Best Practices Guidebook for 

Greenhouse Gas Reductions in Freight 

Transportation 

Final Report 

Prepared for 

U.S. Department of Transportation 

via Center for Transportation and the Environment 

Prepared by 

H. Christopher Frey and Po-Yao Kuo 

Department of Civil, Construction, and Environmental Engineering 

North Carolina State University 

Raleigh, North Carolina 27695-7908 USA

October 4, 2007 
i 

ACKNOWLEDGMENTS/ DISCLAIMER 

This work is supported by the U.S. Department of Transportation via Center for 

Transportation and the Environment. The authors are responsible for the facts and accuracy 

of the data presented herein. The contents do not necessarily reflect the official views or 

policies of either the U.S. Department of Transportation or the Center for Transportation and 

the Environment at the time of publication. This report does not constitute a standard, 

specification, or regulation. 
ii 

TABLE OF CONTENTS 

EXECUTIVE SUMMARY........................................................................................................ES-1 

ES.1 Background....................................................................................................... ES-1 

ES.2 Study Methodology........................................................................................... ES-1 

ES.3 Identification of Best Practices and Their Estimated Reductions in GHG 

Emissions, Energy Use and Refrigerant Use .................................................... ES-4 

ES.4 Quantitative Assessment Results .................................................................... ES-10 

ES.5 Major Findings................................................................................................ ES-12 

ES.6 Recommendations........................................................................................... ES-13 

1.0 PURPOSE AND BACKGROUND .....................................................................................1 

1.1 Purpose of This Guidebook .................................................................................... 1 

1.2 Background............................................................................................................. 2 

1.3 Using This Guidebook ............................................................................................ 4 

2.0 DEFINITION OF KEY CONCEPTS ..................................................................................7 

2.1 “Best Practices” for Greenhouse Gas Reductions in Freight Transportation ......... 7 

2.2 Modes of Freight Transportation ............................................................................ 7 

2.3 Subgroup................................................................................................................. 9 

2.4 Responsible Parties ................................................................................................. 9 

2.5 Target Parties......................................................................................................... 10 

2.6 Greenhouse Gas Emissions ................................................................................. 10 

2.7 Strategy Types for Reducing Greenhouse Gas Emissions .................................... 10 

2.7.1 Technological Strategies ...............................................................................10 

2.7.2 Operational Strategies...................................................................................10 

2.8 Practice Goals ........................................................................................................11 

2.9 Developmental Status ............................................................................................11 

3.0 METHODOLOGY ............................................................................................................12 

3.1 Literature Review.................................................................................................. 12 

3.2 Reductions in GHG Emissions, and Energy or Refrigerant Use, for Individual 

Best Practices........................................................................................................ 12 

3.3 Quantitative Assessments of Best Practices.......................................................... 14 

3.3.1. Quantifying Cost Implications...................................................................14 

3.3.2 Summarizing and Reporting the Results....................................................15 

3.4 Qualitative Assessments of Best Practices............................................................ 18 

3.5 Aggregated Reductions in GHG Emissions, Energy or Refrigerant Use for 

Multiple Best Practices ......................................................................................... 18 
iii 

3.6 Intermodal Substitution......................................................................................... 22 

4.0. BEST PRACTICES FOR THE TRUCK MODE ..............................................................23 

4.1 Anti-Idling............................................................................................................. 23 

4.1.1 Best Practice 1-1: Off-Board Truck Stop Electrification.........................24 

4.1.2 Best Practice 1-2: Truck-Board Truck Stop Electrification.....................24 

4.1.3 Best Practice 1-3: Auxiliary Power Units................................................24 

4.1.4 Best Practice 1-4: Direct-Fired Heaters...................................................25 

4.1.5 Best Practice 1-5: Direct-Fired Heaters with Thermal Storage 

Units...........................................................................................................25 

4.2 Air Conditioning System Improvement................................................................ 26 

4.2.1 Best Practice 1-6: Enhanced Air Conditioning System I - for 

Direct Emissions ........................................................................................26 

4.2.2 Best Practice 1-7: Enhanced Air Conditioning System II - for 

Indirect Emissions......................................................................................26 

4.2.3 Best Practice 1-8: Alternative Refrigerants - CO2 ...................................26 

4.2.4 Best Practice 1-9: Alternative Refrigerants - HFC-152a.........................27 

4.2.5 Best Practice 1-10: Alternative Refrigerants - HC ..................................27 

4.3 Aerodynamic Drag Reduction .............................................................................. 27 

4.3.1 Best Practice 1-11: Vehicle Profile Improvement I - Cab Top 

Deflector, Sloping Hood and Cab Side Flares ...........................................28 

4.3.2 Best Practice 1-12: Vehicle Profile Improvement II - Closing and 

Covering of Gap between Cab and Trailer or Van, Aerodynamic 

Bumper, Underside Air Baffles, and Wheel Well Covers..........................28 

4.3.3 Best Practice 1-13: Vehicle Profile Improvement III - Trailer or Van 

Leading and Trailing Edge Curvatures ......................................................28 

4.3.4 Best Practice 1-14: Pneumatic Aerodynamic Drag Reduction................28 

4.3.5 Best Practice 1-15: Planar Boat Tail Plates on a Tractor-Trailer .............29 

4.3.6 Best Practice 1-16: Vehicle Load Profile Improvement ..........................29 

4.4 Tire Rolling Resistance Improvement .................................................................. 29 

4.4.1 Best Practice 1-17: Automatic Tire Inflation Systems ............................30 

4.4.2 Best Practice 1-18: Wide-Base Tires .......................................................30 

4.4.3 Best Practice 1-19: Low-Rolling-Resistance Tires..................................30 

4.4.4 Best Practice 1-20: Pneumatic Blowing to Reducing Rolling 

Resistance ..................................................................................................31 

4.5 Hybrid Propulsion ― Best Practice 1-21: Hybrid trucks ................................... 31 

4.6 Weight Reduction ― Best Practice 1-22: Lightweight Materials ...................... 31 
iv 

4.7 Transmission Improvement................................................................................... 32 

4.7.1 Best Practice 1-23: Advanced Transmission ...........................................32 

4.7.2 Best Practice 1-24: Transmission Friction Reduction through 

Low-Viscosity Transmission Lubricants....................................................33 

4.8 Diesel Engine Improvement ................................................................................. 33 

4.8.1 Best Practice 1-25: Engine Friction Reduction through 

Low-Viscosity Engine Lubricants..............................................................33 

4.8.2 Best Practice 1-26: Increased Peak Cylinder Pressures...........................33 

4.8.3 Best Practice 1-27: Improved Fuel Injectors ...........................................34 

4.8.4 Best Practice 1-28: Turbocharged, Direct Injection to 

Improved Thermal Management................................................................34 

4.8.5 Best Practice 1-29: Using Thermoelectric Technology to 

Recovery Waste Heat .................................................................................34 

4.9 Accessory Load Reduction ................................................................................... 35 

4.9.1 Best Practice 1-30: Electric Auxiliaries...................................................35 

4.9.2 Best Practice 1-31: Fuel-Cell-Operated Auxiliaries ................................35 

4.10 Modifications in Driver Operational Practice ―Best Practice 1-32: Truck 

Driver Training Program....................................................................................... 36 

4.11 Alternative Fuel ―Best Practice 1-33: B20 Biodiesel Fuel............................... 36 

4.12 Summary of Potential Best Practices for the Truck Mode.................................... 37 

4.13 Comparisons of Modal GHG Emissions Reductions for the Best Practices ........ 37 

4.14 Quantitative Cost Results for Selected Best Practices.......................................... 50 

5.0. BEST PRACTICES FOR THE RAIL MODE...................................................................52 

5.1 Anti-Idling............................................................................................................. 52 

5.1.1 Best Practice 2-1: Combined Diesel Powered Heating and 

Auto Engine Start/Stop Systems ................................................................52 

5.1.2 Best Practice 2-2: Battery-Diesel Hybrid Switching Locomotive...........53 

5.1.3 Best Practice 2-3: Plug-In Units ..............................................................53 

5.2 Weight Reduction ― Best Practice 2-4: Lightweight Materials ........................ 53 

5.3 Rolling Resistance Improvement ― Best Practice 2-5: Lubrication 

Improvement......................................................................................................... 54 

5.4 Alternative Fuel ― Best Practice 2-6: B20 Biodiesel Fuel for Locomotives .... 54 

5.5 Summary of Potential Best Practices for the Rail Mode ...................................... 54 

5.6 Comparisons of the Modal GHG Emissions Reductions for the Best Practices... 54 

5.7 Quantitative Cost Results for the Selected Best Practices.................................... 58 

6.0. BEST PRACTICES FOR THE AIR MODE .....................................................................60 
v 

6.1 Aerodynamic Drag Reduction .............................................................................. 61 

6.1.1 Best Practice 3-1: Surface Grooves .........................................................61 

6.1.2 Best Practice 3-2: Hybrid Laminar Flow Technology.............................61 

6.1.3 Best Practice 3-3: Blended Winglet.........................................................62 

6.1.4 Best Practice 3-4: Spiroid Tip..................................................................62 

6.2 Air Traffic Management ― Best Practice 3-5 ...................................................... 62 

6.3 Weight Reduction.................................................................................................. 64 

6.3.1 Best Practice 3-6: Airframe Weight Reduction .......................................64 

6.3.2 Best Practice 3-7: Non-Essential Weight Reduction ...............................64 

6.4 Ground Support Equipment Improvement............................................................ 65 

6.4.1 Best Practice 3-8: Ground-Based Equipment as an Alternative 

to Auxiliary Power Units ...........................................................................65 

6.4.2 Best Practice 3-9: Electric or Hybrid Heavy Duty Delivery Trucks .......65 

6.5 Engine Improvement ― Best Practice 3-10: Improved Engine Overall 

Efficiency.............................................................................................................. 65 

6.6 Summary of Potential Best Practices for the Air Mode........................................ 66 

6.7 Comparisons of the Modal GHG Emissions Reductions for the Best Practices... 66 

7.0 BEST PRACTICES FOR THE WATER MODE...............................................................72 

7.1 Propeller System Improvement............................................................................. 72 

7.1.1 Best Practice 4-1: Off-Center Propeller...................................................72 

7.1.2 Best Practice 4-2: Propeller Boss Cap with Fins (PBCF)........................73 

7.1.3 Best Practice 4-3: Auxiliary Free-Rotating Propulsion Device 

behind the Main Propeller..........................................................................73 

7.2 Anti-Idling ― Best Practice 4-4: Shoreside Power for Marine Vessels 

at Ports .................................................................................................................. 73 

7.3 Alternative Fuel ―Best Practice 4-5: B20 Biodiesel Fuel for Ships ................. 74 

7.4 Summary of Potential Best Practices for the Water Mode.................................... 75 

7.6 Comparisons of the Modal GHG Emissions Reductions for the Best Practices... 75 

7.7 Quantitative Cost Results for the Water Mode ..................................................... 75 

8.0 BEST PRACTICES FOR THE PIPELINE MODE...........................................................82 

8.1 Process Control Device Improvement .................................................................. 82 

8.1.1 Best Practice 5-1: Convert Natural Gas Pneumatic Controls to 

Instrument Air ............................................................................................82 

8.1.2 Best Practice 5-2: Replace High-Bleed Natural Gas Pneumatic 

Devices with Low-Bleed Pneumatic Devices............................................83 

8.2 Connecting Method ―Best Practice 5-3: “Hot Tap” Pipeline Connecting 
vi 

Method .................................................................................................................. 83 

8.3 Maintenance.......................................................................................................... 83 

8.3.1 Best Practice 5-4: Transfer Compression ................................................83 

8.3.2 Best Practice 5-5: Inline Inspection.........................................................83 

8.4 Summary of Potential Best Practices for the Pipeline Mode................................ 84 

8.5 Comparisons of the Modal GHG Emissions Reductions for the Best Practices... 84 

8.6 Quantitative Cost Results for the Pipeline Mode.................................................. 84 

9.0 SUMMARY AND COMPARISON OF GHG EMISSIONS REDUCTIONS 

FOR ALL FREIGHT TRANSPORTATION MODES.......................................................89 

9.1 Truck Mode........................................................................................................... 89 

9.2 Rail Mode.............................................................................................................. 92 

9.3 Air Mode............................................................................................................... 97 

9.4 Water Mode........................................................................................................... 97 

9.5 Pipeline Mode ..................................................................................................... 101 

9.6 Intermodal Comparisons..................................................................................... 101 

9.6.1 Total Modal GHG Emissions Reductions................................................101 

9.6.2 Comparisons of Best Practices Whose Costs Are Assessed 

Quantitatively...........................................................................................105 

9.6.3 Intermodal Substitutions ..........................................................................107 

10.0. CONCLUSIONS AND RECOMMENDATIONS...........................................................110 

10.1 Conclusions..........................................................................................................110 

10.2 Recommendations for Future Research Needs....................................................111 

REFERENCES ..................................................................................................... 113 

APPENDIX A. DETAILS OF INPUT DATA, ASSUMPTIONS, AND 

ESTIMATION RESULTS FOR TRUCK MODE BEST PRACTICES ..........................135 

Appendix A.1 Best Practice 1-1: Off-Board Truck Stop Electrification ................... 135 

Appendix A.2 Best Practice 1-2: Truck-Board Truck Stop Electrification ............... 142 

Appendix A.3 Best Practice 1-3: Auxiliary Power Units .......................................... 143 

Appendix A.4 Best Practice 1-4: Direct-Fired Heaters ............................................. 148 

Appendix A.5 Best Practice 1-5: Direct-fired Heaters with Thermal 

Storage Units....................................................................................................... 153 

Appendix A.6 Best Practice 1-6: Enhanced Air Conditioning System I - for 

Direct Emissions ................................................................................................. 154 

Appendix A.7 Best Practice 1-7: Enhanced Air Conditioning System II - for 

Indirect Emissions............................................................................................... 155 

Appendix A.8 Best Practice 1-8: Alternative Refrigerants - CO2 ............................. 156 
vii 

Appendix A.9 Best Practice 1-9: Alternative Refrigerants - HFC-152a ................... 157 

Appendix A.10 Best Practice 1-10: Alternative Refrigerants - HC........................... 158 

Appendix A.11 Best Practice 1-11: Vehicle Profile Improvement I - Cab Top 

Deflector, Sloping Hood and Cab Side Flares .................................................... 159 

Appendix A.12 Best Practice 1-12: Vehicle Profile Improvement II - Closing 

and Covering of Gap between Tractor and Trailer, Aerodynamic Bumper, 

Underside Air Baffles, and Wheel Well Covers.................................................. 160 

Appendix A.13 Best Practice 1-13: Vehicle Profile Improvement III - Trailer or 

Van Leading and Trailing Edge Curvatures........................................................ 161 

Appendix A.14 Best Practice 1-14: Pneumatic Aerodynamic Drag Reduction......... 162 

Appendix A.15 Best Practice 1-15: Planar Boat Tail Plates on a Tractor-Trailer...... 163 

Appendix A.16 Best Practice 1-16: Vehicle Load Profile Improvement................... 164 

Appendix A.17 Best Practice 1-17: Automatic Tire Inflation Systems..................... 165 

Appendix A.18 Best Practice 1-18: Wide-Base Tires................................................ 166 

Appendix A.19 Best Practice 1-19: Low-Rolling-Resistance Tires .......................... 167 

Appendix A.20 Best Practice 1-20: Pneumatic Blowing to Reducing Rolling 

Resistance ........................................................................................................... 168 

Appendix A.21 Best Practice 1-21: Hybrid Trucks ................................................... 169 

Appendix A.22 Best Practice 1-22: Lightweight Materials....................................... 175 

Appendix A.23 Best Practice 1-23: Advanced Transmission.................................... 176 

Appendix A.24 Best Practice 1-24: Transmission Friction Reduction through 

Low-Viscosity Transmission Lubricants............................................................. 177 

Appendix A.25 Best Practice 1-25: Engine Friction Reduction through 

Low-Viscosity Engine Lubricants....................................................................... 178 

Appendix A.26 Best Practice 1-26: Increased Peak Cylinder Pressures ................... 179 

Appendix A.27 Best Practice 1-27: Improved Fuel Injectors.................................... 180 

Appendix A.28 Best Practice 1-28: Turbocharged, Direct Injection to Improved 

Thermal Management ......................................................................................... 181 

Appendix A.29 Best Practice 1-29: Thermoelectric Technology to Recovery 

Waste Heat .......................................................................................................... 182 

Appendix A.30 Best Practice 1-30: Electric Auxiliaries ........................................... 183 

Appendix A.31 Best Practice 1-31: Fuel-Cell-Operated Auxiliaries......................... 184 

Appendix A.32 Best Practice 1-32: Truck Driver Training Program ........................ 185 

Appendix A.33 Best Practice 1-33: B20 Biodiesel Fuel for Trucks.......................... 186 

APPENDIX B. DETAILS OF INPUT DATA, ASSUMPTIONS, AND 

ESTIMATION RESULTS FOR RAIL MODE BEST PRACTICES...............................191 
viii 

Appendix B.1 Best Practice 2-1: Combined Diesel Powered Heating System 

and Auto Engine Start/Stop System.................................................................... 191 

Appendix B.2 Best Practice 2-2: Battery-Diesel Hybrid Switching Locomotive ..... 197 

Appendix B.3 Best Practice 2-3: Plug-in Unit........................................................... 203 

Appendix B.4 Best Practice 2-4: Light Weight Materials ......................................... 210 

Appendix B.5 Best Practice 2-5: Lubrication Improvement ......................................211 

Appendix B.6 Best Practice 2-6: B20 Biodiesel Fuel for Locomotives.................... 212 

APPENDIX C. DETAILS OF INPUT DATA, ASSUMPTIONS, AND 

ESTIMATION RESULTS FOR AIR MODE BEST PRACTICES .................................217 

Appendix C.1 Best Practice 3-1: Surface Grooves.................................................... 217 

Appendix C.2 Best Practice 3-2: Hybrid Laminar Flow Technology........................ 218 

Appendix C.3 Best Practice 3-3: Blended Winglet ................................................... 219 

Appendix C.4 Best Practice 3-4: Spiroid Tip ............................................................ 220 

Appendix C.5 Best Practice 3-5: Air Traffic Management Improvement................. 221 

Appendix C.6 Best Practice 3-6: Airframe Weight Reduction.................................. 222 

Appendix C.7 Best Practice 3-7: Non-Essential Weight Reduction.......................... 223 

Appendix C.8 Best Practice 3-8: Ground-Based Equipment as an Alternative to 

Auxiliary Power Units ........................................................................................ 224 

Appendix C.9 Best Practice 3-9: Electric or Hybrid Heavy Duty Delivery 

Trucks 225 

Appendix C.10 Best Practice 3-10: Improved Engine Overall Efficiency................ 226 

APPENDIX D. DETAILS OF INPUT DATA, ASSUMPTIONS, AND 

ESTIMATION RESULTS FOR WATER MODE BEST PRACTICES ..........................227 

Appendix D.1 Best Practice 4-1: Off-Center Propeller ............................................. 227 

Appendix D.2 Best Practice 4-2: Propeller Boss Cap with Fins ............................... 228 

Appendix D.3 Best Practice 4-3: Auxiliary Free-rotating Propulsion Device 

behind the Main Propellers ................................................................................. 229 

Appendix D.4 Best Practice 4-4: Shoreside Power for Marine Vessels at Ports ....... 230 

Appendix D.5 Best Practice 4-5: B20 Biodiesel Fuel for Ships................................ 231 

APPENDIX E. DETAILS OF INPUT DATA, ASSUMPTIONS, AND 

ESTIMATION RESULTS FOR PIPELINE MODE BEST PRACTICES ......................239 

Appendix E.1 Best Practice 5-1: Convert Natural Gas Pneumatic Controls to 

Instrument Air ..................................................................................................... 239 

Appendix E.2 Best Practice 5-2: Replace High-Bleed Natural Gas Pneumatic 

Devices with Low-Bleed Pneumatic Devices..................................................... 247 

Appendix E.3 Best Practice 5-3: “Hot Tap” Method................................................. 252 
ix 

Appendix E.4 Best Practice 5-4: Transfer Compression ........................................... 257 

Appendix E.5 Best Practice 5-5: Inline Inspection.................................................... 258 

APPENDIX F. FUEL PROPERTIES, CO2 EMISSIONS COEFFICIENTS FOR 

FULES, AND AVERAGE UNIT FUEL COSTS FOR GUIDEBOOK ...........................259 

APPENDIX F.1 Properties of Different Fuels ............................................................. 259 

F.1.1 Definitions of Fuel Properties..................................................................259 

F.1.2 Diesel Fuel ...............................................................................................260 

F.1.3 Jet Fuel.....................................................................................................262 

F.1.4 Biodiesel ..................................................................................................263 

F.1.5 Residual Fuel Oil .....................................................................................263 

F.1.6 Natural Gas ..............................................................................................264 

APPENDIX F.2 CO2 Emissions Coefficients for Different Fuels ............................... 264 

F.2.1 Diesel Fuel ...............................................................................................265 

F.2.2 Jet Fuel.....................................................................................................265 

F.2.3 Biodiesel ..................................................................................................265 

F.2.4 Residual Fuel Oil .....................................................................................265 

F.2.5 Natural Gas ..............................................................................................265 

F.2.6 Comparison of CO2 Emissions Coefficients of Different Fuels ..............266 

APPENDIX F.3 Average Unit Costs for Different Fuels............................................. 266 

F.3.1 Diesel Fuel ...............................................................................................266 

F.3.2 Jet Fuel.....................................................................................................266 

F.3.3 Biodiesel ..................................................................................................266 

F.3.4 Residual Fuel Oil .....................................................................................267 

F.3.5 Natural Gas ..............................................................................................267 

F.3.6 Comparison of Average Unit Cost of Different Fuels..............................267 
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LIST OF TABLES 

Table ES- 1. Potential Best Practices and Their Potential Reductions in Modal GHG 

Emissions and Energy Use................................................................................ ES-5 

Table ES- 2. Summary of Potential GHG Emissions Reductions, Energy Use Reduction, 

Net Savings, Unit Net Savings, and Simple Pay-back Periods of Selected 

Best Practices.................................................................................................. ES-11 

Table 1- 1. Greenhouse Gas Emissions from the Freight Transportation Sector in 2003......... 3 

Table 1- 2. A Scenario of GHG Emissions from Freight Transportation from 2003 to 

2025......................................................................................................................... 4 

Table 2- 1. Truck Classifications by Weight, Number of Axles, and Number of Tires ............ 9 

Table 3- 1. Contribution of Selected Greenhouse Gases to Total Modes ......................... 13 

Table 3- 2. The Format of Standardized Reporting Table....................................................... 16 

Table 3- 3. A Standardized List of Responsible Parties and Target Parties ............................ 19 

Table 3- 4. The Format of Simplified Summary Table ........................................................... 21 

Table 4- 1. List and Description of Potential Best Practices for the Truck Mode................... 38 

Table 4- 2. Summary Table for the Comparison of the Quantitative Cost Results for 

Selected Best Practices for the Truck Mode ......................................................... 51 

Table 5- 1. List and Description of Potential Best Practices for the Rail Mode ..................... 55 

Table 5- 2. Summary Table for the Comparison of the Quantitative Cost Results for 

Selected Best Practices for the Rail Mode............................................................ 59 

Table 6- 1. List and Description of Potential Best Practices for the Air Mode....................... 67 

Table 7- 1. List and Description of Potential Best Practices for the Water Mode .................. 76 

Table 7- 2. Summary Table for the Comparison of the Quantitative Cost Results for A 

Selected Best Practices for the Water Mode ......................................................... 81 

Table 8- 1. List and Description of Potential Best Practices for the Pipeline Mode............... 85 

Table 8- 2. Summary Table for the Comparison of the Quantitative Cost Results for 

Selected Best Practices for the Pipeline Mode ..................................................... 88 

Table 9- 1. Potential Best Practices for the Truck Mode and the Estimated Reductions 

in GHG Emissions and Energy Use...................................................................... 93 

Table 9- 2. Potential Best Practices for the Rail Mode and the Estimated Reductions 

in GHG Emissions and Energy Use...................................................................... 96 

Table 9- 3. Potential Best Practices for the Air Mode and the Estimated Reductions in 

GHG Emissions and Energy Use.......................................................................... 98 

Table 9- 4. Potential Best Practices for the Water Mode and the Estimated Reductions 

in GHG Emissions and Energy Use.................................................................... 100 
xi 

Table 9- 5. Potential Best Practices for the Pipeline Mode and the Estimated 

Reductions in GHG Emissions and Energy Use................................................. 102 

Table 9- 6. Quantitative Summary of Reductions in GHG Emissions, Energy Use, and 

Costs of Selected Best Practices ........................................................................ 106 
xii 

LIST OF FIGURES 

Figure 1- 1 Overview of the Organization and Content of This Guidebook. .............................5 

Figure 4- 1. Reductions in Modal GHG Emissions for the Best Practices for the Truck 

Mode ......................................................................................................................49 

Figure 5- 1. Reductions in Modal GHG Emissions for the Best Practices for the Rail Mode ..57 

Figure 6- 1. Reductions in Modal GHG Emissions for the Best Practices for the Air Mode.....71 

Figure 7- 1. Reductions in Modal GHG Emissions for the Best Practices for the Water 

Mode ......................................................................................................................80 

Figure 8- 1. Reductions in Modal GHG Emissions for Best Practices for the Pipeline Mode..87 

Figure 9- 1. Total Modal 2025 GHG Emissions Reductions Based on Simultaneous 

Implementation of Multiple Best Practices in Each Mode ..................................104 

Figure 9- 2. Magnitudes of the Total Modal 2025 GHG Emissions Reductions Based on 

Simultaneous Implementation of Multiple Best Practices for Each Mode..........105 

Figure 9- 3. Estimated GHG Emissions per Unit of Freight Transport of Each Mode ...........108 
ES-1

EXECUTIVE SUMMARY 

ES.1 Background 

Freight transportation is comprised of five major modes: truck, rail, air, water, and 

pipeline. Freight transportation accounts for approximately 9% of total greenhouse gas (GHG) 

emissions in the United States.1-3 The individual contributions of each of the five freight 

transportation modes to total freight transportation GHG emissions are 60, 6, 5, 13, and 16 

percent, respectively. Energy use for all modes could increase by 75% from 2003 to 2030, 

based on a long-term energy trend scenario in the Energy Information Administration’s Annual 

Energy Outlook 2006.

4

 Since energy use for freight transportation is expected to increase 

significantly in the next 25 years, and because GHG emissions are largely based on energy use, 

GHG emissions will also increase significantly. 

Governments and the freight industry recognize the need for solutions to meet future 

challenges for GHG emissions reductions.2,5 There are a growing number of technological and 

operational strategies, existing or developing, that could reduce GHG emissions. Disseminating 

information regarding these technological and operational strategies can facilitate decision 

making to achieve reductions in energy use and GHG emissions. This guidebook presents a 

survey of potential best practices for reducing energy use and GHG emissions in freight 

transportation. The report characterizes each potential best practice in order to serve the 

information needs of decision makers and responsible parties. 

ES.2 Study Methodology

The methodology includes reviewing literature to identify best practices, assessing 

maximum reductions in GHG emissions and energy or refrigerant use for individual best 

practices and of multiple best practices, assessing cost savings, and summarizing and reporting 

assessment results. The GHG emissions of interest here are CO2, methane (CH4), and 

refrigerants. CO2 has a global warming potential (GWP) of 1. Methane has a global warming 

potential of 21. The currently widely used refrigerant, HFC-134a, has a GWP of 1,300. 

However, methane and refrigerant are emitted in smaller mass amounts than CO2. 

A potential best practice is an existing or developing strategy or technology that is 

expected to lead to reductions in energy use, refrigerant use, and greenhouse gas emissions. 

Potential best practices are identified based on literature review. The potential best practices are 

categorized by subgroups based on the factors that the practices can improve, or the technologies 

that vehicles or devices may apply, to reduce GHG emissions.
ES-2

The potential reduction in GHG emission and energy or refrigerant use for each potential 

best practice is estimated based on what may be achievable by 2025. Reductions are compared 

to estimated 2025 GHG emissions if none of these best practices are adopted. While the scope 

of this work includes estimate of GHG emissions, energy use, and refrigerant use, in most cases, 

significant reductions in GHG emissions achievable with potential best practices are associated 

with reductions in energy use. . 

The potential per-device reductions in GHG emissions, energy or refrigerant use for an 

individual potential best practice are estimated based on the results of literature review. 

Per-device reductions for each potential best practice, except for alternative fuel strategies, are 

estimated based on the differences in per-device emissions, energy use or refrigerant use with 

and without the use of this potential best practice. Reductions for alternative fuel strategies are 

estimated based on life cycle inventories. Each practice may only be applicable to a fraction of 

all devices within a mode. 

Identified potential best practices are categorized with respect to developmental status: 

commercially available, pilot tests, and new concepts. Commercially available systems can be 

purchased or implemented now. Potential best practices based on pilot tests may be available 

within five to ten years, whereas those that are new concepts may require research, development, 

and demonstration that could vary in duration. An assumption is made that each potential best 

practice reaches a best estimate of maximum market penetration by 2025. Technical, practical, 

and cost barriers are not quantified here. Actual market penetration may be lower than 

estimated. However, the estimates provide a useful upper bound as to what might be achieved 

if adoption of such practices is encouraged. 

Potential best practices are grouped by subgroup. Subgroups are based on similar 

objectives or methods. An example is aerodynamic drag reduction. Aggregate reductions in 

modal GHG emissions and energy or refrigerant use for a subgroup are estimated based on a 

simple linear combination of the reductions for multiple potential best practices within the 

subgroup, except in some situations. In some cases, two or more practices within a subgroup 

are mutually exclusive because they cannot be used simultaneously. In the case of mutual 

exclusion, the practice with the highest estimated reduction is used in the estimate of total 

reductions for the subgroup. For example, three alternative refrigerants for air conditioning 

systems that could be used as potential best practices are mutually exclusive. Only one 

refrigerant can be used in an air conditioning system. CO2 is chosen here because it has the 

lowest GWP compared to the other candidate refrigerants and its potential reductions in modal 

GHG emissions are the highest. Thus, the estimates do not double count mutually exclusive 

practices. For some potential best practices, it is possible that they could be implemented 
ES-3

simultaneously but that they may interact. Thus, the total reduction may not be a simple linear 

combination of the reductions of each practice. An example would be several practices that 

reduce aerodynamic drag of a truck. However, there is a lack of data upon which to quantify 

the overall reduction associated with interactions among multiple practices within a subgroup. 

Therefore, these interactive effects are not quantified. The linear combination may tend to 

overestimate the maximum possible reduction for the subgroup. Such situations are noted. 

