. See Volume 1, page

11 and Volume 2, page 11.

11

RFG compared to MTBE-blended RFG, but has not quantified the anticipated

increases. DEC stated in its January, 2003 letter that existing test data indicate that

NOx emissions from newer vehicles increase with ethanol, although it did not explicitly

define “newer vehicles”. In its December, 2003 letter, however, DEC states that vehicle

technology has rendered the need for an oxygen content requirement obsolete because

the fuel control systems in modern fuel injected vehicles will compensate for the

additional oxygen in gasoline and that oxygenated gasoline no longer provides a

benefit.12 Additionally, DEC states in its January, 2003 submission that data show that

ethanol causes NOx emissions increases in older vehicles and even more significantly 

in nonroad vehicles.

DEC notes that Phase II RFG regulations require refineries to produce gasoline

that reduces NOx emissions by 6.8 percent and VOC emissions by 27.4 percent

compared to 1990 levels, as quantified by the EPA Complex Model. DEC states,

however, that it believes that the EPA Complex Model does not fully capture the effects

that oxygenates such as ethanol have on emissions from current fleet vehicles. It

believes that NOx emissions will increase due to the use of ethanol compared to MTBE,

and that this actual increase in NOx emissions will not be identified by, or constrained

through the use of, the Complex Model to measure RFG compliance with phase II RFG

regulations. The basis for New York’s claim is a report prepared by NESCAUM and

submitted as enclosure B of their January 6, 2003 letter.13

C. Information on CO emissions

DEC made no explicit references to the potential effect of a waiver on CO

emissions or the relationship of CO to ozone formation in its January 6, 2003 or

December 12, 2003 letters, but appears to have implicitly claimed that a waiver would

have no effect on CO emissions from newer vehicles. As previously noted, DEC stated

in its December 12, 2003 letter that vehicle technology has rendered the need for an

oxygen content requirement obsolete because the fuel control systems in modern fuel

injected vehicles will compensate for the additional oxygen in gasoline. 

 DEC claimed that it has verified the lack of need for an oxygenate through

laboratory testing of two automobiles both with and without oxygenated fuel in a study

DEC provided, with its December 12, 2003 submission, entitled "Emission Impacts of
14 “Program Report: Emission Impacts of Fuels to Accommodate the NY State Oxy-waiver

Request and MTBE Ban", May 6 ,2003, submitted as an enclosure to DEC’s December

12, 2003 letter.

15 These emission-related properties are the parameters used in emission models to

estimate emission differences resulting from fuel formulation differences. The Complex

Model inputs affecting VOC and NOx emissions are RVP, oxygen wt%, aromatics vol%,

olefin vol%, sulfur ppm, E200 and E300. (E200 and E300 are the percent of gasoline

evaporated at 200F and 300F, respectively.) The alternative Tech 4 models which EPA

developed for its California waiver analysis use RVP, oxygen wt%, aromatics vol%, olefin

vol%, sulfur ppm, T50 and T90 as inputs . (T50 and T90 are the temperatures at which

50% and 90% of the gasoline are evaporated, and are highly correlated with E200 and

E300. ). As discussed later, these models should be applicable to a portion of New York’s

on-road fleet, as well. 

16 DEC does suggest that the as-blended Reid Vapor Pressure (RVP), could increase from

current levels, either because of a change in the RFG VOC emission performance

standard, such as that which EPA allowed in Chicago and Milwaukee (VOC adjustment

rule), or because of a 1.0 psi volatility waiver available for 10% ethanol-blended

conventional gasoline. As is discussed in section V.B.2 of this document, such changes

12

Fuels to Accommodate the NY State Oxy-waiver Request and MTBE Ban."14 This study

describes a test program conducted at DEC’s Automotive Emissions Laboratory (AEL),

in which two vehicles, a 1998 Plymouth Breeze and a 1997 Oldsmobile Achieva, were

tested multiple times using an MTBE-oxygenated RFG, an ethanol-oxygenated RFG,

and a non-oxygenated “equivalent RFG”. The program report concluded that data from

over 200 emission tests on these two vehicles do not indicate any consistent increase in

any of the regulated emission species (HC, CO, NOx) for either the ethanol-oxygenated

RFG or the non-oxygenated “equivalent RFG” relative to the MTBE-oxygenated RFG. 

D. Information on likely oxygenated RFG composition subsequent to New York’s

ban on MTBE

DEC has provided EPA with very little information on the likely emission-related

properties of its RFG subsequent to an MTBE ban.15 These properties will determine

the exhaust and evaporative emissions associated with RFG use in a non-waiver

scenario. 

NY stated in its December 12, 2003 letter that refiners will, almost uniformly, be

blending 10 (volume) percent ethanol. This is equivalent to approximately 3.5 weight

percent oxygen. Blending at approximately 5.7 volume percent ethanol is required to

meet the 2 weight percent RFG oxygen requirement, but, according to DEC, tax

incentives and other considerations will likely lead refiners to blend ethanol at 10%. 

Beyond this, NY has provided no further information on the probable composition of

ethanol-oxygenated RFG subsequent to its MTBE ban.16
are not expected to occur and, therefore, are not relevant to an appropriate oxygen waiver

analysis. 

13

The program report for DEC’s vehicle testing study, cited earlier, included

certificates of analysis showing properties for the gasolines used in the study. The

report states “AEL believes that the study fuel specifications approximate the fuel

blending situation that refiners will face upon implementation of the NY MTBE ban.” 

EPA is unsure if DEC was suggesting that the ethanol-oxygenated and non-oxygenated

RFG formulations described in the study are likely to represent New York’s RFG with

and/or without a waiver, subsequent to an MTBE ban. Since the ethanol-oxygenated

RFG formulation in this study was not blended with 10 volume percent ethanol, EPA

assumes that DEC would not consider it to be representative of New York’s “no waiver”

ethanol-oxygenated RFG.

E. Information on likely RFG composition subsequent to a waiver of the

oxygen content requirement

DEC did not explicitly address this issue in the text of either submission letter. 

Except as noted in the previous section and in footnote 7, DEC provided no description

of the potential composition of RFG were a waiver granted.
17 Since much RFG overcomplied with toxics performance requirements, MSAT imposes a

tighter constraint on RFG composition than the RFG performance standard for many

suppliers.

18 The sulfur level in RFG is currently constrained by RFG performance standards, but the

Tier 2 sulfur content requirement imposes a tighter constraint.

14

IV. INFORMATION NEEDED TO EVALUATE NOX, VOC AND CO EMISSIONS

CHANGES RESULTING FROM AN OXYGEN CONTENT WAIVER

A. Background

RFG, in order to comply with statutory and regulatory requirements, must meet

certain emissions performance and content standards. The emission performance

standards are specified as percent reductions in NOx, VOC and toxics emissions

relative to emissions with a statutory baseline gasoline having properties representative

of 1990 gasoline. These reductions are calculated by the Complex Model, which

estimates the emissions that 1990 technology vehicles would achieve when using both

the statutory baseline gasoline and any RFG formulation that is being evaluated. The

Complex Model calculates a percent reduction between the baseline gasoline and the

RFG at issue. (The properties which are inputs to the Complex Model have previously

been identified in a footnote.) RFG is also subject to oxygen and benzene content

standards. It must contain, on average, at least 2.1 weight percent oxygen and no more

than 0.95 volume percent benzene. In addition to the requirements imposed by the

RFG standards, both RFG and conventional gasoline (CG) are also affected by the

Mobile Source Air Toxics (MSAT) regulations. These regulations cap Complex Model

toxics emissions at their 1998-2000 levels on a refinery-specific basis.17 The Tier 2

gasoline sulfur requirements, when fully implemented, will require an average sulfur

level of 30 ppm or less in both RFG and CG.18 

RFG producers must meet these emission-related regulatory constraints, and

also must supply RFG and CG that meets octane and other driveability-related

requirements. Refiners attempt to produce gasoline and other products in the most

economically advantageous manner, subject to these constraints. The manner in which

a given refinery meets this objective depends on the configuration of the refinery, the

cost and availability of various blending components (e.g. MTBE, ethanol, and alkylate

which have good octane characteristics), and other technical and economic factors. 

