[Federal Register Volume 59, Number 32 (Wednesday, February 16, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 94-20]
[[Page Unknown]]
[Federal Register: February 16, 1994]
_______________________________________________________________________
Part II
Environmental Protection Agency
_______________________________________________________________________
40 CFR Part 80
Regulation of Fuels and Fuel Additives; Standards for Reformulated and
Conventional Gasoline; Final Rule
ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 80
[AMS-FRL-4817-8]
Regulation of Fuels and Fuel Additives: Standards for
Reformulated and Conventional Gasoline
AGENCY: Environmental Protection Agency.
ACTION: Final rule.
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SUMMARY: Through the amended Clean Air Act of 1990, Congress mandated
that EPA promulgate new regulations requiring that gasoline sold in
certain areas be reformulated to reduce vehicle emissions of toxic and
ozone-forming compounds. This document finalizes the rules for the
certification and enforcement of reformulated gasoline and provisions
for unreformulated or conventional gasoline.
DATES: The regulations for the reformulated gasoline program are
effective on March 18, 1994. The incorporation by reference of certain
publications listed in the regulations is approved by the Director of
the Federal Register as of March 18, 1994. The information collection
requirements contained in 40 CFR part 80 have not been approved by the
Office of Management and Budget (OMB) and are not effective until OMB
has approved them. EPA will publish a document in the Federal Register
following OMB approval of the information collection requirements.
Retail sale of reformulated gasoline will begin on January 1, 1995,
as will the provisions for the ``simple model'' certification, the
anti-dumping program for conventional gasoline, and the associated
enforcement procedures. (For all ensuing sections of this document, the
program's beginning date of January 1, 1995 refers only to the retail
sale of reformulated gasoline.) Certification of reformulated gasoline
by the ``complex model'' and compliance with the Phase II performance
standards, will begin January 1, 1998 and January 1, 2000,
respectively.
ADDRESSES: Materials relevant to this FRM are contained in Public
Dockets A-92-01 and A-92-12, located at room M-1500, Waterside Mall
(ground floor), U.S. Environmental Protection Agency, 401 M Street SW.,
Washington, DC 20460. The docket may be inspected from 8 a.m. until 12
noon and from 1:30 p.m. until 3 p.m. Monday through Friday. A
reasonable fee may be charged by EPA for copying docket materials.
FOR FURTHER INFORMATION CONTACT:
Paul Machiele (reformulated gasoline requirements), U.S. EPA (RDSD-12),
Regulation Development and Support Division, 2565 Plymouth Road, Ann
Arbor, MI 48105, Telephone: (313) 668-4264.
George Lawrence (reformulated gasoline and anti-dumping enforcement
requirements), U.S. EPA (6406J), Field Operations and Support Division,
501 3rd Street, Washington, DC 20005, Telephone: (202) 233-9307.
SUPPLEMENTARY INFORMATION: Today's final rule is preceded by four
previous notices: an initial notice proposing standards for
reformulated and conventional gasoline (NPRM) published on July 9, 1991
(56 FR 31176), a supplemental notice (SNPRM) published on April 16,
1992 (57 FR 13416), an additional NPRM published on February 26, 1993
(58 FR 11722), and a notice of correction for Phase II standards
published on April 1, 1993 (58 FR 17175). Insofar as the rules
finalized today mirror the proposed standards, those previous documents
may be referred to.
Today's preamble explains the basis and purpose of the final rule,
focusing on issues that have been revised since the publication of the
correction notice for the Phase II performance standards (58 FR 17175).
Support documents, including the Regulatory Impact Analysis (RIA), are
available in Public Docket No. A-92-12.
To Request Copies of This Final Rule Contact: Delores Frank, U.S.
EPA (RDSD-12), Regulation Development and Support Division, 2565
Plymouth Road, Ann Arbor, MI 48105, Telephone: (313) 668-4295.
Copies of the preamble, the Final Regulatory Impact Analysis (RIA),
the Responses to Comments on Enforcement Provisions (RCEP), the complex
model, the simple model and the regulations for the reformulated
gasoline rulemaking are available on the OAQPS Technology Transfer
Network Bulletin Board System (TTNBBS). The TTNBBS can be accessed with
a dial-in phone line and a high-speed modem (PH# 919-541-5742). The
parity of your modem should be set to none, the data bits to 8, and the
stop bits to 1. Either a 1200, 2400, or 9600 baud modem should be used.
When first signing on, the user will be required to answer some basic
informational questions for registration purposes. After completing the
registration process, proceed through the following series of menus:
(M) OMS
(K) Rulemaking and Reporting
(3) Fuels
(9) Reformulated gasoline
A list of ZIP files will be shown, all of which are related to the
reformulated gasoline rulemaking process. The six documents mentioned
above will be in the form of a ZIP file and can be identified by the
following titles: ``PREAMBLE.ZIP'' (preamble); ``RIAFINAL.ZIP'' (RIA);
``ENFORCE.ZIP'' (RCEP); ``EPAFINAL.ZIP'' (complex model);
``MODFINAL.ZIP'' (simple model); ``REGFINAL.ZIP'' (regulations). To
download these files, type the instructions below and transfer
according to the appropriate software on your computer:
ownload, rotocol, xamine, ew, ist, or to exit: D filename.zip
You will be given a list of transfer protocols from which you must
choose one that matches with the terminal software on your own
computer. Then go into your own software and tell it to receive the
file using the same protocol. Programs and instructions for de-
archiving compressed files can be found via ystems Utilities from
the top menu, under rchivers/de-archivers.
I. Background
The purpose of the reformulated gasoline regulations is to improve
air quality by requiring that gasoline be reformulated to reduce motor
vehicle emissions of toxic and tropospheric ozone-forming compounds, as
prescribed by section 211(k)(1) of the Clean Air Act (CAA or the Act),
as amended. This section of the Act mandates that reformulated gasoline
be sold in the nine largest metropolitan areas with the most severe
summertime ozone levels and other ozone nonattainment areas that opt
into the program. It also prohibits conventional gasoline sold in the
rest of the country from becoming any more polluting than it was in
1990. This requirement ensures that refiners do not ``dump'' fuel
components that are restricted in reformulated gasoline and that cause
environmentally harmful emissions into conventional gasoline.
Section 211(k)(l) directs EPA to issue regulations that, beginning
in 1995, ``require the greatest reduction in emissions of ozone-forming
and toxic air pollutants (``toxics'') achievable through the
reformulation of conventional gasoline, taking into consideration the
cost of achieving such emission reductions, any non air-quality and
other air-quality related health and environmental impacts and energy
requirements.'' The Act mandates certain requirements for the
reformulated gasoline program. Section 211(k)(3) specifies that the
minimum requirement for reductions of volatile organic compounds (VOC)
and toxics for 1995 through 1999, or Phase I of the reformulated
gasoline program, must require the more stringent of either a formula
fuel or an emission reductions performance standard, measured on a mass
basis, equal to 15 percent of baseline emissions. Baseline emissions
are the emissions of 1990 model year vehicles operated on a specified
baseline gasoline. CAA compositional specifications for reformulated
gasoline include a 2.0 weight percent oxygen minimum and a 1.0 volume
percent benzene maximum.
For the year 2000 and beyond, the Act specifies that the VOC and
toxics performance standards must be no less than that of the formula
fuel or a 25 percent reduction from baseline emissions, whichever is
more stringent. EPA can adjust this standard upward or downward taking
into account such factors as feasibility and cost, but in no case can
it be less than 20 percent. These are known as the Phase II
reformulated gasoline performance standards. Taken together, sections
211(k)(1) and 211(k)(3) call for the Agency to set standards that
achieve the most stringent level of control, taking into account the
specified factors, but no less stringent than those described by
section 211(k)(3).
The reader may refer to the April 16, 1992 SNPRM (57 FR 13416) and
the February 26, 1993 NPRM (58 FR 11722) described in more detail
below), the February 1993 Draft Regulatory Impact Analysis (DRIA), the
Final Regulatory Impact Analysis (RIA), and Public Dockets A-91-02 and
A-92-12 for a thorough description of the goals and regulatory
development of the reformulated and anti-dumping programs and
discussions of a number of associated technical issues.
A. Regulatory Negotiation (Reg Neg)
Shortly after passage of the Clean Air Act Amendments of 1990, EPA
entered into a regulatory negotiation with interested parties to
develop specific proposals for implementing both the reformulated
gasoline and related anti-dumping programs. These parties included
representatives of the oil and automobile industries, vehicle owners,
state air pollution control officials, oxygenate suppliers, gasoline
retailers, environmental organizations, and citizens' groups. (See the
1991 NPRM for the members of the negotiating committee and a discussion
of the process for selecting them.)
In August 1991 the committee reached consensus on a program outline
and signed an ``Agreement in Principle'' describing that consensus. EPA
agreed to propose a two-step approach to reformulated gasoline. The
first step would take effect in 1995 and utilize a ``simple model'' to
certify that a gasoline meets applicable emission reduction standards.
The simple model allows certification based on a fuel's oxygen,
benzene, heavy metal and aromatics content and Reid Vapor Pressure
(RVP).
Under the second step, according to the regulatory negotiation
agreement, EPA would propose a ``complex model'' to supplant the simple
model for certifying compliance with these standards. Certification
under the complex model would take effect 4 years after it is
promulgated. EPA also agreed to propose the more stringent Phase II
emission performance standards.
B. July 9, 1991 NPRM (56 FR 31176)
The first NPRM for the reformulated gasoline program was published
prior to the conclusion on the regulatory negotiations. Normally, in a
negotiated rulemaking, such a reg-neg committee meets to develop a
proposed rule which will be acceptable to all parties. If consensus is
reached on a proposed rule, it is published as an NPRM. The committee
members and the entities they represent agree to support the proposal
and not to seek judicial review of the final rule if it has the same
substance and effect as the consensus proposal. In this case, EPA
published an NPRM while the advisory committee was still conducting
negotiations. The Agency believed that although consensus of the
members on an acceptable rule was possible, an NPRM was required at
that time in order to meet the statutory deadline.
The 1991 NPRM described the provisions of both a program to require
the sale of gasoline which reduces emissions of toxics and ozone-
forming volatile organic compounds (VOCs) in certain nonattainment
areas and a program to prohibit the gasoline sold in the rest of the
country from becoming more polluting. The 1991 notice described the
outline of the reformulated gasoline program as required by statutory
provisions and options that the regulatory negotiation committee
members were considering. Topics included in the 1991 proposal
consisted of the derivation of the emission standards, fuel
certification by modeling, opt-in provisions, credits, anti-dumping
requirements, and enforcement provisions for all aspects of the
reformulated gasoline program.
C. April 16, 1992 SNPRM (57 FR 13416)
As noted above, the Agency's SNPRM (57 FR 13416) reflected the
agreement reached in the regulatory negotiation that had been conducted
to develop reformulated gasoline regulations under section 211(k). The
Supplemental Notice of Proposed Rulemaking (SNPRM) described the
standards and enforcement scheme for both reformulated and conventional
gasoline. It also included specific proposals for the simple emission
model to be used in gasoline certification and enforcement.
D. February 26, 1993 NPRM (58 FR 11722)
In their comments on the SNPRM, the ethanol industry expressed
concern that the reformulated gasoline rulemaking, as proposed in the
SNPRM, effectively excluded ethanol from the reformulated gasoline
market. In an attempt to address their concern, the Agency proposed an
ethanol incentive program, at the direction of former President Bush,
intended to promote the use of ethanol (and other renewable oxygenates)
in reformulated gasoline. The objective of the proposed renewable
oxygenate program was to enhance the market share for renewable
oxygenates while, theoretically, maintaining the overall environmental
benefits of the reformulated gasoline simple model. This would be
accomplished by offsetting any increase in volatility that may result
from the inclusion of ethanol with volatility reductions that occur in
the rest of the RFG pool. This volatility balancing, however would not
take into account any increase in volatility in-use due to mixing of
ethanol and non-ethanol gasoline blends (commingling). The renewable
oxygenate program would not be required in class B areas (the South)
unless a state requested inclusion in the program. Thus, the NPRM (58
FR 11722) for reformulated gasoline proposed revisions to the simple
model, as well as to the associated anti-dumping, and enforcement
provisions. Also included in the NPRM were the proposed complex model
for certification of reformulated gasoline and the proposed Phase II
performance standards. The complex model is now scheduled to take
effect January 1, 1998. The complex model will provide a method of
certification based on the fuel characteristics such as oxygen,
benzene, aromatics, RVP, sulfur, olefins and the percent of fuel
evaporated at 200 and 300 degrees Fahrenheit (E200 and E300,
respectively). The NPRM also proposed Phase II standards for
reformulated gasoline which are to take effect in the year 2000, as
prescribed by section 211(k)(3) of the Clean Air Act (CAA). The
proposed VOC performance standard was 20-32 percent for class B and 26-
35 percent for class C. EPA proposed to set the toxic standard at 20 or
25 percent reduction since additional toxics control was not found to
be cost effective and, in most cases, these greater toxics reductions
were expected to occur through fuel reformulation for VOC control. The
NPRM also included proposed NOx performance standards of 0-16
percent in classes B and C. The proposed NOx standards greater
than zero were not required by the CAAA, but were proposed under the
authority of section 211(c)(1) in conjunction with the Phase II
reformulated gasoline standards of the Act since additional NOx
control was deemed beneficial and cost effective in reducing ambient
ozone levels.
E. Discussion of Major Comments and Issues
EPA received a number of comments on the first NPRM (56 FR 31176),
the SNPRM (57 FR 13416), and the latest NPRM (58 FR 11722) for
reformulated and conventional gasoline. Comments covered a wide range
of topics including regulatory procedure, certification standards,
modeling emissions by the simple and complex models, the role of
ethanol and other oxygenates in reformulated gasoline, vehicle testing,
the anti-dumping program, Phase II standards, cost-effectiveness, and a
number of enforcement-related issues. EPA has conducted an analysis of
the comments received and duly considered the significant issues.
Summaries of these comments and EPA's responses to them are contained
in the Final Regulatory Impact Analysis and the Summary and Analysis of
Comments which has been placed in the docket for this rulemaking
(Public Docket No. A-92-12). Since the publication of the NPRM, the
Agency has continued to develop the complex model. The first revisions
of the complex emissions model since 1993 NPRM publication for
reformulated gasoline have been provided to the public at a June 2,
1993 public workshop. EPA developed several complex model options in
July which was provided to the public. In October of 1993, a draft
version of the final complex model was released for public inspection
as well. All the iterations of the complex model since the publication
of the 1993 NPRM have been available to the public via a public
electronic bulletin board and in submittals to the EPA Air Docket,
Docket No. A-92-12.
All the various components of this rulemaking are being finalized
in today's notice. The additional time has allowed adequate public
review of the complex model and its implications for the reformulated
gasoline Phase II standards.
The remainder of this preamble is organized into the following
sections:
II. Treatment of Ethanol
III. Simple Model for Reformulated Gasoline Compliance
IV. Complex Model
V. Augmenting the Models Through Testing
VI. Phase II (Post-1999) Reformulated Gasoline Performance
Standards and NOx Standards for Reformulated Gasoline
VII. Enforcement
VIII. Anti-Dumping Requirements for Conventional Gasoline
IX. Anti-Dumping Compliance and Enforcement Requirements for
Conventional Gasoline
X. Provisions for Opt-In by Other Ozone Non-Attainment Areas
XI. Federal Preemption
XII. Environmental and Economic Impacts
XIII. Public Participation
XIV. Compliance With the Regulatory Flexibility Act
XV. Statutory Authority
XVI. Administrative Designation and Regulatory Analysis
XVII. Compliance With the Paperwork Reduction Act
XVIII. Notice Regarding Registration of Reformulated Gasolines
II. Treatment of Ethanol
A. Background
The April 16, 1992 proposal of the Simple Model and Phase I
standards was designed to be fuel and oxygenate neutral. Ethanol,
however, when added to gasoline in the amount needed to satisfy the
oxygen content requirement of the Act raises the Reid vapor pressure
(RVP) of the resulting blend by about 1 psi, making it more difficult
for ethanol blends to meet the mass VOC performance standards than
blends using other oxygenates. For ethanol to be blended with the RFG,
a blendstock gasoline with an RVP low enough to offset the increase
resulting from adding ethanol would have to be obtained.
Ethanol industry representatives commented that obtaining such
blendstocks would be both difficult and expensive, because ``sub-RVP''
blendstocks would be more costly to refine and because blendstock
production would be controlled by petroleum refiners. Methyl tertiary
butyl ether (MTBE), an oxygenate which does not boost a fuel's RVP,
which is derived from methanol gas and the petroleum product
isobutylene and whose blends can readily be put through petroleum
pipelines, was thought to be the oxygenate of choice for most refiners.
Ethanol's representatives theorized that the oil industry would have a
desire to use MTBE over ethanol and, thus, little incentive to make the
sub-RVP blendstock necessary for ethanol blending. The ethanol industry
contended that a reformulated gasoline program which they argued would
effectively preclude ethanol was contrary to Congress' intent that
ethanol have a role in the program. They argued that the oxygen content
requirement of section 211(k)(2) was motivated in large part by a
desire to expand markets for ethanol. They noted the strong support
afforded the RFG legislative initiative by members of Congress from
agricultural states. They also cited statements in the legislative
history indicating some members' expectation that the RFG program would
provide an increasing market for ethanol.
Ethanol representatives contended that the benefits of ethanol use
justify its inclusion in the RFG program. Specifically, they explained
that ethanol is currently made in the United States from domestically-
grown grains, primarily corn, and thus represents an important domestic
and renewable source of energy. They further explained that to the
extent ethanol is used in place of imported petroleum products, it
promotes the nation's energy independence and improves its balance of
trade, and that ethanol use also strengthens the market for corn,
consequently reducing the need for price supports. Moreover, as a
biomass-based product, ethanol is potentially a renewable fuel to the
extent the energy derived exceeds any fossil fuel energy consumed in
producing the ethanol.
In view of ethanol's importance to the nation's energy security and
agricultural economy, ethanol representatives urged that the proposal
be revised to allow ethanol to effectively participate in the RFG
market. They suggested several possible revisions. For example, they
argued that the 1 psi waiver granted to certain ethanol blends by
section 211(h) of the CAA be applied to ethanol-blended RFG under
section 211(k). They reasoned that since Congress recognized in the
provision requiring nationwide reductions in fuel RVP that ethanol
required such a waiver, ethanol should receive a similar waiver if the
VOC performance standard for RFG sold in the smoggiest cities were
defined in terms of a required reduction in RVP.
If the section 211(h) waiver were not available to RFG ethanol
blends, the ethanol industry suggested that the VOC reduction
requirement take into account that specific VOCs from various
reformulated gasolines differ in their ozone formation potential. While
ethanol raises a fuel's volatility and thus its VOC emissions, they
argued that the resulting VOCs are less ozone-forming than those that
would otherwise occur. They urged that the 15 percent reduction
requirement should thus be interpreted to require a 15 percent
reduction in ozone-forming potential, not simply mass of ozone-forming
VOCs. Ethanol supporters suggested additional ways of encouraging or
even requiring ethanol use in RFG. The Governors Ethanol Coalition, for
instance, suggested that EPA require the RFG market to satisfy its
oxygenate requirements through a minimum percentage of domestically
produced renewable fuel.
Based on ethanol's importance to the nation's energy and
agricultural policy, President Bush on October 1, 1992 announced a plan
to allow ethanol to effectively compete in the RFG program, with the
expectation that, with barriers removed, ethanol use would grow. In
lieu of an RVP waiver, or inclusion of ozone reactivity this plan was
based upon provisions of section 211(k)(1) allowing the Administrator
to take into consideration cost, energy requirements, and other
specified factors in setting RFG performance standards. The most
significant part of this plan called for EPA to ``establish rules for
reformulated gasoline in all northern cities that will have the effect
of granting a one-pound waiver for the first 30 percent market share of
ethanol blends, while achieving environmental benefits comparable to
those provided for in EPA's proposed rule and regulatory negotiation.''
The environmental benefits of the proposed RFG program would be
maintained by offsetting any increase in volatility of RFG containing
ethanol with reductions in the volatility of the rest of the
reformulated gasoline pool. In response to the announcement by former
President Bush, EPA proposed on February 26, 1993 provisions to provide
an RVP (and VOC) incentive for the use in reformulated gasoline of
renewable oxygenates such as ethanol.
B. Concerns With the Proposal
At the time of the February 26, 1993 proposal, EPA had a number of
concerns with respect to its legality, energy benefits, and
environmental neutrality. Nevertheless, we proposed the provisions for
public comment in the hope that these concerns could be overcome based
on new data and information developed in-house or received through
public comment. Since the time of the proposal these concerns have been
enhanced. Additional data and information has been developed which
indicates that energy benefits would be unlikely to occur as a result
of the proposal. While the production of much of the ethanol in the
country produces on the margin more energy and uses less petroleum than
went into its production, a recent study by the Department of Energy
(refer to DOE's comments on the proposal) indicates that the margin
disappears when ethanol is mixed with gasoline. The energy loss and
additional petroleum consumption necessary to reduce the volatility of
the blend to offset the volatility increase caused by the ethanol
causes the energy balance and petroleum balance to go negative. Since
the potential energy benefits were the basis in the proposal for
providing the incentives for renewable oxygenates, the justification
for the proposal no longer exists.
Additional data and information has also been developed which
indicates that VOC emissions would increase significantly under the
proposal. As discussed in section I of the RIA, the commingling effect
of mixing ethanol blends with non-ethanol blends in consumer's fuel
tanks, the effect of ethanol on the distillation curve of the blend,
and unrestricted early use of the complex model combined result in
roughly a 6-7.5% increase in gasoline vehicle VOC emissions even though
there is no increase in the average RVP of in-use gasoline. As a
result, the proposal would have sacrificed 40 to 50 percent of the VOC
control that is required under section 211(k) for reformulated gasoline
in exchange for incentives for what is likely to have been only a
marginal increase in the market share of ethanol in reformulated
gasoline and no energy benefits or cost savings.
As discussed in section I of the RIA, ethanol is not excluded from
competing in the reformulated gasoline market under the provisions of
the April 16, 1992 SNPRM. As a result of the economic advantage of
ethanol over other oxygenates, ethanol should maintain a significant
market share under the reformulated gasoline program even without the
renewable oxygenate incentives proposed in the February 16, 1993
proposal. As a result, the actual ethanol market share increase as a
result of the renewable oxygenate provisions would be expected to be
far less than the maximum of 30% for which incentives were provided.
Given the relatively small increase in ethanol demand as a result of
the renewable oxygenate provisions in exchange for such a large loss in
the environmental control of the reformulated gasoline program, there
does not appear to be any justification for promulgating these
provisions.
Furthermore, comments were received from virtually all parties,
including ethanol industry representatives, that the proposal was
unworkable and would significantly increase the cost of the
reformulated gasoline program. While EPA maintains that the program
would have provided an economic incentive for the use of renewable
oxygenates in reformulated gasoline up to a 30% market share, EPA
acknowledges that the proposal would have intruded into the efficient
operation of the marketplace, impacting the cost of the reformulated
gasoline program. As a result, after taking into account the cost, non-
air quality and environmental impacts, and energy impacts, EPA has
found itself with no choice but to back away from the renewable
oxygenate provisions of the February 26, 1993 proposal.
C. Provisions for the Final Rule
In lieu of the renewable oxygenate proposal, EPA investigated a
number of options aimed at making the program more workable by reducing
the fuel tracking, recordkeeping, and enforcement burden associated
with the proposal. While such options tended to make the program more
workable from the standpoint of the refining and fuel distribution
processes, they also tended to either reduce the assurance that the
environmental benefits of the program would be achieved in all areas
covered by the RFG program, or to place additional restrictions on the
flexibility contained in the proposal for blending ethanol into
gasoline. Given this and the other concerns with the proposal (cost,
lack of energy benefits, significant environmental loss, etc.), EPA did
not believe these options to be appropriate or justifiable either under
the provisions of section 211(k) of the Act. The reader is referred to
the Final Regulatory Impact Analysis for a detailed discussion of the
renewable oxygenate program.
A number of commenters suggested alternative provisions (1.0 psi
RVP waiver for ethanol blends, inclusion of ozone reactivity in the
standard setting process, mandates for refiners to provide clear
gasoline blendstock for downstream blending with ethanol, etc.) to the
proposed renewable oxygenate program to allow ethanol to play a larger
role in the reformulated gasoline program. It was argued that without
such provisions ethanol would be excluded from the market entirely in
direct conflict with the intent of Congress in the CAA.
EPA, however, does not agree that ethanol is excluded from
competing in the reformulated gasoline marketplace under the provisions
of the April 16, 1992 proposal. In fact, as under the recently
implemented wintertime oxygenated fuels program, ethanol is expected to
significantly increase its market share under the reformulated gasoline
program, especially in Midwestern areas where ethanol enjoys State tax
incentives and relatively low distribution costs. In addition, not only
is ethanol expected to compete as an alcohol, but it also may compete
with methanol as an ether feedstock in the future. As a result, EPA
believes that the treatment of ethanol blends under the April 16, 1992
proposal is entirely consistent with the intent of Congress as
expressed in section 211(k) of the CAA.
The alternative provisions (1.0 psi RVP waiver for ethanol blends,
inclusion of ozone reactivity in the standard setting process, mandates
for refiners to provide clear gasoline blendstock for downstream
blending with ethanol, etc.) suggested by various commenters to further
enhance the competitiveness of ethanol in the reformulated gasoline
program are not appropriate. These provisions are both outside of EPA's
legal authority under the CAA, and indefensible from an environmental
and scientific standpoint. The 1.0 psi waiver for example, could easily
forfeit all VOC emission reductions otherwise achieved by the
reformulated gasoline program. A move away from the mass based
standards of the Act to reactivity based standards is not only
unsupportable on the basis of the available scientific information, but
even if EPA were able to do so, it would be unlikely to provide any
significant advantage for ethanol blends. As discussed in section I of
the RIA, the recent urban airshed modeling studies claiming that
ethanol blends with a 1.0 psi waiver do not increase ozone relative to
an MTBE blended reformulated gasoline are frought with invalid
assumptions and inconsistencies and are not applicable to the
reformulated gasoline situation. As a result, they provide no credible
scientific support for special provisions for ethanol in the context of
the reformulated gasoline program.
Given the lack of justification for the renewable oxygenate
provisions of the February 26, 1993 proposal, the options considered
for simplifying that proposal, and other alternative provisions
recommended by commenters, EPA is, thus, basing the oxygenate-related
provisions of the final rule on the provisions as proposed in the April
16, 1992 proposal. Despite this decision, EPA still believes ethanol
will be able to compete favorably in the reformulated gasoline market
either as a direct additive or as an ether feedstock as discussed
above. As such, EPA believes that the nationwide production of ethanol
will increase as a result of this rulemaking with corresponding
benefits to our Nation's agricultural sector. However, the increase may
not be as large as it otherwise would have been had an incentive
program been promulgated for ethanol. The reader is referred to section
I. of the RIA for additional description of the comments and
information which led up to this decision.
