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Alternatives to Traditional
Transportation Fuels 1994

Volume 2

Greenhouse Gas Emissions

3. Greenhouse Gases
Emitted From Transportation Uses

In the United States, transportation
is a multimodal system of highway, mass transit, air, rail, waterborne, and
pipeline transport. Light trucks [39]
are becoming a greater proportion of the surface transportation fleet,
accounting for almost 40 percent of new vehicle purchases. These vehicles, as
well as conventional automobiles (collectively known “light-duty”
vehicles), are the basis in this report for GHG emissions resulting from fuel
combustion.

In 1990, highway travel accounted for 85 percent of total passenger miles
traveled, air travel for 11 percent, and rail and bus travel for 4 percent.
In addition, more than 3.1 trillion ton-miles of freight are moved in the
United States each year. A 50-percent increase in vehicle miles traveled
since 1969 has been partly offset by a 34 percent decrease (equivalent to an
increase in efficiency of 7 miles per gallon) in the amount of fuel consumed
per mile. Fossil fuels account for approximately 85 percent of U.S. energy
consumed, with the remaining 15 percent coming from renewable and other
energy sources [40].

Motor vehicle greenhouse gas (GHG) emissions are projected to grow in the
United States and throughout the world as the result of increasing vehicle
miles traveled (VMT). EIA projects a 1.4 percent VMT growth per year from
1994 to 2015 in the U.S. compared with a 5.5 percent growth rate between 1980
and 1990 [41].
The 1990 Nationwide Personal Transportation Survey (NPTS) [42]
suggests that vehicle miles traveled will increase at a rate about double the
population growth. The greatest growth in vehicle miles traveled is expected
to come from non-work-related trips and increases in commuting distances,
which are associated with suburban sprawl. These trends are occurring not
only in the United States but also in all major cities around the world and
promise to continue even if economic growth is minimal. Moreover, the rate of
increase in vehicle ownership in Asia and Africa is greater than in the
United States and elsewhere (Table 4). Removing the 55 mile-per-hour speed
limit will also add to GHG emissions' growth.

Table
4. Worldwide Vehicle Ownership Trends (Vehicles per Person)

Area

1980

1990

Percent Change

Africa

0.013

0.021

61.5

Asia

0.019

0.033

73.7

United
States

0.588

0.769

30.8

South
America

0.067

0.083

23.9

Europe

0.217

0.278

28.0

Source: Decision Analysis
Corporation, Measurement of Emissions: Greenhouse Gas Estimates for
Alternative Transportation Fuels, unpublished final report prepared for
the Energy Information Administration (Vienna, VA, December 1995).

The transportation sector contributes about one-third of total carbon dioxide
emissions in the United States and other countries that belong to the
Organization for Economic Cooperation and Development [43].
Annual worldwide carbon dioxide produced from motor vehicle use is estimated
at around 0.32 trillion moles (14 trillion grams), or about 20 percent of
total carbon dioxide production [44].

GHGs contribute to the greenhouse effect through different amplification
rates (effectivenesses) over varying time periods (Table 5). These total
effects are referred to as “weighted,” or the GWP of each GHG.
One of the main reasons for weighting GHGs is that each gas absorbs radiation
at a different energy level, with a different coefficient of absorption, and
has a different residence time, or decay time, in the atmosphere. Although
weighting is the best way to estimate the actual effect of various GHGs, the
assumptions needed to arrive at GWP values for some GHGs (e.g., methane and
nitrogen oxides) are at best very approximate. Recent data on atmospheric
methyl chloroform concentrations indicate that hydroxyl radical (OH*) concentrations
are about 20 percent greater than previously estimated, and the revision of
these data leads to the projection of a shorter atmospheric methane lifetime
than previously estimated [45]
[46].
These findings suggest that the actual greenhouse effects for methane,
nonmethane hydrocarbons, and oxides of nitrogen are probably lower than the
values presently used because the residence times for these GHGs were
developed based on lower estimates of hydroxyl radical concentration in the
atmosphere.

Table 5. Greenhouse Gases and Their Potential
Contribution to Global Warming

Greenhouse Gas

Relative Effectivenessa

Decay Timeb (years)

Relative Contributionc
in 100 Years

per Kilogram

per Mole

per Kilogram

per Mole

Carbon
Dioxide (CO2)

1

1

120-500d

1

1

Methane
(CH4)

70

25

7-14.5

15-30

5-10

Nitrous
Oxide (N2O)

210

210

120

320

320

Ozone
(O3)

1,800

2,000

0.01

3

4

CFC-11

4,000

12,000

50

4,000

11,000

CFC-12

6,000

15,000

102

8,500

21,250

aThe greenhouse effectiveness of
a gas in the atmosphere depends, in part, on its concentration. As the
atmospheric concentration of a gas increases, the effectiveness of
additional gas decreases. The relative effectiveness means the
effectiveness of a greenhouse gas relative to carbon dioxide. The relative
effectiveness refers to global warming potential (GWP) of a gas relative to
carbon dioxide GWP.

bThe decay time is a rough measure of how long the greenhouse
gas remains in the atmosphere. If the decay time is 150 years, one-half of
the initial amount remains in the atmosphere after 150 years.

cThe relative contribution is the accumulated greenhouse effect
as the integral of the greenhouse effect over time, when each gas is
undergoing an exponential decrease, while at the same time being added to
by continuing industrial emissions.

dH. Rhode, “A Comparison of the Contribution of Various
Gases to the Greenhouse Effect,” Science 248 (1990):1217-1219.
U.S. Department of Energy, A Primer on Greenhouse Gases,
DOE/NBB-0083 (Washington, DC, March 1988).