For all potential best practices, a quantitative estimate is made of the potential reductions 

in energy use, GHG emissions, and refrigerant leakage. However, for many potential best 

practices, inadequate data are available for assessment of cost. Quantitative assessments for 

cost effectiveness are performed, where sufficient data are available for: practice cost; energy 

or refrigerant cost reduction; and total net cost savings. Total net cost savings is the difference 

between annual energy or refrigerant cost savings and the annualized costs, the latter of which 

include levelized capital costs and annual operation and maintenance costs. Net savings per unit 

of GHG emissions reductions are estimated by normalizing total net savings with respect to 

GHG emissions reductions. A positive value of net savings means that the practice will pay for 

itself over some period of time, whereas a negative value means that the annualized costs exceed 

savings associated with reductions in energy use or refrigerant use. A standardized reporting 

table, which includes three parts, is used to report the quantitative characteristics and assessment 

results of individual potential best practices. The first part summarizes characteristics, 

including: practice name; applicable mode type; subgroup; responsible parties; target parties; 

targeted GHGs; strategy type; practice goals; developmental status; and practice summary The 

second part includes: the magnitude of transport activity for the whole mode; the magnitude of 

transport activity to which the practice is applicable; total annual modal reductions in GHG 

emissions, energy use, and refrigerant use; and reductions of each per unit of freight transport. 

The third part includes: annualized costs; energy or refrigerant costs savings; net savings per 

unit of reductions in GHG emissions and energy or refrigerant use; and simple payback periods. 

The effects of the potential best practices where cost quantitative data are not available 

are discussed qualitatively in a structured approach. A simplified summary table, which 

includes four parts, is used to report the qualitative assessment results. The first part is 

technological information, including: practice name; applicable mode type; subgroup; 

responsible parties; target parties; target GHGs of interest; strategy type; practice goals for GHG 

emissions reduction; developmental status; and a brief summary of the practice. The second 

part includes quantitative estimates of the potential modal reductions in GHG emissions, energy 

use or refrigerant use for individual potential best practices. The third part is cost information, 

which can be any available knowledge, such as assumptions regarding capital cost, cost 
ES-4

premiums or cost savings, and retail price impacts reported in the literature. The fourth part 

describes the benefits and the drawbacks of the practice. 

ES.3 Identification of Potential Best Practices and Their Estimated Reductions in GHG 

Emissions, Energy Use and Refrigerant Use 

A total of 59 strategies have been identified as potential best practices in freight 

transportation. There are 33, 6, 10, 5, and 5 potential best practices for the truck, rail, air, water, 

and pipeline modes, respectively. Over half of the total number of potential best practices is for 

the truck mode. Reduction in energy use is the basis of GHG emissions reductions for 51 of the 

potential best practices. One practice can reduce direct GHG emissions but increases direct 

energy use. For 3 practices, life cycle GHG emissions are reduced but life cycle energy use 

may be increased. Four strategies, which are potential best practices for the air conditioning 

system improvement subgroup for the truck mode, can reduce GHG emissions by reducing 

refrigerant leakage rate or by using low global-warming-potential refrigerants. Table ES-1 

summarizes key aspects of the characteristics and potential reductions in modal GHG emissions 

and energy use for individual potential best practices. 

The magnitude of aggregate reductions in 2025 for each subgroup is also summarized in 

Table ES-1. The reported reductions are the difference between 2025 GHG emissions (or 

energy use) with and without use of potential best practices in a subgroup. For cases of mutual 

exclusivity within a subgroup, one estimate of the reductions is given. For cases of multiple 

practice interaction, a simple linear combination of the reductions is applied, which may tend to 

overestimate the maximum possible reduction for the subgroup. 

The potential total GHG emissions reduction by 2025 for all 59 potential best practices is 

estimated as 4.6×108

 tons CO2 eq. If no potential best practices are implemented, the total 

GHG emissions by 2025 for the freight transportation are estimated to be 11.0×108 tons CO2 eq. 

If all potential best practices are implemented, the total GHG emissions for the freight 

transportation are estimated to be 6.4×108

 tons CO2 eq. Thus, total estimated GHG emissions 

reductions by 2025 for all potential best practices, 4.6×108 tons CO2 eq., is estimated to be 42% 

of 2025 GHG emissions if no potential best practice is implemented. Most of these estimated 

reductions (4.4×108 tons CO2 eq. out of a total reduction of 4.6×108 tons CO2 eq.) are attributed 

to an estimated energy use reduction of 4.5×1015 BTU. A small portion of these estimated 

reductions (0.18×108

 tons CO2 eq.) is attributed to refrigerant leakage rate reduction or use of 

low global-warming-potential refrigerants. 
ES-5

Table ES- 1. Potential Best Practices and Their Potential Reductions in Modal GHG 

Emissions and Energy Use 

Mode 

Subgroupa I.D. 

No. 

Brief Name of Potential Best 

Practice 

Developmental Statusb

Potential Reduction in Modal 

GHG Emissionsc

Potential Reduction in Modal 

Energy Used

The Magnitude of Aggregate 

GHG Emissions Reductions in 

2025 for Each Subgroup 

(106 Tons CO2 eq.)

e

The Magnitude of Aggregate 

Energy Use Reduction in 2025 

for Each Subgroup 

(1015 BTU)

f

1-1 Off-Board Truck Stop 

Electrification C L L 

1-2 Truck-Board Truck Stop 

Electrification C L L 

1-3 Auxiliary Power Units C M M 

1-4 Direct-Fired Heaters C M M 

Anti-Idling (E) 

1-5 Direct-Fired Heaters with 

Thermal Storage Units P M M 

15.0 0.19 

1-6 Enhanced Air Conditioning 

System I - for Direct Emissions P L -

1-7 

Enhanced Air Conditioning 

System II - for Indirect 

Emissions 

C L L 

1-8 Alternative Refrigerants - CO2 N M -

1-9 Alternative Refrigerants - 

HFC-152a N M -

Truck 

Air Conditioning 

System Improvement 

(B) 

1-10 Alternative Refrigerants - HC N M -

19.2g

 0.02 

Continued on next page 

a

 Some best practices within a subgroup are mutually exclusive or have interactions. (E) = mutually exclusive within a 

subgroup; (I) = interaction within a subgroup; and (B) = some best practices are mutually exclusive and some have 

interactions within a subgroup. b

 Developmental status: N = new concepts; P = pilot tests; C = commercially available systems. New concepts include 

basic research activities, applied research activities, and experiments at laboratory level. Pilot tests include testing 

prototype vehicles and demonstration projects. Commercially available systems can be purchased or implemented now. c

 Potential reductions in modal GHG emissions are estimated based on the difference in 2025 modal emissions with and 

without the selected best practice divided by the total modal emissions if no best practices are implemented. These 

potential reductions are categorized into three ranges: low (L) (0% - 1%), medium (M) (1% - 4%), and high (H) (> 4%). d

 Potential reductions in modal energy use are estimated based on the difference in 2025 modal energy use with and without 

the selected best practice divided by the total modal energy use if no best practices are implemented. These potential 

reductions are categorized into four ranges: low (L) (0% - 1%), medium (M) (1% - 4%), high (H) (> 4%), and negative 

(NG) (energy increases). “-” refers to no reduction. e

 These reductions are estimated based on the difference between 2025 modal emissions with and without implementation of 

the representative best practices of the subgroup. As noted in the text, only one best practice is selected if multiple 

practices within a subgroup are mutually exclusive. For cases of multiple interactions, a simple linear combination of the 

reductions is applied. f

 These reductions are estimated based on the difference between 2025 modal energy use with and without implementation of 

the representative best practices of the subgroup. g

 Of the reported value, 17.8×106 tons CO2 eq. aggregated GHG emission reduction is attributed to refrigerant leakage rate 

reduction or use of low global-warming-potential refrigerants. 
ES-6

Table ES-1. Continued Mode 

Subgroupa I.D. 

No. 

Brief Name of Potential Best 

Practice 

Developmental Statusb

Potential Reduction in Modal 

GHG Emissionsc

Potential Reduction in Modal 

Energy Used

The Magnitude of Aggregate 

GHG Emissions Reductions 

in 2025 for Each Subgroup 

(106 Tons CO2 eq.)

e

The Magnitude of Aggregate 

Energy Use Reduction in 

2025 for Each Subgroup 

(1015 BTU)

f

1-11 Cab Top Deflector, Sloping 

Hood and Cab Side Flares C M M 

1-12 

Closing and Covering of Gap 

Between Tractor and Trailer, 

Aerodynamic Bumper, 

Underside Air Baffles, and 

Wheel Well Covers 

C M M 

1-13 Trailer Leading and Trailing 

Edge Curvatures C M M 

1-14 Pneumatic Aerodynamic Drag 

Reduction N M M 

1-15 Planar Boat Tail Plates on a 

Tractor-Trailer N M M 

Aerodynamic Drag 

Reduction (B) 

1-16 Vehicle Load Profile 

Improvement C L L 

66.6 0.83 

1-17 Automatic Tire Inflation Systems C L L 

1-18 Wide-base Tires C M M 

1-19 Low-Rolling-Resistance Tires C M M 

Tire Rolling 

Resistance 

Improvement (E) 1-20 Pneumatic Blowing to Reducing 

Rolling Resistance N L L 

28.3 0.35 

Hybrid Propulsion 1-21 Hybrid trucks N M M 24.5 0.30 

Weight Reduction 1-22 Lightweight Materials P H H 33.3 0.41 

1-23 Advanced Transmission P L L 

Truck 

Transmission 

Improvement (I) 1-24 

Transmission Friction Reduction 

through Low-Viscosity 

Transmission Lubricants 

C L L 13.6 0.17 

1-25 

Engine Friction Reduction 

through Low-Viscosity Engine 

Lubricants 

C M M 

1-26 Increased Peak Cylinder 

Pressures C M M 

1-27 Improved Fuel Injectors P H H 

1-28 Turbocharged, Direct Injection to 

Improved Thermal Management C L L 

Diesel Engine 

Improvement (I) 

1-29 Thermoelectric Technology to 

Recovery Waste Heat N H H 

118.3 1.47 

Accessory Load 1-30 Electric Auxiliaries C M M 

Reduction (B) 1-31 Fuel-Cell-Operated Auxiliaries N H H 39.6 0.49 

Driver Operation 

Improvement 1-32 Truck Driver Training Program C M M 22.3 0.28 

Truck 

Alternative Fuel 1-33 B20 Biodiesel Fuel for Trucks C H NG 30.8 -0.37 

Total for the Truck 

Mode 411.5 4.14 

Continued on next page 
ES-7

Table ES-1. Continued Mode 

Subgroupa I.D. 

No. 

Brief Name of Potential Best 

Practice 

Developmental Statusb

Potential Reduction in Modal 

GHG Emissionsc

Potential Reduction in Modal 

Energy Used

The Magnitude of Aggregate 

GHG Emissions Reductions 

in 2025 for Each Subgroup 

(106 Tons CO2 eq.)

e

The Magnitude of Aggregate 

Energy Use Reduction in 

2025 for Each Subgroup 

(1015 BTU)

f

Anti-Idling (E) 2-1 

Combined Diesel Powered 

Heating System and Auto Engine 

Start/stop System 

P M M 3.4 0.04 

 2-2 Battery-Diesel Hybrid Switching 

Locomotive C M M 

 2-3 Plug-In Units C L L 

Weight Reduction 2-4 Light Weight Materials C H H 3.0 0.04 

Rolling Resistance 

Improvement 2-5 Lubrication Improvement P M M 2.6 0.03 

Rail 

Alternative Fuel 2-6 B20 Biodiesel Fuel for 

Locomotives N H NG 3.5 -0.04 

Total for the Rail 

Mode 12.6 0.07 

3-1 Surface Grooves P M M 

3-2 Hybrid Laminar Flow 

Technology N H H 

3-3 Blended Winglet C M M 

Aerodynamic Drag 

Reduction (E) 

3-4 Spiroid Tip P M M 

5.7 0.06 

Air Traffic 

Management 3-5 Air traffic Management 

Improvement N H H 3.5 0.04 

3-6 Airframe Weight Reduction N M M Weight Reduction 3-7 Non-Essential Weight Reduction N L L 1.8 0.02 

3-8 

Ground-Based Equipment as an 

Alternative to Auxiliary Power 

Units 

Ground Support P 

Equipment 

Improvement 3-9 Electric or Hybrid Heavy Duty 

Delivery Trucks P 

M M 1.7 0.02 

Air 

Engine Improvement 3-10 Improved Engine Overall 

Efficiency C H H 7.7 0.08 

Total for the Air 

Mode 20.4 0.21 

4-1 Off-Center Propeller C M M 

4-2 Propeller Boss Cap with Fins C M M Propeller System 

Improvement (E) 4-3 

Auxiliary Free-Rotating 

Propulsion Device behind the 

Main Propeller 

C M M 

3.7 0.04 

Anti-Idling 4-4 Shoreside Power for Marine 

Vessels at Ports P L NG 0.2 > -0.01 

Water 

Alternative Fuel 4-5 B20 Biodiesel Fuel for Ships N M NG 1.5 -0.02 

Total for the Water 

Mode 5.3 0.03 

Continued on next page 
ES-8

Table ES-1. Continued Mode 

Subgroupa I.D. 

No. 

Brief Name of Potential Best 

Practice 

Developmental Statusb

Potential Reduction in Modal 

GHG Emissionsc

Potential Reduction in Modal 

Energy Used

The Magnitude of Aggregate 

GHG Emissions Reductions 

in 2025 for Each Subgroup 

(106 Tons CO2 eq.)

e

The Magnitude of Aggregate 

Energy Use Reduction in 

2025 for Each Subgroup 

(1015 BTU)

f

5-1 Convert Natural Gas Pneumatic 

Controls to Instrument Air C L L 

Process Control 

Device Improvement 5-2 

Replace High-Bleed Natural Gas 

Pneumatic Devices with 

Low-Bleed Pneumatic Devices 

C L L 

1.4 < 0.01 

Connecting Method 5-3 “Hot Tap” Method C M L 2.5 < 0.01 

5-4 Transfer Compression C L L 

Pipeline 

Maintenance 5-5 Inline Inspection C M L 1.8 < 0.01 

Total for the Pipeline 

Mode 5.7 0.01 
ES-9

Within each mode, multiple potential best practices can be applied simultaneously to 

achieve total 2025 modal GHG emissions reductions (compared to projected emissions if no 

potential best practices are used) of 57, 19, 34, 4, and 4 percent for the truck, rail, air, water, and 

pipeline modes, respectively. In making these estimates, we do not double count mutually 

exclusive potential best practices and we consider linear combinations of reductions for multiple 

potential best practices that could synergistically interact. 

The potential best practices also vary substantially in terms of their potential percentage 

reductions in modal GHG emissions. The variations in reductions among individual practices 

range from 0.2 to 5.5 percent for the truck mode, 0.6 to 5.5 percent for the rail mode, 1.0 to 13.0 

percent for the air mode, 0.2 to 3.0 percent for the water mode, and 0.1 to 1.9 percent for the 

pipeline mode. The average reductions for a potential best practice are 2.2, 3.4, 2.3, 1.6 and 1.3 

percent for the truck, rail, air, water, and pipeline modes, respectively. 

There is also substantial variability among the potential best practices in terms of their 

contributions to percentage decreases or increases in modal energy use. The range of these 

changes among individual potential best practices are from a 4.3 percent increase to a 5.7 percent 

decrease for the truck mode, a 5.3 percent increase to a 4.8 percent decrease for the rail mode, a 

1.0 to 13.0 percent decrease for the air mode, a 1.3 percent increase to a 3.0 percent decrease for 

the water mode, and a 0.02 to 0.5 percent decrease for the pipeline mode. The averages of these 

changes are 1.8, 1.5, 2.3, 1.0, and 0.2 percent for the truck, rail, air, water, and pipeline modes, 

respectively. Several potential best practices in the truck, rail, and water modes are based on 

alternative fuels. Alternative fuel strategies consume more energy than conventional petroleum 

fuel, based on life cycle inventories. Thus, the average percentage reductions in modal energy 

use among all potential best practices for truck, rail and water, which range from 1.0 to 1.8 

percent, are significantly smaller than their average percentage reductions in modal GHG 

emissions, which range from 1.6 to 3.4 percent. 

The magnitude of the estimated potential GHG emissions reductions for the truck mode 

in 2025, which is 410×106

 tons CO2 eq., is significantly higher than for any of the other four 

modes, which range from approximately 5×106 to 20×106 tons CO2 eq. The truck mode is 

estimated to contribute 66 percent of freight transportation GHG emissions in 2025 if none of the 

potential best practices are adopted. The total GHG emissions of this mode in 2025 are 

estimated to increase 67 percent over 2003 levels. If all identified potential best practices are 

implemented aggressively, 2025 GHG emissions could be reduced by as much as 28 percent 

compared to 2003 levels. Of other modes, each of the other four modes is estimated to 

contribute 12 percent or less to total freight GHG emissions in 2025. If no potential best 

practices are implemented, modal GHG emissions in 2025 from the rail, air, water, and pipeline 
ES-10

modes are estimated to increase 49, 65, 28, and 15 percent, respectively, compared to 2003 levels. 

If all identified potential best practices are implemented aggressively, 2025 GHG emissions 

could increase by 20, 8, 22, and 9 percent, respectively, compared to 2003 levels, which is 

smaller than the increase if no potential best practices are implemented. In sum, if all identified 

practices are implemented aggressively, the possible net decrease in total freight transportation 

GHG emissions from 2003 to 2025 is 11%, even if energy use increases as currently projected. 

The magnitude of the estimated potential energy use reduction for the truck mode in 2025 

is also significantly higher than for the other four modes. If no potential best practices are 

implemented, the truck mode is estimated to consume 70 percent of freight transportation energy 

in 2025. The truck mode energy use in 2025 is estimated to increase by 67 percent compared to 

2003 levels. If all identified potential best practices are implemented aggressively, 2025 energy 

use could be reduced by as much as 12 percent compared to 2003 levels. Each of the other four 

modes are estimated to consume 12 percent or less of total freight energy consumption in 2025 

If no best practices are implemented, total modal energy use in 2025 from the rail, air, water, and 

pipeline modes are estimated to increase 49, 65, 28, and 15 percent, respectively, compared to 

2003 levels. If all identified potential best practices are implemented aggressively, these 

increases in energy use are estimated at 36, 8, 25, and 13 percent, respectively, compared to 2003 

levels. These energy use increases with the implementation of all identified potential best 

practices are significantly less than those energy use increases without the implementation of all 

identified potential best practices. 

ES.4 Quantitative Assessment Results 

To date, sufficient information has been obtained to assess the costs of 13 potential best 

practices quantitatively. Table ES-2 summarizes: reductions in GHG emissions and energy 

use; net savings; net savings per unit of GHG emissions reduction; and net savings per unit of 

energy use reduction, and simple pay-back periods of selected potential best practices. 

These 13 potential best practices vary substantially in terms of annual reductions in 

modal GHG emissions and energy use within their individual modes. Four best practices for 

the truck mode, which include auxiliary power units, direct-fired heaters, hybrid trucks, and B20 

biodiesel, have the potential to achieve substantial GHG emissions reductions (8×106

 ton CO2

eq./year or more). Two best practices for the truck mode, auxiliary power units and hybrid, also 

have the potential to reduce energy use substantially, by 185×1012 BTU or more. 

These 13 potential best practices vary substantially regarding their cost- effectiveness and 

simple pay-back periods. The most cost-effective best practices are: plug-in units for the rail 

mode; direct-fired heater for the truck mode; and combined diesel powered heating system and 
ES-11

Table ES- 2. Summary of Potential GHG Emissions Reductions, Energy Use Reduction, 

Net Savings, Unit Net Savings, and Simple Pay-back Periods of Selected Best 

Practicesa

Mode I.D. 

No. Practice Name 

Modal GHG Emission 

Reduction 

(106 ton CO2 eq./year) 

Modal Energy Use 

Reduction 

(1012 BTU /

year)

Net Saving 

($106/year) 

Net Saving per Unit of 

GHG Emission Reduction 

($/ton CO2 eq.) 

Net Saving per Unit of 

Energy Use Reduction 

($/106 BTU) 

Simple Pay- back period 

(year) 

1-1 Off-Board Truck Stop 

Electrification 2.4 27 330 138 12 N/Ac

1-3 Auxiliary Power Units 15 185 440 29 2.3 3.2 

1-4 Direct Fire Heaters 7.6 94 1350 178 14 0.6 

1-21 Hybrid Trucks 24.5 300 3190 130 11 2.1 

Truck 

1-33 B20 Biodiesel for Trucks 30.8 -370 -3300 -108 N/Ab N/Ad

2-1 

Combined Diesel Powered 

Heating System and Auto 

Engine Start/stop System 

2.3 29 390 167 14 2.1 

2-2 Battery Diesel Hybrid 

Switching Locomotive 1.1 14 70 65 5.2 5.5 

2-3 Plug-In Unit 0.4 4 135 364 38 0.8 

Rail 

2-6 B20 Biodiesel for 

Locomotives 3.5 -42 -380 -109 N/Ab

 N/Ad

Water 

4-5 B20 Biodiesel for Ships 1.5 -18 -180 -120 N/Ab N/Ad

5-1 

Convert Natural Gas 

Pneumatic Controls to 

Instrument Air 

0.7 1 12 18 9.6 0.3 

5-2 

Replace High-Bleed Natural 

Gas Pneumatic Devices with 

Low-Bleed Pneumatic 

Devices 

Pipeline 

0.8 2 13 18 8.8 0.9 

5-3 “Hot Tap” Method 2.5 5 40 16 7.8 0.2 a

 These assessments are based on the assumptions that these best practices reach their potential 

maximum market shares in 2025. 

b

 This practice has no energy use reduction due to an increase in energy use, and it has no net saving due 

to high annualized cost and no energy cost saving. c

 There is no pay-back period for this best practice because there is no initial capital cost to users. 

d

 There is no pay-back period for this best practice because there is no net saving.
ES-12

auto engine start/stop system for the rail mode. The least cost-effective best practices are B20 

biodiesel for the truck, rail and water modes. Five best practices have simple pay-back periods 

of less than 1 year. 

From a national policy perspective, consideration of the potential magnitude of 

reductions is important. From an individual owner or operator perspective, consideration of 

cost savings and cost effectiveness may be more important. 

Even larger percentage reductions are possible if intermodal shifts, such as from truck to rail, are 

possible. The complete rail-truck intermodal shift could reduce GHG emissions for the truck 

mode by 85 percent, if no potential best practices are implemented for either mode. Whether 

intermodal shift is possible depends on site-specific characteristics. 

ES.5 Major Findings 

Many potential best practices exist to reduce energy and refrigerant use, which could lead 

to reductions in GHG emissions. If potential best practices are aggressively implemented, it is 

possible for there to be a net decrease in total GHG emissions and energy use in freight 

transportation. Potential additional reductions might be possible if certain intermodal shifts are 

encouraged where possible. 

Limited quantitative data is available upon which to base assessments of the costs of 

potential best practices. For thirteen potential best practices for which adequate data are 

available, the normalized cost savings per unit of GHG emissions reduction was highly variable. 

Ten of these potential best practices produce net cost savings because of significant energy cost 

savings. Three of them have net cost increases because they involve substitution of alternative 

fuel. Switching from petroleum to biodiesel can reduce GHG emissions but increase total costs, 

based on recent fuel prices. 

Governments and individual owners or operators are encouraged to carefully compare 

their options. From a national policy perspective, some potential best practices, such as direct 

fired heaters and B20 biodiesel for the truck mode, offer greater potential for large magnitudes in 

reduction of total GHG emissions, but may not be as cost-effective as other practices. 

Additional research and development might result in reduced costs. From an individual owner 

or operator perspective, consideration of cost savings and cost effectiveness are more important. 

Some potential best practices may be a “no regrets” proposition and the owner or operator can 

realize a net cost savings. 

This guidebook makes no recommendations about the use of specific strategies as best 

practices because typically information for best practices is incomplete and does not enable 

situation-specific assessment and comparison. While it is clear that many potential best 
ES-13

practices will not be considered by potential adopters until adequate cost data is available upon 

which to estimate costs reliably, at this time insufficient data are available to characterize costs 

reliably for most of the best practices identified here. 

ES.6 Recommendations 

Information given here can be updated as new information becomes available. 

In this work, costs could be assessed for only 13 best practices. Since potential adopters 

of best practices need cost data for all of the possible best practices, there is a critical need for 

more cost information. Ongoing work is recommended to obtain or develop cost estimates for 

best practices for which costs are not reported here, as well as to update cost estimates reported 

here as new data become available. 

The impact of variations of key assumptions, such as market penetration rates, fuel prices, 

capital costs, and operation and maintenance costs, can be assessed via sensitivity analysis. 

Developing tools to support decision making regarding best practices are also 

recommended. Effective best practices are developed based on the conditions faced by a 

specific decision-maker, such as local fuel costs. It is critical to develop a decision support 

framework that will allow such parties to compare multiple best practices on the basis of 

representative and relevant important assumptions. 

A decision tree is helpful in situations of complex multistage decision problems for 

choosing best practices and can be applied to assist individuals in choosing from among many 

best practices. A decision tree involves a hierarchical cascade of questions to guide 

decision-maker toward promising best practices appropriate to their situations. The decision 

tree could be implemented in an interactive web-based format and may be publicly accessible. 
1

1.0 PURPOSE AND BACKGROUND 

Freight transportation is comprised of five major modes: truck, rail, air, water, and 

pipeline. Greenhouse gas (GHG) emissions from freight transportation account for 

approximately 9% of total greenhouse gas emissions in the United States.1,2,3 The contributions 

of these modes to total freight transportation GHG emissions are 60, 6, 5, 13, and 16 percent, 

respectively. Energy use for all freight modes, based on a long-term energy trend scenario, is 

estimated to increase approximately 75% from 2003 to 2030.4 Given this expected increase in 

the next quarter of this century, and since GHG emissions are largely based on energy use, GHG 

emissions from freight transportation are also expected to increase significantly in the future. 

There are a growing number of technological and operational strategies that could reduce 

GHG emissions from the freight sector. However, knowledge of these technological and 

operational strategies is not widespread. The objectives of this project are to review and 

investigate existing technological and operational emission reduction strategies, and to develop a 

guidebook summarizing potential best practices within the freight transportation sector. The 

objectives of this guidebook are to: (1) review existing technological and operational strategies 

to reduce greenhouse gas emissions, directly or indirectly, within the freight transportation sector; 

(2) develop a list of innovative technological and operational strategies (ongoing or completed) 

that can be considered as potential best practices; and (3) summarize and compare the various 

potential best practices. 

1.1 Purpose of This Guidebook 

A growing number of technological and operational strategies could reduce GHG emissions 

from the freight transportation sector.6-10 For example, as shown later, 14 identified energy 

efficiency strategies for the truck mode have the potential to reduce 3 billion gallons of fuel use 

and 33 million tons CO2 eq. annually in 2010,11 which is about 7% of the 2010 greenhouse gas 

emissions from the truck mode in the United States. These technological and operational 

strategies could offer freight transport owners and operators added benefits, such as: (1) lower 

fuel costs (if the program helps reduce fuel usage); (2) lower refrigerant costs (if the program 

helps reduce HFC usage); and (3) lower emissions of GHG and of air pollutants. Reductions in 

fuel or refrigerant usage would provide direct cost benefits to owners and operators, thereby 

creating at least partial incentives to adopt such technologies and programs. 

However, knowledge of existing technological and operational strategies, and their 

effectiveness at reducing greenhouse gas emissions, is not widespread throughout the freight 

transport community. An investigation of these strategies is needed to provide a consistent 
2

basis for identification and comparison of methods that are available to the freight sector to 

reduce GHG emissions. In addition, some technological and operational strategies, such as fuel 

and refrigerant saving strategies, that could have significant greenhouse gas reduction benefits, 

may not have originally been developed with respect to an objective of GHG emissions reduction. 

Efforts to reduce fuel or refrigerant use typically provide an added benefit of reducing GHG 

emissions. 

Thus, identifying and fostering the application of technological and operational strategies 

that can reduce GHG emissions, and fostering similar efforts, can provide multiple benefits of 

enabling choices that lead to reductions in greenhouse gas emissions. Such choices may often 

also reduce fuel use, other air pollutant emissions, and costs. This project supports 

knowledge-sharing through a guidebook on current best technological and operational strategies 

within the freight transportation sector. Best practices are typically undertaken by responsible 

parties at the local, state, and Federal government levels, or at the levels of individual or fleet 

owners and operators. This best practice guidebook is intended to provide information useful to 

responsible parties in the freight transportation sector in identifying, evaluating, and adopting 

similar technological and operational strategies. 

1.2 Background 

The freight transportation sector contributes significantly to greenhouse gas (GHG) 

emissions in the United States. The most important greenhouse gas is carbon dioxide (CO2), 

which is produced primarily from combustion of fossil fuels.1,5 Other important greenhouse 

gases include methane (CH4), nitrous oxide (N2O), and hydrofluorocarbons (HFCs).1,12 

HFC-134a is the most common HFC. Greenhouse gases are often compared based on their 

global warming potentials (GWPs). Global warming potentials are an indicator of the globally 

averaged relative radioactive forcing impacts of a particular GHG. CO2 is assumed as a datum 

with a GWP = 1. The GWPs of CH4, N2O, and HFC-134a are 21, 310, and 1,300, 

respectively.1,13 These GWPs are used to convert the mass emissions of CH4, N2O, and HFCs 

to an equivalent mass of CO2 with the same overall global warming impact.1

In 2003, total greenhouse gas emissions in the United States were estimated as 7,789×106

tons CO2 eq., including 94×106 tons CO2 eq. emissions from international aviation and marine 

transportation activities. The freight transportation sector in the United States emitted more 

than 719.8×106 tons CO2 eq. Thus, the freight transportation section is responsible for 

approximately 9.1 percent of the estimated total GHG emissions in the United States.1-3 The 

truck mode emits approximately 60% of GHGs in freight transportation, which is approximately 

5.4% of U.S. GHG emissions. The freight transport activities and GHG emissions in the freight 
3

transportation sector are summarized in Table 1-1.1-3 

Table 1- 1. Greenhouse Gas Emissions from the Freight Transportation Sector in 2003 

GHG Emissions (106 Tons CO2 eq.)1-3 Mode of 

Freight 

Transportation 

 Freight Transport 

Activity 

(Billion Ton-miles) 

CO2 CH4 N2O HFCs Total 

Trucks 1256 419.5 0.1 1.9 10.4 431.9 

Rail 1550 42.9 0.1 0.3 - 43.3 

Air 34 35.8 + 0.3 - 36.1 

Water 1588 95.0 0.1 0.2 - 95.3 

Pipeline 278 38.3 74.9 - - 113.2 

Total 4706 631.5 75.2 2.7 (10.4)a 719.8 

a: Data here only include the amount of HFC emissions for the truck mode.1 No detailed data are 

currently available for the amount of HFC emissions for the other four modes. Thus, the number 

shown here is a lower bound on freight transportation HFC emissions. 

