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Technical

Highlights

 Printed on Recycled Paper

United States

Environmental Protection

Agency

Air and Radiation EPA420-F-97-051

December 1997

Office of Mobile Sources

Emission Factors for Locomotives

Estimated Baseline Freight Locomotive Emission

Rates

In support of the rulemaking finalizing the locomotive emission standards, EPA has estimated average emission rates, given in grams per

brake horsepower-hour (g/bhp-hr), for current uncontrolled locomotives.

These estimates are shown in Table 1. It is important to note that there is

significant variability in in-use emission rates. Table 2 shows the range

of emission rates that have been reported for NOx and PM.

The Environmental Protection Agency (EPA) has established emission

standards for oxides of nitrogen (NOx), hydrocarbons (HC), carbon

monoxide (CO), particulate matter (PM) and smoke for newly

manufactured and remanufactured diesel-powered locomotives and

locomotive engines, which have previously been unregulated. Three

separate sets of emission standards have been adopted, with

applicability of the standards dependent on the date a locomotive is first

manufactured. The first set of standards (Tier 0) apply to locomotives

and locomotive engines originally manufactured from 1973 through

2001. The second set of standards (Tier 1) apply to locomotives and

locomotive engines originally manufactured from 2002 through 2004.

The final set of standards (Tier 2) apply to locomotives and locomotive

engines originally manufactured in 2005 and later. To analyze the

environmental benefits expected from these new standards, EPA had to

calculate emission factors for locomotives.
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* Line-haul locomotives over the line-haul duty-cycle

** Switch locomotives over the switch duty-cycle

Conversion to Gram per Gallon Emission Factors

It is often useful to express emission rates as grams of pollutant emitted

per gallon of fuel consumed (g/gal). This can be done by multiplying the

emission rates in Table 1 by a conversion factor. EPA has estimated the

appropriate conversion factor to be 20.8 bhp-hr/gal. These converted

emission factors are shown in Table 3.

Projected Future Emission Factors

With the new national emission standards for both newly manufactured

and remanufactured locomotives originally built after 1972, future

locomotive emission rates are projected to be much lower than the

baseline rates shown above. EPA’s estimates of future emission rates for

Table 1 - Estimated Baseline In-Use Emission Rates

(g/bhp-hr)

H O C C x N M O P

Line-Haul* 0 8 .48 1 0 .2 1 2 3. 0.3

Switch** 1 3 .01 1 4 .8 1 4 7. 0.4

Table 2 - Range of NOx and PM Emission Rates (g/bhp-hr)

L e ine-Haul Cycle Switch Cycl

N M Ox P x N M O P

1 1 0.3-18.2 0 1 .22-0.4 9 6 .2-33. 0.22-0.8

Table 3 - Converted Emission Factors (g/gal)

H O C C x N M O P

Line-Haul 1 6 0 2 0 6. 2 7 7 6.

Switch 2 1 1 3 2 8. 3 2 6 9.
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Tier 0-Tier 2 locomotives are shown in Tables 4-6, respectively. Table 9

gives the expected fleet average emission factors for all locomotives,

which reflects the penetration of the Tier 0-Tier 2 locomotives into the

fleet over time.

Table 4 - Estimated Controlled Emission Rates for

Locomotives Manufactured in 1973-2001 (Tier 0)

H O C C x N M O P

g/bhp

-hr g/gal g/bhp-hr g/gal g/bhp-hr g/gal g/bhp-hr g/gal

Line-Haul 0 0 .48 1 8 1 6 .2 2 6 6. 8 8 . 1 2 7 0 7 .3 6.

Switch 1 1 .01 2 3 1 1 .8 3 6 8. 1 2 2. 2 4 6 0 2 .4 9.

Table 5 - Estimated Controlled Emission Rates for

Locomotives Manufactured in 2002-2004 (Tier 1)

H O C C x N M O P

g/bhp

-hr g/gal g/bhp-hr g/gal g/bhp-hr g/gal g/bhp-hr g/gal

Line-Haul 0 8 .47 9 8 . 1 6 .2 2 7 6. 6 9 . 1 2 3 0 7 .3 6.