CFC-11 = CCl3F. CFC-12 = CCl2F2.

Note: Global warming potential for water vapors is not available.

Sources: David M. Gates, Climate Change and Its Biological Consequences
(Sunderland, MA: Sinauer Associates Publishers, Inc. 1993), p. 9; Energy
Information Administration, Emissions of Greenhouse Gases in the United
States 1987-1994, DOE/EIA-0573(87-94) (Washington, DC, October 1995),
p. 6.

The two most important variables in calculating the GWP of a greenhouse gas
are its “instantaneous radiative forcing” and atmospheric
residence time (see Appendix
A for details). Radiative forcing values greatly depend not only on GHG
concentrations (including absorption bands overlap and reactivity of GHGs),
but also on the vertical (altitude) and horizontal distribution of GHGs (see
Appendix D for details about the overlap of the absorption bands of GHGs).
Except for carbon dioxide, all other major GHG vertical and horizontal (i.e.,
altitude and surface area, respectively) distribution profiles vary greatly.
The radiative forcing may be a function of horizontal and vertical
distribution of greenhouse gases, leading to variable GWPs at different
locations. The variable GWP values will actually be very useful in estimating
or forecasting regional impacts of GHGs.

The estimates presented in Table
1 show both unweighted and weighted GHG emissions [47],
while Tables 7 through 12 show only unweighted emissions. (To obtain weighted
estimates, apply the GWPs from Table
5.) The unweighted estimate measures contributions from all GHGs simply
as moles and grams of emissions for the fuel consumed per VMT. The unweighted
estimate is a good place to begin GHG analysis, particularly because the GWPs
of methane, nitrogen oxides, and water vapor are subject to considerable
uncertainty and require scientific investigation beyond the scope of the
Energy Information Administration (EIA).

Greenhouse Gas Emissions From Alternative Transportation Fuels and
Gasoline

EIA began its effort to estimate GHG emissions from replacement fuels in
1993 by examining existing literature on the subject and developing
information specific to alternative transportation fuels (ATFs) across the
fuel cycle [48].
In general, this work paralleled the framework established by Delucchi [49].
Estimates of GHGs are not based upon actual measurements from operating
vehicles, but rather on the simplified chemistry of hydrocarbon combustion in
automotive engines as formalized in the U.S. Environmental Protection Agency
(EPA) “Mobile 5a” emission model [50].
A brief overview of the combustion chemistry of alternative and traditional
transportation fuels is presented in Appendix C.

EIA uses the Decision Analysis Corporation (DAC) emissions model [51]
for the estimation of greenhouse gases emitted from the end-use of
alternative and traditional transportation fuels because the Mobile 5a model
does not provide fully for alternative transportation fuels. EIA then
combines this result with its previous estimates [52]
based on Delucchi's model to obtain the emissions from the remaining stages
of the total fuel cycle. The DAC emissions model first calculates theoretical
amounts of CO2 and water emitted from vehicles per million Btu of
fuel consumption, assuming perfect combustion. Carbon dioxide and water
emissions per million Btu are then converted to emissions in grams and/or
moles [53]
per VMT based on assumptions about miles per gallon, relative efficiencies of
different fuels, and the density of gasoline. EIA then estimates criteria
pollutant emissions in grams and/or moles per VMT for the different alternative
fuels, based on the average emission rate observed in an alternate
transportation fuel vehicles database [54].
Criteria pollutants from gasoline are provided in the model. Evaporative
emissions obtained from EPA's Mobile 5a model for different liquid fuels are
then added to arrive at total vehicle emission estimates [55].
The DAC emissions model then adjusts the theoretical water and carbon dioxide
emissions to account for all criteria pollutants and evaporative emissions.

Carbon dioxide and water vapor account for more than 97 percent of
alternative and traditional transportation fuel combustion products (Tables
6, 7, and 8). Water vapor production from gasoline-fueled vehicle combustion
is of the same magnitude as carbon dioxide; that is, they are roughly
equimolar combustion products, each totaling approximately 17.34 x 1012
moles per year in the world and 5.63 x 1012 moles per year in the
United States [56].