These emissions are typically associated with combustion processes or leaks, the latter of 

which are also known as fugitive emissions. For example, CO2 is emitted primarily as a result 

of combustion of carbonaceous fuels (e.g., diesel fuel, jet fuel, residual fuel oil and natural gas). 

Methane can be emitted as a result of incomplete combustion of fuels and because of leaks in 

natural gas pipelines. N2O is emitted partly as a product of combustion and partly as a 

byproduct produced in some catalytic emission control systems. HFCs are typically emitted 

because of leakages in refrigeration and air conditioning systems. Of these four GHGs, the 

most reliable data are for CO2. HFCs emissions for truck mode have been estimated, but there 

are not readily available HFC emissions data for other freight modes.1

The data in Table 1-1 indicate that the majority of freight-related CO2 and N2O emissions 

are associated with trucks, whereas the majority of CH4 emissions are attributed to natural gas 

pipelines. Thus, GHG reduction strategies may be prioritized within these areas. Those 

modes that involve the use of refrigeration or air conditioning systems would be a priority for 

technological and operational strategies that could reduce HFC emissions. However, when 

considering the total global warming impact, CO2 emerges as the highest priority among the four 

GHGs considered here. Thus, CO2 emissions from trucks are a major focus area. 

A scenario of total freight-related GHG emissions over time, which is shown in Table 1-2, is 

developed based on estimated GHG emissions in 2003 and an energy trend scenario for all 

modes. The latter comes from a long-term energy trend scenario, “2005 Technology Case,” in 

the Energy Information Administration’s Annual Energy Outlook 2006, in which freight 
4

transportation energy use is estimated to increase approximately 52% from 2003 to 2025.4 

Since energy use for freight transportation will increase significantly in the next quarter of this 

century, and GHG emissions are largely based on energy use, GHG emissions from freight 

transportation are also estimated to increase significantly in the future. According to the 

scenario, greenhouse gas emissions for freight transportation are estimated to increase 

approximately 52% from 2003 to 2025. 

Table 1- 2. A Scenario of GHG Emissions from Freight Transportation from 2003 to 

2025 

Annual GHG Emissions (106 Mode of Freight Tons CO2 eq.)

Transportation 2003 2010 2015 2020 2025 

Growth 

2025 vs. 2003

Truck 432 520 588 649 721 67%

Rail 43 50 53 58 65 49%

Air 36 44 52 57 59 65%

Water 95 108 111 118 122 28%

Pipeline 113 107 121 131 130 14%

Total 720 828 925 1012 1096 52% 

Governments and the freight industry recognize the need for technological and operational 

strategies as to meet future challenges.2 There are a growing number strategies, either existing 

or developing, that could reduce GHG emissions from the freight sector. There is a need to 

review and characterize these strategies in order to support decision making regarding their 

potential adoption. 

1.3 Using This Guidebook 

This guidebook presents a survey of potential best practices for reducing energy use and 

GHG emissions in freight transportation. The survey includes characterization of each potential 

best practice in order to serve the information needs of responsible parties and decision makers. 

The organization and contents of this guidebook are summarized in Figure 1-1. Brief 

descriptive information regarding each potential best practice, which are sorted by subgroup, are 

described in Chapters 4 to 8 for the truck, rail, air, water, and pipeline modes, respectively. The 

potential reductions in GHG emissions and energy or refrigerant use for all modes are 

summarized in Chapter 9. Intermodal comparisons and intermodal shifts are discussed in 
5

Definitions and 

Concepts

Chapter 2

Methodology

Chapter 3

Fuel Properties

Appendix F

Background and Methodology

Assessments of Individual and Subgroups of 

Best Practices by Mode

Mode Summary Material Supporting Details

Truck Chapter 4 Appendix A

Rail Chapter 5 Appendix B

Air Chapter 6 Appendix C

Water Chapter 7 Appendix D

Pipeline Chapter 8 Appendix E

Summaries of and 

Comparisons 

Between Modes

Chapter 9

Conclusions and 

Recommendations

Chapter 10

Figure 1- 1. Overview of the Organization and Content of This Guidebook.

Chapter 9. For the potential best practices for which quantitative cost data are not available, 

they are assessed qualitatively. Assessment results for these are given in simplified summary 

tables in Appendices A through E for the truck, rail, air, water, and pipeline modes, respectively. 

For the best practices for which quantitative cost data are available, they are assessed 

quantitatively. Assessment results are given in standardized reporting tables. Details of the 

analyses of these practices are given in Appendices A through E for the truck, rail, air, water, and 

pipeline modes, respectively. The properties, CO2 emissions coefficients and average unit costs 

of fuels discussed are given in Appendix F. 

This guidebook is intended as a starting point of choosing and implementing strategies for 

the freight transportation sector in order to reduce GHG emissions. This guidebook is aimed at 

providing useful information to responsible and target parties regarding opportunities for 
6

reducing energy use, refrigerant use, and GHG emissions, as well as regarding the possible 

magnitude of such reductions. This guidebook contains brief information for many potential 

best practices in order to provide a comprehensive introduction to possible choices. This 

guidebook makes no recommendations regarding the use of specific strategies as best practices. 

Typically, information for best practices is incomplete and does not enable situation-specific 

assessment and comparison. 
7

2.0 DEFINITION OF KEY CONCEPTS 

This Chapter defines key terms concepts pertaining to “best practices,” transportation 

modes, organizations responsible for adopting best practices, greenhouse gases, types of 

strategies of best practices, and the developmental status of these strategies. 

2.1 “Best Practices” for Greenhouse Gas Reductions in Freight Transportation 

Best practices for greenhouse gas reductions in freight transportation are defined here as 

strategies within the freight transportation sector, whether they are technological or operational 

(see Section 2.4 for definitions), that are, or can be, implemented by responsible parties and that 

have been demonstrated to reduce, or have the potential to achieve reductions in, GHG 

emissions.14 Since the best practices identified are often of potential future applicability, they 

are referred to as potential best practices. 

Within the broad category of all best practices, there are distinguishing criteria that can be 

used to compare and evaluate specific practices. A framework for categorization and 

characterization of each best practice is described in Section 3.1. 

Best practices typically achieve GHG emissions reductions by reducing the use of energy, 

refrigerants, or both. Thus, this guidebook explicitly considers the capability of potential best 

practices to reduce GHG emissions, energy use, and refrigerant use. 

2.2 Modes of Freight Transportation 

Freight transportation, defined as the transportation of commodities, is comprised of five 

major modes: truck, rail, air, water, and pipeline.15

Highway transportation of freight is usually referred to as the “truck” mode.16 The 

standard measure of the activity of the truck mode is vehicle miles traveled (VMT). FHWA 

breaks down VMT figures by vehicle types. FHWA defines two types of trucks: (1) 

single-unit, 2-axle 6-tire,or 3+ axle trucks; and (2) combination trucks (single trailer and multiple 

trailer).2,17 Trucks can also be classified based on other vehicle characteristics, such as cab type, 

body type, vehicle size, and gross vehicle weight, which are defined by U.S. Bureau of 

Census.18-19 Classifications by cab type include: conventional cab (with sleeper, without 

sleeper, and others); cab over engine (with sleeper, without sleeper, and others); and cab forward 

of engine (cab beside engine and others).18 Classifications by body type include: (1) 

single-unit trucks, such as van, tank, and crane; and (2) truck-tractors, which have many types of 

trailers, such as automobile carrier, livestock, van, tank, and mobile home toter.18 
8

Classifications by vehicle size include: light, medium, light-heavy, and heavy-heavy.18 

Classifications by gross vehicle weight (GVW) are summarized in Table 2-1.18-19 The 

relationship among vehicle size, gross vehicle weight, number of axles, and number of tires are 

summarized in Table 2-1.18,20-21 Following the definitions of FHWA and U.S. Bureau of 

Census, the truck mode excludes trucks which gross vehicle weights are smaller than 10,000 

pounds (Class 1 and Class 2 trucks). 

Railroad freight transportation is referred to the “rail” mode. This mode includes freight 

transport on Classes I, II, and III railroads, as well as switching and terminal carriers.2 Class I 

railroads, which had operating revenues of at least $277.7 million in 2003, concentrate on 

long-haul, high-density intercity traffic lanes, and account for 93 percent of U.S. freight railroad 

revenue. Class II railroads are line-haul railroads with at least 350 route-miles, with revenues 

between $40 million and the Class I threshold, or both. Class II railroads are also called 

regional railroads because they typically serve a region located in two to four states. Class II 

railroads account for 3 percent of U.S. freight railroad revenue. Class III railroads operate less 

than 350 route-miles and earn less than $40 million per year. Class III railroads are also called 

local line-haul carriers because they typically serve a single state. Class III railroads account 

for 2 percent of U.S. freight railroad revenue. Switching and terminal carriers account for 2 

percent of U.S. freight railroad revenue.22 Class I railroads consume more than 94 percent of 

railroad fuel.2 Thus, a priority for greenhouse gas reduction within the rail mode is the Class I 

railroads. 

Air freight is transported in dedicated cargo aircraft and in cargo space of passenger aircraft. 

The latter is referred to as belly cargo. Both types of aircraft carry a significant amount of air 

cargo. In order to estimate aircraft emissions attributable to freight alone, it is customary to 

apportion passenger aircraft into passenger and freight components based on passenger and cargo 

weight.2

 

Water (or waterborne) freight transportation includes domestic commerce and international 

trade,16 and includes ships, barges, shallow draft vessels and deep draft vessels.23 Foreign trade 

accounts for 58 percent of waterborne tonnage, with import tonnage nearly 2.7 times more than 

export tonnage. Domestic waterborne tonnage is primarily inland movements (rivers and 

canals), with smaller amounts moving along the coasts, in the Great Lakes, and within ports.2 

In 2003, domestic water trade consumed 797 Tera BTU of energy, including 302 Tera BTU of 

distillate fuel oil and 495 Tera BTU of residual fuel oil.1, 3 Foreign water trade, at consumed 

322 Tera BTU of energy, including 83 Tera BTU of distillate fuel oil and 239 Tera BTU of 

residual fuel oil.1

 

The pipeline mode includes the movement of natural gas and oil. However, this guidebook 

refers only to the movement of natural gas via the pipeline mode because of insufficient 
9

Table 2- 1. Truck Classifications by Weight, Number of Axles, and Number of Tires19,21

Vehicle Size Class Gross Vehicle Weight (lbs) Number of Axles Number of Tires 

Light 1 <6,000 2 4 

2 6,000-10,000 2 4 

3 10,000-14,000 2 6 

4 14,000-16,000 2 6 

Medium 

5 16,000-19,500 2 6 

Light-Heavy 6 19,500-26,000 3 6 

Heavy 7 26,000-33,000 3 10 

8 >33,000 3 

3 + 

10 

10 + 

information for the movement of oil.3 The well-to-use of the pipeline system includes several 

stages: production, processing, transmission and storage, and distribution.1 In this guidebook, 

the transmission and distribution stages of the pipeline mode are considered. The pipeline 

mode emits carbon dioxide from burning methane as the fuel for powering the pipeline systems, 

and it also directly emits methane to the atmosphere, which includes fugitive emissions and 

vented emissions. Most of the methane emissions in the freight transportation are from the 

pipeline mode. 

2.3 Subgroup 

A subgroup within a mode is a collection of potential best practices in a mode that have 

either common goals or attributes. Subgroups are defined based on the factors that the practices 

can improve (e.g., in the case of the truck mode, idling, aerodynamics, rolling resistance, vehicle 

weight), or the technologies that vehicles or devices may apply (e.g., hybrid diesel-electric 

propulsion system, alternative fuels), to reduce GHG emissions. 

2.4 Responsible Parties 

A responsible party is a person or organization who has the authority to develop, promote, 

or select a best practice. Responsible parties can be classified as individuals (vehicle owners or 

operators), companies (fleet owners or manufacturers), and governments (local, state, and central 

governments in the United States and in other countries). When the strategies are in conceptual 

or developmental stages, academic institutions and non-governmental organizations may be also 

involved as responsible parties. For example, many universities are involved in projects to 
10

study strategies that have the potential to reduce energy use and GHG emissions, such as 

anti-idling, hybrid vehicles, and alternative fuels. 

2.5 Target Parties 

A target party is a person or organization who may implement a best practice. Target 

parties are classified as individuals (vehicle owners or operators) and companies (fleet owners). 

2.6 Greenhouse Gas Emissions 

The operation of freight transportation is responsible for the emissions of four major 

greenhouse gases: carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and 

hydrofluorocarbons (HFCs), which have different GWPs, as discussed in Section 1.2. These 

four gases are considered. However, priority is given to CO2 since it is emitted in the largest 

quantity with respect to global warming potential. 

2.7 Strategy Types for Reducing Greenhouse Gas Emissions 

There are two general types of best practice strategies. A strategy can be either 

technolgical or operational.2 These two categories are defined here. 

2.7.1 Technological Strategies 

Technological strategies modify, replace, or enhance a piece or system of equipment, its fuel, 

or its refrigerant to reduce GHG emissions. As examples, technological strategies may involve 

replacing an existing engine with a new one, converting diesel-powered equipment to electrical 

power, using alternative fuels or refrigerants, replacing older freight equipment, having an engine 

repaired or rebuilt, or improving fuel economy.2

2.7.2 Operational Strategies 

Operational strategies change the way that vehicles and freight transportation systems 

operate, resulting in fewer GHG emissions. These strategies may reduce fuel or refrigerant uses 

and result in lower operating costs for the equipment owner. These strategies may involve 

improving freight operating efficiency (e.g., minimizing “empty mileage,” which refers to the 

movement of empty commercial vehicles) through improved freight logistics results in greater 

fuel productivity and more ton-miles of freight moved per unit of fuel consumption),2

 reducing 

congestion, reducing unnecessary idling, reducing empty mileage, increasing load factors, 

eliminating circuitous routing, and others. Assessing the effect of these operational strategies 

on emissions, however, can be difficult because there may be little relevant quantitative 
11

information. In some cases, extensive modeling of the performance of an integrated freight 

transportation system could be required, which is beyond the scope of this work.2

2.8 Practice Goals 

Practice goals include the percentage reductions in GHG emissions, energy use or 

refrigerant use. The goals may be specific to particular transportation technologies or devices. 

A particular practice may only be applicable to a fraction of all devices within a mode. For 

example, anti-idling strategies for the truck mode are only applicable for long-haul trucks with 

sleeper cabs that typically have extended idling for mandatory driver rest periods. This 

particular type of trucks contributes only a fraction of all freight transport activity within the 

truck mode. 

Percentage reductions in GHG emissions, energy use or refrigerant use are estimated based 

on the difference in 2025 modal GHG emissions, energy use, or refrigerant use with and without 

the selected potential best practice, divided by the total modal emissions if no potential best 

practice is implemented. 

2.9 Developmental Status 

Developmental status includes new concepts, pilot tests, and commercially available 

systems. New concepts include basic research activities, applied research activities, and 

experiments at the laboratory level. Pilot tests include prototype vehicles and demonstration 

projects. Commercially available systems can be purchased or implemented now. 
12

3.0 METHODOLOGY 

The methodology for characterizing and evaluating potential best practices includes: 

reviewing literature to identify existing or developing potential best practices and to develop a 

preliminary list of potential best practices; categorizing and characterizing potential best 

practices; assessing their reductions in GHG emissions, energy use or refrigerant use; assessing 

annualized practice costs, and energy or refrigerant costs reductions; assessing cost savings; and 

summarizing and reporting assessment results. 

The potential best practices identified here are often of potential future applicability, since 

many of them have not been implemented widely and some are preliminary concepts. Thus, in 

many cases, there is not adequate data available with which to quantify cost. Therefore, the 

methodology includes both qualitative and quantitative approaches. 

3.1 Literature Review 

A list of potential best practices was identified, mostly based on literature review. Most 

data and information regarding potential best practices was taken from published technical and 

policy reports, books, and engineering journal papers, although some information was collected 

from websites. Some information was collected from personal communications with experts 

via email and telephone. 

3.2 Reductions in GHG Emissions, and Energy or Refrigerant Use, for Individual Best 

Practices 

Quantitative assessments were made for reductions in GHG emissions, energy use or 

refrigerant use in all cases, and for practice cost, energy or refrigerant cost reduction, and cost 

savings, where sufficient data were available. Where quantitative cost data were not available, 

the resource implications of the practices are discussed qualitatively in a structured approach. 

The percentage contributions of CO2, CH4, N2O and HFCs emissions to the total GHG 

emissions in terms of CO2 equivalent for all five modes are listed in Table 3-1, based on the 

results of Table 1-1. The total GHG emissions for the truck mode are mainly contributed by 

CO2 emissions from fuel use. A small fraction of the total freight truck GHG emissions is 

contributed by HFCs emissions from refrigerant use. The contributions of CH4 emissions and 

N2O emissions to the total freight truck GHG emission are insignificant. Thus, the 

opportunities to significantly reduce freight truck GHG emissions are based on reductions in CO2

and HFC emissions. 
13

Table 3-1 . Contribution of Selected Greenhouse Gases to Total Modal Greenhouse Gas 

Emissions 

Greenhouse Percentage Contribution to Each Freight Transport Mode (%) 

Gases Truck Rail Air Water Pipeline 

CO2 97.1 99.1 99.2 99.7 33.8 

CH4 0.0 0.2 0.0 0.1 66.2 

N2O 0.4 0.7 0.8 0.2 N/Aa

HFC 2.4 N/Aa N/Aa N/Aa N/Aa

a

 No data are currently available. 

The total GHG emissions for the rail, air and water modes are mainly contributed by CO2

emissions from fuel use, which are also illustrated in Table 3-1. The contributions of CH4

emissions, N2O emissions and HFC emissions to the total GHG emission are either insignificant 

or having no available data currently. Thus, the opportunities to significantly reduce GHG 

emissions for these three modes are based on reductions in CO2 emissions. 

CH4 is larger contributor to total GHG emissions for the pipeline mode than CO2, as shown 

in Table 3-1. For potential best practices for the pipeline mode, the reductions in GHG 

emissions are based on reductions in CH4 emissions. 

Reductions in GHG emissions and energy use for all potential best practices, except those 

based on alternative fuel strategies, are estimated based on direct emissions inventories. 

Reductions for alternative fuel strategies are estimated based on life cycle inventories. 

Reductions in refrigerant use are estimated based on estimates of the refrigerant leakage rate 

reduction or the GWP difference between low global-warming-potential refrigerants and original 

refrigerants. While the scope of this work includes the estimate of GHG emissions, energy use, 

and refrigerant use, for simplicity and brevity we simply use the term “emissions” in this section. 

Per-device reductions for each potential best practice, except for alternative fuel strategies, 

are estimated based on the differences in per-device emissions with or without use this potential 

best practice divided by per-device emissions if no potential best practice is implemented. 

Reductions for alternative fuel strategies are estimated based on life cycle inventories. 

The potential reductions in modal GHG emissions and energy or refrigerant use for an 

identified potential best practice are estimated based on the difference in 2025 modal emissions 

with and without the selected potential best practice divided by the total modal emissions if no 

potential best practice is implemented. Since a particular practice may only be applicable to a 

fraction of all devices within a mode and these applicable devices contribute only a fraction of all 
14

freight transport activity within this mode, the reductions in modal emissions for this practice is 

also a fraction of its per-device reductions. For example, trucks of all types are estimated to 

carry 2.1 trillion ton-miles per year. Long-haul trucks with sleeper cabs, which are a portion 

of all trucks, carry 450 billion ton-miles per year. Since strategies aimed at avoiding extended 

idling during rest periods can be only adopted by these long-haul trucks, these strategies are only 

applicable to, at most, 21 percent of total truck freight movement. The transport activity to 

which anti-idling strategies are applicable is, therefore, a portion of the transport activity of the 

freight truck industry. An assumption is made that each potential best practice can reach a 

potential best estimate of maximum market penetration by 2025. Technical, practical, and cost 

barriers are not quantified here. Actual market penetration may be lower than estimated. 

However, the estimates provide a useful upper bound as to what might be achieved if adoption of 

such practices is given practically. Details of these assumptions are given in Appendices A 

through E. 

3.3 Quantitative Assessments of Best Practices 

For all potential best practices, quantitative estimates are given for reductions in GHG 

emissions, energy use, and refrigerant leakage or GWPs. Furthermore, where sufficient data are 

available, quantitative assessments for cost effectiveness are performed for: practice cost; 

energy or refrigerant cost reduction; net savings per unit of reductions in GHG emissions and 

energy or refrigerant use; and simple payback period. The characteristics and the assessment 

results of the potential best practices are summarized in standardized reporting tables. 

3.3.1. Quantifying Cost Implications 

The methods for estimating the reductions in GHG emissions, energy use or refrigerant use 

are described in Section 3.2. 

Total net savings of implementing a potential best practice is the difference between annual 

energy or refrigerant costs savings and the annualized costs, the latter of which includes levelized 

capital costs and annual operation and maintenance costs. Net savings are normalized per unit 

of reduction in GHG emissions or energy or refrigerant use. A positive value of net savings 

means that the potential best practice will pay for itself over some period of time, whereas a 

negative value means that the annualized costs exceed savings associated with reductions in 

energy use, refrigerant use, or both. 

Simple payback periods are estimated based on the number of years required to recoup any 

additional capital or initial costs that lead to reductions in energy or refrigerant use (or any other 

cost-saving benefits). Such estimates are based on a discount rate of zero. These estimates are 
15

made where adequate data are available. 

3.3.2 Summarizing and Reporting the Results 

For each potential best practice for which sufficient information is available for a 

quantitative assessment, a standardized reporting table, which includes three parts, is used to 

report its quantitative characteristics and assessment results. The standardized reporting table is 

given in the format of Table 3-2. 

The first part of the table summarizes the characteristics of the potential best practice, 

including: practice name; applicable mode type; subgroup; responsible parties and target 

parties; targeted GHGs; strategy type; practice goals; developmental status; and practice 

summary. Each of these is briefly explained. 

(1) Practice name: The name of the technology or operation. 

(2) Mode type: Mode types are sorted by code: 1 = truck; 2 = rail; 3 = air; 4 = water; 

and 5 = pipeline. 

(3) Subgroup: Each mode type can be divided into two or more subgroups based on 

the factors that the practices can improve or the technologies that devices may 

apply. For example, the truck mode is divided into anti-idling, air conditioning 

system improvement, aerodynamics improvement, tire rolling resistance 

improvement, and other subgroups. 

(4) Responsible parties: These are categorized by individuals, companies, research 

institutions, local governments, state governments, and Federal government. A 

standardized list of responsible parties is given in Table 3-3. 

(5) Target parties: These are categorized by individuals and companies. As noted 

in Section 2.4, target parties may differ from responsible parties. A standardized 

list of target parties is also given in Table 3-3. 

(6) Target GHGs: CO2, CH4, N2O, HFCs, or combinations of these. 

(7) Strategy type: Technology, operational, or both. 

(8) Practice goals: Practice goals include the types of devices that can adopt this 

practice and percentage reductions in GHG emissions, energy use or refrigerant 

use. Devices that can adopt this practice may be only a portion of all devices in 

the industry. 

(9) Developmental status: Developmental stages are sorted by code: N = new 

concepts; P = pilot tests; and C = commercially available systems. 

(10) Practice summary: A brief description of the implementation of the practice. 
16

Table 3- 2. The Format of Standardized Reporting Table

Characteristics of the Practice Description 

Practice Name 

Mode Type 

Subgroup 

Responsible Parties 

Target Parties 

Target GHGs 

Strategy Type 

Practice Goals 

Developmental Status 

Practice Summary 

Emissions, Energy Use, and Refrigerant Use Unit Value 

Annual Transport Activity for the Mode (ATAM) 109 ton-miles/year 

Annual Transport Activity to Which a Practice Is 

Applicable (ATAP)a 109

 ton-miles/year 

Annual GHG Emissions Reductions(AGR) 106 ton CO2 eq./year 

Annual Energy Use Reduction (AER) 1012 BTU /year 

Annual Refrigerant Use Reduction (ARR) lbs/year 

Unit GHG Emissions Reductions (UGER)b 10-3 lb CO2 eq./ton-mile 

Unit Energy Use Reduction (UER)c BTU /ton-mile 

Unit Refrigerant Use Reduction (URR)d lbs/ton-mile 

Practice Costs 

Capital Cost (C) 106 USD ($) 

Discount Rate (r) % 10% 

Technical Lifetime of Technology (L) years 

Fixed Charge Factor (a)e year-1 

Annual O & M Cost (AOM) $106 /year 

Annualized Cost (AC)f $106 /year 

Annual Energy Cost Saving (AECS) $106 /year 

Annual Refrigerant Cost Saving (ARCS) $106 /year 

Net Savings (NS)g $106 /year 

Net Savings per Unit of GHG Emissions Reductions 

(NSGR)h $/ton CO2 eq. 

Net Savings per Unit of Energy Use Reduction 

(NSER)i $/106

 BTU 

Net Savings per Unit of Refrigerant Use Reduction 

(NSRR)j $/lb 

Simple Payback Period (SPP)k years 

a: Each practice may only be applicable to a fraction of all devices within a mode. Thus, annual 

transport activity to which a practice is applicable (ATAP) is the transport activity performed 

by the fraction of all devices within a mode to which a practice can be applied, and ATAP is 

a fraction of annual transport activity for the mode (ATAM). 

b: ( ) ATAP

AGR Unit GHG Emissions Re ductions UGER =

(Continued on next page) 
17

(Table 3-2. continued) 

c: ( ) ATAP

AER Unit Energy Use Re duction UER =

d: ( ) ATAP

ARR Unit Refrigerant Use Reduction URR =

e: Fixed charge factor depends on the discount rate (r) and the technical lifetime (L). 

( )

( ) 































+

=

∑=

L

i 1

i 1 r

1

1 Fixed Charge Factor a

f: Annualized Cost ( )( ) AC = C × a + AOM

g: Net Savings ( ) NS = (AECS or ARCS )− (C× a )− AOM

h: ( ) AGR

NS Net Savings per Unit of GHG Emissions Reductions NSGR =

i: ( ) AER

NS Net Savings per Unit of Energy Use Re duction NSER =

j: ( ) ARR

NS Net Savings per Unit of Refrigeran t Use Re duction NSRR =

k: ( ) ( ) AECS or ARCS AOM

C Simple Payback Period SPP − =
18

The second part of the standardized reporting table includes: the magnitude of transport 

activity for the entire mode; the magnitude of transport activity to which the practice is 

applicable; total GHG emissions reductions per year; total energy use reduction per year; total 

refrigerant use reduction per year; and reductions per unit of freight transport (e.g., GHG 

emissions reductions per unit of freight transport, which has the unit of lb CO2 eq. per ton-mile). 

The third part of the standardized reporting table focuses on cost. This part includes: 

annualized costs; energy or refrigerant costs savings; net savings per unit of reduction in GHG 

emissions and energy or refrigerant use; and simple payback period. 

3.4 Qualitative Assessments of Best Practices 

For each potential best practice for which there is a lack of adequate quantitative data and 

detailed information, qualitative assessments results are summarized in a simplified summary 

table, which is given in the format of Table 3-4. A simplified summary table includes: (a) 

technological information; (b) percentage reductions in GHG emissions, energy use or 

refrigerant use; (c) cost information; and (d) a description of benefits and drawbacks of the 

practice. 

Technological information includes: practice name; applicable mode type; subgroup; 

responsible parties; target parties; target GHGs of interest; strategy type; practice goals for GHG 

emissions reduction; developmental status; and a brief summary of the practice. The 

information for these items has been explained in Section 3.3.2. The second part of the table 

includes the potential reductions in modal GHG emissions, energy use or refrigerant use for 

individual potential best practices, which are quantitatively. 

Cost information is any available knowledge, such as capital cost assumptions, cost 

premiums or cost savings assumptions and retail price impacts reported in the literature. 

Benefits and drawbacks of the potential best practice are also discussed and summarized. 

However, typically such information is incomplete and does not enable estimation of net cost 

savings in the same manner as for those practices for which detailed quantitative information is 

available. 

3.5 Aggregated Reductions in GHG Emissions, Energy or Refrigerant Use for Multiple 

Best Practices 

Aggregate reductions in modal GHG emissions, energy use, or refrigerant use for an 

individual subgroup are estimated based on a simple linear combination of the reductions for 

multiple best practices within the subgroup, except as noted below. 
19

Table 3- 3. A Standardized List of Responsible Parties and Target Parties24

Mode Category Responsible Parties Target Parties 

Individuals 

1. 

2. 

3. 

4. 

Individual truck drivers 

Fleet truck drivers 

Truck loading operators 

Truck maintenance workers 

1. 

2. 

3. 

4. 

5. 

Individual truck drivers 

Fleet truck drivers 

Truck loading operators 

Truck maintenance workers 

Truck goods shippers 

Companies 

5. 

6. 

7. 

8. 

9. 

10. 

11 

. 

12. 

13. 

14. 

15. 

Truck operating companies 

Truck manufacturing companies 

Truck trailer manufacturing companies 

Electrical and electronic equipment 

manufacturing companies 

Transmission and power train parts 

manufacturing companies 

Metal stamping companies 

Air-conditioning manufacturing 

companies 

Truck maintenance companies 

Truck stop or rest area owners 

Fuel companies 

Lubricant companies 

6. 

7. 

8. 

Truck operating companies 

Truck maintenance 

companies 

Truck stop or rest area 

owners 

Research 

Institutions 

16. 

17. 

18. 

19. 

University 

Non-governmental organization 

National laboratory 

Private research institution 

Truck 

Governments 

20. 

21. 

22. 

Local governments 

State governments 

Federal government 

Individuals 

23. 

24. 

25. 

Locomotive drivers and crews 

Railroad operators 

Railroad maintenance workers 

8. 

9. 

10. 

Locomotive drivers and 

crews 

Railroad operators 

Railroad maintenance 

workers 

Companies 

26. 

27. 

28. 

29. 

30. 

Railroad companies 

Railroad rolling stock manufacturing 

companies 

Railroad goods shippers 

Fuel companies 

Lubricant companies 

11. 

12. 

13. 

Railroad companies 

Railroad maintenance 

companies 

Railroad goods shippers 

Research 

Institutions 

31. 

32. 

33. 

34. 

University 

Non-governmental organization 

National laboratory 

Private research institution 

Rail 

Governments 

35. 

36. 

37. 

Local governments 

State governments 

Federal government 

Air Individuals 38. 

39. 

40. 

Aircraft pilots and crews 

Airport operators 

Aircraft maintenance workers 

14. 

15. 

16. 