III. Simple Model for Reformulated Gasoline Compliance
In accordance with section 211(k) of the Clean Air Act, EPA
requires that in order for a gasoline to be certified as reformulated,
it must contain at least 2.0 weight percent oxygen, no more than 1.0
volume percent benzene, and no heavy metals (unless a waiver is
granted); result in no increase in NOX emissions; and achieve
required toxics and VOC emission reductions. The VOC, NOX, and
toxics emission requirements effective between January 1, 1995 and
December 31, 1997 and EPA's derivation of them are set forth below.
Two methods by which refiners can certify their fuel as meeting the
VOC, NOX, and toxics requirements of reformulated gasoline are
contained in this rulemaking. The first, by use of a ``Simple Model,''
is described in this section. A second method, the use of the ``Complex
Model'' is described in Section IV. Provisions for augmenting the
Complex Model through vehicle testing are described in Section V. For
reasons set forth in the April 16, 1992 SNPRM (57 FR 13417-13418) and
discussed Section V, vehicle testing is not an option as a separate,
stand-alone method of certification. First, models can better reflect
in-use emission effects since they can be based on the results of
multiple test programs. Second, individual test programs may be biased,
either intentionally or unintentionally. Third, fuel compositions tend
to vary due in part to factors beyond the control of fuel suppliers,
potentially requiring testing of each batch if a model is not used.
Finally, models make more efficient use of scarce and expensive
emissions effects data than is otherwise possible. For these reasons,
EPA believes that the modeling options promulgated by EPA are necessary
for the reformulated gasoline program to achieve its environmental
objectives and to minimize the costs of the program. Comments were
received suggesting that EPA allow certification based on testing as an
optional means of certification. However, for the same reasons
discussed above, EPA does not believe such an option would be
appropriate. EPA would have much less certainty that the results of the
test program were valid.
At the time of the simple model proposal, while a number of fuel
parameters were thought to impact emissions, data were sufficient for
only a few of these parameters (Reid vapor pressure, fuel oxygen,
benzene, and aromatics) to quantify their effect with reasonable
accuracy for use in an emissions model. For those additional parameters
which were thought to impact emissions in a directionally clear, but as
of yet unquantifiable manner (sulfur, T90, and olefins), EPA proposed
that they be capped at the refiner's 1990 average level to prevent
emission effects from changes in their levels from undercutting the
emission reductions achieved by the parameters contained in the simple
model. The effect of aromatics on VOC and NOX emissions was also
unclear, but instead of being capped, it was believed that the level of
aromatics would be controlled by the role aromatics plays in the
formation of air toxics emissions.
Data is now available to accurately quantify not only the effects
of RVP, oxygen, benzene, and aromatics on emissions, but also sulfur,
T90 (or E300), olefins, and T50 (or E200). The effects of these fuel
parameters are incorporated into the Complex Model described in Section
IV.
The Complex Model is the most accurate and complete model currently
available for use in the reformulated gasoline program. Absent any
other considerations, EPA would require use of the Complex Model for
purposes of certification. However, based on leadtime considerations,
EPA is allowing use of either the Simple or Complex Model during the
first three years of the reformulated gasoline program as proposed.
These lead time considerations were described in the April 1992
proposal (57 FR 13417-8). EPA is providing four years leadtime before
use of the Complex Model is mandatory to allow the regulated industry
adequate time to plan and design necessary refinery modifications,
obtain necessary permits and capital, complete construction, and
complete start-up and equipment shakedown. Furthermore, EPA has every
confidence that on average the refiners certifying their fuel using the
Simple Model will achieve the emission reductions that Congress
intended for the reformulated gasoline program.
Various comments were received criticizing the use of the Simple
Model for fuel certification, stating that it had limited flexibility,
discouraged innovation, penalized refiners producing cleaner than
average gasoline in 1990, and should be scrapped. Many of these
comments would appear to be resolved by the option available for early
use of the Complex Model. Therefore, in keeping with the need to
provide adequate lead time and the fact that compliance with the Simple
Model will produce the mandatory VOC and toxic emission reductions,
refiners will be permitted to use the simple model for certification
until December 31, 1997. Until this date, fuel suppliers will have the
option of using the complex model instead of the simple model to take
advantage of the effects of parameters contained in the complex model
but not contained in the simple model (as described in the following
paragraphs). The reader is referred to the April 16, 1992 SNPRM for
more discussion of these lead time provisions.
A. Simple VOC Emissions Model
The simple model for VOC emissions is comprised of fuel
specifications for RVP and oxygen. Fuels sold at retail outlets must
have an RVP during the high ozone season (June 1 through September 15)
of no more than 7.2 psi in VOC control region 1 (the southern areas
typically covered by ASTM class B during the summer) and 8.1 psi in VOC
control region 2 (the northern areas typically covered by ASTM class C
during the summer).1 The differences in climate between these two
types of areas requires a corresponding difference in gasoline
volatility to achieve the same emissions effect. The period of June 1
through September 15 was chosen for the high ozone season because most
of the ozone violations occur during this period. (See 56 FR 24242 for
a discussion of the determination of this period.)
---------------------------------------------------------------------------
\1\Lower RVP limits apply for fuels that comply under averaging.
RVP controls also apply from May 1 to May 31 for facilities upstream
of retail outlets. These issues are discussed elsewhere in this
proposal.
---------------------------------------------------------------------------
Section 211(k)(3) of the Act requires that at a minimum
reformulated gasoline comply with the more stringent of either a 15%
reduction in VOC emissions or a formula fuel described in that section,
whichever is greater. EPA has determined that the formula fuel would
achieve less than a 15% reduction in VOC. As such, the minimum VOC
emission reduction required by the Act is 15%. As discussed in section
IV, EPA believes that the VOC emission reduction in VOC control region
2 from a fuel with an RVP of 8.1 psi and 2.0 weight percent oxygen will
be sufficient to achieve the minimum 15% VOC emission reduction
relative to the Clean Air Act baseline gasoline (which has an RVP of
8.7 psi). In VOC control region 1, an 8.1 psi RVP fuel with 2.0 percent
oxygen (which would meet the minimum 15% reduction requirement relative
to the CAA baseline fuel) would actually have greater emissions than a
fuel meeting EPA's Phase II RVP control standards for VOC control
region 1 (maximum RVP of 7.8 psi). EPA believes that when Congress
designated cities for inclusion in the reformulated gasoline program
that it intended the program to provide emissions reductions in
addition to those provided by the Phase II RVP requirements. If EPA
merely required reformulated gasoline in VOC control region 1 to meet
the RVP requirement for VOC control region 2, then no reduction in VOC
emissions would accrue under the first phase of the reformulated
gasoline program beyond those mandated by Phase II RVP standards. EPA
projects that relative to Phase II RVP control levels, a fuel with 7.2
psi RVP and 2.0 weight percent oxygen would provide VOC emission
reductions in VOC control region 1 similar to those obtained in VOC
control region 2.
While requiring reformulated gasoline sold in VOC control region 1
to have an RVP of no more than 7.2 psi goes beyond the minimum
requirement stated in section 211(k)(3), section 211(k)(1) authorizes
EPA to require emission reductions in VOC control region 1 of this
magnitude because they are achievable considering costs, other air
quality and non-air quality impacts, and the energy implications of
such a requirement.
Similarly, EPA believes that additional VOC reductions are
obtainable if refiners are allowed to meet the RVP and oxygen standards
through averaging. If refiners wish to take advantage of averaging, EPA
thus will require their average RVP for both VOC control regions 1 and
2 to be reduced by 0.1 psi to 7.1 and 8.0 psi, respectively, and the
average oxygen concentration to be increased to 2.1 weight percent
oxygen. For additional discussion of the rationale for the more
stringent standard in VOC control region 1 and the increase in
stringency of the averaging standards, the reader is referred to the
April 16, 1992 SNPRM.
B. Simple NOx Emissions Model
The Clean Air Act requires that there be no NOX emissions
increase from reformulated fuels. Based on data available during the
regulatory negotiations and at the time of the April 16, 1992 proposal,
it appeared that fuel oxygen content and the type of oxygenate used may
have an impact on NOX emissions while no other simple model
parameter appeared to have such an impact. Due to the statutory
requirement for oxygenate use, and the lack of any other parameters in
the simple model by which refiners could offset any NOX increase,
EPA needed to place restrictions on the amount of oxygen that could be
added to the fuel in order to prevent NOX emission increases. EPA
proposed on the basis of the data then available that MTBE blends
containing up to 2.7 weight percent (wt%) oxygen and other blends
containing up to 2.1 wt% oxygen would be presumed to result in no
NOX increase. Greater oxygenate concentrations could not be
permitted due to the risk of NOX emission increases.
When additional data became available, however, there did not
appear to be any significant difference between the NOX emission
effects of oxygen from different oxygenates. Furthermore, it appeared
that reducing the concentration of a number of additional fuel
parameters (aromatics, olefins, sulfur, etc) could reduce NOX
emissions. Since these fuel parameters all tend to be reduced to
varying degrees when oxygenates are added to gasoline, EPA proposed in
its February 26, 1993 proposal that all oxygenates be assumed to result
in no NOX emission increase under the simple model up to 2.7 wt%
oxygen.
Under the final Complex Model discussed in Section IV, oxygen has
been found to result in no NOX increase, in fact, it results in a
very slight decrease. However, the other changes that occur to the fuel
when oxygenates are added both increase and decrease NOX emissions
(increases in E200 increase NOX emissions while reductions in
sulfur, olefins, aromatics, and increases in E300 reduce NOX
emissions). Typically the effect of these other fuel changes will be to
further reduce NOX emissions. However, there is no control placed
on E200 levels under the simple model, and the levels of sulfur,
olefins, an E300 are only constrained to the refiner's 1990 baseline
levels (aromatics is controlled indirectly to some degree by the toxics
requirement). As a result, there is no assurance under the simple model
that oxygenate addition will not increase NOX emissions. The more
oxygenate added, the greater the increase in E200, and the greater the
possibility for a NOX increase. For this reason EPA believes it is
still appropriate to cap the maximum oxygen content under the Simple
Model at 2.7 wt%. Any higher oxygen concentrations will require use of
the complex model.
However, for a number of reasons, EPA believes it is appropriate
for any oxygenate up to 3.5 weight percent oxygen to be presumed to
result in no NOX emission increase under the simple model during
those months without ozone violations (e.g., winter months) unless a
state requests that oxygenate levels be limited to the 2.7 wt% oxygen
level applicable during those months with ozone violations. First,
although there are a number of concerns associated with NOX
emissions, the main concern of focus in this rulemaking is ozone which
is for the most part a summertime problem. Second, while there is no
assurance that individual batches of gasoline containing more than 2.7
wt% oxygen will not increase NOX emissions, the increase, if any,
would be small (i.e., likely less than 1 percent). Third, on average
across all fuel produced by all refiners in an area, a NOX
reduction may still occur. Fourth, there are benefits to the use of
oxygenates during the winter months (lower CO and air toxics emissions)
that may be more important to individual states than the certainty that
no one batch of fuel increases NOX emissions relative to the 1990
baseline.
A state may make a request for the 2.7 wt% oxygen limit to apply
during the non-ozone season when it believes that the use of higher
oxygenate levels would interfere with attainment or maintenance of
another ambient air quality standard (other than ozone) or another air
quality problem. This proposal parallels the Regulatory Negotiation
Agreement of August 16, 1991 and EPA's letter to the Renewable Fuels
Association dated August 14, 1991.
C. Simple Toxics Emissions Model
Under section 211(k)(3), EPA must at a minimum require the more
stringent of either a specified formula fuel or a 15 percent reduction
in toxics emissions from that of baseline gasoline. All five of the
toxic air pollutants that section 211(k)(10) of the Act specifies for
control through reformulated gasoline (benzene, 1,3-butadiene,
polycyclic organic matter (POM), formaldehyde, and acetaldehyde) also
fall under the category of VOCs. Exhaust emissions include unburned
benzene and benzene formed from other aromatics during the combustion
process. Benzene, an aromatic compound, is a natural component of
gasoline and, as such, is present in evaporative, running loss and
refueling emissions (nonexhaust emissions). However, nonexhaust VOC and
benzene emissions data are only available in sufficient quantities
under high ozone test conditions. Therefore, nonexhaust benzene
emissions are not considered outside of the high ozone season. The four
other toxic air pollutants subject to control by reformulated gasoline
are not present in gasoline and hence are solely products of
combustion.
The equations that represent the simple model for air toxics
emissions are shown in section 80.42 of the regulations. The derivation
and referenced work is given in the regulatory impact analysis.
Only minor changes were made to the proposed simple toxics model.
One change excluded ethane from the exhaust VOC baseline emissions as
discussed below in Section III.D.3. The weight fractions of the various
toxics as a function of VOC have also been adjusted accordingly,
resulting in no net change in predicted toxics performance for a
particular fuel. At the request of commenters, EPA has also included
the oxygenates tertiary amyl methal ether (TAME) and ethyl tertiary
amyl ether (ETAE) as well as provisions for other oxygenates and mixed
oxygenates. Due to their similar chemical makeup, methyl ethers (such
as TAME) and ethyl ethers (such as ETAE) are to be modeled using the
same equations as for MTBE and as for ETBE, respectively. Higher
alcohols will be modeled using the same equations as for ethanol.
Higher ethers will be modeled as ETBE for all air toxics, since ETBE
was the highest ether for which toxics data were available.
D. Baseline Determination
Where the performance standard is more stringent than the formula,
the Act requires EPA to promulgate standards for the performance of
reformulated gasoline that are relative to emission levels from
baseline vehicles using baseline fuel. In order to determine whether
fuels meet the performance requirements of reformulated gasoline under
the simple model, EPA must therefore establish the baseline to which
the emission performance of reformulated fuels are to be compared. The
following discussion describes how EPA derived the emission baselines.
1. Control Periods
Before the emission baselines can be determined, the time frame
over which fuel performance will be evaluated must be identified.
Section 211(k) of the Act requires control of VOC emissions during the
``high ozone season.'' For the purposes of this rulemaking, the high
ozone season is defined to be June 1 through September 15. This period
covers the vast majority of days during which the national ambient air
quality standard for ozone is exceeded nationwide and is consistent
with the period covered by EPA's gasoline volatility control
requirements. All gasoline at service stations must thus comply with
the reformulated gasoline requirements during this period. Also in
keeping with the gasoline volatility control rulemaking the ``VOC
control Period'' for compliance with the reformulated gasoline
provisions upstream from the service station (necessary to ensure
complying fuel is available at the service stations during the high
ozone season) is May 1 through September 15.
2. Baseline Gasoline
The fuels to be used in determining baseline emissions are
unchanged from the February 26, 1993 proposal and are shown below.
Table III-1.--Baseline Fuel Compositions
------------------------------------------------------------------------
Summer Winter
------------------------------------------------------------------------
Sulfur, ppm....................................... 339 338
Benzene, volume percent........................... 1.53 1.64
RVP, psi.......................................... 8.7 11.5
Octane, R+M/2..................................... 87.3 88.2
T10, degrees F.................................... 128 112
T50, degrees F.................................... 218 200
T90, degrees F.................................... 330 333
Aromatics, volume percent......................... 32.0 26.4
Olefins, volume percent........................... 9.2 11.9
Saturates, volume percent......................... 58.8 61.7
------------------------------------------------------------------------
3. Definition of Ozone-Forming VOC
The Act requires reductions in emissions of ozone-forming VOCs.
This interpretation is consistent with the focus of Section 211(k) on
the areas with the most extreme ozone pollution problem. EPA proposed
in April 16, 1992 that methane would be excluded from the definition of
VOC on the basis of its low reactivity in keeping with past EPA
actions, but included all other VOCs including ethane. EPA further
proposed, however, that should the Agency modify the definition of VOC,
we might do so for the reformulated gasoline rulemaking as well. As
discussed in the February 26, 1993 proposal, EPA has also modified the
definition of VOC to exclude ethane in a separate Agency rulemaking (57
FR 3941). As a result, the performance of fuels meeting the VOC
emission requirements under the simple model are expressed on a non-
methane, non-ethane basis. This change resulted in slight changes to
the simple model equations previously proposed, but the overall results
of the simple model are essentially unaffected.
4. Simple Model Baseline
The following table shows the baseline emissions under the simple
model which result from the assumptions discussed above. Since the
MOBILE model does not estimate toxics emissions, however, separate data
and information was necessary to determine their baseline emissions.
The toxics baseline was developed in essentially the same manner as
that proposed in the April 16, 1992 proposal. An explanation of this
derivation can be found in Section II of the RIA.
Table III-2.--Simple Model Baseline Emissions
------------------------------------------------------------------------
Summer
-------------------------- Winter
Region 1 Region 2
------------------------------------------------------------------------
Exhaust VOCs (g/mi).............. 0.444 0.444 0.656
Non-Exhaust VOC (g/mi)........... .856 .766 0
Total VOCs (g/mi)................ 1.30 1.21 0.656
Exhaust Benzene (mg/mi).......... 30.1 30.1 40.9
Evaporative Benzene.............. 4.3 3.8 0.0
Running Loss Benzene............. 4.9 4.5 0.0
Refueling Benzene................ 0.4 0.4 0.0
1,3-Butadiene.................... 2.5 2.5 3.6
Formaldehyde..................... 5.6 5.6 5.6
Acetaldehyde..................... 4.0 4.0 4.0
POMs............................. 1.4 1.4 1.4
--------------------------------------
Total TAPs (mg/mi)........... 53.2 52.1 55.5
------------------------------------------------------------------------
E. Phase I Performance Standards Under the Simple Model
Section 211(k)(3) directs EPA to require, at minimum, that Phase I
reformulated gasoline comply with the more stringent of two alternative
VOC and toxics emission requirements--either a performance standard of
a 15 percent reduction from baseline levels on a mass basis, or
compositional requirements specified as a formula in Section
211(k)(3)(A). The formula effectively defines a set of maximum or
minimum fuel parameter specifications. In evaluating which requirement
is more stringent, EPA is to consider VOC and toxics separately.
The stringency of the formula is best evaluated by determining the
emissions performance of the fuels that would be certifiable if EPA
were to impose the requirements of Section 211(k)(3)(A). A gasoline
would meet these requirements if it (1) had no more than 1.0 volume
percent benzene, (2) had no more than 25 volume percent aromatics, (3)
had no less than 2.0 weight percent oxygen, and (4) met the
requirements for detergent additives and lead content. The formula does
not specify or limit any additional gasoline properties, and therefore
a wide variety of fuels with very different properties would qualify as
complying with the formula. For example, the formula specifies the
weight percent oxygen but does not specify the type of oxygenate. If
EPA were to impose the requirements of Section 211(k)(3)(A), then any
approved oxygenate could be used to meet the formula's oxygen
requirement, as long as it was blended to achieve the required weight
percent oxygen. The same would be true of sulfur levels, distillation
characteristics, olefin levels, RVP levels, and so on. As long as the
formula's requirements were met, the fuel would be certifiable if EPA
were to base its certification requirements on Section 211(k)(3)(A).
To evaluate the emissions performance of the various fuels that
would comply with the formula requirements, EPA used the Phase I
complex model. Given the Phase I baseline emission levels, EPA
considers the complex model to be the most appropriate means of
evaluating emissions performance since it incorporates the Agency's
most recent, complete, and accurate knowledge of the effects of fuel
properties on VOC and toxics emissions. Since many of the fuel
parameters that are not specified for the formula affect VOC and toxics
emissions, the various possible formula fuels exhibit a wide variety of
emission performance levels as these unspecified parameters vary.
According to the Complex Model, requirements based on many possible
formula fuels would be less stringent than requirements based on the 15
percent minimum reduction requirements of Section (211)(k)(3)(B). In
addition, the lack of specificity of the formula fuel would make
establishment of an equivalent emissions performance standard
impossible, since one or more possible formula fuels would fail to meet
any specific standard.
In past proposals, EPA has evaluated the formula fuel by assigning
levels for unspecified parameters at their level in baseline gasoline,
as defined in section 211(k)(9)(B) of the Act. However, such an
interpretation would not eliminate the problems described above, since
the oxygenate type would remain unspecified. Hence the requirements of
a formula could be met by a range of fuels, each based on different
oxygenates, even if unspecified parameters were to be set to baseline
levels, and this range of fuels would exhibit a range of emission
performance levels. While the Complex Model attributes identical
effects to oxygen in different chemical forms for most pollutants, it
incorporates emission effects that depend on the type of oxygenate used
for nonexhaust benzene, acetaldehyde, and formaldehyde emissions. EPA
therefore ran the complex model for several fuels, varying the type of
oxygenate and holding other parameters not specified by the formula at
statutory baseline levels.
The VOC emission reductions from baseline levels for all such
formula fuels were less than 15 percent. EPA therefore based the VOC
emission requirements for Phase I reformulated gasoline on the 15
percent reduction minimum performance standard, since this standard is
more stringent than the requirements of the formula.
For toxics performance, EPA separately evaluated the emissions
performance of fuels that met the formula requirements and contained
statutory baseline levels of unspecified fuel properties for VOC
control regions 1 and 2, since nonexhaust benzene emissions would
differ in these two regions. EPA also evaluated such fuels with
different oxygenate types. The results are shown in Table II-3. These
results include both summer and winter effects, weighted based on the
share of vehicle miles traveled in each season.
Table II-3.--Phase I Toxics Emissions Performance of Formula Fuels
------------------------------------------------------------------------
Percent reduction from
CAAB levels
Oxygenate type -------------------------
VOC control VOC control
region 1 region 2
------------------------------------------------------------------------
ETBE.......................................... 11.82 11.65
Ethanol....................................... 13.16 13.01
MTBE.......................................... 16.33 16.15
TAME.......................................... 16.81 16.67
------------------------------------------------------------------------
The results indicate that whether a formula fuel (with unspecified
fuel parameters at statutory baseline levels) meets the 15% minimum
performance requirement of section 211(k)(3)(B) depends on the type of
oxygenate used. If EPA were to impose the formula requirements of
section 211(k)(3)(A), the results presented in Table II-3 indicate that
not all gasolines which could be certified as reformulated would
achieve at least a 15 percent reduction in toxics mass emissions, even
if unspecified fuel properties were set at statutory baseline levels.
If EPA were to require a 15 percent emissions reduction in accordance
with section 211(k)(3)(B), however, all fuels would achieve this
minimum level of reductions. EPA therefore believes that the formula
requirements of section 211(k)(3)(A) are not as stringent as the
performance standard set forth in Section 211(k)(3)(B).
The minimum performance standard for Phase II is even more
stringent than the Phase I standards. EPA has therefore determined that
the performance standard is more stringent than the formula for both
VOCs and toxics, for both Phase I and Phase II. EPA must therefore set
its Phase I requirements for both VOCs and toxics to be no less
stringent than the 15 percent emission reduction performance standard
required by section 211(k)(3)(B). EPA has considered whether it should
require greater reductions in toxics mass emissions than that required
by the 15 percent minimum performance standard. However, the Agency has
concluded that more stringent toxics requirements are not cost-
effective, as is discussed more fully in Section VI. Hence EPA has set
the Phase I toxic emission performance standard at the minimum 15
percent reduction from baseline levels required by the Act. Compliance
with this standard must be demonstrated using the appropriate emission
models throughout Phase I.
Under the authority of section 211(k)(1), EPA believes that the
greater flexibility and reduced cost afforded to gasoline refiners and
importers by an averaging program allow EPA to require a greater
reduction in toxics emissions than is required under section 211(k)(3).
As discussed in Section VII, the Agency believes it appropriate, when
the air toxics standard is met on average, that it be 1.5 percentage
points more stringent than standards met on a per-gallon basis. EPA
estimates that the approximate 1.5 percentage point margin will be
sufficient to recoup any compliance margin refiners would have
otherwise had to maintain to ensure achievement of the toxics
requirements in the absence of an averaging program. In sum, the
tighter averaged standard should have the potential to increase the
environmental benefits of the reformulated gasoline program while not
increasing the cost of obtaining those benefits. As a result, the air
toxics performance standard when met on an annual average basis is set
at a 16.5% reduction from baseline levels.
F. Applicability (1995-7)
The Simple Model described in this section is effective beginning
January 1, 1995 with the beginning of the reformulated gasoline program
as a means by which fuel producers can certify that their fuel meets
the requirements for reformulated gasoline. The Complex Model described
in Section IV will not be required to be used for fuel certification
until January 1, 1998.
Until January 1, 1998, refiners who produce reformulated gasoline
will have a choice of certifying their gasoline by using either the
Simple Model or the Complex Model. EPA proposed three options for
establishing the performance standards under early, optional use of the
Complex Model. Under one option, if a refiner opts to utilize the
Complex Model before January 1, 1998 the reformulated gasoline can have
no worse VOC, NOX, or toxic emissions performance than would be
predicted by the Complex Model for a Simple-Model fuel (minimum 2.0
percent oxygen, maximum 1.0 percent benzene, and maximum RVP of 8.1 psi
in Class C areas and 7.2 psi in Class B areas) having that refiner's
average 1990 levels of sulfur, olefins, and T90 (E300). The second
option was a variation of the first, in that refiners producing
gasoline for use in only the southern reformulated gasoline areas (VOC
control region 1) could measure their fuel performance against the CAA
baseline gasoline as an alternative to their own 1990 refinery
baseline. The third option, proposed by EPA in February 1993, would
extend the second option to all reformulated gasoline areas.
The rationales for these options are discussed in detail in EPA's
proposals. Many of the comments were also received prior to the
proposals, and as such were addressed there. As a result, the reader is
referred back to the proposals for additional discussion. After
considering the comments, EPA has decided to promulgate the first
option. First, under this option each refiner will have to achieve the
same reductions, whether they use the simple model or the complex
model. The option to use either model increases refiner flexibility,
but will not change the emissions reductions required for a refiner
prior to mandatory use of the complex model in 1998. EPA believes that
the reductions required under the simple model are achievable
considering all relevant factors and will continue to be so under the
optional use of the complex model. In fact, the additional flexibility
of using the complex model would in some cases make them even more
reasonable.
