[Federal Register Volume 85, Number 13 (Tuesday, January 21, 2020)]
[Proposed Rules]
[Pages 3306-3330]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-00542]
[[Page 3306]]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Parts 86 and 1036
[EPA-HQ-OAR-2019-0055; FRL-10004-16-OAR]
RIN 2060-AU41
Control of Air Pollution From New Motor Vehicles: Heavy-Duty
Engine Standards
AGENCY: Environmental Protection Agency (EPA).
ACTION: Advanced notice of proposed rulemaking.
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SUMMARY: The Environmental Protection Agency (EPA) is soliciting pre-
proposal comments on a rulemaking effort known as the Cleaner Trucks
Initiative (CTI). This advance notice describes EPA's plans for a new
rulemaking that would establish new emission standards for oxides of
nitrogen (NOX) and other pollutants for highway heavy-duty
engines. It also describes opportunities to streamline and improve
certification procedures to reduce costs for engine manufacturers. The
EPA is seeking input on this effort from the public, including all
interested stakeholders, to inform the development of a subsequent
notice of proposed rulemaking.
DATES: Comments must be received on or before February 20, 2020.
ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-
OAR-2019-0055, at http://www.regulations.gov. Follow the online
instructions for submitting comments. Once submitted, comments cannot
be edited or removed from Regulations.gov. The EPA may publish any
comment received to its public docket. Do not submit electronically any
information you consider to be Confidential Business Information (CBI)
or other information whose disclosure is restricted by statute.
Multimedia submissions (audio, video, etc.) must be accompanied by a
written comment. The written comment is considered the official comment
and should include discussion of all points you wish to make. The EPA
will generally not consider comments or comment contents located
outside of the primary submission (i.e., on the web, cloud, or other
file sharing system). For additional submission methods, the full EPA
public comment policy, information about CBI or multimedia submissions,
and general guidance on making effective comments, please visit http://www2.epa.gov/dockets/commenting-epa-dockets.
Public Participation: Submit your comments, identified by Docket ID
No. EPA-HQ-OAR-2019-0055, at http://www.regulations.gov. Follow the
online instructions for submitting comments. Once submitted, comments
cannot be edited or removed from Regulations.gov. The EPA may publish
any comment received to its public docket. Do not submit electronically
any information you consider to be Confidential Business Information
(CBI) or other information whose disclosure is restricted by statute.
Multimedia submissions (audio, video, etc.) must be accompanied by a
written comment. The written comment is considered the official comment
and should include discussion of all points you wish to make. EPA will
generally not consider comments or comment contents located outside of
the primary submission (i.e., on the web, cloud, or other file sharing
system). For additional submission methods, the full EPA public comment
policy, information about CBI or multimedia submissions, and general
guidance on making effective comments, please visit https://www.epa.gov/dockets/commenting-epa-dockets.
Docket. EPA has established a docket for this action under Docket
ID No. EPA-HQ-OAR-2019-0055. All documents in the docket are listed on
the www.regulations.gov website. Although listed in the index, some
information is not publicly available, e.g., CBI or other information
whose disclosure is restricted by statute. Certain other material, such
as copyrighted material, is not placed on the internet and will be
publicly available only in hard copy form. Publicly available docket
materials are available either electronically in www.regulations.gov or
in hard copy at Air and Radiation Docket and Information Center, EPA
Docket Center, EPA/DC, EPA WJC West Building, 1301 Constitution Ave.
NW, Room 3334, Washington, DC. The Public Reading Room is open from
8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal
holidays. The telephone number for the Public Reading Room is (202)
566-1744, and the telephone number for the Air Docket is (202) 566-
1742.
FOR FURTHER INFORMATION CONTACT: Brian Nelson, Office of Transportation
and Air Quality, Assessment and Standards Division, Environmental
Protection Agency, 2000 Traverwood Drive, Ann Arbor, MI 48105;
telephone number: (734) 214-4278; email address: [email protected].
SUPPLEMENTARY INFORMATION:
Table of Contents
I. Introduction
II. Background
A. History of Emission Standards for Heavy-Duty Engines
B. NOX Emissions From Current Heavy-Duty Engines
1. Diesel Engines
2. Gasoline Engines
C. Existing Heavy-Duty Compliance Cost Elements
D. The Need for Additional NOX Control
E. California Heavy-Duty Highway Low NOX Program
Development
III. Potential Solutions and Program Elements
A. Emission Control Technologies
1. Diesel Engine Technologies Under Consideration
2. Gasoline Engine Technologies Under Consideration
3. Emission Monitoring Technologies
4. Hybrid, Battery-Electric, and Fuel Cell Vehicles
5. Alternative Fuels
B. Standards and Test Cycles
1. Emission Standards for RMC and FTP Cycles
2. New Emission Test Cycles and Standards
C. In-Use Emission Standards
D. Extended Regulatory Useful Life
E. Ensuring Long-Term In-Use Emissions Performance
1. Lengthened Emissions Warranty
2. Tamper-Resistant Electronic Controls
3. Serviceability Improvements
4. Emission Controls Education and Incentives
5. Improving Engine Rebuilding Practices
F. Certification and Compliance Streamlining
1. Certification of Carry-Over Engines
2. Modernizing of Heavy-Duty Engine Regulations
3. Heavy-Duty In-Use Testing Program
4. Durability Testing
G. Incentives for Early Emission Reductions
IV. Next Steps
V. Statutory and Executive Order Reviews
I. Introduction
On November 13, 2018, EPA announced plans to undertake a new
rulemaking--the Cleaner Trucks Initiative (CTI)--to update standards
for oxides of nitrogen (NOX) emissions from highway heavy-
duty vehicles and engines.\1\ Although NOX emissions in the
U.S. have dropped by more than 40 percent over the past decade, we
project that heavy-duty vehicles continue to be one of the largest
contributors to the mobile source NOX inventory in 2028.\2\
[[Page 3307]]
Reducing NOX emissions from highway heavy-duty trucks and
buses is thus an important component of improving air quality
nationwide and reducing public health and welfare effects associated
with these pollutants, especially for vulnerable populations and
lifestages, and in highly-impacted regions.
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\1\ EPA's regulations generally classify vehicles with Gross
Vehicle Weight Ratings (GVWRs) above 8,500 pounds (i.e., Class 2b
and above) as heavy-duty vehicles, including large pick-up trucks
and vans, a variety of ``work trucks'' designed for vocational
applications, and combination tractor-trailers.
\2\ U.S. Environmental Protection Agency. ``Air Emissions
Modeling: 2016v1 Platform.'' Available online at: https://www.epa.gov/air-emissions-modeling/2016v1-platform.
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Section 202(a)(1) of the Clean Air Act (the Act) requires the EPA
to set emission standards for air pollutants, including oxides of
nitrogen (NOX), from new motor vehicles or new motor vehicle
engines, which the Administrator has found cause air pollution that may
endanger public health or welfare. Under section 202(a)(3)(A) of the
Act, NOX (and certain other) emission standards for heavy-
duty vehicles and engines are to ``reflect the greatest degree of
emission reduction achievable through the application of technology
which the Administrator determines will be available for the model year
to which such standards apply, giving appropriate consideration to
cost, energy, and safety factors associated with the application of
such technology.'' Section 202(a)(3)(C) requires that standards apply
for no less than 3 model years and apply no earlier than 4 years after
promulgation.
Given the continued contribution of heavy-duty trucks to the
NOX inventory, more than 20 organizations, including state
and local air agencies from across the country, petitioned EPA in the
summer of 2016 to develop more stringent NOX emission
standards for on-road heavy-duty engines.\3\ Among the reasons stated
by the petitioners for EPA rulemaking was the need for NOX
emission reductions to reduce adverse health and welfare impacts and to
help areas attain the National Ambient Air Quality Standards (NAAQS).
EPA subsequently met with a wide range of stakeholders in listening
sessions, during which certain themes were consistent across the range
of stakeholders.\4\ For example, it became clear that there is broad
support for federal action in collaboration with the California Air
Resources Board (CARB). So-called ``50-state'' standards enable
technology suppliers and manufacturers to efficiently produce a single
set of reliable and compliant products. There was broad acknowledgement
of the value of aligning implementation of new NOX standards
with existing milestones for greenhouse gas (GHG) standards under the
Heavy-Duty Phase 2 GHG and fuel efficiency program (``Phase 2'') (81 FR
73478, October 25, 2016). Such alignment would ensure that the GHG and
fuel reductions achieved under Phase 2 are maintained and allow the
regulated industry to implement GHG and NOX technologies
into their products at the same time.\5\
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\3\ Brakora, Jessica. ``Petitions to EPA for Revised
NOX Standards for Heavy-Duty Engines'' Memorandum to
Docket EPA-HQ-OAR-2019-0055. December 4, 2019.
\4\ Stakeholders included: Emissions control technology
suppliers; engine and vehicle manufacturers; a labor union that
represents heavy-duty engine, parts, and vehicle manufacturing
workers; a heavy-duty trucking fleet trade association; an owner-
operator driver association; a truck dealers trade association;
environmental, non-governmental organizations; states and regional
air quality districts; tribal interests; California Air Resources
Board (CARB); and the petitioners.
\5\ The major implementation milestones for the Heavy-duty Phase
2 engine and vehicle standards are in model years 2021, 2024, and
2027.
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EPA responded to the petition on December 20, 2016, noting that an
opportunity exists to develop a new, harmonized national NOX
reduction strategy for heavy-duty highway engines.\3\ EPA emphasized
the importance of scientific and technological information when
determining the appropriate level and form of a future low
NOX standard and highlighted the following potential
components of the action:
Lower NOX emission standards
Improvements to test procedures and test cycles to ensure
emission reductions occur in the real world, not only over the
currently applicable certification test cycles
Updated certification and in-use testing protocols
Longer periods of mandatory emissions-related component
warranties
Consideration of longer regulatory useful life, reflecting
actual in-use activity
Consideration of rebuilding \6\
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\6\ As used here, the term ``rebuilding'' generally includes
practices known commercially as ``remanufacturing''. Under 40 CFR
part 1068, rebuilding refers to practices that fall short of
producing a ``new'' engine.
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Incentives to encourage the transition to current- and next-
generation cleaner technologies as soon as possible
Since then, EPA has assembled a team to gather scientific and
technical data needed to inform our proposal. We intend the CTI to be a
holistic rethinking of emission standards and compliance. Within this
broad goal, we will be looking to the following high-level principles
to inform our approach to this rulemaking:
Our goal should be to reduce in-use emissions under a broad
range of operating conditions \7\
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\7\ We address this goal in the context of National Ambient Air
Quality Standards (NAAQS) nonattainment in Section II.D.
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We should consider and enable effective technological
solutions while carefully considering the cost impacts
Our compliance and enforcement provisions should be fair and
effective
Our regulations should incentivize early compliance and
innovation
We should ensure a coordinated 50-state program
We should actively engage with interested stakeholders
While these principles have been reflected in previous heavy-duty
rulemakings, we nevertheless believe it is helpful to reemphasize them
here as a reminder to both the agency and commenters. We welcome
comment on these principles, as well as other key principles on which
this rule should be based.
It is important to emphasize that this discussion represents EPA's
early views and considerations on possible CTI elements. We request
comment on all aspects of this advance notice. We plan to consider what
we learn from the comments as we develop a Notice of Proposed
Rulemaking (NPRM). Additional information can be found in the docket
for this rulemaking.
II. Background
A. History of Emission Standards for Heavy-Duty Engines
EPA began regulating emissions from heavy-duty vehicles and engines
in the 1970s.8 9 EPA created 40 CFR part 86 in 1976 to
reorganize emission standards and certification requirements for light-
duty and heavy-duty highway vehicles and engines. In 1985, EPA adopted
new standards for heavy-duty highway engines, codifying the standards
in 40
[[Page 3308]]
CFR part 86, subpart A. Since then, EPA has adopted several rules to
set new and more stringent criteria pollutant standards for highway
heavy-duty engine and vehicle emission control programs and to add or
revise certification procedures.\10\
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\8\ EPA's regulations address heavy-duty engines and vehicles
separately from light-duty vehicles. Vehicles with GVWR above 8,500
pounds (Class 2b and above) are classified as heavy-duty. For
criteria pollutants such as NOX, EPA generally applies
the standards to the engines rather than the entire vehicles.
However, for complete heavy-duty vehicles below 14,000 pounds GVWR,
EPA applies standards to the whole vehicle rather than the engine;
this is referred to as chassis-certification and is very similar to
certification of light-duty vehicles.
\9\ Emission standards for heavy-duty highway engines were first
adopted by the Department of Health, Education, and Welfare in the
1960s. These standards and the corresponding certification and
testing procedures were codified at 45 CFR part 1201. In 1972,
shortly after EPA was created as a federal agency, EPA published new
standards and updated procedures while migrating the regulations to
40 CFR part 85 as part of the effort to consolidate all the EPA
regulations in a single location.
\10\ U.S. Environmental Protection Agency. ``EPA Emission
Standards for Heavy-Duty Highway Engines and Vehicles,'' Available
online: https://www.epa.gov/emission-standards-reference-guide/epa-emission-standards-heavy-duty-highway-engines-and-vehicles. (last
accessed December 4, 2019)
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In the 1990s, EPA adopted increasingly stringent NOX,
hydrocarbon, and particulate matter (PM) standards. In 1997 EPA
finalized standards for heavy-duty highway diesels (62 FR 54693,
October 21, 1997), effective with the 2004 model year, including a
combined non-methane hydrocarbon (NMHC) and NOX standard
that represented a reduction of NOX emissions by 50 percent.
These NOX reductions also resulted in significant reductions
in secondary nitrate particulate matter.
In early 2001, EPA finalized the 2007 Heavy-Duty Engine and Vehicle
Rule (66 FR 5002, January 18, 2001) to continue addressing
NOX and PM emissions from both diesel and gasoline-fueled
highway heavy-duty engines. This rule established a comprehensive
national program that regulated a heavy-duty engine and its fuel as a
single system, with emission standards taking effect beginning with
model year 2007 and fully phasing in by model year 2010. These
standards projected the use of high-efficiency catalytic exhaust
emission control devices. To ensure proper functioning of these
technologies, which could be damaged by sulfur, EPA also mandated
reducing the level of sulfur in highway diesel fuel by 97 percent by
mid-2006. These actions resulted in engines that emit PM and
NOX emissions at levels 90 percent and 95 percent below
emission levels from then-current highway heavy-duty engines,
respectively. The PM standard for new highway heavy-duty engines was
set at 0.01 grams per brake-horsepower-hour (g/hp-hr) by 2007 model
year and the NOX and NMHC standards of 0.20 g/hp-hr and 0.14
g/hp-hr, respectively, were set to phase in between 2007 and 2010. In
finalizing this rule, EPA estimated that the emission reductions would
achieve significant health and environmental impacts, and total
monetized PM2.5- and ozone-related benefits of the program
would exceed $70 billion, versus program costs of $4 billion (1999$).
In 2009, as advanced emissions control systems were being
introduced to meet the 2007/2010 standards, EPA promulgated a final
rule to require that these advanced emissions control systems be
monitored for malfunctions via an onboard diagnostic (OBD) system (74
FR 8310, February 24, 2009). The rule, which has been fully phased in,
required engine manufacturers to install OBD systems that monitor the
functioning of emission control components on new engines and alert the
vehicle operator to any detected need for emission related repair. It
also required that manufacturers make available to the service and
repair industry information necessary to perform repair and maintenance
service on OBD systems and other emission related engine components.
Also in 2009, EPA and Department of Transportation's National
Highway Traffic Safety Administration (NHTSA) began working on a joint
regulatory program to reduce greenhouse gas emissions (GHGs) and fuel
consumption from heavy-duty vehicles and engines.\11\ By utilizing
regulatory approaches recommended by the National Academy of Sciences,
the first phase (``Phase 1'') of the GHG and fuel efficiency program
was finalized in 2011 (76 FR 57106, September 15, 2011).\12\ The Phase
1 program, spanning implementation from model years 2014 to 2018,
included separate standards for highway heavy-duty vehicles and heavy-
duty engines. The program offered flexibility allowing manufacturers to
attain these standards through a mix of technologies, and the use of
various emissions credit averaging and banking programs.
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\11\ Greenhouse gas emissions from heavy-duty engines are
primarily carbon dioxide (CO2), but also include methane
(CH4) and nitrous oxide (N2O). Because
CO2 is formed from the combustion of fuel, it is directly
related to fuel consumption. References in this notice to increasing
or decreasing CO2 can be taken to be qualitative
references to fuel consumption as well.
\12\ The National Academies' Committee to Assess Fuel Economy
Technologies for Medium- and Heavy-Duty Vehicles; National Research
Council; Transportation Research Board. ``Technologies and
Approaches to Reducing the Fuel Consumption of Medium- and Heavy-
Duty Vehicles.'' 2010. Available online: https://www.nap.edu/catalog/12845/technologies-and-approaches-to-reducing-the-fuel-consumption-of-medium-and-heavy-duty-vehicles.
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In 2016, EPA and NHTSA finalized the Heavy-Duty Phase 2 GHG and
fuel efficiency program (81 FR 73478, October 25, 2016). Phase 2
includes technology-advancing performance-based standards that will
phase in over the long-term, with initial standards for most vehicles
and engines commencing in model year 2021, increasing in stringency in
model year 2024, and culminating in model year 2027 standards. Phase 2
builds on and advances the Phase 1 program and includes standards based
not only on currently available technologies but also on technologies
under development or not yet widely deployed. To ensure adequate time
for technology development, Phase 2 provided up to 10 years lead time
to allow for the development and phase in of these controls, further
encouraging innovation and providing transitional flexibility.
B. NOX Emissions From Current Heavy-Duty Engines
For heavy-duty vehicles, EPA generally applies non-GHG emission
standards to engines rather than the entire vehicles. However, most of
the Class 2b and 3 pickup trucks and vans (vehicles with a Gross
Vehicle Weight Rating (GVWR) between 8,500 and 14,000 pounds) are
certified as complete heavy-duty vehicles; this is referred to as
chassis-certification and is very similar to certification of light-
duty vehicles. In fact, these chassis-certified vehicles are covered by
standards in EPA's Tier 3 program, which primarily covers light-duty
vehicles (79 FR 23414, April 28, 2014; 80 FR 0978, February 19, 2015).
We do not intend to propose changes to the standards or test procedures
for chassis-certified heavy-duty vehicles. Instead, the CTI will focus
on engine-certified products.
