nitrogen emissions from u.s. transportation...

Nitrogen Emissions from U.S. Transportation Sources

John Davies Office of Transportation and Air Quality U.S. EPAApril. 9, 2008

Overview

� Transportation Combustion emissions

�NOx

�N2O

� Relative significance of activity trends and emissions controls

� Factors affecting transportation fuel consumption and GHG emissions

� Relationship of NOx / N2O emissions controls to fuel consumption

U.S. NOX Emissions in 2005

Industrial processes, waste disposal & other

7%On-Road Vehicles

43%Stationary Fuel Combustion

38%

Nonroad Vehicles

Source: Inventory of U.S. Greenhouse 12% Gas Emissions and Sinks, 1990-2005

U.S. N2O Emissions in 2005

Other Sources 14%

On-Road VehiclesAgricultural and Soil 7%Management

78% Non-Road Mobile 0.8%

Source: Inventory of U.S. Greenhouse Gas Emissions and Sinks, 1990-2005

1. 0%HFCs

95.1%

1. 0%HFCs

95.1%

Greenhouse Gas Emissions by Gas, 2005

HFCs, PFCs N2O HFCsN2O HFCs

CH4CH47.4%7.4%

CO2

95.1%

CH4 0.1%

7% 3.

CO2

85%

N2O 6.5% 2.2%

CO2

83.8% CO2CO2

95.1%

CH40.1%

7% 3.

CO2

85%

N2O6.5% 2.2%

CO2

83.8%CO2

& SF6 1.9% 3.3%

94.7.%

All U.S. Sources Transportation OnlyAll U.S. Sources Transportation Only


Change in U.S. Vehicle Movement, 1990-2005

Population

GDP

Light-Duty Vehicles

Freight Trucks

Commercial Aircraft

+68.8%

Vehicle Miles Traveled +39%

Ton-Miles +58%

Passenger Miles Traveled

+19%

+55%

0% 10% 20% 30% 40% 50% 60% 70%

Sources: Highway Statistics 2006 Table VM-1, National Transportation Statistics 2005 Table 4-21


Commercial Aircraft

Freight Trucks

Vehicles

+68.8%

GDP

-18.3%

Light-Duty Vehicle Miles Traveled +39%

Ton-Miles +58%


Population +19%

+55%

-37.6% On-Road + Air NOx

Road + Air N20

0% 10% 20% 30% 40% 50% 60% 70%

Sources: Highway Statistics 2006 Table VM-1, National Transportation Statistics 2005 Table 4-21 Inventory of U.S. GHG Emissions and Sinks

Factors Affecting Mobile N2O and NOX tailpipe emissions � Vehicle activity � Fuel consumption � Fuel characteristics � Air-Fuel mixes � Combustion temperatures � Emissions control equipment


Commercial Aircraft

Freight Trucks

Vehicles

+68.8%

NOx

N2O

NOx

N2O

NOx

N2O

Light-Duty Vehicle Miles Traveled +39%

Ton-Miles +58%


-47%

-20.5%

-24%

+1%

+62%

+35.2%

0% 10% 20% 30% 40% 50% 60% 70%


EPA Tier O – B arl EPA Tier 1 – 1990

NOx TrendsU.S. NOx Emissions, 1970 - 2006

Millions of short tons

30.00

25.00

20.00 Other

15.00 Stationary FuelCombustion

10.00 Nonroad Vehicles

5.00 On-Road Vehicles

0.001970 1975 1980 1985 1990 1995 2000 2001 2002 2003 2004 2005 2006

egan e yOxidation Catalyst 1975 to 1980 (cars) 1980s; common until 1984 EPA Tier 2 - 2004

Added advanced emissions and 1980 to 1985 Implemented in cars and LD controls, including elec. Added more advanced

(trucks) trucks Controlled fuel injection & emissions controls, including

ignition timing, EGR and air improved combustion, 3-way catalyst; on-board

NOx reduced 90 percent from diagnostic computer and oxygen injection

sensor NOx reduced 60 percent from Tier 0

Reduced NOX to nitrogen and Tier 0 Nonroad Diesel oxygen; 1.0 g / mil for cars Diesel truck Rule

and bus Locomotive and standards Marine Rule

N2O Trends

600

500

Other400

300

Agricultural and Soil200 Management

100Nonoad MobileOn-Road Vehicles0

1990 1995 2000 2001 2002 2003 2004 2005


Factors Affecting Mobile N2O and NOX tailpipe emissions � Fuel characteristics � Air-Fuel mixes � Combustion temperatures � Use of pollution control equipment � N2O in particular can be formed by

catalytic processes used to controlNOx, CO, and hydrocarbon emissions

Impact of Emissions Control Devices on Transportation N2O Emissions

Transportation GHG Emissions by Gas (Indexed to 1990)

0 0.2 0.4 0.6 0.8

1 1.2 1.4

CO2

N2O

CH4

1975 1980 1990 1992 1994 1996 1998 2000 2002 2004 2006

Oxidation EPA Tier O – EPA Tier 1 EPA Tier 2 – 2004 Catalyst 1975 to 1980 (cars) and 1980 to 1985 (trucks)