Switch 1 1 .01 2 3 1 1 .8 3 9 8. 9 2 . 2 4 0 0 2 .4 9.

Table 6 - Estimated Controlled Emission Rates for

Locomotives Manufactured after 2004 (Tier 2)

H O C C x N M O P

g/bhp

-hr g/gal g/bhp-hr g/gal g/bhp-hr g/gal g/bhp-hr g/gal

Line-Haul 0 4 .26 5 8 . 1 6 .2 2 0 6. 5 3 . 1 7 0 0 6 .1 3.

Switch 0 1 .52 1 3 1 1 .8 3 3 8. 7 2 . 1 1 5 0 3 .2 4.
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Emission Inventory Estimation

Total emissions can be calculated by multiplying the emission factors (in g/gal)

by the fuel consumption rates (in million-gal/yr) to give annual emission rates

(in metric tons per year). This metric estimate can be converted to standard tons

(or short tons) per year, by multiplying it by 1.1.

In the United States, the great majority of fuel consumed by locomotives

each year is used in line-haul freight service. Smaller amounts are also

used in switching and passenger service. EPA’s estimates of these fuel

volumes are shown in Table 7. EPA’s estimates of annual emission rates

calculated from these fuel consumption rates are shown in Table 8.

For More Information

For further information on emission factors for locomotives, please write

to:

U.S. Environmental Protection Agency

Engine Programs and Compliance Division

2565 Plymouth Road

Ann Arbor, MI 48105

Additional documents on locomotive emission standards are available

electronically from the EPA Internet server at:

http://www.epa.gov/OMSWWW/locomotv.htm

or by calling (734) 668-4333.

Table 7 - 1996 Locomotive Fuel Consumption

by Service Category (million gal/year)

National Freight Line-Haul 3,331

National Freight Switching 270

Local and Regional Freight 215

Passenger 133

Table 8 - Estimated 1996 Nationwide Locomotive

Emission Rates (thousand short tons per year)

H O C C x N M O P

4 9 7 1 2 1 1 0 ,20 3
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Table 9 - Fleet Average Emission Factors

For All Locomotives

( ) g/bhp-hr) (g/gal

Y C ear H OC x N M O P CH OC x N M O P

1 2 999 0 2 .5 1 0 .3 1 3 3.3 0 7 .3 1 4 0. 2 7 7. 2 8 76. 6.

2 2 000 0 2 .5 1 6 .3 1 3 3.1 0 7 .3 1 4 0. 2 8 7. 2 8 73. 6.

2 2 001 0 2 .5 1 4 .3 1 3 2.7 0 7 .3 1 4 0. 2 0 7. 2 8 65. 6.

2 2 002 0 2 .5 1 6 .3 1 3 1.9 0 7 .3 1 4 0. 2 8 7. 2 8 48. 6.

2 2 003 0 2 .5 1 2 .3 1 3 1.2 0 7 .3 1 4 0. 2 3 7. 2 8 33. 6.

2 1 004 0 2 .5 1 9 .3 1 3 0.4 0 7 .3 1 4 0. 2 1 7. 2 8 18. 6.

2 0 005 0 2 .5 1 0 .3 9 2 .6 0 4 .3 1 4 0. 2 8 7. 1 6 99. 6.

2 8 006 0 2 .4 1 2 .3 8 1 .9 0 1 .3 1 4 0. 2 6 7. 1 4 85. 6.

2 7 007 0 2 .4 1 1 .3 8 0 .5 0 8 .3 9 4 . 2 0 7. 1 2 77. 6.

2 6 008 0 2 .4 1 9 .3 8 9 .2 0 6 .2 9 4 . 2 5 7. 1 0 72. 6.

2 5 009 0 2 .4 1 9 .3 8 8 .0 0 4 .2 9 4 . 2 3 7. 1 9 68. 5.

2 4 010 0 2 .4 1 4 .3 7 8 .8 0 1 .2 9 4 . 2 0 7. 1 7 63. 5.

2 4 011 0 2 .4 1 4 .3 7 7 .7 0 1 .2 9 4 . 2 1 7. 1 7 61. 5.