1. Diesel Engines
As outlined in the previous section, the current heavy-duty engine
emission standards reduced PM and NOX tailpipe emissions by
over 90 percent for emissions measured using the specified test
procedures, but their impact on in-use emissions during real-world
operation is less clear. The diesel particulate filters (DPFs) that
manufacturers are using to control PM emissions have reduced PM
emissions to very low levels during virtually all types of operation.
However, while the selective catalytic reduction (SCR) systems used to
control NOX emissions can achieve very low levels during
most operation, there remain operating modes where the SCR systems are
much less effective.13 14 For example, NOX
emissions can be significantly higher during engine warm-up, idling,
and certain other types of operation that result in low load on the
engine or
[[Page 3309]]
transitioning from low to high loads. Moreover, deterioration of
emission controls in-use, along with tampering and mal-maintenance, can
result in additional NOX emissions. In addition to tailpipe
emissions, diesel engines with unsealed crankcases generally emit a
small amount of exhaust-related emissions when venting blowby gases
from the crankcase. Each of these sources of higher emissions presents
an opportunity for additional reduction and we introduce potential
solutions in Section III.A.1.
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\13\ Hamady, Fakhri, Duncan, Alan. ``A Comprehensive Study of
Manufacturers In-Use Testing Data Collected from Heavy-Duty Diesel
Engines Using Portable Emissions Measurement System (PEMS)''. 29th
CRC Real World Emissions Workshop, March 10-13, 2019.
\14\ Sandhu, Gurdas, et al. ``Identifying Areas of High
NOX Operation in Heavy-Duty Vehicles''. 28th CRC Real-
World Emissions Workshop, March 18-21, 2018.
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2. Gasoline Engines
Heavy-duty gasoline engines rely on three-way catalysts (TWC) to
simultaneously reduce HC, CO, and NOX. This is the same type
of technology used for passenger cars and light-duty trucks. Once the
TWC has reached its light-off temperature,\15\ it can achieve very low
emission levels if the fuel-air ratio of the engine is properly
controlled and calibrated. However, the application of TWC technology
to heavy-duty gasoline engines and vehicles is less optimized for
emissions than for light-duty. Accordingly, from start-up until the
system reaches its light-off temperature, emissions are elevated.
Technologies and strategies that accelerate TWC light-off could reduce
start-up emissions from heavy-duty gasoline engines.
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\15\ The ``light-off'' temperature is nominally the temperature
at which a catalyst becomes hot enough to begin functioning
effectively.
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Additionally, the maximum temperature thresholds that today's
heavy-duty TWCs are designed to tolerate could be exceeded by gasoline
engine exhaust temperatures during high-load stoichiometric operation.
Consequently, heavy-duty manufacturers often implement enrichment-based
strategies for engine and catalyst protection at high load. Enrichment,
which is accomplished by injecting additional fuel and temporarily
shifting to a rich fuel-air ratio, has long been used in gasoline
engine operation to cool excessive exhaust gas temperatures to protect
vital engine and exhaust components such as exhaust valves, manifolds,
and catalysts. However, enrichment also results in higher emissions,
including HC, CO, and PM. Technologies or strategies that expand the
TWC operating temperature range could reduce the need for enrichment
and further reduce emissions from heavy-duty gasoline engines.
C. Existing Heavy-Duty Compliance Cost Elements
Manufacturers have incurred significant costs over the years to
reduce emissions from heavy-duty engines and costs will be an important
aspect of the CTI as we consider new standards and other compliance
provisions. This Section C is an overview of current types of costs,
which is intended to provide context for later discussions throughout
this ANPR.
The majority of the costs to comply with emission standards are
directly related to the emission control technologies used by
manufacturers. Technology costs include both the pre-production costs
for activities such as research and development (R&D) and the costs to
produce and warranty emission control components. Vehicle owners and
operators may also incur costs related to compliance with emission
standards if the requirements impact operating costs. EPA will evaluate
technology and operating costs as part of the technological feasibility
and cost analysis for new standards in the NPRM.
The remaining compliance costs for manufacturers are primarily
associated with testing, reporting and recordkeeping to demonstrate and
assure compliance. As a part of the CTI, we intend to evaluate these
costs and identify opportunities to lower them by streamlining our
compliance processes. (See Section III.F.) These non-technological
costs occur in three broad categories:
1. Pre-certification emission testing.
2. Certification reporting.
3. Post-certification testing, reporting, and recordkeeping.
The Clean Air Act requires manufacturers wishing to sell heavy-duty
engines in the U.S. to obtain emission Certificates of Conformity each
year. To do so, manufacturers must submit an application for
certification to EPA for each family of engines.\16\ As specified in 40
CFR 86.007-21 and 1036.205, manufacturers must include a significant
amount of information and emission test results to demonstrate to EPA
that their engines will meet the applicable emission standards and
related requirements.
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\16\ An engine family is a group of engines with similar
emission characteristics as defined in 40 CFR 86.001-24 and related
sections.
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Although most compliance costs occur before and during
certification, manufacturers incur additional costs after
certification. Manufacturers may be required to test a sample of
production engines during the model year, as well as vehicles in actual
use (see Sections III.B and III.C). Manufacturers must also submit end-
of-year production reports. Finally, manufacturers must maintain
compliance records for up to eight years.
D. The Need for Additional NOX Control
As noted in the Introduction, emissions of criteria pollutants have
been declining over time due to federal, state, and local regulations
and voluntary programs.\17\ However, there continues to be a need for
additional NOX emission reductions in spite of the
significant technological progress made to-date.\18\ NOX is
a criteria pollutant, as well as a precursor to ozone and
PM2.5, and as such NOX emissions contribute to
ambient pollution that adversely affects human health (including
vulnerable populations and lifestages, which are relevant to both
children's health and environmental justice issues) and the
environment. EPA has set primary and secondary NAAQS for each of these
pollutants designed to protect public health and welfare. As of
September 30, 2019, more than 128 million people lived in counties
designated nonattainment for the ozone or PM2.5 NAAQS, and
additional people live in areas with a risk of exceeding those NAAQS in
the future.\19\ Reductions in NOX emissions will help areas
attain and maintain the ozone and PM2.5 NAAQS and help
prevent future nonattainment. Reducing NOX emissions will
result in improved health outcomes attributable to lower ozone and
particulate matter concentrations in communities across the United
States.
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\17\ EPA publishes an annual air trends report in the form of an
interactive web application (https://gispub.epa.gov/air/trendsreport/2019/).
\18\ Davidson, K., Zawacki, M. Memorandum to Docket EPA-HQ-OAR-
2019-0055. ``Health and Environmental Effects of NOX,
Ozone and PM'' October 22, 2019.
\19\ EPA publishes information on nonattainment areas on its
green book website (https://www3.epa.gov/airquality/greenbook/popexp.html). This data comes from the Summary Nonattainment Area
Population Exposure Report, current as of September 30, 2019.
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Human health impacts of concern are associated with exposures to
NOX, ozone, and PM2.5.20 21 22 23
Short-term
[[Page 3310]]
exposures to NO2 (an oxide of nitrogen) can aggravate
respiratory diseases, particularly asthma, leading to respiratory
symptoms, hospital admissions and emergency department visits. Long-
term exposures to NO2 have been shown to contribute to
asthma development and may also increase susceptibility to respiratory
infections. Ozone exposure reduces lung function and causes respiratory
symptoms, such as coughing and shortness of breath. Ozone exposure also
aggravates asthma and lung diseases such as emphysema, leading to
increased medication use, hospital admissions, and emergency department
visits. Exposures to PM2.5 can cause harmful effects on the
cardiovascular system, including heart attacks and strokes. These
effects can result in emergency department visits, hospitalizations
and, in some cases, premature death. PM exposures are also linked to
harmful respiratory effects, including asthma attacks. Moreover, many
groups are at greater risk than healthy people from these pollutants,
including: People with heart or lung disease, outdoor workers and the
lifestages of older adults and children. Environmental impacts of
concern are associated with these pollutants and include light
extinction, decreased tree growth, foliar injury, and acidification and
eutrophication of aquatic and terrestrial systems.
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\20\ U.S. EPA. Integrated Science Assessment (ISA) For Oxides Of
Nitrogen--Health Criteria (Final Report, 2016). U.S. Environmental
Protection Agency, Washington, DC, EPA/600/R-15/068, 2016.
\21\ U.S. EPA. Integrated Science Assessment (ISA) of Ozone and
Related Photochemical Oxidants (Final Report, Feb 2013). U.S.
Environmental Protection Agency, Washington, DC, EPA/600/R-10/076F,
2013.
\22\ U.S. EPA. Integrated Science Assessment (ISA) For
Particulate Matter (Final Report, Dec 2009). U.S. Environmental
Protection Agency, Washington, DC, EPA/600/R-08/139F, 2009.
\23\ There is an ongoing review of the PM NAAQS, EPA intends to
finalize the Integrated Science Assessment in late 2019 (https://www.epa.gov/naaqs/particulate-matter-pm-standards-integrated-science-assessments-current-review). There is an ongoing review of
the ozone NAAQS, EPA intends to finalize the Integrated Science
Assessment in early 2020 (https://www.epa.gov/naaqs/ozone-o3-standards-integrated-science-assessments-current-review).
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Heavy-duty vehicles continue to be a significant source of
NOX emissions now and into the future. While the mobile
source NOX inventory is projected to decrease over time,
recent emissions modeling indicates that heavy-duty vehicles will
continue to be one of the largest contributors to mobile source
NOX emissions nationwide in 2028.\24\ Many state and local
agencies have asked the EPA to further reduce NOX emissions,
specifically from heavy-duty engines; the importance of reducing heavy-
duty NOX emissions has been highlighted in the June 3, 2016
petition (see Section I) that was submitted to EPA and in other
correspondence from stakeholders.25 26 27 28 Pollution
formed from NOX emissions can occur and be transported far
from the source of the emissions themselves, and heavy-duty trucks can
travel regionally and nationally. Air quality modeling indicates that
heavy-duty diesel NOX emissions are contributing to
substantial concentrations of ozone and PM2.5 across the
U.S. For example, heavy-duty diesel engine NOX emissions are
important contributors to modeled ozone and PM2.5
concentrations across the U.S. in 2025.\29\ Another recent air quality
modeling analysis indicates that transport of ozone produced in
NOX-sensitive environments impacts ozone concentrations in
downwind areas, often several states away.\30\ A national program to
reduce NOX emissions from heavy-duty engines would allow all
states to benefit from the emission reductions and maximize the benefit
for downwind states.
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\24\ U.S. Environmental Protection Agency. ``Air Emissions
Modeling: 2016v1 Platform''. Available online at: https://www.epa.gov/air-emissions-modeling/2016v1-platform.
\25\ Ozone Transport Commission. Correspondence Regarding EPA's
Tampering Policy. August 28, 2019. Available online: https://otcair.org/upload/Documents/Correspondence/EPA%20Tampering%20Policy%20Letter.pdf.
\26\ National Association of Clean Air Agencies letter to U.S.
EPA, June 21, 2018.
\27\ South Coast Air Quality Management District. ``South Coast
Air Quality Management District's Support for Petitions for Further
NOX Reductions from Heavy-Duty Trucks and Locomotives''
Letter to U.S. EPA, June 15, 2018.
\28\ NESCAUM. ``The Northeast's Need for NOX
Reductions.'' Presented at SAE Government Industry Meeting, April
2019.
\29\ Zawacki et al., 2018. Mobile source contributions to
ambient ozone and particulate matter in 2025. Vol 188, pg 129-141.
Available online: https://doi.org/10.1016/j.atmosenv.2018.04.057.
\30\ U.S. Environmental Protection Agency: Air Quality Modeling
Technical Support Document for the Final Cross State Air Pollution
Rule Update. August 2016. Available online: https://www.epa.gov/sites/production/files/2017-05/documents/aq_modeling_tsd_final_csapr_update.pdf.
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E. California Heavy-Duty Highway Low NOX Program Development
In this section, we present a summary of the current efforts by the
state of California to establish new, lower emission standards for
highway heavy-duty engines and vehicles. For the past several decades,
EPA and the California Air Resources Board (CARB) have worked together
to reduce air pollutants from highway heavy-duty engines and vehicles
by establishing harmonized emission standards for new engines and
vehicles. For much of this time period, EPA has taken the lead in
establishing emission standards through notice and comment rulemaking,
after which CARB would adopt the same standards and test procedures.
For example, EPA adopted the current heavy-duty engine NOX
and PM standards in a 2001 final rule, and CARB subsequently adopted
the same emission standards. EPA and CARB often cooperate during the
implementation of highway heavy-duty standards. Thus, for many years
the regulated industry has been able to design a single product line of
engines and vehicles which can be certified to both EPA and CARB
emission standards (which have been the same) and sold in all 50
states.
Given the significant ozone and PM air quality challenges in the
state of California, CARB has taken a number of steps to establish
standards beyond the current EPA requirements to further reduce
NOX emissions from heavy-duty vehicles and engines in their
state. CARB's optional (voluntary) low NOX program, started
in 2013, was created to encourage heavy-duty engine manufacturers to
introduce technologies that emit NOX at levels below the
current US 2010 standards. Under this optional program, manufacturers
can certify their engines to one of three levels of stringency that are
50, 75, and 90 percent below the existing US 2010 standards, the lowest
optional standard being 0.02 grams NOX per horsepower-hour
(g/hp-h), which is a 90 percent reduction from today's federal
standards.\31\ To date, only natural gas and liquefied petroleum gas
engines have been certified to the optional standards.
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\31\ California Code of Regulations, Title 13, section 1956.8.
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In May 2016, CARB published its Mobile Source Strategy outlining
their approach to reduce in-state emissions from mobile sources and
meet their air quality targets.\32\ In November 2016, CARB held its
first Public Workshop on their plans to update their heavy-duty engine
and vehicle programs.\33\ CARB's 2016 Workshop kicked off a technology
demonstration program (the CARB ``Low NOX Demonstration
Program''), and announced plans to update emission standards,
laboratory-based and in-use test procedures, emissions warranty,
durability demonstration requirements, and regulatory useful life
provisions. The initiatives introduced in their 2016 Workshop have
since become components of CARB's Heavy-Duty ``Omnibus'' Low
NOX Rulemaking.
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\32\ California Air Resources Board. ``Mobile Source Strategy''.
May 2016. Available online: https://ww3.arb.ca.gov/planning/sip/2016sip/2016mobsrc.pdf.
\33\ California Air Resources Board. ``Heavy-Duty Low
NOX: Meetings & Workshops''. Available online: https://ww2.arb.ca.gov/our-work/programs/heavy-duty-low-nox/heavy-duty-low-nox-meetings-workshops.
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CARB's goal for its Low NOX Demonstration Program was to
investigate the feasibility of reducing NOX emissions to
levels significantly below today's US 2010 standards. Southwest
Research Institute (SwRI)
[[Page 3311]]
was contracted to perform the work, which was split into three
``Stages''.\34\ In Stage 1, SwRI demonstrated an engine technology
package capable of achieving a 90 percent NOX emissions
reduction on today's regulatory test cycles.\35\ In Stage 1b, SwRI
applied an accelerated aging process to age the Stage 1 aftertreatment
components to evaluate their performance. SwRI developed and evaluated
a new low load-focused engine test cycle for Stage 2. In Stage 3, SwRI
is evaluating a new engine platform and different technology package to
ensure emission performance. EPA has been closely following CARB's Low
NOX Demonstration Program as a member of the Low
NOX Advisory Group for the technology development work. The
CARB Low NOX Advisory Group, which includes representatives
from heavy-duty engine and aftertreatment industries, as well as from
federal, state, and local governmental agencies, receives updates from
SwRI on a bi-weekly basis.\36\
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\34\ Southwest Research Institute. ``Update on Heavy-Duty Low
NOX Demonstration Programs at SwRI''. September 26, 2019.
Available online: https://ww3.arb.ca.gov/msprog/hdlownox/files/workgroup_20190926/guest/swri_hd_low_nox_demo_programs.pdf.
\35\ Southwest Research Institute. ``Evaluating Technologies and
Methods to Lower Nitrogen Oxide Emissions from Heavy-Duty Vehicles:
Final Report''. April 2017. Available online: https://ww3.arb.ca.gov/research/apr/past/13-312.pdf.
\36\ California Air Resources Board. ``Evaluating Technologies
and Methods to Lower Nitrogen Oxide Emissions from Heavy-Duty
Vehicles''. May 10, 2017. Available online: https://ww3.arb.ca.gov/research/veh-emissions/low-nox/low-nox.htm.
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CARB has published several updates related to their Omnibus
Rulemaking. In June 2018, CARB approved their ``Step 1'' update to
California's emission control system warranty regulations.\37\ Starting
in model year (MY) 2022, the existing 100,000-mile warranty for all
diesel engines would lengthen to 110,000 miles for engines certified as
light heavy-duty, 150,000 miles for medium heavy-duty engines, and
350,000 for heavy heavy-duty engines. In November 2018, CARB approved
revisions to the onboard diagnostics (OBD) requirements that include
implementation of real emissions assessment logging (REAL) for heavy-
duty engines and other vehicles.\38\ In April 2019, CARB published a
``Staff White Paper'' to present their staff's assessment of the
technologies they believed were feasible for medium and heavy heavy-
duty diesel engines in the 2022-2026 timeframe.\39\
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\37\ California Air Resources Board. ``HD Warranty 2018'' June
28, 2018. Available online: https://ww2.arb.ca.gov/rulemaking/2018/hd-warranty-2018.
\38\ California Air Resources Board. ``Heavy-Duty OBD
Regulations and Rulemaking''. Available online: https://ww2.arb.ca.gov/resources/documents/heavy-duty-obd-regulations-and-rulemaking.
\39\ California Air Resources Board. ``California Air Resources
Board Staff Current Assessment of the Technical Feasibility of Lower
NOX Standards and Associated Test Procedures for 2022 and
Subsequent Model Year Medium-Duty and Heavy-Duty Diesel Engines''.
April 18, 2019. Available online: https://ww3.arb.ca.gov/msprog/hdlownox/white_paper_04182019a.pdf.
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CARB staff are expected to present the Heavy-Duty NOX
Omnibus proposal to their governing board for final approval in 2020.
It is expected to include updates to their engine standards,
certification test procedures, and heavy-duty in-use testing program
that would take effect in model year 2024, with additional updates to
warranty, durability, and useful life provisions and further reductions
in standards beginning in model year 2027.
While we are not requesting comment on whether CARB should adopt
these updates, we are requesting comment on the extent to which EPA
should adopt similar provisions, and whether similar EPA requirements
should reflect different stringency or timing. Commenters supporting
EPA requirements that differ from the expected CARB program are
encouraged to address how such differences could be implemented to
maintain a national program to the extent possible. For example, how
important would it be to harmonize test procedures, even if we adopt
different standards? Also, how might standards be aligned if
stringencies are harmonized, but timing differs?