Aircraft pilots and crews 

Airport operators 

Aircraft maintenance 

workers 

Continued on Next Page. 
20

Table 3-3. Continued.

Mode Category Responsible Parties Target Parties 

Companies 

41. 

42. 

43. 

44. 

45. 

46. 

47. 

Aircraft companies 

Aircraft manufacturing companies 

Aircraft engine and engine parts 

manufacturing companies 

Aircraft parts and auxiliary equipment 

manufacturing companies 

Airport operation companies 

Fuel companies 

Lubricant companies 

17. 

18. 

19. 

Aircraft companies 

Airport operation companies 

Aircraft goods shippers 

Research 

Institutions 

48. 

49. 

50. 

51. 

University 

Non-governmental organization 

National laboratory 

Private research institution 

Air 

Governments 

52. 

53. 

54. 

Local governments 

State governments 

Federal government 

Individuals 

55. 

56. 

57. 

Ship captains and crews 

Port operators 

Ship maintenance workers 

20. 

21. 

22. 

Ship captains and crews 

Port operators 

Ship maintenance workers 

Companies 

58. 

59. 

60. 

61. 

62. 

Shipping companies 

Ship building and repairing companies 

Port operation companies 

Fuel companies 

Lubricant companies 

23. 

24. 

25. 

Shipping companies 

Port operation companies 

Ship goods shippers 

Research 

Institutions 

63. 

64. 

65. 

66. 

University 

Non-governmental organization 

National laboratory 

Private research institution 

Water 

Governments 

67. 

68. 

69. 

Local governments 

State governments 

Federal government 

Individuals 70. 

71. 

Pipeline system operators 

Pipeline system maintenance workers 

26. 

27. 

Pipeline system operators 

Pipeline system 

maintenance workers 

Companies 

72. 

73. 

Natural gas pipeline operation 

companies 

Natural gas pipeline system 

manufacturing companies 

28. 

29. 

Natural gas pipeline 

operation companies 

Natural gas shippers 

Research 

Institutions 

74. 

75. 

76. 

77. 

University 

Non-governmental organization 

National laboratory 

Private research institution 

Pipeline 

Governments 

78. 

79. 

80. 

Local governments 

State governments 

Federal government 
21

Table 3- 4. The Format of Simplified Summary Tables 

Attribute Description 

Practice Name 

Mode Type 

Subgroup 

Responsible Parties 

Target Parties 

Target GHGs 

Strategy Type 

Practice Goals 

Developmental Status 

Practice Summary 

Potential Reductions in 

Modal GHG Emissions 

Potential Reduction in 

Modal Energy Use 

Potential Reduction in 

Modal HFC Use 

Cost Information 

Benefits and Drawbacks 

Within a subgroup, it is possible that two or more best practices may be mutually exclusive 

in serving similar functions or requiring installation on the same location of a vehicle or system. 

In the case of mutual exclusion, the best practice with the highest estimated reduction is used in 

the estimate of total modal reductions for the subgroup. For example, three alternative 

refrigerants for air conditioning systems that could be used as best practices are mutually 

exclusive. Only one refrigerant can be used in an air conditioning system. CO2 is chosen here 

because it has the lowest GWP compared to the other candidate refrigerants and its potential 

reductions in modal GHG emissions are the highest. Thus, the estimates do not double count 

mutually exclusive best practices. 

In a subgroup, it is possible that several best practices are not mutually exclusive and could 

be implemented simultaneously. However, the total reduction may not be a simple linear 

combination of the reductions of each individual practice because the practices may have 

interactive effects. For example, the combined reduction in aerodynamic drags of several best 

practices would not be a linear sum of the drag reduction of each practice individually. Since 

there is a lack of data upon which to quantify the overall reduction associated with interactions 

among multiple best practices within a subgroup, each interactive effect are not quantified. The 

linear combination may tend to overestimate the maximum possible reductions for the subgroup. 

Total reductions in modal GHG emissions and energy or refrigerant use for all best 

practices are estimated based on summing the reductions of each subgroup. The contribution of 

a subgroup to total reductions in modal GHG emissions and energy or refrigerant use is 
22

estimated, and it is normalized by dividing the aggregate reductions for a subgroup by total 

modal reductions for all best practices for this mode. 

3.6 Intermodal Substitution 

In some situations, it may be possible to substitute one mode for another for a given 

shipment, either partially or fully. From the estimates of 2003 freight transport activities and 

GHG emissions for individual modes in Section 1.2, the unit GHG emissions of each of these 

modes are 0.69, 0.06, 2.15, 0.12, and 0.81 lb CO2 per ton-mile for truck, rail, air, water, and 

pipeline, respectively. If it were possible to substitute some or all of a trucking or air trip with 

transport by rail or water-borne vessel, there could be a reduction in GHG emissions. For 

example, instead of transporting goods by truck from the origin to the destination, it may be 

possible to transport the goods by truck from the origin to a rail terminal, continue the shipment 

by rail for most of the mileage of the trip, and offload the goods to a local truck for delivery at 

the destination. 

An upper-bound estimate of the reduction in GHG emissions from inter-modal substitution 

of rail for trucking can be developed by assuming that all of the truck transport ton-miles are 

replaced by the same amount of rail transport ton-miles. In reality, the substitution would not 

be complete, since some truck miles would likely be required at the origin, destination, or both. 

The methodology for assessment of intermodal substitutions is described in Section 9.6.3. 
23

4.0. BEST PRACTICES FOR THE TRUCK MODE 

This chapter identifies and characterizes 33 potential best practices applicable to the truck 

mode. These best practices are divided into 11 subgroups, including: 

• reduction in fuel use and emissions during extended idling, 

• air conditioning system improvement, 

• reduction in aerodynamic drag, 

• reduction in tire rolling resistance, 

• hybrid propulsion, 

• weight reduction, 

• improved transmission efficiency, 

• improved diesel engine efficiency, 

• reduction in accessory load, 

• modifications in driver operational practices, and 

• alternative fuels. 

Additional details regarding all of these best practices are in Appendix A, including the 

basis for estimated reductions in GHG emissions, energy use, and refrigerant use. For five of 

these practices, sufficient data were available to quantify costs. 

4.1 Anti-Idling 

Long distance truck drivers are required to take mandatory rest stops. These rest stops 

are intended to promote safety by reducing driver fatigue. Approximately 0.68 million 

long-haul trucks are equipped sleeper cabs.3

 Sleeper cabs contain a small living environment 

with sleeping accommodations. The advantage of a sleeper cab is that the driver can take rest 

stops at any location where the truck can be parked, rather than have to stay at a hotel. Such 

compartments require heating, ventilation or air conditioning (HVAC), often have small 

appliances such as refrigerators and microwave ovens, and have electrical outlets to support 

other auxiliary loads such as television or computers. Conventionally, the heating, cooling, and 

power requirements for the sleeper cab during driver rest time are supplied by the diesel-fueled 

base engine of the truck. These engines are run under extended idling conditions for continuous 

periods of many hours. According to the literature, a typical base engine may consume 0.85 

gallons of fuel per hour during idle.25 The actual amount of fuel consumption varies among 

different engines and depends on the HVAC and electrical loads. A number of so-called 

“anti-idling” techniques have been introduced. The objective of these techniques is to avoid 
24

use of the base engine during extended idle by substituting alternative sources of HVAC and 

electricity during rest stops. Some techniques involve installation and operation of on-board 

systems, while others require connecting the truck to a “shore-based” facility. 

4.1.1 Best Practice 1-1: Off-Board Truck Stop Electrification 

Off-board truck stop electrification is a commercially available system that can avoid the 

need for idling of the truck base engine while a truck is parked at a truck stop. This external 

system enables a truck driver to switch off the base engine by connecting the truck to a specially 

designed service module. This module provides heating, air conditioning and electricity to the 

truck cab, and it is installed temporarily through a window of the truck. This system is reported 

to consume less energy than the base engine and emits less CO2.

26-29 A commercially available 

example of this is the IdleAire system.30 The projected 2025 modal GHG emissions are 

721×106 tons of CO2 eq., and the potential reduction in modal GHG emissions are 2.4 ×106 tons 

of CO2 eq. Thus, the estimated potential reduction in modal GHG emissions are 0.3%. 

Trucks cannot use this alternative unless they are parked at a truck stop with this type of 

electrification system. 

4.1.2 Best Practice 1-2: Truck-Board Truck Stop Electrification 

In contrast to Best Practice 1-1, which involves an external service module, truck stop 

electrification can be as simple as connecting the truck to a shore-based power supply via an 

electrical cable. This type of system is effective in situations where the HVAC system of the 

sleeper cab is entirely electrically operated and, thus, is independent of the base engine. This 

system is connected to the electrical grid. Thus, the energy use and emissions for this best 

practice are associated with those of the power grid. Compared to use of the base engine, this 

type of electrification is reported to consume less energy and emits less CO2.

28-29,31 The 

estimated potential reduction in modal GHG emissions are 0.4%. Trucks cannot use this 

alternative unless they are parked at a truck stop with this type of electrification system. 

4.1.3 Best Practice 1-3: Auxiliary Power Units 

Auxiliary power units (APUs) are commercially available systems that can avoid the 

need for idling of a truck’s base engine. An APU is installed on a truck and consists of a small 

diesel engine that provides power for an HVAC system and electrical outlets that service the 

sleeper cab. APUs are advertised as consuming less fuel under typical load conditions than the 

base engine. There are some practical questions regarding whether APUs are sufficiently quiet 

for use while a driver is sleeping, especially if they cycle on and off to meet intermittent A/C 

compressor demand, regarding their ability to rapidly cool-down the cab on very hot days, and 
25

their actual fuel efficiency relative to base engines. Based on available information, APUs are 

estimated to consume less diesel fuel than the base engine and emit less CO2.

27,32 The 

estimated potential reduction in modal GHG emissions are 2.1%. One disadvantage of this 

practice is its high capital cost. The capital cost of this practice may be even higher if it 

requires tailpipe emissions control devices. There is uncertainty regarding the real world 

relationship between fuel use rates of APUs compared to those of truck base engine, which 

confounds the ability to accurately estimate the fuel saving potential of this practice. 

4.1.4 Best Practice 1-4: Direct-Fired Heaters 

Direct-fired heaters are commercially available systems for heating a sleeper cab by 

burning diesel fuel. Heat from combustion gases passes through a heat exchanger that warms 

the air inside the sleeper cab. In addition, these heater systems can be configured to provide 

heat for the base engine to maintain readiness for base engine restart in cold weather. Unlike 

the previous three best practices described above, this system is only applicable to heating in 

cold weather and does not provide cooling in hot weather. Furthermore, this system does not 

provide electrical power; instead, electrical power is drawn from the truck’s existing battery. 

Direct-fired heaters are reported to consume less diesel fuel than the base diesel engines and to 

emit less CO2.

27 The estimated potential reduction in modal GHG emissions are 1.1%. 

4.1.5 Best Practice 1-5: Direct-Fired Heaters with Thermal Storage Units 

Thermal storage systems consist of a phase change material that can be heated or cooled 

from the truck cab air conditioning unit or heating system while the base engine is operating. 

These systems are demonstrated. The thermal storage system can be used as a means of 

providing warm or cool air to the sleeper cab via a heat exchanger and a blower unit when the 

base engine is off. In order to supplement the heating capability, thermal storage systems can 

be coupled with direct-fired heaters to store more thermal energy that is available for warming 

interior cabin air even when the direct-fired heater is not operating. This system supplies 

heating and cooling, but no electrical power, to the sleeper compartment when the base engine is 

off. Furthermore, similar to Best Practice 1-4, this system does not provide electrical power; 

instead, electrical power is drawn from the truck’s existing battery. The combination of 

direct-fired heaters and thermal storage units is reported to consume less energy than the base 

diesel engines and to reduce CO2 emissions. The potential reduction in modal GHG emissions 

may be as large as 2.9%.27 The disadvantage of this practice is that it supplies no electricity, 

and requires power from the vehicle’s batteries. 
26

4.2 Air Conditioning System Improvement 

Mobile air conditioning systems cause "direct" and “indirect” GHG emissions. Direct 

GHG emissions are due to refrigerant leakage. Indirect GHG emissions are additional exhaust 

CO2 emissions that result from the engine load due to operation of the air conditioning system 

compressor. Refrigerant leakage rate reduction or use of low global-warming-potential (GWP) 

refrigerants can reduce direct emissions. Increasing the energy efficiency of air conditioning 

system can reduce indirect emissions. The estimates of potential reduction in modal GHG 

emissions for best practices within this subgroup are mainly based on a California governmental 

report.33 

4.2.1 Best Practice 1-6: Enhanced Air Conditioning System I - for Direct 

Emissions 

Enhanced air conditioning systems, which are undergoing testing, can reduce direct GHG 

emissions by reducing the leakage rate of the commonly used HFC-134a refrigerant. The 

refrigerant leakage rates of these systems may be decreased through the use of low permeable 

hoses, improved hose ends and connectors, and improved compressor shaft seals.12,33-35 The 

estimated potential reductions in modal GHG emissions are 0.9%.33 There is not as yet a 

standard method for testing and certifying the leakage rate of an enhanced system is in the 

developmental stage. 

4.2.2 Best Practice 1-7: Enhanced Air Conditioning System II - for Indirect 

Emissions 

Enhanced air conditioning systems for reducing indirect GHG emissions are 

commercially available. These systems can decrease base engine load requirements from 

mobile air conditioning systems by replacing fixed displacement compressors (FDCs) with 

externally controlled variable displacement compressors (VDC), using improved control systems, 

and using improved condensers and evaporators. By reducing the engine load requirements, 

exhaust CO2 emissions can be reduced.

33,36-37 The benefit of reducing engine load is only 

available in hot weather when the A/C system is used. The estimated potential reductions in 

modal GHG emissions are 0.2%. 33 

4.2.3 Best Practice 1-8: Alternative Refrigerants - CO2

The GWP of leaking refrigerant can be reduced by using an alternative low GWP 

refrigerant. The current widely used refrigerant, HFC-134a, has GWP = 1,300, whereas CO2

has GWP = 1. Therefore, CO2 is being investigated as an alternative refrigerant. This system 
27

is in the developmental stage. Engineers are working to improve the reliability and efficiency 

of systems that use CO2 refrigerant.12,33-34,36 The estimated potential reductions in modal GHG 

emissions are 2.5%. 33 Safety assessment and potential risk mitigation may be needed because 

of different safety characteristics of this alternative refrigerant compared to HFC-134a. 

4.2.4 Best Practice 1-9: Alternative Refrigerants - HFC-152a 

HFC-152a is another promising low GWP refrigerant. HFC-152a has a lower GWP 

(120) than that of HFC-134a. The transition from one HFC to another, such as from HFC-134a 

to HFC-152a, would be relatively easy (compared a transition to CO2) since these two 

refrigerants have similar properties and A/C system components would need less 

modification.26,27,42 The estimated potential reductions in modal GHG emissions are 2.4%.33 

The flammability of this alternative refrigerant, although moderate, motivates the need for 

additional safety assessment and potential risk mitigation. 

4.2.5 Best Practice 1-10: Alternative Refrigerants - HC 

Propane has been proposed as an alternative refrigerant for vehicle air conditioners. 

Propane has a lower GWP (20) than that of HFC-134a.38 This mobile hydrocarbon system has 

had more than 400,000 accumulated unit-years of operating experience in Australia. However, 

a propane-based refrigerant system uses more energy for operation and increases indirect GHG 

emissions, thus there is some trade-off.34 Furthermore, there is concern regarding its safety.36 

If such systems are accepted for use in the U.S., the estimated potential reductions in modal 

GHG emissions are 2.5%. 33 The flammability of this alternative refrigerant motivates the need 

for additional safety assessment and potential risk mitigation. Release of propane to the 

atmosphere may also increase tropospheric ozone formation. 

4.3 Aerodynamic Drag Reduction 

Typical heavy-duty trucks need to use a significant portion of fuel to overcome 

aerodynamic drag. Since higher speed causes larger aerodynamic drag, the effect of 

aerodynamic drag on fuel economy is higher at highway speeds compared to local road speeds. 

Thus, reduction of aerodynamic drag may significantly improve the fuel efficiency of trucks, 

especially during highway speed operations.39 Aerodynamic drag can be significantly reduced 

by installing add-on devices to improve the vehicle profile, pneumatic blowing systems, and boat 

tail plates, or by improving vehicle load profile. 
28

4.3.1 Best Practice 1-11: Vehicle Profile Improvement I - Cab Top Deflector, 

Sloping Hood and Cab Side Flares 

Truck tractor aerodynamic drag reduction options, including cab top deflector, sloping 

hood, and cab side flares, have been introduced into the market. These add-on devices are 

estimated to reduce the aerodynamic drag of medium- and heavy-duty trucks and increase their 

fuel efficiency and reduce GHG emissions.32 Taking into account that these devices reduce 

only a fraction of aerodynamic drag, the estimated potential reductions in modal GHG emissions 

are 1.4%. Although this best practice increases truck weight slightly, the estimated reduction in 

fuel use and GHG emissions takes this into account. 

4.3.2 Best Practice 1-12: Vehicle Profile Improvement II - Closing and 

Covering of Gap between Cab and Trailer or Van, Aerodynamic Bumper, 

Underside Air Baffles, and Wheel Well Covers 

Truck side and underside aerodynamic drag reduction options, including closing and 

covering the gap between a tractor and trailer (or van), aerodynamic bumper, underside air 

baffles, and wheel well covers, are commercially available technologies for medium- and 

heavy-duty trucks. Aerodynamic drag that results from the tractor-trailer gap can be reduced by 

installing gap covering add-on devices. Drag underneath the vehicle can be reduced by 

installing a lower bumper and underside air baffles. Wheel well covers enclose the open space 

between the wheels and the truck body, which streamlines the side of the truck. From the 

results of field tests, combining these options is estimated to reduce energy use and GHG 

emissions.11,32 The estimated potential reductions in modal GHG emissions are 2.4%. 

Although this best practice increases truck weight slightly, the estimated reduction in fuel use 

and GHG emissions takes this into account. 

4.3.3 Best Practice 1-13: Vehicle Profile Improvement III - Trailer or Van 

Leading and Trailing Edge Curvatures 

Truck trailer (or van) aerodynamic drag reduction options, including the improvement of 

their leading and trailing edge curvatures, are commercially available strategies. Aerodynamic 

drag can be reduced by the redesign of leading and trailing edges, such as rounded front corners 

and rounded aft corners.40 The estimated potential reductions in modal GHG emissions are 

1.2%.32 

4.3.4 Best Practice 1-14: Pneumatic Aerodynamic Drag Reduction 

Pneumatic blowing systems are being tested as add-on devices that reduce aft-end 
29

aerodynamic drag. This type of system blows air from slots at the rear of the trailers of 

heavy-duty vehicles in order to smooth air flow over the trailer surfaces and reduce aft-end 

aerodynamic drag. This results in reduction in vehicle fuel energy requirements. From the 

results of full-scaled tests, this system reduces energy use for an individual truck by 3.9% to 

4.8%.32,41-42 However, based on the results of field tests, some truck configurations, such as the 

dimensions of the tractor-trailer gap, may inhibit the reduction of aerodynamic drag achievable 

via this system.43 This best practice is suitable for combination trucks that have van trailers, 

which are a portion of the total truck fleet. Therefore, the estimated potential reductions in 

modal GHG emissions are 2.2%. If used in combination with another best practice, such as 

Best Practice 1-12, there may be a negative synergistic effect in that the total improvement in 

aerodynamics is less than the linear sum of improvements from individual practices. 

4.3.5 Best Practice 1-15: Planar Boat Tail Plates on a Tractor-Trailer 

Planar boat tail plates are being tested as add-on devices that reduce aft-end aerodynamic 

drag. These devices are rectangular plates mounted to the after-end of a trailer in an attempt to 

reduce the wake of trucks. The formation of a wake requires energy; thus, reducing the wake 

can energy consumption. From a full-scaled test for a tractor-van trailer, this practice 

significantly reduces aerodynamic drag, and it was found to reduce average energy use by 

approximately 8.3% over a 10,000 mile trip.44 This best practice is suitable for combination 

trucks that have van trailers, which are a portion of the total truck fleet. Therefore, the 

estimated potential reductions in modal GHG emissions are 3.8%. The drawback of this 

practice is that it may interfere with loading and unloading operations, depending on the design. 

4.3.6 Best Practice 1-16: Vehicle Load Profile Improvement 

Aerodynamic drag can be reduced by the use of a streamlined load profile for a trailer, 

which is a low-tech option. This practice keeps the load profile of a trailer as low as possible 

and secures tarpaulins to smooth air flow and reduce energy use.11 The estimated potential 

reductions in modal GHG emissions are 0.4%. The drawback of this practice is that extra 

work for loading and unloading operations may be required. 

4.4 Tire Rolling Resistance Improvement 

Tire rolling resistance refers to a frictional effect associated with the contact of the tread 

of the tire with the road surface, and the flexing of the tread. Given that many trucks have a 

large number of tires in contact with the road (e.g., 18 wheels), this effect can be significant. 

Thus, rolling tire resistance is an important component of the total engine power demand on a 
30

truck. Rolling resistance can be reduced by avoiding under-inflation of existing tires (to reduce 

unnecessary flexing), substituting one wide-tire for a pair of dual tires (leading to a net reduction 

in total tread area, sidewall flexing, or both), use of alternative tire materials to reduce rolling 

resistance, or use of pneumatic blowing. Each of these are discussed. To the extent that 

rolling resistance can be reduced, total engine power demand is also reduced. This, in turn, 

leads to reductions in fuel use and exhaust CO2 emission from the truck. 

4.4.1 Best Practice 1-17: Automatic Tire Inflation Systems 

With properly inflated tires, tire rolling resistance is decreased and fuel use is reduced 

compared to under-inflation. Automatic tire inflation (ATI) systems are commercially available 

and are intended to keep vehicle tires properly inflated. These systems continually monitor and 

adjust the level of pressurized air in tires. The estimated potential reductions in modal GHG 

emissions are 0.6%.11,45 

4.4.2 Best Practice 1-18: Wide-Base Tires 

Combination trucks usually have two sets of dual tires at each end of an axle. Dual tires 

are heavy and also produce high rolling resistance. Single wide-base tires, which are 

commercially available products, can replace these dual tires. Wide-base tires that have lower 

weight (e.g., there are only two sidewalls for one tire, versus four sidewalls for two tires) and 

produce lower rolling resistance reduce energy use. From the results of interstate field tests, 

using wide-base tires can increase fuel economy for a typical long-haul combination truck by 

3%.11,32,46 This best practice is suitable for combination trucks that have van trailers, which are 

a portion of the total truck fleet. Therefore, the estimated potential reductions in modal GHG 

emissions are 2.0%. By using single instead of dual tires, there is a need for increased attention 

to tire inflation pressure for safety reasons. 

4.4.3 Best Practice 1-19: Low-Rolling-Resistance Tires 

Compared to conventional tires, lower rolling resistance tires are commercially available 

from most tire companies, and trucks with these tires are more fuel-efficient because of the 

reduction of rolling resistance by the use of new materials, such as the combination of silica and 

synthetic elastomer.47 Based on the results of interstate field tests, using low-rolling-resistance 

tires can reduce energy use by 2.9%.32 Such tires could be used on any truck. Therefore, the 

estimated potential reduction in modal GHG emissions is 2.8%. The fuel saving advantage 

tends to be reduced when these low-resistance tires wear down. 
31

4.4.4 Best Practice 1-20: Pneumatic Blowing to Reducing Rolling Resistance 

Pneumatic blowing is a technology under development that can reduce aerodynamic drag 

(Best Practice 1-14, Pneumatic Aerodynamic Drag Reduction) and tire rolling resistance. The 

system for Best Practice 1-14 can also blow streams of air under the truck. Since tire rolling 

resistance is directly proportional to loaded weight on the wheels times the tire friction 

coefficient, these air streams provide a slight lift that unloads the tires and reduces tire rolling 

resistance.48 Based on the results of full-scaled tests, this technology reduce energy use for a 

combination truck by 1.2% when accounting for the energy to compress and deliver pressurized 

air versus the benefits of reduced rolling resistance.32,42 This best practice is suitable for 

combination trucks that have van trailers, which are a portion of the total truck fleet. Therefore, 

the estimated potential reductions in modal GHG emissions are 0.5%. However, this system 

may slightly increase dust pollution by dislodging particles on the road surface. 

4.5 Hybrid Propulsion ― Best Practice 1-21: Hybrid trucks 

Stop-and-go truck driving includes a fraction of idling conditions during which the truck 

base engine consumes fuel but produces no economically useful output (e.g., movement of goods, 

or repositioning of the truck to a new location). Hybrid propulsion systems, which are in the 

development stage for trucks, shut off the engine under idling conditions or situations of low 

engine power demand. They also recover or recycle energy from braking and deceleration. 

Trucks that have high fractions of stop-and-go freight transport activities within their driving 

cycles, such as medium-duty package and beverage delivery trucks, are good candidates for 

hybridization. Most heavy-duty trucks and a fraction of medium-duty trucks are long-haul 

trucks. Long-haul trucks have a lower proportion of short-term idling or low engine power 

demand in their duty cycles because of traffic conditions or frequency stops compared to 

medium-duty trucks in local services. Based on the results of hybridization effects modeling, 

medium-duty trucks in local service (e.g., delivery) can reduce energy use by 41.5%.

20,49 This 

best practice is considered to be more suitable for medium duty trucks because of the 

characteristics of their duty cycles. Therefore, the estimated potential reductions in modal 

GHG emissions are 3.4%. The effect of additional weight associated with the battery set is 

accounted for in the estimates given here. A key disadvantage is the initial capital cost and 

uncertainty regarding the life of the battery pack and battery replacement costs. 

4.6 Weight Reduction ― Best Practice 1-22: Lightweight Materials 

The energy consumed by a truck depends on many factors, including the tare weight of 

the vehicle itself. Substitution of light-weight materials for conventional materials (e.g., steel) 
32

can reduce the total vehicle weight. High-strength, lightweight materials include aluminum, 

plastics, high strength steel alloys, and others. Since fuel use is directly proportional to truck 

weight, trimming 3,000 pounds (about 4% of truck weight) from a heavy-duty truck by using 

lighter-weight components improves fuel economy by 3%, and every 10% reduction in truck 

weight is estimated to reduce fuel use by 5 to 10%.50 In one study, mass reduction was 

estimated to reduce energy use by 4.8% or more.51 The estimated potential reductions in modal 

GHG emissions are 4.6%. However, current light-weight materials are costly and with no 

satisfied material characteristics. Further research and development for advanced materials are 

needed. 

4.7 Transmission Improvement 

Traditional truck transmissions are designed to provide discrete engine-wheel speed 

ratios. Transmission operation is associated with mechanical losses, leading to additional fuel 

consumption of the vehicle. Improving transmission systems, such as by using advanced 

high-efficiency transmission technologies and low-viscosity transmission lubricants, have the 

potential to reduce mechanical losses and reduce energy consumption.5,32 

4.7.1 Best Practice 1-23: Advanced Transmission 

Advanced transmission technologies, such as the optimization of transmission 

engine-wheel speed ratios and reduction of mechanical losses, can reduce truck fuel use. A 

traditional transmission has a fixed number of gears that do not often achieve maximum 

efficiency. A continuously variable transmission (CVT) has belt-connected pulleys that can 

optimize transmission speed-load conditions and reduce fuel consumption. Mechanical losses 

in a transmission can be reduced by the reduction of gear surface roughness, the use of 

low-friction coatings, the use of new gear materials, and the use of a lock-up torque converter 

that eliminates slip at cruising speed. In one study, advanced transmission and improved 

lubricants were estimated to reduce energy use by 2%.51 Since improved transmission 

lubricants, which is described in Section 4.7.2, is estimated to reduce energy use by 1%,52 this 

practice is estimated to reduce fuel use by 1.0% on average for all conditions. The estimated 

potential reductions in modal GHG emissions are 1.0%. Driver training may be needed to 

avoid the confusion because the sound of the engine with traditional transmissions changes for 

acceleration operations but the sound of the engine with improved transmission does not change 

in the condition of acceleration. 
33

4.7.2 Best Practice 1-24: Transmission Friction Reduction through 

Low-Viscosity Transmission Lubricants 

Lubricants can reduce gear contact friction in transmissions, but they also reduce fuel 

efficiency because of their viscosity.53 Low-viscosity transmission fluid can be adopted to 

decrease transmission friction and also reduce fuel consumption. Assuming that all trucks can 

adopt low-viscosity transmission fluids, this practice is estimated to reduce energy use by 

approximately 1.0%.52 The estimated potential reductions in modal GHG emissions are 0.9%. 

Low-viscosity transmission fluid typically costs more than conventional lubricants. 

4.8 Diesel Engine Improvement 

The overall fuel efficiency of a diesel engine of a Class 8 trucks with a typical long-haul 

driving cycle is about 40%. The remaining 60% of fuel energy becomes waste heat. Some 

factors limit diesel engine efficiency, such as engine friction, peak cylinder pressure, combustion 

efficiency, and engine thermal management.53 Technologies that can improve the impacts of 

these factors can reduce fuel consumption significantly.5,32,51,53 

4.8.1 Best Practice 1-25: Engine Friction Reduction through Low-Viscosity 

Engine Lubricants 

Some energy losses in an engine are because of mechanical friction. Reduction in 

internal engine friction can be achieved using improved lubricants. Low-viscosity engine 

lubricants are made from synthetic or mineral oil blends for the purpose of reducing internal 

engine friction. Low-viscosity engine lubricants can reduce energy use by 1.9%.32,52 The 

estimated potential reductions in modal GHG emissions are 1.8%. Low-viscosity engine fluid 

typically costs more than conventional lubricants. 

4.8.2 Best Practice 1-26: Increased Peak Cylinder Pressures 

Diesel engine thermal efficiency is proportion to the peak pressures that can be achieved 

in the engine cylinders. However, the peak cylinder pressures are constrained by the strength 

and durability of the engine materials over the design service life of the engine. Measures that 

result in better materials that enable higher peak pressures can lead to higher engine 

efficiency.53-54 The development of new materials and associated new engine designs is an 

emerging area of work. This practice is commercially available and it is estimated to reduce 

energy use for heavy-duty trucks by 3.9%.51 Although this practice is likely to be applicable to 

all diesel engines in the long-run, its initial application is expected to focus on heavy-duty 
34

trucks124 Therefore, the estimated potential reductions in modal GHG emissions are 3.1%. 

4.8.3 Best Practice 1-27: Improved Fuel Injectors 

Incorrect fuel injection causes a reduction of combustion efficiency and an increase of 

emissions. The improvement of fuel injection via better control is expected to reduce truck fuel 

use. For example, advanced fuel injection systems, such as electronic unit injectors or common 

rail injectors with increased fuel injection pressure, are estimate to result in better control of the 

fuel injection rate and injection timing, and to produce finer vaporization of the fuel 

spray.32,51,54-55 The estimated potential reductions in modal GHG emissions are 5.5%. 

