Greenhouse Gas and Energy
Consumption Rates for On-road Vehicles:
Updates for MOVES2014
&EPA
United States
Environmental Protection
Agency
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Greenhouse Gas and Energy
Consumption Rates for On-road Vehicles:
Updates for MOVES2014
Assessment and Standards Division
Office of Transportation and Air Quality
U.S. Environmental Protection Agency
NOTICE
This technical report does not necessarily represent final EPA decisions or
positions. It is intended to present technical analysis of issues using data
that are currently available. The purpose in the release of such reports is to
facilitate the exchange of technical information and to inform the public of
technical developments.
&EPA
United States
Environmental Protection
Agency
EPA-420-R-15-003
October 2015
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Contents
1 Introduction 2
2 Energy Rate Updates 3
2.1 Light Duty Vehicles 3
2.1.1 Summary of Light-Duty Running Energy Rates 5
2.1.2 Summary of Light-Duty Start Energy Rates 7
2.2 Heavy-Duty Vehicles 8
3 Methane Emission Rates 10
3.1 Gasoline-fueled Vehicles 10
3.2 E85-fueled Vehicles 12
3.3 Diesel-fueled Vehicles 13
3.4 Compressed Natural Gas-fueled Transit Buses 14
4 Nitrous Oxide Emission Rates 15
4.1 Gasoline and Diesel-Fueled Vehicles 15
4.2 Alternative-Fueled Vehicles 19
5 Carbon Dioxide (CCh) Emission Rates 20
5.1 Carbon Dioxide Calculations 20
5.2 Carbon Dioxide Equivalent Emissions 21
6 Fuel Consumption Calculations 22
7 Appendix A. Timeline of Energy and GHG emissions in MOVES 23
8 Appendix B: Emission Control Technology Phase-In used for N2O Emission Rate
Calculations 25
9 References 30
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1 Introduction
The goal of this report is to provide a reference to the energy and greenhouse gas values that are
used in MOVES2014. This report presents the energy rates, nitrous oxide emission rates, and
methane fractions stored in the MOVES2014 database in tables and graphs. Rather than a
comprehensive documentation of the energy and emission rates, this reports provides
documentation only of the updates made to the rates for MOVES2014. A timeline of the
development of the energy and greenhouse gas emission rates in MOVES is presented in
Appendix A.
This report is divided into five major sections:
1. Energy Rates Updates
2. Methane (CH/t) Emission Rates
3. Nitrous Oxide (N2O) Emission Rates
4. Carbon Dioxide (CO2) Emission Rates
5. Fuel Consumption Calculations
MOVES2014 incorporates the light-duty greenhouse gas (GHG) emission standards affecting
model years 2017 and later cars and light trucks.l MOVES2014 also incorporates the heavy-
duty GHG Phase 1 emissions standards for model years 2014 and later.2 The energy rates for
light-duty vehicles are based on work conducted in MOVES2004,3 however, they have been
significantly updated in subsequent versions of MOVES, including MOVES2009, MOVES2010,
MOVES2010a,4 and MOVES2014. The intent of this report is to document the changes in
energy rates that were made between MOVES2010a and MOVES2014. We point the reader to
the earlier reports that document the development of the energy rates prior to MOVES2010a.3'4
In this report, we briefly discuss the impact of the HD GHG Phase 1 standards implemented in
MOVES2014. However, the details of the energy rates for heavy-duty are documented in the
MOVES2014 heavy-duty emissions rates report.5
The methane emission rates used in MOVES2014 are based on analysis done for MOVES2004.
As for the energy rates, we do not provide a comprehensive derivation of the original methane
rates. However, we document the updates made to convert these rates into the methane/THC
fractions used in MOVES2014, and we display example ratios.
The MOVES nitrous oxide emission rates have not been updated since MOVES2010. However,
this report provides summary tables and figures to provide greater detail and clarify their original
derivation.
MOVES calculates carbon dioxide (CO2) emissions using the energy emission rates. The values
used to convert energy to carbon dioxide emissions are presented here, along with the equation
and values used to calculate carbon dioxide equivalent emission rates.
Last, we present the values that MOVES uses to calculate fuel consumption in volume (gallons).
MOVES currently reports fuel usage in terms of energy (e.g KiloJoules), but does calculate
gallons for use in internal calculators. The values are presented in this report, so that users can
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calculate fuel volumes using MOVES output in a manner consistent with the MOVES
calculators.
2 Energy Rate Updates
2.1 Light Duty Vehicles
In MOVES2014, the energy rates for motorcycles (MC) are unchanged from MOVES2010a, as
well as energy rates from 2007 and earlier model year light-duty vehicles (LDV) and light-duty
trucks (LOT). In MOVES2010a, the energy rates for MC, LDV and LOT were consolidated
across weight classes and engine technologies, as discussed in the MOVES2010a energy updates
report.4 Earlier MOVES versions contained significantly more detail in the energy rates, which
varied by engine technologies, engine size and more refined loaded weight classes. For
MOVES2010a, the energy rates were simplified to be single energy rates for each regulatory
class, fuel type and model year combination. This was done by removing advanced technology
energy rates, and aggregating the MOVES2010 energy rates across engine size and vehicle
weight classes according to the default population in the MOVES2010 sample vehicle population
table. Because this approach uses highly detailed energy consumption data, coupled with
information on engine size and vehicle weight for the vehicle fleet that varies for each model
year, year-by-year variability was introduced into the aggregated energy rates used in
MOVES2010a and now in MOVES2014, as shown in Figure 2-2,
We revisited the MY 2008-MY2016 rates that had been updated for MOVES2010a, and changed
the ratio of reduction applied to the base rates between start and running. Many of the
compliance technologies anticipated to be used in response to the light duty greenhouse gas
regulation (transmission improvements, aerodynamic improvements, tires, etc) will not improve
performance during vehicle start. Thus the MOVES2010a method, which applied the same rate
of reduction to both running and starts, likely underestimated energy consumption from starts.
For MOVES2014, the reduction applied to starts was revised to be half of that applied to
running. Because energy consumption at start is a small fraction of the total, this increase has
little impact on total CO2 emissions; however to keep the composite emissions the same, we also
decreased fuel consumption for running emissions by about one percent.