III. Potential Solutions and Program Elements
EPA's current certification and compliance programs for heavy-duty
engines began in the 1970s--a period that predates advanced emission
controls and electronic engine controls. Although we have made
significant modifications to these programs over the years, we believe
it is an appropriate time to reconsider their fundamental structures
and refocus them to reflect twenty-first century technology and
approaches.
As described previously, the CTI can be summarized as a holistic
approach to implementing our Clean Air Act obligations. One of our
high-level principles, discussed in the Introduction, is to consider
and enable effective solutions and give careful consideration to the
cost impacts. Within that principle, we have identified the following
key goals: \40\
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\40\ Our identification of these key components to consider is
informed by section 202(a) of the Clean Air Act which directs EPA to
establish emission standards for heavy-duty engines that ``reflect
the greatest degree of emission reduction achievable through the
application of technology which the Administrator determines will be
available'' and to consider ``cost, energy, and safety factors
associated with the application of such technology.''
Our program should not undermine the industry's plans to meet
the CO2 and fuel consumption requirements of the Heavy-duty
Phase 2 program and should not adversely impact safety
CTI should leverage ``smart'' communications and computing
technology
CTI will provide sufficient lead time and stability for
manufacturers to meet new requirements
CTI should streamline and modernize regulatory requirements
CTI should support improved vehicle reliability
Commenters are encouraged to address these goals. We also welcome
comments on other potential goals that should be considered for the
CTI.
Keeping with our goal of providing appropriate lead time for new
standards and stability of product designs, and also meeting CAA
requirements, we are considering implementation of new standards
beginning in model year 2027, which is also the implementation year for
the final set of Heavy-Duty Phase 2 standards. This would provide four
to six full model years of lead time and would allow manufacturers to
implement a single redesign, aligning the final step of the Phase 2
standards with the potential new CTI requirements.
As part of our early developmental work for this rulemaking, EPA
has identified technologies that we currently believe could be used to
reduce NOX emissions from heavy-duty engines in the 2027
timeframe. Our early feasibility assessments for these technologies are
discussed below along with potential updates to test procedures and
other regulatory provisions.
Although our focus in this rulemaking is primarily on future model
years, we also seek comment on the extent to which the technologies and
solutions could be used by state, local, or tribal governments in
reducing emissions from the existing, pre-CTI heavy-duty fleet. EPA's
Clean Diesel Program, which includes grants and rebates funded under
the Diesel Emissions Reduction Act (DERA), is just one example of a
partnership between EPA and stakeholders that provides incentives for
upgrades and retrofits to the existing fleet of on-road and
[[Page 3312]]
nonroad diesel vehicles and equipment to lower air pollution.\41\
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\41\ U.S. Environmental Protection Agency. ``Clean Diesel and
DERA Funding'' Available online: https://www.epa.gov/cleandiesel
(accessed December 12, 2019).
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A. Emission Control Technologies
This section addresses technologies that, based on our current
understanding, would be available in the 2024 to 2030 timeframe to
reduce emissions and ensure robust in-use compliance.\42\ Although much
of the discussion focuses on the current state of the technology, the
planned NPRM analysis necessarily will be based on our projections of
future technology development and availability in accordance with the
Clean Air Act.
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\42\ Although we are targeting model year 2027 for new
standards, our technology evaluations are considering a broader
timeframe to be more comprehensive.
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The discussions below primarily concern the feasibility and
effectiveness of the technologies. We request comment on each of the
technologies discussed. Commenters are encouraged to address all
aspects of these technologies including: Costs, emission reduction
effectiveness, impact on fuel consumption/CO2 emissions,
market acceptance factors, reliability, and the feasibility of the
technology being available for widespread adoption in the 2027 and
later timeframe. We also welcome comments on other technologies not
discussed here. Finally, to the extent emission reductions will be
limited by the manufacturers' engineering resources, we encourage
commenters to address how we should prioritize or phase-in different
requirements.
1. Diesel Engine Technologies Under Consideration
The following discussion introduces the technologies and emission
reduction strategies we are considering for the CTI, including thermal
management technologies that can be used to better achieve and maintain
adequate catalyst temperatures, and next generation catalyst
configurations and formulations to improve catalyst performance across
a broader range of engine operating conditions. Where possible, we note
the technologies and strategies we are evaluating in our diesel
technology feasibility demonstration program at EPA's National Vehicle
and Fuels Emissions Laboratory. A description of additional
technologies we are following is available in the docket.\43\ From a
regulatory perspective, EPA's evaluation of the effectiveness of
technologies includes their emission reduction potential, as well as
their durability over the engine's regulatory useful life and potential
impact on CO2 emissions.
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\43\ Mikulin, John. ``Opposed-Piston Diesel Engines'' Memorandum
to Docket EPA-HQ-OAR-2019-0055. November 20, 2019.
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The costs associated with the technologies in our demonstration
program will also be considered, along with other relevant factors, in
the overall feasibility analysis presented in the NPRM. Our assessment
of costs is currently underway and will be an important component of
the NPRM. Our current understanding of likely technology costs is based
largely on survey data, catalyst costs published by the International
Council for Clean Transportation (ICCT),\44\ and catalyst volume and
other emission component characteristics that engine manufacturers have
submitted to EPA and claimed to be CBI. We have initiated a cost study
based on a technology teardown approach that will apply the peer-
reviewed methodology previously used for light-duty vehicles.\45\ This
teardown analysis may still be underway during the planned timeline for
the NPRM. We welcome comment including any available data on the cost,
effectiveness, and limitations of the SCR and other emission control
systems considered. We also request comment, including any available
data, regarding the technical feasibility and cost of commercializing
emerging technologies expected to enter the heavy-duty market by model
year 2027.
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\44\ Dallmann, T., Posada, F., Bandivadekar, A. ``Costs of
Emission Reduction Technologies for Diesel Engines Used in Non-Road
Vehicles and Equipment'' International Council on Clean
Transportation. July 11, 2018. Available online: https://theicct.org/sites/default/files/publications/Non_Road_Emission_Control_20180711.pdf.
\45\ Kolwich, G., Steier, A., Kopinski, D., Nelson, B. et al.,
``Teardown-Based Cost Assessment for Use in Setting Greenhouse Gas
Emissions Standards,'' SAE Int. J. Passeng. Cars--Mech. Syst.
5(2):1059-1072, 2012, https://doi.org/10.4271/2012-01-1343.
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Modern diesel engines rely heavily upon catalytic aftertreatment to
meet emission standards--oxidation catalysts reduce hydrocarbons (HC)
and carbon monoxide (CO), DPFs reduce PM, and SCR catalysts reduce
NOX. Current designs typically include the diesel oxidation
catalyst (DOC) function as part of the broader DPF/SCR system.\46\
While DPFs remain effective at controlling PM during all types of
operation,\47\ SCR systems (including the DOC function) are effective
only when the exhaust temperature is sufficiently high. All three types
of aftertreatment have the potential to lose effectiveness if the
catalysts degrade. Potential technological solutions to these issues
are discussed below, with a focus on the SCR system.
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\46\ McDonald, Joseph. ``Diesel Exhaust Emission Control
Systems,'' Memorandum to Docket EPA-HQ-OAR-2019-0055. November 13,
2019.
\47\ PM emissions can increase briefly during active
regeneration of the DPF; however, such events are infrequent.
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SCR works by injecting into the exhaust a urea-water solution,
which decomposes to form gaseous ammonia (NH3).
NH3 is a strong reducing agent that reacts to convert
NOX to N2 and H2O over a range of
catalytic materials. The DOC, located upstream of the SCR, uses a
platinum (Pt) and palladium (Pd) catalyst to oxidize a portion of the
exhaust NO to NO2.\48\ This oxidation facilitates the
``fast'' SCR reaction pathway that improves the SCR's NOX
reduction kinetics when exhaust temperatures are below 250 [deg]C and
is highly-efficient above 250 [deg]C. An ammonia slip catalyst (ASC) is
typically used immediately downstream of the SCR to prevent emissions
of unreacted NH3 into the environment.
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\48\ The DOC also synergistically converts additional NO to
NO2, promoting low-temperature soot oxidation over the
DPF.
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Compression-ignition engine exhaust temperatures are low during
cold starts, sustained idle, or low vehicle speed and light load. This
impacts emissions because urea decomposition to NH3 and
subsequent NOX reduction over the SCR catalyst significantly
decreases at exhaust temperatures of less than 190 [deg]C. Thus,
technologies that accelerate warm-up from a cold start, and maintain
catalyst temperature above 200 [deg]C can help achieve further
NOX reduction from SCR systems under those conditions.
Technologies that improve urea decomposition to NH3 at
temperatures below 200 [deg]C can also be used to reduce NOX
emissions under cold start, light load, and low speed conditions.
Additional discussion of is available in the docket.\49\
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\49\ McDonald, Joseph. ``Diesel Exhaust Emission Control
Systems,'' Memorandum to Docket EPA-HQ-OAR-2019-0055. November 13,
2019.
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i. Advanced Catalyst Formulations
Catalysts continue to evolve as engine manufacturers demand
formulations that are optimized for their specific performance
requirements. Improvements to DOC and DPF washcoat \50\ materials that
increase active surface area and stabilize active materials have
allowed a reduction in content of platinum group metals and a reduction
in DOC size between MY2010 and MY2019. Increased usage of silicon
carbide as DPF substrate material has
[[Page 3313]]
allowed the use of smaller DPF substrates that reduce exhaust
backpressure and improve system packaging onto the vehicle.
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\50\ The wash-coat is a high surface area catalytic coating that
is applied to a noncatalytic substrate. The wash-coat includes the
active catalytic sites.
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Copper (Cu) exchanged zeolites have demonstrated hydrothermal
stability, good low temperature performance, and represent a large
fraction of the transition-metal zeolite SCR catalysts used in heavy-
duty applications since 2010.\51\ Improvements to both the coating
processes and the substrates onto which the zeolites are coated have
improved the low-temperature and high-temperature NOX
conversion, improved selectivity of NOX reduction to
N2 (i.e., reduced selectivity to N2O), and
improved the hydrothermal stability. Improvements in SCR catalyst
coatings over the past decade have included: 52 53 54 55 56
\51\ Lambert, C.K. ``Perspective on SCR NOX control
for diesel vehicles.'' Reaction Chemistry & Engineering, 2019, 4,
969.
\52\ Fan, C., et al. (2018). ``The influence of Si/Al ratio on
the catalytic property and hydrothermal stability of Cu-SSZ-13
catalysts for NH3-SCR.'' Applied Catalysis A: General 550: 256-265.
\53\ Fedyko, J. M. and H.-Y. Chen (2015). Zeolite Catalyst
Containing Metals. U. S. Patent No. US20150078989A1, Johnson Matthey
Public Limited Company, London.
\54\ Cui, Y., et al. (2020). ``Influences of Na+ co-cation on
the structure and performance of Cu/SSZ-13 selective catalytic
reduction catalysts.'' Catalysis Today 339: 233-240.
\55\ Fedyko, J. M. and H.-Y. Chen (2019). Zeolite Catalyst
Coating Containing Metals. U.S. Patent No. US 20190224657A1, Johnson
Matthey Public Limited Company, London, UK.
\56\ Wang, A., et al. (2019). ``NH3-SCR on Cu, Fe and Cu+ Fe
exchanged beta and SSZ-13 catalysts: Hydrothermal aging and
propylene poisoning effects.'' Catalysis Today 320: 91-99.
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Optimization of Silicon/Aluminum (Al) and Cu/Al ratios
Increased Cu content and Cu surface area
Optimization of the relative positioning of Cu\2+\ ions within
the zeolite structure
The introduction of specific co-cations
Co-exchanging of more than one type of metal ion into the
zeolite structure
In the absence of more stringent NOX standards, these
improvements have been realized primarily as reductions in SCR system
volume, reductions in system cost, and improvements in durability since
the initial introduction of metal-exchanged zeolite SCR in MY2010. We
request comment on the extent to which advanced catalyst formulations
can be used to lower emissions further, and whether they would have any
potential impact on CO2 emissions.
ii. Passive Thermal Management
Passive thermal management involves modifying components to
increase and maintain the exhaust gas temperatures without active
management. It is done primarily through insulation of the exhaust
system and/or reducing its thermal mass (so it requires less exhaust
energy to reach the light-off temperature).\57\ Passive thermal
management strategies generally have little to no impact on
CO2 emissions. The use of passive exhaust thermal management
strategies in light-duty gasoline applications has led to significant
improvements in emission performance. Some of these improvements could
be applied to SCR systems used in heavy-duty applications as well.
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\57\ Hamedi, M., Tsolakis, A., and Herreros, J., ``Thermal
Performance of Diesel Aftertreatment: Material and Insulation CFD
Analysis,'' SAE Technical Paper 2014-01-2818, 2014, doi:10.4271/
2014-01-2818.
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Reducing the mass of the exhaust system and insulating between the
turbocharger outlet and the inlet of the SCR system would reduce the
amount of thermal energy lost through the walls. Moving the SCR
catalyst nearer to the turbocharger outlet effectively reduces the
available mass prior to the SCR inlet, minimizing heat loss and
reducing the amount of energy needed to warm components up to normal
operating temperatures. Using a smaller sized initial SCR with a lower
density substrate reduces its mass and reduces catalyst warmup time.
Dual-walled manifolds and exhaust pipes utilizing a thin inner wall and
an air gap separating the inner and outer wall may be used to insulate
the exhaust system and reduce the thermal mass, minimizing heat lost to
the walls and decreasing the time necessary to reach operational
temperatures after a cold start. Mechanical insulation applied to the
exterior of exhaust components, including exhaust catalysts, is readily
available and can minimize heat loss to the environment and help retain
heat within the catalyst as operation transitions to lighter loads and
lower exhaust temperatures. Integrating the DOC, DPF, and SCR
substrates into a single exhaust assembly can also assist with
retaining heat energy.
EPA is evaluating several passive thermal management strategies in
the diesel technology feasibility demonstration program, including a
light-off SCR located closer to the exhaust turbine (see Section
III.A.1.v), use of an air-gap exhaust manifold and downpipe, and use of
an insulated and integrated single-box system for the DOC, DPF, and
downstream SCR/ASC. We will evaluate their combined ability to reduce
the time to reach light-off temperature and achieve higher exhaust
temperatures that should contribute to NOX reductions during
low-load operation. We welcome comment on the current adoption of
passive thermal management strategies, including any available data on
the cost, effectiveness, and limitations.
iii. Active Thermal Management
Active thermal management involves using the engine and associated
hardware to maintain and/or increase exhaust temperatures. This can be
accomplished through a variety of means, including engine throttling,
heated aftertreatment systems, and flow bypass systems. Combustion
phasing can also be used for thermal management and is discussed in the
following section.
Diesel engines operate at very low fuel-air ratios (i.e., with
considerable excess air) at light-load conditions. This causes
relatively cool exhaust to flow through the exhaust system at low
loads, which cools the catalyst substrates. This is particularly true
at idle. It is also significant at moderate-to-high engine speeds with
little or no engine power, such as when a vehicle is coasting down a
hill. Air flow through the engine can be reduced by induction and/or
exhaust throttling. All heavy-duty diesel engines are equipped with an
electronic throttle control (ETC) within the induction system and most
are equipped with a variable-geometry-turbine (VGT) turbocharger, and
these systems can be used to throttle the induction and exhaust system,
respectively, at light-load conditions. However, throttling reduces
volumetric efficiency, and thus has a trade-off relative to
CO2 emissions.
Heat can be added to the exhaust and aftertreatment systems by
burning fuel in the exhaust system or by using electrical heating (both
of which can increase the SCR efficiency). Burner systems use an
additional diesel fuel injector in the exhaust to combust fuel and
create additional heat energy in the exhaust system. Electrically
heated catalysts use electric current applied to a metal foil
monolithic structure in the exhaust to add heat to the exhaust system.
In addition, heated higher-pressure urea dosing systems improve the
decomposition of urea at low exhaust temperatures and thus allow urea
injection to occur at lower exhaust temperature (i.e., at less than 180
[deg]C). At light-load conditions with relatively high flow/low
temperature exhaust, considerable fuel energy or electric energy would
be needed for these systems. This would likely cause a considerable
increase in CO2 emissions with conventional designs.
[[Page 3314]]
Exhaust flow bypass systems can be used to manage the cooling of
exhaust during cold start and low load operating conditions. For
example, significant heat loss occurs as the exhaust gases flow through
the turbocharger turbine. Turbine bypass valves allow exhaust gas to
bypass the turbine and avoid this heat loss at low loads when
turbocharging requirements are low. In addition, an EGR flow bypass
valve would allow exhaust gases to bypass the EGR cooler when it is not
required.
We welcome comment on active thermal management strategies,
including any available data on the cost, effectiveness, and
limitations, as well as information about its projected use for the
2024 to 2030 timeframe.
iv. Variable Valve Actuation (VVA)
Both gasoline and diesel engines control the flow of air and
exhaust into and out of the engine by opening and closing camshaft-
actuated intake and exhaust valves at specific times during the
combustion cycle. VVA includes a family of valvetrain designs that
alter the timing and/or lift of the intake valve, exhaust valve. These
adjustments can reduce pumping losses, increase specific power, and
control the level of residual gases in the cylinder. They can also
reduce NOX emissions as discussed below.
VVA has been adopted in light-duty vehicles to increase an engine's
efficiency and specific power. It has also been used as a thermal
management technology to open exhaust valves early to increase heat
rejection to the exhaust and heat up exhaust catalysts more quickly.
The same early exhaust valve opening (EEVO) has been applied to the
Detroit DD8 \58\ to aid in DPF regeneration, but a challenge with this
strategy for maintaining aftertreatment temperature is that it reduces
cycle thermal efficiency, and thus can contribute to increased
CO2 emissions.
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\58\ Detroit. ``DETROIT DD8'' Available online: https://demanddetroit.com/engines/dd8/.
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During low-load operation of diesel engines, exhaust temperatures
can drop below the targeted catalyst temperatures and the exhaust flow
can thus cause catalyst cooling. Cylinder deactivation (CDA), late
intake valve closing (LIVC), and early intake valve closing (EIVC) are
three VVA strategies that can also be used to reduce airflow through
the exhaust system at light-load conditions, and have been shown to
reduce the CO2 emissions trade-off compared to use of the
ETC and/or VGT for throttling.59 60
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\59\ Ding, C., Roberts, L., Fain, D., Ramesh, A.K., Shaver,
G.M., McCarthy, J., et al. (2015). ``Fuel efficient exhaust thermal
management for compression ignition engines via cylinder
deactivation and flexible valve actuation.'' Int. J .Eng. Res.
doi:10.1177/1468087415597413.