Consequently:
15

• RFG emission performance and content standards alone do not determine

RFG’s composition. Other factors may provide additional constraints on certain

emission-related properties.

• RFG composition without a waiver is not uniform across refiners and refineries. 

Complex Model emission performance varies and much RFG overcomplies,

particularly with the NOx and toxics standards. Emissions performance for New

York’s RFG cannot be fully evaluated without estimates of all the relevant fuel

properties which are inputs to the Complex Model.

• The same factors that lead to variety in RFG composition and emissions

performance without a waiver would lead to variety in RFG composition and

emissions performance with a waiver.

• Even though RFG must meet the same Complex Model performance standards

with or without an oxygen waiver, the actual emissions performance may be

different with and without a waiver because the composition of the fuel is likely be

different with and without a waiver. 

B. Emissions Models

Emission performance, as measured by the Complex Model, is a function of

several fuel parameters. The relationship between emissions and gasoline properties

was determined by statistical regression analysis, using several thousand vehicle

emission tests from a number of different studies. Development of the Complex Model,

or any comparable model, such as California’s Predictive Model, requires a number of

decisions, some of which are subjective. Additionally, there are choices in the statistical

techniques that can be used to develop these models. Thus, different models, showing

different relationships between fuel properties and emissions for the same pollutant, can

reasonably result from the same data set. 

EPA developed updated models for NOx and exhaust VOC in order to evaluate

California’s RFG oxygen content waiver request, using data which California used to

develop its Predictive Model. Much of these data were also used to develop EPA’s

Complex Model. These alternative models could be applied to a New York waiver

analysis. While these EPA models differ from the Complex Model, particularly with

respect to the relationship of NOx and oxygen, these models require the same basic

fuel property information as inputs.

In order to evaluate the effect of a change in fuel properties on vehicle emissions,

it is common practice to separate the vehicle fleet into several technology groups. It is

widely believed, and supporting data indicate, that different technology groups respond

differently to fuel property or composition changes. In the California waiver evaluation,

vehicles were divided into three technology groups: older technology vehicles (pre-1986
19 While the assumption regarding no effect certainly does not apply to the relationship

between gasoline sulfur content and NOx performance for these newer Tech 5 vehicles,

in its California waiver analysis EPA was comparing waiver and non-waiver fuel

formulations which had very small differences in sulfur content. Thus, the assumption that

the sulfur content had no effect on “Tech 5" emissions introduced little or no error in that

analysis. 

16

model years), mid-age technology vehicles (model years 1986 through 1995) and newer

vehicles (model year 1996+). These older, mid-age, and newer technology vehicles

were referred to as Tech 3, Tech 4, and Tech 5 vehicles respectively. 

EPA’s alternative NOx and exhaust VOC models, like the Complex Model, are

designed to predict emissions from only a portion of the gasoline mobile source fleet. In

its California waiver analysis, the alternative NOx and exhaust VOC models which were

developed represented the Tech 4 portion of California’s light duty vehicle fleet. Based

on California’s EMFAC7G emission model, Tech 4 vehicles are expected to be the

second largest contributor of the three tech groups to California’s NOx emission

inventory and the largest to its exhaust VOC inventory in 2005. (While the Tech 5

vehicles may have the largest contribution of these three tech groups to the NOx

inventory, there were insufficient data to produce Tech 5 fuel effects emission models

comparable to the Tech 4 models, and engineering reasons to assume that Tech 5

vehicles may not be substantially affected by certain fuel parameter changes).

EPA assumed in the California waiver analysis that newer “Tech 5" vehicles

(model years 1996+) would not respond to changes in oxygen content or other fuel

parameter changes. EPA assumed, as does DEC, that fuel control systems in modern

fuel injected vehicles will compensate for the additional oxygen in gasoline.19

EPA used the “Tech 3" model portion of California’s phase 3 predictive model

representing model year 1981-85 technology, to estimate emissions changes that would

occur in older vehicles. EPA also had emission weighting factors, which were part of

California’s phase 3 predictive model and which estimated the relative contribution to

emissions in year 2005 of these three technology groups. This allowed EPA to combine

separate percent change emission estimates for each of these technology groups into a

single percent change estimate, and apply this percent change to an on-road gasoline

NOx and exhaust VOC emission inventory (in tons per day). This allowed EPA to

estimate overall on-road gasoline NOx and exhaust VOC no-waiver to waiver emission

differences in tons per day. 

EPA believes that an approach utilizing these models, with weighting factors

appropriate for New York, could be used by New York to perform the appropriate

emissions modeling for on-road vehicles in a waiver application.

In its analysis of the California waiver, EPA assumed that changes in emissions

from off-highway or non-road engines would be a function of oxygen content only, using
20 EPA Docket A-2000-10, Docket Number II-B-2.

21 California Air Resources Board (CARB) Staff Report: Initial Statement of Reasons;

Proposed California Phase 3 Reformulated Gasoline Regulations; released October 22,

1999.

17

factors (in percent change in emissions per weight percent of fuel oxygen added)

published in EPA Report No. NR-003, as the basis for its estimate of percent changes in

non-road emissions. Barring new information, it would be reasonable to apply these

same non-road factors in a New York analysis. 

 In its California analysis, EPA had emission inventory information for both onroad and non-road mobile sources. Thus, knowing oxygen content and other fuel

properties, and oxygenated/non-oxygenated market share for each waiver case, EPA

was able to estimate the percent difference in emissions between waiver and nonwaiver scenarios, apply this difference to the inventory to estimate a tons/day difference

and combine the on-road and non-road changes. 

For the reasons described in EPA’s California waiver analysis20, EPA assumes

that carbon monoxide emissions would be primarily affected by fuel oxygen content,

with CO emissions increasing as oxygen content decreases. For California, EPA

modeled on-road CO changes using “percent reduction per weight percent oxygen

increase factors” published in a California Air Resources board staff report.21 EPA used

factors from NR-003, cited earlier, to model off-road CO changes. The on-road percent

changes may be somewhat California-specific, since they were derived from California’s

EMFAC emission factors model. It is probably more appropriate to quantify the CO

emission changes in New York using the Mobile model. 

In summary,

• There are models which may be superior to the Complex Model for evaluation of

on-road vehicle emissions differences in New York with and without an

oxygenate waiver

• These alternative models require essentially the same fuel property information

as the Complex Model, and emission performance for New York’s RFG cannot

be evaluated using these models without estimates of all the fuel property inputs.