However, a drawback of higher injection pressures is the need to have stronger fuel-injection 

system and other engine components that withstand the higher pressures. The improved high 

pressure injectors may have leakage problem after a period of operation time. Regular 

diagnosis is needed to identify and address this problem. 

4.8.4 Best Practice 1-28: Turbocharged, Direct Injection to Improved 

Thermal Management 

Turbocharging utilizes the exhaust air flow from engine to drive a turbine and then drive 

an air compressor to increase engine air intake. Advanced turbochargers that drive more air 

into the cylinder increase combustion efficiency and allow direct injectors to inject more fuel 

into cylinders. Most heavy-duty trucks have turbochargers, but medium-duty trucks do not. 

In one study, turbocharged, direct injection diesel engines was estimated to increase 

medium-duty truck fuel economy by 5 to 8%.51 Taking account that this practice is suitable for 

medium-duty trucks, the estimated potential reductions in modal GHG emissions are 0.8%. 

4.8.5 Best Practice 1-29: Using Thermoelectric Technology to Recovery Waste 

Heat 

Overall engine thermal efficiency can be increased if new materials and technologies can 

be developed and implement for improved thermal management. An example is the 

conversion of engine waste heat to electrical energy. Such systems are not commercially 

available and are undergoing development. Combining thermoelectric materials and advanced 

heat exchangers may recover waste heat in order to produce electricity. Based on the results of 

laboratory tests, a thermoelectric generator with a heat exchanger is projected to reduce energy 

use by 6.5%.56 The intended application of this best practice is for heavy duty trucks. The 

estimated potential reductions in modal GHG emissions are 5.2%.51 Thermoelectric converter 

technology needs further research and development (R & D) to increase its currently low 

conversion efficiency. The estimates reported here presume that such R & D will be successful. 
35

4.9 Accessory Load Reduction 

Truck auxiliary loads, such as the air-conditioning compressor, air compressor, fans, 

hydraulic pump, and coolant pump, are typically gear- or belt-driven and thus directly consume 

energy provided by the base engine. Full electrification of these mechanically driven 

auxiliaries can reduce engine load and use less energy.32 Using fuel cell units as the electricity 

source for electric auxiliaries can reduce more energy than using a generator to power electric 

auxiliaries.32,49 

4.9.1 Best Practice 1-30: Electric Auxiliaries 

Most mechanical auxiliaries operate whenever truck base engines are running, which 

waste energy when the auxiliaries are not needed. The replacement of gear- or belt-driven 

auxiliaries by electrically driven systems can decouple mechanical loads from the base engine 

and reduce energy use. Since the average engine loads from mechanical auxiliaries are higher 

than those from a small generator that supplies electricity to electric auxiliaries, base engine fuel 

can be reduced. Based on a full-scale test of a prototype truck that used a small generator to 

produce electricity, full electrification of auxiliaries reduced fuel use by 2%.57 The estimated 

potential reductions in modal GHG emissions are 1.4%.32 The smaller generator for this 

practice may need pollution control devices in order to comply with future emissions standards. 

4.9.2 Best Practice 1-31: Fuel-Cell-Operated Auxiliaries 

Fuel cells are an emerging technology for converting chemical energy in a fuel directly to 

electricity. The advantage of fuel cells over conventional engine and alternator technology is 

that they have substantially higher thermal efficiency. Among the barriers to practical use of 

fuel cells are the cost of precious materials used for their internal components and the need for 

conversion of readily available transportation fuels to a form that can be processed by the fuel 

cell. This best practice is based on the use of a small fuel cell sized to provide the requirements 

of all of the electrical auxiliaries, and is complementary to a base diesel engine used to supply 

the energy requirements of the power train. This best practice uses electrically-operated 

auxiliaries similar to those of Best Practice 1-30 (see Section 4.9.1). This system could be 

available in the market by 2012 with acceptable capital cost, according to some estimates.32,49 

The estimated potential reductions in modal GHG emissions are 5.5%. This practice has high 

thermal efficiency, but further R & D is needed in order to reduce cost. 
36

4.10 Modifications in Driver Operational Practice ―Best Practice 1-32: Truck Driver 

Training Program 

The behavior of truck drivers can significantly impact fuel efficiency. For example, 

unnecessarily frequent shifting, rapid acceleration and stops and starts increase fuel use.58 

Drivers can be encouraged to modify behaviors that unnecessarily increase fuel use via training 

programs that aim to convey better skills and habits. Furthermore, driver performance can be 

monitored and incentives can be provided to reward preferred behaviors. In one study, driver 

training and monitoring were estimated to reduce energy use by 3.8%.11 In several other studies 

in Europe and Canada, the effect of driver training, monitoring and incentive programs was 

estimated to increase fuel economy by 5 to 20%.11,58-59 Taking into account that a fraction of 

truck companies are likely to adopt these programs,11 the estimated potential reductions in modal 

GHG emissions are 3.1%. 

4.11 Alternative Fuel ―Best Practice 1-33: B20 Biodiesel Fuel 

An alternative fuel has the potential to reduce GHG emissions, although it may not lead 

to overall reductions in energy consumption. A fuel that is derived from renewable resources 

(e.g., biomass) can lead to reductions in the net amount of carbon dioxide released to the 

atmosphere. However, the substitution of one fuel for another leads to changes in emissions not 

only for the truck, but also for the entire fuel life cycle. Therefore, comparisons of different 

fuels must be done on a life cycle basis, which is the approach taken here. 

Some alternative fuels that have a lower ratio of carbon-to-hydrogen can also lead to 

reductions in the net amount of carbon dioxide released while trucks are operating. However, 

these fuels may not have reductions in the net amount of CO2 emissions on a life-cycle basis. 

For example, liquefied natural gas (LNG) contains less carbon per unit of heating value than 

diesel fuel, thereby reducing tailpipe CO2 emissions by approximately 15%. However, when 

fuel recovery, processing, transportation, and distribution are taken into account, the life-cycle 

CO2 emissions for LNG are estimated to increase by approximately 4% compared to that of 

petroleum diesel.60 For this reason, LNG is not further considered as a useful alternative fuel 

for purposes of GHG emissions reductions. However, if the fuel cycle emissions are reduced, 

then LNG could be reconsidered in the future. 

Biodiesel fuels are produced based on vegetable oils or animal fats that have been 

transesterized in order to achieve a viscosity similar to that of petroleum diesel. B100 refers to 

a biodiesel blend stock comprised of 100% vegetable or animal fat derived fuel. The carbon in 

B100 is essentially from renewable resources, depending on the configuration of the fuel 

production process. Thus, resultant CO2 emissions from combustion of biodiesel do not 
37

contribute to a net increase in ambient CO2 concentrations, assuming that the amount of carbon 

sequestered to produce biofuels is equal to that emitted. However, under the current fuel 

infrastructure in the U.S., a significant portion of energy consumed in the production of biodiesel 

is based on consumption of petroleum diesel (e.g., for transport) or emissions associated with 

electrical energy consumption. Furthermore, B100 is not practical for direct use because of 

issues with handling. Instead, a more common approach is to use a blend of 20% blend stock 

and 80% petroleum diesel, referred to as B20. This blend has many of the handling advantages 

of petroleum diesel, while also offering some reduction in net CO2 emissions. 

The life-cycle CO2 emissions coefficient is estimated to decrease by 0.0069 tons CO2 eq. 

per 106 BTU for B20 versus petroleum diesel. This alternative fuel is commercially available in 

limited amounts, but interest in biodiesel appears to be increasing. The estimated potential 

reductions in modal GHG emissions are 4.4%.61-64 The estimated potential modal increase in 

energy use from substitution of B20 for petroleum diesel is 4.3%.61 

The potential disadvantages of biodiesel fuel depend on the percentage of blend stock 

used, the source of the blend stock, and whether the blend stock complies with the ASTM 

standard for B100. For B20 biodiesel based on a compliant B100 blend stock, the 

disadvantages to the vehicle operator are likely to be minor in warm climates, and include the 

need to replace and possibly enlarge the fuel filter and to manage fuel storage so as to avoid 

biofouling. In colder climates, there are potential problems with coagulation of biofuel because 

of its higher cloud point compared to petroleum diesel. However, the severity of this problem 

also depends on the percentage of blend stock used. Because biodiesel has a lower energy 

density than petroleum diesel, vehicle operators may experience a modest (approximately 5%) 

reduction in maximum power. 

4.12 Summary of Potential Best Practices for the Truck Mode 

All 33 potential best practices, sorted by 11 subgroups, for the truck mode are 

summarized in Table 4-1. They are in table format for the convenience of readers. 

4.13 Comparisons of Modal GHG Emissions Reductions for the Best Practices 

Figure 4-1 illustrates the variability among the potential best practices with respect to 

estimated reductions in modal GHG emissions. 

There percentage reductions in modal GHG emissions range from 0.2 to 5.5 percent 

when comparing individual best practices. However, these percentage reductions cannot be 

summed to obtain a total GHG emission reduction. Some best practices are mutually exclusive 

or have interactions with others. Furthermore, some practices may have substantial technical or 
38

Table 4- 1. List and Description of Potential Best Practices for the Truck Mode. 

Subgroup Type of 

Strategies Description 

Technology 

1-1. Off-Board Truck Stop Electrification

Off-board truck stop electrification is a commercially available system 

that can avoid the need for idling of the truck base engine while a truck is 

parked at a truck stop. This external system enables a truck driver to 

switch off the base engine by connecting the truck to a specially designed 

service module. This module provides heating, air conditioning and 

electricity to the truck cab, and it is installed temporarily through a 

window of the truck. This system is reported to consumes less energy 

than the base engines and emits less CO2.

26-29 A commercially available 

example of this is the IdleAire system.30 The estimated potential 

reduction in modal GHG emissions is 0.3%. The operation charge for 

this system is approximately $1.25~$1.50 per hour per truck.5 

Technology 

1-2. Truck-Board Truck Stop Electrification 

Truck-board truck stop electrification, also called a shore power truck 

electrified parking system, is a commercially available system that can 

avoid the need for idling of the truck base engine while a truck is parked 

at a truck stop. In contrast to Best Practice 1-1, which involves an 

external service module, truck stop electrification can be as simple as 

connecting the truck to a shore-based power supply via an electrical 

cable. This type of system is effective in situations where the heating, 

ventilation and air conditioning (HVAC) system of the sleeper cab is 

entirely electrically operated and, thus, is independent of the base engine. 

This system enables a truck driver to switch off the base engine by 

connecting the truck to the electrical grid. Thus, the energy use and 

emissions for this best practice are associated with those of the power 

grid. Compared to use of the base engine, this type of electrification is 

reported to consume less energy and emits less CO2.

28,29,31 The 

estimated potential reduction in modal GHG emissions is 0.4%. The 

operation charge for this system is $0.5~$1.00 per hour per truck.5

 

Anti-Idling 

Technology 

1-3. Auxiliary Power Units

Auxiliary power units (APUs) are commercially available systems that 

can avoid the need for idling of a truck’s base engine wherever a truck 

driver parks for rest. An APU is installed externally on a truck and 

consists of a small diesel engine that provides power for an HVAC 

system and electrical outlets that service the sleeper cab. APUs are 

advertised as consuming less fuel under typical load conditions than the 

base engine. There are some practical questions regarding whether 

APUs are sufficiently quiet for use while a driver is sleeping, especially 

if they cycle on and off to meet intermittent A/C compressor demand, 

regarding their ability to rapidly cool-down the cab on very hot days, and 

their actual fuel efficiency relative to base engines. Based on available 

information, APUs are estimated to consume less diesel fuel than the 

base engine and emits less CO2.

27,32 The estimated potential reduction 

in modal GHG emissions is 2.1%. The estimated incremental capital 

cost is $8,279.31

Continued on next Page 
39

Table 4-1. Continued 

Subgroup Type of 

Strategies Description 

Technology 

1-4. Direct-Fired Heaters

Direct-fired heaters are commercially available systems for heating a 

sleeper cab by burning diesel fuel. Heat from combustion gases passes 

through a heat exchanger that warms the air inside the sleeper cab. In 

addition, these heater systems can be configured to provide heat for the 

base engine to maintain readiness for base engine restart in cold weather. 

Unlike the previous three best practices described above, this system is 

only applicable to heating in cold weather and does not provide cooling 

in hot weather. Furthermore, this system does not provide electrical 

power; instead, electrical power is drawn from the truck’s existing 

battery. Direct-fired heaters are reported to consume less diesel fuel 

than the base diesel engines and to emit less CO2. The estimated 

potential reduction in modal GHG emissions is 1.1%.27 

Anti-Idling 

Technology 

1-5. Direct-Fired Heaters with Thermal Storage Units

Direct-fired heaters are used to heat both the sleeper cab and engine 

when a truck is idling. Thermal storage systems consist of a phase 

change material that can be heated or cooled from the truck cab air 

conditioning unit or heating system while the base engine is operating. 

These systems are demonstrated. The thermal storage system can be 

used as a means of providing warm or cool air via a heat exchanger and a 

blower unit to the sleeper cab for up to eight hours when the base engine 

is off. In order to supplement the heating capability, thermal storage 

systems can be coupled with direct-fired heaters to store more thermal 

energy that is available for warming interior cabin air even when the 

direct-fired heater is not operating. This system supplies heating and 

cooling, but no electrical power, to the sleeper compartment when the 

base engine is off. Furthermore, similar to Best Practice 1-4, this 

system does not provide electrical power; instead, electrical power is 

drawn from the truck’s existing battery. The combination of direct-fired 

heaters and thermal storage units is reported to consume less energy than 

the base engines and to reduce CO2 emissions. The potential reduction 

in modal GHG emissions may be as large as 2.9%.27 

Air 

conditioning 

System 

Improvement 

Technology 

1-6. Enhanced Air Conditioning System I - for Direct Emissions

Direct GHG emissions of current HFC-134a mobile A/C systems are due to 

refrigerant leakage. Enhanced mobile A/C systems, which are undergoing 

testing, can reduce direct GHG emissions by reducing the leakage rate of 

the commonly used HFC-134a refrigerant. The refrigerant leakage 

rates of these system may be decreased through the use of low permeable 

hoses, improved hose ends and connectors, and improved compressor shaft 

seals.12,33-35 HFC-134a emission from mobile A/C system is reported to 

be approximately 8.5 g CO2 eq. per mile, including 6 g CO2 eq. per mile

from direct leakage in normal operation conditions. Other emission is 

because of accidental release and dismantling emissions. Enhanced A/C 

systems are estimated to reduce direct leakage in normal operation 

conditions by 50%, which is about 3 g CO2 eq. per mile. The estimated 

potential reduction in modal GHG emissions is 0.9%.33 

Continued on next Page
40

Table 4-1. Continued 

Subgroup Type of 

Strategies Description 

1-7. Enhanced Air Conditioning System II - for Indirect Emissions

Indirect GHG emissions of mobile A/C systems are additional exhaust CO2

emissions that result from the engine load due to operation of mobile A/C

system. Mobile A/C systems operation time is about 34% of truck 

operation time. Based on the assessment results of a California 

government report that indirect emissions of running HFC-134a A/C 

systems are about 7.35 g CO2 eq. per mile, average indirect emissions are 

about 2.5 g CO2 eq. per mile in truck operation time. Enhanced A/C 

systems for reducing indirect GHG emissions are commercially available. 

These systems can decrease base engine load requirements from mobile 

A/C systems by replacing fixed displacement compressors (FDCs) with 

externally controlled variable displacement compressors (VDC), using 

improved control systems, and using improved condensers and 

evaporators. By reducing the engine load requirements, exhaust CO2

emissions for powering A/C system is reported to be reduced by 

25%.33,36-37 The estimated potential reduction in modal GHG emissions is 

0.2%. 

Technology 

1-8. Alternative Refrigerants - CO2

The GWP of leaking refrigerant can be reduced by using an alternative low 

GWP refrigerant. One of alternative low GWP refrigerant is CO2, which 

is called R744 while as a refrigerant. The current widely used refrigerant, 

HFC-134a, has GWP = 1,300, whereas CO2 has GWP = 1. The 

abundance of CO2 supply from many industries is also the advantage of 

this alternative refrigerant. Another advantage is that recovery and 

recycling of CO2 is not difficult. Vehicle industry is developing 

CO2-based air conditioning systems, and engineers are working to improve 

the reliability and efficiency of systems that use CO2 as refrigerant.12,33-34,36

The estimated potential reduction in modal GHG emissions is 2.5%.33 

Air 

conditioning 

System 

Improvement 

Technology 

1-9. Alternative Refrigerants - HFC-152a

1,1-difluoroethane (C2H4F2), I is known as HFC-152a, is another promising 

low GWP refrigerant. HFC-152a has a lower GWP (120) than that of 

HFC-134a (1,300). The transition from one HFC to another, such as from 

HFC-134a to HFC-152a, would be relatively easy (compared a transition to 

CO2) since these two refrigerants have similar thermodynamic 

characteristics and A/C system components would need less modification.

However, its flammability causes additional safety considerations and the 

needs of risk mitigation approaches. For example, the evaporator may 

need to be located far from the passenger compartment. The design of the 

secondary heat exchange loop can enhance the safety of this system. 

HFC-152a systems is expected to be widely available within 4

years.12,33-34,36 The estimated potential reduction in modal GHG emissions 

is 2.4%.33 

Continued on next Page 
41

Table 4-1. Continued 

Subgroup Type of 

Strategies Description 

Air 

conditioning 

System 

Improvement 

Technology 

1-10.Alternative Refrigerants - HC

Propane has been proposed as an alternative refrigerant for vehicle air 

conditioners. Propane is called R290 as an alternative refrigerant and has 

a lower GWP (20) than that of HFC-134a (1,300).38 This propane based 

refrigerant system has had more than 400,000 accumulated unit-years of 

operating experience in Australia. However, a propane based refrigerant 

system uses about 10% more energy for the operation of vehicle air 

conditioners and increases indirect GHG emissions, thus there is some 

tradeoff.34 Furthermore, there is concern regarding its safety because of 

the flammability of propane and the risk mitigation approaches are 

needed.36 The volatile organic compound properties of propane that 

increase tropospheric ozone formation is another concern.34,36,38 If such 

systems are accepted for use in the U.S., the estimated potential reduction 

in modal GHG emissions is 2.5%.33 

Technology 

1-11. Vehicle Profile Improvement I - Cab Top Deflector, Sloping Hood 

and Cab Side Flares

Truck tractor aerodynamic drag reduction options, including cab top 

deflector, sloping hood, and cab side flares, have been introduced into the 

market. Cab deflectors are designed at the same height as the trailer. 

Flares or fairings on the side of cabs cover batteries, fuel tank and 

suspension. These add-on devices are estimated to reduce the 

aerodynamic drag of medium- and heavy- duty trucks and increase their 

fuel efficiency by 2.0%. Taking into account that these devices reduce 

only a fraction of aerodynamic drag, the estimated potential reduction in 

modal GHG emissions is 1.4%. The estimated incremental capital cost is 

$750.32 

Aerodynamic 

Drag 

Reduction 

Technology 

1-12. Vehicle Profile Improvement II - Closing and Covering of Gap 

Between Tractor and Trailer, Aerodynamic Bumper, Underside Air 

Baffles, and Wheel Well Covers

Truck side and underside aerodynamic drag reduction options, including 

closing and covering the gap between a tractor and trailer (or van), 

aerodynamic bumper, underside air baffles, and wheel well covers, are 

commercially available technologies for medium- and heavy-duty trucks. 

Aerodynamic drag that results from the tractor-trailer gap can be reduced 

by installing gap covering add-on devices, such as cab extenders, trailer 

splitter plates, gap vortex stabilizer and gap seals. Drag underneath the 

vehicle can be reduced by installing lower bumper and underside air 

baffles. Wheel well covers enclose the open space between the wheels 

and the truck body, which streamlines the side of the truck. From the 

results of field tests, combining these options are estimated to reduce 

energy use and decrease GHG emissions.11,32 Taking into account that 

these devices reduce a fraction of aerodynamic drag, the estimated 

potential reduction in modal GHG emissions is 2.4%. The estimated 

incremental capital cost is approximately $1,500.32 

Continued on next Page 
42

Table 4-1. Continued 

Subgroup Type of 

Strategies Description 

Technology 

1-13. Vehicle Profile Improvement III - Trailer Leading and Trailing Edge 

Curvatures

Truck trailer (or van) aerodynamic drag reduction options, including the 

improvement of their leading and trailing edge curvatures, are 

commercially available strategies. Aerodynamic drag can be reduced by 

the redesign of leading edges and trailing edges of trailers or vans, such as 

rounded front corners and rounded aft corners.40 The estimated potential 

reduction in modal GHG emissions is 1.2%. The estimated incremental 

capital cost is $500.32,40 

Technology 

1-14 Pneumatic Aerodynamic Drag Reduction

Pneumatic blowing systems are being tested as testing add-on devices that 

reduces aft-end aerodynamic drag. This type of system blows air from 

slots at the rear of the trailers of heavy-duty vehicles in order to smooth air 

flow over the trailer surfaces and reduce aft-end aerodynamic drag. This 

results in reduction in vehicle fuel energy requirements. From the results 

of full-scaled tests, this system reduces energy use for an individual truck

by 3.9% to 4.8%.32,41-42 However, based on the results of field tests, some 

truck configurations, such as the dimensions of the tractor-trailer gap, may 

inhibit the reduction of aerodynamic drag achievable via this system.43

This best practice is suitable for combination trucks that have van trailers, 

which are a portion of the total truck fleet. Therefore, the estimated 

potential reduction in modal GHG emissions is 2.2%. This system is 

expected to be available in 2010 and the estimated incremental capital cost 

is $2,500, but could be as high as $5,250.32,51 

Technology 

1-15 Planar Boat Tail Plates on a Tractor-Trailer

Planar boat tail plates are being tested as add-on devices that reduce 

aft-end aerodynamic drag. These devices are four rectangular plates

mounted to the after-end of a trailer in an attempt to reduce the wake of 

trucks. The formation of a wake requires energy; thus, reducing the wake 

can energy consumption. To maintaining full-functional operation, rigid 

composite sides with a flexible top and bottom are designed, and these 

plates can be folded. From a full-scaled test for a tractor-trailer, this 

practice was found to reduce average energy use by approximately 8.3% 

over a 10,000 mile trip.44 This best practice is suitable for combination

trucks that have van trailers, which are a portion of the total truck fleet. 

Therefore, the estimated potential reduction in modal GHG emissions is 

3.8%. 

Aerodynamic 

Drag 

Reduction 

Operation 

1-16. Vehicle Load Profile Improvement

Aerodynamic drag can be reduced by the use of a streamlined load profile 

for a trailer, which is a low-tech option. This practice keeps the load 

profile of a trailer as low as possible and secures tarpaulins to smooth air 

flow. For example, a suggested method for flatbed trailers is to arrange as 

low as possible and cover with a tarpaulin. A 2.4% energy reduction was 

reported for properly secured tarpaulins.11 Taking into account that it is 

suitable for combination trucks that have non-van trailers, the estimated 

potential reduction in modal GHG emissions is 0.4%. 

Continued on next Page 
43

Table 4-1. Continued 

Subgroup Type of 

Strategies Description 

Technology 

1-17. Automatic Tire Inflation Systems

With properly inflated tires, tire rolling resistance is decreased and fuel use 

is reduced compared to under-inflation. Automatic tire inflation (ATI) 

systems are commercially available and are intended to keep vehicle tires 

properly inflated. These systems continually monitor and adjust the level 

of pressurized air in tires. Installing ATI systems on a combination truck 

was reported to reduce 97 to 100 gallons of fuel per year, which is about 

1.1 tons GHG emissions reduction per truck per year.11,45 The estimated 

potential reduction in modal GHG emissions is 0.6%. The estimated 

incremental capital cost is $900.5

 

Technology 

1-18. Wide-Base Tires

Combination trucks usually have two sets of dual tires at each end of an 

axle. Dual tires are heavy and also produce high rolling resistance. 

Single wide-base tires, which are commercially available products, can 

replace these dual tires on combination trucks. Wide-base tires that have 

lower weight (e.g., there are only two sidewalls for one tire, versus four 

sidewalls for two tires) and produce lower rolling resistance reduce energy 

use. From the results of field tests, wide-base tires increase fuel economy 

for a typical long-haul combination truck by 3.0% compared to equivalent 

dual tires.11,32,46 This best practice is suitable for combination trucks that 

have van trailers, which are a portion of the total truck fleet. Therefore, 

the estimated potential reduction in modal GHG emissions is 2.0%. New 

trucks with wide-base tires are possibly cheaper than with dual tires, but 

retrofitting existing trucks have higher cost. Averagely, the estimated 

incremental capital cost is $700.32 Increasing the frequency of monitoring

tire pressure is probably needed for adopting wide-base tires. 

Tire Rollin 

Resistance 

Improvement 

Technology 

1-19. Low-Rolling-Resistance Tires

Conventional tires have high rolling resistance that increases energy use. 

Low-rolling-resistance tires are commercially available from most tire 

companies. Trucks with low-rolling resistance tires are more 

fuel-efficient because of the reduction of tire rolling resistance by the use 

of new materials, such as the combination of silica and synthetic 

elastomer.47 Based on the results of interstate field tests, using 

low-rolling-resistance tires can reduce rolling resistance that reduce energy 

use by 2.9%.32 Such tires could be used on any truck. Therefore, the 

estimated potential reduction in modal GHG emissions is 2.8%. The 

estimated incremental capital cost is $550. The requirements for higher 

inflation pressure and high monitoring frequency may limit the extent of 

their market penetration. 

Continued on next Page 
44

Table 4-1. Continued 

Subgroup Type of 

Strategies Description 

Tire Rollin 

Resistance 

Improvement 

Technology 

1-20 Pneumatic Blowing to Reducing Rolling Resistance

Pneumatic blowing is a technology under development that can reduce 

aerodynamic drag, which is discussed in Best Practice 1-14: Pneumatic 

Aerodynamic Drag Reduction, and tire rolling resistance. The system for 

Best Practice 1-14 that is used for aerodynamic drag reduction, including 

compressor, piping, and blow control, can also be used to blow streams of 

air under trucks. Additional pipes, jets, valves, selective blowing, and 

control system may be needed to blow air under trucks. Since tire rolling 

resistance is directly proportional to loaded weight on the wheels times the 

tire friction coefficient, these air streams provide a slight lift that unloads

the tires and reduces tire rolling resistance.48 Based on the results of 

full-scaled tests, this technology reduce energy use for a combination truck 

by 1.19% when accounting for the energy to compress and deliver 

pressurized air versus the benefits of reduced rolling resistance.32,42 This 

best practice is suitable for combination trucks that have van trailers, which 

are a portion of the total truck fleet. Therefore, the estimated potential 

reduction in modal GHG emissions is 0.5%. If the pneumatic blowing 

system for reducing aerodynamic drag has been installed on a combination 

truck, additional $500 capital cost for extra components would be needed.32

This technology is estimated to be available in 2015 for combination 

trucks.51 

Hybrid 

Propulsion Technology 

1-21. Hybrid Trucks

Stop-and-go truck driving includes a significant fraction of idling 

conditions during which the truck base engine consumes fuel but produces 

no economically useful output (e.g., movement of goods, or repositioning 

of the truck to a new location). Hybrid propulsion systems, which are in 

the development stage for trucks, shut off the engine under idling 

conditions or situations of low engine power demand. They recover or 

recycle energy from braking or deceleration. Fuel use reduction potential

of hybrid trucks is sensitive to their duty cycles. Trucks that have high 

fractions stop-and-go freight transport activities within their driving cycles, 

such as medium-duty package and beverage delivery trucks, are good 

candidates for hybridization. Most of heavy-duty trucks and a fraction of 

medium-duty trucks are long-haul trucks. Long-haul trucks are not 

considered as good candidates because these trucks have a lower 

proportion of short-term idling or low engine power demand in their duty 

cycles because of traffic conditions or frequency stops compared to 

medium-duty trucks in local services. Based on the results of 

hybridization effects modeling, medium-duty trucks in local service (e.g., 

delivery) can reduce energy use by 41.5%.20,49 This best practice is 

considered to be more suitable for medium duty trucks because of the 

characteristics of their duty cycles. Therefore, t he estimated potential 

reduction in modal GHG emissions is 3.4%. Experts in a study estimated 

that this technology would be available in 2010.51,65 The estimated 2005 

incremental capital cost is approximately $7,100, and the estimated 2025 

incremental capital cost is expected to drop to approximately $3,100.49 

Continued on next Page 
45

Table 4-1. Continued 

Subgroup Type of 

Strategies Description 

Weight 

Reduction Technology 

1-22. Lightweight Materials

The energy consumed by a truck depends on many factors, including the 

tare weight of the vehicle itself. Substitution of light-weight materials for 

conventional materials (e.g., steel) can reduce the total vehicle weight. 

High-strength, lightweight materials include aluminum, plastics, and 

others. Since fuel use is directly proportional to truck weight, trimming 

3,000 pounds (about 4% of truck weight) from a heavy-duty truck by using 

lighter-weight components improves fuel economy by 3%, and every 10% 

reduction in truck weight is estimated to reduce fuel use by 5 to 10%.50 In 

one study, mass reduction was estimated to reduce energy use by 4.6% or 

more.51 The estimated potential reductions in modal GHG emissions are 

4.8% or more. The estimated incremental capital cost is $2,000. 

Technology 

1-23. Advanced Transmission

Advanced transmission technologies, such as the optimization of 

engine-wheel speed ratios and reduction of mechanical losses in a 

transmission system can reduce truck fuel consumption. A traditional 

transmission has a fixed number of metal gears to provide several discrete 

speed ratios that do not often achieve maximum efficiency and increase 

fuel use. A continuously variable transmission (CVT) has belt-connected 

pulleys that provide an uninterrupted range of engine-wheel speed ratios to 

optimize transmission speed-load conditions and reduce fuel use. 

Adopting CVT for heavy-duty trucks needs new materials to withstand the 

high torque loads. Mechanical losses in a transmission, such as gear 

contact friction, can be reduced by the reduction of gear surface roughness, 

the use of low-friction coatings, the use of new gear materials, and the use 

of a lock-up torque converter (a mechanical clutch locking the torque 

converter impeller and turbine together to eliminate slip at cruising speed). 

In one study, advanced transmission and improved lubricants were

estimated to reduce energy use by 2%.51 Since improved transmission 

lubricants, which is described in Section 4.7.2, is estimated to reduce 

energy use by 1%,52 this practice is estimated to reduce fuel use by 1.0%

on average for all conditions. The estimated potential reductions in 

modal GHG emissions are 1.0%. This practice is ready introduced into 

market and the estimated incremental capital cost is $1,000.32 . 