Second, the other two options create an incentive for early use of
the complex model by those refiners who would then have a less
stringent performance standard than under the simple model. This would
produce on average an increase in overall emissions for reformulated
gasoline compared to average emissions if only the simple model was
allowed. Refiners with individual baselines for sulfur, T90 and olefins
that are lower than the CAA baseline would, under the second and third
options, get credit for emission benefits for these parameters, and
could use this to justify a less stringent RVP control than required
under the simple model. There would be no parallel disincentive to
early use of the complex model for refiners with higher baselines which
would result in an increase in their required reductions. This
imbalance in the expected early use of the complex model could easily
lead to an average 1-2 percentage point reduction in the average
emission performance of reformulated gasoline from 1995-7 as discussed
in section I of the RIA. Based on this negative environmental impact,
and the reasonableness of the complex model performance standard under
the first option, EPA has decided to promulgate the first option
described above for early use of the complex model.
G. Enforcement of the Early Use Option
Additional controls over reformulated gasoline certified using the
``early-use'' complex model are necessary for the operation of the
downstream enforcement mechanisms of VOC and NOX emissions
performance minimums, and covered area gasoline quality surveys. These
restrictions are necessary because under the restricted early-use
approach being promulgated, VOC, toxics, and NOX percentage
reductions are calculated from a baseline fuel using the refiner's 1990
baseline levels of sulfur, T-90, and olefins. As a result, the
reformulated gasolines produced by different refiners (or in some
cases, at different refineries) under this option will likely each meet
different percentage reduction standards for VOC, toxics, and NOX.
Therefore, the performance of a fungible mixture of complex model
gasolines produced by different refiners at different refineries could
not be predicted, nor could be evaluated.\2\
---------------------------------------------------------------------------
\2\Beginning in 1998, certification of reformulated gasoline
using the simple model will no longer be an option, and all
reformulated gasoline will be certified using the complex model.
Also beginning in 1998, all refiners and importers will calculate
emissions performance reductions from Clean Air Act average
gasoline; individual refiner baselines will not be relevant to
reformulated gasoline. As a result, the difficulties with downstream
enforcement and surveys will be resolved.
---------------------------------------------------------------------------
In order for the per-gallon minimums for VOC and NOX emissions
performance to be monitored by downstream regulated parties and
enforced by EPA, the baseline for a given gasoline sample must be
known. Without knowledge of the baseline, it is not possible to
determine whether the fuel complies with the per-gallon minimums, since
it will be different for each refinery. Similarly, in order for the
gasoline quality surveys to function under early use of the complex
model, the baseline from which to determine the emission performance
for VOC, toxics, and NOX must be known. Without knowledge of the
baseline, it is not possible to determine whether the complex model
fuels in an area on average meet the per-gallon standards.
EPA received comments from two industry groups representing the
refining industry on this issue. Both commenters stated that EPA should
require that ``early-use'' complex model gasolines subject to different
baselines be segregated through the gasoline distribution system. EPA
is adopting this suggested approach as the best (and perhaps only)
means of accommodating both the restricted early-use option and
downstream enforcement of per-gallon minimums and gasoline quality
surveys.
Under this approach, gasoline sampled at any point in the
distribution system would have known values for VOC, toxics, and
NOX emissions performance that meet the per-gallon and minimum
standards. Today's rule requires that these values must be included in
the product transfer documents for ``early-use'' complex model
gasoline, to inform downstream parties and EPA of the relevant per-
gallon and minimum values.
Today's rule prohibits the commingling throughout the distribution
system, including at retail outlets, of ``early-use'' complex model
gasoline that is subject to different baselines. One commenter stated
that the segregation of this gasoline should be through the terminal
level only. EPA disagrees with this comment because segregation through
the retail level also is necessary in order for gasoline quality
surveys to function. Survey samples are taken at retail outlets, and
the survey requires that the relevant per-gallon values for VOC,
toxics, and NOX emissions performance must be known for each
sample.
EPA realizes that restrictions on commingling of ``early-use''
complex model gasolines constitutes a significant constraint on the use
of this option, because most gasoline used in the United States is
transported as a fungible commodity. As a result, EPA anticipates that
before 1998 the complex model will be used only in limited situations.
This might occur where a refiner has a gasoline transportation system
that is dedicated from the refinery through the retail level, or where
the cost advantages of using the complex model are sufficiently large
to offset the difficulties of segregation. In spite of these
constraints, EPA sees no alternative to requiring segregation controls
over ``early-use'' complex model gasoline.
IV. Complex Model
The complex model described in this section has undergone
significant changes since it was first proposed in the February 1993
NPRM. These changes have been made in response to three key factors:
EPA's improved understanding of the relationship between fuel
characteristics and emissions, EPA's use of more appropriate data
analysis methods, and comments received in response to the February
NPRM, a public workshop held on May 25, 1993, and EPA's July 14, 1993
docket submission that described a number of alternative complex
models. The key elements in the complex model being promulgated today
are discussed in this section. This discussion also addresses the major
substantive comments received by EPA regarding the complex model. A
more detailed description of the model and its derivation, including a
detailed summary and analysis of comments, can be found in Section IV
of the RIA.
Baseline Emissions
As discussed in Section III, EPA is using a July 11, 1991 version
of MOBILE4.1 to estimate baseline emissions from light-duty vehicles
for the simple model, assuming a basic inspection and maintenance
program. This baseline was developed in the regulatory negotiation and
was at the time the best estimate of the in-use emission performance of
1990 vehicles from which to ensure that the minimum performance
standards required by section 211(k) of the Clean Air Act would be
achieved.
Since that time the Agency has developed a new version of the
MOBILE model, MOBILE5a, for use by the states in demonstrating
compliance with the national ambient air quality standard for ozone. As
proposed in the February 26, 1993 proposal, EPA will use MOBILE5a in
conjunction with an enhanced I/M program to establish the emission
baseline for Phase II of the reformulated gasoline program beginning in
the year 2000. EPA, however, has decided to retain the MOBILE4.1 and
basic I/M baseline assumption for the simple model during Phase I of
the RFG program. Switching to a MOBILE5a baseline for Phase I would
have required reformulated fuels to meet a slightly more stringent RVP
standard to maintain the minimum VOC emissions performance required by
the Act. The majority of the VOC emission reductions achieved by RFG
are from nonexhaust emissions; under MOBILE5a, nonexhaust VOC emission
reductions are less effective in reducing overall VOC emissions than
are exhaust VOC reductions, while the opposite is true under MOBILE4.1.
Thus, in order to provide refiners with sufficient leadtime to complete
the investments needed to meet the requirements of the program, the
baseline for the Simple Model is determined using MOBILE4.1.
When replacement of the Simple Model with the Complex Model is
required in 1998, the issue again arises as to whether a more stringent
standard should be required by shifting to use of MOBILE5a in
determining the baseline. MOBILE5a clearly provides a more recent
estimate of the mobile source VOC inventory than does MOBILE4.1.
However, many of the changes made in MOBILE5a were intended to
significantly increase the accuracy of the exhaust emission estimates
while similar changes which would have increased the accuracy of the
nonexhaust VOC emission estimate were not incorporated for various
reasons, including the limited time available to revise the MOBILE
model. As a result, the proportional contribution of exhaust and
nonexhaust VOC emissions to the in-use VOC inventory may not be any
more accurate in MOBILE5a than in MOBILE4.1 even though MOBILE5a
provides a more accurate assessment of the total contribution of mobile
sources to the entire VOC inventory by virtue of its greater accuracy
in estimating exhaust VOC emissions. Since it is the relative
proportions of exhaust and nonexhaust VOC emissions and not the overall
magnitude of the mobile source VOC inventory which determines how
difficult it will be for refiners to meet the overall VOC standard in
1998, it is unclear whether MOBILE5a would be more appropriate to use
in 1998 than MOBILE4.1.
A simple model fuel evaluated using the complex model achieves more
than the minimum 15% requirement of the Act using the MOBILE4.1
baseline exhaust/nonexhaust ratio but less than the 15% requirement
using the MOBILE5a baseline exhaust/nonexhaust ratio. Given the
uncertainty in the actual in-use exhaust/nonexhaust ratio during this
interim period, it is difficult to know whether or not the 15% actually
would be achieved in-use by a fuel meeting the requirements of the
Simple Model. Using MOBILE4.1 to determine the baseline in 1998 would
introduce some risk that the 15% minimum performance requirement of the
Act would not be met in-use by a fuel meeting the requirements of the
Simple Model. However, this risk is relatively small in magnitude (less
than three percentage points of emission reduction are at stake) and
duration (the risk exists for only two years). On the other hand, using
MOBILE5a to determine the 1998 baseline would result in some risk that
refiners would be required to incur greater costs to achieve a more
stringent standard than the minimum required by the Act. This greater
stringency would have the effect of creating a third interim phase to
the RFG program.
Given the uncertainty in determining whether a MOBILE4.1-based
performance standard or a MOBILE5a-based standard more accurately
reflects the in-use conditions in 1998, the potential disruption to
refinery operations (even if only for a small increase in the
stringency of the fuel reformulation requirements), the fact that a
more stringent standard in 1998 was not discussed or envisioned as part
of the regulatory negotiation process, and the fact that any risk to
the environment is small and of short duration, EPA does not believe it
to be appropriate to base the Phase I complex model standards on
MOBILE5a and require refiners to meet a more stringent performance
standard in 1998. As a result, EPA will retain MOBILE4.1 with basic I/M
as the basis for the Phase I performance standards under the Complex
Model in 1998.
In summary, EPA has retained the VOC and NOX baselines
proposed in the SNPRM, including the relevant I/M assumptions, for use
with the complex model prior to 2000. The onset of the Phase II
performance standards in 2000 will increase the overall stringency of
the standards, and a new baseline based on MOBILE5A will not, by
itself, be the cause of new investment by refiners. By this time,
enhanced I/M programs should be fully operational in nearly all
reformulated gasoline areas. Therefore, baseline VOC and NOX
emission levels to be used with the complex model in Phase II are based
on MOBILE5A's estimate of emissions from light-duty vehicles and trucks
with enhanced I/M.
Baseline estimates of toxics emissions are not available directly
from the MOBILE models. The nonexhaust toxics model bases its estimates
of nonexhaust toxics on the RVP and benzene levels of the fuel. Since
both of these levels are specified for Clean Air Act baseline (CAAB)
gasoline, EPA has used the nonexhaust toxics model to determine the
baseline nonexhaust toxics emission level. The exhaust toxics baseline
has been estimated by multiplying the exhaust toxics emission level
predicted by the complex model for CAAB gasoline by the ratio of
baseline exhaust VOC emissions to the average exhaust VOC emission
measurement in the complex model database. Since the five regulated
exhaust toxic pollutants are all classified as VOCs, this adjustment
sets the baseline exhaust toxics level equal to the exhaust toxics
levels that would have been observed if the vehicles represented by the
complex model database had VOC emission levels representative of in-use
vehicles when tested on CAAB gasoline. No comments were received
opposing this approach, which is discussed in more detail in Section
III of the RIA.
In evaluating the performance of simple model fuels, EPA has
focused its attention on the average refiner. The need to compensate
for differences between individual refinery baselines and the Clean Air
Act baseline when the use of the complex model becomes mandatory has
been communicated in past proposals, workshops, and the discussions
associated with the Agreement in Principle. Hence refiners have been
given adequate notice that if their baseline fuel produces higher
emissions than CAAB fuel, then they must offset such emissions when the
use of the complex model becomes mandatory in 1998. The four years
before use of the complex model becomes mandatory is adequate leadtime
for refiners. Refiners undertaking investments to comply with the
simple model requirements have been made aware of these requirements,
and this transition process was inherent in the regulatory negotiation
agreement and in prior proposals. EPA recognizes that the precise
emissions impact of individual refiner baselines could not be
determined with confidence until the Complex Model was promulgated.
However, refiners were aware of at least one course of action that
would satisfy the requirements of the program under the complex model,
namely to alter their baseline fuel to match the Clean Air Act baseline
prior to meeting the simple model requirements.
Baseline emissions of VOC, NOx, and toxics are given in Table
IV-1 for Phase I and in Table IV-2 for Phase II. Summer and winter
baselines are shown for both phases, with summer baseline emissions for
VOC Control Regions 1 and 2 shown separately. The toxics emission
baseline shown in Table IV-1 is applicable only during 1998 and 1999
and for those refiners choosing to use the complex model prior to 1998;
the baselines shown in Table IV-2 are applicable in 2000 and beyond.
Table IV-1.--Phase I Baseline Emissions, Milligrams/Mile
------------------------------------------------------------------------
Summer
Pollutant --------------------------------------
Region 1 Region 2 Winter
------------------------------------------------------------------------
Running loss VOC................. 430.77 390.42 0.00
Hot soak VOC..................... 264.61 229.96 0.00
Diurnal VOC...................... 125.09 108.71 0.00
Refueling VOC.................... 40.01 40.01 0.00
------------------------------------------------------------------------
Nonexhaust VOC................... 860.48 769.10 0.00
Exhaust VOC...................... 446.00 446.00 660.00
Total VOC........................ 1306.48 1215.10 660.00
NOx.............................. 660.00 660.00 750.00
Running loss benzene............. 4.92 4.46 0.00
Hot soak benzene................. 3.02 2.63 0.00
Diurnal benzene.................. 1.30 1.13 0.00
Refueling benzene................ 0.42 0.42 0.00
------------------------------------------------------------------------
Nonexhaust toxics................ 9.66 8.63 0.00
Exhaust benzene.................. 26.10 26.10 37.57
Acetaldehyde..................... 2.19 2.19 3.57
Formaldehyde..................... 4.85 4.85 7.73
1,3-butadiene.................... 4.31 4.31 7.27
POM.............................. 1.50 1.50 2.21
------------------------------------------------------------------------
Exhaust toxics................... 38.95 38.95 58.36
Total toxics................. 48.61 47.58 58.36
------------------------------------------------------------------------
Table IV-1.--Phase II Baseline Emissions, Milligrams/Mile
------------------------------------------------------------------------
Summer
Pollutant --------------------------------------
Region 1 Region 2 Winter
------------------------------------------------------------------------
Running loss VOC................. 328.53 294.15 0.00
Hot soak VOC..................... 84.11 80.97 0.00
Diurnal VOC...................... 93.34 63.62 0.00
Refueling VOC.................... 53.33 53.33 0.00
------------------------------------------------------------------------
Nonexhaust VOC................... 559.31 492.07 0.00
Exhaust VOC...................... 907.00 907.00 1341.00
Total VOC.................... 1306.48 1215.10 1341.00
NOX.............................. 1340.00 1340.00 1540.00
Running loss benzene............. 3.75 3.36 0.00
Hot soak benzene................. 0.96 0.93 0.00
Diurnal benzene.................. 0.97 0.66 0.00
Refueling benzene................ 0.56 0.56 0.00
------------------------------------------------------------------------
Nonexhaust toxics................ 6.24 5.51 0.00
Exhaust benzene.................. 53.54 53.54 77.62
Acetaldehyde..................... 4.44 4.44 7.25
Formaldehyde..................... 9.70 9.70 15.34
1,3-butadiene.................... 9.38 9.38 15.84
POM.............................. 3.04 3.04 4.50
------------------------------------------------------------------------
Exhaust toxics................... 80.10 80.10 120.55
Total toxics................. 86.34 85.61 120.55
------------------------------------------------------------------------
Exhaust Emissions Model
1. Data Sources
The relationship between fuel properties and exhaust emissions is
complex and the theory behind such relationships continues to be
developed. As a result, EPA has asked industry, state regulatory
agencies, and other organizations with relevant test data to make their
data available to the Agency to ensure that this rule is based on as
much relevant information as possible. The complex model described in
the following section is based on data generated from a number of
exhaust emissions testing programs. These programs, their design
intent, and their limitations are discussed in Section IV.A of the RIA.
Data from these programs were excluded from EPA's analysis if the data
were not based on a valid FTP measurement cycle, if the vehicle in
question did not employ 1990-equivalent emission control technology, if
the vehicles did not exhibit stable, repeatable emissions performance,
or if the data were clearly inconsistent with the bulk of the data
available to EPA (based on statistical considerations). In addition,
data from programs that did not measure nonmethane hydrocarbon
emissions were not used to develop EPA's exhaust VOC complex model. The
Agency believes its analysis considered all valid, and relevant data on
the exhaust emissions effect of fuel modifications when used in 1990
model year and equivalent vehicles that was available at the time the
model was developed.
2. Analysis Method
Exhaust emissions are affected by both vehicle and fuel
characteristics. Since the test programs described above generally
involved different vehicles, different fuels, and in some cases
different test procedures, the analysis required to determine the
relationship between fuel properties and emissions is complex. However,
EPA believes that the methods used to develop the complex model
considers and addresses these complexities appropriately. EPA utilized
statistical analysis techniques to isolate the effects of fuel
modifications on exhaust emissions of VOC, NOX, and toxics from
other factors affecting exhaust emissions.
At a series of six public workshops held over the past two years,
the Agency presented its views on data sources, analysis methods, and
preliminary emissions models for public review and comment. The Agency
also requested other organizations to share their data, analysis
expertise, and emissions models at these workshops. The methods used to
develop the model promulgated today appropriately incorporate the
comments and suggestions regarding the analysis process received at the
workshops, as well as other comments and suggestions received from
industry, state and federal government authorities, and other
interested parties during the course of this rulemaking. Information
regarding the workshops, public comments and suggestions, and EPA's
analysis methods can be found in Docket A-92-12. The approach chosen by
EPA to analyze the available data is summarized below and is discussed
more fully in Section IV.A of the RIA.
Since the vehicle and the fuel both affect exhaust emissions, EPA's
analysis separated exhaust emissions into fuel components and vehicle
components. In all test programs analyzed by EPA, the single most
significant determinant of the level of emissions from a given vehicle
on a given fuel was the vehicle itself. Fuel properties exert a much
smaller influence on exhaust emissions than do vehicle characteristics
such as emission control system technology, vehicle mileage, catalyst
efficiency, oxygen sensor efficiency, engine size, engine design,
vehicle size, fuel efficiency, vehicle maintenance, etc. To identify
the effects of fuel property modifications on emissions, EPA found it
necessary to identify the effect of each vehicle on emissions and
separate this effect from the fuel effects. For vehicles used in more
than one test program, EPA found it necessary to determine the vehicle
effect separately for each test program since vehicle effects were
observed to change between studies.
The fuel components of exhaust emissions were separated into two
main categories. The first category consisted of the effects of
individual fuel parameters. For example, the effect of sulfur on
NOX emissions was best modeled by a relationship containing a
linear sulfur term (of the form c1S, where c1 is a constant
and S is the sulfur level) and a second-order sulfur term (of the form
c2S2, where c2 is a constant). The second category of
fuel terms consisted of interactive effects between two fuel
parameters. For example, EPA's analysis found that the effect of
aromatics on hydrocarbon emissions is related to the E300 level of the
fuel. This effect cannot be represented as an aromatics or E300 effect
alone but must be represented as an interactive term of the form
c3AE, where c3 is a constant, A is the aromatics level, and E
is the E300 level.
In the February 1993 proposal, EPA indicated that it planned to
make several changes to the method used to develop the complex model.
As discussed in that proposal and in the RIA, fuels can be
characterized in terms of a number of different sets of fuel
parameters. EPA used the results of individual fuel studies and its
public workshops to select the set of fuel parameters used to model
exhaust emissions in its February 1993 proposal. At that time, the
Agency indicated that it might alter its choice of parameters to
represent gasoline distillation characteristics from a temperature
basis (using T50 and T90) to a percent evaporated basis (using E200 and
E300, the percentage of the fuel's volume that evaporates when heated
to 200 deg.F and 300 deg.F, respectively). For reasons outlined in the
February 1993 NPRM and section IV.A of the RIA, EPA has chosen to make
this change and has converted its exhaust emission models to a percent
evaporated basis since the NPRM was issued, removing the T50 and T90
terms from its models in the process. The Auto/Oil Heavy Hydrocarbon
and EPA Phase II Reformulated Gasoline Test Program studies have been
added to the complex model database. Finally, EPA has changed the
confidence level required to permit terms to remain in the model to 90
percent, in keeping with the approach used in developing the simple
model. The Agency was not able to determine the influence of the type
of aromatic compounds in fuels, specifically heavy aromatics, on
exhaust emissions, and hence such terms have not been included in the
complex model at this time.
Because vehicles can have different emission control systems, the
Agency anticipated that fuel modifications would have different
emission effects on different types of cars. To account for these
differences, EPA's February 1993 proposal divided vehicles into two
``emitter classes'' (normal and higher emitters) based on their exhaust
emission levels. EPA then subdivided vehicles in each emitter class
into ``technology groups'' based on the emission control technology
with which each vehicle was equipped. However, as discussed in the
NPRM, EPA was concerned that technology group distinctions among higher
emitters might not be appropriate, since such vehicles' high level of
emissions indicated that their emission control systems were not
functioning properly. In addition, the limited quantity of data for
higher emitters made it difficult to identify genuine differences in
emissions response between higher emitters of different technology
groups. Many commenters expressed similar concerns. Hence the model
promulgated today does not divide higher emitters into technology group
categories but retains such distinctions when analyzing normal
emitters. In response to numerous comments, EPA attempted to reduce the
number of normal emitter technology groups. However, as discussed in
section IV.A of the RIA, EPA was unable to identify an appropriate
basis for consolidation. EPA considers its retention of emitter class
and technology group distinctions to be justified by the presence of
statistically significant fuel effects specific to individual emitter
classes and technology groups in today's complex model.
At the same time, EPA recognized the validity of comments received
from a number of sources that (1) many emission effects were likely to
be consistent across multiple technology groups or across emitter
classes, and (2) insufficient data were available to model many
potential terms, particularly interactive terms. The approach used by
EPA to construct the complex model proposed in February 1993 did not
incorporate these legitimate concerns. To do so, EPA has utilized a
modified version of the ``unified'' approach advocated by API and other
commenters (as described in the RIA) to develop today's complex model.
This modeling approach, the statistical criteria used by EPA in
conjunction with this approach, and the techniques used to simplify the
models are discussed in detail in section IV.A of the RIA and are
summarized below.
First, interactive terms were permitted to enter the models only
when sufficient data were available. The model proposed in the February
1993 NPRM permitted all interactive terms to enter the models,
regardless of whether sufficient data were available to estimate such
an effect, and it did not apply statistical criteria to evaluate
whether terms added to the model introduced more risk of inaccuracy in
the model than they removed.
Second, preliminary models for higher emitting vehicles were
constructed based solely on data from such vehicles. Only those terms
that satisfied EPA's statistical criteria (discussed at length in the
RIA) were retained. These criteria included measures to balance
overfitting (introducing too many terms to explain the observed data)
and underfitting (not including terms necessary to explain the observed
data). The NPRM model did not include measures to prevent overfitting.
Third, the entire database was analyzed using the unified approach.
The effects of each term on emissions was divided into two parts: an
average effect across all vehicles, and a series of adjustment terms
for each technology group and for higher emitters. Only those terms
that satisfied EPA's statistical criteria were retained, with two
exceptions. Higher emitter adjustment terms were retained regardless of
statistical significance since they had been found to be statistically
significant when examining the higher emitter data separately. EPA was
concerned that failure to do so might cause genuine higher emitter
effects to be ``washed out'' by the greater number of data for normal
emitters. In addition, some overall terms were retained for hierarchy
reasons despite low statistical significance. For example, a linear
term for a given fuel parameter (e.g., E300) might not be significant
while a squared term for the same parameter (e.g., E300\2\) might be
significant. Since the mathematical form of the squared terms includes
the corresponding linear effects, the linear term would be retained
regardless of significance to preserve the model's hierarchical
structure. The importance of hierarchy was emphasized by a number of
workshop participants and commenters, as discussed in the RIA. The NPRM
model included separate terms for each technology group and emitter
class and hence did not include terms to represent the average effect
of a fuel parameter across all vehicles. The NPRM model also did not
incorporate hierarchy considerations.
Fourth, outlying and overly influential data were dropped from the
database and the model was re-estimated based on the remaining data.
Outlying data consist of observations that differ from the average
observed effect by so large a margin that they are more likely to
represent observational error, reporting error, or other measurement
artifacts than genuine phenomena. Outlying data can obscure genuine
emissions effects. Influential data consist of observations that by
themselves materially affect the resulting model, i.e., the model would
differ materially if they were excluded. In a database the size of the
Complex Model database, individual data points should not have such
unusually large effects. Excluding outlying and influential
observations is standard statistical practice. The NPRM model did not
exclude either type of observation.
Fifth, terms were deleted from the resulting model to avoid
overfitting and collinearity problems. Overfitting occurs when so many
terms are included in a regression model that the expected error due to
the erroneous inclusion of a term exceeds the expected error due to not
including the term. Collinearity problems occur when the fuel
parameters included in the model are correlated with one another in the
fuels tested. For example, the addition of oxygenate to gasoline causes
E200 to increase. The oxygenate-containing fuels in the complex model
database tend to have higher E200 values than fuels without oxygenate.
In a sense, one can predict the E200 value of a fuel by knowing its
oxygen content. Hence these two parameters would be considered to be
highly collinear. Since regression models are developed under the
assumption that terms are not collinear, the presence of strong
collinearities can introduce error into the regression. Today's complex
model takes both collinearity and overfitting into account by using a
standard statistical criterion called Mallow's Cp criterion to
remove terms which introduce large overfitting and collinearity
problems. This approach resulted in a simpler, more reasonable, and
statistically more sound model than had been proposed in the February
1993 NPRM. It should be noted that high emitter terms forced into the
model earlier in the process could be dropped at this stage of the
analysis. Measures were taken to limit collinearity problems in the
NPRM model, but overfitting concerns and the Cp criterion were not
addressed.
Sixth, the contribution of each remaining term to the model's
explanatory power was estimated, and those terms whose contribution
summed to less than one percent were deleted (i.e., the retained terms
accounted for 99 percent of the explanatory power of the model) to
simplify the form of the model without materially reducing its ability
to predict the emissions impact of fuel modifications. This step was
not taken during development of the NPRM model.
Finally, the resulting models for each technology group within the
set of normal emitting vehicles were consolidated into a single
equation using a random balance approximation. The details of that
approximation are given in Section IV.A of the RIA. This step was not
taken during development of the NPRM model.
The results of EPA's modeling efforts confirms the importance of
technology group and emitter class distinctions, as can be seen by
examining the differences in the exhaust emission equations for
specific normal emitter technology groups or for normal and higher
emitter class categories (as discussed in greater detail in the RIA).
Efforts to reduce the number of technology group categories for normal
emitters were not successful. Efforts to subdivide higher emitters by
their emission characteristics such as exhaust hydrocarbon to NOX
ratio did not improve the quality of EPA's higher emitter model.
However, as discussed above, EPA found it unnecessary to separate
higher emitters by technology group. This modification reflects EPA's
belief, supported by preliminary field information, that one or more
emission control components on higher emitters tend to be
malfunctioning, which renders a classification scheme based on vehicle
equipment questionable.