EPA's Light Duty GHG MY 2017+ rule1 phases in for passenger cars, light-duty trucks, and
medium-duty passenger vehicles in MYs 2017 through 2025. After MY 2025, the standards
continue indefinitely. The final standards are projected to result in an average industry fleet-
wide level of 163 grams/mile of carbon dioxide (CO2) in model year 2025, which is equivalent to
54.5 miles per gallon (MPG) if achieved exclusively through fuel economy improvements.
For MOVES 2014, we adjusted the projected CO2 g/mile rates from the rulemaking regulatory
classes (car/truck) to the regulatory classes in MOVES (regClassID 20/30), removed the air
conditioning leakage improvements and left the air conditioning efficiency improvements in the
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rates themselves51. We also adjusted the emission rates for the on-road fuel economy gap of
approximately 20% (multiplying the CO2 rates by 1.25x).
We calculated ratios needed to produce the emission rates projected in the LD GHG rulemaking,
and then used these ratios to reduce the MY 2016 MOVES2010a base emission rates as shown in
Table 2-1 The trend in the energy emissions rates can be observed in Figure 2-2 and Figure 2-4.
Table 2-1 - Overall reductions as compared to MY LDV and LPT energy rates 2016 rates
MY
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031-
2050
Model year
GroupID
37
38
39
40
41
42
43
44
45
46
47
48
49
50
9
LDV
(RegClassID
20)
CO2 g/mile
269
258
247
236
226
217
207
198
190
190
190
190
190
190
190
LDV 20
Ratio
93%
89%
86%
82%
79%
75%
72%
69%
66%
66%
66%
66%
66%
66%
66%
LOT
(RegClassID
30)
CO2 g/mile
348
340
332
324
304
290
276
262
250
250
250
250
250
250
250
LOT ratio
97%
95%
93%
90%
85%
81%
77%
73%
70%
70%
70%
70%
70%
70%
70%
In MOVES2014, we made a number of additional minor updates to MOVES database tables.
These included updating the pollutantprocessmodelyear table to include references to new model
year (MY) groups for MY 2020 and later. This table now includes MY groups for each model
year from 2020 to 2030 and a new MY group for all MY 2031-2050 vehicles. We also updated
the energy emission rates for ethanol (E-85) and electricity, such that they continue to have
equivalent energy consumption as gasoline vehicles. Although the energy rates are the same for
these alternative fuels, the carbon content is different, resulting in different CO2 emission rates as
discussed in Section 5.1.
a Instead of adjusting MOVES multiplicative air conditioning adjustments, we lowered the overall running energy
emission rate to reflect the air conditioning improvements. The impact on emissions is equivalent.
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2.1.1 Summary of Light-Duty Running Energy Rates
Figure 2-1 plots the MOVES2014 running energy rates by operating mode for motorcycles
(MC), light-duty vehicles (LDV), and light-duty trucks (LDT) for model year 2012. For gasoline
LDVs the relative trend between energy rates and operating modes is constant starting in 1999
model year going forward. For gasoline LDT, the relative trend between energy rates and
operating modes is constant starting in MY 2001 going forward to MY 2050. However, as shown
in Figure 2-2, the magnitude of LDV and LDT gasoline energy consumption rates decrease
sharply beginning in MY 2012. As discussed earlier, E-85 vehicles and electric vehicles use the
same energy rates as gasoline vehicles.
Diesel LDV and LDT vehicles, starting in model year 2012, have the same relative energy rate
(for start and running) and operating mode trend as the corresponding MY gasoline vehicles. The
diesel energy rates are 2.9% lower than the gasoline running energy rates. The 2.9% difference
accounts for the higher carbon content in diesel fuel (Table 5-1) compared to gasoline fuel, such
that the CO2 emission rates are equivalent for 2012 MY+ gasoline and diesel vehicles. As shown
in Figure 2-2, the magnitude of LOG and LDT diesel energy consumption rates decrease at the
same rate as gasoline vehicles beginning in MY 2012.
The motorcycle running energy rates have the same relative shape between operating mode bins
starting in MY 1999 through MY 2050 as shown in Figure 2-1. The energy rates were developed
initially for MOVES20043 for three weight categories (<500 Ibs, 500-700 Ibs, and >700 Ibs), and
three engine size categories (<170 cc, 170-280 cc, and > 280 cc). When the energy rates were
consolidated to a single energy rate for all motorcycles in MOVES2010a4, this resulted in an
average increase in energy motorcycle rates between MY 1991 and MY 2000 due an
accompanying shift to larger motorcycles6, which is shown in Figure 2-2. We assumed the same
distributions of motorcycles starting in MY 2000 going forward to MY 2050 (2.9% <170cc,
4.3% 170-280cc, and 92.8%>280 cc, with 30% between 500-700 Ibs, and 70% > 700 Ibs). Thus
there are constant motorcycle energy running rates starting in MY 2000 to MY 2050.
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Figure 2-1. Running energy rates by operating mode (opModelD) for motorcycles (MC), light-duty vehicles
(LDV) and light-duty trucks (LDT) for model year 2012.
4e+05-
liJ2e+05-
Oe+00-
0 1 111213141516212223242527282930333537383940
opModelD
fuelTypeDesc -*- Diesel Fuel -"- Gasoline
Figure 2-2. Average energy consumption rates for motorcycle, light-duty vehicles, and light-duty trucks
across all running operating modes. 1960-1969 MY have the same energy consumption rates as MY 1970, and
the MY 2031-2050 have the same energy rates as MY 2030
:8e+05-
o
€
_£
* 6e+05-
g4e+05-
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2.1.2 Summary of Light-Duty Start Energy Rates
Figure 2-3 displays the energy rates for starts by operating mode for MY 2012 motorcycles,
light-duty vehicles, and light-duty trucks. As shown start energy increases for operating modes
with longer soak times as defined in Table 2-2. These fractions are used for all model years and
fuel types of light-duty vehicles. Additionally, the start energy rates are adjusted in MOVES for
increased fuel consumption required to start a vehicle at cold ambient temperatures. The
temperature effects are documented in the 2004 Energy Report.3
Figure 2-3. Start energy rates by operating mode (opModelD) for motorcycles (MC), light-duty vehicles
(LDV) and light-duty trucks (LDT) for model year 2012.