Table 6. Gasoline Exhaust Products per Vehicle Mile
Traveled (Grams and Moles)

Exhaust Product

Emissions

Grams

Percent of Total

Moles

Percent of Total

Carbon
Dioxide (CO2)

272.38

69.38

6.19

49.01

Water
Vapor (H2O)

109.42

27.88

6.08

48.14

Methane
(CH4)

0.08

0.02

<0.01

0.07

Nitrogen
Oxides (NOx) and Nitrous Oxide (N2O)

0.87

0.22

0.02

0.16

Carbon
Monoxide (CO)

9.00

2.29

0.32

2.53

Nonmethane
Hydrocarbons (CnHm)

0.86

0.21

0.01

0.09

Notes:
Gasoline refers to unleaded gasoline in this report. Estimates are based on
the Environmental Protection Agency's Mobile 5a model for emissions
produced by hydrocarbon combustion in automotive engines. Nitrogen oxides
include primarily nitric oxide and nitrogen dioxide. One mole of gas is
equal to the amount of substance that contains as many elementary units
(6.023 x 1023 molecules or atoms as there are atoms in 12 grams
of carbon-12. Normally, emissions are reported in grams per vehicle mile
traveled. However, reporting in moles is preferable because greenhouse gas
heat absorption is directly related to the number of molecules of gas.

Source: Decision Analysis Corporation, “Measurement of Emissions:
Greenhouse Gas Estimates for Alternative Transportation Fuels,”
unpublished final report prepared for the Energy Information Administration
(Vienna, VA, December 1995).

Table
7 and Figure 3 show the total carbon dioxide emissions per VMT for the
entire fuel cycle for different fuels. For the entire fuel cycle, CNG
produces the lowest carbon dioxide emissions, or 5.64 moles (248.2 grams) per
VMT, closely followed by liquefied petroleum gas (LPG) at 6 moles (263.5
grams) per VMT. Compressed natural gas (CNG) and LPG follow similar trends in
the vehicle stage [57].
Alcohol fuels emit less carbon dioxide in the vehicle stage than gasoline.
Total carbon dioxide emissions for the fuel cycle from corn-based ethanol is
smaller than from gasoline. Ethanol from corn produces the lowest amount of
carbon dioxide emissions in the pre-vehicle stage at 0.56 moles (24.4 grams)
per VMT due to the sequestration carbon dioxide credit of 6.8 moles (299.1
grams), followed by LPG at 0.65 moles (28.1 grams) and CNG at 0.99 moles
(43.5 grams).

D

Total fuel cycle water vapor emissions are the lowest for gasoline at 7.75
moles (139.5 grams) followed by LPG at 8.18 moles (147.3 grams) and CNG at
10.93 moles (196.8 grams) (Table
8 and Figure 3). Currently, however, water vapor from fuel combustion is
not believed to have a significant impact on atmospheric water vapor
concentrations.

All other emissions are best represented by millimoles (one-thousandth of
a mole) and milligrams (one-thousandth of a gram) rather than moles and
grams. LPG emits the least methane, 17.2 millimoles (271 milligrams) per VMT,
followed by gasoline at 22 millimoles (349 milligrams) per VMT (Table
9, Figure 4). CNG tops the list for methane emissions, producing 56.3
millimoles (900 milligrams) per VMT in the vehicle stage and 35 millimoles
(559 milligrams) per VMT in other stages. Corn-based ethanol emits the largest
amount of nitrous oxide, 9.3 millimoles (410 milligrams) per VMT, largely due
to fertilizer use (7.41 millimoles or 327 milligrams per VMT) (Table
10 and Figure 4). Because actual measurements of nitrous oxide in the
vehicle stage vary greatly, the regulatory maximum of 1.6 millimoles (70
milligrams) per VMT is used to calculate nitrous oxide emissions.

D

Table
11 shows the carbon monoxide emissions for the various fuels as being
identical--321.4 millimoles (9,000 milligrams) per VMT in the vehicle stage.
The reason is that the value shown is the regulatory maximum set within the
model with a value of 321.4 millimoles (9,000 milligrams) per VMT. These
emissions are not measured values due to the huge range of values reported in
the alternative-fueled vehicles (AFVs) database. Ethanol has the lowest total
fuel cycle carbon monoxide emissions at 258.3 millimoles (7,232 milligrams)
per VMT (Figure 5).

D

Total fuel cycle nitric oxide and nitrogen dioxide emissions for LPG and
CNG are lowest at 22.9 millimoles (870 milligrams) and 24.2 millimoles (919
milligrams), respectively, per VMT, mainly because the vehicle stage uses the
regulatory maximum value of 21.1 millimoles (800 milligrams) per VMT (Table
12 and Figure 5). Ethanol from corn emits the most nitrogen oxides--37.2
millimoles (1,417 milligrams) per VMT-- due to large releases during the
corn-growing and fuel production (fermentation) processes. At 1.8 millimoles
(70 milligrams) per VMT, LPG emits the least nitrogen oxides prior to the
vehicle stage of the fuel cycle.