3. Exhaust Model
As was discussed in the April 1992 and February 1993 proposals, the
weight assigned to each technology group or emitter class for modeling
purposes was set equal to its contribution to in-use emissions for each
pollutant. The weight assigned to each emitter class was set equal to
its projected contribution to in-use emissions. The weighting factor
assigned to normal emitters was then broken down further by technology
group, again according to their projected contribution to in-use
emissions. These estimates and projections are essentially unchanged
from the February 1993 proposal, although minor changes have been made
to reflect more complete information about the fraction of 1990 sales
accounted for by each technology group. The rationale for, derivation
of, and renormalization of the weighting factors themselves are
discussed in more detail in the RIA.
Various commenters indicated that they considered EPA's previously
proposed models were too complex. In response, the Agency has modified
its analysis method in several ways. The resulting method, described in
Section IV.B.2, results in exhaust emission models containing two
equations for each pollutant instead of as many as sixteen separate
equations, as was the case for the model proposed in February 1993.
Each equation also has far fewer terms than the February 1993
equations. However, EPA does not believe that today's less complicated
complex model is less accurate than the complex models presented at
public workshops or in the February proposal. This belief is based on
the models' comparable explanatory power (as reflected in their similar
R\2\) and the superior accuracy of today's model in accounting for the
emission effects seen in the vehicle testing programs that comprise the
complex model database. Today's VOC and NOX models are based on
the most accurate of the three sets of models included in EPA's July
14, 1993 docket submittal, while also taking into account relevant
comments regarding specific aspects of the models. Today's toxics
models are a further simplification of the models included in the July
1993 docket submittal in response to comments received by EPA on its
docket submittal. These points are discussed more fully in Section IV.A
of the RIA.
The specific equations that comprise the complex model can be found
in section 80.45 of the regulations for this rule. Their derivation is
discussed in detail in Section IV.A of the RIA. The range of parameter
values for which these equations are valid is discussed in Section D
and in Section IV.D of the RIA. As discussed in Section V, refiners are
required to submit data to augment the model if they wish to certify
fuels with properties that fall outside this range as reformulated
gasolines.
C. Nonexhaust Model
Nonexhaust emissions are less strongly affected by vehicle design
and are influenced by fewer fuel characteristics than are exhaust
emissions. In addition, the theoretical principles involved in
nonexhaust emissions (which include evaporative, running loss, and
refueling emissions) are better understood, and nonexhaust emission
control technologies are more consistent across vehicles, than are
exhaust emissions and emission control technologies. Since the
relationship between fuel properties and nonexhaust emissions is less
complex and better understood than for exhaust emissions, there was
much less need for EPA to generate additional data to evaluate
nonexhaust emissions than was the case for exhaust emissions. EPA was
able to base its nonexhaust VOC emission model on data generated from
EPA's ongoing nonexhaust emissions testing program that has been used
to develop EPA's MOBILE emission inventory models, specifically the
MOBILE4.1 and MOBILE5.0A models. EPA believes this data to be
sufficient to model the relationship between fuel properties and
nonexhaust VOC emissions for the purposes of this rule. Additional
information about MOBIL4.1 and MOBILE5.0A can be found in Dockets A-91-
02 and A-92-12.
EPA is in the process of developing an enhanced model of nonexhaust
VOC emissions, based on a more complete set of theoretical principles
and additional test data, that is expected to be more accurate and more
widely applicable to oxygenated fuels than the MOBILE models. A
preliminary version of this model was discussed at a public workshop
held on August 25, 1992, and materials related to this model have been
placed in the docket for this rulemaking. At this time, however, this
enhanced nonexhaust VOC emissions model is not complete and hence is
not incorporated in today's complex model.
The nonexhaust VOC model in today's complex model is based on
correlations between RVP and nonexhaust VOC emissions derived from the
July 11, 1991 version of MOBILE4.1 for Phase I of the reformulated
gasoline program (1995-1999) and from MOBILE5A for Phase II (2000 and
beyond). This approach is consistent with the definition of baseline
emissions set forth in Section IV.A and is based on the same
considerations outlined in that section.
To develop the correlations shown below, the MOBILE models were
used with temperatures of 69 to 94 degrees Fahrenheit for Class B areas
and 72 to 92 degrees Fahrenheit for Class C areas. As discussed in
Section IV.A, a basic inspection and maintenance program was assumed
for Phase I while an enhanced I/M program was assumed for Phase II. In
addition, the presence of Stage II evaporative emissions recovery
systems with an overall vapor recovery efficiency of 86 percent was
assumed (as discussed in the SNPRM and NPRM). EPA is in the process of
promulgating requirements for onboard refueling emission controls which
may be more effective at controlling refueling emissions than Stage II
vapor recovery systems. However, these requirements did not apply to
1990 model year vehicles and hence cannot be incorporated into the
model for certification purposes. In addition, EPA has chosen not to
incorporate the effects of onboard refueling controls in its evaluation
of the effects of reformulated fuels on emissions from the entire in-
use vehicle fleet, which includes vehicles from a number of different
model years. This decision was made for several reasons. First,
requirements for onboard refueling controls have not yet been
finalized, making evaluation of their impact on in-use emissions
difficult. Second, onboard refueling controls are not expected to be
required on all new vehicles until 2000 and are not expected to be
present on the bulk of in-use vehicles for several years after that
time. Third, while onboard controls are expected to be more efficient
at controlling refueling emissions than Stage II controls, the
difference is not expected to be large in areas affected by the
reformulated gasoline program and will affect only a small portion of
total nonexhaust VOC emissions. Since EPA's analysis of the additional
benefits of onboard vapor recovery controls is not yet available, and
since such benefits are expected to be small relative to overall
emissions, EPA has chosen to retain its assumptions regarding Stage II
vapor recovery in forecasting the effects of fuel modifications on
nonexhaust VOC emissions from the in-use vehicle fleet.
The only toxic air pollutant covered by the reformulated gasoline
program that is found in nonexhaust emissions is benzene, which is a
natural component of gasoline. The other four toxic air pollutants
listed in section 211(k) are solely products of fuel combustion and
hence are not found nonexhaust emissions. As discussed in the SNPRM,
the Agency's correlation between fuel benzene content and summer non-
exhaust benzene emissions is based on results from General Motors'
proprietary model of tank vapors, as confirmed independently by EPA-
generated data using a number of fuels. Both the derivation and
verification of the non-exhaust benzene emissions model are discussed
more fully in the RIA. The nonexhaust benzene emission model also
depends on the RVP of the fuel, as is the case for the nonexhaust VOC
emission model. The derivation of the nonexhaust benzene and VOC models
is discussed more fully in the RIA.
D. Range/Extrapolation
Like all regression models, the complex model is not valid for all
possible input values. The range of fuel parameter values over which
the complex model accurately predicts vehicle emissions is given in
Table IV-3. These ranges are based on the range of data used to develop
the models and on comments received by the Agency on this issue. The
limits proposed in the February 1993 were, in some cases, narrower than
the range of data used to develop the complex model. In addition, the
limits proposed in the NPRM would have prevented a number of very low
emitting fuels from being certified using the model.
Table IV-3.--Parameter Ranges for Which the Complex Model Can Be Used
------------------------------------------------------------------------
Valid range for:
---------------------------
Fuel Parameter Reformulated Conventional
fuel fuel
------------------------------------------------------------------------
Aromatics, vol %............................ 0-50 0-55
E200, %..................................... 30-70 30-70
E300, %..................................... 70-100 70-100
Olefins, vol %.............................. 0-25 0-30
Oxygen, vol %............................... 0-3.7 0-3.7
RVP, psi.................................... 6.4-10 6.4-11
Sulfur, ppm................................. 0-500 0-1000
Benzene, vol %.............................. 0-2.0 0-4.9
------------------------------------------------------------------------
EPA has received a number of comments requesting alterations in the
model's range. After considering these comments and re-evaluating the
data on which the complex model is based, EPA has modified the range
limits. In some cases, EPA has chosen to extrapolate the complex model
slightly beyond the range for which data were available in order to
allow additional fuels, both conventional and reformulated, to be
evaluated using the model without recourse to expensive and time-
consuming vehicle testing. These extrapolations are limited to those
parameters whose effects appear to be well-characterized by the complex
model. A detailed discussion of the limits of the available data, EPA's
rationale for extending the valid range of the model for some
parameters, and the extrapolation method used to extend the model can
be found in Section IV.D of the RIA.
E. Winter
While the VOC performance standard for reformulated fuels applies
only in the summer, the toxics and no-NOx-increase requirements
apply year-round. EPA therefore recognized the need to model the
exhaust toxics and NOx emissions performance of reformulated
gasolines during the winter months as well as during the high ozone
season. Modeling winter emissions performance, however, presented a
number of difficulties. First, the data sources described earlier
provided data on emissions performance only under summer conditions and
for gasolines with RVP levels typical of summer gasolines. Second, the
RVP levels of fuels included in the complex model database ranged from
7 to 10 psi, while winter fuels tend to have RVP levels in the 11.5 psi
range and are not restricted by other regulations. Hence the complex
model cannot be used directly for fuels with typical winter RVP levels.
RVP's impact on canister loading and subsequent purging is thought
to be the primary cause of its effects on exhaust emissions. Since data
do not exist on the effects of winter fuels on canister loading under
winter conditions, the Agency is not able at this time to model the
effects of winter RVP levels on exhaust emissions. To avoid making
unsound or speculative predictions, EPA proposed and is now
promulgating a requirement that for purposes of evaluating emissions
effects using the complex model, the RVP of winter fuels be set at the
summer statutory baseline RVP value. In effect, this requirement builds
into the model the assumption that the RVP level of winter gasolines
has no effect on NOx or exhaust toxics emissions. As a result,
refiners will not be required to alter the RVP levels of winter
gasolines. Refiners will receive neither benefit nor penalty for
changing the RVP of their winter gasolines. To evaluate winter fuels
using the complex model, an RVP value equal to that of summer baseline
gasoline (8.7 psi) must be used instead of the fuel's actual RVP. Doing
so effectively removes the contribution of RVP to winter exhaust
emissions.
When sufficient data is developed on the emissions impact of winter
RVP levels under winter ambient conditions, EPA will be able to revise
the complex model accordingly. Until then, EPA believes it is more
appropriate to assume that RVP levels have winter exhaust emission
effects than to speculate about the magnitude of such impacts.
In its prior proposals, EPA had proposed that winter nonexhaust
emissions, including winter nonexhaust benzene emissions, be considered
zero. EPA received a number of comments requesting that both baseline
emissions and the nonexhaust toxics model include winter nonexhaust
benzene emissions. This request was based on the belief that the year-
round benzene limits would result in reduced nonexhaust benzene
emissions in the winter months. EPA has evaluated this claim, taking
into account temperature ranges and the effects of inspection and
maintenance programs on such emissions. EPA acknowledges the validity
of this claim, since winter nonexhaust emissions, including nonexhaust
benzene emissions, are likely to be nonzero under all winter
temperature ranges. In the past, the lack of sufficient data on
nonexhaust emissions under winter temperature conditions has prevented
EPA from developing reliable, accurate models of winter nonexhaust
emissions. The commenters provided a limited quantity of data on winter
nonexhaust emissions to support their claim. However, the data
submitted in support of this claim were based on measurements of
nonexhaust emissions from vehicles with very low nonexhaust emissions.
EPA's analysis indicates that these vehicles are not representative of
in-use vehicles. In addition, the chemical composition of the measured
nonexhaust emissions were characteristic of resting losses (losses that
occur due to permeation through fuel system components) rather than of
diurnal, hot soak, or running loss emissions. Resting losses are not
included in EPA's baseline emission estimates, so EPA does not consider
it appropriate to include resting losses in its nonexhaust emission
models. Finally, no data were submitted on nonexhaust benzene emissions
from fail vehicles under winter conditions. Since nonexhaust benzene
emissions from such vehicles will comprise a significant portion of
winter nonexhaust benzene emissions, EPA is concerned that a model
based on the submitted data would not provide accurate estimates of
such emissions. Given the theoretical merits of the claim, however, EPA
will consider including a model of winter benzene nonexhaust emissions
in the complex model in the future when sufficient data become
available.
F. Fungibility
EPA has long recognized the importance of maintaining a fungible
fuel system, in which complying gasolines can be mixed freely without
resulting in mixtures that do not themselves comply with regulatory
requirements. Fungibility is essential to smooth, cost-effective
operation of fuel distribution systems such as pipelines. The Agency
has received numerous comments on the need to maintain fungibility. At
the same time, the Agency considers it essential that gasolines
certified as reformulated meet all required emission performance levels
in the field. In cases where the effects of a given fuel parameter on
emissions are non-linear, it is possible for two complying fuels to
produce a non-complying fuel when mixed.
The complex model contains a number of nonlinear terms, which
introduces the possibility that gasolines which comply with this rule's
requirements in isolation would not comply if mixed with other
complying fuels. EPA has been concerned with this possibility and has
undertaken extensive analyses to determine its likelihood and to
develop methods to cope with its occurrence. EPA's analyses, which have
utilized methods that have been supported by a number of organizations,
indicate that the complex model promulgated in today's rule will not
create fungibility problems despite its inclusion of nonlinear terms.
This analysis is explained in greater detail in Section IV.F of the
RIA.
G. Future Model Revisions
The complex model promulgated in this rulemaking reflects EPA's
best understanding of the relationship between fuel characteristics and
vehicle emissions. However, EPA expects future research to clarify this
relationship. EPA also recognizes that changes in in-use vehicle
emission control programs (e.g., I/M programs) will continue to occur
and that these changes may alter the relationship between fuel
characteristics and in-use emissions. In addition, the Agency is
concerned that augmentations to the model through vehicle testing
(Section V) may, over time, accumulate to the point that a revised
complex model, incorporating the current complex model database and all
relevant information gathered since then, would be beneficial. As
discussed in Section V, EPA plans to issue revised complex models when
the Agency deems that sufficient new information is available to
warrant such action. Model revisions will be developed through a formal
rulemaking process.
H. Complex Model Performance of Simple Model Fuels
Fuels qualifying as reformulated under the simple model must meet
specified benzene, oxygen, and RVP requirements while also satisfying
the toxics performance standard. The RVP requirement differs between
VOC control regions, and the requirements and standards also vary
depending on whether compliance is being achieved on a per-gallon or
averaging basis. In addition, levels of other fuel parameters are only
specified under the simple model in terms of deviations from each
refiner's baseline fuel. Evaluating the performance of simple model
fuels under the complex model is difficult since fuel properties can
vary widely.
However, it is possible to evaluate a set of fuels that are
representative of expected, typical simple model fuels. EPA expects
most refiners to pursue compliance on average (for all or part of their
product slate) in order to maximize flexibility in day-to-day refinery
operations and recoup compliance margins. Given present and projected
conditions, EPA also expects that MTBE and ethanol will be the most
commonly used oxygenates during Phase I of the reformulated gasoline
program. The fuels specified in Tables IV-4 and IV-5 below include
fuels designed to meet the requirements of the simple model in both VOC
control regions and using both oxygenates. The level of olefins,
sulfur, E200, and E300 have been set to Clean Air Act baseline levels,
while the level of aromatics has been set at the level necessary to
comply with the toxics requirements of the simple model. Aromatics
levels were assumed to be the same for summer and winter fuels.
Table IV-4.--Typical Simple Model Fuels Using MTBE
[Under Averaging]
------------------------------------------------------------------------
Fuel
-------------------------------------------------------
1 2 3 4
------------------------------------------------------------------------
Fuel
Description:
Season........ Summer...... Summer...... Winter...... Winter
VOC Control 1........... 2........... 1........... 2
Region.
Fuel
Parameter:.
RVP, psi...... 7.1......... 8.0......... N/A......... N/A
Oxygen, wt%... 2.1......... 2.1......... 2.1......... 2.1
Benzene, vol%. 0.95........ 0.95........ 0.95........ 0.95
Aromatics, 27.5........ 26.3........ 27.5........ 26.3
vol%.
Olefins, vol%. 9.2......... 9.2......... 11.9........ 11.9
E200, %....... 41.......... 41.......... 50.......... 50
E300, %....... 83.......... 83.......... 83.......... 83
Sulfur, ppm... 339......... 339......... 338......... 338
------------------------------------------------------------------------
Table IV-5.--Typical Simple Model Fuels Using Ethanol
[Under Averaging]
------------------------------------------------------------------------
Fuel
-------------------------------------------------------
5 6 7 8
------------------------------------------------------------------------
Fuel
Description:
Season........ Summer...... Summer...... Winter...... Winter
VOC Control 1........... 2........... 1........... 2
Region.
Fuel
Parameter:.
RVP, psi...... 7.1......... 8.0......... N/A......... N/A
Oxygen, wt%... 2.1......... 2.1......... 2.1......... 2.1
Benzene, vol%. 0.95........ 0.95........ 0.95........ 0.95
Aromatics, 25.5........ 24.3........ 25.5........ 24.3
vol%.
Olefins, vol%. 9.2......... 9.2......... 11.9........ 11.9
E200, %....... 41.......... 41.......... 50.......... 41
E300, %....... 83.......... 83.......... 83.......... 83
Sulfur, ppm... 339......... 339......... 338......... 338
------------------------------------------------------------------------
The performance of these fuels according to the complex model
(using the MOBILE4.1 baseline as previously discussed) is summarized in
Table IV-6.
Table IV-6.--Performance of Typical Simple Model Fuels Under the Phase I Complex Model
[Under Averaging]\1\
----------------------------------------------------------------------------------------------------------------
Emission reduction versus CAAB fuel (percent)
----------------------------------------------------------------
Fuel Nonexhaust
Exhaust VOC VOC Total VOC NO X Toxics
----------------------------------------------------------------------------------------------------------------
1.............................................. 7.92 51.42 36.57 1.46 27.33
2.............................................. 5.35 23.93 17.11 1.28 24.57
3.............................................. 0.33 N/A 0.33 -0.21 12.83
4.............................................. 0.80 0.00 0.80 0.04 13.87
5.............................................. 8.64 51.42 36.82 1.90 25.70
6.............................................. 6.09 23.93 17.38 1.76 22.56
7.............................................. 3.55 N/A 3.56 0.58 11.52
8.............................................. 4.01 N/A 4.01 0.88 12.48
----------------------------------------------------------------------------------------------------------------
\1\Performance of summer fuels (#s 1, 2, 5, 6) given relative to that of Clean Air Act summer baseline fuel.
Performance of winter fuels (#s 3, 4, 7, 8) given relative to that of the winter baseline fuel defined in
Section III.
I. Phase I Performance Standards Under the Complex Model
All fuels produced during Phase I of the reformulated gasoline
program must meet the VOC, toxics, and NOX requirements of the
Act. Fuels certified using the complex model in Phase I must show
either no increase in NOX emissions from baseline levels on a per-
gallon basis as discussed in the February 1993 proposal or a 1.5%
reduction from baseline levels on average as discussed in Section VII.
In addition, as discussed in Section III.E., such fuels must result in
either a 15% reduction in total toxics emissions from baseline levels
on a per-gallon basis or a 16.5% reduction in total toxics emissions
from baseline levels on average.
With regard to the VOC standards, EPA considers fuels produced to
meet the provisions of the simple model to be producible. Thus, as
discussed in the February 1993 proposal, EPA believes it feasible to
base the Phase I standards for VOC emissions on the performance of
fuels that meet the Simple Model requirements, provided that this
performance is more stringent than minimum performance required by the
Act. EPA considers the fuels whose VOC performances were evaluated in
Section IV.H to be representative of Simple Model fuels. Under the
reformulated gasoline program, VOC emissions are controlled only during
the high ozone season. For this reason, the VOC performance standard
has been determined by the performance of the Phase I summer fuels
presented in Section IV.H. Since these fuels achieve emissons
reductions that equal or exceed the minimum requirements set forth in
the Act, the VOC performance standard during Phase I for fuels
certified under the complex model has been based on the performance of
these fuels. Setting the VOC performance standards in 1998-1999 equal
to this VOC performance level, which EPA believes to be a reasonable
estimate of the average performance of fuels produced in 1995-1997,
preserves the integrity of the two-phase program specified by Congress
and is consistent with the Agreement in Principle signed in 1991.
The summer VOC performance of ``typical'' high ozone season simple
model reformulated gasolines according to the complex model is
presented in Table IV-6. In VOC Control Region 1, the simple model fuel
reduces VOC emissions by 36.6 percent for the MTBE-containing fuel
(Fuel 1) and 36.8 percent for the ethanol-containing fuel (Fuel 5).
Since the 1998 performance requirements in VOC Control Region 1 are to
be based on the performance of typical simple model fuels, and since
Fuels 1 and 5 both satisfy the simple model requirements and are
considered by EPA to be representative of typical simple model fuels,
EPA has set its 1998 performance standards in VOC Control Region 1 so
as to permit both of these fuels to meet the 1998 performance
standards. In addition, EPA considers Fuel 1 to be more representative
of typical simple model fuels in VOC Control Region 1 since MTBE does
not boost fuel RVP levels to the extent that ethanol does. As was
discussed in the April 1992 and February 1993 proposals, EPA believes
that per-gallon performance standard should be set 1.5 percentage
points below the averaging performance standard. Hence high ozone
season fuels certified using the complex model during Phase I of the
reformulated gasoline program must provide a VOC emission reduction
from baseline levels of 36.6 percent when complying on average and 35.1
percent when complying on a per-gallon basis. Similarly, high ozone
season fuels certified using the complex model during Phase I in VOC
Control Region 2 must provide a VOC emission reduction from baseline
levels of 17.1 percent when complying on average and 15.6 percent when
complying on a per-gallon basis. These standards are summarized in
Table IV-7 for both VOC control regions, under averaging and per-gallon
compliance. Note that a negative performance standard signifies a
reduction from baseline emission levels.
Table IV-7.--Reformulated Gasoline Performance Standards Relative to Clean Air Act Baseline Gasoline for 1998-
1999
[Percent]
----------------------------------------------------------------------------------------------------------------
VOC control region 1 VOC control region 2
Emission ---------------------------------------------------------------
Average Per gallon Average Per gallon
----------------------------------------------------------------------------------------------------------------
VOC............................................. -36.6 -35.1 -17.1 -15.6
Toxics.......................................... -16.5 -15.0 -16.5 -15.0
NOX............................................. -1.5 0.0 -1.5 0.0
----------------------------------------------------------------------------------------------------------------
In summary, the per-gallon and averaging VOC performance standards
under the complex model during Phase I is set by the performance of the
corresponding simple model fuel when evaluated using the complex model.
The toxics performance standard is set at the statutory requirement of
a 15 percent reduction from baseline levels for per-gallon compliance
and a 16.5 percent reduction for compliance on average. Similarly, the
NOX performance standard under the complex model during Phase I
must satisfy the no NOx increase requirement on a per-gallon
basis, or meet a 1.5% reduction for compliance on average.
V. Augmenting the Models Through Testing
During the regulatory negotiation process, vehicle testing and
emission modeling procedures for certifying that a gasoline complies
with the NOX, toxics, and VOC requirements were discussed.
Emission models such as the simple model described in Section III and
the complex model described in Section IV offer several advantages over
testing to determine emission effects. First, models can better reflect
in-use emission effects since they can be based on the results of
multiple test programs. Second, individual test programs may be
intentionally or unintentionally biased due to vehicle selection, test
design, and analysis methods. Third, fuel compositions tend to vary due
in part to factors beyond the control of fuel suppliers such as
variations in crude oil compositions and the inherent variability of
refining processes. As a result, without one or more modeling options,
each batch of fuel would have to be tested to ascertain its emission
performance. Such levels of testing are neither desirable (because of
the potential for intentional or unintentional bias in vehicle test
programs) nor practical (because of the time and expense involved in
vehicle testing). Fourth, models make more efficient use of scarce and
expensive emission effects data than is possible otherwise. For these
reasons, EPA believes that the modeling options outlined above are
necessary for the reformulated gasoline program to achieve its
environmental objectives and to minimize the costs of the program.
These emission models, however, reflect currently-available
information and hence do not allow refiners to take advantage of
emission benefits derived from new fuel additives or changes in fuel
parameters not contained in the models. To allow for fuel technology
development and innovation, the Agency also believes that testing has a
role in certification as a means of supplementing the models. This
section contains a detailed discussion of the provisions EPA is
promulgating regarding the conditions under which testing is permitted,
the manner in which test results can be used to supplement the models,
and the minimum requirements for vehicle testing programs. As was first
outlined in the February 1993 NPRM, the vehicle testing process
described in this section has undergone significant changes since it
was first proposed in the April 1992 SNPRM. These changes have been
made in response to changes in EPA's approach to modeling the
relationship between fuel properties and emissions, as described in
Section IV, and comments received in response to the April 1992 and
February 1993 proposals. The following discussion addresses the major
substantive comments received by EPA regarding certification of fuels
by vehicle testing. A detailed summary and analysis of comments can be
found in Section IV.G of the RIA.
A. Applicability of Testing
Vehicle testing is the primary way that the effects of various
gasoline formulations on motor vehicle emissions can be determined. As
described above, data from vehicle testing programs forms the bulk of
the basis for the simple and complex models.
EPA believes that fuel certification through single test programs
is inherently less reliable than certification through a testing-based
model. The simple and complex models developed by EPA are based on a
far greater amount of testing than would be available from any single
test program. These models incorporate and balance the varying and
conflicting results of numerous test programs. The statistical
variation associated with an individual test program may cause a fuel
to show emission effects during testing that would not occur in-use.
Therefore, EPA proposes that testing only be permitted to augment the
models for fuel effects that are not covered in the models.
B. Augmenting the Simple Model
Due to the belief that fuels certified by vehicle testing should be
evaluated in conjunction with the most complete emission model
available to more accurately determine the emission benefits of the
fuels being tested, EPA proposed that vehicle testing be permitted to
augment the simple model only for the effect of oxygenates on NOx
emissions beyond the simple model's oxygen caps. All other testing was
to have been performed to augment the complex model. Based on data
collected since the time of the proposal on the effect of oxygenates on
NOx, EPA no longer believes it appropriate to augment the simple
model even in the limited manner described above. Considerably more
data are available in the complex model database regarding the effect
of oxygenates on NOx emissions than would be provided by any
individual test program. Therefore, testing can only be performed to
augment the complex model. Fuels with oxygen concentrations in excess
of 2.7 weight percent must be certified using the complex model.