• It is reasonable to estimate off-road exhaust emission and on-road CO changes 

from oxygen changes alone and the methods to estimate these emission

changes could (if the requisite information were available) be used in evaluating

a waiver request in New York.
22 RFG surveys are conducted each year by the RFG Survey Association, an association of

refiners, importers and oxygenate blenders. Gasoline samples are collected at retail

stations in RFG covered areas, under a survey plan which EPA approves, and analyzed

for emission-related properties. Independent contractors perform the sample collection

and analysis. These surveys are required by 40 CFR 80.67, for suppliers who choose to

meet RFG standards on an average basis, rather than on a "per gallon" basis. These

surveys are intended to ensure that the RFG supplied to each covered area meets

standards. Specific requirements pertaining to these surveys can be found in 40 CFR

80.68. 

23 EPA has published average property information from RFG surveys through 2003. 

Although 2004 averages have not been published, EPA would have provided data from

2004 surveys to New York DEC as soon as it was available, had it been requested. 

Ozone-season RFG surveys in NY were conducted between June and late August. EPA

receives data approximately 30 days after each survey is completed and received all

ozone season survey data for NY prior to October, 2004.

18

C. RFG Properties and Composition

Knowledge of the likely formulation of RFG in New York with and without an

oxygen content waiver is critical to EPA’s evaluation of whether or not the oxygen

content mandate interfere’s with attainment of the ozone NAAQS. Because this

information has not been provided, EPA is not able to conclude what effect a waiver

would have on vehicle emissions in the NY RFG area. Some information exists

regarding the composition and properties of ethanol-oxygenated RFG 22 supplied to

New York during the ozone season subsequent to New York’s MTBE ban. This RFG

does not, on average, meet the ultimate 30 ppm sulfur requirement which the Tier 2

gasoline sulfur regulations will impose on both conventional and reformulated gasoline,

but reflects transitional sulfur requirements which become more stringent over a multiyear period. Even though these data do not represent full implementation of the Tier 2

sulfur requirement, they are likely to be somewhat informative of the composition of the

RFG that will be supplied to New York in the future in the absence of an oxygen content

waiver.23 However, these data do not predict the composition and properties of the

RFG that would be supplied to New York if a waiver were granted. Consequently, this

information, by itself, is insufficient to evaluate the impact of an oxygen content waiver.

New York’s submissions provide no source of real world data or predicted data

that is informative of the composition of the RFG that would be supplied to New York if

EPA waived the oxygen content requirement. In its waiver submission, California relied

on refinery modeling studies to predict the properties of California Phase 3 RFG

(CaRFG3) and, similarly, EPA relied on expansions of these same refinery modeling

studies to evaluate California’s submission. These studies predicted the properties of

the CaRFG3 that would be produced if an oxygen content waiver were granted, as well

as the properties of the oxygenated CaRFG3 that would be produced without a waiver. 

This modeling was conducted on those refineries supplying RFG to California, so is
24 In fact, refinery modelers typically use completely different models to estimate the

composition of gasoline produced for the New York area versus gasoline produced for the

California market.

25 The modeling which EPA commissioned for the California waiver analysis represented the

characteristics of the California refinery system. Additionally, the modeling required that

California Phase 3 RFG meet California standards for NOx and hydrocarbons based on

California’s Phase 3 predictive model, rather than the Complex Model. Thus, the RFG

modeled for the California waiver analysis was required to meet a much more stringent

NOx standard than the Federal standard. Additionally, since the predictive model, unlike

the Complex Model, indicates that NOx emissions will increase as oxygen content

increases, California’s NOx performance requirements impose a practical limit on weight

percentage of oxygen that can be used in California blends. Consequently, EPA has little

confidence that the forecasts of emission-related fuel parameters which these models

produced would be applicable to New York. 

26 The NESCAUM report submitted as enclosure B of NY’s January 6, 2003 submission

states on page 9, vol.2 “If the oxygen requirement were waived or lifted, it is highly likely

that some amount of ethanol would still be blended into RFG...”

19

California-specific.24 Furthermore, California reformulated gasoline standards, which

are applicable to RFG sold in federal RFG areas in California, differ from federal RFG

standards. Thus, the predictions of the California fuel properties from this modeling are

not applicable to the analysis of the New York waiver since different modeling

constraints would be applied for the California case versus the New York case. For

example, modeling indicated that it was infeasible for California refiners to make RFG

oxygenated at 10% ethanol, while New York is likely to receive 10% ethanol during the

ozone season.25 The California modeling does predict that substantial amounts of

ethanol-oxygenated gasoline would be used in California, even with a waiver of the

federal RFG oxygen content requirement. Although the California analysis is certainly

not directly applicable to New York, the expected use of ethanol in California

demonstrates that, lacking information to the contrary, EPA cannot assume that ethanol

will not be used in New York in a waiver situation. Ethanol may be used to make up, in

part, for the volume and octane which MTBE provided even if EPA waived the oxygen

content requirement. Other studies support such a conclusion.26
27 Although oxygen increases taken alone (i.e., all other properties being equal) directionally

increase NOx emissions in EPA’s alternative models for Tech 4 vehicles, real world

situations clearly show that other RFG properties can and do change the magnitude and

even the direction of this change. In EPA’s evaluation of California’s waiver request using

the alternative models, NOx emissions clearly go down where average oxygen content of

the gasoline pool is lower (i.e., all of the waiver scenarios). However, in other real world

situations fuels can exhibit better NOx performance even with higher oxygen content due

to differences in other properties that affect NOx emissions. To further illustrate this point,

EPA has examined “real world” VOC-controlled RFG survey data collected during the

2003 ozone season and computed two sets of average fuel properties, one from an RFG

area with lower oxygen content and one from an area with higher oxygen content. EPA

utilized averages from surveys conducted in the New York-New Jersey-Long IslandConnecticut area to represent the lower oxygen content RFG, and averages from

Louisville, Kentucky surveys to represent the higher oxygen content RFG. EPA computed

the NOx performance for these two “average fuels” using EPA’s alternative NOx models. 

20

V. EMISSIONS-RELATED CONCLUSIONS BASED ON NEW YORK’S

SUBMISSION

A. Effect of a waiver on NOx emissions based on New York’s submission

1. Multiple gasoline properties affect NOx emissions

With regard to DEC’s comments regarding the complex Model, EPA does agree

that the Complex Model may over-estimate the NOx emission performance of certain 10

v% (about 3.5 wt% oxygen) ethanol-oxygenated RFG blends, because the Complex

Model does not show a NOx increase with increasing oxygen. According to EPA’s

models developed during the California waiver analysis and readily available to NY

DEC, all other properties being equal, as oxygen content increases, NOx emissions will

also increase for Tech 4 vehicles. Thus, if two RFG blends with different oxygen

content were formulated to have the exact same Complex Model NOx performance

(e.g. 6.8 percent reduction from 1990 baseline, the averaged standard), EPA would

suspect that the “true” NOx performance of the blend with the higher oxygen content

would be worse than that of the blend with the lower oxygen content. The problem with

this simplistic argument is that there are many properties and components of RFG other

than oxygen content which would likely be different in a waiver versus no-waiver

scenario, and these other properties and components also affect NOx emissions. (This

is discussed in the previous section of this TSD.) Thus, neither the magnitude nor

direction of a NOx change can be predicted using the data submitted by DEC since the

argument above is based only on oxygen content. 27
The NOx performance of the Louisville, KY “average fuel” is better than that of the New

York “average fuel” based on the EPA alternative model, even though the oxygen content

of the Louisville “average fuel” was higher. (See Docket OAR-2003-0004 Document II-B1.)