Transmission 

Improvement 

Technology 

1-24.Transmission Friction Reduction through Low-Viscosity 

Transmission Lubricants

Lubricants can reduce gear contact friction in transmission, but they also 

reduce fuel efficiency because of their viscosity.53 Low-viscosity 

transmission fluid, made from synthetic or mineral oil blends, are reported 

to decrease transmission friction and also reduce fuel consumption. 

Assuming that all trucks can adopt low-viscosity transmission fluids, this 

practice is estimated to reduce energy use by 1% or more.52 The 

estimated potential reductions in modal GHG emissions are 0.9%. This 

practice is commercially available and the estimated incremental capital 

cost is $500.11,51 

Continued on next Page 
46

Table 4-1. Continued 

Subgroup Type of 

Strategies Description 

Technology 

1-25.Engine Friction Reduction through Low-Viscosity Engine Lubricants 

Some energy losses in an engine are because of mechanical friction. 

Reduction in internal engine friction can be achieved using improved 

lubricants. Low-viscosity engine lubricants are made from synthetic or 

mineral oil blends for the purpose of reducing internal engine friction. 

Low-viscosity engine lubricants can reduce energy use by 1.86% or 

more.32,52 The estimated potential reductions in modal GHG emissions 

are 1.8%. This practice has commercially available products and the 

estimated incremental capital cost is $500.11,51 

Technology 

1-26. Increased Peak Cylinder Pressures

Diesel engine thermal efficiency is proportion to the peak pressures that 

can be achieved in the engine cylinders. However, the peak cylinder 

pressures are constrained by the strength and durability of the engine 

materials over the design service life of the engine. Measures that result 

in better materials that enable higher peak pressures can lead to higher 

engine efficiency.53,54 The development of new materials and associated 

new engine designs is an emerging area of work. This practice is 

commercially available and it is estimated to reduce energy use for 

heavy-duty trucks by 3.9%.51 Although this practice is likely to be 

applicable to all diesel engines in the long-run, its initial application is 

expected to focus on heavy-duty trucks Therefore, the estimated potential 

reductions in modal GHG emissions are 3.1%. The incremental capital

cost is $1,000. 

Diesel Engine 

Improvement 

Technology 

1-27. Improved Fuel Injectors

Incorrect fuel injection causes a reduction of combustion efficiency and an 

increase of emissions. The improvement of fuel injection, such as a better 

control of the fuel injection rate and injection timing, and the production of 

finer vaporization of the fuel spray, is expected to reduce truck fuel use. 

The developments of advanced fuel injection systems, such as electronic 

unit injectors, common rail injectors, electronic unit pump, and electronic 

distribution pump, can improve fuel injection and reduce fuel use. For 

example, common rail injectors with electronic control use high-pressure 

pump to compress fuel into high-pressure accumulation chamber (Rail), 

and the pressure of fuel inside remains constant. Since high-pressure fuel 

is always available for injection, electronic injectors can easily optimize 

fuel injection rate and time, and improves fuel atomization and dispersal. 

Maximizing fuel injection pressure can also enhance fuel reduction by 

improving fuel vaporization and dispersal in the cylinder. 32,51,54-55 The 

estimated potential reductions in modal GHG emissions are 5.5%. The 

estimated incremental capital cost is $1,500. 

Continued on next Page 
47

Table 4-1. Continued 

Subgroup Type of 

Strategies Description 

Technology 

1-28. Turbocharged, Direct Injection to Improved Thermal Management

Diesel engine power is proportional to air intake and fuel. 

Turbocharging utilizes the exhaust air flow from engine to drive a 

turbine and then drive an air compressor to increase engine air 

intake. Advanced turbochargers that drive more air in the cylinder 

increase combustion efficiency and allow direct injectors to inject more 

fuel into cylinders. Most heavy-duty trucks have turbochargers, but 

medium-duty trucks do not. In one study, turbocharged, direct 

injection diesel engines was estimated to increase medium-duty truck fuel 

economy by 5 to 8%.22,51 Taking account that this practice is suitable 

for medium-duty trucks, the estimated potential reductions in modal 

GHG emissions are 0.8%. This practice is already commercially 

available, and the estimated incremental capital cost is $700-1,000.51 Diesel Engine 

Improvement 

Technology 

1-29. Thermoelectric Technology to Recovery Waste Heat

Overall engine thermal efficiency can be increased if new materials and 

technologies can be developed and implement for improved thermal 

management. An example is the conversion of engine waste heat to 

electrical energy. Such systems are not commercially available and are 

undergoing development. Laboratory tests indicate that a small-scaled 

5.54 kW thermoelectric generator can increase fuel economy by 2.2 to 

4.4%. Combining thermoelectric materials and heat exchangers may

recovery waste heat in order to produce electricity. Based on the results 

of laboratory tests, a thermoelectric generator with a heat exchanger is 

projected to reduce energy use by 6.5%.56 The intended application of

this best practice is for heavy duty trucks.51 The estimated potential 

reductions in modal GHG emissions are 5.2%. Those studies estimated 

that this technology would be introduced in 2010 and the estimated 

incremental capital cost is $2,000.51 

Accessory 

Load 

Reduction 

Technology 

1-30. Electric Auxiliaries

Truck auxiliaries, such as air-conditioning compressor, air compressor, 

fans, hydraulic pump, and coolant pump, are gear- or belt-driven by truck 

base engine. Mechanical auxiliaries operate whenever base engines are 

running, which waste energy when the auxiliaries are not needed. The 

replacement of mechanical auxiliaries by electrically driven systems can 

decouple mechanical loads from the base engine and reduce energy use. 

Since the average engine loads from mechanical auxiliaries are higher than

those from a small generator that supplies electricity to electric auxiliaries, 

base engine fuel can be reduced. Based on a full-scaled test of a 

prototype truck that used a small generator to produce electricity, full 

electrification of auxiliaries reduces fuel use by 2%.57 The estimated 

potential reductions in modal GHG emissions are 1.4%.32,51 The 

estimated incremental capital cost is $500. The additional small generator

can also supply electricity for trucks to avoid extended idling, which is 

discussed in Best Practices 1-3, “Auxiliary Power Units.”

Continued on next Page 
48

Table 4-1. Continued 

Subgroup Type of 

Strategies Description 

Accessory 

Load 

Reduction 

Technology 

1-31. Fuel-Cell-Operated Auxiliaries

Fuel cells are an emerging technology for converting chemical energy in a 

fuel directly to electricity. The advantage of fuel cells over conventional 

engine and alternator technology is that they have substantially higher 

thermal efficiency. Among the barriers to practical use of fuel cells are 

the cost of precious materials used for their internal components and the 

need for conversion of readily available transportation fuels to a form that 

can be processed by the fuel cell. This best practice is based on the use of 

a small fuel cell sized to provide the requirements of all of the electrical 

auxiliaries, and is complementary to a base diesel engine used to supply the 

energy requirements of the power train. This best practice uses 

electrically-operated auxiliaries similar to those of Best Practice 1-30 (see 

Section 4.9.1). This system could be available in the market by 2012 with

acceptable capital cost, according to some estimates.32,49 The estimated

potential reductions in modal GHG emissions are 5.5%. The estimated 

incremental capital cost is $500.32,49 

Modifications 

in Driver 

Operational 

Practice 

Operation 

1-32. Truck Driver Training Program

The behavior of truck drivers can significantly impact fuel efficiency. For 

example, unnecessarily frequent shifting, rapid acceleration and stops and 

starts increase fuel use.58 Drivers can be encouraged to modify behaviors 

that unnecessarily increase fuel use via training programs that aim to 

convey better skills and habits. For example, drivers can learn to improve 

their operation skills, such as acceleration and shifting technique. These 

programs can also change driving behaviors, such as route choice and 

unnecessary idling time. Furthermore, driver performance can be 

monitored and incentives can be provided to reward preferred behaviors. 

In one study, driver training and monitoring were estimated to reduce 

energy use by 3.8%.11 In several other studies in Europe and Canada, the 

effect of driver training, monitoring and incentive programs was estimated 

to increase fuel economy by 5 to 20%.11,58-59 For example, a truck fleet

company has reduce energy use by 19% by supplying fuel-saving 

information, using a driver incentive program and regularly reviewing

engine printouts.59 Some other best practices, such as anti-idling 

practices, may inhibit the reduction of energy use for truck driver training 

program. Taking into account that only a fraction of truck companies are 

likely to adopt these programs,11 the estimated potential reductions in

modal GHG emissions are 3.1%. 

Continued on next Page 
49

 Table 4-1. Continued 

Subgroup Type of 

Strategies Description 

Alternative 

Fuel Technology 

1-33. B20 Biodiesel Fuel for Trucks

Biodiesel fuels are produced based on vegetable oils or animal fats that 

have been transesterized in order to achieve a viscosity similar to that of 

petroleum diesel. The potential market share of B20 biodiesel is 

estimated as 51.2% in 2025 based on the potential maximum production 

capacity of biodiesel, which is estimated as 7.8 billion gallons in 2025, and 

the distribution ratio among the truck, rail and water modes.63-64 The 

estimated potential reductions in modal GHG emissions are 4.4%.61-64

Based on life cycle inventories, the production of alternative fuels 

consumes more energy than the production of petroleum diesel. For 

example, processes for producing biodiesel, such as soybean crushing and 

soy oil conversion, are energy intensive.66 The estimated potential modal 

increase in energy use is 4.3%.61

0

1

2

3

4

5

6

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33

Best Practice Number for the Truck Mode 

(1 refers to Best Practice 1-1, 2 refers to Best Practice 1-2, and so on) 

Figure 4- 1. Reductions in Modal GHG Emissions for the Best Practices for the Truck 

Mode 

Modal GHG Emissions Reductions (%) 
50

practical barriers to their acceptance, as described previously. 

4.14 Quantitative Cost Results for Selected Best Practices 

Quantitative cost results for the best practices for which sufficient information was 

available to perform such assessments are summarized in standardized reporting tables, which 

are given in Appendix A. In contrast, assessment results for the best practices which have a 

lack of sufficient information from which to quantify costs are summarized in simplified 

summary tables individually, which are also given in Appendix A. To date, there is sufficient 

information for five best practices upon which to make quantitative assessments. The other 29 

best practices are assessed qualitatively. 

The best practices assessed quantitatively include off-board truck stop electrification, 

auxiliary power units, direct-fired heaters, hybrid trucks, and B20 biodiesel. Table 4-2 

summarizes the quantitative assessment results of modal GHG emissions reductions, modal 

energy use reductions, annualized cost, energy cost saving, net savings, net savings per unit of 

GHG emissions reductions, net savings per unit of energy use reduction, and simple pay-back 

periods for these five selected best practices. 

Four of these five best practices produce net cost savings. These savings are the net 

result of substantial costs offset by substantial savings based on reduced energy usage. For one 

of the best practices, biodiesel, the net saving is negative, indicating that this practice do not pay 

for themselves. Its fuel cost is higher than that for petroleum diesel (based on current typical 

experience) and thus there is a net increase in total costs. 

Overall, there is substantial variability in the cost-effectiveness of these best practices 

when net cost savings are normalized based on the GHG emissions reductions. Direct-fired 

heater appears to be the most cost-effective, whereas the use of B20 biodiesel appears to be the 

least cost effective. However, the APU, hybrid, and biodiesel practices have the potential to 

achieve substantially larger magnitudes of GHG emissions reductions than the other two options. 

Off-board truck-stop electrification could only contribute small magnitude of GHG emissions 

reductions because 80% of truck idling is not at truck stops. Direct-fired heaters can be only 

used in cold weather; therefore, this restriction limits their potential for GHG emissions 

reductions and energy reduction. 
51

Table 4- 2. Summary Table for the Comparison of the Quantitative Cost Results for 

Selected Best Practices for the Truck Modea 

Best Practice Number 1-1 1-3 1-4 1-21 1-34 

Name 

Off-Board 

Truck Stop 

Electrification 

Auxiliary 

Power Units 

Direct-Fired 

Heaters 

Hybrid 

Trucks 

B20 

Biodiesel 

Subgroup Anti-idling Anti-idling Anti-idling Hybrid 

Propulsion 

Alternative 

Fuel 

Responsible Parties 1, 2, 5, 13, 20, 

21, 22 

1, 2, 5, 6, 8, 

11 1, 2, 5 

1, 2, 4, 5, 6, 

8, 9, 12, 16, 

18, 19, 20, 

21, 22 

1, 2, 4, 5, 6, 

12, 14, 16, 

18, 19, 20, 

21, 22 

Target Parties 1, 2, 6, 8 1, 2, 4, 6 1, 2, 4, 6 1, 2, 4, 6, 7 1, 2, 4, 5, 6, 7 

Target GHGs CO2 CO2 CO2 CO2 CO2

Strategy Types Technology Technology Technology Technology Technology 

Developmental Status C C C N C 

Modal GHG Emission 

Reduction 

(106

 ton CO2 eq./year) 

2.4 15.0 7.6 24.5 30.8 

Modal Energy Use 

Reduction (1012 BTU/year) 27 185 94 300 -370.0 

Annualized Costs 

($ 106

/year) 570 3,000 390 2430 3,300 

Annual Energy Cost Saving 

($ 106

/year) 900 3,400 1,740 5,600 0 

Net Saving ($ 106/year) 330 440 1,350 3,190 -3,300 

Net Saving per Unit of 

GHG Emissions Reductions 

($/ton CO2 eq.) 

138 29 178 130 -108 

Net Saving per Unit of 

Energy Use Reduction 

($/ton CO2 eq.) 

12 2.3 14 10.6 N/A b

Simple Pay-back Period 

(years) N/A c 3.2 0.6 2.1 N/A d

a

 These assessments are based on the assumptions that these best practices reach their potential 

maximum market shares in 2025. Cost results are presented only for those best practices for which 

adequate data were available. 

b

 This practice has no energy use reduction due to an increase in energy use, and it has no net saving due 

to high annualized cost and no energy cost saving. c

 There is no pay-back period for this best practice because there is no initial capital cost to uses. 

d

 There is no pay-back period for this best practice because there is no net saving. 
52

5.0. BEST PRACTICES FOR THE RAIL MODE 

This chapter identified and characterizes six potential best practices applicable to the rail 

mode. These best practices are divided into four subgroups, including anti-idling, weight 

reduction, rolling resistance improvement, and alternative fuel. Additional details regarding 

these best practices are in Appendix B. For four of these best practices, sufficient data were 

available to quantify costs. 

5.1 Anti-Idling 

Line-haul locomotives and switchers are often idled for long periods of time to heat or 

cool the cab and to avoid the difficulty of restarting the engine. Over half (55%) of long-haul 

locomotive operation time and approximately 75% of switcher operation time are at idle.67 

During idling, a typical locomotive consumes approximately 3 gallons of fuel per hour.67-68 

Anti-idling technology can reduce long-duration locomotive idling, which in turn reduces fuel 

use and greenhouse gas emissions. 

5.1.1 Best Practice 2-1: Combined Diesel Powered Heating and Auto Engine 

Start/Stop Systems 

A diesel powered heating system can keep the engine block temperature above 100 oF. 

Such systems utilize waste heat from a small diesel engine to heat the main engine and to 

generate electricity using by an alternator. An auto engine start/stop system can shutdown and 

restart both long-haul and switching locomotive engines automatically, based on a 

preprogrammed set of values (e.g., water and coolant temperature, battery voltage, and air brake 

cylinder pressure).69 For example, a driver can set the system to the restart engine and turn on 

heat when the ambient temperature falls below 65° F.70 Both of these systems can be used 

simultaneously to shut down the engine when not needed while also keep the engine warm in 

preparation for a restart and while maintaining batteries in a ready status. This practice, which 

includes both of these systems, can reduce locomotive energy use at idling by approximately 

80%.67 This practice has been demonstrated in terms of installation on a locomotive and 

realization of reduced idling.68 Based on the results of field tests, this practice was found to 

reduce overall long-haul idling time by 70% and overall switcher idling time by 80%.67-68 The 

estimated potential reductions in modal GHG emissions and energy use are both 3.6%. 
53

5.1.2 Best Practice 2-2: Battery-Diesel Hybrid Switching Locomotive 

Battery-diesel hybrid switchers are commercially available locomotives that can replace 

traditional switching locomotives. Traditional switchers typically have 2,000 hp diesel engines. 

Battery-diesel hybrid switchers include a small diesel engine (e.g., 125 to 300 hp) and large 

(60,000 lbs) lead-acid batteries. This small diesel engine is used to charge batteries that 

maintain batteries in a ready status during periods of locomotive non-use. At full load, the 

batteries account for 95% of the horsepower and the small diesel engine accounts for another 5%. 

This hybrid switcher also has an auto start/stop system that contains a microprocessor to 

automatically shut down the small diesel engine during periods of locomotive non-use or when 

the batteries are fully charged based on battery voltage values. From the results of field tests, a 

battery-diesel hybrid switcher was found to reduce daily fuel use by 35 to 57%.71 Since 

switching locomotives are responsible for only a small portion (5%) of total rail fuel use, the 

estimated potential reductions in modal GHG emissions and energy use are both 1.8%. The 

drawback of this practice is that only yard switchers can apply this practice. 

5.1.3 Best Practice 2-3: Plug-In Units 

Plug-in units are commercially available systems that can avoid the need for idling of 

switcher engines while switchers are parked in switching yards. These systems, which require 

both on-board and off-board components, enable locomotive drivers to switch off their diesel 

engines by plugging a locomotive into an external electrical power source. These systems can 

use electricity powered systems to supply heat, circulate and heat coolant and oil, and keep 

batteries charged. The use of a plug-in unit with a switching locomotive is estimated to 

consume 14% less energy than without a plug-in unit, when taking into account avoided direct 

diesel fuel use for operating the locomotive and production of electricity for the external power 

supply.72 Since switching locomotives are responsible for only a small portion (5%) of total rail 

fuel use, the estimated potential reductions in modal GHG emissions and energy use are 0.6% 

and 0.4%, respectively. The drawback of this practice is that only yard switchers can apply this 

practice at appropriately equipped locations. 

5.2 Weight Reduction ― Best Practice 2-4: Lightweight Materials 

The use of lighter-weight components to reduce the weight of locomotives and railcars 

has the potential to reduce fuel use. High-strength, lightweight components include aluminum, 

plastics, and others. Redesigns can also reduce railcar weight and reduce fuel use. For 

example, newly designed coil steel cars have lighter tare weight and extra carrying capacity. 

Redesigned railcars for hauling steel slabs, which are lighter than conventional railcars, can carry 
54

more goods and also reduce energy use. Higher-capacity railcars that have better design and 

that use lightweight materials were introduced by Canadian Pacific Railway.73-74 Based on a 

Canadian study, light-weight coal cars are estimated to reduce energy use by 10 percent, and 

light-weight grain cars are estimated to reduce energy use by 5 percent. The estimated potential 

reductions in modal GHG emissions and energy use are both 4.8%. However, current 

light-weight materials may be costly and may not have satisfactory material characteristics, such 

as strength. Further research and development for advanced materials is needed. 

5.3 Rolling Resistance Improvement ― Best Practice 2-5: Lubrication Improvement 

Some energy expended by the locomotive is lost to wheel-to-rail friction. Reductions in 

wheel-to-rail resistance can be made via improved lubrication. Efficient lubrication systems, 

such as top-of-rail lubrication systems, reduce wheel and rail wear and reduce fuel consumption. 

These systems can avoid wheel slippage by distributing a proper amount of lubricants on the rail, 

so as to reduce wheel-to-rail resistance without causing slippage.75 Based on the results of field 

tests, this practice can reduce fuel consumption by 4% to 6%.76-77 The estimated potential 

reductions in modal GHG emissions and energy use are both 4.0%. 

5.4 Alternative Fuel ― Best Practice 2-6: B20 Biodiesel Fuel for Locomotives 

B20 biodiesel, which is described in Section 4.11.2, is a potential alternative fuel for 

diesel locomotives. Based on a life cycle analysis, the CO2 emissions are estimated to decrease 

by 0.0069 tons CO2 eq. per 106 BTU for B20 compared to petroleum diesel. The estimated 

potential reduction in modal GHG emissions is 5.5%.61,63-64,78-79 Based on life cycle inventories, 

the production of biodiesel consumes more energy than the production of petroleum diesel.66 

The estimated potential modal increase in energy use is 5.3%.61 

. 

5.5 Summary of Potential Best Practices for the Rail Mode 

The six potential best practices for the rail mode are summarized in Table 5-1. They are 

in table format for the convenience of readers. 

5.6 Comparisons of the Modal GHG Emissions Reductions for the Best Practices 

Figure 5-1 illustrates the variability among the potential best practices with respect to 

estimated reductions in modal GHG emissions. 

 Some best practices are mutually exclusive or have interactions with others. Thus, these 

percentage reductions cannot be summed to obtain a total aggregated emission reduction. 
55

Table 5- 1. List and Description of Potential Best Practices for the Rail Mode 

Subgroup Type of 

Strategies Description 

Technology 

2-1. Combined Diesel Powered Heating System and Auto Engine Start/stop 

System

A small diesel powered heating system can keep the engine block 

temperature above 100 o

F. Such systems utilize waste heat from a small 

diesel engine to heat the main engine and to generate electricity using by an 

alternator. An auto engine start/stop system can shutdown and restart both 

long-haul and switching locomotive engines automatically, based on a 

preprogrammed set of values (e.g., throttle position, water and coolant 

temperature, battery voltage, and air brake cylinder pressure), by using a 

microprocessor.69 For example, a driver can set the system to the restart 

engine and turn on heat when the ambient temperature falls below 65° F.70

Both of these systems can be used simultaneously to shut down the engine 

when not needed while also keep the engine warm in preparation for a 

restart and while maintaining batteries in a ready status. This practice, 

which includes both of these systems, can reduce locomotive energy use at 

idling by approximately 80%.67 This practice has been demonstrated in 

terms of installation on a locomotive and realization of reduced idling.16

Based on the results of field tests, this practice was found to reduce overall 

long-haul idling time by 70% and overall switcher idling time by 80%.67-68

The estimated potential reduction in modal GHG emissions and energy use 

are both 3.6%. The estimated incremental capital cost is $28,000 for 

diesel powered heating system and $7,500 for auto engine start stop 

system.68 

Anti-Idling 

Technology 

2-2. Battery-Diesel Hybrid Switching Locomotive

Battery-diesel hybrid switchers are commercially available locomotives that 

can replace traditional switching locomotives. Traditional switchers 

typically have 2,000 hp diesel engines. Battery-diesel hybrid switchers 

include a small diesel engine (e.g., 125 to 300 hp) and large (60,000 lbs) 

lead-acid batteries. The lifetime of these Pb-acid batteries are expected to 

be 10–15 years.69,72 The small diesel engine is used to charge batteries 

that maintain batteries in a ready status during periods of locomotive 

non-use. At full load, the batteries account for 95% of the horsepower and 

the small diesel engine accounts for another 5%. This hybrid switcher 

also has an auto start/stop system that contains a microprocessor to 

automatically shut down the small diesel engine during periods of 

locomotive non-use or when the batteries are fully charged based on battery 

voltage values.71 From the results of field tests, a battery-diesel hybrid 

switcher was found to reduce daily fuel use by 35 to 57%.71 Since 

switching locomotives are responsible for only a small portion (5%) of total 

rail fuel use, the estimated potential reduction in modal GHG emissions is 

1.8%. The estimated capital cost is $200,000. 

Continued on next Page 
56

Table 5-1. Continued 

Subgroup Type of 

Strategies Description 

Anti-Idling Technology 

2-3. Plug-In Units

Plug-in units are commercially available rail yard electrification systems 

that can avoid the need for idling of switcher engines while switchers are 

parked in switching yards. These systems, which require both on-board 

and off-board components, enable locomotive drivers to switch off their 

diesel engines by plugging a locomotive into an external power source of

three-phase AC. These systems can use electricity powered systems to 

supply heat, circulate and heat coolant and oil, and keep batteries charged. 

They are only available at specific locations, such as switching yard. The 

use of a plug-in unit with a switching locomotive is estimated to consume 

14% less energy than without a plug-in unit, when taking into account 

avoided direct diesel fuel use for operating the locomotive and production 

of electricity for the external power supply.72 Since switching locomotives 

are responsible for only a small portion (5%) of total rail fuel use, the 

estimated potential reduction in modal GHG emissions and energy use are 

0.6% and 0.4%, respectively. The estimated capital cost is $8,000. 

Weight 

Reduction Technology 

2-4. Lightweight Materials

The use of lighter-weight components to reduce the weight of locomotives 

and railcars has the potential to reduce fuel use. High-strength, 

lightweight components include aluminum, plastics, and others. 

Redesigns can also reduce railcar weight and reduce fuel use. For 

example, newly designed coil steel cars have lighter tare weight by up to 

55,200 pounds and extra carrying capacity. Redesigned railcars for 

hauling steel slabs, which are lighter than conventional railcars by 20,000 

pounds, can carry more goods and also reduce energy use. 

Higher-capacity railcars that have better design and that use lightweight 

materials were introduced by Canadian Pacific Railway.73-74 Based on a 

Canadian study, light-weight coal cars are estimated to reduce energy use 

by 10 percent, and light-weight grain cars are estimated to reduce energy 

use by 5 percent. The estimated potential reduction in modal GHG 

emissions is 4.8% or more. 

Rolling 

Resistance 

Improvement 

Technology 

2-5. Lubrication Improvement

Some energy expended by the locomotive is lost to wheel-to-rail friction. 

Reductions in wheel-to-rail resistance can be made via improved 

lubrication. Efficient lubrication systems, such as top-of-rail lubrication 

systems, reduce wheel and rail wear and reduce fuel consumption. These 

systems can avoid wheel slippage by distributing a proper amount of 

lubricants on the rail, so as to reduce wheel-to-rail resistance without 

causing slippage.75 Based on the results of field tests, this practice can 

reduce fuel consumption by 4% to 6%, depending on the grade and 

curvature.76-77 The estimated potential reduction in modal GHG emissions 

and energy use are both 4.0%. 

Continued on next Page 
57

Table 5-1. Continued 

Subgroup Type of 

Strategies Description 

Alternative 

Fuel Technology 

2-6. B20 Biodiesel Fuel for Locomotives

B20 biodiesel, which is described in Section 4.11.2, is a potential 

alternative fuel for diesel locomotives. Based on a life cycle 

analysis, the CO2 emissions are estimated to decrease by 0.0069 tons CO2

eq. per 106 BTU for B20 compared to petroleum diesel.61 Although this 

alternative fuel has been a commercially available product for trucks, it is 

being tested for the suitability for the use as locomotive fuel. The 

potential market share of B20 biodiesel is estimated as 64% in 2025 based 

on the potential maximum production capacity of biodiesel, which is 

estimated as 7.8 billion gallons in 2025, and the distribution ratio among 

the truck, rail and water modes.63-64 The estimated potential reduction in 

modal GHG emissions is 5.5%.61,63-64,78-79 Based on life cycle inventories, 

the production of biodiesel consumes more energy than the production of

petroleum diesel.66 The estimated potential modal increase in energy use 

is 5.3%.61

0

1

2

3

4

5

6

2-1 2-2 2-3 2-4 2-5 2-6

Best Practice Number for the Rail Mode 

Figure 5- 1. Reductions in Modal GHG Emissions for the Best Practices for the Rail 

Mode 

Modal GHG Emissions Reductions (%) 
58

The percentage reductions in modal GHG emissions range from 0.6 to 5.5 percent when 

comparing individual best practices. Some best practices are mutually exclusive or have 

interactions with others. Thus, these percentage reductions cannot be summed to obtain a total 

aggregated emission reduction. 

5.7 Quantitative Cost Results for the Selected Best Practices 

Quantitative cost results for the best practices with sufficient information are summarized 

in individualized standardized reporting tables, which are given in Appendix B. In contrast, 

assessment results for the best practices which have a lack of sufficient information from which 

to quantify costs are summarized in simplified summary tables individually, which are also given 

in Appendix B. To date, there is sufficient information for four best practices upon which to 

make quantitative assessments. The other three best practices are assessed qualitatively. 

The best practices assessed quantitatively include combined diesel powered heating and 

start/stop system, battery-diesel hybrid switching locomotive, plug-in units, and B20 biodiesel. 

Table 5-2 summarizes the quantitative assessment results of modal GHG emissions reductions, 

modal energy use reductions, annualized cost, energy cost saving, net savings, net savings per 

unit of GHG emissions reductions, net savings per unit of energy use reduction, and simple 

pay-back periods for these four selected best practices. 

Three of these four best practices produce net cost savings. These savings are the net 

result of substantial costs offset by substantial savings based on reduced energy usage. For one 

of the best practices, B20 biodiesel, the net savings are negative, indicating that these practices 

do not pay for themselves. It is because that B20 biodiesel fuel cost is higher than that for 

petroleum diesel (based on current typical experience) and thus there is a net increase in total 

costs. When net cost savings are normalized based on the GHG emissions reductions, 

combined diesel powered heating and start/stop system, battery-diesel hybrid switching 

locomotive, and plug-in units appear to be more cost-effective, whereas the use of B20 biodiesel 

appears to be less cost effective. However, combined diesel powered heating and start/stop 

system, battery-diesel hybrid switching locomotive, and biodiesel practices have the potential to 

achieve large magnitudes of GHG emissions reductions, but plug-in units could only contribute 

small magnitude of GHG emissions reductions because this practice can be only used in 

switching yard; therefore, this restriction limits its potential for GHG emissions reductions and 

energy reduction. 
59

Table 5- 2. Summary Table for the Comparison of the Quantitative Cost Results for 

Selected Best Practices for the Rail Modea 

Best Practice Number 2-1 2-2 2-3 2-6 

Name 

Combined Diesel 

Powered Heating System 

and Auto Engine 

Start/stop System 

Battery Diesel 

Hybrid Switching 

Locomotive 

Plug-In 

Unit 

B20 

Biodiesel 

Subgroup Anti-idling Anti-idling Anti-idling Alternative 

Fuel 

Responsible Parties 26, 27, 28, 35, 36, 37 26, 27 26, 27 23, 25, 26, 

28, 29 

Target Parties 11, 13 11 11 8, 10 

Target GHGs CO2 CO2 CO2 CO2

Strategy Types Technology Technology Technology Technology 

Developmental Status P C P N 

Modal GHG Emission 

Reduction 

(106

 ton CO2 eq./year) 

2.3 1.1 0.4 3.5 

Modal Energy Use Reduction 

(1012 BTU/year) 29 14 4 -42 

Annualized Costs 

($ 106/year) 140 180 91 380 

Annual Energy Cost Saving 

($ 106

/year) 530 260 230 0 

Net Saving ($ 106/year) 390 70 135 -380 

Net Saving per Unit of GHG 

Emissions Reductions 

($/ton CO2 eq.) 