2000-
1000
£1 1000
ta
—) 500
i
n-
0)
2000
o
vi 1000
CO
f o
>,3000 -
O)
a) 2000
1000
o-
,
1
,
• '
\
\
1
1
1
\
\
,
1
I
I
'
;
i
i
^
o
• 1
i
h
1
P
101 102 103 104 105
opModelD
106 107
108
fuelTypeDesc -•- Diesel Fuel -•- Gasoline
Table 2-2. Fraction of energy consumed at start of varying soak lengths compared to the energy consumed at
a full cold start (operating mode 108).
Operating
Mode
101
102
103
104
105
106
107
108
Description
Soak Time < 6 minutes
6 minutes <= Soak Time < 30 minutes
30 minutes <= Soak Time < 60 minutes
60 minutes <= Soak Time < 90 minutes
90 minutes <= Soak Time < 120 minutes
120 minutes <= Soak Time < 360 minutes
360 minutes <= Soak Time < 720 minutes
720 minutes <= Soak Time
Fraction of energy
consumption
compared to cold
start
0.013
0.0773
0.1903
0.3118
0.4078
0.5786
0.8751
1
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Figure 2-4 depicts the energy start rates for a cold start (opModelOS) across model years for
light-duty vehicles. Motorcycles have a sharp decrease in energy starts in 1991 because MOVES
assumes 'controlled' energy starts starting with MY 1991 as documented in the MOVES2004
energy report3. The start rates for LDV and LDT have a large decrease starting in MY 2012 that
follows the same trend as the running rates.
Figure 2-4. Cold start energy rates (opMode 108) for motorcycle, light-duty vehicles, and light-duty trucks
6000-
-c
i
-3
_i
n>"
4000-
o
E
^2000-
LU
o-
1970
1990
2010
20301970
1990 2010
modelYearlD
20301970
1990
2010
2030
fuelTypeDesc -*- Diesel Fuel -*- Gasoline
2.2 Heavy-Duty Vehicles
The HD GHG Phase 1 standards2 began with the 2014 model year and increase in stringency
through 2018. The standards continue indefinitely after 2018. The program divides the diverse
truck sector into 3 distinct categories:
• Line haul tractors (largest heavy-duty tractors used to pull trailers, i.e. semi-trucks)
• Heavy-duty pickups and vans (3/4 and 1 ton trucks and vans)
• Vocational trucks (buses, refuse trucks, concrete mixers, etc)
The program set separate standards for engines and vehicles, and set separate standards for fuel
consumption, CO2, N2O, CH4 and HFCs.b
In MOVES2014, the HD GHG Phase 1 rule is implemented through three key elements. These
include (a) Revised running emission rates for total energy, (b) New aerodynamic coefficients
and weights, (c) Auxiliary Power Units (APUs) largely replace extended idle in long haul trucks
and are added as a new process. The revised running emissions rates for total energy and
auxiliary energy and criteria emission rates are documented in the MOVES2014 heavy-duty
' HFCs are not modeled in MOVES, and the N2O and CH4 standards are not considered forcing on emissions.
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emissions rates report.5 The revised aerodynamic coefficients for MY 2014 and later heavy-duty
trucks are documented in the MOVES2014 Population and Activity Report.7
In addition to the energy updates made in response to the HD GHG Phase 1 rule, we updated the
CNG transit bus energy rates based on data from CNG-transit bus driving cycle measurements as
documented in the MOVES2014 heavy-duty emissions report,5 and updated the energy starts to
be equivalent to diesel-fueled Urban Bus regulatory class. Likewise, the CNG transit buses are
subject to the same relative HD GHG Phase 1 energy reductions as the diesel Urban Bus
regulatory class.
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3 Methane Emission Rates
Methane emissions in MOVES2014 are unchanged from those in MOVES2010a. These
rates are based on those developed for MOVES2010, but in MOVES2010a (as
documented in the Updates to the MOVES2010a report4) we revised the algorithm used
to calculate the emissions such that methane emissions are a function of total
hydrocarbon (THC) and calculated appropriate ratios from the MOVES2010 rates.
MOVES2010 used a running emission rate (in terms of grams/mile, and a start emission
rate (in terms of grams/start) derived using emission test results from the Federal Test
Procedure, and supplemental results from the Inventory of U.S. Greenhouse Gas
Emissions and Sinks: 1990-2006.19 These rates had only one operating mode for running
and start conditions and did not vary according to ambient temperature or increase with
age to account for deterioration. This was in contrast to rates for total hydrocarbons
(THC) for which running emissions are calculated for each of 23 operating modes (based
on vehicle speed and power) and for which start emissions are calculated for each of 8
operating modes (based on vehicle soak time prior to engine start). In addition, the start
THC rates varied according to ambient temperature, and increased with age to account
for deterioration.
In MOVES2010a, the MOVES calculations to derive methane (CH/t) from the total hydrocarbons
(THC) values were revised to be calculated as a fraction of total hydrocarbons (THC)8. This
change more closely aligned the methane calculations with the calculation of other hydrocarbon
compounds in MOVES and prevents inconsistencies that occurred in MOVES2010.
Methane and non-methane hydrocarbons in MOVES2010a and later versions are now calculated
by applying a multiplicative factor (CH4THCRatio in the MethaneTHCRatio table) to the
calculated THC value after all adjustments to THC have been made for all fuel types as
described in the speciation report.8 The MethaneTHCRatio stores the CH4THCratio according to
the following fields:
• Vehicle source type (sourceTypelD)
• Age (ageGroupID)
• Fuel (fuelTypelD)
• Process (processID), including running, start, evaporative processes, extended idle, and
APU
The ratios are applied to all operating modes for an emission process. The methane/THC ratio for
evaporative and refueling emission processes for all vehicles is zero because methane gas is not
found in liquid fuels such gasoline, diesel or E-85 fuels and is not formed during in-tank
weathering.
3.1 Gasoline-fueled Vehicles
As discussed in the MOVES2010a energy updates report, a series of MOVES runs were used to
create the methane/THC ratios for MOVES2010a for gasoline vehicles. These values continue to
be used in MOVES2014. The MOVES2014 methane/THC values gasoline vehicles are shown in
10
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Figure 3-1. As shown, the methane/THC values vary according to age, with the methane/THC
ratios being higher for age 0-3 vehicles than for aged vehicles. This trend is an outcome of the
available data and process used to derive the methane/THC emission rates for MOVES. As
mentioned above, the methane emission rates in MOVES2010 did not vary according to age,
while the THC emission rates increased due to deterioration effects. This caused the
methane/THC ratios to decrease with age for these vehicle types. In the future, we plan on
improving these ratios with additional data.