\60\ Neely, G.D., Sharp, C.A., Pieczko, M.S., McCarthy, J.E.
(2019). ``Simultaneous NOX and CO2 Reduction
for Meeting Future CARB Standards Using a Heavy Duty Diesel CDA NVH
Strategy.'' SAE International Journal of Engines, Paper No. JENG-
2019-0075.
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Since we are particularly concerned with catalyst performance at
low loads, EPA is evaluating two valvetrain-targeted thermal management
strategies that reduce airflow at light-load conditions (i.e., less
than 3-4 bar BMEP): CDA and LIVC. Both strategies force engines to
operate at a higher fuel-air ratio in the active cylinders, which
increases exhaust temperatures, with the benefit of little or no
CO2 emission increase and with potential for CO2
emission decreases under some operating conditions. The key difference
between these two strategies is that CDA completely removes airflow
from a few cylinders with the potential for exhaust temperature
increases of up to 60 [deg]C at light loads, while LIVC reduces airflow
from all cylinders with up to 40 [deg]C hotter exhaust temperatures.
We recognize that one of the challenges of CDA is that it requires
proper integration with the rest of the vehicle's driveline. This can
be difficult in the vocational vehicle segment where the engine is
often sold by the engine manufacturer (to a chassis manufacturer or
body builder) without knowing the type of transmission or axle used in
the vehicle or the precise duty cycle of the vehicle. The use of CDA
requires fine tuning of the calibration as the engine moves into and
out of deactivation mode to achieve acceptable noise, vibration, and
harshness (NVH). Additionally, CDA could be difficult to apply to
vehicles with a manual transmission because it requires careful gear
change control.
We are in the process of evaluating CDA as part of our feasibility
demonstration. In addition to laboratory demonstrations of CDA's
emission reduction potential, we are evaluating the cost to develop,
integrate, and calibrate the hardware. We plan to evaluate both dynamic
CDA with individual cylinder control that requires fully-variable valve
actuation hardware, and fixed CDA that can be achieved by much simpler
valve deactivation hardware commonly used in exhaust braking
technology. The relatively simple fixed CDA system would be lower cost
and we expect it would apply to a smaller range of operation with less
potential for CO2 benefits.
We believe that LIVC may provide emission reductions similar to
fixed CDA with the added benefits of no NVH concerns and that a
production-level system could be cost-competitive to CDA. Thus, we will
continue to evaluate it as a potential technological alternative to
CDA.\61\ We welcome comment on CDA and LIVC strategies for
NOX reduction, including any available data on the cost,
effectiveness, and technology limitations.
---------------------------------------------------------------------------
\61\ McDonald, Joseph. ``Engine Modeling of LIVC for Heavy-duty
Diesel Exhaust Thermal Management at Light-load Conditions''
Memorandum to Docket EPA-HQ-OAR-2019-0055. November 21, 2019.
---------------------------------------------------------------------------
v. Dual-SCR Catalyst System
Another NOX reduction strategy we are evaluating is an
alternative aftertreatment configuration known as a light-off or dual
SCR system, which is a variation of passive thermal management. This
system maintains a layout similar to the conventional SCR configuration
discussed earlier, but integrates an additional small-volume SCR
catalyst, close-coupled to the turbocharger's exhaust turbine outlet
(Figure 1). This small SCR catalyst could be configured with or without
an upstream DOC.
The benefits of this design result from its ability to warm up
faster as a result of being closer to the engine. Such upstream SCR
catalysts are also designed to have smaller substrates with lower
density, both of which reduce the thermal inertia and allow them to
warm up even faster. The upstream system would reach a temperature
where urea injection could very soon after engine startup, followed
quickly by catalyst light-off. These designs also require less input of
heat energy into the exhaust to maintain exhaust temperatures during
light-load operation. The urea injection to the close-coupled, light-
off SCR can also be terminated once the second, downstream SCR reaches
operational temperature, thus allowing additional NOX to
reach the DOC and DPF to promote passive regeneration (soot oxidation)
on the DPF.
[[Page 3315]]
[GRAPHIC] [TIFF OMITTED] TP21JA20.038
EPA is evaluating this dual-SCR catalyst system technology as part
of our diesel technology feasibility demonstration program. One concern
that has been raised about this technology is the durability challenge
associated with placing an SCR catalyst upstream of the DPF. To address
this concern, a dual-SCR system is currently being aged at SwRI to an
equivalent of 850,000 miles to better understand the impacts of
catalyst degradation at much longer in-use operation than captured by
today's regulatory useful life. We are utilizing an accelerated aging
process \62\ to thermally and chemically age the catalyst and will test
catalyst performance at established checkpoints to measure the emission
reduction performance as a function of miles. We plan to test this
dual-SCR system individually as well as in combination with the thermal
management strategies described in this section.
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\62\ See Section III.F.4 for a description of the accelerated
aging process used.
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One of the design constraints that will be explored with EPA's
evaluation of advanced SCR technology is nitrous oxide (N2O)
emissions. N2O emissions are affected by the temperature of
the SCR catalyst, SCR catalyst formulation, diesel exhaust fluid dosing
rates and the makeup of NO and NO2 upstream of the SCR
catalyst. Limiting N2O emissions is important because
N2O is a greenhouse gas and because highway heavy-duty
engines are subject to the 0.10 g/hp-hr standard set in HD GHG Phase 1
rule.
vi. Aftertreatment Durability
The aging mechanisms of diesel exhaust aftertreatment systems are
complex and include both chemical and hydrothermal changes. Aging
mechanisms on a single component can also cascade into impacts on
multiple catalysts and catalytic reactions within the system. Some
aging impacts are fully reversible (i.e., the degradation can be undone
under certain conditions). Other aging impacts are only partially
reversible, irreversible, or can only be reversed with some form of
intervention (e.g., changes to engine calibration to alter exhaust
temperature and/or composition). A docket memo entitled ``Diesel
Exhaust Emission Control Systems'' provides a more detailed summary of
hydrothermal and chemical aging of diesel exhaust catalysts.\63\
---------------------------------------------------------------------------
\63\ McDonald, Joseph. ``Diesel Exhaust Emission Control
Systems'' Memorandum to Docket EPA-HQ-OAR-2019-0055. November 13,
2019.
---------------------------------------------------------------------------
Our holistic approach in CTI includes a reevaluation of current
useful life values (see Section III.D), which could necessitate further
improvements to prevent the loss of aftertreatment function at higher
mileages. These potential improvements fall into the following
categories:
Designing excess capacity into the catalyst (e.g.,
increased catalyst volume, increased catalyst cell density, increased
surface area for active materials in washcoating) so physical or
chemical degradation of the catalyst does not reduce its performance.
Continued improvements to catalyst materials (such as the
washcoat and substrate) to make them more durable (see more detailed
discussion in section III.A.1.i).
[cir] Use of additives and other improvements specifically to
prevent thermal or chemical breakdown of the zeolite structure within
SCR coatings.
[[Page 3316]]
[cir] Use of washcoat additives and other improvements to increase
PGM dispersion, reduce PGM particle size, reduce PGM mobility and
reduce agglomeration within the DOC and DPF washcoatings.
Direct fuel dosing downstream of the light-off SCR during
active DPF regeneration to reduce exposure of the light-off SCR to fuel
compounds and contaminants.
Improvements to catalyst housings and substrate matting
material to minimize vibration and prevent leaks of exhaust gas.
Adjusting engine calibration and emissions control system
design to minimize operation that would damage the catalyst (e.g.,
improved control of DPF active regeneration, increased passive DPF
regeneration, fuel dosing downstream of initial light-off SCR).
Use of specific engine calibration strategies to remove
sulfur compounds from the SCR system.
Use of exhaust system designs that facilitate periodic DPF
ash maintenance.
Diagnosis and prevention of upstream engine malfunctions
that can potentially damage exhaust aftertreatment components.
Increased SCR catalyst capacity with incrementally improved zeolite
coatings would be the primary strategies for improving NOX
control for a longer useful life. SCR capacity can be increased by
approximately one-third through the use of a light-off SCR substrate
combined with a downstream substrate with a volume roughly equivalent
to the average volume of today's systems and with moderately increased
catalytic activity due to continued incremental improvements to
chabazite and other zeolite coatings used for SCR. Total SCR volume
would thus increase by approximately one-third relative to today's
systems. SCR capacity can also be increased in the downstream SCR
system through the use of thin-wall (4 to 4.5 mil), high cell density
(600 cells-per-square-inch) substrates.
Chemical aging of the DOC, DPF, and SCR can be reduced by the
presence of an upstream light-off SCR. Transport and adsorption of S,
P, Ca, Zn, Mg, Na, and K compounds and other catalyst poisons are more
severe for the initial catalyst within an emissions control system and
tend to reduce in severity for catalysts positioned further downstream.
Further evolutionary improvements to the DOC washcoating materials to
increase PGM dispersion and reduce PGM mobility and agglomeration would
be anticipated for meeting increased useful life requirements.
The primary strategy for maintaining DPF function to a longer
useful life would be through design of integrated systems that
facilitate easier removal of the DPF for ash cleaning at regular
maintenance intervals. Accommodation of DPF removal for ash maintenance
is already incorporated into existing diesel exhaust system
designs.\64\ Improvements to catalyst housings and substrate matting
material could be expected for all catalyst substrates within the
system. Integration into a box-muffler type system could also be
expected within the 2027 timeframe for all catalyst components (except
for the initial close-coupled SCR) in order to improve passive thermal
management.
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\64\ Eberspacher. ``1BOX Product Literature.''
---------------------------------------------------------------------------
vii. Closed Crankcases
During combustion, gases can leak past the piston rings sealing the
cylinder and into the crankcase. These gases are called blowby gases
and generally include unburned fuel and other combustion products.
Blowby gases that escape from the crankcase are considered crankcase
emissions.\65\ Current regulations restrict the discharge of crankcase
emissions directly into the ambient air, and blowby gases from gasoline
engine crankcases have been controlled for many years by sealing the
crankcase and routing the gases into the intake air through a positive
crankcase ventilation (PCV) valve. However, there have been concerns
about applying a similar technology for diesel engines. For example,
high PM emissions venting into the intake system could foul
turbocharger compressors. As a result of this concern, diesel-fueled
and other compression-ignition engines equipped with turbochargers (or
other equipment) were not required to have sealed crankcases.\66\ For
these engines, manufacturers are allowed to vent the crankcase
emissions to ambient air as long as they are measured and added to the
exhaust emissions during all emission testing.
---------------------------------------------------------------------------
\65\ 40 CFR 86.402-78.
\66\ 40 CFR 86.007-11(c).
---------------------------------------------------------------------------
Because all new highway heavy-duty diesel engines on the market
today are equipped with turbochargers, they are not required to have
closed crankcases under the current regulations. Manufacturer
compliance data indicate a portion of current highway heavy-duty diesel
engines have closed crankcases, which suggests that some heavy-duty
engine manufacturers have developed systems for controlling crankcase
emissions that do not negatively impact the turbocharger. EPA is
considering provisions to require a closed crankcase ventilation system
for all highway compression-ignition engines to prevent crankcase
emissions from being emitted directly to the atmosphere. These
emissions could be routed upstream of the aftertreatment system or back
into the intake system. Our reasons for considering this requirement
are twofold.
While the exception in the current regulations for certain
compression-ignition engines requires manufacturers to quantify their
engines' crankcase emissions during certification, they report non-
methane hydrocarbons in lieu of total hydrocarbons. As a result,
methane emissions from the crankcase are not quantified. Methane
emissions from diesel-fueled engines are generally low; however, they
are a concern for compression-ignition-certified natural gas-fueled
heavy-duty engines because the blowby gases from these engines have a
higher potential to include methane emissions. EPA proposed to require
that all natural gas-fueled engines have closed crankcases in the
Heavy-Duty Phase 2 GHG rulemaking, but opted to wait to finalize any
updates to regulations in a future rulemaking (81 FR at 73571, October
25, 2016).
In addition to our concern of unquantified methane emissions, we
believe another benefit to closed crankcases would be better in-use
durability. We know that the performance of piston seals reduces as the
engine ages, which would allow more blowby gases and could increase
crankcase emissions. While crankcase emissions are included in the
durability tests that estimate an engine's deterioration, those tests
were not designed to capture the deterioration of the crankcase. These
unquantified age impacts continue throughout the operational life of
the engine. Closing crankcases could be a means to ensure those
emissions are addressed long-term to the same extent as other exhaust
emissions.
EPA is conducting emissions testing of open crankcase systems and
will be developing the technology costs associated with a closed
crankcase ventilation system. We request comment, including any
available data, on the appropriateness and costs of requiring closed
crankcases for all heavy-duty compression-ignited engines.
viii. Fuel Quality
EPA has long recognized the importance of fuel quality on motor
vehicle emissions and has regulated fuel quality to enable compliance
with emission standards. In 1993 EPA
[[Page 3317]]
limited diesel sulfur content to a maximum of 500 ppm and put into
place a minimum cetane index of 40. Starting in 2006 with the
establishment of more stringent heavy-duty highway PM, NOX,
and HC emission standards, EPA phased-in a 15-ppm maximum diesel fuel
sulfur standard to enable heavy-duty diesel truck compliance with the
more stringent emission standards.
Recently an engine manufacturer raised concerns to EPA regarding
the metal content of highway diesel fuel.\67\ The engine manufacturer
observed higher than normal concentrations of alkali and alkaline earth
metals (i.e., Na, K, Ca, and Mg) in its highway diesel fuel samples.
These metals can lead to fouling of the aftertreatment control systems
and an associated increase in emissions. The engine manufacturer claims
that biodiesel is the source of the high metal content in diesel fuel,
and that higher biodiesel blends, such as B20, are the principal
problem. The engine manufacturer states that the engine's warranty will
be voided if biodiesel blends greater than 5 percent (B5) are used.
---------------------------------------------------------------------------
\67\ Recker, Alissa, ``Fuel Quality Impacts on Aftertreatment
and Engine;'' Daimler Trucks, July 29, 2019.
---------------------------------------------------------------------------
Over the last decade, biodiesel content in diesel fuel has
increased under the Renewable Fuels Standard. In 2010, less than 400
million gallons of biodiesel were consumed, whereas in 2018, over 2
billion gallons of biodiesel were being blended into diesel fuel. While
the average biodiesel content in diesel fuel was around 3.5 percent in
2018, biodiesel is being blended on per batch basis into highway diesel
fuel at levels ranging from 0 to 20 volume percent.
EPA compared data collected by the National Renewable Energy
Laboratory (NREL) on the metal content of biodiesel to that provided by
the engine manufacturer. The NREL data showed fewer samples exceeding
the maximum metals concentration limits contained in ASTM D6751-18,
although in both cases the small sample sizes could be biasing the
results.\68\ Numerous studies have collected and analyzed emission data
from diesel engines operated on biodiesel blended diesel with
controlled amounts of metal content.\69\ Some of these studies show an
impact on emissions, while others do not.
---------------------------------------------------------------------------
\68\ Wyborny, Lester. ``References Regarding Metals in Diesel
and Biodiesel Fuels.'' Memorandum to Docket EPA-HQ-OAR-2019-0055.
November 11, 2019
\69\ Id.
---------------------------------------------------------------------------
EPA has also heard concerns from some stakeholders that water in
highway diesel fuel meeting the ASTM D975 water and sediment limit of
0.05 volume percent can cause premature failure of fuel injectors due
to corrosion from the presence of dissolved alkali and alkaline earth
metals.
EPA requests comment on concerns regarding metal and water
contamination in highway diesel fuel and on the potential role of
biodiesel in this contamination. EPA seeks data on the levels of these
contaminants in fuels, including the prevalence of contamination, and
on the associated degradation and failure of engines and aftertreatment
function.
2. Gasoline Engine Technologies Under Consideration
Automobile manufacturers have made progress reducing
NOX, CO and HC from gasoline-fueled passenger cars and
light-duty trucks. Similar to the DOC and SCR catalysts described
previously, three-way catalysts perform at a very high level once
operating temperature is achieved. There is a short window of operation
following a cold start when the exhaust temperature is low and the
three-way catalyst has not reached light-off, resulting in a temporary
spike in CO, HC, and NOX. A similar reduction in catalyst
efficiency can occur due to sustained idle or creep-crawl operation
that vehicles may experience in dense traffic if the catalyst
configuration does not maintain temperatures above the light-off
temperature. Gasoline engines generally operate near stoichiometric
fuel-air ratios, creating optimal conditions for a three-way catalyst
to simultaneously convert CO, NO, and HC to CO2,
N2, and H2O. However, as introduced in Section
II.B.2, heavy-duty engine manufacturers often implement enrichment-
based strategies for engine and catalyst protection at high load, which
reduces the effectiveness of the three-way catalyst and increases
emissions. The following section describes technologies we believe can
address these emissions increases.
i. Technologies To Reduce Exhaust Emissions
As mentioned in Section II.B.2, most chassis-certified heavy-duty
vehicles are subject to EPA's light-duty Tier 3 program and these
vehicles have adopted many of the emissions technologies from their
light-duty counterparts (79 FR 23414, April 28, 2014). To meet these
Tier 3 emission standards, manufacturers have reduced the time for the
catalyst to reach operational temperature by implementing cold-start
strategies to reduce light-off time and moved the catalyst closer to
the exhaust valve. Manufacturers have not widely adopted the same
strategies for their engine-certified products. In particular, we
believe there are opportunities to reduce cold-start and low-load
emissions from engine-certified heavy-duty gasoline engines by adopting
the following strategies to accelerate light-off and keep the catalyst
warm:
Close-couple the catalyst to the engine
Improved catalyst material and loading
Improved exhaust system insulation
Additionally, we believe material improvements to the catalyst,
manifolds, and exhaust valves could increase their ability to withstand
higher exhaust temperatures and would therefore reduce the need for
enrichment-based protection modes that result in elevated emissions
under high-load operation. Catalyst technology continues to advance to
meet engine manufacturers' demand for earlier and sustained light-off
for low-load emission control, as well as increased maximum temperature
thresholds allowing catalysts to withstand close-coupling and elevated
exhaust temperatures during high load.