Increased per-mile N2O through NOx controls

Reduced N2O emissions rates, but still higher than non-catalyst systems

Reduced N2O emissions by 90 percent relative to Tier 1

Increased N2O emissions rate Rate = Rate =

Rate = 0.0036 g / mi

almost 3X 0.064 g / mi 0.0429 g / mi

Rate = 0.050 g / mile


Total U.S. EmissionsShare of

U.S. Greenhouse Gas Emissions, Mobile Emissions Transportation 2005 (Tg CO2 Eq.) Sector GHGs

i

28% 2 Eq)

72% 2 Eq)

95.6 (Official Estimate)

632.9

566.7

ing 53.1

385.8

i191.8

Transportation Source GHGs Relative to

Source: Inventory of U.S. Greenhouse Gas Emiss ons and Sinks, 1990-2005

Transportation

(2014.0 Tg CO

Other Sectors

(5246.7 Tg CO

International Bunkers - Air and Marine Reported in Inventory, but not included in U.S. Total GHG Estimate or

Passenger Cars

Light-Duty Trucks

Mobile Air Condition

Freight Trucks

Commercial Aircraft 158.1

Buses and Motorcycles 17.1

Other Non-Road 176.2

Lubricants 10.2

Non-Transportation Mob le Sources

Refrigerated Transport 13.6

Included primarily in Industrial sector estimates

0.5% 8.7% 7.9% 0.7%

19.1%

0.8% 2.6%

59.5%

N/A

N/A Transportation Sector Estimate

U.S. Greenhouse Gas Emissions, 1990-2005, Transportation and other U.S. Sources

0

Transportation

Non-Transportation Mobile

Other U.S. Sources

129.1

191.8

6242.0

7260.4

1526.1 1496.0 1539.4 1592.6 1645.2 1680.3 1723.0 1750.4 1785.2 1852.2 1906.7 1879.8 1934.7 1932.5 1987.1 2014.2

1000

2000

3000

4000

5000

6000

7000

8000

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Absolute increase, 1990-2005 Percent Change, 1990-2005Transportation + 487.9 Tg CO2 Eq. Transportation +32.0%

Non-Trans Mobile +62.7 Tg Co2 Eq. Non-Trans Mobile +48.6%

All other sources + 467.8 Tg CO2 Eq. All other sources + 10.2%

Total +1018.4 Tg CO2 Eq. Total (including transport) +16.3% Source: Inventory of U.S. Greenhouse Gas Emissions and Sinks, 1990-2005

Impact of U.S. Fuel Consumption since 1990

US CO2 Emissions from Fossil Fuel Combustion 6000

5000

4000

3000

2000

1000

0

Other U.S. Sources

Non-Transportation Mobile

Transportation

1990 1995 2000 2001 2002 2003 2004 2005

Absolute increase, 1990-2005 Percent Change, 1990-2005 Transportation + 431.9 Tg Transportation +29.4%

Non-Trans Mobile + 62.1 Tg Non-Trans Mobile +48.6%

All other sources + 534.1 Tg All other sources + 11.2%

Total +1027.1 Tg Total (including transport) +21.7%

Per Capita CO2 Emissions from Fossil Fuel Combustion, 1990 and 2005

1990

2005

0 10000 20000 30000 40000 50000

Transportation Other U.S. Sectors

12,956 lbs

14,112 lbs

27,634 lbs

27,237 lbs

41,720lbs

42,762 lbs

1,13

0 lb

s

1,41

2.7

lbs

Non-Trans Mobile

Sources: Inventory of U.S. Greenhouse Gas Emissions and Sinks, 1990-2005

U.S. Census Bureau, Population Division

U.S. GHG Emissions by Gas All Sources 1990 and 2005

6089.5 6000

5000

4000

3000

2000

1000

0

5061.6 1990

2005

609.1 539.3 482.0 468.6 163.089.3

CO2 CH4 N2O HFCs. PFCs and SF6

U.S. Transportation GHG Emissions by Gas, 1990 and 2005

1478.8

1908.1

36.5 67.142.7

0

1000

2000

3000

4000

5000

6000 1990

2005

4.5 N/A 2.3

CO2 CH4 N2O HFCs. (Reflects the phase-in HFCs for ozone-deleting substances)

US Transportation GHGs by Major Source, 1990 and 2005

1199.6 1200

1000

800

600

400

200

0

Light-Duty Freight Trucks Commercial Other * Vehicles Aricraft

1990

2005

69.4%

972.6

227.7 188.1

385.8

158.1

270.5

137.7 14.8%

23.3%

*Other GHGs include emissions from HFCs, which were introduced beginning in the early 1990s to replace ozone depleting substances; increase from 1990 is not meaningful.