Figure 3-1. Gasoline Methane/THC ratio by model year, sourcetype, and pollutant process. 1980 and earlier
fractions are equal to 1980, and 2030 and later are equal to the 2030 fractions. The grey points are all the
gasoline methane/THC ratios for running and start exhaust across all vehicle source types and age groups.
ageGroupName
— 0 to 3 years old
• • • 20 or more years old
0.04
1980 1990 2000 2010 2020 203019SO 1990 2000 2010 2020 2030
modelYearlD
11
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3.2 E85-ftieled Vehicles
MOVES2014 restored the capability of modeling methane emissions from vehicles using fuels
with 70 percent or more ethanol by volume (i.e., E85 fuel). MOVES2004 included methane
emission rates for ethanol fueled vehicles, but MOVES2010 did not include methane/THC
values for vehicles fueled with E85.
The MOVES2014 methane/THC ratios for E85 were derived from the EPAct Phase 3 program.9
The LA92 test cycle was used with emissions measured over three phases analogous to those in
the Federal Test Procedure (FTP), at an ambient temperature of 75°F. Emissions measured
include total hydrocarbons (THC) and methane (CFU) from four Tier-2 certified flexible-fuel
vehicles (FFVs) running on E85 fuel.
The methane/THC ratios were calculated separately for running exhaust and start exhaust
emissions from each FFVs and then averaged by emissions processes. The age effects assumed
for gasoline-fueled vehicles were applied to the methane/THC ratios for E85-fueled vehicles as
shown in Table 3-1. These ratios apply to all model years.0 Note, MOVES2014 models E85 use
only for passenger cars, passenger trucks and light commercial trucks.7
Table 3-1. Methane/THC ratios by age for Ethanol (E85) fueled vehicles in MOVES2014 for all model years,
and all applicable source types (21,31 and 32)
Age Group
0 to 3 years old
4 or 5 years old
6 or 7 years old
8 or 9 years old
10 to 14 years old
15 to 19 years old
20 or more years old
Running
Exhaust
0.779
0.404
0.356
0.300
0.204
0.174
0.172
Start
Exhaust
0.300
0.155
0.137
0.115
0.079
0.067
0.066
Consistent with the literature, Figure 3-2 shows that the methane/THC ratios for E85 are higher
in MOVES2014 than the ratios for gasoline-fueled vehicles. 10'u
Because the data used to derive the methane/THC ratios for E85 fueled vehicles are based on Tier 2 vehicles, there is more
uncertainty in the ratios for 2000 and older technology vehicles running on high ethanol blends in MOVES2014. However, pre-
2001 flex-fuel vehicles are minor portion of the light-duty gasoline fleet. For example, the default MOVES2014 population
indicates that less than 1-3% of the 1998-2000 model year light-duty gasoline vehicles are flex-fuel vehicles and MOVES2014
doesn't include any flex-fuel vehicles earlier than model year 1998. Additionally, the number of flex-fuel vehicles that use high
ethanol blends is limited; making pre-2001 MY, high-ethanol blend fueled vehicles a small portion of the vehicle emissions
inventory.
12
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Figure 3-2. Methane/THC ratios by age, and source type for Gasoline and Ethanol (E85) fueled vehicles in
model year 2005 and later
fuelTypeDesc
-*- Ethanol (E-85)
•"- Gasoline
3.3 Diesel-fueled Vehicles
The methane/THC values from diesel vehicles are unchanged in MOVES2014 from
MOVES2010a. Figure 3-3 displays the methane/THC values for running, start, and extended idle
exhaust from diesel vehicles across all source types and ages. The methane/THC values for pre-
2007 diesel vehicles were developed by calculating the ratio between the THC and methane
emission rates in the MOVES2010 version, as was done for gasoline-fueled vehicles. For MY
2006 and earlier, these values are quite low, ranging from O.OOlto 0.057 with an average of
0.003 as shown in Figure 3-3.
For 2007 and later, all diesel source types of all ages have the same methane/THC value of
0.5846 for start, running, and extended idling emissions. The methane ratio for 2007 and later
model year diesel trucks was derived from diesel vehicle emission testing conducted in Phase I
of the Health Effects Institute (HEI) Advanced Collaborative Emissions Study (ACES).12 The
methane/THC fraction for auxiliary power units is a constant 0.003 methane/THC ratio for all
model years.
13
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Figure 3-3. Diesel Methane/THC ratios for running and start exhaust. The solid line is the Methane/THC
ratio for Combination Long-haul (SourceTypeID=62), running exhaust (polProcessID= 1) and between 0-3
years old (ageGroupID = 3). The grey points are all the methane/THC ratios for running and start exhaust
across all diesel vehicle source types and age groups.
u.ou
0.55-
0.50-
— 0.45-
2 0.40 -
^0.35-
tO.30-
0)
C0.25-
(0
£0.20-
|;0.15-
0.10-
0.05-
o.oo-
f
^UUCXXJCXJUUUUUUUUUUUUUUt
1980 1990 2000 2010
modelYearlD
2020
2030
3.4 Compressed Natural Gas-fueled Transit Buses
MOVES2014 models emissions from CNG transit buses. The methane/THC ratios were updated
in MOVES2014 based on measurements conducted on CNG transit buses from the Washington
Metropolitan Area Transit Authority13 as documented in the MOVES2014 Heavy-Duty Emission
Rate Report.5 MOVES uses two different methane/THC values for CNG transit buses that are
differentiated by model year as shown in Table 3-2. The values extend back to model year 1960
and apply to all age groups, however CNG transit buses enter the fleet starting in model year
1990 in the MOVES2014 default vehicle population.
Table 3-2 Methane/THC ratios for CNG- transit buses in MOVES2014
Model
Year
1960-2001
2002-2050
CH4/THC Ratio
0.917
0.950
Currently, we do not estimate evaporative or refueling emissions from CNG vehicles in MOVES
and thus have no methane/THC ratios for these values. This is an area for future research.