Similar to EPA's diesel engine demonstration project, we are
testing heavy-duty gasoline engines and technologies that are available
today on a range of Class 3 to 7 vehicles. The three engines in this
test program represent a majority of the heavy-duty gasoline market and
include both engine- and chassis-certified configurations. Emissions
performance of engine- and chassis-certified configurations are being
evaluated using chassis-dynamometer and real-world portable emissions
measurement system (PEMS) testing. Early testing showed significant
differences in emissions performance between engine-certified and
chassis-certified configurations (primarily as a result of differences
in catalyst location).\70\
---------------------------------------------------------------------------
\70\ Mitchell, George, ``EPA's Medium Heavy-Duty Gasoline
Vehicle Emissions Investigation''. February 2019.
---------------------------------------------------------------------------
Moving the catalyst into a close-coupled configuration is one
approach adopted for chassis-certified gasoline engines to warm-up and
activate the catalyst during cold-start and light load operation.
Close-coupled locations may increase the catalysts' exposure to high
exhaust temperatures, especially for heavy-duty applications that
operate frequently in high-load operation. However, this can be
overcome by adopting improved catalyst materials or identifying an
optimized, closer-coupled catalyst location that enhances
[[Page 3318]]
warm-up without extended time at high temperatures. We welcome comment
on other performance characteristics of engine and aftertreatment
technologies from chassis-certified vehicles when applied to engine-
certified products, specifically placing the catalyst in a location
more consistent with chassis-certified applications.
We also welcome comment on heavy-duty gasoline engine technology
costs. We plan to develop our technology cost estimates for the NPRM
based on information from light-duty and chassis-certified heavy-duty
pick-up trucks and vans that are regulated under EPA's Tier 3
program.\71\
---------------------------------------------------------------------------
\71\ EPA. ``Control of Air Pollution from Motor Vehicles: Tier 3
Motor Vehicle Emission and Fuel Standards Final Rule Regulatory
Impact Analysis'' EPA-420-R-14-005, February 2014, available online
at: https://nepis.epa.gov/Exe/ZyPDF.cgi/P100ISWM.PDF?Dockey=P100ISWM.PDF.
---------------------------------------------------------------------------
Finally, we believe there may be opportunity for further reductions
in PM from heavy-duty gasoline engines. Gasoline PM forms under high-
load, rich fuel-air operation and is more prevalent as engines age and
parts wear. Strategies to reduce or eliminate fuel-air enrichment under
high-load operation would reduce PM formation. In addition, gasoline
particulate filters (GPF), which serve the same function as DPFs on
diesel engines, may be an effective means of PM reduction for heavy-
duty gasoline engines as well.\72\ We request comment on the need for
more stringent PM standards for heavy-duty gasoline engines.
---------------------------------------------------------------------------
\72\ Jiacheng Yang, Patrick Roth, Thomas D. Durbin, Kent C.
Johnson, David R. Cocker, III, Akua Asa-Awuku, Rasto Brezny, Michael
Geller, and Georgios Karavalakis (2018) ``Gasoline Particulate
Filters as an Effective Tool to Reduce Particulate and Polycyclic
Aromatic Hydrocarbon Emissions from Gasoline Direct Injection (GDI)
Vehicles: A Case Study with Two GDI Vehicles'' Environmental Science
& Technology doi: 10.1021/acs.est.7b05641.
---------------------------------------------------------------------------
ii. Technologies To Address Evaporative Emissions
As exhaust emissions from gasoline engines continue to decrease,
evaporative emissions become an increasingly significant contribution
to overall HC emissions from gasoline-fueled vehicles. To evaluate the
evaporative emission performance of current production heavy-duty
gasoline vehicles, EPA tested two heavy-duty vehicles over running
loss, hot soak, three-day diurnal, on-board refueling vapor recovery
(ORVR) and static test procedures. These engine-certified
``incomplete'' vehicles meet the current heavy-duty evaporative running
loss, hot soak, three-day diurnal emission requirements. However, as
they are certified as incomplete vehicles, they are not required to
control refueling emissions and do not have ORVR systems. Results from
the refueling testing confirm that these vehicles have much higher
refueling emissions than gasoline vehicles with ORVR
controls.73 74
---------------------------------------------------------------------------
\73\ SGS-Aurora, Eastern Research Group, ``Light Heavy-Duty
Gasoline Vehicle Evaporative Emissions Testing.'' EPA-420-R-19-017.
December 2019.
\74\ U.S. Environmental Protection Agency. ``Summary of ``Light
Heavy-Duty Gasoline Vehicle Evaporative Emissions Test Program'' ''
EPA-420-S-19-002. December 2019.
---------------------------------------------------------------------------
EPA is evaluating the opportunity to extend the usage of the
refueling evaporative emission control technologies already implemented
in complete heavy-duty gasoline vehicles to the engine-certified
incomplete gasoline vehicles in the over-14,000 lb. GVWR category. The
primary technology we are considering is the addition of ORVR, which
was first introduced to the chassis-certified light-duty and heavy-duty
applications beginning in MY 2000 (65 FR 6698, February 10, 2000). An
ORVR system includes a carbon canister, which is an effective
technology designed to capture HC emissions during refueling events
when liquid gasoline displaces HC vapors present in the vehicle's fuel
tank as the tank is filled. Instead of releasing the HC vapors into the
ambient air, ORVR systems recover these HC vapors and store them for
later use as fuel to operate the engine.
The fuel systems on these over-14,000 pound GVWR incomplete heavy-
duty gasoline vehicles are similar to complete heavy-duty vehicles that
are already required to incorporate ORVR. These incomplete vehicles may
have slightly larger fuel tanks than most chassis-certified (complete)
heavy-duty gasoline vehicles and are somewhat more likely to have dual
fuel tanks. These differences may require a greater ORVR system storage
capacity and possibly some unique accommodations for dual tanks (e.g.,
separate fuel filler locations), but we expect they will maintain a
similar design. We are aware that some engine-certified products for
over-14,000 GVWR gasoline vehicles are sold as incomplete chassis
without complete fuel systems. Thus, the engine-certifying entity
currently may not know or be in control of the filler system location
and integration limitations for the final vehicle body configuration.
This dynamic has been addressed for other emission controls through a
process called delegated assembly--where the certifying manufacturer
delegates certain assembly obligations to a downstream
manufacturer.\75\
---------------------------------------------------------------------------
\75\ See 40 CFR 1068.260 and 1068.261.
---------------------------------------------------------------------------
We request comment on EPA expanding our ORVR requirements to
incomplete heavy-duty vehicles. We are particularly interested in the
challenges of multiple manufacturers to appropriately implement ORVR
systems on the range of gasoline-fueled vehicle products in the market
today. We also seek comment on refueling test procedures, including the
appropriateness of engineering analysis to adapt existing test
procedures that were developed for complete vehicles to apply for
incomplete vehicles.
3. Emission Monitoring Technologies
As heavy-duty engine performance has become more sophisticated, the
industry has developed increasingly advanced sensors on board the
vehicle to monitor the performance of the engine and emission controls.
For the CTI, we are particularly interested in recent developments in
the performance of zirconia NOX sensors that manufacturers
are currently using to measure NOX concentrations and
control SCR urea dosing. EPA has identified applications where we
believe the use of these and other onboard sensors could enhance and
potentially streamline existing EPA programs. We discuss those
applications in Section III.F.
We recognize that one of the challenges to relying on sensors for
these applications is the availability of NOX sensors that
are continuously operational and accurate at low concentration levels.
As a result, we are beginning a study to assess the accuracy,
repeatability, noise, interferences, and response time of current
NOX sensors. However, we encourage commenters to submit
information to help us project whether the state of NOX
sensor technology in the 2027 timeframe would be sufficient to enable
such programs. We also request comment on the durability of
NOX sensors, as well as specific maintenance or operational
strategies that could be considered to substantially extend the life of
these components and any regulatory barriers to implementing these
strategies.
In addition to the performance of onboard NOX sensors,
we are following the industry's increasing adoption of telematics
systems that could enable the manufacturer to communicate with the
vehicle's onboard computer in real-time. We request comment on the
prevalence of telematics, the range of information that can be shared
over-the-air, and limitations of the technology today. As we describe
in Section III.F.3, the combination of advanced onboard sensors and
telecommunications could
[[Page 3319]]
facilitate the ability to determine tailpipe NOX emissions
of the vehicle in-use to reduce compliance burden in the future. We
also request comment on the potential for alternative communication
approaches to be used. For example, for vehicles not equipped with
telematics, would manufacturers still be able to collect data from the
vehicle during service at their dealerships?
Finally, we request comment on whether and how improved
communication systems could be leveraged by manufacturers or in state,
local, or tribal government programs to promote emission reductions
from the heavy-duty fleet.
4. Hybrid, Battery-Electric, and Fuel Cell Vehicles
Hybrid technologies that recover and store braking energy have been
used extensively in light-duty applications as fuel saving features.
They are also being adopted in certain heavy-duty applications, and
their heavy-duty use is projected to increase significantly over the
next several years as a result of the HD Phase 2 GHG standards.
However, the HD Phase 2 rule also identified plug-in hybrid vehicles
(where the battery can be charged from an external power source),
battery-electric vehicles (where the vehicle has no engine), and fuel
cell vehicles (where the power supply is not an internal combustion
engine, or ICE) as more advanced technologies that were not projected
to be adopted in the heavy-duty market without additional incentives
(81 FR 73497, October 25, 2016).
Hybrid technologies range from mild hybrids that recover braking
energy for accessory use (often using a supplemental 48V electrical
battery), to fully-hybrid vehicles with integrated electric motors at
the wheels capable of propelling the vehicle with the engine turned
off; and their emissions impact varies by integration level and design.
Existing heavy-duty hybrid technologies have the potential to decrease
or increase NOX emissions, depending on how they are
designed. For example, a hybrid system can reduce NOX
emissions if it eliminates idle operation or uses the recovered
electrical energy to heat aftertreatment components. In contrast, it
can increase NOX emissions if it reduces the engine's
ability to maintain sufficiently high aftertreatment temperatures
during low-load operation.
Since battery-electric and hydrogen fuel cell vehicles do not have
ICEs, they have zero tailpipe emissions of NOX. We request
comment on whether, and if so how, the CTI should project use of these
more advanced technologies as NOX reduction technologies.
These technologies as well as the more conventional hybrid technologies
are collectively referred to as advanced powertrain technologies for
the remainder of this discussion.
We are focused on three objectives related to these advanced
powertrain technologies in CTI:
1. To reflect market adoption of these technologies in the 2027 and
beyond timeframe as accurately as possible in the baseline analysis
(i.e., without reflecting potential responses from CTI requirements),
2. To address barriers to market adoption due to EPA emissions
certification requirements,
3. To understand whether and how any incentives may be appropriate
given the substantial tailpipe emission reduction potential of these
technologies.
The choice of which powertrain technology to select for a
particular heavy-duty vehicle application depends on factors such as
number of miles traveled per day, accessibility of refueling
infrastructure (i.e., charging stations, hydrogen fuel cell refilling
stations), and driver preferences (e.g., noise level associated with
electric versus ICEs).To address the first focus area, we are currently
conducting stakeholder outreach and reviewing published projections of
advanced emissions technologies. Our initial review of information
suggests that there are a wide range of advanced powertrain
technologies available today, including limited production of more than
100 battery-electric or fuel cell vehicle models offering zero tailpipe
emissions.\76\ Looking forward, a variety of factors will influence the
extent to which hybrid and zero emissions heavy-duty vehicles are
available for purchase and enter the market.77 78 Of these,
the lifetime total cost of ownership (TCO), which includes maintenance
and fuel costs, is likely a primary factor. Initial information
suggests that TCO for light- and medium heavy-duty battery-electric
vehicles could reach cost parity with diesel in the early 2020s, while
heavy heavy-duty battery-electric or hydrogen vehicles are likely to
reach cost parity with diesel closer to the 2030 timeframe.\79\ The TCO
for hybrid technologies, and its relation to diesel vehicles, will vary
based on the specifics of the hybrid system (e.g., cost and benefits of
a 48V battery versus an integrated electric motor).
---------------------------------------------------------------------------
\76\ ICCT (2019) ``Estimating the infrastructure needs and costs
for the launch of zero-emissions trucks''; available online at:
https://theicct.org/publications/zero-emission-truck-infrastructure.
\77\ McKinsey (2017) ``New reality: electric trucks and their
implications on energy demand''; available online at: https://www.mckinsey.com/industries/oil-and-gas/our-insights/a-new-reality-electric-trucks.
\78\ NACFE (2018) Guidance Report: Electric Trucks--Where They
Make Sense; available online at: https://nacfe.org/report-library/guidance-reports/.
\79\ ICCT (2019) ``Estimating the infrastructure needs and costs
for the launch of zero-emissions trucks''; available online at:
https://theicct.org/publications/zero-emission-truck-infrastructure.
---------------------------------------------------------------------------
Beyond TCO, considerations such as noise levels, vehicle weight,
payload capacity, operational range, charging/refueling time, safety,
and other driver preferences may influence the rate of market
entry.80 81 State and local activities, such as the Advanced
Clean Trucks rulemaking underway in California could also influence the
market trajectory for battery-electric and fuel cell technologies.\82\
EPA requests comment on the likely market trajectory for advanced
powertrain technologies in the 2020 through 2045 timeframe. Commenters
are encouraged to provide data supporting their perspectives on
reasonable adoption rates EPA could use for hybrid, battery-electric,
and fuel cell heavy-duty vehicles relative to the full heavy-duty
vehicle fleet in specific time periods (e.g., early 2020s, late 2020s,
2030, 2040, 2050).
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\80\ McKinsey (2017) ``New reality: electric trucks and their
implications on energy demand''; available online at: https://www.mckinsey.com/industries/oil-and-gas/our-insights/a-new-reality-electric-trucks.
\81\ NACFE (2018) Guidance Report: Electric Trucks--Where They
Make Sense; available online at: https://nacfe.org/report-library/guidance-reports/.
\82\ For more information on this proposed rulemaking in
California see: https://ww2.arb.ca.gov/rulemaking/2019/advancedcleantrucks?utm_medium=email&utm_source=govdelivery.
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For addressing potential barriers to market, stakeholders
previously expressed concern that the engine-focused certification
process for criteria pollutant emissions does not provide a pathway for
hybrid powertrains to demonstrate NOX reductions from hybrid
operations during certification. As such, we plan to propose an update
to our powertrain test procedure for hybrids, previously developed as
part of the HD Phase 2 rulemaking for greenhouse gas emissions, so that
it can be applied to criteria pollutant certification.83 84
We are interested in whether a hybrid powertrain test procedure
addresses concerns with certifying the full range of heavy-duty hybrid
products, or if other options might be useful for specific products,
such as mild hybrid systems. If
[[Page 3320]]
stakeholders view alternative options as useful, then we request input
on what those options might include.
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\83\ 40 CFR 1036.505.
\84\ 40 CFR 1036.510.
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We are also aware that current OBD requirements necessitate close
cooperation between engine and hybrid system manufacturers for
certification, and the process has proven sufficiently burdensome such
that few alliances have been pursued to-date. We are interested in
better understanding this potential barrier to heavy-duty hybrid
systems, and any potential opportunities EPA could consider to address
it.
Finally, related to the area of incentives, we are exploring simple
approaches, such as emission credits, targeted for specific market
segments for which technology development may be more challenging
(e.g., extended range battery-electric or fuel cell technologies). We
request comment on any barriers or incentives that EPA could consider
in order to better encourage emission reductions from these advanced
powertrain technologies. Commenters are encouraged to provide
information on the potential impacts of regulatory barriers or
incentives for all the advanced powertrain technologies discussed here
(hybrids, battery-electric, fuel cell), including the extent to which
these technologies may lower NOX and other criteria
pollutant emissions.
5. Alternative Fuels
In the case of alternative fuels, we have typically applied the
gasoline- and diesel-fueled engine standards to the alternatively-
fueled engines based on the combustion cycle of the alternatively-
fueled engine: Applying the gasoline-fueled standards to spark-ignition
engines and the diesel-fueled standards to compression-ignition
engines. This approach is often called ``fuel neutral.''
Most heavy-duty vehicles today are powered by diesel engines. These
engines have been optimized over many years to be reliable, durable,
and fuel efficient. Diesel fuel also has the advantage of being very
stable and having a high energy density. Gasoline-fueled engines are
the second-most popular choice, especially for light and medium heavy-
duty vehicles. They tend to be lighter and less expensive than diesel
engines although less durable and less fuel efficient. We do not expect
a shift in the market between diesel and gasoline as a result of the
CTI and we are requesting comment on the extent to which CTI could have
such effects.
With relatively low natural gas prices (compared to their peak
values) in recent years, the heavy-duty industry has become
increasingly interested in engines that are fueled with natural gas. It
has some emission advantages over diesel, with lower engine-out levels
of both NOX and PM. Several heavy-duty CNG engines have been
certified with NOX levels better than 90 percent below US
2010 standards. However, because natural gas must be distributed and
stored under pressure, there are additional challenges to using it as a
heavy-duty fuel. We request comment on how natural gas should be
treated in the CTI, including the possible provision of incentives.
Dimethyl ether (DME) is a related alternative fuel that also shows
some promise for compression-ignition engines. It can be readily
synthesized from natural gas and can be stored at lower pressures. We
request comment on the extent to which the CTI should consider DME.
LPG is also used in certain lower weight-class urban applications,
such as airport shuttle buses, school buses, and emergency response
vehicles. LPG use is not extensive, nor do we project it to grow
significantly in the CTI timeframe. However, given its emission
advantages over diesel, we request comment on how LPG should be treated
in the CTI, particularly for vocational heavy-duty engines and
vehicles.
B. Standards and Test Cycles
EPA emission standards have historically applied with respect to
emissions measured while the engine or vehicle is operating over a
specific duty cycle. The primary advantage of this approach is that it
provides very repeatable emission measurements. In other words, the
results should be the same no matter when or where the test is
performed, as long as the specified test procedures are used. For
heavy-duty, these tests are generally performed on the engine without
the vehicle.
We continue to consider these pre-production upfront demonstrations
as the cornerstone of ensuring in-use emission compliance. On the other
hand, tying standards to specific test cycles opens the possibility of
emission controls being designed more to the test procedures than to
in-use operation. Since 2004, we have applied additional in-use
standards for diesel engines that allow higher emission levels but are
not limited to a specific duty cycle, and instead measure emissions
over real-world, non-prescribed driving routes that cover a range of
in-use operation.
In this section we describe the updates we are considering for our
duty-cycle program. We do not include specific values, but welcome
comments and data which will assist EPA in developing appropriate
standards to propose that could apply to the updated procedures we
present. We also welcome comments on the relative importance of
laboratory-based test cycle standards and standards that can be
evaluated with the whole vehicle.