C. Augmenting the Complex Model
EPA believes that the objective of testing under the complex model
should be to evaluate the emission effects of fuels whose emission
effects cannot be adequately represented by the model. Such fuels would
include fuels claiming emission effects from parameters not included in
the complex model and fuels containing complex model parameters at
levels beyond the range covered by the model. Without this constraint,
it may be possible for a fuel producer to use the statistical variation
associated with testing to claim emission effects through testing which
would not be demonstrated in-use, when tested to a greater degree, or
when modeled. For example, a fuel that would fail to meet the VOC
requirement by a small margin when evaluated under the complex model
could be tested and shown to meet the VOC requirement due to the
testing error associated with any vehicle testing program. In addition,
allowing testing of existing modeled parameters essentially would make
the complex model, and the associated emission performance standards, a
fluid target. Fuel producers would lose the certainty associated with a
fixed model and the confidence that their capital investments will be
useful for a fixed amount of time. Therefore, vehicle testing can be
used only to determine the emission effects of parameters not
adequately represented by the complex model. The emission effects of
the fuel parameter in question will be determined by combining the
emission effects determined through vehicle testing with the emission
effects predicted by the complex model. Furthermore, each testing
program can be used to identify the effects of only one new fuel
parameter, unless the changes in other fuel parameters are a natural
and inherent consequence of the primary fuel modification. Without this
constraint, EPA believes that accurate determination of the effects of
specific fuel parameters would be more difficult due to the inherent
variability in testing programs and the increased opportunities for
gaming.
In addition, fuel suppliers opting to augment the complex model
through vehicle testing must examine the extent to which emissions are
affected when fuels certified with the augmented complex model are
mixed with other fuels. The Agency is concerned with two potential
problems when different fuels are combined. First, the emission effects
of a parameter, as determined from vehicle testing, may not behave
linearly as fuels with one level of the parameter are mixed with fuels
with different levels of the same parameter. The degree to which this
process occurs is referred to in this notice as the parameter's
dilution effect. Dilution effects are evident in the complex model
proposed in February 1993 and in the model being promulgated today.
Second, the emission effects of various fuel parameters may be affected
by the level of other fuel parameters. The degree to which this process
occurs is referred to in this notice as an interactive effect. If such
effects are present (as in the complex model proposed in February 1993
and in the complex model being promulgated today), actual emission
performance of the fuel mixture in-use could be worse than emission
performance predicted from the complex model augmented by vehicle
testing results. Therefore, the testing process must be structured so
as to identify dilution and interactive effects.
D. Advance Approval of Test Programs
Given the number of factors involved in designing a test program,
the potential for inappropriate design is high. EPA wishes to avoid
submittal of petitions based on test data from poorly designed programs
in order to assure that the time and money invested in such programs is
well-spent and to assure that all augmentations to the model are based
on accurate data from well-designed test programs. Hence EPA will
require petitioners to obtain advance approval from the Agency for
their proposed vehicle testing programs. EPA will consider petitions to
augment the model only if based on the results of approved testing
programs. Furthermore, EPA retains the discretion to evaluate other
data when evaluating petitions to augment the complex model and when
determining the nature, extent, and limitations of the augmentation.
This data may include the existing complex model database, additional
vehicle testing programs, and other augmentation applications.
Petitioners are required to include the following information when
submitting a test program plan for approval: the fuel parameter to be
evaluated for emission effects; the number and description of vehicles
to be used in the test, including model year, model name, VIN number,
mileage, emission performance, technology type, and vehicle
manufacturer; the methods used to procure and prepare the vehicles for
testing; the fuels to be used in the testing program, characterized as
defined in Section V.I.5; the pollutants and emission categories to be
evaluated; the methods and precautions to be used to ensure that the
effects of the parameter in question are independent of the effects of
other parameters already included in the complex model; a description
of the quality assurance procedures to be used during the test program,
and the identity and location of the organization performing the
testing. EPA anticipates and encourages petitioners to submit the
information listed above in stages beginning with the most general and
ending with the most specific in order to streamline the approval
process and eliminate wasted effort. EPA will work with petitioners to
remedy unsatisfactory aspects of their proposed testing program.
These provisions provide the Agency with greater assurance that
petitioners would not selectively report test results to the Agency
that support their petitions. Petitioners would still be able to
``game'' the testing process by pre-screening vehicles to obtain a test
fleet with the desired sensitivity to the proposed parameter. However,
such a test fleet would have to be re-tested as part of the formal test
program and hence would be subject to the variability inherent in
vehicle testing, which would tend to reduce the gaming benefits from
pre-screening. EPA believes that the risks and costs associated with
re-testing will tend to dissuade petitioners from attempting to
manipulate the testing process in this manner.
EPA further requires that the results of all approved testing
programs be submitted to the Agency, even if the parameter in question
proves not to provide an emission benefit. The Agency believes this
requirement is necessary to ensure that all available data is at the
Agency's disposal when evaluating proposed augmentations to the complex
model and when updating the model itself. EPA does not intend to use
this provision to limit legitimate, innovative test programs. Rather,
EPA is only interested in preventing the creation of artificial fuel
parameters that claim to be the source of emission effects which are in
reality only normal statistical variability.
An example may help clarify the problems that can arise if testing
is permitted for such artificial parameters. The level of C10+
aromatics (aromatics whose molecules contain ten or more carbon atoms)
influences a fuel's E200, E300, and total aromatics levels. A testing
program to identify the effects of C10+ aromatics may indicate that an
emission effect from such compounds exists when the effect is actually
due to differences in the fuels' E200, E300, and total aromatics levels
or to the inherent statistical variability associated with vehicle
testing. A petition for approval of a test program to identify the
effects of C10+ aromatics would be required to identify specific
measures to be taken to isolate the emission effects of C10+ aromatics
from those of E200, E300 and total aromatics, all three of which are
included in the complex model. In this example, EPA might require that
certain test fuels contain identical levels of E200, E300, and total
aromatics; that more rigorous statistical tests be used to identify
genuine C10+ aromatics effects beyond those already incorporated in the
complex model for E200, E300, and total aromatics; that the fuels used
in the test program meet more detailed compositional criteria to ensure
their representativeness; or that additional vehicles and/or fuels be
tested. This provision helps assure that the effects observed in
vehicle testing programs are genuine and will occur in-use.
E. Exclusive Rights to Augmentation
EPA's April 1992 and February 1993 proposals discussed the
advantages and disadvantages of providing a system of exclusive rights
to model augmentations. EPA has given this matter further
consideration, including consideration of comments regarding exclusive
rights. The Agency has concluded that the reasons given in its April
1992 proposal for not providing a system of exclusive rights are still
valid. Hence the regulations governing augmentation of the complex
model through vehicle regulation being promulgated today do not provide
for exclusive rights to augmentations. Each augmentation will be
available to any refiner desiring to utilize it, and no restrictions
are provided under this rulemaking for exclusive rights, other than
those granted under other legal code (e.g., patent law). The Agency
does not believe adequate authority exists to promulgate exclusive
rights provisions under this rulemaking. Furthermore, as discussed in
the April 16, 1992 proposal, there are a number of reasons from
economic, administrative, and air quality perspectives that make open
use of model augmentations a desirable public policy.
To allow interested parties to review and comment on a model
augmentation, EPA will publish a description of the augmentation and
its supporting data and information for public comment prior to
approving an augmentation for use. In keeping with the provision of the
Act, EPA will take into account any comments received, and act upon any
request received for fuel certification through model augmentation
within 180 days of such a request being completed.
F. Duration of Augmentation
In its April 1992 proposal, EPA proposed that augmentations would
remain in effect until the next subsequent complex model update was
issued. EPA further proposed that if an augmentation had been valid for
three or fewer years upon implementation of the subsequent update to
the complex model, then refiners were permitted to continue using the
augmentation in conjunction with the previous complex model for an
additional length of time, subject to certain restrictions. EPA has
received a number of comments on this proposal. Today's rule includes a
set of limitations on the duration of the augmentation that incorporate
some elements of these comments. These limitations are described below.
The Agency is concerned that fuel suppliers not be allowed to claim
emission effects in perpetuity based on the testing program described
in this section due to the smaller degree of statistical confidence in
such effects compared to those included in an updated complex model.
The Agency also recognizes the need for fuel suppliers to recoup
investments made to reformulate gasoline, including investments to
utilize the emission effects identified through vehicle testing.
Therefore, petitioners will be permitted to use emission effects
determined through vehicle testing only for a limited period of time.
In general, this period of time extends until an updated version of the
complex model takes effect. Updates to the complex model will be issued
by EPA through a formal rulemaking process at such time that the Agency
determines that sufficient additional data has become available to
warrant issuing such an update. Since some augmentations may be in
place for a relatively short period of time before the model is
updated, the Agency may not be able to adequately assess the
augmentation. However, if a proposed update to the complex model is
issued within three years of the time at which the augmentation takes
effect, then fuel suppliers may be permitted to continue using the
augmentation to determine the emission effects of reformulated
gasolines. Specifically, if the Agency does not formally accept,
reject, or modify the augmentation in question for inclusion in the
updated complex model, then the augmentation will remain available
until the next update to the model takes effect. If the Agency reviews
the augmentation and either excludes the augmentation entirely or
includes the augmentation in a modified form, then the augmentation
will remain available for use in its original form, in conjunction with
the complex model for which the augmentation was issued, to those fuel
producers who can demonstrate to the Administrator's satisfaction that
they have begun producing fuels that are certified using the
augmentation. In such cases, the augmentation may continue to be used
for five years from the date the augmentation took effect or for three
years of fuel production, whichever is shorter.
For the reasons discussed above, augmentations to the model for the
effects of a given parameter over a particular range are permitted only
once. Regardless of whether the emission effects of a parameter are
included in an updated model, the augmentation can neither be used nor
renewed (even with data from a second identical test program) once the
maximum time period for use of a model augmented with the effects of
that parameter has expired. Further testing is permitted, however, to
provide EPA with the additional data needed to include the effect in a
future update to the model.
G. Limits on the Range of an Augmentation
Fuel suppliers will be permitted to claim the emission effects of
augmentations only to the extent that the test program measured the
effects of the fuel parameter in question over the range in question.
If the parameter is included in the complex model, then the
augmentation will be valid for fuels containing levels of the parameter
between the level tested in the test program and the nearest limit of
the complex model (as described in Section IV). If the parameter is not
included in the complex model, then the augmentation will be valid for
fuels containing levels of the parameter between the candidate and
baseline levels (i.e., the levels found in Addition Fuels 1 and 3 in
Table V.1). This provision is intended to be consistent with the limits
on the application of the simple and complex models as expressed in
Sections III and IV.
H. EPA Approval, Confirmatory Testing, and Fees
In the process of reviewing a model augmentation, EPA must confirm
the accuracy of the test results. To this end, EPA intends to monitor
the petitioner's test program. The Agency also reserves the right to
perform confirmatory testing to assure the validity of the test results
and the emission performance of the reformulated fuel before allowing
augmentation of the model. EPA further reserves the right to collect
fees any lawful of an amount sufficient to recoup all costs associated
with such confirmatory testing. EPA anticipates that if any
confirmatory testing is performed that it will be of a limited nature
and focused only on those aspects of the test program which are
unexpected or contrary to prior test programs and engineering
knowledge. Since EPA has not proposed methods to be used to calculate
and collect such fees, these provisions will be handled through a
subsequent rulemaking.
I. Test Requirements
1. Winter Testing
To be certified as reformulated, a gasoline must meet the air
toxics and NOX emission requirements year-round; the oxygen,
benzene, and heavy metal content requirements year-round, and the VOC
emission requirements in the high ozone season. As discussed in Section
IV of this notice and Sections III and IV of the RIA, the Agency does
not have sufficient data to model winter exhaust emissions. While
differences between the effects of fuel parameters under summer and
winter conditions beyond those discussed in Section IV may exist, the
Agency does not have any evidence to date to suggest that they are
significant. Therefore, EPA will apply the exhaust models developed for
summer emissions to winter fuels as well for purposes of determining
their air toxics and NOX emissions. The Agency is concerned that
allowing winter testing for some fuel parameters while modeling the
effects of other parameters based on summer emission data creates the
possibility of ``gaming'' the testing process. Fuel suppliers could use
the summer model to determine the effects of parameters that would
behave unfavorably under winter conditions and use winter testing to
determine the effects of parameters that would behave favorably under
winter conditions. This possibility may result in fuels being certified
for winter use (through a combination of winter testing and summer
modeling) that result in smaller emission reductions in-use than are
intended by the Act or than would occur by using the summer model.
Therefore, EPA is at this time requiring that all testing be performed
under summer ambient conditions. As the Agency gathers additional data
in the future with which to revise the model, EPA will consider whether
sufficient winter test data exists to permit the development of winter
NOX and air toxics models. If such models can be developed, the
Agency will consider whether to allow winter testing.
2. Pollutants to be Measured
To the extent testing is performed to augment the complex model, it
must be performed to determine the emission effects on all the
pollutants covered by the reformulated gasoline certification
requirements, including toxics (carbon monoxide and carbon dioxide
emissions must also be measured to permit validation of test results).
Failure to have such a requirement might result in important emission
effects being overlooked and could allow fuel producers to ``game'' the
certification requirements by permitting them to utilize the modeling
option for one pollutant and the test results for another pollutant
when it would be advantageous. The resulting certified reformulated
gasolines may not meet all of the applicable emission reduction
requirements in-use. For example, the model augmented by test results
may indicate that a fuel meets the VOC requirement but fails the toxics
requirement, while the model alone may indicate that the fuel meets the
toxics requirement but fails the VOC requirement. Allowing the
petitioner to claim the toxics emission effects predicted by the model
while claiming VOC benefits determined through testing would ignore
fuel effects on toxics that may not be addressed by the model.
Testing costs would be significantly reduced if only VOC and
NOX emissions were measured by testing, and toxics emissions were
allowed to be modeled. However, since the testing option can only be
used when the candidate fuel's parameters fall outside of the range of
the model, EPA believes that adequate information seldom would be
available to allow toxics emissions from such fuels to be modeled
adequately if adequate information on VOC and NOX emissions were
not available. If a fuel parameter is expected to affect VOC or
NOX and is not covered by the model, toxics emissions may very
well be affected and should be measured.
It should be noted, however, measurement of toxics emissions for
the fuels used to determine interactive effects (discussed below in
section IV.I.4.) need not be performed. During development of the
complex model, EPA found that interactive effects for air toxics are
either statistically insignificant, impossible to discern given the
accuracy and extent of available data, or too small to contribute
substantially to the model's explanatory and predictive power. The
complex model being promulgated today contains no interactive terms for
air toxics emissions for these reasons, and hence EPA considers it
unnecessary to require testing for interactive effects on air toxics.
Specifically, toxics emissions need not be measured when testing
additional Extension Fuels to determine interactive effects or when
testing Addition Fuels 4, 5, 6, and 7, as described in Section V.I.5.
However, EPA reserves the right to require that toxics be measured
during vehicle testing programs when evidence exists that adverse
interactive effects may exist for toxics. In particular, EPA reserves
the right to require testing for interactive toxics effects if future
revisions to the complex model include such effects.
To better optimize the test program for the particular fuel
parameter being evaluated, the Administrator may approve a request to
waive certain pollutant measurement requirements contained in this
section. Any such waiver would have to be obtained in advance of
vehicle testing. A request for such a waiver must include an adequate
justification for the requested change, including the rationale for the
request and supporting data and information. Such a request must
justify the reason that measurement of certain pollutants clearly is
not necessary, and identify those pollutants for which additional
testing may be warranted. For example, a petition might note that
reducing the concentration of a specific high molecular weight aromatic
decreased VOC emissions even though the overall concentration of
similar aromatics remained unchanged. The petitioner may be able to
justify a reduced need for toxics measurement based on the results of
other studies which show that toxics are proportional to total
aromatics rather than to individual aromatics species. In exchange,
additional testing may be justified for VOC emissions to enable a
greater degree of statistical confidence in the test results. As a
result, the fuel supplier may be able to present EPA with sufficient
justification to warrant increased testing for VOC emissions and
decreased testing for toxics emissions.
3. Exhaust and Nonexhaust Testing
VOC and air toxics emissions occur in both exhaust and nonexhaust
emissions. However, EPA believes that the relationship between fuel
characteristics and nonexhaust emissions is known with greater
certainty and precision than the relationship between fuel
characteristics and exhaust emissions. Nonexhaust emissions are a much
simpler phenomenon to model than exhaust emissions. Nonexhaust
emissions are driven primarily by well-understood principles of
physical chemistry and are modified by devices such as charcoal
canisters that are relatively easily modeled. Exhaust emissions, by
contrast, involve combustion and catalysis reactions that are not as
well understood theoretically and are much more difficult to model. In
addition, exhaust emissions are estimated directly from the Federal
Test Procedure (FTP) utilizing the Urban Dynamometer Driving Schedule,
while nonexhaust emissions are estimated from both FTP and non-FTP test
cycles in a complex process. Finally, data on nonexhaust emissions is
much more extensive and internally consistent than data for exhaust
emissions. For these reasons, EPA is restricting testing to augment the
model to exhaust emission testing. Vehicle testing of nonexhaust
emissions will not be accepted by EPA as the basis for augmentations to
the nonexhaust emission model promulgated in today's rulemaking.
EPA reserves the right to revise the nonexhaust emission model in
the future to reflect new data acquired by the Agency, with such
revisions taking effect after the start of Phase II of the program. In
particular, either a new MOBILE model or ongoing research aimed at
modeling nonexhaust emissions as a function of true vapor pressure over
a range of temperatures may provide the basis for a revised nonexhaust
model. The nonexhaust complex model being promulgated today relies on
the Reid vapor pressure (RVP) to characterize fuels' nonexhaust
emission characteristics. However, RVP is measured at a fixed fuel
temperature (100 deg.F), while nonexhaust emissions occur over a wide
range of fuel temperatures (80 deg.F to 130 deg.F). Since different
oxygenates alter the relationship between RVP and true vapor pressure
at a given temperature to different extents, EPA believes that a model
based on true vapor pressure would be more accurate for fuels
containing oxygenates than a model based solely on RVP.
By permitting nonexhaust emissions from a given fuel to be
estimated only from models and exhaust emissions to be estimated based
in part on vehicle testing, EPA believes that the accuracy of fuel
emission estimates will be enhanced. EPA also believes that this
restriction will focus testing resources on those emission effects
which the model predicts with the least degree of certainty (i.e.,
exhaust emissions), thereby improving the degree of certainty of
emission predictions over the long run.
4. Eligibility of Fuel Properties for Testing
In providing for augmentation of the complex model through vehicle
testing, EPA's intent is to provide refiners with the ability to take
advantage of new or ongoing research into the relationship between fuel
properties and exhaust emissions. As discussed elsewhere in this
section, however, the Agency believes that the complex model is more
accurate and reliable than any single test program for the parameters
included in the model.
Therefore, augmentation by testing will be permitted only for
certain fuel parameters and for certain levels of those parameters.
Augmentations will not be permitted for fuel parameters that are
included and quantified in the complex model database, regardless of
whether they appear in the complex model itself. Such parameters were
either not identified or identified and later rejected during the
rulemaking process, which included a series of regulatory negotiation
meetings, public workshops, and public meetings. EPA believes that the
opportunities for error far exceed the potential emission benefits from
allowing model augmentations using parameters that did not survive the
peer review process.
Augmentation through vehicle testing will be permitted to extend
the valid range of the complex model for parameters already included in
the model. The purpose of such testing would be to determine the
behavior of the parameter within this extended range. Augmentations
also will be permitted for parameters that neither have been included
in today's complex model nor were measured for the fuels contained in
the complex model database. The purpose of testing in this case would
be to determine the behavior of new parameters, including any dilution
and interactive effects. The test requirements differ for these two
cases to reflect differences in existing knowledge and environmental
risk.
5. Test Fuels
The Agency has three major goals that must be satisfied before
accepting an augmentation to the complex model. First, the augmentation
must provide proper credit for fuel modifications. Second, the
augmentation must account for dilution effects properly. Third, the
augmentation must account for interactive effects between the parameter
being tested and other fuel parameters properly. EPA believes that
these three goals cannot be met without specifying at least some of the
characteristics of fuels to be included in a test program. The
remainder of this section describes the basic characteristics of the
fuels required as part of a vehicle test program.
a. Fuels required to extend the range of existing complex model
parameters. Three ``extension fuels'' must be included in test programs
intended to extend the range of the complex model for a given parameter
to a more extreme level. Extension fuel #1 would contain the more
extreme level of the parameter being extended in order to determine the
parameter's effects on emissions at this more extreme level. Extension
fuel #2 would contain the parameter being extended at levels at or near
its current lower limit in the model. Extension fuel #3 would contain
the parameter being extended at levels at or near its current upper
limit in the model. These latter two fuels are necessary in order to
estimate the size and significance of squared terms involving the
parameter being extended. For all three fuels, the levels of other
complex model parameters are to be set at the levels specified in Table
V.2, which the Agency believes are representative of levels that will
be found in typical reformulated fuels. In addition, all three fuels
must be blended from representative refinery streams to the extent
practicable. The three extension fuels must meet the requirements
presented in Tables V.1 and V.2 to within the blending tolerances
specified in Table V.4.
If the Complex Model contains interactive effects between the
parameter in question and other parameters, two additional fuels must
be tested to quantify the magnitude of any such effect at extended
levels of the parameter in question. For each interacting parameter,
the two additional fuels would contain the parameter being tested at
levels identical to that found in Extension Fuel #1. The interacting
parameter would be present at the levels specified in Table V.1 for
Extension Fuels 2 and 3, respectively, in the two additional fuels in
order to quantify the size of the interactive effect over its full
range. Other parameters would be set at the levels specified in Table
V.2. It should be noted that since today's complex model includes only
one interactive term (involving aromatics and E300), this situation
would arise relatively infrequently.
Table V.1.--Level of Existing Complex Model Parameters Being Extended
------------------------------------------------------------------------
Extension Extension Extension
Fuel property being extended fuel # fuel #2 fuel #3
------------------------------------------------------------------------
Sulfur, ppm........................ Extension 80 450
Level.
Benzene, vol%...................... Extension 0.5 1.5
Level.
RVP, psi........................... Extension 6.7 8.0
Level.
E200, %............................ Extension 38 61
Level.
E300, %............................ Extension 78 92
Level.
Aromatics, vol%.................... Extension 20 45
Level.
Olefins, vol%...................... Extension 3.0 18
Level.
Oxygen, wt%........................ Extension 1.7 2.7
Level.
Octane, R+M/2...................... 87.5......... 87.5 87.5
------------------------------------------------------------------------
Table V.2.--Levels for Fuel Parameters Other Than Those Being Extended
------------------------------------------------------------------------
Extension Extension Extension
Fuel property fuel #1 fuel #2 fuel #3
------------------------------------------------------------------------
Sulfur, ppm............................ 150 150 150
Benzene, vol%.......................... 1.0 1.0 1.0
RVP, psi............................... 7.5 7.5 7.5
E200, %................................ 50 50 50
E300, %................................ 85 85 85
Aromatics, vol%........................ 25 25 25
Olefins, vol%.......................... 9.0 9.0 9.0
Oxygen, wt%............................ 2.0 2.0 2.0
Octane, R+M/2.......................... 87.5 87.5 87.5
------------------------------------------------------------------------
b. Fuels required to qualify new complex model fuel parameters.
Seven ``addition fuels'' must be included in test programs intended to
augment the complex model with fuel parameters not included in the
model. These fuels are intended to provide the data necessary to
estimate linear, squared, and interactive emission effects for the
parameter being tested. The fuel parameter values for all seven
addition fuels are specified in Table V.3; these values must be met to
within the blending tolerance ranges specified in Table V.4.
Table V.3.--Properties of Fuels To Be Tested When Augmenting The Model With A New Fuel Parameter
----------------------------------------------------------------------------------------------------------------
Fuels
Fuel property ---------------------------------------------------------------------
1 2 3 4 5 6 7
----------------------------------------------------------------------------------------------------------------
Sulfur, ppm............................... 150 150 150 35 35 500 500
Benzene, vol%............................. 1.0 1.0 1.0 0.5 0.5 1.3 1.3
RVP, psi.................................. 7.5 7.5 7.5 6.5 6.5 8.1 8.1
E200, %................................... 50 50 50 62 62 37 37
E300, %................................... 85 85 85 92 92 79 79
Aromatics, vol%........................... 27 27 27 20 20 45 45
Olefins, vol%............................. 9.0 9.0 9.0 2.0 2.0 18 18
Oxygen, wt%............................... 2.1 2.1 2.1 2.7 2.7 1.5 1.5
Octane, (R+M)/2........................... 87 87 87 87 87 87 87
New Parameter\1\.......................... C C+B B C B C B
----------
2
----------------------------------------------------------------------------------------------------------------
\1\C=Candidate level, B=Baseline level.
In Table V.3, Fuel 1 is the candidate fuel, Fuel 3 is the
candidate-baseline fuel, and Fuel 2 is a dilution fuel that is tested
to determine whether emissions respond linearly to levels of the
candidate fuel parameter. Testing on addition fuels 1, 2, and 3 will
provide the data needed to assess the emission effects of the parameter
being tested in isolation. Three separate levels of the parameter are
specified in order to provide data to estimate both linear and squared
terms involving the parameter, while other fuel parameters have been
set at levels expected to be typical of in-use reformulated gasolines.
Fuels 4 and 5 are low-emitting fuels with candidate and baseline levels
of the parameter in question. Fuels 6 and 7 are the corresponding high-
emitting fuels. Testing on these four fuels will provide the data
needed to assess the existence and size of interactive effects between
the parameter being tested and other fuel parameters already included
in the complex model. Estimating these effects for very high emitting
fuels (addition fuels 6 and 7) and very low emitting fuels (addition
fuels 4 and 5) maximizes the sensitivity of the test program to such
effects.
If the parameter being tested is not specified for CAA baseline
gasoline, its baseline level must be comparable to its level in
gasoline representative of commercial reformulated gasolines.
Petitioners are required to obtain approval for the baseline level of
this parameter from the Agency prior to beginning their vehicle test
programs. Such approval would depend in part on the use of an
appropriate basis for determining the properties of ``representative''
commercial reformulated gasolines. The basis for this specification and
for the specifications described in Table V.3 are discussed more fully
in section IV.G of the RIA.
c. Other fuels requirements. To produce fuels with the parameter
values listed above for the extension and addition fuels, the amount
and type of paraffins present in each fuel may require adjustments.
These adjustments must reflect the distribution of paraffin types in
representative refinery streams. Two other issues must also be
addressed regarding the composition and properties of extension and
addition fuels. First, non-compositional fuel properties such as RVP,
E200, and E300 may differ from the values specified in Tables V.2 and
V.3 as a natural result of compositional differences among fuels or as
a result of the inherent variability in blending processes. In such
cases, the complex model is to be used to compensate for such
differences when evaluating vehicle testing results, as described in
section 80.48 of today's regulations.