21

2. NOx emissions from on-road vehicles with and without a waiver.

 Given property estimates for New York’s “waiver” and “no-waiver” gasolines, a

complete waiver submission would presumably use EPA’s alternative “Tech 4" NOx

models to estimate the emissions change for a portion of the on-road fleet, since these

models were developed with data that are not California-specific. As explained earlier,

the information which DEC has submitted is insufficient to even determine the expected

direction of the “Tech 4" “no waiver” to “waiver” NOx emission change.

An assumption similar to that made for the California analysis, i.e., that the “no

waiver” to “waiver” fuel property differences would have no effect on exhaust emissions

in “Tech 5" vehicles, would likely be appropriate for NY as long as there was little

difference in the sulfur content of the “no waiver” and “waiver” fuels. While this is

somewhat uncertain prior to the implementation of the 30 ppm Tier 2 standard, this

should be the case with that standard in place. Consequently, it would likely be

appropriate to assume that “Tech 5" “no waiver” to “waiver” emission differences would

be zero. 

It would probably be adequate to use the “Tech 3" NOx model portion of

California’s phase 3 predictive model to estimate NOx emission changes for older

vehicles. This model, although it was created by California to represent a portion of

their fleet, was not based solely on California vehicles. This model requires the same

fuel parameter inputs as the alternative “Tech 4" NOx models which EPA developed.

Thus, it cannot be used to determine the probable direction of the NOx emission change

without estimates of New York’s “no waiver” and “waiver” RFG parameters. 

EPA applied California-specific emission weighting factors for Tech 3, 4 and 5

vehicles in its California analysis. They represent the California fleet in 2005 and were

estimated using a California-specific emission factors model. Weighting factors more

applicable to the federal fleet and/or to the New York fleet could be developed with

EPA’s Mobile model. However, DEC did not submit the fuel parameter information to

calculate the Tech 3 or Tech 4 emission changes, nor did it develop weighting factors

for the various Tech groups. Therefore, it is not possible, given the data submitted, to

draw any reasonable conclusions about the magnitude or the direction of NOx

emissions changes in on-road vehicles for the New York waiver/no-waiver comparison.
28 Although without the appropriate analysis, it cannot be said with any certainty that the

waiver would result in the production of non-oxygenated RFG, at least one refiner has

strongly supported granting New York’s request for a waiver. The letter of support from

Tosco Corporation enclosed with New York’s January 6, 2003 submission clearly

indicates that less oxygen would be utilized in New York RFG if a waiver were granted. 

One would presume that support for a waiver from the refining community would indicate

that at least some refiners would blend RFG without oxygen or the waiver would have no

effect on RFG production.

29 “As-blended” RVP refers to the RVP resulting from blending at a refinery or terminal. It is

distinct from the RVP that may exist in commingled fuel in a vehicle fuel tank.

22

3. NOx emissions from non-road vehicles with and without a waiver 

EPA assumes that granting an oxygen content waiver would result in some

decrease in the average oxygen content of New York’s RFG.28 In that case, there

would be some percent decrease in non-road NOx emissions with an oxygen content

waiver. However, EPA cannot estimate how much non-oxygenated RFG would be used

if a waiver were granted in New York. Consequently, EPA can only qualitatively

estimate a directional decrease in NOx for non-road vehicles and engines with a waiver. 

DEC has not submitted any NOx emission inventory information as part of its

waiver request. While the non-road percent change NOx factors are large, EPA

assumes that the non-road gasoline NOx emissions inventory for New York is small

compared to the on-road gasoline NOx emissions inventory. Consequently, even if

EPA concludes that non-road gasoline NOx emissions will be lower with a waiver, EPA

cannot determine with confidence, based only on a qualitative assessment, whether

total mobile source gasoline NOx emissions would be lower with or without a waiver.

B. Effect of a waiver on VOC emissions based on New York’s submission

Evaluating the potential impact of ethanol-oxygenated gasoline on NOx

emissions between a waiver and no-waiver scenario only calls for considering changes

in exhaust emissions. Analysis of VOC impacts is considerably more complex. In

addition to the changes in on-road and non-road exhaust emissions, one must also

consider evaporative VOC emission changes that may occur as a result of “as-blended”

RVP differences between various gasoline formulations. 29 There are also other

emission effects that may occur as a result of ethanol use. Commingling of ethanol and

non-ethanol gasolines in vehicle fuel tanks causes increases in RVP which can result in

higher evaporative VOC emissions. Additionally, use of ethanol-oxygenated gasoline is

believed to increase VOC permeation emissions.
30 While for certain discussions, it may be useful to make a distinction between VOC

emissions and HC emissions, for purposes of the discussion here, there is no difference

between references to VOC and HC emissions. Generally speaking, we use the term HC

as the appropriate convention when referring to emissions models.

23

1. VOC on-road and non-road exhaust emissions

As previously noted, for its California waiver analysis EPA developed alternative 

exhaust hydrocarbon models, estimating changes in exhaust hydrocarbon emissions as

a function of various fuel parameters. For Tech 4 vehicles (Model Year 1986-1995),

these models predict that as oxygen content increases from zero, with other

parameters constant, exhaust hydrocarbon (HC) will first decrease and then increase.30

According to these different models, therefore, decreasing oxygen content from a 3.5%

“no waiver” level, in the absence of other parameter changes, could either reduce or

increase exhaust HC emissions from Tech 4 vehicles, depending on the “waiver”

oxygen content. However, these HC models are a function of several parameters, i.e.,

the same parameters that are inputs to the alternative NOx models identified earlier. As

discussed and demonstrated earlier with respect to NOx, knowing only that oxygen

content is likely to decrease with a waiver, and even knowing the pool average oxygen

content with a waiver, does not provide enough information to determine the net effect

on emissions, because changes in other parameters could offset emission changes due

to oxygen. Consequently, without further information, EPA cannot predict even the

direction of the exhaust VOC emission differences between “no waiver” and “waiver”

RFG in Tech 4 vehicles. 

EPA believes that the assumptions discussed earlier for Tech 3 and Tech 5 NOx

emissions are valid for Tech 3 and Tech 5 exhaust HC as well; that exhaust HC will

probably not be substantially affected by oxygen content or other parameters for Tech 5

vehicles, and the “Tech 3" exhaust HC portion of California’s Phase 3 Predictive Model

may be the best available model to predict fuel-related exhaust HC changes in older

vehicles. However, this Tech 3 model requires the same fuel parameter inputs as the

alternative “Tech 4" HC models which EPA developed.

In its California analysis, EPA used Tech 3, Tech 4 and Tech 5 exhaust HC

weighting factors. As with NOx, these weighting factors were derived with California’s

mobile source emissions model, and incorporated into the predictive model. The

emission weighting factors which were applied in the California analysis are Californiaspecific; they represent the California fleet in 2005 and were estimated using a

California-specific emission factors model. Weighting factors more applicable to the

federal fleet and/or to the New York fleet could be developed with EPA’s Mobile model. 