An evaluation of available data on total fuel cycle emissions for five fuel
types (namely, gasoline, CNG, LPG from oil and gas, methanol from natural
gas, and ethanol from corn) and combustion chemistry results in certain
conclusions with respect to existing information on GHGs in the
transportation sector. First, ATFs would produce minimal, if any, weighted
GHG reductions if water vapor were taken into account. For a variety of
reasons, however, most current analyses of GHGs do not include water vapor as
a greenhouse gas in analyzing fuel emissions. For instance, some analysts
question whether the marginal addition of water vapor from fuels, except
emissions from high-flying aircraft [58],
has a measurable impact, compared with the impact of “background”
levels of water vapor in the atmosphere. The relation between surface sources
and atmospheric concentrations of water vapor is complicated and indirect.
Second, CNG produces the lowest level of carbon dioxide emissions across the
total fuel cycle, followed by LPG and ethanol from corn. Third, CNG produces
the largest methane emissions across the total fuel cycle. Finally, ethanol
from corn produces the largest nitrous oxide emissions across the total fuel
cycle.

Table 7. Fuel Cycle Carbon Dioxide Emissions per Vehicle
Mile Traveled (Grams and Moles)

Fuel Cycle Stage

Gasoline

Methanol From Natural Gas

Ethanol From Corn

Compressed Natural Gas

LPG From Oil and Gas

Grams/

VMT

Moles/

VMT

Grams/

VMT

Moles/

VMT

Grams/

VMT

Moles/

VMT

Grams/

VMT

Moles/

VMT

Grams/

VMT

Moles/

VMT

CO2
From Natural Gas Wells

0.0

0.00

6.3

0.14

0.0

0.00

4.5

0.10

2.9

0.07

Gas
Leaks and Flaresa

3.5

0.08

0.0

0.00

0.0

0.00

0.0

0.00

0.9

0.02

Fertilizer
Manufacture

0.0

0.00

0.0

0.00

57.0

1.30

0.0

0.00

0.0

0.00

N2O,
NOx, CO2 From Fertilizer

0.0

0.00

0.0

0.00

0.0

0.00

0.0

0.00

0.0

0.00

Feedstock
Recovery

10.0

0.23

15.9

0.36

10.8

0.25

6.2

0.14

6.4

0.15

Feedstock
Transmission

8.7

0.20

4.8

0.11

13.7

0.31

0.0

0.00

2.2

0.05

Fuel
Production

47.8

1.09

62.5

1.42

226.1

5.14

5.4

0.12

10.0

0.23

Sequestrationb

0.0

0.00

0.0

0.00

-299.1

-6.80

0.0

0.00

0.0

0.00

Fuel
Distribution

4.9

0.11

23.2

0.53

15.9

0.36

8.7

0.20

5.7

0.13

Compression
or Liquefaction

0.0

0.00

0.0

0.00

0.0

0.00

18.7

0.43

0.0

0.00

Subtotal

74.9

1.71

112.7

2.56

24.4

0.56

43.5

0.99

28.1

0.65

Vehiclec,d,e

272.4

6.19

270.4

6.15

301.1

6.84

204.7

4.65

235.4

5.35

Total

347.3

7.90

383.1

8.71

325.5

7.40

248.2

5.64

263.5

6.00

aAssumes that flared gas is
burned completely to CO2 and water vapor with no methane,
nonmethane organic components, or carbon monoxide.

bSequestration refers to the fixation process of greenhouse
gases emitted (e.g., carbon dioxide and water vapors are sequestered
through photosynthesis).

cDecision Analysis Corporation, “Measurement of Emissions:
Greenhouse Gas Estimates for Alternative Transportation Fuels,”
unpublished final report prepared for the Energy Information Administration
(Vienna, VA, December 1995).

dGreenhouse gas (GHG) emission values from vehicle end-use are
revised.

eThe total GHG emission values are revised because vehicle
end-use values are revised.

CO2 = Carbon dioxide. LPG = Liquefied petroleum gases. N2O
= Nitrous oxide. NOx = Nitrogen oxides. VMT = Vehicle mile
traveled.

Notes: Gasoline refers to unleaded gasoline in this report. • Table
was derived using a vehicle with gasoline efficiency of 30 miles per
gallon. • Emissions from manufacturing the vehicles are not included.
• Nitrogen oxides include primarily nitric oxide and nitrogen
dioxide. One mole of a gas is equal to the amount of substance that
contains as many elementary units (6.023 x 1023 molecules or
atoms) as there are atoms in 12 grams of carbon-12. Normally, emissions are
reported in grams per VMT. However, reporting in moles is preferable
because GHG heat absorption is directly related to the number of molecules
of a gas.

Sources: Derived from GHG emissions spreadsheet provided to the Energy
Information Administration, July 1994. Spreadsheet is an unpublished
revision of Argonne National Laboratory, Center for Transportation
Research, Emissions of Greenhouse Gases From the Use of Transportation
Fuels and Electricity, ANL/ESD/TM-22, prepared by Dr. Mark Delucchi,
Vol. 1 (Argonne, IL, November 1991) and Vol. 2 (Argonne, IL, November
1993). Also see Energy Information Administration, Alternatives to
Traditional Transportation Fuels 1993, EIA/DOE-0585(93) (Washington,
DC, January 1995).