167 65 364 -109 

Net Saving per Unit of 

Energy Use Reduction 

($/ton CO2 eq.) 

13.5 5.2 38 N/Ab

Simple Pay-back Period 

(years) 2.1 5.5 0.8 N/Ac

a

 These assessments are based on the assumptions that these best practices reach their potential 

maximum market shares in 2025. Cost results are presented only for those best practices for which 

adequate data were available. 

b

 This practice has no energy use reduction due to an increase in energy use, and it has no net saving due 

to high annualized cost and no energy cost saving. c

 There is no pay-back period for this best practice because there is no net saving. 
60

6.0. BEST PRACTICES FOR THE AIR MODE 

This chapter identifies and characterizes 10 potential best practices applicable to the air 

mode. These best practices are divided into 5 subgroups, including: aerodynamic drag 

reduction; air traffic management; weight reduction; ground support equipment improvement; 

and engine improvement. Details regarding these best practices are in Appendix C. 

This chapter provides an overview of several potential best practices for greenhouse gas 

emissions reductions for the aviation freight transportation mode. However, this work is merely 

illustrative of possible best practices. Potential best practices were identified based on literature 

review. However, there may be other potential best practices that are not addressed here. 

Furthermore, in some cases, although potential best practices might be identified in the literature 

qualitatively, there is a lack of quantitative estimates of the possible impact of these potential 

best practices on emissions reductions. In general, there is a lack of reliable cost data for 

aviation potential best practices. Therefore, the information provided here is considered to be 

an initial but limited starting point for further identification and characterization of aviation 

freight potential best practices. 

For aviation freight, there are many means by which to achieve reductions in fuel use and 

greenhouse gas emissions. These include potential changes in operations, aircraft design, 

engine design, fuels, and ground support, among others. For example, operations includes air 

traffic control, standard procedures for operation and movement of the aircraft on the ground, 

take-off and landing procedures, and so on. For example, take-off procedures with derated or 

reduced thrust are estimated to reduce emissions of criteria air pollutants, such as NOx, but may 

slightly increase the fuel consumption and GHG emissions.80 In some cases, the potential best 

practices may be many years from realization, and thus there is limited information upon which 

to base an assessment at this time (e.g., IPCC, 1999).81 

In addition to technical options for potential best practices, there are policy options for 

strategies that potentially could reduce energy use and greenhouse gas emissions. For example, 

policy options for reducing the growth of emissions from the air mode may include more 

stringent regulations, reductions of subsidies and incentives that currently lead to negative 

environmental impacts, market-based mechanisms (e.g., carbon tax and emissions trading), 

voluntary agreements, research programs, and inter-modal shifts. However, the efficacy and 

costs of such approaches are not adequately characterized for purposes of analysis here.81 
61

6.1 Aerodynamic Drag Reduction 

Most of the fuel consumed by airplanes is needed to overcome aerodynamic drag, since 

they fly at very high speed. Reduction of aerodynamic drag can significantly improve the fuel 

efficiency of airplanes.82 Aerodynamic drag can be reduced by installing add-on devices, such 

as film surface grooves, hybrid laminar flow technology, blended winglets, and spiroid tips. 

6.1.1 Best Practice 3-1: Surface Grooves 

Skin friction drag, also referred to as viscous drag, is caused by the contact of the air flow 

against the surface of the aircraft, and is impacted by the viscosity property of air. An approach 

that is undergoing testing is the use of an adhesive-backed film with micro-grooves that is placed 

on the exterior surfaces of the wings and the fuselage of the airplane. The series of microscopic 

grooves produces a drag-reducing surface. The reduction in skin friction drag results in a 

decrease in fuel use. Based upon results of wind tunnel and flight tests, this device is estimated 

to reduce total aerodynamic drag by up to 1.6%.82 The estimated potential reduction in modal 

GHG emissions is 1.6%. The disadvantage of this practice is that the lifetime of the film with 

micro-grooves is only 2 to 3 years. Thus, research is needed to improve the durability of the 

materials for the film. 

6.1.2 Best Practice 3-2: Hybrid Laminar Flow Technology 

Aerodynamic drag associated with skin friction can be reduced if turbulent air flow can 

be replaced by laminar airflow over the aircraft skin surface. Laminar flow is a smooth air flow 

moving across an airfoil without turbulence, but it is usually destroyed by turbulence induced 

because of interactions with wing surfaces, leading to skin friction. Furthermore, 

contamination on the aircraft surface, such as the accumulation of ice, insects or other debris, 

degrades laminar flow. A newly developed concept, hybrid laminar flow technology, integrates 

both passive and active approaches to maintain laminar flow. A passive device requires no 

energy for its operation. An active device requires a source of energy for its operation. 

Passive anti-contamination devices are used to prevent or minimize contamination. 

Examples of such devices include: design of the wing surface geometry to have favorable 

pressure gradient; insect shields, removable coverings, continuous liquid dischargers and 

deflectors to prevent insect contamination; and anti-freeze agent dischargers and heat application 

techniques to avoid ice accumulation.83 An example of a passive anti-contamination device is a 

Krueger flap. This flap has hinged droop surfaces on the leading edge of the wings that can be 

used for ice and insect-contamination prevention.84 

An active approach, a suction system, is comprised of a multi-layer panel on a wing 
62

surface. The multi-layer panel includes a thin outer layer with fine pores and a thicker inner 

layer. The space between these two layers is divided into chambers. Air is sucked through the 

pores on the outer layer, then is vented through ducts out of the aircraft.84 The ducts are located 

to avoid negative impact to the aerodynamic performance of the aircraft. The air suction 

process can reduce air flow turbulence to maintain laminar flow on the surface of a wing.82,84-85 

Taking into account the power used for suction, the combination of these passive and 

active approaches can reduce fuel use by 6% to 10%.82 The estimated potential reduction in 

modal GHG emissions is 6.0%. 

6.1.3 Best Practice 3-3: Blended Winglet 

Lift-induced drag is due to the tip vortices produced by a lifting wing. A blended 

winglet is a commercially available wing-tip device that can reduce lift-induced drag. A 

winglet is an extension mounted at the tip of a wing. A blended winglet combines part of the 

wing tip with the winglet using a smooth blended shape that can decrease the tip vortex intensity. 

From the results of field tests, the weakened vortex intensity caused by a blended winglet 

decreases lift-induced drag by 4% and reduces energy use by 2%.82 The estimated potential 

reduction in modal GHG emissions and energy use are both 2.0%. This practice increases the 

surface area of the wing of the aircraft, which could increase the viscous drag. The effect of 

additional viscous drag associated with the surface area increase is accounted for in the estimate 

given here. 

 

6.1.4 Best Practice 3-4: Spiroid Tip 

An alternative type of wing-tip device is a spiroid tip. This device has been pilot tested 

and, like blended winglets, is intended to reduce lift-induced drag. A spiroid tip is a spiral loop 

formed by joining vertical and horizontal winglets. This technique can decrease tip vortex 

intensity and, therefore, reduce lift-induced drag. From the results of model simulations, 

spiroid tip can reduced lift-induced drag by 3.3% and reduce energy use by 1.7%.82 The 

estimated potential reduction in modal GHG emissions and energy use are both 1.7%. This 

practice increases the surface area of the wing of the aircraft, which could increase the viscous 

drag. The effect of additional viscous drag associated with the surface area increase is 

accounted for in the estimate given here. 

6.2 Air Traffic Management ― Best Practice 3-5 

Optimized air traffic management systems are in the development stage. Compared to 

the current air traffic control system, there are opportunities to reduce congestion and improve 
63

aircraft routing in order to reduce fuel consumption. Advanced air traffic management systems 

can optimize air traffic flow, provide efficient route options, and increase situation awareness. 

These systems are expected to reduce aviation fuel use by 6 to 12 percent, depending on the 

implementation of international arrangements.81 The estimated potential reduction in modal 

GHG emissions and energy use are both 6.0%. 

Air traffic management improvement is a potential best practice. An example of such 

an approach is the implementation of Communication, Navigation, Surveillance/Air Traffic 

Management (CNS/ATM). The concept of CNS/ATM, formerly known as the future air 

navigation systems (FANS) concept, was created by the International Civil Aviation Organization 

(ICAO), in cooperation with the aviation civil community. This concept aims at improving 

traffic control and airline management by applying new technologies, such as satellites and 

advanced computers, data links, and advanced flight avionics, to enhance capabilities of 

satellite-based navigation and digital data link communication systems. With the enhanced 

capabilities, the combination of new CNS technologies and the next generation of ATM systems 

will reduce fuel use, emissions, noise, and airspace congestion.86 

In the US, the Federal inter-agency Joint Planning and Development Office (JPDO) has 

been established based on “Vision-100” legislation (Public Law 108-176) signed by the President 

in December 2003. JPDO is designing an advanced air transportation system, the Next 

Generation Air Transportation System (NextGen), which is intended for deployment by 2025.87 

Many technologies are being developed for NextGen, such as the Automatic Dependent 

Surveillance Broadcast (ADS-B) and the System Wide Information Management (SWIM).88 

ADS-B is a satellite-based surveillance and control systems intended to replace 

traditional ground-based surveillance and control systems. ADS-B includes aircraft on-board 

navigation systems and data-links. The former collects aircraft position and velocity data. 

The later automatically transmits data to air traffic control radar systems. The application of 

ADS-B will enhance operational efficiency and reduce fuel use by reducing visibility restrictions 

because pilots will be able to see what air traffic controllers see.86,88 

SWIM is a networking-based initiative that will link needed information, such as position, 

weather, and restricted airspace notices, and will deliver high-quality, timely data to users 

involved in the NextGen system. SWIM will reduce the number and types of interfaces and 

systems, thereby enhancing operational efficiency and expanding system capacity.88 

The implementation of CNS/ATM or the NextGen systems will provide new 

capabilities.88,89 Three examples of new capabilities are: 

(1) Reduced Vertical Separation Minimum (RVSM): 

The RVSM is a procedure that allows air traffic controllers and pilots to reduce 

the standard required vertical separation from 2,000 feet to 1,000 feet between aircraft 
64

flying at altitudes between 29,000 and 41,000 feet. The RVSM will enhance aircraft 

operating efficiency by increasing the number of more fuel and time efficient flight 

altitudes.90,91 

(2) Continuous Descent Approach (CDA): 

The conventional “dive-and-drive” aircraft arrival and approach procedures 

requires the use of high thrust, the deployment of flaps and landing gear to slow the 

aircraft while it levels off at different stages, which results in additional fuel consumption, 

noise and pollution. The CDA is a procedure that optimizes the aircraft landing. CDA 

involves a continuous descent of the aircraft on a constant slope without need to deploy 

flaps and landing gear. CDA flight tests in 2004 demonstrated reductions in fuel 

consumption of 900 lb to 1,500 lb compared to a conventional approach.88,92 

(3) Oceanic Trajectory-Based Operations: 

Aircraft currently use designated routes to fly over oceanic airspace. 

Trajectory-based operations would enable pilots to tailor their individual flight paths 

based on four-dimensional trajectories, which include altitude, longitude, latitude, and 

time, of other aircraft. The advantages of trajectory-based operations are avoided 

congestion, more efficient use of airspace, and reduction in fuel use.88 

 

6.3 Weight Reduction 

Reductions in the weight of aircraft through the use of light-weight materials and weight 

reduction of non-essential components could lead to significant reductions in fuel use.81 

6.3.1 Best Practice 3-6: Airframe Weight Reduction 

The weight of an airframe is approximately 50% of an aircraft’s gross weight. Adoption 

of advanced lighter and stronger materials in the structural components of the airframe, such as 

aluminum alloy, titanium alloy, and composite materials for non-load-bearing structures, can 

reduce airframe weight, thereby leading to a reduction in fuel use.81 The International Civil 

Aviation Organization (ICAO) estimated that adoption of such materials can reduce structural 

weight by 4%.93 The estimated potential reduction in modal GHG emissions and energy use are 

both 2.0%. More research and development is needed to reach the projected structure weight 

reduction target. 

6.3.2 Best Practice 3-7: Non-Essential Weight Reduction 

Trimming non-essential weight from aircraft can reduce fuel use. Adjustments to the 

amount of fuel, water, and emergency equipment onboard with respect to anticipated 
65

requirements and a contingency allowance can reduce fuel use by no more than 1%.81 The 

estimated potential reduction in modal GHG emissions is 1.0%. 

6.4 Ground Support Equipment Improvement 

Ground support equipment can be designed and deployed to help reduce energy use 

on-board aircraft, or can be redesigned to be more fuel efficient. Potential best practices for 

ground support equipment include supplying energy for aircraft operation on the ground and 

substation of electric and hybrid delivery trucks for conventional trucks.81,94-97 

6.4.1 Best Practice 3-8: Ground-Based Equipment as an Alternative to 

Auxiliary Power Units 

Aircraft auxiliary power units (APUs) are engine-driven generators that supply electricity 

for use aboard the plane while at a cargo loading area. An alternative method for supplying 

electricity is to connect the aircraft to shore-based power or to use ground-based equipment to 

generate power for delivery to the aircraft. Such ground-based equipment has been pilot tested. 

Ground-based equipment can reduce APU fuel use significantly while the aircraft is at the gate.94 

The reported estimates of fuel use and GHG emissions reductions for this best practice are 

combined with those of Best Practice 3-9. The estimated combined reduction in modal fuel use 

and GHG emissions for Best Practices 3-8 and 3-9 are 2.9%.96-97 

6.4.2 Best Practice 3-9: Electric or Hybrid Heavy Duty Delivery Trucks 

Off-road electric or hybrid vehicles for supporting airport operations have been 

pilot-tested. Such vehicles can replace existing, older ground support equipment. An off-road 

electric powered delivery vehicle can operate for 100 miles after a single charge, carry 3,000 lbs 

of cargo, travel at a speed of up to 30 miles per hour, and climb grades up to 10%. These 

capabilities are suitable for ground equipment service. Other alternative ground support 

equipment propulsion systems can be based on LPG or gasoline powered hybrid vehicles.94-95 

As explained in Section 6.4.1, the reported estimates of fuel use and GHG emissions reductions 

for this best practice are combined with those of Best Practice 3-8. The estimated combined 

reduction in modal fuel use and GHG emissions for Best Practices 3-8 and 3-9 are 2.9%.96-97 

Reduction in cost is needed to expand the market penetration potential of this practice. 

6.5 Engine Improvement ― Best Practice 3-10: Improved Engine Overall Efficiency 

Current aircraft energy efficiency, the amount of energy used to transport one unit of 

payload over a distance, is about 10-13 MJ per ton-mile.98 Aircraft fuel consumption can be 
66

reduced based on improving engine efficiency. Engine efficiency can be improved through 

increasing fan bypass ratio, increasing pressure ratio of compressor and better mixing of fuel and 

air prior to combustion. 

A new jet engine with several advanced technologies is being developed and is scheduled 

to enter the market in 2008. One of the engine technologies features larger fan sizes to reach 

high engine bypass ratio by 9.5,99 which is higher than 5 to 9 bypass ratios of today’s most 

advanced engines.81 The increased fan weight caused by larger size is offset by a reduced 

number of fan blades and the use of composite materials. This engine is also equipped with a 

high-pressure compressor that produces a 23:1 pressure ratio. Engine efficiency can be 

improved further by better mixing of fuel and air, which leads to a more homogenous lean 

fuel/air mixture that burns more evenly, thereby reducing local pockets of incomplete 

combustion. Moreover, a fuel-efficient technology that runs the high-pressure turbine 

clockwise and the low-pressure turbine counterclockwise has been demonstrated in tests and is 

also included in the new engine design. Based on vendor information, this technology is 

estimated to reduce fuel use by 13.0%.99-100 The estimated potential reduction in modal GHG 

emissions and energy use are both 13.0%. 

6.6 Summary of Potential Best Practices for the Air Mode 

All 10 potential best practices, sorted by 5 subgroups, for the air mode are summarized in 

Table 6-1. They are in table format for the convenience of readers. 

6.7 Comparisons of the Modal GHG Emissions Reductions for the Best Practices 

Figure 6-1 illustrates the variability among the potential best practices with respect to 

estimated reductions in modal GHG emissions. 

The percentage reductions in modal GHG emissions range from 1.0 to 13.0 percent when 

comparing individual best practices. However, these percentage reductions cannot be summed 

to obtain a total emission reduction. Some best practices are mutually exclusive or have 

interactions with others. 

For all of the 10 identified best practices for the air mode, there is a lack of sufficient 

information to support quantitative assessments. For these strategies, qualitative assessments 

are summarized in simplified summary tables individually. If sufficient information becomes 

available in the future, best practices that are assessed here qualitatively could be reassessed 

quantitatively. 
67

Table 6- 1. List and Description of Potential Best Practices for the Air Mode 

Subgroup Type of 

Strategies Description

Technology 

3-1. Surface Grooves

Skin friction drag, also referred to as viscous drag, is caused by the contact 

of the air flow against the surface of the aircraft, and is impacted by the 

viscosity property of air. An approach that is undergoing testing is the use 

of an adhesive-backed film with micro-grooves, each a few thousandths of

an inch wide, that is placed on the exterior surfaces of the wings and the 

fuselage of the airplane. These grooves are called V-groove riblets. 

Riblets produce a drag-reducing surface. The reduction in skin friction 

drag results in a decrease in fuel use. Based upon results of wind tunnel 

and flight tests, this device is estimated to reduce total aerodynamic drag by 

up to 1.6%.82 The estimated potential reduction in modal GHG emissions 

and energy use are both 1.6%. One disadvantage of the riblet is that its

lifetime is only 2 to 3 years.82 

Aerodynamic 

Drag 

Reduction 

Technology 

3-2. Hybrid Laminar Flow Technology

Aerodynamic drag associated with skin friction can be reduced if turbulent 

air flow can be replaced by laminar airflow over the aircraft skin surface. 

Laminar flow is a smooth air flow moving across an airfoil without 

turbulence, but it is usually destroyed by turbulence induced because of 

interactions with wing surfaces, leading to skin friction. Furthermore, 

contamination on the aircraft surface, such as the accumulation of ice, 

insects or other debris, degrades laminar flow. A newly developed 

concept, hybrid laminar flow technology, integrates both passive and active 

approaches to maintain laminar flow. A passive device requires no energy 

for its operation. An active device requires a source of energy for its 

operation. 

Passive anti-contamination devices are used to prevent or minimize 

contamination. Examples of such devices include: design of the wing 

surface geometry to have favorable pressure gradient; insect shields, 

removable coverings, continuous liquid dischargers and deflectors to 

prevent insect contamination; and anti-freeze agent dischargers and heat 

application techniques to avoid ice accumulation.83 An example of a 

passive anti-contamination device is a Krueger flap. This flap has hinged 

droop surfaces on the leading edge of the wings that can be used for ice and 

insect-contamination prevention.84 

An active approach, a suction system, is comprised of a multi-layer panel 

on a wing surface. The multi-layer panel includes a thin outer layer with 

fine pores and a thicker inner layer. The space between these two layers is 

divided into chambers. Air is sucked through the pores on the outer layer, 

then is vented through ducts out of the aircraft.84 The ducts are located to 

avoid negative impact to the aerodynamic performance of the aircraft. 

The air suction process can reduce air flow turbulence to maintain laminar 

flow on the surface of a wing.82,84-85 

Taking into account that the power used for suction is approximately 1% of 

aircraft fuel use, the combination of these passive and active approaches 

can reduce fuel use by 6% to 10%.82 The estimated potential reduction in 

modal GHG emissions is 6.0%. 

Continued on next Page
68

Table 6-1. Continued 

Subgroup Type of 

Strategies Description

Technology 

3-3. Blended Winglet

Lift-induced drag is due to the tip vortices produced by a lifting wing. A 

blended winglet is a commercially available wing-tip device that can reduce 

lift-induced drag. A winglet is an extension mounted at the tip of a wing. 

A blended winglet combines part of the wing tip with the winglet using a 

smooth blended shape that can decrease the tip vortex intensity. From the 

results of field tests, the weakened vortex intensity caused by a blended 

winglet decreases lift-induced drag by 4% and reduces energy use by 

2%.82,101 This practice, however, increases surface area that increases the 

viscous drag.82 The estimated potential reduction in modal GHG 

emissions and energy use are both 2.0%. 

Aerodynamic 

Drag 

Reduction 

Technology 

3-4. Spiroid Tip

An alternative type of wing-tip device is a spiroid tip. This device has 

been pilot tested and, like blended winglets, is intended to reduce 

lift-induced drag. A spiroid tip is a spiral loop formed by joining vertical 

and horizontal winglets. This technique can decrease tip vortex intensity 

and, therefore, reduce lift-induced drag. From the results of model 

simulations, spiroid tip can reduced lift-induced drag by 3.3% and reduce 

energy use by 1.7% or more.82 This practice, however, increases surface 

area that increases the viscous drag.82 The estimated potential reduction in 

modal GHG emissions and energy use are both 1.7%. 

Air Traffic 

Management Operation 

3-5. Air Traffic Management Improvement

Air traffic management systems are designed for the guidance, separation, 

coordination, and control of aircraft movements. Today’s air traffic 

control systems have limitations which result in traffic congestion and 

inefficient routings. For example, aircraft operators in existing system 

need to follow established, inefficient airways. These limitations result 

in the increase of fuel use, air pollutants emissions, and GHG emissions. 

Optimized air traffic management systems are in the development stage. 

Compared to the current air traffic control system, there are opportunities 

to reduce congestion and improve aircraft routing in order to reduce fuel 

consumption. Advanced air traffic management systems can optimize 

air traffic flow, provide efficient route options, and increase situation 

awareness. These systems are expected to reduce aviation fuel use by 6 

to 12 percent, depending on the implementation of international 

arrangements.84 The estimated potential reduction in modal GHG 

emissions and energy use are both 6.0%. 

Continued on next Page 
69

Table 5-1. Continued 

Subgroup Type of 

Strategies Description

Technology 

3-6. Airframe Weight Reduction

The weight of an airframe is approximately 50% of an aircraft’s gross 

weight. Adoption of advanced lighter and stronger materials in the 

structural components non-load-bearing structures of the airframe, such as 

aluminum alloy, titanium alloy, and composite materials for, can reduce 

airframe weight, thereby leading to a reduction in fuel use. Some design 

technologies, such as high-fidelity finite element models (FEMs), can be 

used for strength analysis to understand safety load-factor margins and 

reduce structural weight.81 Historical trends demonstrated that airplane 

manufactures keep decreasing structural weight of airframes. For 

example, the Boeing 777, which is developed a decade ago, had an airframe 

with 10% composite structure by weight. The newly introduced Airbus 

380 has an airframe with 25% composite structure by weight. The Boeing 

787, scheduled for delivery beginning in 2008, will have an airframe with

50% composite structure by weight.102 The International Civil Aviation 

Organization (ICAO) estimated that adoption of such materials can reduce

structural weight by 4%.93 However, improved techniques for 

investigating the airframe with composite material are needed to avoid 

structure failure.102 The estimated potential reduction in modal GHG 

emissions and energy use are both 2.0%. 

Weight 

Reduction 

Operation 

3-7. Non-Essential Weight Reduction

Trimming non-essential weight from aircraft can reduce fuel use. 

Additional non-essential weight has several sources, such as extra aviation 

fuel, potable water and emergency equipments. Aviation fuel onboard is 

usually more than that required by the flight plan. Carrying extra fuel is 

because of several reasons, such as safety concern, fuel price difference

among two places, fuel availability at some remote sites, fuel quality 

concern at some locations, or insufficient time for refueling. Carrying 

extra potable water and emergency equipment also increase non-essential 

weight of aircrafts. Adjustments to the amount of fuel, water, and 

emergency equipment onboard with respect to anticipated requirements and 

a contingency allowance can reduce fuel use by no more than 1%.81 The 

estimated potential reduction in modal GHG emissions and energy use are 

both 1.0%. 

Ground 

Support 

Equipment 

Improvement 

Technology 

3-8. Ground-Based Equipment as Alternative to Auxiliary Power Units

Aircraft auxiliary power units are engine-driven generators that supply 

electricity for use aboard the plane while at a cargo loading area. An 

alternative is to connect the aircraft to shore-based power or to use 

ground-based equipment to generate power for delivery to the aircraft. 

Such equipment has been pilot tested. Ground-based equipment can 

reduce APU fuel use significantly while the aircraft is at the gate.81 The 

reported estimates of fuel use and GHG emissions reductions for this best 

practice are combined with those of Best Practice 3-9. The estimated 

combined reduction in modal fuel use and GHG emissions for Best 

Practices 3-8 and 3-9 are 2.9%.96-97 

Continued on next Page 
70

Table 5-1. Continued 

Subgroup Type of 

Strategies Description

Ground 

Support 

Equipment 

Improvement 

Technology 

3-9. Electric or Hybrid Heavy Duty Delivery Trucks

Off-road electric or hybrid vehicles for supporting airport operations have 

been pilot-tested. Such vehicles can replace existing, older ground 

support equipment. An off-road electric powered delivery vehicle,

equipped with a 320 volt AC drive train, can operate for 100 miles after a 

single charge, carry 3,000 lbs of cargo, travel at a speed of up to 30 miles 

per hour, and climb grades up to 10%. These capabilities are suitable for 

ground equipment service. Other alternative ground support equipment 

propulsion systems can be based on LPG or gasoline powered hybrid 

vehicles.94-95 As explained in Section 6.4.1, the reported estimates of fuel 

use and GHG emissions reductions for this best practice are combined with 

those of Best Practice 3-8. The estimated combined reduction in modal 

fuel use and GHG emissions for Best Practices 3-8 and 3-9 are 2.9%.96-97 

Engine 

Improvement Technology 

3-10. Improved Engine Overall Efficiency

Current aircraft energy efficiency, the amount of energy used to transport 

one unit of payload over a distance, is about 10-13 MJ per ton-mile.98

Aircraft fuel consumption can be reduced based on improving engine 

efficiency. Engine efficiency can be improved through increasing fan 

bypass ratio, increasing pressure ratio of compressor and better mixing of

fuel and air prior to combustion. 

A new jet engine with several advanced technologies is being developed 

and is scheduled to enter the market in 2008. One of the engine 

technologies features larger fan sizes to reach high engine bypass ratio by 

9.5,99 which is higher than 5 to 9 bypass ratios of today’s most advanced 

engines.81 The increased fan weight caused by larger size is offset by a 

reduced number of fan blades and the use of composite materials. This 

engine is also equipped with a high-pressure compressor that produces a 

23:1 pressure ratio. Engine efficiency can be improved further by better 

mixing of fuel and air, which leads to a more homogenous lean fuel/air 

mixture that burns more evenly, thereby reducing local pockets of

incomplete combustion. Moreover, a fuel-efficient technology that runs 

the high-pressure turbine clockwise and the low-pressure turbine 

counterclockwise has been demonstrated in tests and is also included in the 

new engine design. Based on vendor information, this technology is 

estimated to reduce fuel use by 13.0%.99-100 The estimated potential 

reduction in modal GHG emissions and energy use are both 13.0%. 
71

0

2

4

6

8

10

12

14

3-1 3-2 3-3 3-4 3-5 3-6 3-7 3-8 3-9 3-10

Best Practice Number for the Air Mode 

*The reduction in modal GHG emissions for Best Practice 3-9 represents the estimated combined 

reduction in modal GHG emissions for Best Practices 3-8 and 3-9 

Figure 6- 1. Reductions in Modal GHG Emissions for the Best Practices for the Air Mode Modal GHG Emissions Reductions (%) 

* *
72

7.0 BEST PRACTICES FOR THE WATER MODE 

This chapter identifies and characterizes five potential best practices applicable to the 

water mode. These best practices are divided into three subgroups, including: 

• improved propeller system; 

• anti-idling; and 

• alternative fuel. 

Additional details regarding all of these best practices are in Appendix D. For one of 

these best practices, sufficient data were available to quantify costs. 

7.1 Propeller System Improvement 

A ship uses a propeller to convert ship engine power into thrust for propulsion of the ship. 

As ships move through the water, they produce energy-consuming turbulent vortices depending 

on speed, ship hull geometry, and propeller design. A number of modified propeller systems 

have been introduced in order to improve the overall energy efficiency of ship propulsion. 

These systems are designed based on attempts to recover energy from turbulent vortices in the 

water, or to prevent the formation of such vortices. This, in turn, leads to reduction in ship fuel 

use and exhaust CO2 emissions.103-105 

7.1.1 Best Practice 4-1: Off-Center Propeller 

The movement of the ship through water produces vortices in the water. The formation 

of such vortices requires energy. Thus, a portion of the energy expended to move the ship is 

transferred to the creation of such vortices. For example, vortices that are formed along the rear 

part of the ship and that flow into the wake are the result of turbulence. Such vortices are 

referred to as “bilge vortices” and they effectively increase the resistance of water movement 

around the ship hull. An off-center propeller is a commercially available device that attempts to 

capture some of the flow and energy contained within the bilge vortices to enhance propulsion 

efficiency. An off-center propeller is part of a system that includes the rudder and properly 

shaft located away from the longitudinal centerline of the ship. From the result of tank tests, an 

off-center propeller was estimated to reduce ship propulsion energy use by 3% or more. This 

practice can be implemented for new ships but is difficult or impractical to retrofit to existing 

ships. This practice was combined with a refined hull shape and other energy-saving measures 

in a large ore carrier, which lead to a total estimated reduction in energy use of 14%.103 The 

estimated potential reduction in modal GHG emissions is 1.5%, assuming that the off-center 
73

propeller alone contributed only partially to the total estimated reduction in energy use of the ore 

carrier, as well as implementation on only a portion of freight ships. This practice can be 

implemented for new ships but it is difficult or impractical to retrofit to existing ships. 

7.1.2 Best Practice 4-2: Propeller Boss Cap with Fins (PBCF) 

Turbulent vortices are generated by propeller rotation. The formation of vortices 

requires energy. Thus, energy that could be used for propulsion is diverted to the formation of 

vortices, which reduces the overall energy efficiency of the propulsion system. A method for 

reducing the formation of vortices associated with the propeller ration is the use of a propeller 

boss cap with fins (PBCF).104 PBCF is commercially available, and approximately 1,000 

ships have adopted this practice as of 2006.106 The PBCF includes small fins installed behind 

the propeller and that rotates in the same direction as the propeller. The purpose of these fins is 

to avoid the formation of vortices. From the results of field tests, this device appears to be able 

to reduce propulsion fuel use by 4 to 5 percent.104 The estimated potential reduction in modal 

GHG emissions is 2.0%, assuming either less effectiveness in practice or implementation on only 

a portion of freight ships. 