However, DEC did not submit the fuel parameter information to calculate the Tech 3 or

Tech 4 emission changes nor did it develop weighting factors for the various Tech

groups. Therefore, it is not possible, given the data submitted to make conclusions

about either the magnitude or the direction of exhaust VOC emissions from on-road

vehicles for the waiver/no-waiver comparison.
31 Available data and models do not accommodate consideration of additional fuel

properties.

32 That is, RVP is the only fuel parameter input assumed to affect evaporative emissions. 

The evaporative emission estimates produced by EPA’s Mobile model are also affected

by ambient temperature inputs and other area-specific factors. In its California waiver

analysis, EPA used a formula, derived with California’s EMFAC7G model, to estimate the

VOC emission differences resulting from RVP differences. It would be appropriate to use

a non-California model such as the Mobile model or the Complex model to model any

relevant RVP-related “no waiver” to “waiver” evaporative emissions changes in New York.

33 See 40 CFR 80.41(e) and (f).

24

As we did in the California analysis, EPA assumes that non-road exhaust VOC

emission changes are largely a function of oxygen content, and that exhaust VOC

emissions would increase as oxygen content decreases.31 Thus EPA would expect an

increase in non-road exhaust VOC emissions with a waiver. It would probably be

appropriate to model these emissions for New York using the factors which EPA used in

the California analysis. These factors are incorporated into EPA’s NONROAD2004

model, and this model could be used directly to estimate nonroad exhaust emission

levels, in tons per day, for the RFG areas in New York in the absence of a waiver. 

However, since DEC has not addressed the issue of non-oxygenated market share with

a waiver and has not provided an estimate of pool average oxygen content with a

waiver, it is not possible to estimate the magnitude of the “no waiver” to “waiver”

emission change in non-road VOC exhaust emissions.

2. Evaporative VOC emissions due to RVP increases

Non-exhaust emissions of VOC (except permeation) are modeled as a function

of RVP only.32 In other words, if estimates are available of RVP changes between the

waiver and non-waiver scenarios, existing models can be used to predict nonpermeation changes in evaporative emissions of VOC. New York has offered some

estimates of RVP changes of MTBE-containing RFG and ethanol-containing RFG. As

described earlier, this comparison is not relevant to the technical question before EPA -

whether use of ethanol-containing RFG without a waiver leads to more ozone formation

than use of RFG with an oxygen waiver. There are also other problems with New

York’s assumptions.

The RVP level in ozone season RFG is tightly constrained by the need to comply

with Complex Model VOC performance standards.33 Specifically, DEC assumed that

RFG in the New York RFG area would increase in RVP by 0.3 psi if a waiver is not

granted. They attributed such increase in RVP to a regulation that EPA promulgated on

July 17, 2001 that allows a more lenient VOC performance standard (equivalent to an

increase in RVP by 0.3 psi) for RFG containing 10 volume percent ethanol. However,

this regulation applies only in Chicago and Milwaukee, and in the rulemaking EPA noted
34 See 66 FR 37157 and 40 CFR 80.40(c)(3).

35 New York does not allow use of the 1.0 psi RVP allowance for ethanol-containing

gasoline but can provide a waiver to blenders to use such an allowance.

25

that this limitation was needed based on the area-specific modeling used to support the

rule.34 DEC’s assumptions regarding the RVP increase and associated VOC increases

are therefore in error. It is not reasonable for DEC to assume that EPA would conduct a

future rulemaking to establish a similar adjusted VOC standard for New York RFG

blended at 10 volume percent ethanol, without considering the potential impact on New

York’s ozone air quality.

DEC also included estimates of a VOC emission increase predicted to occur

either statewide or just outside of RFG areas if New York granted a 1.0 psi increase in

the RVP volatility standard for ethanol-containing gasoline were granted by New York.35

There are several problems with DEC’s analysis. First, DEC did not explain how the

federal oxygen content requirement for RFG relates to the use of ethanol in the

conventional gasoline used in non-RFG areas. Thus, EPA has no basis for evaluating

New York’s apparent assumption that, without a waiver, ethanol will be blended into

conventional gasoline in such a way as to affect attainment of the ozone NAAQS. 

Furthermore, New York itself would have to allow such a volatility waiver for

conventional gasoline. Finally, even if New York allowed the RVP of conventional

gasoline to increase, such an allowance would clearly not be applicable to RFG since

RFG is subject to other completely separate and more stringent VOC standards. 

Consequently, there are flaws in New York’s analysis of RVP levels to be expected in

the non-waiver scenario in both CG and RFG areas in the State. Without a more

detailed explanation of New York’s argument, EPA cannot come to any conclusions

about how a 1.0 psi change in conventional gasoline might occur, how it might impact

RFG properties in the New York RFG area, and, finally, how such changes might impact

attainment of the ozone NAAQS.

As described earlier, an RVP boost and associated increase in VOC emissions

can occur within the gas tanks of cars when fuel containing ethanol is commingled with

fuel that does not contain ethanol. New York asserts that commingling will increase

when ethanol is substituted for MTBE as an oxygenate in RFG. Presumably New York

is referring to the commingling of ethanol-oxygenated RFG purchased within the New

York RFG area with non-ethanol gasolines purchased outside of the New York RFG

area. NY does not attempt to quantify this effect. While this may occur in a no-waiver

scenario, New York does not address the central question of how much ethanoloxygenated and non-oxygenated RFG would exist within the NY RFG area if an oxygen

content waiver were granted. 

EPA believes that the maximum adverse commingling impact occurs when

ethanol and non-ethanol gasolines are sold in significant quantities in the same
36 "Emission Impacts of Fuels to Accommodate the NY State Oxy-waiver Request and

MTBE Ban" page 6.

26

geographic area (e.g. the New York State portion of the New York City CMSA). In its

California waiver analysis, EPA concluded that this condition could exist if California

were granted an oxygen content waiver, because the refinery modeling indicated that

some refiners would blend ethanol in RFG even if the waiver was granted, while other

refiners would not. As noted previously, DEC has not addressed the issue of possible

use of ethanol in New York RFG if a waiver were granted. EPA believes that some

refiners supplying RFG to New York would blend ethanol into RFG even if a waiver was

granted, due to the octane ethanol provides and to make up for the lost gasoline volume

from MTBE resulting from New York’s MTBE ban. As discussed previously, there is no

basis for EPA to assume that under a waiver, all RFG will be free of ethanol. 

Consequently, the maximum adverse commingling impact could occur in New York if

EPA grants an oxygen content waiver, leading to corresponding increases in RVP and

evaporative VOC emissions. This maximum adverse commingling impact condition

would not exist in New York without a waiver, since without a waiver only ethanoloxygenated RFG would be sold within the New York portion of New York’s RFG areas.

In summary, while some commingling could occur in the non-waiver scenario as

cars travel back and forth from New York’s RFG areas (where ethanol is used) to other

areas (where it may or may not be used), such commingling would likely be much less

prevalent than would be the case with an oxygen waiver. In the absence of modeling

showing how much ethanol will be used in New York’s RFG if the oxygen content

requirement were removed, EPA believes it most likely that commingling will be more

prevalent with a waiver than without a waiver. It follows that VOC evaporative

emissions resulting from commingling would likely be greater if a waiver were granted

than if it were not, however without further explanation it is not possible to estimate the

magnitude of this impact. 