Second, EPA also is concerned that variations due to blending may
cause fuel parameters not included in the model to vary among fuels,
and such parameters may have significant emission effects not predicted
by the model. To minimize this risk, the properties of the various
fuels must match those specified in Tables V.1 through V.3 to within
the tolerances defined in Table V.4. In addition, the extension and
addition fuels must be blended from identical refinery streams to the
extent possible. Failure to meet this requirement would reduce the
certainty that emission effects found in vehicle testing are due solely
to the parameter being tested. However, if a petitioner can show that
it is not feasible to meet all such tolerances for the petitioner's
fuels due either to: (1) Naturally-resulting changes in fuel parameters
arising from changes in the parameter(s) in question or (2) blending
technology limitations, EPA will consider modifying the relevant
tolerances. Any such request must come prior to the start of the test
program. In such cases, EPA reserves the right to use the model and
relevant data from prior augmentation petitions to adjust for whatever
differences remain among the fuels.
Table V.4.--Fuel Parameter Blending Tolerances
------------------------------------------------------------------------
Blending
Fuel parameter tolerance
------------------------------------------------------------------------
Sulfur content....................................... 25
ppm.
Benzene content...................................... 0.2
vol %.
RVP.................................................. 0.2
psi.
E200 level........................................... 2 %.
E300 level........................................... 4 %.
Oxygenate content.................................... 1.0
vol %.
Aromatics content.................................... 2.7
vol %.
Olefins content...................................... 2.5
vol %.
Saturates content.................................... 2.0
vol %.
Octane............................................... 0.5.
Candidate parameter.................................. To be determined
as part of the
augmentation
process.
------------------------------------------------------------------------
An octane requirement of 87.5 (measured by the (R+M)/2 method) must
be met for all fuels used in vehicle testing to within the tolerance
specified in Table V.4, unless octane itself is the fuel property being
evaluated for its effect on emissions. All test fuels must also contain
detergent additives in concentrations adequate to meet the requirements
of section 211(l) of the Act, and the concentration must be within ten
percent of the average detergent concentration for all fuels included
in the test program.
6. Test Procedures
For the reformulated gasoline program to achieve actual in-use
reductions in fuel-related VOC and toxics emissions, certification test
results must correlate with reductions in in-use emissions. No test
procedure, however, is completely representative of all in-use
conditions. The range of vehicle uses and operating conditions and the
range of geographical and climatic conditions throughout the country
prevent a single test procedure from being entirely representative.
However, EPA has developed or is in the process of developing test
procedures which attempt to reflect a broad spectrum of in-use vehicle
operating conditions. These test procedures were used in part to
develop the emission factors in EPA's MOBILE4.1, MOBILE5, and MOBILE5A
emission models, which in turn have been used to develop the modeling
option for fuel certification. To maintain consistency between the
certification methods, these test procedures also are to be used for
vehicle testing to augment the model.
a. Exhaust emission testing. Exhaust emissions must be measured
through the use of the Federal Test Procedure (FTP) for new vehicle
certification (Subpart B of Part 86 of the Code of Federal Regulations)
with modifications to allow vehicle preconditioning between tests on
different fuels and to provide for benzene, formaldehyde, acetaldehyde,
and 1,3-butadiene sampling and analysis. Since POM (the fifth regulated
toxic air pollutant) cannot currently be measured accurately and since
no single measurement procedure is generally accepted, its measurement
is not required. A detailed description of the toxics measurement
procedures can be found in section 80.55 and section 80.56 of the
regulations for this rulemaking.
b. Fuel parameter measurement precision. One source of error in
testing programs as described in this section is uncertainty in the
composition and properties of the fuels being tested. Since fuel
testing is far less expensive than vehicle emission testing, EPA
believes it is highly cost effective to measure the properties of the
fuels multiple times to reduce the uncertainty in projected emissions
due to uncertainty in fuel composition. As a result, at minimum, the
properties defined in Table V.5 must be measured a sufficient number of
times to reduce the 95 percent confidence interval, as calculated using
a standard t-test, to the tolerances defined in Table V.5.
Table V.5.--Fuel Parameter Measurement tolerances for Fuel Certification
by Vehicle Testing
------------------------------------------------------------------------
Measurement
tolerance (95
Parameter percent confidence
interval)
------------------------------------------------------------------------
API Gravity....................................... 0.2
deg.API.
Sulfur content.................................... 5 ppm.
Benzene content................................... 0.05 vol
%.
RVP............................................... 0.08
psi.
Octane............................................ 0.1 (R+M/
2).
E200 level........................................ 2 %.
E300 level........................................ 2 %.
Oxygenate content................................. 0.2 vol
%.
Aromatics content................................. 0.5 vol
%.
Olefins content................................... 0.3 vol
%.
Saturates content................................. 1.0 vol
%.
Octane............................................ 0.2.
Candidate parameter............................... To be determined as
part of the
augmentation
process.
------------------------------------------------------------------------
EPA recognizes that fuels used in vehicle testing may differ
significantly in composition in terms of specific chemical species
while appearing to be identically composed in terms of broad chemical
families. The Agency further recognizes that such compositional
differences may result in emission effects, and that such differences
may confound or be used to ``game'' testing programs. Therefore, the
fuels used in vehicle testing must be blended from representative
refinery streams, and their composition must be fully characterized by
gas chromatography or equivalent analysis methods (following the
methodology used in the Auto/Oil study3) and the results submitted
to EPA. Petitioners would have the option of either submitting these
results for approval prior to beginning vehicle testing or including
these results in their completed petition. However, in either case, EPA
would retain the authority to require modifications to the test fuels
to ensure that their compositions are appropriate. Hence petitioners
electing not to obtain prior approval of their fuel compositions would
assume the risk that EPA may require modifications to the petitioner's
test fuels upon receipt of the completed petition, thereby invalidating
any testing the petitioner may have completed.
---------------------------------------------------------------------------
\3\Auto/Oil Air Quality Improvement Research Program, Technical
Bulletin #1, December 1990.
---------------------------------------------------------------------------
EPA received a number of comments on its fuel specification and
measurement precision proposals. Many of these comments have been
incorporated in today's testing regulations, notably removal of the end
point specification and inclusion of detergents and octane
specifications. A detailed discussion of comments can be found in
Section VI.G of the RIA.
c. Other test fuel provisions. To maximize the accuracy and
confidence in the results from a test program of the magnitude
specified in this section, it is good practice to ensure that
systematic changes in the emission characteristics of the test vehicles
do not occur during testing. Such effects can overwhelm the fuel
effects being measured. Therefore, the first fuel tested in any given
vehicle must be retested in that vehicle at the end of the test
program. In addition, the order in which fuels are tested on each
vehicle must be randomized to prevent carryover effects from biasing
test results.
In response to comments, EPA has decided to remove the requirement
for repeat measurements of VOC and NOX emissions from each fuel.
EPA considers the measures described above to provide adequate quality
assurance without repeat measurements and recognizes that removal of
the repeat testing requirements will make vehicle testing significantly
less onerous and time-consuming.
7. Vehicle Selection
a. 1990 Equivalency. Section 211(k)(3) of the CAA specifies that
the required reductions in VOC and toxics emissions are to be measured
from the emissions of those pollutants from ``baseline vehicles.''
Section 211(k)(10)(A) defines baseline vehicles as representative model
year 1990 (MY-90) vehicles. However, in order to simplify test vehicle
selection and remain consistent with the practices used to develop the
complex model, other model year vehicles may be included in the test
program. Specifically, 1986 through 1989 model year vehicles may be
tested if the 1990 version had an engine and exhaust system that was
not different from the earlier model year versions in ways that could
affect the emission performance of the vehicles (i.e., if the model's
EPA emission certification data were ``carried over'' through the 1990
model year4). EPA retains the right to reject any non-1990 model
year vehicle that the manufacturer deems to be different in terms of
emission control technology or engine design from 1990 vehicles made by
that manufacturer. The test fleet must be composed only of light-duty
vehicles and light-duty trucks, in keeping with the practices followed
in developing the complex model.
---------------------------------------------------------------------------
\4\For a more complete explanation of this issue, please see
``1990 Baseline Vehicles,'' memorandum from David Korotney to EPA
Air Docket A-92-12, November 30, 1993.
---------------------------------------------------------------------------
b. Vehicle selection criteria. Another consideration in vehicle
selection is the condition of the test vehicles. EPA believes that
Congress intended that the required VOC and toxics emission reductions
be achieved not only at certification but also in-use. In order for
this to be true, the test vehicles' condition should be representative
of that of in-use vehicles. Therefore, for the purposes of the
reformulated gasoline program, representative vehicles must have
emission performances typical of the in-use emission performance of
1990 vehicles over their lifetime, a technology mix similar to that of
the 1990 model year fleet, and a minimum of 4,000 miles of service to
assure break-in of engine and emission control system components. In
addition, the test fleet must contain vehicles with a distribution of
VOC emissions similar to that of in-use vehicles. Emissions of other
pollutants tend to respond in a similar manner (e.g., carbon monoxide
and air toxics) or in an essentially uncorrelated manner (e.g.,
NOX).
In order for the emissions effects measured during vehicle testing
to reflect the emission effects that will be experienced by actual in-
use vehicles, EPA considers it necessary to control the composition of
the test fleet. As discussed in Section IV, EPA's complex model has
identified significant differences in the effects of fuel modifications
on emissions among vehicles from different emitter classes and
technology groups. EPA's vehicle fleet requirements are intended to
assure that a sufficient number of vehicles are tested to provide
statistical confidence in observed emission effects, to assure that the
vehicles tested are representative of the emission characteristics of
in-use vehicles, and to assure that the vehicles tested have emission
control technologies that are representative of emission control
technologies found on 1990 model year vehicles.
(1) Higher Emitters/Normal Emitters. In order that the test fleet
for exhaust emission testing reflect the distribution in vehicle
emission performance in-use, the test fleet must consist of two exhaust
VOC emitter subfleets, normal emitters and higher emitters. The
proportion of vehicles in each subfleet is to be set equal to the
distribution of vehicle emission performance when enhanced I/M programs
are in place. These proportions are shown in Table V.6, which is based
on an EPA analysis5 of the distribution of the in-use emission
performance of a hypothetical fleet composed entirely of 1990 model
year vehicles when subject to an enhanced I/M program. This
distribution is consistent with the assumptions made in developing the
Phase II Complex Model.
---------------------------------------------------------------------------
\5\``Exhaust VOC Emission Inventory By Vehicle Emitter Class
Following Implementation of an Enhanced Inspection and Maintenance
(I/M) Program'', Memorandum from Christian Lindhjem and David
Brzezinski to EPA Air Docket A-92-12, June 24, 1993.
Table V.6.--Emitter Groups and In-Use Emissions
------------------------------------------------------------------------
Fraction Emission
of in- fraction
Emitter group use -----------------
fleet VOCs NOX
------------------------------------------------------------------------
Normal: <2 x THC Standard (<0.82 g/mi)...... 0.738 0.444 0.738
Higher: 2 x THC Standard (0.82 g/mi).............................. 0.262 0.556 0.262
------------------------------------------------------------------------
An option had been proposed for comment which would not have
separated the test fleet into separate emitter groups under the
assumption that they may not respond differently to fuels. However,
EPA's analysis of the complex model database and the complex model
itself indicates that this assumption is invalid. Hence EPA has
determined that the test fleet must contain vehicles from both emitter
groups.
Assembling a test fleet with the specified emission performance
distribution requires vehicles to be obtained with the desired emission
performance. For the reformulated gasoline program, such vehicles must
be obtained by randomly selecting vehicles with the desired emission
performance from the in-use fleet and testing those vehicles in their
as-received condition. This method helps assure that the vehicles
selected for testing have emission control problems that are
representative of in-use emission problems. EPA had considered allowing
normal emitting vehicles with intentionally-disabled emission control
systems to serve as higher emitting vehicles, but no suitable
disablement scheme has been identified and evidence indicating that
disabled vehicles would have emission performance representative of in-
use higher emitters has not been found. For these reasons, EPA will not
permit higher emitting vehicles to be created by intentionally
disabling normal emitting vehicles.
Test vehicles' emission performance will need to be pre-screened to
place them in the appropriate emitter group and to assure the proper
emissions distribution within the test fleet. Such prescreening tests
must be conducted using EPA vehicle certification fuel (Indolene) over
the Federal Test Procedure since these were the conditions which were
used to generate the data for the in-use emission distribution.
Prescreening tests can also be performed using the Clean Air Act
baseline gasoline and/or the I/M 240 test procedure. Results from such
tests can be correlated with FTP test results with Indolene (as
outlined in section 80.62 of the accompanying regulations).
(2) Technology Groups. As discussed in Section IV, the development
of the complex model revealed that the emissions effect of fuel
modifications in normal emitting vehicles varied among the engine and
exhaust system technologies present in 1990 model year vehicles. Hence
EPA has concluded that the normal emitter test fleet must have a
technology distribution that is representative of the technology
distribution present in the 1990 model year fleet. The required
distribution is shown in Table V.7.
In addition to the technology group criteria of Table V.7,
approximately 30 percent of the vehicles selected for each emitter
class sub-fleet must be light-duty trucks (LDTs) to reflect the
representation of LDTs in the light-duty vehicle fleet. EPA believes
that the benefits of providing flexibility in determining the selection
of LDTs for the test fleet outweigh the benefits of accuracy achieved
by specifying which vehicles from Table V.7 should be LDTs. However, as
is also the case for other design elements of the test program, the
distribution of LDTs among the normal emitter technology groups is
subject to EPA approval.
A number of commenters objected to the application of this
technology group distribution to the higher emitting vehicle subfleet,
as was specified in prior proposals. EPA's experience in developing the
complex model, as discussed in Section IV and the RIA, confirms that
higher emitter emissions tend to be much less dependent on vehicle
technology differences than are normal emitter emissions. Therefore,
the higher emitting vehicle subfleet need not meet the technology
distribution requirement, though a mixture of vehicle models and
manufacturers should still be included. The higher emitter subfleet
also must meet the 1990 model year and light duty vehicle criteria
described previously and, like other elements of proposed testing
programs, is subject to EPA approval.
Table V.7.--Test Vehicle Characteristics
----------------------------------------------------------------------------------------------------------------
Tech.
Veh. # Fuel system Catalyst Air injection EGR group Manufacturer
----------------------------------------------------------------------------------------------------------------
1.......................... Multi....... 3W No Air........ EGR........... 1 GM.
2.......................... Multi....... 3W No Air........ No EGR........ 2 Ford.
3.......................... TBI......... 3W No Air........ EGR........... 3 GM.
4.......................... Multi....... 3W+OX Air........... EGR........... 4 Ford.
5.......................... Multi....... 3W No Air........ EGR........... 1 Honda.
6.......................... Multi....... 3W No Air........ No EGR........ 2 GM.
7.......................... TBI......... 3W No Air........ EGR........... 3 Chrysler.
8.......................... Multi....... 3W+OX Air........... EGR........... 4 GM.
9.......................... TBI......... 3W+OX Air........... EGR........... 7 Chrysler.
10......................... Multi....... 3W Air........... EGR........... 5 Toyota.
11......................... Multi....... 3W No Air........ EGR........... 1 Ford.
12......................... Multi....... 3W No Air........ No EGR........ 2 Chrysler.
13......................... Carb........ 3W+OX Air........... EGR........... 9 Toyota.
14......................... TBI......... 3W No Air........ EGR........... 3 Ford.
15......................... Multi....... 3W+OX Air........... EGR........... 4 GM.
16......................... Multi....... 3W No Air........ EGR........... 1 Toyota.
17......................... Multi....... 3W No Air........ No EGR........ 2 Mazda.
18......................... TBI......... 3W No Air........ EGR........... 3 GM.
19......................... Multi....... 3W+OX Air........... EGR........... 4 Ford.
20......................... Multi....... 3W No Air........ EGR........... 1 Nissan.
----------------------------------------------------------------------------------------------------------------
Table V.8--Technology Group Definitions
----------------------------------------------------------------------------------------------------------------
Tech. group Fuel system Catalyst Air injection EGR
----------------------------------------------------------------------------------------------------------------
1........................................... Multi......... 3W No Air.......... EGR
2........................................... Multi......... 3W No Air.......... No EGR
3........................................... TBI........... 3W No Air.......... EGR
4........................................... Multi......... 3W+OX Air............. EGR
5........................................... Multi......... 3W Air............. EGR
6........................................... TBI........... 3W Air............. EGR
7........................................... TBI........... 3W+OX Air............. EGR
8........................................... TBI........... 3W No Air.......... No EGR
9........................................... Carb.......... 3W+OX Air............. EGR
----------------------------------------------------------------------------------------------------------------
Legend for Tables V.7 and V.8
Fuel System:
Multi = Multi-point fuel injection
TBI = Throttle body fuel injection
Carb = Carburetted
Catalyst:
3W = 3-Way catalyst
3W+OX = 3-Way catalyst plus an oxidation catalyst
Air Injection:
Air = Air injection
No Air = No air injection
EGR:
EGR = Exhaust gas recirculation
No EGR = No exhaust gas recirculation
Vehicles must be added to the normal emitter sub-fleet in the order
in which they appear in the table. If more than 20 vehicles are
included in the normal emitter sub-fleet, then the additional vehicles
must be selected starting over with vehicle number one in Table V.7.
(3) Number of Test Vehicles. Exhaust emissions are subject to
considerable variability due to the complexity of combustion chemistry,
engine behavior, and emission control. As a result, substantial
statistical uncertainty typically exists in exhaust emission reduction
estimates based on a single test program. To reduce this uncertainty,
an adequate number of vehicles must be tested for their exhaust
emissions. In order to keep statistical uncertainty reasonably low
while at the same time limit the test fleet size to reasonable levels,
the test fleet for exhaust emissions must consist of a minimum of 20
vehicles. To maintain adequate statistical confidence in test results,
however, the distribution of the test fleet among the emitter groups
must also be defined so as to minimize statistical uncertainty. As
discussed in the April 16, 1992 proposal, differences in VOC, NOX
and toxics emission distributions for in-use vehicles prevents
optimization of the size of the emitter groups for all three pollutants
simultaneously. EPA is basing the number of vehicles in each emitter
group on their VOC emission performance, based on the reasons discussed
in the April 16, 1992 proposal and on the use of VOC emission
performance to define emitter groups.
The uncertainty associated with VOC emissions is quite complex. The
higher emitting vehicles in various test programs have tended to have
significantly greater variability in emission effects than normal
emitting vehicles. Hence to minimize statistical uncertainty, a greater
proportion of higher emitters should be tested than would be suggested
by their contribution to in-use emissions. However, EPA believes that
pre-screening and stabilization of higher emitters can reduce their
variability to approach that of normal emitters. Therefore, to minimize
the statistical uncertainty in the test program the number of normal
and higher emitters in the test fleet should represent the contribution
of each sub-fleet to total in-use emissions. Since the relative
contribution of normal and higher emitters to total VOC emissions is
approximately equal (as discussed at length in the RIA), equal numbers
of normal and higher emitters must be contained in any test fleet.
(4) Waiver Provisions for Different Test Program Requirements. A
number of options were discussed in April 16, 1992 which attempted to
simplify or minimize the vehicle test fleet requirements while still
maintaining the statistical confidence in the results of any test
program. Based upon EPA's experience with the programs conducted as
part of the complex model development, the test fleet provisions
promulgated here represent the minimum possible if adequate statistical
confidence in test program results is to be maintained. In fact, EPA
believes that many petitioners may desire to test additional vehicles
in order to improve their study's statistical power and thereby improve
the likelihood that an augmentation petition would be granted.
Nevertheless, in some instances petitioners may believe that a more
optimal test fleet composition than the one specified above exists for
the fuel parameter being tested. In such cases, petitioners can
petition the Administrator to approve a waiver from certain of the
requirements in this section relating to the number of test vehicles
and their distribution among the normal and higher emitter groups. Any
such waiver would have to be obtained in advance of the start of the
test program involved. A request for such a waiver must include an
adequate justification for the requested change, including the
rationale for the request and supporting data and information. EPA
reserves the right to require testing of additional vehicles beyond the
20-vehicle minimum where such testing is necessary to evaluate emission
effects properly.
8. Data Analysis
a. Weighting of emission test data. The manner in which the test
data is to be analyzed must be consistent with the goal that the
emission benefits from reformulated gasoline be realized in-use, just
as is the case for the exhaust emission complex model itself (as
discussed in Section IV). Therefore, augmentation of the models with
vehicle testing results must reflect the effects of fuel modifications
on emissions of each exhaust pollutant (VOC, NOX, benzene, 1,3-
butadiene, formaldehyde, and acetaldehyde) on 1990 vehicles. The
augmentation also must incorporate differences in these effects for
vehicles with different emission control technologies and different
emission levels. The vehicle selection criteria discussed above are
intended to satisfy these requirements without requiring an extremely
large test fleet. The results of vehicle test programs will be weighted
to reflect the contribution of each emitter class and technology type
to in-use emissions according to the procedure described in Section IV
for the exhaust emission complex model.
b. Data analysis to extend the range of existing model parameters.
When extending the range of a fuel parameter already included in the
complex model, EPA believes that the data generated through vehicle
testing should be combined with the data used to develop the complex
model itself. This approach offers several important advantages. First,
it takes full advantage of existing knowledge regarding the effects of
the parameter in question on emissions. Second, it reduces
inconsistencies between the complex model and the augmentation, thereby
simplifying certification and enforcement. Third, it reduces the
possibility of petitioners deliberately manipulating the test program
to obtain a desired augmentation since the limited data generated by
the test program will be combined with the much more extensive data
available in the complex model database.
The analysis process is described in detail in section 80.48 of
today's regulations and in Section IV.G of the RIA. The process
requires that the emission effects of the parameter being tested be
verified at the extended level while not permitting emission effects of
other parameters to be modified from the effects incorporated in the
complex model. In addition, the augmentation would only apply to fuels
with levels of the parameter being tested that fall outside the range
for which the complex model is valid. These safeguards are intended to
prevent the results of vehicle testing from being used to alter aspects
of the complex model that a fuel supplier or other organization deems
undesirable.
c. Data analysis to add new fuel parameters. Vehicle test data for
new fuel parameters such as new additives cannot be analyzed in the
manner described above for existing fuel parameters. Vehicle-to-vehicle
variability can cause significant differences in vehicle responses to
parameters already included in the complex model from what the complex
model would predict. The analysis method described above would apply
these differences entirely to the new parameter, which would allow
substantial opportunities to game the testing and model augmentation
process. To minimize the risk of gaming and assure proper
representation of the effects of new fuel parameters, a different
analysis process must be used when augmenting the model with a new fuel
parameter. This process is designed to identify the effects of the new
parameter itself, including its behavior upon dilution, as well as any
interactive effects between the parameter and existing complex model
parameters.
The process itself is described in detail in section 80.48 in
today's regulations and in Section IV of the RIA. The modeling process
incorporates five techniques to minimize gaming and isolate the actual
emission effects of the new parameter being tested. First, the complex
model is used to adjust the emissions performance of the test vehicles
on the three fuels for any differences in fuel parameters other than
the one being tested. These adjustments should be minor, since fuel
properties other than the one being tested are required to be nearly
identical. Second, the linear and squared terms for the new parameter
are determined based on test data from addition fuels 1, 2, and 3
before interactive effects are introduced into the augmented complex
model based on the results of testing addition fuels 4, 5, 6, and 7.
This approach is used because the direct effects of fuel parameters
(represented by the linear and squared terms) are less easily gamed or
obscured than are interactive effects since fewer variables are
involved. Third, the statistical criteria defined in section 80.57 are
used to assure that only statistically significant terms are included
in the augmentation.
Fourth, the model must include all terms for the pollutant being
modeled that are already included in the complex model. In addition,
only the linear, squared, and interactive terms involving the new
parameter are permitted to enter the augmentation. The coefficients for
the complex model terms will be fixed at the values established in this
rule. By not permitting the augmentation to change existing complex
model terms, the analysis process reduces opportunities to game to
modify complex model effects that the testing organization considers
undesirable.
Fifth, augmentations are not permitted for parameters not contained
in the complex model but for which measurements exist in the complex
model database. Including such parameters in an augmented complex model
is likely to result in large changes in complex model coefficients due
to the interrelationship between fuel properties. Such changes would
complicate enforcement and might introduce fungibility problems that
would diminish the in-use effectiveness of reformulated fuels. Further,
EPA's experience in developing the complex model suggests that
including such parameters would introduce collinearity problems and
exacerbate the risk of test program gaming. Since such parameters were
considered for inclusion in the complex model but were rejected based
on input from affected parties and EPA staff, EPA has decided not to
permit augmentations for such parameters. However, the Agency will
consider including such parameters in subsequent revisions to the
complex model.
Interactive terms were not permitted to enter EPA's complex models
for exhaust toxics, as discussed in Section IV and the RIA. Hence
interactive effects on toxics emissions are not permitted in
augmentation petitions, unless the test program was intended and
specificially designed to investigate such effects.
The preceding discussion assumes that the interactive effects
identified through testing cannot be traced to a specific cause. If the
cause of the interactive effect can be identified, it may be
appropriate to determine a greater beneficial augmentation due to the
parameter in question than the effects identified through the procedure
above or to include an interactive term in the complex model.
Therefore, EPA will allow testing of additional fuels to identify the
cause of the interactive effect and the magnitude of the effect for
representative in-use fuels (again subject to Agency approval regarding
the appropriateness of the petitioner's definition of representative
gasoline). Petitioners will be required to obtain approval from the
Administrator for the proposed additional testing before beginning such
testing. Petitioners will be permitted to claim larger benefits for the
parameter in question based on the results of such tests, subject to
the approval of the Administrator.
For a more complete description of these procedures, the reader is
referred to section 80.57 of the regulations and to Section IV of the
RIA.
d. Acceptance criteria. As discussed in Section H, EPA reserves the
right to evaluate the quality of testing data submitted in support of
petitions to augment the models, to reject test data or analyses
submitted to the Agency if such data or analyses are found to be
insufficient, flawed, or otherwise deficient, and to include test data
or analyses from other sources when evaluating the proposed
augmentation to the model.
VI. Phase II (Post-1999) Reformulated Gasoline Performance Standards
and NOX Standards for Reformulated Gasoline
A. Introduction
The Clean Air Act (the Act), as amended in November 1990,
establishes a more stringent minimum level of control of ozone-forming
VOCs and air toxics emissions from reformulated gasoline beginning in
the year 2000 than is required prior to that date. For the first five
years of the reformulated gasoline program (Phase I; January 1, 1995
through December 1999), Congress established a minimum requirement of
15% reduction of ozone forming VOCs and toxic air pollutants [CA
section 211(k)(3)(B)].6 Starting with January 1, 2000 (Phase II),
the 15% minimum required reductions are increased to 25%, with the
provision that EPA may increase or decrease this level based on
technological feasibility, considering cost, but may not decrease it
below 20% [CA section 211(k)(3)(B)]. The restriction on increases in
NOX emissions continues to apply during Phase II of the program.