Table
8. Fuel Cycle Water Vapor Emissions per Vehicle Mile Traveled (Grams and
Moles)

Fuel Cycle Stage

Gasoline

Methanol From Natural Gas

Ethanol From Corn

Compressed Natural Gas

LPG From Oil and Gas

Grams/

VMT

Moles/

VMT

Grams/

VMT

Moles/

VMT

Grams/

VMT

Moles/

VMT

Grams/

VMT

Moles/

VMT

Grams/

VMT

Moles/

VMT

CO2
From Natural Gas Wells

0.0

0.00

2.5

0.14

0.0

0.00

1.8

0.10

1.2

0.7

Gas
Leaks and Flaresa

1.4

0.08

0.0

0.00

0.0

0.00

0.0

0.00

0.4

0.02

Fertilizer
Manufacture

0.0

0.00

0.0

0.00

22.9

1.27

0.0

0.00

0.0

0.00

N2O,
NOx, CO2 From Fertilizer

0.0

0.00

0.0

0.00

0.0

0.00

0.0

0.00

0.0

0.00

Feedstock
Recovery

4.0

0.22

6.4

0.36

4.3

0.24

2.5

0.14

2.6

0.14

Feedstock
Transmission

3.5

0.19

1.9

0.11

5.5

0.31

0.0

0.00

0.9

0.05

Fuel
Production

19.2

1.07

25.1

1.39

90.8

5.04

2.2

0.12

4.0

0.22

Sequestrationb

0.0

0.00

0.0

0.00

-120.1

-6.67

0.0

0.00

0.0

0.00

Fuel
Distribution

2.0

0.11

9.3

1.29

6.4

0.36

3.5

0.19

2.0

0.13

Compression
or Liquefaction

0.0

0.00

0.0

0.00

0.0

0.00

7.5

0.42

0.0

0.00

Subtotal

30.1

1.67

45.2

3.29

9.8

0.55

17.5

0.97

11.1

0.63

Vehiclec,d,e

109.4

6.08

232.9

12.94

301.1

16.73

179.3

9.96

135.9

7.55

Total

139.5

7.75

278.1

16.23

310.9

17.28

196.8

10.93

147.0

8.18

aAssumes that flared gas is
burned completely to CO2 and water vapor with no methane,
nonmethane organic components, carbon monoxide, NOx, or N2O.

bSequestration refers to the fixation process of greenhouse
gases emitted (e.g., carbon dioxide and water vapors are sequestered
through photosynthesis). Water vapor sequestration through photosynthesis
is the only process considered in this report. There may be other processes
that merit consideration.

cDecision Analysis Corporation, “Measurement of Emissions:
Greenhouse Gas Estimates for Alternative Transportation Fuels,”
unpublished final report prepared for the Energy Information Administration
(Vienna, VA, December 1995).

dGreenhouse gas (GHG) emission values from vehicle end-use are
revised.

eThe total GHG emission values are revised because vehicle
end-use values are revised.

CO2 = Carbon dioxide. LPG = Liquefied petroleum gases. N2O
= Nitrous oxide. NOx = Nitrogen oxides. VMT = Vehicle mile
traveled.

Notes: Gasoline refers to unleaded gasoline in this report. • Table
was derived using a vehicle with gasoline efficiency of 30 miles per
gallon. • Emissions from manufacturing the vehicles are not included.
• Nitrogen oxides include primarily nitric oxide and nitrogen
dioxide. One mole of a gas is equal to the amount of substance that
contains as many elementary units (6.023 x 1023 molecules or
atoms) as there are atoms in 12 grams of carbon-12. Normally, emissions are
reported in grams per VMT. However, reporting in moles is preferable
because GHG heat absorption is directly related to the number of molecules
of a gas.

Sources: Derived from GHG emissions spreadsheet provided to the Energy
Information Administration, July 1994. Spreadsheet is an unpublished
revision of Argonne National Laboratory, Center for Transportation
Research, Emissions of Greenhouse Gases From the Use of Transportation
Fuels and Electricity, ANL/ESD/TM-22, prepared by Dr. Mark Delucchi,
Vol. 1 (Argonne, IL, November 1991) and Vol. 2 (Argonne, IL, November
1993). Also see Energy Information Administration, Alternatives to
Traditional Transportation Fuels 1993, EIA/DOE-0585(93) (Washington,
DC, January 1995).