3. Evaporative VOC emissions due to permeation 

EPA assumes that increased ethanol use would cause some increase in

permeation-related VOC emissions. DEC has provided a quantitative estimate of the

increase in emissions that could occur (6.1 tons per day over a fleet of five million

vehicles) compared to levels prior to an MTBE ban. While it provided some explanation

of the basis for this estimate, it did not specify in its January 6, 2003 submission what

this fleet represented. An enclosure to DEC’s December, 2003 submission identified 

the 6.1 tons per day estimated increase as occurring in the NYCMA ozone

nonattainment area as a result of conversion from MTBE-RFG to ethanol–RFG.36 Since

ethanol may still be used in some significant quantities even if a waiver were granted,

this estimate would lead to overstating the difference in permeation VOC emissions

between the “no waiver” and “waiver” cases. EPA assumes that the “no waiver” to
27

“waiver” difference in permeation effect would be dependent on the amount of ethanol

used if a waiver were granted.

The change in permeation emissions between the non-waiver and waiver

conditions depends on the extent to which ethanol RFG would be used were a waiver

granted, and DEC has not provided estimates of ethanol use in RFG with a waiver. 

Additionally, estimates of permeation emission changes would have to be combined

with estimates of exhaust and other evaporative VOC emission changes in order to

estimate the total “no waiver” to “waiver” VOC change. DEC has not provided such

estimates or the underlying fuel property information needed to make such estimates. 

Thus, even with the best available quantitative estimate of permeation emission

differences between ethanol-oxygenated and non-ethanol gasoline, EPA could still not

determine the net effect of the oxygen waiver on VOC emissions with the information

submitted by DEC. In summary, EPA believes that permeation-related VOC emissions

would likely be less with a waiver, because we assume that less ethanol will be used

with a waiver than without. However, without further information it is not possible to

estimate the magnitude of this impact.

C. Effect of a waiver on CO emissions

DEC did not address emissions of CO, although increases in CO can contribute

to increases in ozone Because of the lack of information on ethanol market share

should a waiver be granted, there is insufficient information for a quantitative estimate of

“waiver” to “no waiver” CO emission changes for New York, since EPA cannot

determine the average oxygen content for the “no waiver” case or cases from the

available information. Directionally, EPA assumes that average oxygen content will

decrease with a waiver. CO emissions should increase for Tech 3 , Tech 4 and nonroad, and remain the same for Tech 5. While EPA can estimate this directional impact,

without further information it is not possible to estimate the magnitude of this impact.

D. Ethanol transport-related emissions

While there will be emissions resulting from the transport of ethanol to terminals,

the difference in emissions would depend, in part, on the amount of ethanol used in

New York with and without a waiver. DEC has not provided that information. 

Therefore, EPA concludes that without further information it is not possible to estimate

the magnitude of this impact. In any case, Enclosure I of DEC’s January, 2003

submission suggests that the relative contribution of these emissions would be small. 
37 The table in Appendix A summarizes EPA’s qualitative consideration of New York’s waiver

request. 

28

VI. CONCLUSIONS OF EPA’S ANALYSIS OF DEC’S SUBMISSION

The information that DEC has provided fails to clearly demonstrate what effect a

waiver would have an on ozone levels in New York. This is because: 1) there are three

pollutants whose emission rates could be altered by a waiver, (NOx, VOC and CO) and

all three affect ozone formation to varying degrees, 2) the lack of information on fuel

qualities with and without a waiver and the lack of other relevant and necessary

information precludes even a directional estimate of the impact of a waiver on NOx and

VOC emissions, 3) the best estimate of the net impact of a waiver on CO emissions is

that CO emissions would be greater with a waiver than without, but the difference

cannot be quantified and 4) no analysis has been provided or performed, and the

information before the agency does not allow an analysis to be performed, on the

combined effect of these emissions changes on ozone. EPA concludes that there has

been no clear demonstration as to the effect a waiver would have on ozone. 37
38 If ethanol is used in NY’s RFG to a significant extent with a waiver, then EPA expects

commingling VOC emissions to increase. If ethanol is not used extensively with a waiver,

then the direction of this VOC change is uncertain. EPA believes that significant ethanol

use with a waiver is likely. 

29

APPENDIX A: SUMMARY OF EPA’S ANALYSIS OF DEC’S SUBMISSION

The following table summarizes EPA’s assessment of the directional change in “no

waiver” to “waiver” emissions for each on-road vehicle technology group, and for nonroad gasoline vehicles and engines. “I” indicates an increase, “D” a decrease, “0" little

or no change, and “?” means insufficient information to determine.

NOx Exhaust

VOC

as blended

evap VOC

commingling

VOC 38

Permeation

VOC

CO

Tech 3

on-road

? ? ? I or ? D I

Tech 4

on-road

? ? ? I or ? D I

Tech 5

on-road

0 0 ? I or ? D 0

non-road D I ? I or ? D I
30

APPENDIX B: EPA’S RESPONSE TO DEC’S REASONS FOR NOT PROVIDING

INFORMATION THAT EPA REQUESTED

DEC provided information in its January 6, 2003 submission to EPA which we

reviewed. We responded in a letter dated April 1, 2003 with comments and questions

on the data submitted, and asked DEC to provide specific types of analyses and

information in order for EPA to evaluate New York’s request for a waiver. DEC

responded to our questions in a letter to EPA dated December 12, 2003 and provided

reasons why it did not provide what we requested and in some cases why DEC felt such

information was not necessary. For those issues not discussed in the Technical

Support Document, we describe here DEC’s responses and . our assessment of those

responses. 

I. DEC failed to provide information on the actual fuels that would likely be

used in the New York RFG area with and without a waiver

DEC states that EPA’s request for refinery modeling goes beyond the scope of

the Clean Air Act as it pertains to waivers of the oxygen requirement in RFG. DEC also

states that the benefits of refinery models are questionable and that the information that

models provide is “of limited applicability” for evaluation of its waiver request. Finally, 

DEC argues that because EPA commissioned its own refinery modeling study when

evaluating California’s request for a waiver, that “it is more reasonable and appropriate

for EPA to perform the modeling, as New York lacks refineries or the authority to collect

specific information on their production plans.” 

A. Requesting refinery modeling is within the scope of the Clean Air Act

In DEC’s December 12, 2003 letter to EPA, DEC states that the refinery

modeling we requested “goes far beyond the scope of the language contained in

section 211 of the Clean Air Act and was clearly not contemplated by Congress when it

drafted section 211(k)(2)(B) of the Act.” We disagree. The Act only allows EPA to grant

a waiver if it determines that compliance with the RFG oxygenate requirement would

prevent or interfere with the attainment by the area of a national primary ambient air

quality standard. As explained in the Decision Document and the main body of this

Technical Support Document, refinery modeling is necessary for EPA to be able to

make a determination one way or another as to whether the oxygen content

requirement prevents or interferes with NAAQS attainment. 
39 Oxygenated Fuels Association, Inc. v George Pataki; U.S. District court, Norther District of

New York filed Nov 24, 2003; pp. 9-13. (This document is filed in docket OAR-2003-

0004, Document II.D.6A.)

40 Filed in docket OAR-2003-0004, Document II.D.1i.

31

B. DEC provides no evidence that refinery models are of limited

applicability with respect to its request for a waiver.