1. Emission Standards for RMC and FTP Cycles
Heavy-duty engines are subject to brake-specific (g/hp-hr)
standards for emissions of NOX, PM, NMHC, and CO. These
standards must be met by all diesel engines over both the Federal Test
Procedure (FTP) cycle and the Ramped-Modal Cycle (RMC). Gasoline
engines are only subject to testing over an FTP cycle designed for
spark-ignition engines. The FTP cycles, which date back to the 1970s,
are composites of a cold-start and a hot-start transient duty cycle
designed to represent urban driving. The cold-start emissions are
weighted by one-seventh and the hot-start emissions are weighted by
six-sevenths.\85\ The RMC is a more recent cycle for diesel engines
that is a continuous cycle with ramped transitions between the thirteen
steady-state modes.\86\ The RMC does not include engine starting and is
intended to represent fully warmed-up operating modes not emphasized in
the FTP, such as sustained high speeds and loads.
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\85\ See 40 CFR 86.007-11 and 40 CFR 86.08-10.
\86\ See 40 CFR 1065.505.
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Based on available information, it is clear that application of the
diesel technologies discussed in Sections III.A.1 should enable
emission reductions of at least 50 percent compared to current
standards over the FTP and RMC cycles.87 88 Some estimates
suggest that emission reductions of 90 percent may be achievable across
the heavy-duty engine market by model year 2027. We request information
that would help us determine the appropriate levels of any new emission
standards for the FTP and RMC cycles.
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\87\ California Air Resources Board, ``Staff White Paper:
California Air Resources Board Staff Current Assessment of the
Technical Feasibility of Lower NOX Standards and
Associated Test Procedures for 2022 and Subsequent Model Year
Medium-Duty and Heavy-Duty Diesel Engines''. April 18, 2019.
Available online: https://ww3.arb.ca.gov/msprog/hdlownox/white_paper_04182019a.pdf.
\88\ Manufacturers of Emission Controls Association.
``Technology Feasibility for Model Year 2024 Heavy-Duty Diesel
Vehicles in Meeting Lower NOX Standards''. June 2019.
Available online: http://www.meca.org/resources/MECA_MY_2024_HD_Low_NOx_Report_061019.pdf.
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We are considering changes to the weighting factors for the FTP
cycle for heavy-duty engines. We have historically developed our test
cycles and weighting factors to reflect real-
[[Page 3321]]
world operation. However, we recognize both engine technology and in-
use operation can change over time. The current FTP weighting of cold-
start and hot-start emissions was adopted in 1980 (45 FR 4136, January
21, 1980). It reflects the overall ratio of cold and hot operation for
heavy-duty engines generally and does not distinguish by engine size or
intended use. Given the importance of this weighting factor, we request
comment on the appropriateness of the current weighting factors across
the engine categories.\89\ We are also interested in comment on how to
address any challenges manufacturers may encounter to implement changes
to the weighting factors.
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\89\ For instance, cold-start operation for line-haul tractors
may represent significantly less than \1/7\ of their total in-use
operation, yet cold-start operation may represent a higher fraction
of operation for other vocational vehicles.
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We have also observed an industry trend toward engine down-
speeding--that is, designing engines to do more of their work at lower
engine speeds where frictional losses are lower. To address this trend
for EPA's CO2 standards testing, we adopted new RMC
weighting factors for CO2 emissions in the Phase 2 final
rule (81 FR 73550, October 25, 2016). Since we believe these new
weighting factors better reflect in-use operation of current and future
heavy-duty engines, we request comment on applying these new weighting
factors for NOX and other criteria pollutants as well.
2. New Emission Test Cycles and Standards
Review of in-use data has indicated that SCR-based emission
controls systems for diesel engines are not functional over a
significant fraction of real-world operation due to low aftertreatment
temperatures, which are often the result of extended time at low load
and idle operation.90 91 92 Our current in-use testing
procedures (described in Section III.C) were not designed to capture
this type of operation. Test data collected as part of EPA's
manufacturer-run in-use testing program indicate that low-load
operation could account for more than half of the NOX
emissions from a vehicle over a given shift-day.\93\
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\90\ Hamady, Fakhri, Duncan, Alan. ``A Comprehensive Study of
Manufacturers In-Use Testing Data Collected from Heavy-Duty Diesel
Engines Using Portable Emissions Measurement System (PEMS)''. 29th
CRC Real World Emissions Workshop, March 10-13, 2019.
\91\ Sandhu, Gurdas, et al. ``Identifying Areas of High
NOX Operation in Heavy-Duty Vehicles''. 28th CRC Real-
World Emissions Workshop, March 18-21, 2018.
\92\ Sandhu, Gurdas, et al. ``In-Use Emission Rates for MY 2010+
Heavy-Duty Diesel Vehicles''. 27th CRC Real-World Emissions
Workshop, March 26-29, 2017.
\93\ Sandhu, Gurdas, et al. ``Identifying Areas of High
NOX Operation in Heavy-Duty Vehicles''. 28th CRC Real-
World Emissions Workshop, March 18-21, 2018.
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EPA is considering the addition of a low-load test cycle and
standard that would require diesel engine manufacturers to maintain the
emission control system's functionality during operation where the
catalyst temperatures have historically been below their operational
temperature. The addition of a low-load duty-cycle could complement the
expanded operational coverage of in-use testing requirements we are
also considering. We have been following CARB's low-load cycle
development in ``Stage 2'' of their Low NOX Demonstration
program. SwRI and NREL developed several candidate cycles with average
power and duration characteristics intended to test today's diesel
engine emission controls under three low-load operating conditions:
Transition from high- to low-load, sustained low-load, and transition
from low- to high-load.\94\ In September 2019, CARB selected the 90-
minute ``LLC Candidate #7'' as the final cycle they are considering for
their Low NOX Demonstration program.\95\ EPA requests
comment on the addition of a low-load cycle, the appropriateness of
CARB's Candidate #7 low-load cycle, or other engine operation a low-
load cycle should encompass, if adopted.
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\94\ California Air Resources Board. ``Heavy-Duty Low
NOX Program Public Workshop: Low Load Cycle
Development''. Sacramento, CA. January 23, 2019. Available online:
https://ww3.arb.ca.gov/msprog/hdlownox/files/workgroup_20190123/02-llc_ws01232019-1.pdf.
\95\ California Air Resources Board. ``Heavy-Duty Low
NOX Program: Low Load Cycle'' Public Workshop. Diamond
Bar, CA. September 26, 2019. Available online: https://ww3.arb.ca.gov/msprog/hdlownox/files/workgroup_20190926/staff/03_llc.pdf.
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In addition to adding a low-load cycle, CARB currently has an idle
test procedure and accompanying standard of 30 g/h for diesel engines
to be ``Clean Idle Certified''.\96\ We request comment on the need or
appropriateness of setting a federal idle standard for diesel engines.
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\96\ 13 CCR Sec. 1956.8 (6)(C)--Optional NOX idling
emission standard.
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As mentioned previously, heavy-duty gasoline engines are currently
subject to FTP testing, but not RMC testing. We request comment on
including additional test cycles that may encourage manufacturers to
improve the emissions performance of their heavy-duty gasoline engines
in operating conditions not covered by the FTP cycle. In particular, we
are considering proposing an RMC procedure to include the sustained
high speeds and high loads that often produce high HC and PM emissions.
We may also propose a low-load or idle cycle to address high CO from
gasoline engines under those conditions. CARB's low-load cycle was
designed to assess diesel engine aftertreatment systems under low-load
operation. We request comment on the need for a low-load or idle cycle
in general, and suitability of CARB's diesel-targeted low-load and
clean idle cycles for evaluating the emissions performance of heavy-
duty gasoline engines as well.
In addition to proposing changes to the test cycles, we are
considering updates to the engine mapping test procedure for heavy-duty
gasoline engines. The current test procedure, which is the same for all
engine sizes, is intended to generate a ``torque curve'' that
represents the peak torque at any specific engine speed point.\97\
Historically, that goal was easily achieved due to the simplicity of
the heavy-duty gasoline engine hardware and controls. Modern heavy-duty
gasoline engines are more complex, with interactive features such as
spark advance, fuel-air ratio, and variable valve timing that
temporarily alter torque levels to meet supplemental goals (e.g.,
torque management for transmissions shifts). These features can lead to
lower-than-peak torque levels with the current engine mapping
procedure. We are assessing a potential requirement that the torque
curve established during the mapping procedure must represent the
highest torque level possible for the test fuel. This could be achieved
by various approaches, including disabling temporary conditions or
operational states in the electronic controls during the mapping, or
using a different order of speed and load points (e.g., sweeping up,
down, or sampling at a speed point over a longer time to allow
stabilization) to generate peak values. We seek comment on the need to
update our current engine mapping procedure for gasoline engines.
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\97\ 40 CFR 1065.510.
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C. In-Use Emission Standards
Heavy-duty diesel engines are currently subject to Not-To-Exceed
(NTE) standards that are not limited to specific test cycles, which
means they can be evaluated during in-use operation. In-use data are
collected by manufacturers as described in Section III.F.3. The data is
then analyzed pursuant to 40 CFR 86.1370 and 40 CFR 86.1912 to generate
a set of engine-specific NTE events--that is, 30-second
[[Page 3322]]
intervals for which engine speeds and loads remain in the control area.
There is no specified test cycle for these standards; the express
purpose of the NTE test procedure is to apply the standard to engine
operation conditions that could reasonably be expected to be seen by
that engine in normal vehicle operation and use, including a wide range
of real ambient conditions.
EPA refers to the range of engine operation where the engine must
comply with the NTE standards as the ``NTE zone.'' The NTE zone
excludes operating points below 30% of maximum torque or below 30% of
maximum power. The NTE zone also excludes speeds below 15% of the
European Stationary Cycle speed. Finally, the NTE procedure also
excludes certain operation at high altitudes, high intake manifold
humidity, or at aftertreatment temperatures below 250[deg] C. Data
collected in-use is considered a valid NTE event if it occurs within
the NTE zone, lasts 30 seconds or longer, and does not occur during any
of the exclusion conditions mentioned previously (engine,
aftertreatment, or ambient).\98\
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\98\ For more on our NTE provisions, see 40 CFR 86.1362.
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NTE standards have been successful in broadening the types of
operation for which manufacturers design their emission controls to
remain effective. However, our analysis of existing in-use test data
indicates that less than five percent of a typical time-based dataset
are valid NTE events that are subject to the in-use NTE standards; the
remaining data are excluded. Furthermore, we found that emissions are
high during many of the excluded periods of operation, such as when the
aftertreatment temperature drops below the catalyst light-off
temperature. For example, 96 percent of tests from 2014, 2015, and 2016
in-use testing orders passed with NOX emissions for valid
NTE events well below the 0.3 g/hp-h NTE standard. When we used the
same data to calculate NOX emissions over all operation
measured, not limited to valid NTE events, the NOX emissions
were more than double (0.5 g/hp-h).\99\ The results were higher when we
analyzed the data to only consider NOX emissions that occur
during low load events. These results suggest there may be great
potential to improve in-use performance by considering more of the
engine operation when we evaluate in-use compliance.
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\99\ Hamady, Fakhri, Duncan, Alan. ``A Comprehensive Study of
Manufacturers In-Use Testing Data Collected from Heavy-Duty Diesel
Engines Using Portable Emissions Measurement System (PEMS)''. 29th
CRC Real World Emissions Workshop, March 10-13, 2019.
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The European Union ``Euro VI'' emission standards for heavy-duty
engines require in-use testing starting with model year 2014
engines.100 101 Manufacturers must check for ``in-service
conformity'' by operating their engines over a mix of urban, rural, and
freeway driving on prescribed routes using portable emission
measurement system (PEMS) equipment to measure emissions. Compliance is
determined using a work-based windows approach where emissions data are
evaluated over segments or ``windows.'' A window consists of
consecutive 1 Hz data points that are summed until the engine performs
an amount of work equivalent to the European transient engine test
cycle (World Harmonized Transient Cycle). EPA and others have compared
the performance of U.S.-certified engines and Euro VI-certified engines
and concluded that the European engines' NOX emissions are
comparable to U.S. 2010 standards-certified engines under city and
highway operation, but lower in light-load conditions.\102\ This
suggests that manufacturers respond to the Euro VI test procedures by
designing their emission controls to perform well over broader
operation. EPA intends the CTI to expand our in-use procedures to
capture nearly all real-world operation. We are considering an approach
similar to the European in-use program, with key distinctions that
improve upon the Euro VI approach, as discussed below.
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\100\ COMMISSION REGULATION (EU) No 582/2011, May 25, 2011.
Available online: https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:02011R0582-20180118&from=EN.
\101\ COMMISSION REGULATION (EU) 2018/932, June 29, 2018.
Available online: https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32018R0932&from=EN.
\102\ Rodriguez, F.; Posada, F. ``Future Heavy-Duty Emission
Standards An Opportunity for International Harmonization''. The
International Council on Clean Transportation. November 2019.
Available online: https://theicct.org/sites/default/files/publications/Future%20_HDV_standards_opportunity_20191125.pdf.
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Most importantly, we are not currently intending to propose
prescribed routes for our in-use compliance test program. Our current
program requires data to be collected in real-world operation and we
would consider it an unnecessary step backward to change that aspect of
the procedure. In what we believe to be an improvement to a work-based
window, we are considering a moving average window (MAW) approach
consisting of time-based windows. Instead of basing window size on an
amount of work, we are evaluating window sizes ranging from 180 to 300
seconds.\103\ The time-based windows would be intended to equally
weight each data point collected.
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\103\ Our evaluation includes weighing our current understanding
that shorter windows are more sensitive to measurement error and
longer windows make it difficult to distinguish between duty cycles.
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We also recognize that it would be difficult to develop a single
standard that would be appropriate to cover the entire range of
operation that heavy-duty engines experience. For example, a numerical
standard that would be technologically feasible under worst case
conditions such as idle, would necessarily be much higher than the
levels that are feasible when the aftertreatment is functioning
optimally. Thus, we are considering separate standards for distinct
modes of operation. Our current thinking is to group the second-by-
second in-use data into one of three bins using a ``normalized average
CO2 rate'' from the certification test cycles to identify
the boundaries.\104\ Data points with a normalized average
CO2 rate greater than 25 percent (equivalent to the average
power of the current FTP) could be classified as medium-/high-load
operation and binned together. We are considering two options for
identifying idle data points. The first option would use a vehicle
speed less than 1 mph. The second option would use the normalized
average CO2 rate of a low-load certification cycle.\105\ The
remaining data points, bounded by the idle and medium-/high-load bins,
would contribute to the low-load bin data.
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\104\ We plan to propose that ``normalized average
CO2 rate'' be defined as the mass of NOX (in
grams) divided by the mass of CO2 (in grams) and
converted to units of mass of NOX per unit of work by
multiplying by the work-specific CO2 emissions value. Our
current thinking is to use the work-specific CO2 value
reported to EPA as part of the engine's family certification level
(FCL) for the FTP certification cycle.
\105\ The low load cycle proposed by CARB has an average power
of eight percent.
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We are considering several approaches for evaluating the emissions
performance of the binned data. One approach would sum the total
NOX mass emissions divided by the sum of CO2 mass
emissions. This ``sum-over-sum'' approach would successfully account
for all NOX emissions; however, it would require the
measurement system (PEMS or a NOX sensor) to be accurate
across the complete range of emissions concentrations. We are also
considering the advantages and disadvantages other statistical
approaches that evaluate a high percentile of the data instead of the
full set. We request comment on all aspects
[[Page 3323]]
of a moving average window analysis approach. Commenters are encouraged
to share the benefits and limitations of the window sizes, binning
criteria, and performance calculations introduced here, as well as
other strategies EPA should consider. We also request data providing
time and cost estimates for implementing a MAW-based in-use program and
what aspects of this approach could be phased-in to reduce some of the
upfront burden.
As mentioned previously, we are considering a separate MAW-based
standard for each bin. In our current NTE-based program, the NTE
standards are 1.5 times the certification duty-cycle standards.
Similarly, for the MAW-based standards, we could design our
certification and in-use programs to include corresponding laboratory-
based cycles and in-use bins with emission standards that relate by a
scaling factor. Alternatively, a percentile-based performance
evaluation may make a scaling factor unnecessary. We request comment on
appropriate scaling factors or other approaches to setting MAW-based
standards. Finally, we request comment on whether there is a continued
need for measurement allowances in an in-use program such as described
above.
D. Extended Regulatory Useful Life
Under the Clean Air Act, an engine or vehicle's useful life is the
period for which the manufacturer must demonstrate, to receive EPA
certification, that the engine or vehicle will meet the applicable
emission standard, including accounting for deterioration over time.
Section 207(c) of the Act requires manufacturers to recall and repair
engines if ``a substantial number of any class or category'' of them
``do not conform to the regulations . . . when in actual use throughout
their useful life.'' Thus, there are two critical implications for the
length of the useful life: (1) It defines the emission durability the
manufacturer must demonstrate for certification, and (2) it is the
period for which the manufacturer is liable for compliance in-use. With
respect to the durability demonstration, manufacturers can either show
that the components will generally last the full useful life and retain
their function in meeting the applicable standard, or show that they
will be replaced at appropriate intervals by owners.
Section 202(d) of the Act directs EPA to ``prescribe regulations
under which the useful life of vehicles and engines shall be
determined'' and establishes minimum values of 10 years or 100,000
miles, whichever occurs first. The Act authorizes EPA to adopt longer
periods that we determine to be appropriate. Under this authority, we
have established the following useful life mileage values for heavy-
duty engines: \106\
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\106\ EPA adopted useful life values 110,000, 185,000, and
290,000 miles for light, medium, and heavy heavy-duty engines
(respectively) in 1983. (48 FR 52170, November 16, 1983). The useful
life for heavy heavy-duty engines was subsequently increased to
435,000 miles for 2004 and later model years. (62 FR 54694, October
21, 1997).
110,000 miles for gasoline-fueled and light heavy-duty diesel
engines
185,000 miles for medium heavy-duty diesel engines
435,000 miles for heavy heavy-duty diesel engines
Analysis of in-use mileage accumulation and typical rebuild
intervals shows that current regulatory useful life values are much
lower than actual in-use lifetimes of heavy-duty engines and vehicles.