14
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4 Nitrous Oxide Emission Rates
4.1 Gasoline and Diesel-Fueled Vehicles
The nitrous oxide (N2O) emission rates had only minor updates in MOVES2014. As
detailed in the MOVES2010a energy and greenhouse gas emission rate report4, the N2O
emission rates are derived from emission tests measured on the Federal Test Procedure
(FTP) and supplemented with N2O emission rates from the Inventory of U.S. Greenhouse
Gas Emissions and Sinks: 1990-2006 report.19
The N2O emission rates are modeled with a single running operating mode, and a single
start operating mode. The N2O emission rates are stored in the emissionrate table, and,
unlike most pollutants, the emission rates do not vary by vehicle age. As discussed in the
previous energy and greenhouse gas update, the running and start emissions are derived
from the composite FTP emission rates by using bag 2 of the FTP to estimate the average
running emission rates (in grams per hour), and then estimating the start emissions as the
remainder of the composite emissions4.
Table 4-1 and Table 4-2 list the FTP composite N2O emission rates, the calculated running rates
(in grams per hour), and start rates (in grams per start).
15
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Table 4-1: Composite FTP NiO emissions, running and start for gasoline vehicles
Vehicle Type /
Control Technology
Motorcycles
Non-Catalyst Control
Uncontrolled
Gasoline Passenger Cars
EPA Tier 2
LEVs
EPA Tier 1
EPA Tier 0
Oxidation Catalyst
Non-Catalyst Control
Uncontrolled
Gasoline Light-Duty Trucks
EPA Tier 2
LEVs
EPA Tier 1
EPA Tier 0
Oxidation Catalyst
Non-Catalyst Control
Uncontrolled
Gasoline Heavy-Duty Vehicles
EPA Tier 2
LEVs
EPA Tier 1
EPA Tier 0
Oxidation Catalyst
Non-Catalyst Control
Uncontrolled
FTP Comp
f g / mile)
0.0069
0.0087
0.0050
0.0101
0.0283
0.0538
0.0504
0.0197
0.0197
0.0066
0.0148
0.0674
0.0370
0.0906
0.0218
0.0220
0.0134
0.0320
0.1750
0.0814
0.1317
0.0473
0.0497
Running
(g / hour)
0.0854
0.1076
0.0399
0.0148
0.2316
0.6650
0.6235
0.2437
0.2437
0.0436
0.0975
0.6500
0.2323
0.8492
0.2044
0.2062
0.1345
0.3213
1.7569
0.8172
1.3222
0.4749
0.4990
Start
(s. 1 start)
0.0189
0.0238
0.0221
0.0697
0.1228
0.1470
0.1379
0.0539
0.0539
0.0325
0.0728
0.2546
0.1869
0.3513
0.0845
0.0853
0.0486
0.1160
0.6342
0.2950
0.4773
0.1714
0.1801
16
-------
Table 4-2. Composite FTP NiO emissions, composite, running and start for diesel vehicles
Vehicle Type /
Control Technology3
Diesel Passenger Cars
Advanced
Moderate
Uncontrolled
Diesel Light-Duty Trucks
Advanced
Moderate
Uncontrolled
Diesel Heavy-Duty Vehicles
Advanced
Moderate
Uncontrolled
FTP Comp
(g / mile)
0.0010
0.0010
0.0012
0.0015
0.0014
0.0017
0.0049
0.0048
0.0048
Running
(g / hour)
0.0168
0.0168
0.0202
0.0253
0.0236
0.0286
0.0828
0.0809
0.0809
Start
(g / start)
0.0010
0.0010
0.0012
0.0015
0.0014
0.0018
0.0051
0.0049
0.0049
a Table 8-5 defines the model year group definitions of the diesel control technologies groups
The N2O emission rates are applied in MOVES using model year group ranges that map to
technology distinctions. Table 8-1 through Table 8-5 in the Appendix provide the distribution of
vehicles types/technology types by model year. The running and start emission rates in Table 4-1
and Table 4-2 are multiplied by the model-year specific technology penetrations to provide
model year specific emission rates in MOVES. The values in Table 8-1 through Table 8-5 are
taken directly from the Inventory of the US GHG emissions and sinks, Annex Tables A-84
through A-8719, except for the few instances as noted in the footnotes of the tables.
Figure 4-1 displays the model year-specific N2O emission rates used in MOVES2014 for
gasoline and diesel-fueled vehicles that are calculated as the product of the technology-specific
rates provided in Table 4-1 and Table 4-2 and the model-year/technology penetrations provided
in the Appendix. In general, MOVES2014 uses the model-year specific rates. However, for
2001-2010 MOVES has a single N2O emission rate to represent the range of model year groups,
and the emission rate for these model year groups in MOVES is the average of the model-year
specific rates. MOVES2014 uses the same N2O emission rate within vehicle class and fuel type
for 2011 through 2050 model year vehicles.
17
-------
Figure 4-1. NiO emission rates for running and start processes for gasoline and diesel vehicles in
MOVES2014. The NiO emission rates are constant from 1960-1970 model year and are constant from 2011-
2050 model years
0.08-
0.06-
0.04-
0.02-
89
O
•& o.oo-
running, Diesel Fuel
J II 1 1 1 1 1 Illl II 1 1 1 1 1 1 II 1 1
™\HHHI
^
<2
E
LU
O 0.005-
CM
z
0.004-
0.003-
0.002-
0.001 -
0.000
1.5-
1.0-
0.5-
running, Gasoline
0.0-
1970 19SO 1990 2000 2010 2020 1970 19SO 1990 2000 2010 2020
start, Diesel Fuel
0.6-
0.2-
0.0
start. Gasoline
Veh.Type
-*- Motorcycle
-^ LDV
LOT
HD
1970 19SO 1990 2000 2010 2020 1970 1930 1990 2000 2010 2020
modelYearlD
18
-------
4.2 Alternative-Fueled Vehicles
MOVES2004 included N2O emission rates for alternative fuels, including E85 and compressed-
natural gas fueled vehicles. The N2O emission rates were based on limited data from the Sources
and Sinks report.19 In MOVES2014, we updated the N2O emission rates for ESS-fueled vehicles
to use the same emission rates as gasoline vehicles. We will revisit the N2O E85 rates as more
data becomes available.
Compressed natural gas (CNG) transit buses use the emission rates reported in Table 4-3. These
rates remain unchanged from the numbers reported for MOVES2010a.4 However, in
MOVES2014, the N2O emission rates were modified so they apply only to Urban Bus
(regClassID 48) vehicles fueled by CNG, and do not apply for any other vehicle type, since in
MOVES2014, CNG is an allowed fuel for transit buses only. The composite emission rate was
obtained from the Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-200619, and
disaggregated into running and starts using the same relative running and start splits as heavy-
gasoline vehicles.