In its assertion that refinery models are questionable and provide information that

is of limited applicability, DEC refers to discussion of refinery modeling in the matter of

Oxygenated Fuels Association (OFA) v. Pataki, a court decision which they provided as

an attachment to their December 12, 2003 letter.39

The referenced document is a court decision in the case brought by OFA against

the State of New York. OFA claimed that New York’s law prohibiting MTBE use in that

state is a violation of the Supremacy Clause of the U.S, Constitution because it

legislates in a field preempted by Congress. DEC points to the discussion of refinery

modeling in this court decision as an example of how the information provided by

refinery models is of limited applicability in DEC’s waiver application. The discussion of

refinery modeling in the referenced document does not provide such an example.

Specifically, the court rejected the evidence presented by an expert refinery

modeler based on “its lack of reliability and credibility.” The expert’s testimony

consisted of the results of running a refinery model comparing MTBE and ethanoloxygenated gasolines. Cross examination disclosed that the expert employed

undisclosed methods in preparing his report and testimony. These methods included

excluding from the expert’s report model results which were unfavorable to OFA, and

using predetermined values for certain of the parameters of gasoline that affect tailpipe

emissions for MTBE-RFG but not using such predetermined values for ethanol-RFG. 

Although the court discredited the expert’s testimony, such action is not evidence that

the results of any and all refinery modeling is of “limited applicability,” as claimed by

New York. The inappropriate withholding of modeling results or limiting variation of the

input parameters does not prove that the models themselves are inappropriate or of

limited applicability when correctly used. This fact is acknowledged in the document

that DEC included in its January 6, 2003 letter requesting a waiver--a chapter entitled

“Background and Strategies for Developing a Northeast States Oxygenate Waiver

Request” excerpted from a report prepared by the Northeast States for Coordinated Air

Use Management (NESCAUM).40 The chapter identifies arguments and data needed

for waiver requests. For each of the various arguments the document identifies for

inclusion in an application for a waiver, refinery modeling is recommended as the initial

step.
41 For example, the industry collects information on gasoline quality in RFG areas under the

survey requirements found at 40 CFR 80.68 and EPA regularly shares and publishes

such information and would be willing to work with New York to provide such information.

42 Available at http://www.arb.ca.gov/regact/carfg3/appo.pdf. 

43 Available at

http://www.energy.ca.gov/mtbe/documents/1999-12-07_PHASE-3_.FINAL.PDF.

44 Available at http://www.epa.gov/otaq/regs/fuels/rfg/r01016.pdf 

32

C. New York’s lack of refineries does not prevent the State from

collecting specific information on refinery production plans

In its December 12, 2003 letter, DEC states that if EPA wishes refinery modeling

to be performed that EPA perform such modeling, because “New York lacks refineries

or the authority to collect specific information on their production plans”. 

Although New York State may not have the authority to collect specific refinery

information, there is a great deal of information regarding the fuel properties of gasoline

delivered to the New York area and to the Northeast generally.41 More importantly,

refinery modeling services would have to be employed in order to predict changes in the

properties of gasoline delivered to New York if a waiver were granted. Such predictions

were made by refinery modeling services for both the state of California in its waiver

request and in EPA's own analysis of those predictions. There are several widely

recognized independent refinery modeling companies that offer such services.

D. EPA’s commissioning of a refinery study to evaluate California’s

request for a waiver does not obligate the Agency to commission

such a study in evaluating DEC’s request 

DEC argues in its December 12, 2003 letter that the precedent for EPA

conducting refinery modeling exists, pointing to EPA’s commissioning a refinery

modeling study for California’s waiver application.

California made available to us the following: 1) refinery modeling conducted by

Math Pro and commissioned by Chevron and Tosco42 ) and 2) refinery modeling

conducted by the California Energy Commission, dated December 7, 1999.43 EPA

discussed these reports and other information with California Air Resources Board

(CARB) in January of 2000. EPA concluded that the refinery modeling that CARB

provided EPA, for reasons discussed in the Technical Support Document44, did not

provide a sufficient basis for evaluation of California’s waiver request. Consequently,

EPA commissioned MathPro to do additional modeling. 
33

When California requested a waiver, it was the first request for a waiver under 

Section 211(k)(2)(B) of the Clean Air Act. As such, there were no analytical precedents 

for either California or EPA were able to follow. CARB diligently attempted to support its

waiver request by providing the refinery modeling that they did to EPA We felt it

appropriate that we arrange to have additional refinery modeling conducted to better

define the technical issues that we felt such analysis should address. 

Therefore, our action with respect to California’s waiver request was predicated

under different circumstances and does not set a precedent for similar action for New

York. Our experience with California’s waiver request has now clarified the kind of

refinery modeling and comparable analyses that are appropriate to support a waiver

request. Information on the kind of modeling and analyses needed was available to New

York before it applied for a waiver, making it appropriate for EPA to expect DEC to

conduct or have conducted such analyses. 

Beyond these considerations, EPA notes that it is DEC, not EPA, that seeks the

waiver. EPA believes it is appropriate to require the petitioner in such circumstances to

provide the information needed for favorable consideration of its request. 

II. DEC failed to respond to our request to provide the expected changes in

emissions that would occur in a waiver and non-waiver scenario, from onroad and non-road sources 

In its initial submission, DEC only attempted to quantify emissions increases of

VOCs If a waiver was not granted, and did not provide quantitative emissions estimates

for CO or NOx for either the waiver or non-waiver scenarios. In our April 1, 2003 letter to

DEC, we asked for clarification and additional information. We requested that DEC

address the emissions (for both on-road and non-road sources) for all pollutants that

have a potential to impact a NAAQS. We requested information relating to VOC

emissions resulting from commingling and permeation effects due to ethanol with and

without a waiver. We asked specific questions about the estimates of VOC increases that

DEC made for the New York RFG area as well as upstate New York. Finally, we asked

for estimates of emission increases due to transport of ethanol to the New York RFG

area.

In its December 12, 2003 letter, DEC responded that it had considered EPA’s

request for emissions modeling and that “such analyses cannot be reasonably completed

with the approved tools available - specifically the Mobile and Nonroad models.” DEC

states that the emissions modeling EPA requested cannot be completed with these

models because the user inputs for the two models are different, and the nonroad model

does not model RFG at all. DEC also states: “The Mobile model does not provide for

differing the oxygenate amounts when modeling RFG, nor does it allow the user to

differentiate between oxygenate types - the very purpose of the requested modeling.” 
45 Filed in docket OAR-2003-0004, Document I.D.g

46 The model is discussed in Section III.A.5 of the Technical Support Document

associated with California’s request for waiver (EPA-420-R-01-016, June 2001), and

which is available at http://www.epa.gov/otaq/regs/fuels/ref/r01016.pdf. 

47 The FUEL PROGRAM command option 4 as a conventional gasoline program with

alternate sulfur levels can be used to provide differing inputs of oxygen. It is designed

to allow users to specify an RFG program with alternate sulfur levels, but it also allows

for varying the other non-sulfur fuel parameters through the FUEL RVP and

OXYGENATED FUELS fuel commands to approximate the non-sulfur effects of RFG. 

These commands allow the user to specify the fuel RVP, the ether and ethanol market

shares, and the oxygen content of the ether and ethanol blends. Thus, if the user

wanted to keep the sulfur defaults, and was interested only in modeling RFG's with

different RVPs and oxygen content, the user would enter the default sulfur values as his

alternate sulfur values. 