Table
9. Fuel Cycle Methane Emissions per Vehicle Mile Traveled (Milligrams and
Millimoles)

Fuel Cycle Stage

Gasoline

Methanol From Natural Gas

Ethanol From Corn

Compressed Natural Gas

LPG From Oil and Gas

mg/

VMT

mmol/

VMT

mg/

VMT

mmol/

VMT

mg/

VMT

mmol/

VMT

mg/

VMT

mmol/

VMT

mg/

VMT

mmol/

VMT

CO2
From Natural Gas Wells

0

0.0

0

0.0

0

0.0

0

0.0

0

0.0

Gas
Leaks and Flaresa

178

11.1

367

22.9

0

0.0

490

30.6

169

10.6

Fertilizer
Manufacture

0

0.0

0

0.0

100

6.3

0

0.0

0

0.0

N2O,
NOx, CO2 From Fertilizer

0

0.0

0

0.0

0

0.0

0

0.0

0

0.0

Feedstock
Recovery

16

1.0

3

0.2

0

0.0

1

0.1

5

0.3

Feedstock
Transmission

9

0.6

30

1.9

16

1.0

0

0.0

2

0.1

Fuel
Production

62

3.9

37

2.3

405

25.3

1

0.1

7

0.4

Sequestration

0

0.0

0

0.0

0

0.0

0

0.0

0

0.0

Fuel
Distribution

4

0.0

30

1.9

20

1.3

40

2.5

7

0.4

Compression
or Liquefaction

0

0.0

0

0.0

0

0.0

27

1.7

0

0.0

Subtotal

269

16.6

467

29.2

541

33.9

559

35.0

190

11.8

Vehicleb,c,d

80

5.4

80

5.4

80

5.4

900

56.3

80

5.4

Total

349

22.0

547

34.6

621

39.3

1,459

91.3

270

17.2

aAssumes that flared gas is
burned completely to CO2 and water vapor with no methane,
nonmethane organic components, carbon monoxide, NOx, or N2O.

bDecision Analysis Corporation, “Measurement of Emissions:
Greenhouse Gas Estimates for Alternative Transportation Fuels,”
unpublished final report prepared for the Energy Information Administration
(Vienna, VA, December 1995).

cGreenhouse gas (GHG) emission values from vehicle end-use are
revised.

dThe total GHG emission values are revised because vehicle
end-use values are revised.

CO2 = Carbon dioxide. LPG = Liquefied petroleum gases. mg =
Milligrams. mmol = Millimoles. N2O = Nitrous oxide. NOx
= Nitrogen oxides. VMT = Vehicle mile traveled.

Notes: Gasoline refers to unleaded gasoline in this report. • Table
was derived using a vehicle with gasoline efficiency of 30 miles per
gallon. • Emissions from manufacturing the vehicles are not included.
• Nitrogen oxides include primarily nitric oxide and nitrogen
dioxide. One mole of a gas is equal to the amount of substance that
contains as many elementary units (6.023 x 1023 molecules or
atoms) as there are atoms in 12 grams of carbon-12. Normally, emissions are
reported in grams per VMT. However, reporting in moles is preferable
because GHG heat absorption is directly related to the number of molecules
of a gas.

Sources: Derived from GHG emissions spreadsheet provided to the Energy
Information Administration, July 1994. Spreadsheet is an unpublished
revision of Argonne National Laboratory, Center for Transportation
Research, Emissions of Greenhouse Gases From the Use of Transportation
Fuels and Electricity, ANL/ESD/TM-22, prepared by Dr. Mark Delucchi,
Vol. 1 (Argonne, IL, November 1991) and Vol. 2 (Argonne, IL, November
1993). Also see Energy Information Administration, Alternatives to
Traditional Transportation Fuels 1993, EIA/DOE-0585(93) (Washington,
DC, January 1995).

Table
10. Fuel Cycle Nitrous Oxide Emissions per Vehicle Mile Traveled
(Milligrams and Millimoles)

Fuel Cycle Stage

Gasoline

Methanol From Natural Gas

Ethanol From Corn

Compressed Natural Gas

LPG From Oil and Gas

mg/

VMT

mmol/

VMT

mg/

VMT

mmol/

VMT

mg/

VMT

mmol/

VMT

mg/

VMT

mmol/

VMT

mg/

VMT

mmol/

VMT

CO2
From Natural Gas Wells

0

0.0

0

0.00

0

0.00

0

0.00

0

0.00

Gas
Leaks and Flaresa

0

0.0

0

0.00

0

0.00

0

0.00

0

0.00

Fertilizer
Manufacture

0

0.0

0

0.00

2

0.05

0

0.00

0

0.00

N2O,
NOx, CO2 From Fertilizer

0

0.0

0

0.00

327

7.41

0

0.00

0

0.00

Feedstock
Recovery

0

0.0

1

0.02

0

0.00

0

0.00

0

0.00

Feedstock
Transmission

0

0.0

0

0.00

1

0.02

0

0.00

0

0.00

Fuel
Production

4

0.1

3

0.07

10

0.20

0

0.00

0

0.00

Sequestration

0

0.0

0

0.00

0

0.00

0

0.00

0

0.00

Fuel
Distribution

0

0.0

1

0.01

1

0.02

0

0.00

1

0.02

Compression
or Liquefaction

0

0.0

0

0.00

0

0.00

1

0.02

0

0.00

Subtotal

4

0.1

5

0.10

341

7.70

1

0.02

1

0.02

Vehicleb,c,d

70

1.6

70

1.60

70

1.60

70

1.60

70

1.60

Total

74

1.7

75

1.70

411

9.30

71

1.62

71

1.62

aAssumes that flared gas is
burned completely to CO2 and water vapor with no methane,
nonmethane organic components, carbon monoxide, NOx, or N2O.

bDecision Analysis Corporation, “Measurement of Emissions:
Greenhouse Gas Estimates for Alternative Transportation Fuels,”
unpublished final report prepared for the Energy Information Administration
(Vienna, VA, December 1995).

cGreenhouse gas (GHG) emission values from vehicle end-use are
revised.

dThe total GHG emission values are revised because vehicle
end-use values are revised.