Table 4-3: Nitrous oxide emission Rates for CNG-fueled transit buses
FTP Comp
(g / mile)
0.175
Running
(g / hour)
1.6797
Starts
(g / start)
0.6636
19
-------
5 Carbon Dioxide (COz) Emission Rates
5.1 Carbon Dioxide Calculations
MOVES does not store carbon dioxide emission rates in the emission rate tables (e.g. CCh/mile
or CCh/hour operation), but calculates carbon dioxide emissions from total energy consumption
as shown in Equation 5-1.
/44\
C02 = Total Energy Consumed x Carbon Content x Oxidation Fraction x I — 1 Equation 5-1
Carbon content is expressed in units grams of carbon/KJ of energy consumed. Oxidation fraction
is the fraction of carbon that is oxidized to form CO2 in the atmosphere. A small mass percentage
of fuel is emitted as carbon monoxide, organic gases and organic carbon. Currently, MOVES
assumes an oxidation fraction of 1 for all the hydrocarbon-based fuels. The value (44/12) is the
molecular mass of CO2 divided by the atomic mass of carbon.
The carbon content and oxidation fractions used to calculate CO2 emissions are provided in
Table 5-1. The carbon content values used in MOVES were developed for MOVES20043 based
on values derived from the life-cycle model GREET.
Table 5-1. Carbon content, xxidation fraction and energy content by fuel subtype
fuelSubtypelD
10
11
12
13
14
15
20
21
22
30
40
50
51
52
18
90
fuelTypelD
2
2
2
3
4
5
5
5
1
9
Fuel Subtype
Conventional Gasoline
Reformulated Gasoline (RFG)
Gasohol (E10)
Gasohol (E8)
Gasohol (E5)
Gasohol (E15)
Conventional Diesel Fuel
Biodiesel
Fischer-Tropsch Diesel
(FTD100)
Compressed Natural Gas (CNG)
Liquefied Petroleum Gas (LPG)
Ethanol
Ethanol (E85)
Ethanol (E70)
Ethanol (E20)
Electricity
Carbon
Content
(g/KJ)
0.0196
0.0196
0.0196
0.0196
0.0196
0.0196
0.0202
0.0201
0.0207
0.0161
0.0161
0.0194
0.0194
0.0194
0.0194
0
Oxidation
Fraction
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
20
-------
5.2 Carbon Dioxide Equivalent Emissions
CO2 equivalent is a combined measure of greenhouse gas emissions weighted according to the
global warming potential of each gas, relative to CO2. Although the mass emissions of CH4 and
N2O are much smaller than CO2, the global warming potential is higher, which increases the
contribution of these gases to the overall greenhouse effect. CO2 equivalent is calculated from
CO2, N2O and CH4 mass emissions according to Equation 5-2.
C02 equivalent = C02 x GWPC02 + CH4 x GWPCH/i + N20 x GWPN2o
Equation 5-2
GWP is Global Warming Potential. MOVES uses thelOO-year Global Warming Potentials listed
in Table 5-2 and stored in the Pollutant table of the MOVES Default Database. The GWP values
for methane and nitrous oxide were updated in MOVES2014 with the values used in the 2007
IPCC Fourth Assessment Report (AR4), which is consistent with values used in recent the LD
GHG 2017+ rule and the HD GHG Phase 2 NPRM.
Table 5-2.100-year Global Warming Potentials used in MOVES
Pollutant
Methane (CH4)
Nitrous Oxide (N2O)
Atmospheric CO2
Global Warming Potential (GWP)
25
298
1
21
-------
6 Fuel Consumption Calculations
MOVES reports fuel consumption in terms of energy use, but does not report fuel usage in term
of volume or mass. However, MOVES calculate fuel usage in terms of volume and mass within
the refueling14 and sulfur dioxide emission calculators, respectively.15
MOVES uses energy content and the density of the fuel to calculate fuel volume, as presented in
Equation 6-1 and the values in Table 6-1.
Fuel (gallons') = Energy (K]} x
energyContentJ \KJ
gallons\
„ , .. Equation 6-1
fuelDensityJ\ g J
The fuel density and the energy content values are stored in the fuel type and fuel subtype
MOVES tables, respectively. Fuel density is classified according to the more general fuel types,
and energy content varies according to fuel subtype. Because MOVES reports energy content by
fueltype, rather than fuelsubtype, the average of the energy content can be calculated for each
fueltype using the energy content of each fuel subtype using the respective fuel subtype market
share stored in the MOVES fuelsupply table. The derivation of the fuelsupply table is
documented in the report: MOVES2014 Fuel Supply Defaults16.
Table 6-1. Fuel density and energy content by fuel type in MOVES2014
fuelTypelD
2
2
2
3
4
5
5
5
9
fuelSubtypelD
10
11
12
13
14
15
18
20
21
22
30
40
50
51
52
90
fuelSubtypeDesc
Conventional Gasoline
Reformulated Gasoline (RFG)
Gasohol (E10)
Gasohol (E8)
Gasohol (E5)
Gasohol (E15)
Ethanol (E20)
Conventional Diesel Fuel
Biodiesel
Fischer-Tropsch Diesel
(FTD100)
Compressed Natural Gas (CNG)
Liquefied Petroleum Gas (LPG)
Ethanol
Ethanol (E85)
Ethanol (E70)
Electricity
Fuel Density
(g/gallons)
2839
2839
2839
2839
2839
2839
2839
3167
3167
3167
NULL
1923
2944
2944
2944
NULL
Energy Content (KJ/g)
43.488
42.358
41.762
42.1
42.605
40.92
40.077
43.717
43.061
43.247
48.632
46.607
26.592
29.12
31.649
NULL
22
-------
7 Appendix A. Timeline of Energy and GHG emissions in MOVES
• MOVES20043
o Released with a full suite of energy, methane, rates to allow estimation of fuel
consumption and GHG emissions.
o Energy rates developed at a fine level of detail by vehicle attributes including
classes for engine technologies, engine sizes, and loaded weight classes. The
emission rates were created by analyzing second by second (1 Hz) resolution
data from 16 EPA test programs covering approximately 500 vehicles and 26
non-EPA test programs covering approximately 10,760 vehicles.
o "Holes" in the data were filled using either the Physical Emission Rate
Estimator (PERE)17 or interpolation.