34

Regarding permeation emissions, DEC stated that it included a draft paper on permeation

in its original submission. With respect to estimates of VOC due to commingling, DEC

states that such emissions are affected by a wide range of variables “that cannot be

accurately predicted with the tools available.” DEC further argues that a reduction in

ethanol usage resulting from a waiver would directly reduce VOC emissions from

permeation and commingling. Finally, DEC states that the emissions modeling that it

included in its January 6, 2003 submission is accurate for purposes of the waiver

application and enclosed it again in its December 12, 2003 letter45.

A. DEC’s claims that the requested emission modeling cannot be

completed are not valid.

In the attachment to EPA’s April 1, 2003 letter to DEC, we stated that DEC could

use models and methods other than those referenced by DEC in its response to estimate

emission changes resulting from fuel property changes. We specifically mentioned the

model that EPA developed as part of its analysis of California’s request for waiver46, and

stated that consistent with EPA’s approach in its analysis of the California waiver, DEC

may use separate models and methods to estimate fuel-related emission effects in

different segments of the fleet. The referenced document also contains information on

estimating emissions from non-road sources using RFG. 

We disagree with DEC’s assertion that the Mobile model does not allow for

variable amounts of oxygen in the fuel. Mobile does model variable amounts of oxygen in

RFG.47 We provide advice to many states on issues such as this pertaining to the Mobile

model and are willing to do the same for New York. We note that DEC did not contact us

on this issue prior to its December 12, 2003 letter.

We also do not agree with DEC’s assumption that the Mobile model does not allow

the user to differentiate between oxygenate types. Mobile does allow for such

differentiation for the reason that if ethanol is specified and the ethanol market share is
48 Specifically, SAE paper 940765, “In-Use Volatility Impact of Commingling Ethanol and

Non-Ethanol Fuels”, by Peter J. Caffrey and Paul A. Machiele, USEPA, describes a

model developed to estimate commingling effects. Also, Dr. D. M. Rocke, University of

California at Davis, developed a probability model (“UCD model”) to study commingling.

35

not 100 percent, then Mobile slightly increases the RVP depending on market share. 

Although permeation effects are not considered in Mobile, they can be estimated using

other methods.

B. DEC’s reasons for not estimating commingling emissions are not

valid.

DEC asserts that the tools for estimating commingling emissions do not allow for

accurate predictions. We note that the referenced Technical Support Document for

EPA’s response to California’s request for waiver contains information on how

commingling emissions may be estimated.48 The variables that affect commingling

emissions allow for a range of emission changes to be estimated and evaluated as was

done for California. Increases in VOC associated with commingling are a function of the

mix of non-ethanol and ethanol-oxygenated RFG available in a given area. Some amount

of oxygenated RFG would still likely be made and supplied to the New York RFG area

even if a waiver were granted and there would also be some oxygenated RFG used in the 

New York RFG area because of the adjacent areas still using MTBE-blended RFG, or

conventional gasoline. Like most models, the accuracy of a model’s estimations depends

on the accuracy of the information that is used as input to the model. Refinery modeling

or comparable analysis augmented by survey data (to assess consumers “brand loyalty”,

which the commingling model uses to estimate the degree of commingling that could

occur in a given area) would provide estimates of the likely mix of these two types of fuels

that refiners would supply the New York RFG area in a waiver scenario. These estimates

would then be used as inputs to the commingling model which provides a valid method to

assess the potential for emission increases due to commingling. 

C. DEC’s resubmitted emission estimates are in error and do not address

questions raised in our April 1, 2003 letter to them.

DEC’s emission estimates that it resubmitted do not include changes in NOx and

CO emissions with and without a waiver which we asked for in our April 1, 2003 letter. 

With respect to its estimates for VOCs, DEC assumes that all RFG in the New York RFG

area will be non-oxygenated in a waiver scenario. This assumption regarding the

penetration level of non-oxygenated RFG is not supported and, as described in section

IV-C of this TSD, appears likely to be faulty. 
49 See 66 FR 37157 and 40 CFR 80.40(c)(3)

50 Filed in docket OAR-2003-0004, Document II.D.1h.

36

In our April 1, 2003 letter to DEC we raised several questions regarding DEC’s

emission estimates for VOCs. Specifically, DEC assumed that RFG in the New York

RFG area would increase in RVP by 0.3 psi if a waiver is not granted. They attributed

such increase in RVP to a regulation that EPA promulgated on July 17, 2001 that allows a

more lenient VOC performance standard (equivalent to an increase in RVP by 0.3 psi) for

RFG containing 10 volume percent ethanol. Since the regulation applies only in Chicago

and Milwaukee49, DEC’s assumptions regarding the RVP increase and associated VOC

increases are in error. 

DEC has not answered our questions as to why there would be statewide

increases in RVP of either 0.3 or 1.0 psi in conventional gasoline (CG) if a waiver were

not granted. With respect to the prediction of the 1.0 psi increase in RVP in CG, we

asked how the oxygen requirement for RFG (if a waiver were not granted) would result in

a level of 10 volume percent ethanol in all CG in New York State.

DEC has not responded to our request to provide an estimate of the emission

increase associated with transport of ethanol to the New York RFG area, both with and

without a waiver. 

Finally, DEC also has not responded to our question regarding permeation

emissions except to say that information on this topic is limited. We asked for clarification

and explanation regarding information DEC provided in its January 6, 2003 submission. 

Specifically, DEC stated that ethanol as a replacement for MTBE will result in VOC

increases from permeation of 6.1 tons/day based on a derived emission factor applied to

five million vehicles.50 We requested DEC explain what the five million vehicles

represents; i.e., is it total vehicles in the New York RFG area, or in all of New York State? 

If the latter, is it only that portion of vehicles that would use gasoline containing ethanol? 

In summary, DEC asserts that its emissions modeling for VOCs is accurate, but

EPA has identified certain shortcomings in New York’s approach, and has asked several

questions (which DEC has chosen not to answer) that need to be answered for EPA to

ascertain whether or not other shortcomings exist.
51 Letter dated December 3, 2003 from John Peter Suarez, Assistant Administrator of the

Office of Enforcement and Compliance Assistance, to Edward H. Murphy, American

Petroleum Institute.

37

III. EPA’s issuance of an enforcement discretion letter does not preclude the

granting of an oxygenate waiver

In its December 12, 2003 letter, DEC references an enforcement discretion letter

from EPA to the American Petroleum Institute.51 DEC asserts that EPA through this

enforcement discretion “has enacted a requirement for fuels containing 10 percent

ethanol” and that such action precludes the granting of an oxygen content waiver.

The referenced letter does not constitute a requirement that fuels in the New York

RFG Area contain 10 percent ethanol. In fact, the enforcement discretion letter does not

preclude the use by refiners of oxygenates other than ethanol or, if EPA were to grant

New York’s waiver request, the delivery of RFG with no oxygenate. The enforcement

discretion letter simply informs parties that receive reformulated gasoline blendstock for

oxygenate blending (RBOB) at terminals and blend 10 volume % ethanol to produce RFG

of a set of circumstances under which their RBOB will be treated as certified under 40

C.F.R. Section 80.69(a)(2). It does not require that all RFG in the New York RFG area

contain any quantity of ethanol, and does not preclude the granting of an oxygen content

waiver.