2 3 012 0 2 .4 1 2 .3 7 7 .6 0 9 .2 8 4 . 2 5 7. 1 6 58. 5.

2 2 013 0 2 .4 1 0 .3 7 6 .5 0 8 .2 8 4 . 2 9 7. 1 5 55. 5.

2 2 014 0 2 .4 1 7 .3 7 6 .3 0 7 .2 8 4 . 2 4 7. 1 4 53. 5.

2 1 015 0 2 .4 1 6 .3 7 5 .2 0 5 .2 8 4 . 2 0 7. 1 3 51. 5.

2 0 016 0 2 .4 1 4 .3 7 5 .1 0 4 .2 8 4 . 2 5 7. 1 2 48. 5.

2 0 017 0 2 .4 1 4 .3 7 5 .0 0 3 .2 8 4 . 2 5 7. 1 1 46. 5.

2 9 018 0 2 .3 1 4 .3 6 4 .9 0 2 .2 8 4 . 2 4 7. 1 1 44. 5.

2 9 019 0 2 .3 1 4 .3 6 4 .8 0 1 .2 8 4 . 2 4 7. 1 0 42. 5.

2 8 020 0 2 .3 1 5 .3 6 4 .7 0 9 .2 7 4 . 2 3 7. 1 9 40. 4.

2 8 021 0 2 .3 1 5 .3 6 3 .6 0 8 .2 7 4 . 2 3 7. 1 8 38. 4.

2 7 022 0 2 .3 1 6 .3 6 3 .5 0 7 .2 7 4 . 2 4 7. 1 7 36. 4.

2 7 023 0 2 .3 1 6 .3 6 2 .4 0 6 .2 7 4 . 2 4 7. 1 7 34. 4.

2 6 024 0 2 .3 1 7 .3 6 2 .3 0 5 .2 7 4 . 2 5 7. 1 6 32. 4.

2 6 025 0 2 .3 1 9 .3 6 2 .2 0 4 .2 7 4 . 2 7 7. 1 5 30. 4.

2 5 026 0 2 .3 1 0 .3 6 1 .2 0 3 .2 7 4 . 2 0 7. 1 4 29. 4.

2 5 027 0 2 .3 1 2 .3 6 1 .1 0 2 .2 7 4 . 2 2 7. 1 4 27. 4.

2 4 028 0 2 .3 1 4 .3 6 1 .0 0 1 .2 7 4 . 2 6 7. 1 3 25. 4.

2 4 029 0 2 .3 1 6 .3 5 0 .9 0 0 .2 7 4 . 2 0 7. 1 2 24. 4.

2 3 030 0 2 .3 1 8 .3 5 0 .8 0 9 .2 6 4 . 2 3 7. 1 2 22. 4.

2 3 031 0 2 .3 1 0 .3 5 0 .8 0 8 .2 6 4 . 2 7 7. 1 1 20. 4.

2 2 032 0 2 .3 1 3 .3 5 9 .7 0 7 .1 6 4 . 2 2 7. 1 0 19. 4.

2 2 033 0 2 .3 1 6 .3 5 9 .6 0 6 .1 6 4 . 2 6 7. 1 0 17. 4.

2 1 034 0 2 .3 1 8 .3 5 9 .5 0 5 .1 6 4 . 2 1 7. 1 9 16. 3.

2 1 035 0 2 .3 1 4 .3 5 9 .5 0 4 .1 6 4 . 2 3 7. 1 9 15. 3.

2 1 036 0 2 .3 1 2 .3 5 9 .5 0 4 .1 6 4 . 2 9 7. 1 9 14. 3.

2 1 037 0 2 .3 1 9 .3 5 8 .4 0 3 .1 6 4 . 2 3 7. 1 8 14. 3.

2 0 038 0 2 .3 1 7 .3 5 8 .4 0 3 .1 6 4 . 2 7 7. 1 8 13. 3.

2 0 039 0 2 .3 1 4 .3 5 8 .4 0 2 .1 6 4 . 2 2 7. 1 7 13. 3.

2 0 040 0 2 .3 1 1 .3 5 8 .4 0 2 .1 6 4 . 2 6 7. 1 7 12. 3.