o Energy consumption at starts increases at temperatures < 75F
• MOVES2009
o Updates of Nitrous Oxide (N2O) and methane (CH4) emission rates
• Based on an enlarged database of Federal Test Procedure (FTP)
emission tests and the Inventory of U.S. Greenhouse Gas Emissions
and Sinks: 1990-200618,19
o Energy start rates adjusted for soak time
• MOVES2010
o Heavy-duty energy rates replaced based on new data and analysis using scaled
tractive power (STP) methodology5
o Light-duty rates updated to include 2008-2011 model year 2011 Corporate
Average Fuel Economy (CAFE) Standards for light trucks
• MOVES2010a4
o Updates to the MOVES database to reflect new data and projections for 2008
and newer light duty energy rates
• Model year 2008-2010 vehicle data
• Model year 2011 Fuel Economy (FE) final rule projections
• Model year 2012-2016 FE/GHG final rule projections
• Corrections to model year 2000+ light duty diesel energy start rates
o Modifications to the organization of energy rates in MOVES database (DB)
• Improved consistency between energy rates and other MOVES
emission rates.
• Redefined energy rate structure
• Removed engine size classes, and consolidated the loaded weight
classes to a single weight class for each regulatory class
• Removed unused engine technologies and emission rates from the
MOVES DB
o Updates to the methane algorithm such that methane is calculated as a fraction
of total hydrocarbons (THC)
• MOVES2010 methane and THC emission rates used to derive
methane/THC ratios
• MOVES2014
o Medium and heavy duty energy rates reduced for 2014 and later model years
vehicles to account for the Phase 1 of the Greenhouse Gas Emissions
23
-------
Standards and Fuel Efficiency Standards for Medium- and Heavy-Duty
Engines and Vehicles2
o Light Duty energy rates reduced for 2017 and later model years vehicles to
account for the Light-duty EPA and NHTSA greenhouse gas and fuel
economy standards1
24
-------
8 Appendix B: Emission Control Technology Phase-In used for N20
Emission Rate Calculations.
fable 8-1 Conl
excei
Model
Years
1973-1974
1975
1976-1977
1978-1979
1980
1981
1982
1983
1984-1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006+
rol Technology Assignments for Gasoline Passenger Cars (Percent of VMT). Reproduced with
ptions from Table A-84 from Inventory of US GHG Emissions and Sinks: 1990-2006.
Non-Catalyst
Control
100%
20%
15%
10%
5%
Oxidation
Catalyst
80%
85%
90%
88%
15%
14%
12%
EPA Tier 0
7%
85%
86%
88%
100%
60%
20%
1%
1%
0%
0%
EPA Tier 1
40%
80%
97%
97%
87%
67%
44%
3%
1%
0%
0%
LEVs
2%
3%
13%
33%
56%
97%
99%
87%
41%
38%
0%
EPA Tier 2
13%
59%
62%
100%a
a We assume 100% EPA Tier 2 emission rates for model years 2006 and forward which differs from the US GHG
Emissions and Sinks.
25
-------
Table 8-2 Control Technology Assignments for Gasoline Light-Duty Trucks (Percent of VMT) Reproduced
with exceptions from Table A-85 from Inventory of US GHG Emissions and Sinks: 1990-2006.
Model
Years
1973-1974
1975
1976
1977-1978
1979-1980
1981
1982
1983
1984
1985
1986
1987-1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006+
Not
Controlled
0%
Non-
Catalyst
Control
100%
30%
20%
25%
20%
Oxidation
Catalyst
70%
80%
75%
80%
95%
90%
80%
70%
60%
50%
5%
EPA
TierO
5%
10%
20%
30%
40%
50%
95%
60%
20%
EPA
Tierl
40%
80%
100%
100%
80%
57%
65%
1%
10%
<1%
LEVs
20%
43%
35%
99%
90%
53%
72%
38%
EPA
Tier 2
47%
28%
62%
100%a
a We assume 100% EPA Tier 2 emission rates for model years 2006+, which differs from the US GHG Emissions
and Sinks.
26
-------
Table 8-3 Control Technology Assignments for Gasoline Light-Duty Trucks (Percent of VMT) Reproduced
with exceptions from Table A-85 from Inventory of US GHG Emissions and Sinks: 1990-2006.
Model
Years
1973-1974
1975
1976
1977-1978
1979-1980
1981
1982
1983
1984
1985
1986
1987-1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006+
Not
Controlled
0%
Non-
Catalyst
Control
100%
30%
20%
25%
20%
Oxidation
Catalyst
70%
80%
75%
80%
95%
90%
80%
70%
60%
50%
5%
EPA
TierO
5%
10%
20%
30%
40%
50%
95%
60%
20%
EPA
Tierl
40%
80%
100%
100%
80%
57%
65%
1%
10%
<1%
LEVs
20%
43%
35%
99%
90%
53%
72%
38%
EPA
Tier 2
47%
28%
62%
100%a
a We assume 100% EPA Tier 2 emission rates for model years 2006+, which differs from the US GHG Emissions
and Sinks.
27
-------
Table 8-4 Control Technology Assignments for Gasoline Heavy-Duty Vehicles (Percent of VMT) Reproduced
with exceptions from Table A-86 from Inventory of US GHG Emissions and Sinks: 1990-2006.
Model
Years
Pre-1982
1982-
1984
1985-
1986
1987
1988-
1989
1990-
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006+
Not
Controlled
100%
95%
Non-
Catalyst
Control
95%
70%
60%
45%
Oxidation
Catalyst
5%
5%
15%
25%
30%
25%
10%
EPA
TierO
15%
15%
25%
10%
5%
EPA
Tierl
65%
85%
96%
78%
54%
64%
69%
65%
5%
LEVs
4%
22%
46%
36%
31%
30%
37%
23%
EPA
Tier 2
-
.
-
-
.
5%
59%
77%
100%a
aWe assume 100% EPA Tier 2 emission rates for model years 2006+ , which differs from the US GHG Emissions
and Sinks.
28
-------
Table 8-5 Control Technology Assignments for Diesel Highway Vehicles and Motorcycles. Reproduced with
exceptions from Table A-87 from Inventory of US GHG Emissions and Sinks: 1990-2006.