---------------------------------------------------------------------------
\6\The numerical performance standard of Sec. 211(k)(3)(B) sets
the minimum level of reductions, as it is more stringent than the
reductions achieved by the formula fuel in Sec. 211(k)(3)(A).
---------------------------------------------------------------------------
The regulatory negotiation conducted by EPA for this rulemaking did
not address the Phase II VOC and toxics standards, nor did it address a
reduction in NOX emissions beyond the statutory cap imposed under
section 211(k)(2)(A). After analyzing the costs and benefits of various
controls, along with other relevant factors, EPA proposed a range of
possible Phase II standards for VOC and toxics. Furthermore, based on
EPA's view that NOX reductions were important to achieve
attainment of the ozone NAAQS in many nonattainment areas, EPA also
proposed a NOX reduction performance standard for Phase II
reformulated gasoline relying on EPA's authority under section
211(c)(1)(A). A more detailed discussion of EPA's Phase II proposals
for VOCs, toxics, and NOX is provided in subsection 2 below.
For the reasons described below, EPA has decided to establish per
gallon Phase II VOC performance standards of 25.9% for VOC control
region 2 (northern areas) and 27.5% for VOC control Region 1 (southern
areas).7 EPA is also promulgating a per gallon toxics performance
standard of 20% for all reformulated gasoline. Reformulated gasoline
will also have to meet a 5.5% per gallon reduction in emissions of
NOX. EPA has also established more stringent VOC, toxics, and
NOX performance standards where a refiner or importer complies on
average, as well as minimum per gallon standards, as explained in
section C below.
---------------------------------------------------------------------------
\7\The 27.9% VOC performance standard for VOC control region 1
is measured against the statutory baseline gasoline, which has an
RVP of 8.7 psi. This amounts to a 17.7% VOC reduction when measured
against a baseline gasoline with RVP of 7.8 psi.
---------------------------------------------------------------------------
1. Statutory Requirements
Section 211(k)(1) requires that reformulated gasoline achieve the
greatest reductions possible in volatile organic compounds (VOCs) and
toxics emissions, ``taking into consideration the cost of achieving
such emission reductions, any nonair-quality and other air-quality
related health and environmental impacts and energy requirements.
Specifically, section 211(k)(3)(B) of the Act requires that, in the
year 2000 and beyond, ``aggregate emissions of ozone-forming volatile
organic compounds from baseline vehicles8 when using reformulated
gasoline shall be 25 percent below the aggregate emissions of ozone
forming volatile organic compounds from such vehicles when using
baseline gasoline9.'' Similarly, a 25% reduction in emissions of
toxic air pollutants is required. The Act also specifies that the
Administrator may adjust the 25 percent reduction level to provide for
lesser or greater reductions based on technological feasibility, giving
consideration to the cost of achieving such reductions. In no case can
the required reduction be less than 20 percent. The Act further
provides that emissions of oxides of nitrogen (NOX) cannot
increase as a result of the use of reformulated gasoline. These VOC and
toxics reductions and NOX limit are known as the Phase II
reformulated gasoline standards.
---------------------------------------------------------------------------
\8\According to section 211(k)(10)(A) of the Act, ``baseline
vehicle'' means representative model year 1990 vehicles.
\9\The formulation for summertime baseline gasoline is defined
in section 211(k)(10)(B) of the Act. See further discussion of
baseline emissions in section IV.
---------------------------------------------------------------------------
Section 211(c) of the Act allows the Administrator to regulate
fuels or fuel additives if ``any emission product of such fuel or fuel
additives causes, or contributes to, air pollution which may reasonably
be anticipated to endanger the public health or welfare.'' Section
211(c)(2) further provides that EPA cannot control these fuels and fuel
additives ``except after consideration of all relevant medical and
scientific evidence available * * *, including consideration of other
technologically or economically feasible means of achieving emissions
standards.'' In addition, EPA must find that the prohibition ``will not
cause the use of any other fuel or fuel additive which will produce
emissions which will endanger the public health or welfare to the same
or greater degree than the use of the [regulated fuel/fuel additive].''
EPA has elected to use this authority to require reformulated fuels
to also achieve NOX reductions in order to reduce ozone formation,
based on scientific evidence regarding the benefits of NOX control
and on the cost-effectiveness of NOX reductions. The determination
of the need for, scientific justification of, and cost-effectiveness of
NOX control is presented in the RIA and summarized in subsection
C.2 below.
2. Proposal
EPA proposed a range of VOC and toxics performance standards for
Phase II reformulated gasoline, covering a variety of options for
setting these standards [see the Notice of Correction for the Proposed
Rule 58 FR 17175 (April 1, 1993)]. The proposed VOC standards ranged
between 29.7 and 37.7 percent reduction in emissions for VOC control
region 1 areas (Class A and B, the southern areas of the country) based
on a baseline fuel with an RVP of 8.7 psi10, and between 26.7 and
34.7 percent reduction for VOC control region 2 areas (Class C, the
northern areas of the country) [58 FR 17178, 17179, 17180 (April 1,
1993)]. These percentage reductions are in comparison to the emissions
performance of baseline vehicles operating on baseline gasoline; the
proposed version of the complex model was used to establish a fuel's
emissions performance. In proposing the range of values EPA considered
the costs of VOC control, the cost-effectiveness of the controls, the
health and environmental effects, energy impacts, and technological
feasibility.
---------------------------------------------------------------------------
\1\0Relative to a baseline fuel including an RVP of 7.8 psi, the
proposed VOC standards ranged between 20.7 and 31.7 percent
reduction.
---------------------------------------------------------------------------
EPA's analysis showed that fuels meeting the proposed VOC and
toxics standards were expected to show no increase in NOX
emissions, and in fact would likely achieve some reduction in NOX.
Based on the expected benefits of NOX reduction, and considering
various other factors, EPA also proposed NOX emissions reduction
standards for Phase II reformulated gasoline based on the authority of
section 211(c)(1)(A) of the Act. The proposed NOX standards ranged
from 0 to 14.8 percent reduction for VOC control region 1 (southern
areas) and 0 to 15.4 percent reduction for VOC control region 2
(northern areas) [58 FR 17178-9 (April 1, 1993)]. Again, the NOX
emissions performance of a fuel would be determined using the proposed
complex model. The range of proposed standards was based, in part, on
different levels of potentially acceptable cost-effectiveness as well
as whether the cost-effectiveness was calculated based on reductions in
NOX emissions alone or on the combined reduction in VOC and
NOX emissions.
EPA proposed alternative VOC standards that would apply depending
on whether EPA adopted a NOX reduction standard. These were based
on changes in the cost-effectiveness analysis from combined VOC plus
NOX emissions reductions. As explained in the proposal, measures
taken to achieve the NOX reductions under this option would result
in VOC emission reductions incremental to those obtained under the
proposed VOC only standards, which were based solely on the cost per
ton of VOC reduced. These additional VOC emission reductions obtained
through a combined VOC plus NOX standard presented the option of
setting a standard for larger VOC reductions. EPA analyzed the cost-
effectiveness of a more stringent VOC standard in connection with a
NOX standard, and proposed a range of values depending on the
target cost-effectiveness level: for southern areas, 29.7-40.2 percent
based on an 8.7 psi baseline RVP (20.7-33.8 percent reduction based on
a 7.8 psi baseline RVP); for northern areas, 26.7-37.3 percent
reduction.
In analyzing potential VOC and NOX reduction requirements, EPA
looked at two potential cost-effectiveness targets: $5,000/ton and
$10,000/ton. These figures were selected as representative of the range
of cost-effectiveness for controls which would be incurred by many
ozone nonattainment areas in achieving attainment. In addition, they
reflected higher cost-effectiveness values than those for any then-
existing federal nationwide motor vehicle or motor vehicle fuel control
programs.
Finally, EPA proposed a toxics emissions reduction standard between
20 and 25 percent. The 25 percent reduction standard proposed was based
on the level specified in section 211(k)(3)(ii) of the Act. In the
proposal, EPA recognized that while on average this level of toxics
control was cost effective, it could be highly cost ineffective for
some refiners. The statutory minimum 20 percent reduction standard was
proposed as an alternative to allow refiners further flexibility in
meeting the VOC and NOX standards (and for some to reduce the need
for capital intensive modifications specific to toxics control), under
circumstances where in most cases large reductions in toxics emissions
would automatically result from the VOC and NOX controls.
3. General Comments Received on Proposal
EPA received several comments recommending a reproposal of the
Phase II standards once the complex model was finalized and EPA could
develop a single standard for each pollutant. One comment stated that
the construct of the complex model will have a significant effect on
the standards, and it was therefore not possible to comment on the
costs or performance of the Phase II standards as proposed (since they
were not based on the final complex model). Others commented that it
was improper to establish standards until the model that predicts
benefits exists. EPA does not believe it is necessary to repropose
these standards, since the proposal presented a range of values for the
standards and outlined all of the options that were considered. The
final standards were derived based on the final complex model, so the
standards include the effect of the complex model on the emissions
reductions predicted. EPA had proposed, and it was agreed in Reg-Neg,
that the Phase II standards would be promulgated with the complex
model.
Briefly described below are the factors EPA considered in setting
the standards being promulgated today, the methodology used in
determining the cost-effectiveness of fuel controls, and the reasoning
used in determining the standards. The full analysis leading to the
final standards is more thoroughly discussed in section VI of the
regulatory impact analysis (RIA) associated with this rulemaking.
B. Factors Affecting Selection of the Phase II Standards
In determining the Phase II reformulated gasoline standards, EPA
considered the health, environmental, and energy impacts, as well as
the cost and the technological feasibility of reformulating gasoline to
attain emission reductions of VOCs, toxics, and NOX. EPA's
analyses of these factors are discussed briefly below, and in detail in
the RIA.
1. Health and Environmental Impacts
The purpose of the reformulated gasoline program is to reduce motor
vehicle emissions of ozone forming VOCs and certain specified toxic air
pollutants in those areas most in need of such reductions. As discussed
above, EPA is also reducing ozone forming NOX emissions from RFG
as a part of this rulemaking. EPA measured the health and environmental
benefits of the reformulated gasoline program in terms of the number of
tons of VOC, NOX, and toxics reduced, since the Act specifies
mass-based emissions reductions. The benefits of toxics reductions were
further evaluated on the basis of the number of cancer incidences
avoided, since this is a common measure of the effectiveness of toxics
control. The reader is directed to section C below for quantified
estimates of these reductions.
The benefits of ozone reduction will be gained through the
reduction of both VOC and NOX emissions. Ambient ozone levels and
the effect of VOC emission reductions on these levels vary from city to
city, making it difficult to quantify the benefits of the VOC reduction
beyond tons of emissions reduced. In general, reductions in VOC
emissions will improve the air quality of most affected areas and
thereby reduce the negative health impacts of exposure to high levels
of ozone. Visibility and other environmental measures are also improved
through reductions in emissions of ozone precursors. Similar benefits
will be gained through reductions in NOX emissions. The reader is
directed to subsection C.2 for further discussion on the health and
environmental benefits of NOX control.
Reducing ozone levels in highly populated urban areas would help to
reduce short-term health effects such as impaired lung function, cough,
nausea, chest pain, throat irritation, increased susceptibility to
respiratory infection, and increased sensitivity of asthmatics to
allergens (e.g., pollen) and other bronchoconstrictors. Long-term
health effects of exposure to ozone include accelerated aging of the
lungs, reduced elasticity of the lungs, scarring of lung tissue, and
permanent reductions in baseline lung function.
Although the reformulated gasoline program is concentrated in urban
areas, some reformulated gasoline will be used in rural areas as a
result of spillover in the distribution system. Reducing ozone levels
in rural areas would enhance agricultural crop yield, currently
estimated to be reduced by as much as $2-3 billion per year by existing
ozone concentrations.11 In addition, lower ozone levels would help
reduce damage to forest ecosystems which experience lower tree growth
rate, foliage damage, and increased susceptibility to stress (e.g.,
insects, disease, drought) caused by current tropospheric ozone
levels.12
---------------------------------------------------------------------------
\1\1U.S. EPA, ``Air Quality Criteria for Ozone and Other
Photochemical Oxidants,'' EPA Report No. EPA-600/8-84/020A-E, p.1-
27.
\1\2Ibid., p. 7-1 through 7-4.
---------------------------------------------------------------------------
Reductions in mobile source emissions of the air toxics addressed
in the reformulated gasoline program (benzene, 1,3-butadiene,
formaldehyde, acetaldehyde, and POM) may result in fewer cancer
incidences. A number of adverse noncancer health effects have also been
associated with exposure to air toxics, particularly with higher level
exposures experienced in particular microenvironments such as parking
garages and refueling stations. These other health effects include
blood disorders, heart and lung diseases, and eye, nose, and throat
irritation. Some of the toxics may also be developmental and
reproductive toxicants, while very high exposure can cause effects on
the brain leading to respiratory paralysis and even death. The use of
reformulated gasoline meeting the Phase II standards will likely help
to reduce some of these health effects, as well. A more thorough
discussion of the variety of possible non-cancer effects of concern
from exposure to air toxics is contained in EPA's Motor Vehicle-Related
Air Toxics Study.13
---------------------------------------------------------------------------
\1\3EPA document 420-R-93-005, April 1993.
---------------------------------------------------------------------------
The emissions reductions and cancer incidences avoided as a result
of today's standards are discussed below in section C.
In addition to the benefits from reductions in emissions of VOC,
NOX, and toxics, other environmental benefits will be realized as
a result of the use of reformulated gasoline. Emissions of carbon
monoxide will decrease as the result of adding oxygen to the fuel, to
the benefit of areas out of attainment for this air pollutant and to
human health in general.14 In addition, since reformulated
gasoline is projected to cost more than conventional gasoline, it is
possible that consumers will purchase and, thus, use less gasoline,
resulting in fewer overall emissions due to mobile sources.
---------------------------------------------------------------------------
\1\4Most of this benefit will occur as a result of the use of
oxygen in Phase I RFG, not from the Phase II reductions.
---------------------------------------------------------------------------
2. Energy Impacts
Production of Phase II reformulated gasoline subject to performance
standards for VOC, NOX, and toxics will require an increase in the
amount of energy used at the refinery. An estimate of the energy used
depends on many factors, including how the energy balance is evaluated,
the type and source of oxygenate, the refinery configuration, and the
reformulation approach. Determining an exact energy increase associated
with reformulated gasoline production (on the basis of a constant level
of gasoline energy produced) is difficult.
As later sections of this document will show, the standards for VOC
and NOx reduction promulgated today will likely be met largely
through reductions in the sulfur content and Reid vapor pressure (RVP)
of the fuel. The process used to remove sulfur from gasoline,
hydrodesulfurization, is an energy intensive process; mainly due to the
need for and consumption of hydrogen. The energy impact will depend on
the sulfur level of the crude used by the refinery and the level of
sulfur control necessary for that refinery to meet the standards.
Reducing the RVP of the fuel requires removal of the lighter compounds
in the fuel, also an energy consuming process. Overall, it is expected
that the energy consumption by refineries in producing Phase II
reformulated gasoline will increase slightly (perhaps a couple percent)
over the level of energy used to make Phase I RFG, but the magnitude of
this increase is difficult to measure due to the many variables
involved.
3. Technological Feasibility
EPA also considered the technological feasibility of producing
fuels to meet the Phase II standards. EPA believes that the refinery
modeling results (from which the fuel parameter control costs were
estimated) indicated that it is technologically feasible to make the
fuel parameter changes that were analyzed in developing the standards.
The refinery models utilize only well-developed, demonstrated,
commercially available technologies, and are designed to only model
fuels within the limits of these technologies.15 Given the cost
incentives created by this rulemaking, in all likelihood new
technologies will be developed between now and the year 2000 which will
reduce the costs for certain types of fuel parameter changes. Thus, EPA
believes that the determination of fuel parameter control costs using
the results of the existing refinery models is reasonable, that the
costs generated are perhaps conservative, and that the technological
feasibility of producing such emission-reducing fuels is justifiable.
This position was supported by many of the comments received. While
other commenters questioned the costs used in developing the proposal
(as discussed in subsection 4.b), no comments questioned the
technological feasibility of these refinery configurations.
---------------------------------------------------------------------------
\1\5See the RIA for additional details on the refinery models
used for this analysis.
---------------------------------------------------------------------------
Because the standards promulgated today will not take effect until
the year 2000, and because all the processes needed to produce
complying fuels are already commercially available, EPA does not
believe that lead time will be an issue in achieving the required
emissions reductions.
4. Fuel Safety and Driveability
EPA evaluated safety concerns associated with the use of low RVP
fuels and found no significant negative impacts, as discussed in the
RIA. Comments also raised concerns about driveability problems arising
from the use of low RVP fuels. They raised concerns that EPA's analysis
in the proposal did not address spring months (the transition time to
the VOC control period), September RVP fuel sold in October, and low
RVP gasoline sold in low temperature areas near nonattainment areas.
While neither EPA nor any other organization conducted driveability
testing at low ambient summer temperatures, EPA has looked at the
actual vapor pressure of fuels currently in production, as documented
in the draft RIA.16 Based upon a comparison of actual vapor
pressures, EPA believes that 6.5 psi RVP fuel in the summer should have
similar driveability to current winter fuels. At this time EPA believes
there should be no significant driveability problems with gasoline at
an RVP level down to 6.5 psi. Until such time as data can be gathered
to more fully evaluate the driveability impacts of low RVP fuels, EPA
believes that 6.5 psi may present a practical lower limit below which
the existence of adverse driveability impacts is unknown. Discussions
with representatives of both the oil and automotive industries
reflected a similar uneasiness in going below 6.5 psi RVP given the
lack of data at lower levels. However, the standards for Phase II RFG
are performance based standards. As a result, flexibility exists for
refiners to meet the Phase II standards, without reducing the RVP of
the gasoline below 6.5 psi.
---------------------------------------------------------------------------
\1\6``Draft Regulatory Impact Analysis for the Notice of
Proposed Rulemaking of the Complex Model, Phase II Performance
Standards, and Provisions for Renewable Oxygenates,'' February 5,
1993.
---------------------------------------------------------------------------
5. Cost-Effectiveness of Emissions Reductions
a. Introduction. For purposes of this discussion, EPA defines cost-
effectiveness as the ratio of the incremental cost of a control measure
to the incremental benefit, e.g., tons of VOC or other emissions
reduced. Considering cost-effectiveness allows the Agency to develop a
relative ranking of various ozone and toxics control strategies so that
an environmental goal can be achieved at minimum cost. As the cost-
effectiveness of an emission reduction strategy increases, it may be
possible to achieve similar, substantial emission control in other ways
(e.g., through other regulatory programs) at the same or lower cost per
unit of benefit. EPA therefore considered cost-effectiveness in
deciding what VOC, NOx, and toxics control, if any, to impose
beyond the minimum levels required under section 211(k)(3)(B).
One commenter recommended that EPA evaluate the cost-effectiveness
of this program separately for small and large refiners, and also that
EPA consider granting small refiners more time to comply with the
requirements (as is allowed by California for California reformulated
gasoline). The California reformulated gasoline program requires all
refiners selling gasoline in the state to produce reformulated
gasoline, and thus does not afford any flexibility to refiners, large
or small. The federal RFG program, however, does not require 100%
production of RFG in any region, nor does it require that every refiner
produce RFG. Hence, small refiners can choose not to produce RFG and
instead supply conventional gasoline if the costs of complying with the
program are too burdensome. For those small refiners electing to
produce RFG, the option to select between per gallon and averaging
standards, as well as the ability to set their own baselines, gives
them flexibility to meet the standards in the manner that is most cost
effective for them. Furthermore, the enforcement structure is based on
a single set of standards for Phase II RFG. Allowing some refiners to
comply with a different set of standards would require additional and
more complicated enforcement provisions, and could jeopardize the
fungibility of reformulated gasolines.17 Since EPA believes that
the existing program provides sufficient flexibility to small refiners,
there is no need to pursue multiple enforcement programs. See section
XV for additional discussion of the impact of this rule on small
refiners.
---------------------------------------------------------------------------
\1\7For Phase I RFG, the standards are set at the statutory
minimum for both VOCs and toxics. EPA could not lawfully allow small
refiners less stringent standards or more time to comply with the
Phase I standards.
---------------------------------------------------------------------------
b. Fuel Parameter Control Costs. Fuel parameter control costs and
interrelationships between fuel parameters are integral parts in the
evaluation of the cost-effectiveness of Phase II RFG controls. The
costs and interrelationships used to develop the VOC and toxics
standards were estimated from the results of refinery modeling
performed by Bonner and Moore Management Science,18 by Turner,
Mason, and Co. for the Auto-Oil Air Quality Improvement Research
Program;19 by Turner, Mason, and Co. for the Western States
Petroleum Association (WSPA);20 and by EPA in-house (using the
Bonner and Moore refinery model).21 EPA used these regional
refinery models to estimate the cost and interrelationships of various
fuel parameter controls. The final average nationwide costs were
obtained by weighing the regional values by the estimated fraction of
total reformulated gasoline (RFG) production in each region.
---------------------------------------------------------------------------
\1\8Bonner and Moore Management Science, ``Study of the Effects
of Fuel Parameter Changes on the Cost of Producing Reformulated
Gasoline,'' Prepared for EPA under contract through Southwest
Research Institute and the National Institute for Petroleum and
Energy Research. This data, as well as data generated by EPA in-
house, was made available to the public through the following
document: ``DOE and API Phase II Cost Estimates,'' EPA Memorandum
from Lester Wyborny, FSSB, to the Air Docket, November 4, 1993.
\1\9``Costs of Alternate Gasoline Reformulations, Results of
U.S. Refining Study,'' Turner, Mason & Co. for the Economics
Committee of the Auto/Oil Air Quality Improvement Research Program,
April 1992.
\2\0``WSPA Study of the Cost Impacts of Potential CARB Phase 2
Gasoline Regulations,'' Turner Mason & Company for the Western
States Petroleum Association, November 18, 1993.
\2\1``Aromatics and E200 Reformulation Costs,'' Memorandum from
Lester Wyborny, EPA, to the Air Docket, December 10, 1993.
---------------------------------------------------------------------------
Many comments were received on the costs used in the proposal. Some
of these comments, and EPA's response, are summarized here, while the
RIA contains a complete discussion and analysis of the comments
received. Several commenters questioned the appropriateness of using
independent refinery models to generate costs for control of individual
parameters. In addition, they questioned the aggregation of results
from regional models to generate national average costs, and
recommended instead using a model from the region likely to realize the
highest costs for producing reformulated gasoline (PADD 1). While using
regional models to estimate national average costs requires an
acknowledgment of the inherent limitations in such models, EPA believes
that it is appropriate to use them for the purpose of determining the
costs to produce reformulated gasoline. The limitations and assumptions
made in using the refinery models and the results of this analysis are
discussed in detail in the RIA.
The manufacturing cost of producing gasoline is the sum of the
capital recovery cost and the operating costs, adjusted for changes in
the energy content of the fuel (to represent consistent fuel economy).
VOC control is mandated only during the high ozone season, and thus all
costs were allocated to the high ozone season in the refinery modeling
work. In contrast to VOC control, toxics control and the benefits from
reductions in toxics emissions occur year-round. Although the costs of
toxics control should be determined on an annual basis, EPA used the
same costs that were used for the VOC analysis, since it had been
determined in the RIA (and supported by many comments received) that
additional toxics control would be highly cost-ineffective. The level
of either VOC or toxics control that is cost effective is not greatly
affected by the accuracy of the costs, due to the magnitude of
reductions achieved.
Some comments received on the proposal raised the concern that this
method of determining costs did not accurately reflect all of the costs
of the program, since the ``compliance costs'' for record keeping and
enforcement, as well as costs incurred by pipelines or other entities,
were not included. While it is true that ``compliance costs'' will be
incurred as a result of the reporting and enforcement requirements of
Phase II RFG, EPA does not anticipate the costs to be greater than
those incurred by the Phase I RFG program. Refiners will already be
supplying the information required by EPA for Phase I, and will
continue to do so under Phase II. Hence, there is no additional cost of
compliance to add to the costs of Phase II RFG.
Other factors affecting incremental fuel parameter control costs
include the amount of reformulated gasoline produced by the refinery
and the effects of fuel parameter changes on fuel economy. Because
producing reformulated gasoline reduces flexibility in refinery
operations, the cost of producing such fuels increases with the amount
of reformulated gasoline that is produced in a given refinery. In this
analysis, EPA used a scenario of RFG production based on participation
in the reformulated gasoline program by the nine mandated areas, those
areas which had opted into the program as of August 14, 1993 (the close
of the comment period on the proposal), the entire Northeast Ozone
Transport Region (including both attainment and nonattainment areas),
and all other ozone nonattainment areas. This scenario was chosen to
represent the Phase II RFG program that would result if all eligible
areas opted into the program. Since the Ozone Transport Commission has
not announced plans to opt-in to the RFG program, and the only
additional nonattainment areas that have opted into the program since
August 14 are those located in Kentucky, the volume of RFG production
used for this analysis is overstated by about 20 percentage points. As
a result, the cost estimates are higher than will likely be
experienced, since use of RFG in the entire Northeast would severely
limit refinery production in that region, incurring somewhat higher
costs to individual refiners, particularly to those refiners which for
economic reasons would choose not to produce RFG and merely continue
producing conventional fuel.
EPA evaluated the costs for incremental control levels for a
variety of fuel parameters. This evaluation revealed that the greater
the level of control, the higher the costs of achieving that level.
Complete information on the development of the individual parameter
costs is provided in the RIA.
Several comments were received questioning the validity of
evaluating the cost-effectiveness of Phase II RFG on a parameter by
parameter basis. The recommended alternative was to evaluate the cost
of producing a gasoline meeting the standards for a variety of refinery
configurations, and to use this information to determine the cost-
effectiveness of the standard. As explained in the RIA, EPA determined
that it was appropriate to evaluate cost-effectiveness on an
incremental basis to properly compare fuel controls to other forms of
emission control.
c. Emissions reductions.--In determining the emission reductions
and the associated cost-effectiveness of VOC control, EPA employed a
convention typically used in estimating the benefit of both mobile and
stationary source VOC controls. This convention requires the
determination of cost-effectiveness on the basis of annual tons of VOC
reduced. Thus, even though VOC emission reductions required under
section 211(k) occur only during the high ozone season, the convention
is to calculate the cost of the fuel parameter control per ton of VOC
removed as if the high ozone season emission reductions were spread
over the whole year. Comments were received that questioned the
appropriateness of evaluating the cost-effectiveness on an annualized
tons reduced basis rather than on a summer tons reduced basis, since
the program is a summer program. The purpose of applying this
convention to the evaluation of Phase II RFG was to allow direct
comparison of the cost-effectiveness of this program with the cost-
effectiveness of other VOC control strategies, which is typically
calculated on a year-round basis. The only other appropriate
alternative would be to recalculate the cost-effectiveness of all other
programs on the basis of cost per ton of control during the high ozone
season, the only time period when emission reductions for the purposes
of ozone control are of any significant value.