CO2 = Carbon dioxide. LPG = Liquefied petroleum gases. mg =
Milligrams. mmol = Millimoles. N2O = Nitrous oxide. NOx
= Nitrogen oxides. VMT = Vehicle mile traveled.

Notes: Gasoline refers to unleaded gasoline in this report. • Table
was derived using a vehicle with gasoline efficiency of 30 miles per
gallon. • Emissions from manufacturing the vehicles are not included.
• Nitrogen oxides include primarily nitric oxide and nitrogen
dioxide. One mole of a gas is equal to the amount of substance that
contains as many elementary units (6.023 x 1023 molecules or
atoms) as there are atoms in 12 grams of carbon-12. Normally, emissions are
reported in grams per VMT. However, reporting in moles is preferable
because GHG heat absorption is directly related to the number of molecules
of a gas.

Sources: Derived from GHG emissions spreadsheet provided to the Energy
Information Administration, July 1994. Spreadsheet is an unpublished
revision of Argonne National Laboratory, Center for Transportation
Research, Emissions of Greenhouse Gases From the Use of Transportation
Fuels and Electricity, ANL/ESD/TM-22, prepared by Dr. Mark Delucchi,
Vol. 1 (Argonne, IL, November 1991) and Vol. 2 (Argonne, IL, November
1993). Also see Energy Information Administration, Alternatives to
Traditional Transportation Fuels 1993, EIA/DOE-0585(93) (Washington,
DC, January 1995).

Table
11. Fuel Cycle Carbon Monoxide Emissions per Vehicle Mile Traveled
(Milligrams and Millimoles)

Fuel Cycle Stage

Gasoline

Methanol From Natural Gas

Ethanol From Corn

Compressed Natural Gas

LPG From Oil and Gas

mg/

VMT

mmol/

VMT

mg/

VMT

mmol/

VMT

mg/

VMT

mmol/

VMT

mg/

VMT

mmol/

VMT

mg/

VMT

mmol/

VMT

CO2
From Natural Gas Wells

0

0.0

0

0.0

0

0.0

0

0.0

0

0.0

Gas
Leaks and Flaresa

0

0.0

0

0.0

0

0.0

0

0.0

0

0.0

Fertilizer
Manufacture

0

0.0

0

0.0

119

4.3

0

0.0

0

0.0

N2O,
NOx, CO2 From Fertilizer

0

0.0

0

0.0

0

0.0

0

0.0

0

0.0

Feedstock
Recovery

138

4.9

65

2.3

-2,211

-79.0

43

1.5

62

2.2

Feedstock
Transmission

21

0.8

17

0.6

52

1.9

0

0.0

5

0.2

Fuel
Production

75

2.7

9

0.3

218

7.8

2

0.1

14

0.5

Sequestration

0

0.0

0

0.0

0

0.0

0

0.0

0

0.0

Fuel
Distribution

16

0.6

69

2.5

54

1.9

25

0.9

19

0.7

Compression
or Liquefaction

0

0.0

0

0.0

0

0.0

7

0.3

0

0.0

Subtotal

250

9.0

160

5.7

-1,768

-63.2

77

2.8

100

3.6

Vehicleb,c,d

9,000

321.4

9,000

321.4

9,000

321.4

9,000

321.4

9,000

321.4

Total

9,250

330.4

9,160

327.1

7,232

258.3

9,077

324.2

9,100

325.0

aAssumes that flared gas is
burned completely to CO2 and water vapor with no methane,
nonmethane organic components, carbon monoxide, NOx, or N2O.

bDecision Analysis Corporation, “Measurement of Emissions:
Greenhouse Gas Estimates for Alternative Transportation Fuels,”
unpublished final report prepared for the Energy Information Administration
(Vienna, VA, December 1995).

cGreenhouse gas (GHG) emission values from vehicle end-use are
revised.

dThe total GHG emission values are revised because vehicle
end-use values are revised.

CO2 = Carbon dioxide. LPG = Liquefied petroleum gases. mg =
Milligrams. mmol = Millimoles. N2O = Nitrous oxide. NOx
= Nitrogen oxides. VMT = Vehicle mile traveled.