In 2013, EPA commissioned an industry characterization report that
focused on heavy-duty diesel engine rebuilds.\107\ The report relied on
existing data from MacKay & Company surveys of heavy-duty vehicle
operators. An engine rebuild was categorized as either an in-frame
overhaul (where the rebuild occurred while the engine remained in the
vehicle) or as an out-of-frame overhaul (where the engine was removed
from the vehicle for somewhat more extensive service). We believe an
out-of-frame overhaul is a reasonable estimate of a heavy-duty engine's
primary operational life.\108\ The following average mileage values
were associated with out-of-frame overhauled engines from each of the
heavy-duty vehicle classes in the report:
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\107\ ICF International, ``Industry Characterization of Heavy
Duty Diesel Engine Rebuilds'' EPA Contract No. EP-C-12-011,
September 2013.
\108\ In-frame rebuilds tend to be less complete and occur at
somewhat lower mileages.
Class 3: 256,000 miles
Class 4: 346,300 miles
Class 5: 344,200 miles
Class 6: 407,700 miles
Class 7: 509,100 miles
Class 8: 909,900 miles
We translated these vehicle classes to EPA's regulatory classes for
engines assuming Classes 3, 4, and 5 represent light heavy-duty diesel
engines (LHDDEs), Classes 6 and 7 represent medium heavy-duty diesel
engines (MHDDEs) and Class 8 represents heavy heavy-duty diesel engines
(HHDDEs). The resulting average rebuild ages for LHDDE, MHDDE, and
HHDDE are 315,500; 458,400; and 909,900, respectively.\109\ The current
regulatory useful life of today's engines covers less than half of the
primary operational life of HHDDEs and MHDDEs and less than a third of
LHDDEs--assuming the engines are only overhauled one time. We welcome
comment on the average number of times an engine core receives an
overhaul before being scrapped. We are also requesting comment on the
whether the 2013 EPA report continues to reflect modern engine
rebuilding practices.
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\109\ Note that these mileage values reflect replacement of
engine components, but do not include aftertreatment components. At
the time of the report, the population of engines equipped with DPF
and SCR technologies was limited to relatively new engines that were
not candidates for rebuild.
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We see no reason to change the useful life values with respect to
years. However, based on available data, we intend to propose new
useful life mileage values for all categories of heavy-duty engines to
be more reflective of real-world usage. Although we are continuing to
analyze the issue, we may propose to base the new useful life values
for engines on the median or average period to the first rebuild,
measured as mileage at the first out-of-frame overhaul. The reason to
tie useful life to rebuild intervals stems from the changes to an
engine when it is rebuilt. Rebuilding involves disassembling
significant parts of the engine and replacing or remachining certain
combustion-related components.
We are also evaluating the useful life for gasoline engines.
Beginning no later than model year 2021, chassis-certified heavy-duty
gasoline vehicles are subject to a 150,000-mile useful life. We request
comment on whether this would be the appropriate value for heavy-duty
gasoline engines, or if a higher value would be more appropriate.
Consistent with Section III.A.2.i, we would expect to apply the same
useful life for evaporative emissions technologies.
A direct result of longer useful life values would be to require
manufacturers to change their durability demonstrations. Currently
manufacturers measure emissions from a representative engine as they
accumulate service hours on it. If we extend useful life with no other
changes to this approach, manufacturers would need to extend this
durability testing out further.\110\ We request comment on alternative
approaches that should be considered. For example, we could allow
manufacturers to base the durability demonstration on component
replacement if manufacturers could demonstrate that the component would
actually be replaced in use. EPA has previously stated that a
manufacturer's
[[Page 3324]]
commitment to perform the component replacement maintenance free of
charge may be considered adequate, depending on the component. See 40
CFR 86.004-25 and related sections for other examples of how a
manufacturer could potentially demonstrate durability.
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\110\ See Section III.F.4, which describes potential
opportunities to streamline our durability demonstration
requirements.
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In conversations with rebuilding facilities, it appears that
aftertreatment components typically remain with the vehicle when
engines are rebuilt out of frame and are not part of the rebuild
process. We request comment on the performance and longevity of the
aftertreatment components when the engine has reached the point of
requiring a rebuild. Currently, aftertreatment components are covered
by the useful life of the engine overall. While our current logic,
explained above, would not support proposing useful life values for the
entire engine that extend beyond the rebuild interval, it may not be
appropriate for the durability requirements for the aftertreatment to
be limited by the rebuild interval for the rest of the engine if
current aftertreatment systems remain in service much longer. Thus, we
are requesting comment on how to treat such components, including
whether there is a need for separate provisions for aftertreatment
components. One potential approach could be to establish a longer
useful life for such components. However, we are also considering the
possibility of requiring an a more extensive durability demonstration
for such parts. For example, this might include a more aggressive
accelerated aging protocol or an engineering analysis demonstrating a
greater resistance to catalyst deterioration.
Another approach could be to develop a methodology to incorporate
aftertreatment failure rates reflective of real-world experiences into
engine deterioration factors at the time of certification, using
methodology similar to incorporation of infrequent regeneration
adjustment factors (``IRAF''). In 2018, CARB published an Initial
Statement of Reasons document regarding proposed amendments to heavy-
duty maintenance and warranty requirements. This document includes
analysis of warranty data indicating that emission components for heavy
heavy-duty engines had failure rates ranging from 1-17 percent, while
medium heavy-duty engines had emission component failure rates ranging
from 0-37 percent.111 112 ARB did this analysis using data
from MY2012 engines, as this was the only model year with a complete
five-year history. That model year included the phase-in of advanced
emission controls systems, which may have an impact on failure rates
compared to other model years. EPA is seeking comment on whether these
rates reflect component failures for other model year engines and
information on representative failure rates for all model years.
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\111\ California Air Resources Board, ``Public Hearing to
Consider Proposed Amendments to California Emission Control System
Warranty Regulations and Maintenance Provisions for 2022 and
Subsequent Model Year On-road Heavy-Duty Diesel Vehicles and Heavy-
Duty Engines with Gross Vehicle Weight Ratings Greater Than 14,000
pounds and Heavy-Duty Diesel Engines in such Vehicles. Staff Report:
Initial Statement of Reasons'' May 2018. Available at: https://ww3.arb.ca.gov/regact/2018/hdwarranty18/isor.pdf.
\112\ California Air Resources Board, Appendix C: Economic
Impact Analysis/Assessment to the Heavy-Duty Warranty Initial
Statement of Reasons, page C-8. June 28, 2018. Available online:
https://ww3.arb.ca.gov/regact/2018/hdwarranty18/appc.pdf.
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E. Ensuring Long-Term In-Use Emissions Performance
As discussed above, deterioration of emission controls can increase
emissions from in-use vehicles. Such deterioration can be inherent to
the design and materials of the controls, the result of component
failures, or the result of mal-maintenance or tampering. We are
requesting comment on ways to reduce in-use deterioration of emissions
controls from all sources. We have identified five key areas of
potential focus and seek comment on the following topics:
Warranties that cover an appropriate fraction of engine
operational life
Improved, more tamper-resistant electronic controls
Serviceability improvements for vehicles and engines
Education and potential incentives
Engine rebuilding practices that ensure emission controls are
functional
We believe addressing these five areas could offer a comprehensive
strategy for ensuring in-use emissions performance over more of an
engine's operational life.\113\ The following sections describe
possible provisions we believe could especially benefit second or third
owners of future engines who, under the current structure, may not have
access to resources for maintaining compliance of their higher-mileage
engines.
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\113\ Memorandum to Docket EPA-HQ-OAR-2019-0055. ``Enhanced and
Alternative Strategies to Achieve Long-term Compliance for Heavy-
Duty Vehicles and Engines; the WISER Strategy'', Amy Kopin, December
12, 2019.
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1. Lengthened Emissions Warranty
Section 207(a) of the Clean Air Act requires manufacturers to
provide an emissions warranty. This warranty offers protection for
purchasers from costly repairs of emission controls during the warranty
period and generally covers all expenses related to diagnosing and
repairing or replacing emission-related components.\114\ EPA has
established by regulation the warranty periods for heavy-duty engines
to be whichever comes first of 5 years or 50,000 to 100,000 miles,
depending on engine size (see 40 CFR 86.085). However, due to the high
annual mileage accumulation of many trucks, our early assessment is
that the current warranty periods are insufficient for real-world
operations. For example, today's mileage requirements may represent
less than a single year's worth of coverage for some Class 8
vehicles.\115\ We welcome comment on annual vehicle miles travelled for
different classes and vocations.
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\114\ See 40 CFR 1068.115 and Appendix I to Part 1068 for a list
of covered emission-related components.
\115\ American Transportation Research Institute, ``An Analysis
of the Operational Costs of Trucking: 2017 Update'' October 2017.
Available here: https://truckingresearch.org/wp-content/uploads/2017/10/ATRI-Operational-Costs-of-Trucking-2017-10-2017.pdf.
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We intend to propose longer emissions warranty periods. A longer
emissions warranty period could provide an extended period of
protection for purchasers, as well as a greater incentive for
manufacturers to design emission control components that are more
durable and less costly to repair. Longer periods of protection for
purchasers could provide a greater incentive for owners to
appropriately maintain their engines and aftertreatment systems so as
not to void their warranty. Designing more durable components could
help reduce the potential for problems later in the vehicle life that
lead to breakdowns and recalls. For instance, in at least one recent
recall related to certain SCR catalysts in heavy-duty vehicles, the
recall was not announced until nearly nine years after the initial sale
of these engines; as such, there was a prolonged period of real-world
emissions increases, and some owners likely absorbed significant cost
and downtime for repairs that could have been covered by an extended
warranty.116 117 More
[[Page 3325]]
durable parts could also lead to fewer breakdowns, which would likely
reduce the desire for owners to tamper with emissions controls by
bypassing DPF or SCR systems. In addition, extended warranties would
result in additional tracking by OEMs of potential defect issues, which
would increase the likelihood that emission defects (such as those
involved in the recent recall) would be corrected in a timely manner.
We request comment on emission component durability, as well as
maintenance or operational strategies that could substantially extend
the life of emission components and any regulatory barriers to
implementing these strategies.
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\116\ U.S. Environmental Protection Agency. ``EPA Announces
Largest Voluntary Recall of Medium- and Heavy-Duty Trucks.'' July
31, 2018. Available online: https://www.epa.gov/newsreleases/epa-announces-largest-voluntary-recall-medium-and-heavy-duty-trucks.
\117\ Jaillet, James, ``Volvo setting aside $780M to address
emission system degradation problem'' January 4, 2019. Available
here: https://www.ccjdigital.com/volvo-setting-aside-780m-to-address-emissions-system-degradation-problem/ Accessed 10/2/19.
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By rule, manufacturers providing a basic mechanical warranty must
also cover emission related repairs for those same components.\118\
Most engine manufacturers offer a 250,000-mile base warranty on their
heavy heavy-duty engines, which already exceeds the current minimum
100,000-mile emission warranty requirement. We request comment on an
appropriate length of emissions warranty period for engine and
aftertreatment components to incentivize improved durability with
reasonable cost.
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\118\ See 40 CFR 86.004-2, definition of ``warranty period''.
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One mechanism to maintain lower costs for a longer emissions
warranty period could be to vary the length of warranty coverage across
different types of components. For example, certain components (e.g.,
aftertreatment components) could have a longer warranty period.
Commenters are encouraged to address whether warranty should be tied to
longer useful life, as well as whether the warranty period should vary
by component and/or engine category.
With traditional warranty structures, parts and labor are covered
100 percent throughout a limited warranty period. We welcome comments
addressing whether there would be value in alternative approaches.
Figure 2 below provides a high-level illustration of alternative
approaches to the traditional warranty structure. For example, there
could be longer, prorated warranties that provide different levels of
warranty coverage based on a vehicle's age or mileage. In addition, the
warranty could be limited to include only certain parts after a certain
amount of time, and/or not include labor for part, or even all, of the
duration of coverage. We are seeking comment on any combination of
these or other approaches. Commenters should consider discussing the
components that could be included under each approach, and an
appropriate period of time for given classes of vehicle and individual
components. Commenters are encouraged to consider this issue in the
context of the benefits of longer emissions warranty periods--namely
providing an extended period of protection for purchasers, as well as a
greater incentive for manufacturers to design emission control
components that are more durable and less costly to repair.
[GRAPHIC] [TIFF OMITTED] TP21JA20.039
2. Tamper-Resistant Electronic Controls
Although EPA lacks robust data on the frequency of tampering with
heavy-duty engines and vehicles, enforcement activities continue to
find evidence of tampering nationwide. Recently, EPA announced a new
National Compliance Initiative (``NCI'') that will include enhanced
collaboration with states to reduce the manufacture, sale, and
installation of defeat devices on vehicles and engines, with a focus on
commercial truck fleets.\119\
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\119\ Belser, Evan, ``Tampering and Aftermarket Defeat Devices''
Presented to the National Association of Clean Air Agencies.
September 18, 2019. Available here: http://www.4cleanair.org/sites/default/files/resources/EPA%20Presentation%20to%20NACAA%20re%20Tampering%20and%20Aftermarket%20Defeat%20Device%20Sept%202019.pdf.
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We have identified several different ways that tampering can
occur.\120\ Most commonly, the engine's emission system parts are
physically removed or ``deleted'' electronically through the use of
software which can disable these components. One of the key methods to
[[Page 3326]]
enable such actions is through tampering with the engine control module
(ECM) calibration.
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\120\ U.S. Environmental Protection Agency, ``Enforcement Data
and Results'', Available online: https://www.epa.gov/enforcement/enforcement-data-and-results. Accessed September 18, 2019.
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We are considering several approaches to prevent tampering with the
ECM. One approach could be for manufacturers to provide public access
to unique data channels that can be used by owners or enforcement
agencies to confirm emission controls are active and functioning
properly. A second approach to improved ECM security could be to
develop methodologies that flag when ECMs are flashed with improper
calibrations. This approach would require a process to distinguish
between authorized and unauthorized flashing events, detect an
unauthorized event, and store information documenting such events in
the ECM. Finally, we are following ongoing work at SAE International
that focuses on preventing cyber security hacking activity. The efforts
to combat such safety- and security-related concerns may provide a
pathway to apply similar solutions for emission control software and
modules. We anticipate such a long-term approach would require effort
beyond the CTI rulemaking timeframe. EPA requests comment on these or
other actions we could take to help prevent ECM tampering.
3. Serviceability Improvements
Vehicle owners play an important role in achieving the intended
emission reductions of the technologies that manufacturers implement to
meet EPA standards. Vehicle owners are expected to properly maintain
the engines, which includes scheduled (preventive) maintenance (e.g.,
maintaining adequate DEF supply for their diesel engines'
aftertreatment) and repairs when components or systems degrade or fail.
Although defective designs and tampering can contribute significantly
to increased in-use emissions, mal-maintenance (which includes improper
repairs, delayed repairs, and delayed or unperformed maintenance) also
increases in-use emissions. Mal-maintenance (by owners or repair
facilities) can result from:
High costs to diagnose and repair
Inadequate maintenance instructions
Limited access to service information and specialized tools to
make repairs
As discussed below, we are looking to improve in-use maintenance
practices by addressing these factors. We also discuss how maintenance
concerns can increase tampering.
We are especially interested in the repair and maintenance
practices of second owners, which are typically individual owners and
small fleets that do not have the sophisticated repair facilities of
the larger fleets. These second owners often experience emission-
related problems that cannot be diagnosed easily, causing the repairs
to be delayed. While fleets often have sufficient resources to obtain
engine manufacturer-specific diagnostic tools for their trucks and can
diagnose emission-systems problems quickly, smaller fleets or
individual owners may be required to tow their truck to a dealer to
diagnose and address the problem.
In 2009, EPA finalized regulations for the heavy-duty industry to
ensure that manufacturers make ``service information'' available to any
person repairing or servicing heavy-duty vehicles and engines (see 74
FR 8309, February 24, 2009). This service information includes:
Information necessary to make use of the OBD system, instructions for
making emission-related diagnoses and repairs, training information,
technical service bulletins, etc. EPA is considering whether the
service information and tools needed to diagnose problems with heavy-
duty emission control systems are available and affordable. EPA
requests comment on the following serviceability topics:
Usefulness of currently available emission diagnostic
information and equipment
The adequacy of emission-related training for diagnosis and
repair of these systems
The readiness and capabilities of repair facilities in making
repairs
The reasonableness of the cost of purchasing this information
and the equipment
The prevalence of using of this equipment outside of large
repair facilities
If there are any existing barriers to enabling owners to
quickly diagnose emission control system problems
We are currently evaluating which OBD signals are needed to
diagnose and repair emission control components. While SAE's J1939
protocol establishes a comprehensive list of signals and parameters
used in heavy-duty trucks, many signals are not required to be
broadcast publicly. Ensuring that all owners, including those who
operate older, higher-mileage vehicles, have access to service
information to properly diagnose problems with their truck's emission
system could reduce the cost for many owners who choose to do some
maintenance on their own. Although J1939 includes nearly 2,000
parameters OBD regulations dictate a limited number of signals must be
broadcast publicly. While today, some manufacturers broadcast more
signals than are required, there is no guarantee that this practice
will continue which could lead to loss of diagnostic ability.
Therefore, we request comment on which signals we should require to be
made available publicly to ensure adequate access to critical emissions
diagnostic information.
Maintenance issues can result in owner dissatisfaction, which can
incentivize removal or bypass of emission controls. EPA is aware of
significant discontent expressed by owners concerning their experiences
with emission systems on vehicles compliant with fully phased-in 2010
standards--in particular, for the first several model years after the
new standards went into effect. Although significant improvements have
been made to these systems since they were introduced into the market,
reliability issues continue to cause concern for owners. For example,
software and/or component failures can occur with little-to-no warning.
Misdiagnosis can also lead to repeated repairs that don't solve the
problem with the risk of repeated breakdowns, tows, and trips to repair
facilities. We believe that reducing maintenance issues could also
reduce tampering.
We are also evaluating the use of maintenance-inducing control
features (``inducements'') that degrade engine performance as a means
to ensure that certain critical maintenance steps are performed. For
example, SCR-equipped engines generally include features that
``derate'' or severely limit engine operation if a vehicle is operated
without DEF. EPA guidance for such features was issued in 2009.\121\
While inducements were designed to encourage owners to perform proper
maintenance, an inducement can be triggered for a variety of reasons
that an owner cannot control (e.g., faulty wiring, software glitches,
or sensor failures) and may not degrade emission control performance.