Reductions in emissions of both exhaust and evaporative VOC are
determined for a given fuel parameter change using the complex model.
As discussed in earlier sections, the complex model statutory baseline
emissions are based on 1990 vehicle technology, and compliance with the
Phase II standards is measured relative to these base emissions. As
explained in the RIA, EPA determined that the olefin level specified in
the statutory baseline was not representative of the actual olefin
level of gasoline in 1990. Phase I RFG includes no specific limits on
olefins, and thus refiners can meet Phase I standards (under the
complex model) by controlling any fuel parameters. However, refiners
whose olefin baseline is significantly higher than the statutory level
may need to reduce olefins to meet the no NOx increase
requirement, putting them at a competitive disadvantage because olefin
control is costly. Hence, using data from Bonner and Moore modelling as
well as fuel surveys from cities across the country, the baseline
olefin level was reevaluated and set at 13.1 vol% for the purposes of
determining cost-effectiveness.
Although the standards require reductions for baseline vehicles
relative to the emissions from the statutory baseline fuel, the cost-
effectiveness of a given fuel parameter control is measured based on
actual, i.e., in-use emission reductions. For this reason, EPA
determined the cost-effectiveness of fuel parameter changes relative to
the incremental in-use emissions. The baseline in-use emissions were
determined for 2003, a typical post-1999 year, using MOBILE5a with
enhanced inspection and maintenance (I/M), as discussed in section
IV.22 Exhaust and evaporative percent reductions for in-use
emissions are determined separately by applying the percent reduction
in emissions predicted by the complex model to the in-use emissions,
and then totalled to get total in-use emissions reductions. The cost,
emissions reductions, and cost-effectiveness of incremental changes in
fuel parameters for Phase II RFG is calculated relative to Phase I RFG.
---------------------------------------------------------------------------
\2\2Following the precedent set in the proposal, the in-use
baseline for VOC Control Region 1 areas included an RVP of 7.8 psi.
The standards set today are based on reductions relative to the
statutory baseline fuel with an RVP of 8.7 psi, however.
---------------------------------------------------------------------------
To determine the cost-effectiveness of the toxics standard, EPA
employed the convention of basing cost-effectiveness on the number of
cancer incidences avoided. The number of cancer incidences avoided is
determined based on the reduction in emissions of each regulated air
toxic. The complex model was used to calculate the annual reduction in
both exhaust and evaporative emissions of each toxic for each fuel
reformulation. Each toxic emission has a different unit risk factor,
defined as the number of cancer incidences per year per gram-per-mile-
emission per person. Therefore, the emissions of each toxic pollutant
were converted to an estimate of annual cancer incidences using the
risk factor for that pollutant and the population of the participating
reformulated gasoline areas. The total cancer incidences resulting from
the total toxics emissions were then calculated by summing the cancer
incidences for the individual toxics.
d. Cost-effectiveness. The costs and emissions reductions for each
parameter change are combined to determine the incremental cost-
effectiveness ($/ton) of each level of control, assigning all of the
costs to the control of the pollutant of concern (VOC or NOX).
Several comments were received regarding this method of establishing
cost-effectiveness. One comment suggested that refiners are likely to
reduce parameters to levels lower than the mandated limits to ensure
compliance with the standards. Thus it was suggested that the cost
analysis should be based on a marginal increase in the standard to
determine the true cost-effectiveness of the program. EPA's cost-
effectiveness analysis is inherently an averaging analysis, however,
since the cost estimates are based on the responses of average regional
refineries to changes in fuel composition. Averaging allows refiners to
be high or low for any batch of fuel, as long as their average meets
the standard over the course of the entire compliance period.
Measurement error goes both above and below the true values on any
given batch of fuel, but should average zero over the course of many
batches. As a result, there is no need for a compliance margin in
setting an averaging standard.
EPA proposed a range of VOC and NOX emission reduction
standards based, in part, on two possible benchmarks for cost-
effectiveness, $5,000/ton and 10,000/ton.23 Several commenters
stated that $5,000/ton was most appropriate, particularly in light of
the inaccuracies in the cost analysis. Some commenters believed that
$5,000/ton was too high compared to alternate control strategies, while
others stated that this was reasonable compared to other strategies
currently required.
---------------------------------------------------------------------------
\2\3As discussed later, EPA considered a number of issues,
including flexibility of refiners and burden to the industry, in
addition to cost-effectiveness when setting the Phase II RFG
standards.
---------------------------------------------------------------------------
Upon review of the costs of other VOC and NOX control programs
(see subsections C.1 and C.2 below), EPA believes that a cost-
effectiveness benchmark of $10,000/ton is too high at this point in
time and that a cost-effectiveness of approximately $5,000/ton is more
appropriate for the Phase II VOC standard and the accompanying NOX
standard. The standards presented today fall within this guideline.
The cost-effectiveness of toxics control was similarly determined
as the ratio of the total incremental cost for the incremental
reduction in emissions to the total tons of toxics reduced. The cost-
effectiveness of toxics control was also calculated as the ratio of
total costs to incremental reductions in cancer incidences. EPA's
proposal did not include any benchmark limits for the cost-
effectiveness of toxics control, but did acknowledge that in most cases
control above the statutory minimum was not cost-effective. This
conclusion was supported by the comments received, and by the final
analysis presented here.
C. Phase II Reformulated Gasoline Standards and NOX Standards for
Reformulated Gasoline
The following sections explain the development of the VOC standards
for Phase II reformulated gasoline, and the NOX standards EPA is
setting for gasoline sold in RFG areas after 1999. The final standards
are summarized in subsection 3 below.
1. VOC Standards Development
Table VI-1 shows the incremental fuel parameter control costs,
emissions reductions, and cost-effectiveness calculated by EPA for use
in setting the VOC emissions standards. The specific fuel parameter
changes shown in the table are only examples; refiners may achieve the
required standards by any combination of fuel component controls
resulting in the required emissions performance. EPA received
conflicting comments regarding which parameters would likely be
controlled to meet the proposed standards in a cost effective manner.
As demonstrated in the RIA, EPA has used all available information to
determine which parameters can be controlled in a cost effective manner
to achieve VOC emission reductions.
Table VI-1.--Fuel Parameter Control Costs and VOC Reductions\1\
------------------------------------------------------------------------
Incremental
Fuel parameter cost ( Cumulative Incremental Incremental
control cents/gal) reduction cost-eff. to phase I
(%) ($/ton) ($/ton)
------------------------------------------------------------------------
Phase I--RVP: 8.0
psi, Oxygen:
2.1wt%, Benzene:
0.95%:
RVP to 7.1 psi.. 0.18 22.9 400 400
RVP to 6.7 psi.. 0.08 25.5 600 400
Sulfur to 250
ppm............ 0.12 \2\26.1 3,700 600
Sulfur to 160
ppm............ 0.56 27.1 11,000 1,300
Sulfur to 138
ppm............ 0.24 27.4 19,000 1,600
Sulfur to 100
ppm............ 0.52 27.8 24,000 2,300
Olefins to 8.0
vol%........... 0.78 26.2 (-) 3,700
Aromatics to 20
vol%........... 2.01 27.8 24,000 6,000
Oxygen to 2.7
vol%........... 0.61 28.2 28,000 6,600
Olefins to 5.0
vol%........... 2.77 27.4 (-) 11,000
E300 to 88%..... 0.35 27.4 48,000 11,000
E300 to 91%..... 2.01 27.5 198,000 14,000
E200 to 44%..... 0.38 27.7 37,000 14,000
E200 to 47%..... 1.32 28.4 36,000 15,000
E200 to 50%..... 2.97 29.0 96,000 18,000
------------------------------------------------------------------------
\1\Based on costs and emissions reductions for VOC control region 2
(northern areas). Assumes all costs allocated to VOC control.
\2\RVP control down to 6.5 psi, the limit considered reasonable at this
point in time for driveability purposes, would increase this value to
27.2% at a similar cost-effectiveness level.
As the information in the Table VI-1 shows, RVP control down to 6.7
psi achieves virtually all of the VOC emission reductions that are
achievable at less than $5,000 per incremental ton of VOC
reduced.24 Sulfur can be reduced to a level of approximately 250
ppm at an incremental cost-effectiveness of less than $5,000 per ton,
gaining an additional 0.6% VOC reduction, to achieve a total reduction
(on average) of 26.1%. RVP could also be reduced further to 6.5 psi,
the level currently considered a reasonable limit for driveability
purposes, to obtain an additional 1.1% reduction (for a total of
27.2%). Incremental changes in fuel parameters other than RVP have only
a marginal effect on VOC emissions and can be very costly; less than an
additional one percent reduction would be achieved at a significantly
higher incremental cost of over $10,000/ton VOC. In spite of the
uncertainty in the cost estimates used, the level of VOC control that
is cost effective is relatively insensitive to variations in cost due
to the fact that anything other than RVP and the first increment of
sulfur control causes the costs to escalate dramatically, making
control of other parameters cost ineffective.
---------------------------------------------------------------------------
\2\4Note that the cost of this level of reduction incremental to
the emission reductions achieved by Phase I RFG is significantly
less than $1,000/ton VOC.
---------------------------------------------------------------------------
The cost-effectiveness of VOC control in Phase II RFG presented in
Table VI-1 has been compared to the cost-effectiveness of other
stationary and mobile source VOC control strategies. As summarized in
the RIA, a review of the estimated cost-effectiveness of controlling
VOC emissions from stationary sources yielded a wide range of values.
Many of the existing VOC control strategies have minimal costs or even
result in savings. However, a number of VOC control options have
significant costs associated with them. For example, the estimated
cost-effectiveness of reducing emissions from automobile and light
truck coating operations in assembly plants is $1,000-4,000/ton VOC.
Reducing emissions from the production of pneumatic rubber tires is
estimated to cost between $150 and $18,800 per ton of VOC reduced,
depending on the operation to which control is applied. Control of
emissions from floating roof tanks used for storage of petroleum
liquids can cost up to $3,700/ton VOC reduced. Reducing emissions from
the production of high density polyethylene, polypropylene, and
polystyrene resins can cost between $1,000 and $3,000/ton VOC reduced
depending on the level of control.
Control of VOC emissions from mobile sources similarly is estimated
(see the RIA) to result in a wide range of cost-effectiveness values,
depending on the type of program and level of control achieved.
Enhanced inspection and maintenance (I/M) programs will cost between
$900-1,700/ton VOC reduced, while basic I/M was estimated to cost
$5,400/ton VOC.25 The Tier 1 standards for light duty vehicles
(already implemented for the 1994 model year) were estimated to cost
about $6,000/ton VOC.
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\2\5``Inspection/Maintenance Program Requirements,'' Final Rule,
57 FR 52984, November 5, 1992.
---------------------------------------------------------------------------
2. NOX Standards Development
While section 211(k)(2)(A) of the Act specifies that there be no
net increase in NOX emissions (over baseline levels) resulting
from the use of reformulated gasoline, both a National Research Council
study26 and a study prepared for EPA27 have indicated that
additional NOX reductions could significantly reduce ozone
formation in many areas. Gasoline vehicles contributed 20-35% of total
urban NOX inventories in 1990 and are expected to contribute
similar amounts in 2000.28 As identified in subsection A.1 above,
section 211(c) of the Act gives the Agency broad regulatory authority
to regulate motor vehicle fuel quality if any emission product of such
fuel causes or contributes to air pollution which may reasonably be
anticipated to endanger public health or welfare. Based on the reports
cited above, other EPA work in ambient ozone analysis, and the
authority granted EPA under section 211(c), EPA proposed setting a
NOX emission reduction standard in connection with the Phase II
standards to further reduce ozone formation during the high ozone
season.
---------------------------------------------------------------------------
\2\6 ``Rethinking the Ozone Problem in Urban and Regional Air
Pollution,'' National Research Council, December 18, 1991.
\2\7 ``Modeling the Effects of Reformulated Gasolines on Ozone
and Toxics Concentrations in the Baltimore and Houston Areas,''
prepared for EPA,OPPE,APB by Systems Applications International,
September 30, 1992.
\2\8While Tier I vehicles, which have lower NOX emissions
than conventional vehicles, will be entering the fleet, they will
have only had five years to displace older, dirtier cars by 2000.
Anticipated growth in vehicle miles travelled will offset any
emissions benefits gained from the use of cleaner cars.
---------------------------------------------------------------------------
A number of aspects of the RFG program lead naturally to a focus on
NOX control. First, Phase II RFG is focused on the worst ozone
nonattainment areas. Second, these areas will be required to use VOC
controlled Phase II RFG only during the time of the year when control
is needed (the summer months). Third, special fuel distribution for RFG
will already be in place in these areas; many of the costs of producing
and distributing this new gasoline will have been incurred as a result
of the Phase II program. Fourth, EPA has shown (in the RIA and the
following sections) that gasoline can be refined cost-effectively to
reduce NOX emissions.
EPA sees little benefit in creating a second gasoline program,
which would likely differ only slightly from RFG in the geographic
areas affected, to control NOX emissions. A large segment of the
industry is already making the changes necessary to comply with the
Phase I RFG standards in 1998 relative to the statutory baseline for
sulfur and olefin levels (and all other parameters defined). Therefore,
many refiners will be assessing the need for sulfur and olefin control
in the next few years to ensure they comply with the no NOX
increase requirement of the Act. Promulgated separately, a NOX
standard would require refiners to make changes to their refineries in
addition to those already made to comply with Phase I RFG and the Phase
II VOC and toxics standards, perhaps making some of the original
refinery changes obsolete. By enacting a NOX emissions reductions
program at this time EPA hopes to avoid this concern. EPA believes that
in locations where reformulated gasoline is found necessary to reduce
the formation of ozone, a NOX standard is appropriate as well, as
discussed below and in Section VI of the RIA.
The Agency received many comments about the proposed NOX
standards. Some commenters claimed it was counter to the regulatory
negotiation agreement. This concern has been addressed in section A
above. Others felt that NOX control should be considered on a
local basis to meet local needs and thus should not be part of a
national fuel program. Another stated that states should have to
demonstrate the need for mobile source NOX control before EPA
required it. Some commenters supported NOX control based on the
cost-effectiveness analysis presented in the proposal because of the
similarity with the costs of other current NOX control programs.
One comment suggested that EPA control NOX by eliminating the
oxygen requirement using the authority granted in section 211(k)(2)(A).
It was also questioned whether EPA had satisfied the requirements to
use the authority granted in section 211(c) regarding the supporting
information presented in the proposal. The remainder of this section
presents EPA's response to these concerns; additional detail may be
found in the RIA.
a. Scientific justification for NOX control. As discussed in
the RIA, a recent study by the National Research Council (NRC)
indicated that VOC control alone is of minimal benefit to ozone
nonattainment areas such as Houston which have high VOC to NOX
ratios in the ambient air.29 The NRC study and work by EPA30
and others31 have also indicated that NOX control is an
effective ozone control strategy for the northeast (including New York-
Connecticut and Boston-Maine) as well as the Lake Michigan region
(Milwaukee, Chicago, and Muskegon). In general, many studies have shown
that NOX control alone may be helpful in achieving ozone
reductions in some areas, though not necessarily in all areas, again
depending on the VOC to NOX ratios. Reductions in emissions of
both VOC and NOX should benefit all areas, however. Those areas
that do not benefit from the reduction in NOX emissions should
benefit from the large reduction in VOC emissions that will be achieved
by Phase II RFG.
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\2\9National Research Council, Rethinking the Ozone Problem in
Urban and Regional Air Pollution, National Academy Press,
Washington, D.C., 1991.
\3\0U.S. EPA, Regional Ozone Modelling for Northeast Transport
(ROMNET), EPA Report 450/4-91-002a, June 1991.
\3\1See the RIA for additional references.
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There are also non-ozone benefits of NOX control, such as
reductions in emissions leading to acid rain formation, reductions in
toxic nitrated polycyclic aromatic compounds, lower secondary airborne
particulate (i.e. ammonium nitrate) formation, reduced nitrate
deposition from rain, improved visibility, and lower levels of nitrogen
dioxide. A complete discussion of these benefits can be found in the
RIA. A NOX standard also should effectively protect against an
increase in the olefin content of the fuel, reducing concern over a
possible increase in the reactivity of vehicle emissions.
b. Consideration of section 202 motor vehicle controls. Before
controlling or prohibiting a fuel or fuel additive under section
211(c)(1)(A), the Administrator must consider ``other technologically
or economically feasible means of achieving emission standards under
section [202].'' This has been interpreted as requiring consideration
of regulation through motor vehicle standards under section 202 prior
to regulation of fuels or fuel additives under section 211(c)(1)(A)
[Ethyl Corp. v. Environmental Prot. Agcy., 541 F.2d 1, 32 (D.C. Cir.
1976)]. This does not establish a mandatory preference for vehicle
controls over fuel controls, but instead calls for the good faith
consideration of motor vehicle standards before imposition of fuel
controls [541 F.2d at 32 n.66]. This reflects Congress' recognition
that fuel controls under section 211(c)(1)(A) might logically involve
controls on fuel composition itself, while vehicle standards under
section 202 are generally performance standards, regulating vehicle
emissions and not the design or structure of the vehicle. Fuel controls
might therefore lead to greater government involvement in the
regulation of the manufacturing process than would be expected from
vehicle controls [541 F.2d at 11 n.13].
Congress addressed this concern by requiring agency
``consideration'' of vehicle standards under section 202 before
imposition of fuel controls under section 211(c)(1)(A). It is important
to note that the Administrator must in good faith consider such vehicle
controls, but retains full discretion in deciding whether to adopt
either fuel or vehicle controls, or both [541 F.2d at 32 n.66].
In evaluating motor vehicle controls under section 202 in this
context, the first major point to consider is that EPA has already
imposed more stringent NOX control standards on motor vehicles.
The Tier 1 standards for light-duty motor vehicles and trucks require
reductions in light-duty motor vehicle NOX emissions starting with
model year 1994, with a percentage phase-in of the more stringent Tier
1 standards until they apply to all new model year 1996 and later
light-duty vehicles and trucks. These vehicles are also required to
meet in-use standards.32 For heavy-duty vehicles, EPA recently
reduced the NOX standard to 4 g/bhp-hr, starting with model year
1998 [58 FR 15781, March 24, 1993]
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\3\256 FR 25724, June 5, 1991. Also, note that the Tier 1
standards apply to light-duty trucks with a loaded vehicle weight
rating of 3,750 lbs. or less.
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While these motor vehicle and motor vehicle engine controls are
expected to reduce mobile source emissions of NOX, this result is
limited by certain basic facts. First, the standards only apply to new
motor vehicles and engines. It will therefore take several years after
the first model year of the standards before vehicles and engines
certified to these standards will make up a significant portion of the
motor vehicle fleet.33 In addition, it is expected that emissions
reductions based on the reduction in the NOX standard will be
offset to a significant extent by an increase, over time, in total
vehicle miles travelled.
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\3\3As supported by the MOBILE5a model, 58 FR 29409, May 20,
1993.
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In addition to motor vehicle controls under section 202, EPA has
recently adopted or proposed other controls aimed at in-use NOX
emissions from mobile sources. The enhanced inspection and maintenance
(I/M) rules call for use of these more stringent I/M procedures
starting with 1996 [57 FR 52950, November 5, 1992]. EPA has also
proposed standards that would limit NOX emissions from new large
horsepower diesel non-road engines, pursuant to section 213 of the Act
[58 FR 28809, May 17, 1993]. While enhanced I/M programs will directly
affect the motor vehicle fleet, the non-road engine regulations are
similar to the motor vehicle regulations under section 202 in that they
would apply to new non-road engines only, and therefore involve a
certain time before a significant portion of this category of non-road
engines is replaced by new engines certified to meet the NOX
standards.
Additional mobile source controls, whether under section 202 or
under other authority such as described above, may well be cost
effective and reasonable options that EPA might decide to adopt.
However, there are certain limitations imposed by Congress on adoption
of more stringent standards (``Tier 2 standards''). For example,
Congress spelled out when and under what conditions EPA may promulgate
more stringent NOX standards for light-duty vehicles and trucks.
Congress required that EPA conduct a study on whether more stringent
standards for light-duty vehicles and trucks should be adopted, and
report back to Congress no later than June 1, 1997 [section 202(i) (1),
(2)]. Based on the study EPA must conduct a rulemaking to determine
whether there is a need for such further reductions, whether the
technology will be available for such reductions, and whether further
reductions in emissions from such vehicles will be cost effective. If
these determinations are made in the affirmative, then EPA would
proceed to promulgate emissions standards that are more stringent than
the Tier 1 standards [section 202(i)(3)(C)]. If EPA does promulgate
more stringent standards, they may not take effect any earlier than
model year 2004, and no later than model year 2006.
It is clear from this that EPA has not, at this time, completed the
lengthy process for determining whether or not more stringent standards
should be established for light-duty vehicles and trucks under section
202(i). Congress established a detailed provision spelling out the
procedures to follow and the substantive determinations that must be
made before such controls could be adopted. There is no indication, and
EPA does not believe, that these mandated procedures and criteria
preclude the exercise of discretion under section 211(c)(1)(A) prior to
completion of the rulemaking under section 202(i). Congress required
that EPA consider motor vehicle controls, but did not establish a
mandatory preference for such controls and did not preclude the
adoption of fuel controls prior to a decision on Tier 2 motor vehicle
standards.
In any case, it is clear that a decision to impose more stringent
NOX standards for light-duty vehicles and trucks under section
202(i) could not take effect prior to model year 2004. It would then
take several years before a significant portion of the in-use fleet
would include vehicles or trucks certified to a NOX standard more
stringent than the Tier 1 standard. A similar situation would apply to
a more stringent NOX standard for heavy-duty engines. The
mandatory leadtime and stability provision of section 202(a)(3)(C)
would preclude imposition of more stringent NOX standards for
heavy-duty engines until model year 2001 at the earliest. It would
again take several years before a significant portion of the in-use
heavy-duty fleet contained engines certified to a more stringent
NOX standard. For non-road engines and vehicles, EPA expects to
continue to explore NOX controls. But as with motor vehicles, any
new or more stringent NOX standards will only apply to new non-
road engines, after providing a reasonable period for leadtime. The
effect on in-use emissions is delayed based on the time needed before
new non-road engines replace earlier models.
Given these circumstances, there are several important reasons why
promulgation of a NOX reduction standard for reformulated gasoline
is important, whether or not additional vehicle or engine controls are
later adopted by the Agency. First, emissions reductions from the
NOX performance standard would start as soon as the standard is
applicable, with no delay based on fleet turnover time. Significant
NOX emission reductions would be achieved right away, in the
summer of 2000, while more stringent light-duty or heavy-duty standards
would not be expected to significantly affect in-use emissions until
much later in that decade. Second, a NOX reduction standard for
reformulated gasoline would act to reduce emissions from all mobile
sources that use gasoline, whether on-road or off-road, while section
202 or section 213 standards only act to limit emissions from new
engines or vehicles in that specific category of mobile sources. Third,
this fuel control is specifically aimed at areas of the country that
are in nonattainment for ozone, and is limited in time to that part of
the year when ozone is of most concern. Vehicle or engine controls, in
contrast, apply to all new engines or vehicles, wherever they are used,
throughout the year. This fuel control thus allows a more narrow
regulatory solution aimed at the specific geographical areas and time
periods when control is needed. Fourth, the expected increase in
vehicle miles travelled over time leads EPA to believe that this fuel
control is needed to continue to achieve the in-use NOX emission
reductions necessary for many areas of the country to reach attainment
for ozone. Finally, the NOX fuel standard adopted here minimizes
any concern there might be that a fuel control would tend to interfere
in the production process by directing refiners on how to make their
product. The NOX standard is not a fuel recipe, but instead
establishes a performance standard, leaving refiners free to produce
their gasoline in any way that achieves the desired reductions.
EPA is not at this time determining whether additional vehicle or
engine NOX controls should be adopted under section 202 or any
other provision of the Act. Instead, based on all of the above, EPA
believes that a NOX reduction standard for reformulated gasoline
under section 211(c)(1)(A) is an appropriate exercise of discretion,
whether or not the agency imposes additional vehicle or engine NOX
controls in the future.
c. Cost-effectiveness of NOX control in RFG. EPA has evaluated
the cost-effectiveness of NOX control using the same costs that
were used in establishing the standard for VOC control. The results are
summarized in Table VI-2 below. The table indicates that sulfur is the
only fuel parameter that results in significant NOX reductions at
a reasonable cost. Changes in fuel parameters other than sulfur have
only a small effect on NOX emissions at significantly higher
costs, with the possible exception of olefin control (which would
increase VOC at the same time it reduced NOX). A NOX
reduction of approximately 6.8% could be achieved with sulfur control
down to approximately 138 ppm at a reasonable cost, whether compared on
the basis of the cost of the last increment of reduction (5.8% to 6.8%
NOX) or the overall cost incremental to Phase I RFG reductions.
Table VI-2.--Fuel Parameter Control Costs and NOX Reductions\1\
------------------------------------------------------------------------
Incremental
Fuel parameter cost ( Cumulative Incremental Incremental
control cents/gal) reduction cost-eff. to phase I
(percent) ($/ton) ($/ton)\2\
------------------------------------------------------------------------
Phase I:
RVP: 8.0 psi,
Oxygen: 2.1wt
percent,
Benzene: 0.95
percent.........
RVP to 6.7 psi... ........... 0.4
Sulfur to 250 ppm 0.12 2.4 1,300 3,200
Sulfur to 160 ppm 0.56 5.8 3,700 3,500
Sulfur to 138 ppm 0.24 6.8 5,200 3,700
Sulfur to 100 ppm 0.52 8.7 6,200 4,200
Olefins to 8.0
vol percent..... 0.78 10.8 8,000 5,000
Aromatics to 20
vol percent..... 2.01 11.9 40,000 8,200
Oxygen to 2.7 vol
percent......... 0.61 12.5 25,000 8,900
Olefins to 5.0
vol percent..... 2.77 14.1 37,000 12,000
E300 to 88
percent......... 0.35 14.1 (-) 13,000
E300 to 91
percent......... 2.01 14.2 820,000 16,000
E200 to 44
percent......... 0.38 13.9 (-) 17,000
E200 to 47
percent......... 1.32 13.7 (-) 19,000
E200 to 50
percent......... 2.97 13.5 (-) 24,000
------------------------------------------------------------------------
\1\Based on costs and emissions reductions for VOC control region 2
(northern areas). Assumes all costs allocated to NO