Change in Vehicle Movement, 1990-2005

Light-Duty Vehicles

Freight Trucks

Commercial Aircraft

0% 10% 20% 30% 40% 50% 60% 70%

+68.8%

Vehicle Miles Traveled +39%

Vehicle Miles +52%



Change in Activity, Intensity and GHGs, 1990-2005(Passenger Miles and Ton-Miles)

Light-Duty Vehicles

Freight Trucks

Commercial Aircraft

+23.3%

GHGs +69.4%

+14.8%

GHGs /

-10.2% GHGs /PMT

-32.0% GHGs /

PMT

Passenger Miles Traveled +37%

GHGs

Ton-Miles +58%

Passenger Miles Traveled +68.8%

GHGs

ton-mile +7.3%

0% 10% 20% 30% 40% 50% 60% 70%


Light-Duty Vehicles

1990-2005� GHGs up 23.3%; annualized

increase of 1.3% � Passenger Car GHGs decreased

by just under 2% � LD Truck GHGs increased by 72% � Total VMT up 38 percent (mainly

light-duty truck)

2004-2005� GHGs declined very slightly

(0.04%) � Likely impact of fuel prices � Passenger Car GHGs decreased

for the third year in a row � LD Truck GHGs up 2.7 percent,

below avg. annual increase of 3.7 percent from 1990 to 2004

Sources: Inventory of U.S. Greenhouse Gas Emissions and Sinks 1990-2005; Highway Statistics 2005

Tg C

O2

Eq.

GHGs from Light-Duty Vehicles, 1990-2005 800

Passenger Cars 700

600

500 Light-Duty Trucks 400

300

200

100

0 1990 1995 2000 2005

3,000,000

2,500,000

2,000,000

1,500,000

1,000,000

500,000

0

Up 84.4%

Passenger Car VMT

Up 19.2%1,417,823

1,689,965

574,571

1,059,590 Light-Duty Truck VMT

1990 2005

All Light-Duty Vehicles

Light-Duty Vehicles

Sales-Weighted Fuel Economy for New Light-Duty Vehicles and Total LD Fleet, 1975 - 2005

8

4

0 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005

12

16

leet

New Vehicles 22.1 mpg 21.0 mpg

19.7 mpg

15.1 mpg

13.5 mpg

18.9 mpg

Total LD F

Model Year

Sales of New Light-Duty Vehicles, 1975 - 2005

24

20

Mile

s pe

r Gal

lon

12000

10000

8000

6000

4000 Li

Passenger Cars

7,976

ght-Duty Trucks

7,992

Source: Light-Duty Automotive and Fuel

0

2000

Economy Trends: 1975 through 1975 1980 1985 1990 1995 2000 2005 2006, U.S. EPA

Commercial AircraftPercent Change in Aircraft PMT and GHG Emissions, 1990-2005

Perc

enta

ge o

f Ava

ilabl

e Se

ats

Occ

upie

d

80%

Aircraft Passenger Miles

Aircraft GHGs

1990-2005 60%

� GHGs increased 14.8 percent40%

� Passenger miles increased 68 20% percent

� GHGs per passenger mile 0% decreased by 32 percent

-20% � Increased passenger loads1990 1995 2000 2005 � Increased fuel efficiency of

62

7771

60.4 61.2 62.4 64.7 65.4 67.9 69.1 69.9 69.8 69.1 70.3 74.4 72.6

Commercial Aircraft Passenger Load Factor, 1990-2005 new aircraft (~2 percent annually)

80

60 2004-2005 � GHGs increased 6.4 percent

40 � Indicate that we’re approaching a

passenger load ceiling?20

0

1990 1995 2000 2005

Sources: Inventory of U.S. Greenhouse Gas Emissions and Sinks 1990-2005; National Transportation Statistics 2005

Freight Trucks

� GHGs increased 69.4 percent (3.6 percent annualized)

� Medium- and havy-duty trucks have become less energy efficient since the mid-1990s (VIUS data) � Fuel economy of medium trucks (10,000 to 26,000 lbs)

decreased from 8.6 MPG in 1997 to 8.0 mpg in 2002 � FE of heavy trucks (over 26,000 lbs) decreased from 6.1

MPG in 1997 to 5.8 MPG in 2002 � Possible explanations for decreased fuel economy

� Demand for more powerful engines � Impact of congestion � Elimination of mandatory speed limits

GH

G E

mis

sion

s (T

g CO

2 eq

uiv.

)

Freight SourcesGHG Emissions, 1990-2005 Ton-Miles, 1990-2004

450 Trucking

Water

Rail

Pipeline

Air

1,800,000

400 1,600,000

350 1,400,000

300 1,200,000 250

1,000,000 200 800,000 150

600,000 100

400,000 50

200,000 0

0 1990 1995 2000 2005

1990 1992 1994 1996 1998 2000 2002 2004


Air Rail

Change in Freight Activity, Energy Efficiency and GHGs by Mode, 1990 to 2005

85%

75%

65%

55%

45%

35%

25%

15%

5%

-5%

-15%Air Rail Trucking Pipeline

)

ity i ions

ici

Vari

atio

n be

twee

n 19

90 a

nd 2

005

(%

ActivEm ssEnergy Eff ency


Additional Information

Greenhouse Gas Emissions from Transportation and other Mobile Sources http://www.epa.gov/climatechange/emissions/usinventoryreport.html

Inventory of U.S. Greenhouse Gas Emissions and Sinks http://www.epa.gov/climatechange/ emissions/usinventoryreport.html

nitrogen emissions from u.s. transportation...

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