Notes: Gasoline refers to unleaded gasoline in this report. • Table
was derived using a vehicle with gasoline efficiency of 30 miles per
gallon. • Emissions from manufacturing the vehicles are not included.
• Nitrogen oxides include primarily nitric oxide and nitrogen
dioxide. One mole of a gas is equal to the amount of substance that
contains as many elementary units (6.023 x 1023 molecules or
atoms) as there are atoms in 12 grams of carbon-12. Normally, emissions are
reported in grams per VMT. However, reporting in moles is preferable
because GHG heat absorption is directly related to the number of molecules
of a gas.

Sources: Derived from GHG emissions spreadsheet provided to the Energy
Information Administration, July 1994. Spreadsheet is an unpublished
revision of Argonne National Laboratory, Center for Transportation
Research, Emissions of Greenhouse Gases From the Use of Transportation
Fuels and Electricity, ANL/ESD/TM-22, prepared by Dr. Mark Delucchi,
Vol. 1 (Argonne, IL, November 1991) and Vol. 2 (Argonne, IL, November
1993). Also see Energy Information Administration, Alternatives to
Traditional Transportation Fuels 1993, EIA/DOE-0585(93) (Washington,
DC, January 1995).

Table
12. Fuel Cycle Nitrogen Oxides Emissions per Vehicle Mile Traveled
(Milligrams and Millimoles)

Fuel Cycle Stage

Gasoline

Methanol From Natural Gas

Ethanol From Corn

Compressed Natural Gas

LPG From Oil and Gas

mg/

VMT

mmol/

VMT

mg/

VMT

mmol/

VMT

mg/

VMT

mmol/

VMT

mg/

VMT

mmol/

VMT

mg/

VMT

mmol/

VMT

CO2
From Natural Gas Wells

0

0.0

0

0.0

0

0.0

0

0.0

0

0.0

Gas
Leaks and Flaresa

0

0.0

0

0.0

0

0.0

0

0.0

0

0.0

Fertilizer
Manufacture

0

0.0

0

0.0

476

12.5

0

0.0

0

0.0

N2O,
NOx, CO2 From Fertilizer

0

0.0

0

0.0

210

5.5

0

0.0

0

0.0

Feedstock
Recovery

38

1.0

26

0.7

45

1.2

13

0.3

18

0.5

Feedstock
Transmission

52

1.4

37

1.0

57

1.5

0

0.0

13

0.3

Fuel
Production

90

2.4

380

10.0

560

14.7

6

0.2

16

0.4

Sequestration

0

0.0

0

0.0

0

0.0

0

0.0

0

0.0

Fuel
Distribution

22

0.6

130

3.4

70

1.8

54

1.4

23

0.6

Compression
or Liquefaction

0

0.0

0

0.0

0

0.0

45

1.2

0

0.0

Subtotal

202

5.4

573

15.1

1,418

37.2

118

3.1

70

1.8

Vehicleb,c,d

800

21.1

800

21.1

800

21.1

800

21.1

800

21.1

Total

1,002

26.5

1,373

36.2

2,218

58.3

918

24.2

870

22.9

aAssumes that flared gas is
burned completely to CO2 and water vapor with no methane,
nonmethane organic components, carbon monoxide, NOx, or N2O.

bDecision Analysis Corporation, “Measurement of Emissions:
Greenhouse Gas Estimates for Alternative Transportation Fuels,”
unpublished final report prepared for the Energy Information Administration
(Vienna, VA, December 1995).

cGreenhouse gas (GHG) emission values from vehicle end-use are
revised.

dThe total GHG emission values are revised because vehicle
end-use values are revised.

CO2 = Carbon dioxide. LPG = Liquefied petroleum gases. mg =
Milligrams. mmol = Millimoles. N2O = Nitrous oxide. NOx
= Nitrogen oxides. VMT = Vehicle mile traveled.

Notes: Gasoline refers to unleaded gasoline in this report. • Table
was derived using a vehicle with gasoline efficiency of 30 miles per
gallon. • Emissions from manufacturing the vehicles are not included.
• Nitrogen oxides include primarily nitric oxide and nitrogen
dioxide. One mole of a gas is equal to the amount of substance that
contains as many elementary units (6.023 x 1023 molecules or
atoms) as there are atoms in 12 grams of carbon-12. Normally, emissions are
reported in grams per VMT. However, reporting in moles is preferable
because GHG heat absorption is directly related to the number of molecules
of a gas.

Sources: Derived from GHG emissions spreadsheet provided to the Energy
Information Administration, July 1994. Spreadsheet is an unpublished
revision of Argonne National Laboratory, Center for Transportation
Research, Emissions of Greenhouse Gases From the Use of Transportation
Fuels and Electricity, ANL/ESD/TM-22, prepared by Dr. Mark Delucchi,
Vol. 1 (Argonne, IL, November 1991) and Vol. 2 (Argonne, IL, November
1993). Also see Energy Information Administration, Alternatives to
Traditional Transportation Fuels 1993, EIA/DOE-0585(93) (Washington,
DC, January 1995).

Proceed to Appendix
A