EPA understands that some owners view derate inducements as
particularly problematic when they are not due to improper maintenance,
because they are difficult to predict and may occur at inconvenient
locations, far from preferred repair facilities. Owners' prior concerns
over parts durability and potential breakdowns are likely heightened by
the risk of inducements. Given that we are nearing a decade of industry
experience in understanding
[[Page 3327]]
maintenance of SCR systems, we believe it is time to reevaluate these
features, and potentially allow for less severe inducements. We believe
such relief may also reduce tampering.
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\121\ U.S. Environmental Protection Agency. ``Certification
Requirements for Heavy-Duty Diesel Engines Using Selective Catalyst
Reduction (SCR) technologies'', February 18, 2009, CISD-09-04
(HDDE).
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We broadly request comment on actions EPA should take, if any, to
improve maintenance practices and the repair experience for owners. We
welcome comment on the adequacy of existing emission control system
maintenance instructions provided by OEMs. In addition, we request
comment on whether other stakeholders (such as state and local
agencies) may find it difficult in the field to detect tampering due to
limitations of available scan tools and limited publicly available
broadcast OBD parameters. We request comment on signals that are not
currently broadcast publicly that would enable agencies to ensure
vehicles are compliant during inspections.
4. Emission Controls Education and Incentives
In addition to more easily accessible service information for
users, we believe that there may also be educational programs and
voluntary incentives that could lead to better maintenance and real-
world emission benefits. We understand that there continues to be
misinformation in the marketplace regarding exhaust aftertreatment
systems, including predatory websites that incorrectly indicate that
their fuel economy-boosting delete kits are legal. We seek comment on
the potential benefits of educational and/or voluntary, incentive-based
programs such as EPA's SmartWay program.\122\ Such a program could
provide online training on issues such as the importance of the
emissions equipment, how it functions, how emissions systems impact
fuel economy, users' ability to access service information, and how to
identify legitimate methods and services that do not compromise their
vehicles' emissions compliance. In addition to educational elements, we
are seeking comment on whether and how to develop tools allowing fleets
to commit to selling used vehicles with fully functional and verified
emissions control systems.
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\122\ Learn about SmartWay. Available online at: https://www.epa.gov/smartway/learn-about-smartway. Accessed October 3, 2019.
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5. Improving Engine Rebuilding Practices 123
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\123\ As used here, the term ``rebuilding'' generally includes
practices known commercially as ``remanufacturing''. Under 40 CFR
part 1068, rebuilding refers to practices that fall short of
producing a ``new'' engine.
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Under 40 CFR 1068.120(b), EPA defines requirements for rebuilding
engines to avoid violating the tampering prohibition in 1068.101(b)(1).
EPA supports engine rebuilding that maintains emissions compliance, but
it is unclear if the rebuilding industry's current practices adequately
address the functioning of aftertreatment systems during this process.
We are interested in improving engine rebuilding practices to help
ensure emission controls continue to function properly after an engine
is rebuilt. In particular, we are concerned about components that
typically remain with the vehicle when the engine is removed for
rebuilding, especially aftertreatment components. Because these
components may not be included when an engine is overhauled, we believe
that additional provisions may be needed to help ensure that these
other components maintain proper function to the same degree that the
rebuilt components do.
There are practical limitations to implementing new regulations
that would include testing and repairing the aftertreatment system
during each rebuild event. Currently, engine rebuilding is focused on
the engine; aftertreatment systems may not be evaluated at the time of
rebuild--especially when it remains with the vehicle during an out-of-
frame rebuild. We recognize the potentially significant financial
undertaking that might be necessary for the rebuilding industry to
restructure their businesses to include aftertreatment systems in their
processes.
Instead, our goal of proposing new regulations for rebuilding would
be to ensure the aftertreatment system is functioning properly at the
time of rebuild. We are considering a program where rebuilders would
collect information documenting certain OBD codes to determine whether
their emission systems are on the truck and functioning prior to
placing an order for a factory-rebuilt engine or sending their engine
out for rebuilding. This could consist of the engine rebuilder
requesting that the owner provide them with a report showing the
results of a limited number of OBD parameters that indicate broadly the
status of the emissions systems. Such a program could involve the
rebuilder ensuring this report has been received, reviewed, and
retained. This sort of check would not be intended to impede the sale
of the rebuilt engine. We acknowledge that some engines may have
experienced catastrophic failures that may result in numerous ``check
engine'' codes and prevent owners or repair facilities from running
additional OBD monitors to confirm the aftertreatment system status.
We solicit comment on whether we could appropriately ensure
compliance without creating unnecessary market disruption by requiring
owners to attest that any problems shown in their engine's report will
be repaired within a certain timeframe. We believe this documentation
requirement would introduce a level of accountability with respect to
aftertreatment systems when engines are rebuilt, with minimal burden on
the rebuilders and owners. We request comment on the feasibility and
challenges of such an approach, including suggestions of relevant OBD
parameters, report format, and how to collect the information (e.g.,
could manufacturers build into new vehicles the ability for such a
status report to be run using a generic scan tool and be output in a
text file).
F. Certification and Compliance Streamlining
The fundamental requirements for certification of heavy-duty
engines are specified by the Clean Air Act. For example, the Act
provides:
Manufacturers must obtain a certificate of conformity from EPA
before introducing an engine into commerce
Manufacturers must obtain new certificates each year
The certificate must be based on test data
The manufacturer must provide an emissions warranty to the
purchaser
However, EPA has significant discretion for many aspects of our
certification and compliance programs, and we are requesting comment on
potential opportunities to streamline our requirements, while ensuring
no change in protection for public health and the environment,
including EPA's ability to ensure compliance with the requirements of
the CAA and our regulations. Commenters are encouraged to consider not
just potential cost savings associated with each aspect of
streamlining, but also ways to prevent any adverse impacts on the
effectiveness of our certification and in-use compliance program.
1. Certification of Carry-Over Engines
Our regulations currently require engine families to undergo a
thorough certification process each year. This includes ``carry-over''
engines with no year-to-year calibration or hardware changes. Although
we have already adopted certain simplifications, we intend to consider
additional
[[Page 3328]]
improvements to this this process under the CTI to reduce the burden of
certification for carry-over engines. We request comment on specific
revisions that could apply for certifying carry-over engines.
2. Modernizing of Heavy-Duty Engine Regulations
Heavy-duty engine criteria pollutant standards and related
regulations were codified into 40 CFR part 86 in the 1980s. We believe
the CTI provides an opportunity to clarify (and otherwise improve) the
wording of our existing heavy-duty criteria pollutant regulations in
plain language and migrate them to part 1036. This part, which was
created for the Phase 1 GHG program, provides a consistent, modern
format for our regulations, with improved organization. This migration
would not be intended to make any change to the compliance program,
except as specifically and expressly addressed in the CTI rulemaking.
We request comment on the benefits and concerns with this undertaking.
3. Heavy-Duty In-Use Testing Program
Under the current manufacturer-run heavy-duty in-use testing
program, EPA annually selects engine families to evaluate whether
engines are meeting current emissions standards. Once we submit a test
order to the manufacturer to initiate testing, it must contact
customers to recruit vehicles that use an engine from the selected
engine family. The manufacturer generally selects five unique vehicles
that have a good maintenance history, no malfunction indicators on, and
are within the engine's regulatory useful life for the requested engine
family. The tests require use of portable emissions measurement systems
(PEMS) that meet the requirements of 40 CFR 1065 subpart J.
Manufacturers collect data from the selected vehicles over the course
of a day while they are used for their normal work and operated by a
regular driver, and then submit the data to EPA.
EPA's current process for selecting an engine family test order is
undefined and can be based on a range of factors including, but not
limited to, recent compliance performance or simply length of time
since last data collection on that family. Onboard NOX
sensors present an opportunity to better define EPA's criteria for test
orders. For example, onboard NOX data could be used to
screen in-use engines for key performance characteristics that may
indicate a problem. We welcome comment on possible strategies and
challenges to incorporating onboard NOX sensor data in EPA's
engine family test order process.
An evolution of our current PEMS-based in-use testing approach
could be to use onboard NOX sensors that are already on
vehicles instead of (or potentially in addition to) PEMS as the
emission measurement tool for in-use compliance. In this scenario,
manufacturers would collect and store performance data on the engine's
computer until it is retrieved. When a test order is sent,
manufacturers could simply collect the stored data and send it to EPA,
reducing the burden of today's PEMS-based collection procedures. This
simplified data collection could potentially expand the pool of
vehicles evaluated for a given test order and compliance could be based
on a much greater percentage of the in-use fleet with broader coverage
of the industry's diverse operation. We are currently in the early
stages of evaluating key questions for this type of evolution in
approach to in-use testing. These key issues include: NOX
sensor performance (noted in III.A.3), appropriate engine parameters to
target, quantity of data to collect, performance metrics to calculate,
and frequency of reporting. Additionally, we are evaluating several
candidate processes for aggregating the results. See Section III.C for
a discussion of our early thinking on these topics as they relate to
potential updates to EPA's manufacturer-run in-use testing program.
Another aspect of this potential evolution in the in-use testing
program could be combining the use of onboard sensors with telematic
communication technologies that facilitate manufacturers receiving and
sending information from/to the vehicle in real time. Telematics
services are already increasingly used by the industry due to the
Department of Transportation's Federal Motor Carrier Safety
Administration's Electronic Logging Device (ELD) Rule that requires the
use of ELDs by the end of 2019.\124\ The value of being able to measure
NOX emissions from the in-use fleet could be increased if
coupled with real-time communication between the engine manufacturers
and the vehicles. For example, such a combination could enable
manufacturers to identify emission problems early. By being able to
schedule repairs proactively or otherwise respond promptly, operators
would be able to prevent or mitigate failures during in-use operation
and make arrangements to avoid disrupting operations. We request
comment on the potential use of telematics and communication technology
in ensuring in-use emissions compliance.
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\124\ DOT Federal Motor Carrier Safety Administration. ``ELD
Factsheet,'' Available online: https://www.fmcsa.dot.gov/hours-service/elds/eld-fact-sheet-english-version.
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Finally, we request comment on the need to measure PM emissions
during in-use testing of DPF-equipped engines--whether under the
current regulations or under some future program. PEMS measurement is
more complicated and time-consuming for PM measurements than for
gaseous pollutants such as NOX and eliminating it for some
or all in-use testing would provide significant cost savings.
Commenters are encouraged to address whether there are less expensive
alternatives for ensuring that engines meet the PM standards in use.
4. Durability Testing
Pursuant to Clean Air Act Section 206, EPA's regulations require
that a manufacturer's application for certification include a
demonstration that the new engines will meet applicable emission
standards throughout the engines' useful life. This is often called the
durability demonstration. The core of this demonstration includes
procedures to calculate a deterioration factor (DF) to project full
useful life emissions compliance based on testing a low-hour
engine.\125\
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\125\ 40 CFR 86.1823-08.
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A deterioration factor can be determined directly for heavy-duty
diesel engines by aging the engine and exhaust aftertreatment system to
full useful life on an engine dynamometer. This time-consuming process
requires manufacturers to commit to product configurations well ahead
of their pre-production certification testing in order to ensure the
durability testing is complete. Some manufacturers run multiple,
staggered durability tests in parallel in case a component failure
occurs that would require a complete restart of the aging process.
Recognizing that full useful life testing is a significant
undertaking (that can involve more than one full year of continuous
engine operation for heavy heavy-duty engines), EPA has allowed
manufacturers to age their systems to between 35 and 50 percent of full
useful life on an engine dynamometer and extrapolate the data to full
useful life. This extrapolation reduces the time to complete the aging
process, but it is unclear if it accurately captures the emissions
deterioration of the system.
[[Page 3329]]
i. Diesel Aftertreatment Rapid Aging Protocol
The current durability demonstration provisions were developed
before aftertreatment systems were widely adopted for emission control
and we believe some of the inaccuracy of the deterioration
extrapolation may be due to the deterioration mechanisms unique to
catalysts. We believe a more cost-efficient demonstration protocol
could focus on the emissions-critical catalytic aftertreatment system
to accelerate the process and possibly improve accuracy.
EPA is developing a protocol for demonstrating aftertreatment
durability through an accelerated catalyst aging procedure. The
objective of this protocol is to artificially recreate the three
primary catalytic deterioration processes observed in field-aged
components: Thermal aging based on time at high temperature, chemical
aging that accounts for poisoning due to fuel and oil contamination,
and deposits. This work to develop a diesel aftertreatment rapid-aging
protocol (DARAP) builds on an existing rapid-aging protocol designed
for light-duty gasoline vehicles (64 FR 23906).
A necessary feature of this protocol development would be a process
to validate deterioration projections from accelerated aging. Three
engines and their corresponding aftertreatment systems will be aged
using our current, engine-focused durability test procedure. Three
comparable aftertreatment systems will be aged using a burner in place
of an engine. We are planning to evaluate emissions using this
accelerated approach, compared to the standard approach, at the
following approximate intervals: 0; 280,000; 425,000; 640,000; and
850,000 miles.
We anticipate this validation program will take six months per
engine platform. We expect the program will be completed after the CTI
NPRM is issued. We plan to have results from one of the test engines in
time to consider when developing the proposal, with the remaining
results and final report completed before the final rulemaking. We
request comment on the need, usefulness and appropriateness for a
diesel aftertreatment rapid-aging protocol, and we request comment on
the test program EPA has initiated to inform the accelerated durability
demonstration method outlined here.
ii. Durability Certification
As mentioned previously, EPA has issued guidance to ensure
manufacturers report accurate deterioration factors. EPA is considering
updates to the durability demonstration currently required for
manufacturers, which may still require manufacturers to validate their
reported values. We believe onboard data collected for in-use
compliance could provide a pathway for manufacturers to show the
deterioration performance of their engines in the real world with
reduced need for upfront durability demonstrations. We request comment
on the suitability of onboard data to supplement our current or future
deterioration factor demonstrations, as well as opportunities to reduce
testing burden by reporting in-use data.
G. Incentives for Early Emission Reductions
The Clean Air Act requires that EPA provide manufacturers
sufficient lead time to meet new standards. However, we recognize that
manufacturers may have opportunities to introduce some technologies
earlier than required, and that public health and the environment could
benefit from such early introduction. Thus, we are requesting comments
on potential provisions that would provide a regulatory incentive for
reducing emissions earlier than required, including but not limited to
incentives for low-emission, advanced powertrain technologies.\126\
Such approaches can have the effect of accelerating the turnover of the
existing fleet of heavy-duty vehicles to lower-emitting vehicles.
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\126\ See Section III.A.4 for more discussion on advanced
powertrain technologies.
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We have often relied on emission credit banking provisions, such as
those in 40 CFR 1036.715, to incentivize early emission reductions.
This approach has worked well for rulemakings that set numerically
lower standards but keep the same test cycles and other procedures.
However, this would not necessarily be the case for the CTI, where we
expect to adopt new test cycles or other fundamentally new approaches.
Manufacturers could generate and bank emission credits for the two
current EPA test cycles (the FTP and RMC) in the near-term, but it is
unclear how those credits could be used to show compliance with respect
to operating modes that are not reflected in the current cycles.
Manufacturers could certify to any new CTI provisions once the rule
is finalized, but that may not leave sufficient time for manufacturers
to complete all of the steps required to certify new engines early. For
example, manufacturers would not know the new useful life mileages
until the rule is finalized, which may hinder them from completing
durability work early. Therefore, we request comment on alternative
approaches to incentivize early emission reductions.
In particular, we would be interested in the early adoption of
technology that reduces low-load emissions. One approach we are
considering would be for manufacturers to certify engines with new
technology to the existing requirements (i.e., FTP and RMC test cycles
and durability demonstration), but then track the engines in-use using
improved in-use provisions. This approach could demonstrate that the
engines have lower emissions in use than other engines (including low-
load operation) and serve as a pilot program for an updated in-use
program. We request comment on options to potentially generate
numerical off-cycle credit under this approach, or other interim
benefits, such as delayed compliance for some other engine family, that
could incentivize early emissions reductions.
IV. Next Steps
As described above, EPA has made important progress in the
development of technical information to support new, more stringent
NOX emission standards and other potential program elements.
We also expect to receive additional technical information in the
comments on this ANPR. We intend to publish a NPRM this year, after
reviewing the comments and considering how any new information we
receive may be used in the analysis we have underway to support the CTI
NPRM.
See the PUBLIC PARTICIPATION section at the beginning of this
notice for details on how to submit comments.
V. Statutory and Executive Order Reviews
Under Executive Order 12866, entitled Regulatory Planning and
Review (58 FR 51735, October 4, 1993), this is not a ``significant
regulatory action.'' Because this action does not propose or impose any
requirements, the various statutes and Executive Orders that apply to
rulemaking do not apply in this case. Should EPA subsequently pursue a
rulemaking, EPA will address the statutes and Executive Orders as
applicable to that rulemaking. Nevertheless, the Agency welcomes
comments and/or information that would help the Agency to assess any of
the following:
The potential impact of a rule on small entities pursuant
to the Regulatory Flexibility Act (RFA) (5 U.S.C. 601 et seq.);
Potential impacts on federal, state, or local governments
pursuant to the Unfunded Mandates Reform Act (UMRA) (2 U.S.C. 1531-
1538);
[[Page 3330]]
Federalism implications pursuant to Executive Order 13132,
entitled Federalism (64 FR 43255, November 2, 1999);
Availability of voluntary consensus standards pursuant to
section 12(d) of the National Technology Transfer and Advancement Act
of 1995 (NTTAA), Public Law 104-113;
Tribal implications pursuant to Executive Order 13175,
entitled Consultation and Coordination with Indian Tribal Governments
(65 FR 67249, November 6, 2000);
Environmental health or safety effects on children
pursuant to Executive Order 13045, entitled Protection of Children from
Environmental Health Risks and Safety Risks (62 FR 19885, April 23,
1997)--applies to regulatory actions that: (1) Concern environmental
health or safety risks that EPA has reason to believe may
disproportionately affect children and (2) are economically significant
regulatory action, as defined by Executive Order 12866;
Energy effects pursuant to Executive Order 13211, entitled
Actions Concerning Regulations that Significantly Affect Energy Supply,
Distribution, or Use (66 FR 28355, May 22, 2001);
Paperwork burdens pursuant to the Paperwork Reduction Act
(PRA) (44 U.S.C. 3501); or
Human health or environmental effects on minority or low-
income populations pursuant to Executive Order 12898, entitled Federal
Actions to Address Environmental Justice in Minority Populations and
Low-Income Populations (59 FR 7629, February 16, 1994).
The Agency will consider such comments during the development of
any subsequent proposed rulemaking.
Dated: January 6, 2020.
Andrew R. Wheeler,
Administrator.
[FR Doc. 2020-00542 Filed 1-17-20; 8:45 am]
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