Vehicle Type/Control Technology
Diesel Passenger Cars and Light-Duty Trucks
Uncontrolled
Moderate control
Advanced control
Diesel Medium- and Heavy-Duty Trucks and Buses
Uncontrolled
Moderate control
Advanced control
Motorcycles
Uncontrolled
Non-catalyst controls
Model
Years
1960-1982
1983-1995
1996-
2006+3
1960-1982
1983-1995
1996-2006+
1960-1995
1996-2006+
aln MOVES we continue using the 1996-2006 rates for all model years beyond 2006. The 2013 US GHG Emissions
and Sinks updates the Advanced Control to up to 2011 model year vehicles, and adds a new category of diesel
(aftertreatment diesel). However, the N2O emission rates of aftertreatment diesel are unchanged from advanced
control.20
29
-------
9 References
1 USEPA (2012). 2017 and Later Model Year Light-Duty Vehicle Greenhouse Gas Emissions and Corporate
Average Fuel Economy Standards (77 FR No. 199, October 15, 2012)
2 USEPA (2011). Greenhouse Gas Emission Standards and Fuel Efficiency Standards for Medium- and Heavy-Duty
Engines and Vehicles (76 FR 57106, September 15, 2011)
3 USEPA (2005). Energy and Emissions Inputs. EPA-420-P-05-003. Office of Transportation and Air Quality. US
Environmental Protection Agency. Ann Arbor, MI. March, 2005.
http://www.epa.gov/otaq/models/ngm/420p05003.pdf.
4 USEPA (2012). Updates to the Greenhouse Gas and Energy Consumption Rates in MOVES2010a. EPA-420-R-
12-025. Office of Transportation and Air Quality. US Environmental Protection Agency. Ann Arbor, MI. August,
2012. http://www.epa.gov/otaq/models/moves/documents/420rl2025.pdf.
5 USEPA (2015). Exhaust Emission Rates for Heavy-Duty On-mad Vehicles in MOVES2014. EPA-420-R-15-004.
Assessment and Standards Division. Office of Transportation and Air Quality. US Environmental Protection
Agency. Ann Arbor, MI. September, 2015. http://www.epa.gov/otaq/models/moves/moves-reports.htm.
6 USEPA (2009). Draft MOVES2009 Highway Vehicle Population and Activity Data. EPA-420-P-09-001. Office of
Transportation and Air Quality. US Environmental Protection Agency. Ann Arbor, MI. August, 2009.
http://www.epa.gov/otaq/models/moves/moves-reports.htm.
7 USEPA (2015). Population and Activity of On-mad Vehicles inMOVES2014. EPA-420-D-15-001. Assessment
and Standards Division. Office of Transportation and Air Quality. US Environmental Protection Agency. Ann
Arbor, MI. 2015. http://www.epa.gov/otaq/models/moves/moves-reports.htm.
8 USEPA (2014). Speciation of Total Organic Gas and P articulate Matter Emissions from On-road Vehicles in
MOVES2014. EPA-420-R-14-020. Ann Arbor, MI. October, 2014. http://www.epa.gov/otaq/models/moves/moves-
reports.htm.
9 USEPA (2013). Assessing the Effect of Five Gasoline Properties on Exhaust Emissions from Light-Duty Vehicles
certified to Tier-2 Standards: Analysis of Data from EPAct Phase 3 (EPAct/V2/E-89). Final Report. EPA-420-R-
13-002. Assessment and Standards Division, Office of Transportation and Air Quality, Ann Arbor, MI. April,
2013.
10 Yanowitz, J, and McCormick, R (2009). Effect ofE85 on Tailpipe Emissions from Light-Duty Vehicles. J. Air &
Waste Manage. Assoc. 59:172-182.
11 Graham, L., Belisle, S., and Baas, C. (2008). Emissions from Light Duty Gasoline Vehicles Operating on Low
BlendEthanol Gasoline andE85. Atmospheric Environment. 42:4498-4516. June 2008.
12 Khalek, I., T. Rougher and P. Merrit (2009). Phase 1 of the Advanced Collaborative Emissions Study. CRC
Report: ACES Phase 1.
13 Melendez, M. T., J; Zuboy, J (2005). Emission Testing of Washington Metropolitan Area Transit Authority
(WMATA) Natural Gas and Diesel Transit Buses. NREL/TP-540-36355. December 2005.
14 USEPA (2014). Evaporative Emissions from On-road Vehicles in MOVES2014. EPA-420-R-14-014. Assessment
and Standards Division. Office of Transportation and Air Quality. US Environmental Protection Agency. Ann
Arbor, MI. September, 2014. http://www.epa.gov/otaq/models/moves/moves-reports.htm.
15 USEPA (2015). Fuel Effects on Exhaust Emissions from On-road Vehicles inMOVES2014. EPA-420-R-15-001.
Assessment and Standards Division. Office of Transportation and Air Quality. US Environmental Protection
Agency. Ann Arbor, MI. 2015. http://www.epa.gov/otaq/models/moves/moves-reports.htm.
16 USEPA (2015). Fuel Supply Defaults: Regional Fuels and the Fuel Wizard in MOVES2014. EPA-420-R-15-002.
Assessment and Standards Division. Office of Transportation and Air Quality. US Environmental Protection
Agency. Ann Arbor, MI. 2015. http://www.epa.gov/otaq/models/moves/moves-reports.htm.
17 USEPA (2005). Fuel Consumption Modeling of Conventional and Advanced Technology Vehicles in the Physical
Emission Rate Estimator (PERE). EPA420-P-05-001. Office of Transportation and Air Quality. US Environmental
Protection Agency. Ann Arbor, MI. February, 2005. http://www.epa.gov/otaq/models/ngm/420p05001.pdf.
18 USEPA (2012). Updates to the Greenhouse Gas and Energy Consumption Rates inMOVES2010a. EPA-420-R-
12-025. Office of Transportation and Air Quality. US Environmental Protection Agency. Ann Arbor, MI. August,
2012. http://www.epa.gov/otaq/models/moves/documents/420rl2025.pdf.
19 USEPA (2008). Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2006. U.S. Environmental
Protection Agency. 1200 Pennsylvania Avenue, N.W. Washington, DC 20460. April 15, 2008.
20 USEPA (2013). Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2013. U.S. Environmental
Protection Agency. 1200 Pennsylvania Avenue, N.W. Washington, DC 20460. April 15, 2015.
30
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http://www.epa.gov/climatechange/Downloads/ghgemissions/US-GHG-Inventory-2013-Annex-3-Additional-
Source-or-Sink-Categories.pdf
31
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