7.1.3 Best Practice 4-3: Auxiliary Free-Rotating Propulsion Device behind 

the Main Propeller 

As noted in the previous section, propeller rotation results in the formation of 

energy-consuming turbulent vortices unless mitigating measures are implemented. An 

alternative to PBCF is a grim vane wheel (GVW). GVW is a commercially available device, 

and approximately 59 ships had adopted this practice as of 2000.107 It is an auxiliary 

free-rotating propulsion device that has vanes with larger diameter than that of propeller and is 

located immediately behind the main propeller. The rotation of GVW modifies the accelerated 

flow of water that is leaving the propeller, recovers a portion of the energy embodied in the 

accelerated flow of water, and in so doing provides extra propulsion. A newly designed GVW 

system can be mounted on the rudder horn instead of propeller shaft, which may improve 

reliability. From the results of field tests, GVW techniques may reduce propulsion fuel use by 

6% or more.105107 Taking into account that not all ships will adopt this technique, the estimated 

potential reduction in modal GHG emissions is 3.0%. 

7.2 Anti-Idling ― Best Practice 4-4: Shoreside Power for Marine Vessels at Ports 

Shoreside power is being tested as ship anti-idling system that can avoid the need for 

running the ship auxiliary engine continuously while a ship is docked at a port. Shoreside 
74

power is a system that connects the ship to an external electrical power source, thereby avoiding 

the need for use of the auxiliary engine. Thus, this system can reduce ship fuel use and GHG 

emissions. Taking into account reduced shipboard energy use and emissions, and increased 

shoreside energy use and emissions to produce electricity, shoreside power can reduce overall 

GHG emissions compared to an auxiliary engine by 13%.108-109 However, the fuel use for the 

auxiliary engine is only a small fraction of total marine fuel use. Assuming that only a fraction 

of all ships adopts this technique and that ship auxiliary engines only use a small fraction of 

marine fuel, the estimated potential reduction in modal GHG emissions is 0.2%. 

7.3 Alternative Fuel ―Best Practice 4-5: B20 Biodiesel Fuel for Ships 

Large ocean-going ships usually have multiple engines, including main engines and 

auxiliary engines. Since 1980, all marine engines have been diesel-powered engines. Main 

marine engines usually burn residual fuel or blends of residual and distillate fuels.110 Auxiliary 

engines usually burn marine gas oil, a high sulfur diesel fuel that is usually the fuel for small and 

medium sized marine engines. Thus, ocean-going ships often carry both residual fuel oil and 

marine gas oil.111 For marine fuel consumption, residual fuel oil for freight ships is about 60% 

of total marine fuel use. Distillate fuel for freight ships is about 11% of total marine fuel use. 

Distillate fuel for other ships (such as passenger ships, fish ships, military ships) accounts for 

other 29% of marine fuel use.112 

B20 biodiesel, which is described in Section 4.11.2, is a potential alternative fuel for 

marine gas oil powered diesel engines.113 Based on a life cycle analysis, the CO2 emissions are 

estimated to decrease by 0.0069 tons CO2 eq. per 106 BTU for B20 biodiesel compared to 

land-use diesel fuel. Land-use diesel fuel and marine gas oil are both distillate fuels but differ 

in that land-use diesel fuel has a much lower sulfur level than the marine gas oil. Sulfur 

concentrations in distillate fuels can be reduced by a refining process, hydro-treating, that 

consumes energy and emits CO2.

111 Since marine gas oil is high sulfur diesel fuel and removal 

of sulfur emits more GHG, the production of marine gas oil emits less GHG than the production 

of land-use diesel fuel based on life cycle inventories. The difference of life cycle GHG 

emission analysis results between B20 biodiesel and marine gas oil should be lower than the 

difference between B20 biodiesel and land-use diesel fuel. Thus, the latter provides a useful 

upper bound of the former. Taking into account that only a fraction of marine fuel is marine gas 

oil, the estimated potential reductions in modal GHG emissions are 1.2%.13,63-64,112,114-115 The 

estimated potential modal energy use increases by 1.3%.61 
75

7.4 Summary of Potential Best Practices for the Water Mode 

All five potential best practices, sorted by three subgroups, for the water mode are 

summarized in Table 7-1. They are in table format for the convenience of readers. 

7.6 Comparisons of the Modal GHG Emissions Reductions for the Best Practices 

Figure 7-1 illustrates the variability among the potential best practices with respect to 

estimated reductions in modal GHG emissions. 

These percentage reductions in modal GHG emissions range from 0.2 to 3.0 percent 

when comparing individual best practices. However, these percentage reductions cannot be 

summed to obtain a total GHG emission reduction. Some best practices are mutually exclusive 

with others, as described later in Chapter 9. 

7.7 Quantitative Cost Results for the Water Mode 

Quantitative cost results for the best practices for which sufficient information was 

available to perform such assessments are summarized in standardized reporting tables, which 

are given in Appendix D. In contrast, assessment results for the best practices which have a 

lack of sufficient information from which to quantify costs are summarized in simplified 

summary tables individually, which are also given in Appendix D. To date, there is sufficient 

information for one best practice upon which to make quantitative assessments. The other four 

best practices are assessed qualitatively. 

The best practice assessed quantitatively is B20 biodiesel for ships. Table 7-2 

summarizes the quantitative assessment results of modal GHG emissions reductions, modal 

energy use reductions, annualized cost, energy cost saving, net savings, net savings per unit of 

GHG emissions reductions, net savings per unit of energy use reduction, and simple pay-back 

periods for this selected best practice. 

For B20 biodiesel, the net savings are negative. B20 biodiesel fuel cost is higher than 

that for marine gas oil, and thus there is a net increase in total costs. 

The use of B20 has the potential to achieve a larger magnitude of total GHG emissions 

reductions. 
76

Table 7- 1. List and Description of Potential Best Practices for the Water Mode 

Subgroup Type of 

Strategies Description 

Propeller 

System 

Improvement 

Technology 

4-1. Off-Center Propeller

The movement of the ship through water produces vortices in the water. 

The formation of such vortices requires energy. Thus, a portion of the 

energy expended to move the ship is transferred to the creation of such 

vortices. For example, vortices that are formed along the rear part of 

the ship and that flow into the wake are the result of turbulence. Such 

vortices are referred to as “bilge vortices” and they effectively increase 

the resistance of water movement around the ship hull. An off-center 

propeller is a commercially available device that attempts to capture 

some of the flow and energy contained within the bilge vortices to 

enhance propulsion efficiency. An off-center propeller is part of a 

system that includes the rudder and properly shaft located away from 

the longitudinal centerline of the ship. For a ship with clockwise 

rotating propeller, the propeller is moved to starboard of the ship. For 

a ship with anti-clockwise rotating propeller, the propeller is moved to 

port of the ship. From the result of tank tests, an off-center propeller 

was estimated to reduce ship propulsion energy use by 3% or more. 

This practice can be implemented for new ships but is difficult or 

impractical to retrofit to existing ships. This practice was combined 

with a refined hull shape and other energy-saving measures in a large 

ore carrier, which lead to a total estimated reduction in energy use of 

14%.103 The estimated potential reduction in modal GHG emissions is 

1.5%, assuming that the off-center propeller alone contributed only 

partially to the total estimated reduction in energy use of the ore carrier, 

as well as implementation on only a portion of freight ships. 

Continued on next Page
77

Table 7-1. Continued 

Subgroup Type of 

Strategies Description 

Propeller 

System 

Improvement 

Technology 

4-2. Propeller Boss Cap with Fins

Turbulent vortices are generated by propeller rotation. The formation 

of vortices requires energy. Thus, energy that could be used for 

propulsion is diverted to the formation of vortices, which reduces the 

overall energy efficiency of the propulsion system. A ship propeller 

generates hub vortices behind it during operation. Water very close to 

the hub (e.g., 3 mm) flows along the direction of propeller rotation, but

water that has a small distance from the hub (e.g., 10 mm) flows in the 

opposite direction. These conflicting flows produce hub vortices that 

consume more energy. A method for reducing the formation of hub 

vortices associated with the propeller ration is the use of a propeller 

boss cap with fins (PBCF).104 PBCF is commercially available, and 

approximately 1,000 ships have adopted this practice as of 2006.106

The PBCF includes small fins that the number of fins is as the same as 

that of propeller blades. It is installed behind the propeller and that 

rotates in the same direction as the propeller. The purpose of these 

fins is to block water in hub vortices, move water along the direction of

propeller rotation, and produce a straight slip stream behind the 

propeller. From the results of field tests, this device appears to be able 

to reduce propulsion fuel use by 4 to 5 percent.104 The estimated 

potential reduction in modal GHG emissions is 2.0%, assuming either 

less effectiveness in practice or implementation on only a portion of

freight ships. The estimated capital cost of PBCF ranges from 

$20,000 for 735 kW engine to $146,000 for 22,050 kW engine, which 

can be recovered within two years by fuel cost savings. 

Continued on next Page
78

Table 7-1. Continued 

Subgroup Type of 

Strategies Description 

Propeller 

System 

Improvement 

Technology 

4-3. Auxiliary Free-Rotating Propulsion Device behind the Main 

Propeller 

As noted in the previous section, propeller rotation results in the 

formation of energy-consuming turbulent vortices unless mitigating 

measures are implemented. Ship propeller produces accelerated flow 

in the propeller wake that consumes energy. An alternative to PBCF 

is a grim vane wheel (GVW). GVW is a commercially available 

device that transfers accelerated flow in the wake into extra propulsion 

and increases fuel efficiency. Approximately 59 ships had adopted 

this practice as of 2000.107 It is an auxiliary free-rotating propulsion 

device that has vanes with larger diameter than that of propeller and is 

located immediately behind the main propeller. The rotation of GVW 

modifies the accelerated flow of water that is leaving the propeller, 

recovers a portion of the energy embodied in the accelerated flow of 

water, and in so doing provides extra propulsion. Older designs of 

GVW are mounted on the propeller shaft, but can have problems with 

mechanical failure. A newly designed GVW system can be mounted 

on the rudder horn instead of propeller shaft, which may improve 

reliability.105 From the results of field tests, GVW techniques may 

reduce propulsion fuel use by 6% or more.107 Taking into account that 

not all ships will adopt this technique, the estimated potential reduction 

in modal GHG emissions is 3.0%. The estimated capital cost of 

new-designed GVW is approximately $1.2 million dollars, which can 

be recovered in about three years based on fuel cost savings. 

Anti-Idling Technology 

4-4. Shoreside Power for Marine Vessels at Ports

Shoreside power is being tested as ship anti-idling system that can 

avoid the need for running the ship auxiliary engine while a ship is 

docked at a port. A docked ship usually runs its on-board auxiliary

engine continuously, which consumes energy and emits criteria air 

pollutants and GHGs at the port. Shoreside power at the port allows 

for shut down of the auxiliary engine and reduces fuel use and 

emissions. From the result of a report for European Commission, CO2

emitted from the ship auxiliary engine ranges from 690 to 720 

g/kWh,109 Average CO2 emissions from electricity production in the 

US are approximately 615 g/kWh.108 Taking into account reduced 

shipboard energy use and emissions, and increased shoreside energy 

use and emissions to produce electricity, this system reduces overall 

GHG emissions compared to auxiliary engine by approximately 13%.

European Commission report estimates that 60% of marine vessels are 

suitable for use of shore-side electricity.109 Taking into account that 

only a fraction of all ships adopts this technique and the ship auxiliary 

engines only use a small fraction of marine fuel, the estimated potential 

reduction in modal GHG emissions is 0.2%. The installation of

shoreside power for marine vessels at ports is likely to be phased-in 

over 5 to 10 years.116 

Continued on next Page 
79

Table 7-1. Continued 

Subgroup Type of 

Strategies Description 

Alternative 

Fuel Technology 

4-5. B20 Biodiesel Fuel for Ships

Large ocean-going ships usually have multiple engines, including main 

engines and auxiliary engines. Since 1980, all marine engines have 

been diesel-powered engines. Main marine engines usually burn 

residual fuel or blends of residual and distillate fuels.110 Auxiliary 

engines usually burn marine gas oil, a high sulfur diesel fuel that is 

usually the fuel for small and medium sized marine engines. Thus, 

ocean-going ships often carry both residual fuel oil and marine gas 

oil.111 For marine fuel consumption, residual fuel oil for freight ships 

is about 60% of total marine fuel use. Marine gas oil for freight ships 

is about 11% of total marine fuel use. Marine gas oil for other ships 

(such as passenger ships, fish ships, military ships) accounts for other 

29% of marine fuel use. Thus, marine gas oil accounts for 15% of 

marine fuel for freight ships.112 

B20 biodiesel, which is described in Section 4.11.2, is a potential 

alternative fuel for marine gas oil powered diesel engines.113 Based on 

a life cycle analysis, the CO2 emissions are estimated to decrease by 

0.0069 tons CO2 eq. per 106

 BTU for B20 biodiesel compared to 

land-use diesel fuel. Land-use diesel fuel and marine gas oil belong to 

distillate fuel except that the land-use diesel fuel has a much lower 

sulfur level than the marine gas oil. Sulfur concentrations in distillate 

fuels can be reduced by a refining process, hydro-treating, that 

consumes energy and emits CO2.

111 Since marine gas oil is high sulfur 

diesel fuel and removal of sulfur emits more GHG, the production of

marine gas oil emits less GHG than the production of land-use diesel 

fuel based on life cycle inventories. The difference of life cycle GHG 

emission analysis results between B20 biodiesel and marine gas oil 

should be lower than the difference between B20 biodiesel and land-use 

diesel fuel. Thus, the latter provides a useful upper bound of the 

former. Taking into account that only a fraction of marine fuel is 

marine gas oil, the estimated potential reductions in modal GHG 

emissions are 1.2%.13,63-64,114-115 The estimated potential modal energy 

use increases by 1.3%.61 
80

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4-1 4-2 4-3 4-4 4-5

Best Practice Number for the Water Mode 

Figure 7- 1. Reductions in Modal GHG Emissions for the Best Practices for the Water 

Mode 

Modal GHG Emissions Reductions (%) 
81

Table 7- 2. Summary Table for the Comparison of the Quantitative Cost Results for A 

Selected Best Practices for the Water Modea

 

Best Practice Number 4-5 

Name B20 Biodiesel 

Subgroup Alternative Fuel 

Responsible Parties 58, 61, 

Target Parties 23, 25 

Target GHGs CO2

Strategy Types Technology 

Developmental Status N 

Modal GHG Emissions Reductions 

(106

 ton CO2 eq./year) 1.5 

Modal Energy Use Reduction (1012

BTU/year) -18 

Annualized Costs 

($ 106/year) 180 

Annual Energy Cost Saving ($ 106/year) 0 

Net Saving ($ 106/year) -180 

Net Saving per Unit of GHG Emissions 

Reductions 

 ($/ton CO2 eq.) 

-120 

Net Saving per Unit of Energy Use 

Reduction 

 ($/ton CO2 eq.) 

N/Ab

Simple Pay-back Period (years) N/Ac

a

 These assessments are based on the assumptions that these best practices reach their potential 

maximum market shares in 2025. Cost results are presented only for this best practice for which 

adequate data were available. 

b

 This practice has no energy use reduction due to an increase in energy use, and it has no net saving due 

to high annualized cost and no energy cost saving. c

 There is no pay-back period for this best practice because there is no net saving. 
82

8.0 BEST PRACTICES FOR THE PIPELINE MODE 

This chapter identifies and characterizes 5 potential best practices applicable to the 

pipeline mode. The pipeline mode best practices focus on techniques or strategies applicable to 

natural gas pipelines. The main source of GHG emissions from these pipelines is leakage of 

natural gas, which is comprised mostly of methane. These best practices are divided into 3 

subgroups, including: 

• Improved process control devices; 

• connecting method; and 

• maintenance. 

Additional details regarding all of these best practices are in Appendix E. For three of 

these best practices, sufficient data were available to quantify costs. 

8.1 Process Control Device Improvement 

Natural gas pneumatic controls are used for pipeline operations. These controls are a 

source of methane leakage. Conversion of these controls to compressed instrument air systems 

or replacement of high-bleed with low-bleed devices, can reduce methane emissions 

significantly.117-119 

8.1.1 Best Practice 5-1: Convert Natural Gas Pneumatic Controls to 

Instrument Air 

Pneumatic control systems for pipelines are currently operated using pressurized natural 

gas. However, pneumatic controls based on compressed air could be used instead. Since 

natural gas is continuously bled from the current control devices, they are one of the largest 

methane emissions sources in the natural gas industry.1,117 Conversion of pneumatic control 

systems from natural gas to compressed air would reduce methane emissions.117 Taking into 

account the electricity energy needed for powering the compressed instrument air powered 

systems, the estimated potential reductions in modal GHG emissions and energy use are 0.5% 

and 0.1%, respectively. Since this practice needs electricity for its operation, it can be applied 

only in locations near electricity grids or by installing engine-generator sets at remote sites. 

The estimates given here are based on use of electricity from the grid, not from an 

engine-generator set. 
83

8.1.2 Best Practice 5-2: Replace High-Bleed Natural Gas Pneumatic Devices 

with Low-Bleed Pneumatic Devices 

Current high-bleed pneumatic control systems, which are approximately 26% of current 

installed pneumatic control systems for pipelines, are based on high-bleed compressed methane. 

An alternative designed is based on low-bleed. Replacing high-bleed with low-bleed devices is 

estimated to reduce methane emissions from the control system by 90%.118-119 Taking into 

account that methane vented from high-bleed pneumatic control systems is a small fraction of 

total methane emissions from the pipeline mode, the estimated potential reductions in modal 

GHG emissions and energy use are 0.6% and 0.2%, respectively. 

8.2 Connecting Method ―Best Practice 5-3: “Hot Tap” Pipeline Connecting Method 

Methods for constructing new pipeline connections for an existing, operational pipeline 

usually result in significant venting of natural gas. In contrast, the “hot tap” pipeline 

connecting method is a commercially available technology that reduces GHG emissions. This 

method avoids the need for venting natural gas. It involves attaching a branch pipeline 

connection on the outside of an operating pipeline and cutting out the inside pipeline wall. This 

practice would reduce natural gas emission.120-122 The estimated potential reductions in modal 

GHG emissions and energy use are 1.9% and 0.5%, respectively. 

8.3 Maintenance 

In the natural gas industry, fugitive emissions of methane are due to leaking pipelines, 

meters and regulating equipment. The improvement of inspection and maintenance processes 

can be a cost-effective way to reduce methane emissions. 

8.3.1 Best Practice 5-4: Transfer Compression 

During the pipeline maintenance process, a section of pipe is often isolated and taken out 

for maintenance, and methane is vented from the isolated section. An alternative to venting is 

to transfer the natural gas in the isolated section to an operating section of the pipeline, thereby 

avoiding loss of methane. A system for doing this is a transfer compressor unit, which is 

commercially available. Several transfer compressors can be operated simultaneously to 

increase the methane recovery rate.121-123 The estimated potential reductions in modal GHG 

emissions and energy use are 0.1% and 0.02%, respectively. 

8.3.2 Best Practice 5-5: Inline Inspection 

Pipeline flaws, especially stress corrosion cracking (SCC), cause pipeline failure that are 
84

of safety concern and that lead to fugitive methane emissions. A pipeline inline inspection (ILI) 

tool, referred to as “smart pig,” was originally designed to inspect internal pipeline conditions, 

such as dents or metal loss, by using ultrasound.124 A ultrasound inline inspection tool based on 

a newer design can detect not only dents or metal loss, but also SCC. This new tool is able to 

locate more pipeline flaws. By identifying and correcting such flaws sooner, fugitive methane 

emissions can be reduced.121 The estimated potential reductions in modal GHG emissions and 

energy use are 1.3% and 0.4%, respectively. 

8.4 Summary of Potential Best Practices for the Pipeline Mode 

All five potential best practices for the pipeline mode, organized by three subgroups, are 

summarized in Table 8-1. They are in table format for the convenience of readers. 

8.5 Comparisons of the Modal GHG Emissions Reductions for the Best Practices 

Figure 8-1 summarizes the variability among the potential best practices with respect to 

estimated reductions in modal GHG emissions. 

These percentage reductions in modal GHG emissions range from 0.1 to 1.9 percent 

when comparing individual best practices. 

8.6 Quantitative Cost Results for the Pipeline Mode 

Quantitative cost results for the best practices for which sufficient information was 

available to perform such assessments are summarized in standardized reporting tables, which 

are given in Appendix E. In contrast, qualitative assessment results for the best practices which 

have a lack of sufficient information from which to quantify costs are summarized in simplified 

summary tables individually, which are also given in Appendix E. To date, there is sufficient 

information for three best practices upon which to make quantitative assessments. The other 

two best practices are assessed qualitatively. 

The best practices assessed quantitatively include: convert natural gas pneumatic 

controls to instrument air; replace high bleed natural gas pneumatic devices with low bleed 

pneumatic devices; and “hot tap” pipeline connecting method. Table 8-2 summarizes the 

quantitative assessment results of modal GHG emissions reductions, modal energy use 

reductions, annualized cost, energy cost saving, net savings, net savings per unit of GHG 

emissions reductions, net savings per unit of energy use reduction, and simple pay-back periods 

for these three selected best practices. 
85

Table 8- 1. List and Description of Potential Best Practices for the Pipeline Mode 

Subgroup Type of 

Strategies Description 

Technology 

5-1. Convert Natural Gas Pneumatic Controls to Instrument Air

Compressed air powered pneumatic control systems, which are the 

alternative to currently used natural gas powered systems, are commercially 

available devices that reduce GHG emissions. There are approximately 

90,000 to 130,000 pneumatic control devices used in natural gas pipelines. 

They are used to actuate isolation valves, control liquid level, and regulate 

gas flow and pressure at compressor stations, pipelines, and storage 

facilities. These systems are usually powered by readily available 

high-pressure natural gas, and natural gas is constantly bled from these 

devices. Thus, these devices contribute to GHG emissions.117 EPA

estimates that approximately 8.46×109

 tons methane were emitted in 2003

for pipeline operation.1

 Conversion of natural gas-powered pneumatic 

control systems to compressed instrument air powered systems can reduce 

methane emissions.117 Taking into account the electricity energy needed 

for powering the compressed instrument air powered systems, the estimated 

potential reductions in modal GHG emissions and energy use are 0.5% and 

0.1%, respectively. However, to implement instrument air systems, utility 

or self-generated electrical power should be available on site. 

Process 

Control 

Device 

Improvement 

Technology 

5-2. Replace High-Bleed Natural Gas Pneumatic Devices with Low-Bleed 

Pneumatic Devices

Low-bleed natural gas powered pneumatic control systems are commercially 

available. Of the existing natural gas powered control devices, 26% of 

them are high-bleed devices. Most high-bleed devices can be replaced or 

retrofitted with low-bleed devices, thereby reducing the per-device methane 

emissions by 90%.118-119 Taking into account that methane vented from 

high-bleed pneumatic control systems is a fraction of total methane emission

from the pipeline mode, the estimated potential reductions in modal GHG 

emissions and energy use are 0.6% and 0.2%, respectively. 

Connecting 

Method Technology 

5-3. “Hot Tap” Pipeline Connecting Method

Methods for constructing new pipeline connections for an existing, 

operational pipeline usually result in significant venting of natural gas. In 

contrast, the “hot tap” pipeline connecting method is a commercially 

available technology that reduces GHG emissions. Traditional connecting 

methods usually vent a significant amount of natural gas into atmosphere 

during their operation. This method avoids the need for venting natural 

gas. It involves attaching a branch pipeline connection on the outside of an 

operating pipeline and cutting out the inside pipeline wall. This practice 

would reduce natural gas emission.120-122 The estimated potential 

reductions in modal GHG emissions and energy use are 1.9% and 0.5%, 

respectively. Natural gas cost saving is generally sufficient to justify the 

costs for hot tap method instead of the costs for traditional connecting 

methods. The simple pay-back period for this practice is approximately 12 

months. 

Continued on next Page
86

Table 8-1. Continued 

Subgroup Type of 

Strategies Description 

Technology 

5-4. Transfer Compression

During the pipeline maintenance process, a section of pipe is often isolated 

and taken out for maintenance, and a significant amount of methane is 

vented into the atmosphere. A transfer compressor is a commercial 

available system that reduces methane emissions in this process. It pumps 

natural gas from the isolated pipeline section to an operational section of the 

pipeline section, thereby decreasing the amount of vented methane. 

Several transfer compressors, which can be mounted on trucks, are operated 

at the same time.121,123 The estimated potential reductions in modal GHG 

emissions and energy use are 0.1% and 0.02%, respectively. 

Maintenance 

Technology 

5-5. Inline Inspection

Pipeline flaws, especially stress corrosion cracking (SCC), cause pipeline 

failures that are of safety concern and that increase fugitive methane

emissions. In order to ensure the integrity of the pipeline systems, these 

flaws must be detected and repaired. A pipeline inline inspection (ILI) 

tool, referred to as “smart pig,” is a commercially available device that helps 

in detection of pipeline flaws.124 By correcting such flaws, fugitive methane 

emissions are avoided. A newer design for an ultrasound inline inspection 

tool has been developed. This new-designed tool can detect not only dents 

or metal loss, but also SCC. The new tool is more sensitive in detecting 

problems, thereby enabling identification of problems sooner. This 

upgraded tool can find more flaws in the pipeline system and, therefore, 

enable quickly corrective action lead to larger reductions in fugitive methane 

emissions.121 The estimated potential reductions in modal GHG emissions

and energy use are 1.3% and 0.4%, respectively. 
87

0

0.5

1

1.5

2

2.5

5-1 5-2 5-3 5-4 5-5

Best Practice Number for the Pipeline Mode 

Figure 8- 1. Reductions in Modal GHG Emissions for Best Practices for the Pipeline 

Mode 

All three best practices produce net cost savings. These savings are the net result of 

substantial costs offset by substantial savings based on reduced energy usage. Although the hot 

tap method has the potential to achieve larger magnitudes of GHG emissions reductions and 

higher amount of net savings than those of the other two practices, all three practices appear to 

have a similar magnitude of cost-effectiveness when normalized by GHG emissions reductions. Modal GHG Emissions Reductions (%) 
88

Table 8- 2. Summary Table for the Comparison of the Quantitative Cost Results for 

Selected Best Practices for the Pipeline Mode.a 

Best Practice Number 5-1 5-2 5-3 

Name 

Convert Natural Gas 

Pneumatic Controls to 

Instrument Air 

Replace 

High-Bleed Natural 

Gas Pneumatic 

Devices with 

Low-Bleed 

Pneumatic Devices 

“Hot Tap” Method 

Subgroup Process Control Device 

Improvement 

Process Control 

Device 

Improvement 

Connecting 

Method 

Responsible Parties 70, 71, 72, 73 70, 71, 72, 73 70, 71, 72, 73 

Target Parties 26, 27, 28 26, 27, 28 26, 27, 28, 29 

Target GHGs CH4 CH4 CH4

Strategy Types Technology Technology Technology 

Developmental Status C C C 

Modal GHG Emission 

Reduction 

(106

 ton CO2 eq./year) 

0.7 0.8 2.5 

Modal Energy Use Reduction 

(1012 BTU/year) 1 2 5 

Annualized Costs 

($ 106

/year) 1.7 1.8 11 

Annual Energy Cost Saving 

($ 106/year) 13 15 51 

Net Saving ($ 106/year) 12 13 40 

Net Saving per Unit of GHG 

Emissions Reductions 

($/ton CO2 eq.) 

18 18 16 

Net Saving per Unit of 

Energy Use Reduction 

($/ton CO2 eq.) 

9.6 8.8 7.8 

Simple Pay-back Period 

(years) 0.3 0.9 0.2 

a

 These assessments are based on the assumptions that these best practices reach their potential 

maximum market shares in 2025. Cost results are presented only for those best practices for which 

adequate data were available. 
89

9.0 SUMMARY AND COMPARISON OF GHG EMISSIONS REDUCTIONS FOR 

ALL FREIGHT TRANSPORTATION MODES 

A total of 59 strategies have been identified as best practices in freight transportation. 

There are 33, 6, 10, 5, and 5 best practices for the truck, rail, air, water, and pipeline modes, 

respectively. Approximately half of the total number of best practices are for the truck mode. 

The purpose of this Chapter is to: 

z summarize the potential for reductions in GHG emissions, Energy use or Refrigerant 

Use (GERU) for individual best practices and subgroups; 

z summarize and evaluate the variability in GERU reductions and cost-effectiveness 

of the best practices among different modes, based on quantitative assessment 

results; and 

z evaluate the potential impact of intermodal substitutions. 

9.1 Truck Mode 

Total GHG emissions reductions for all five modes are mainly attributable to reductions 

in energy use. However, a small portion of emissions reductions for the truck mode are 

contributed by reductions in refrigerant use or leakage. Table 9-1 summarizes potential 

individual and aggregate reductions in GHG emissions and energy use for best practices for the 

truck mode. These reductions are summarized in four ways: 

(1) The potential per-device reductions in GHG emissions and energy use for an 

individual best practice, which are the percentage reductions compared to emissions 

and energy use of a device that does not use the practice. 

(2) The potential reductions in modal GHG emissions and energy use for an individual 

best practice, which are the percentage reductions for a practice when it is used on all 

applicable devices for a mode. These reductions are compared to modal total 

emissions and energy use without use of this practice. 

(3) Percentage contributions of a subgroup to total reductions in modal GHG emissions 

and energy use if all best practices are implemented. 

(4) The magnitude of aggregate reductions in modal GHG emissions and energy use in 

2025 if all best practices are used for each subgroup. 

The reductions in refrigerant use for best practices within the air conditioning 

improvement subgroup (I.D. No. 1-6 to 1-10) are not included in Table 9-1. Four of the five 

best practices in this subgroup have the potential to reduce GHG emissions by reducing 
90

refrigerant leakage rate or use of low global-warming-potential refrigerants. Their potential 

modal GHG emissions reductions range from 0.9% to 2.5%. A small portion of the potential 

total GHG emissions reduction by 2025 for all 33 best practices for the truck mode is attributed 

to reduced refrigerant leakage rate or use of low GWP refrigerants. 

Some subgroups include best practices with complex conditions, such as mutual 

exclusion, interaction, and technological barriers. Some interactions exist not only among best 

practices within a subgroup, but also among best practices from different subgroups. 

(1) Anti-Idling (I.D. Nos. 1-1 to 1-5 in Table 9-1) 

Auxiliary power units are the basis for the estimated GHG emissions reductions for 

the anti-idling subgroup. Five best practices are mutually exclusive. The top two 

practices are auxiliary power units and direct-fired heaters with thermal storage units. 

The former is chosen here because operation of the later requires battery power and 

inhibits its acceptance by the market. 

(2) Air Conditioning System Improvement (I.D. Nos. 1-6 to 1-10 in Table 9-1) 

The assessment results of the estimated GHG emissions reductions for this 

subgroup are based on the choice of CO2 as a refrigerant. 

Three alternative refrigerants that could be used as best practices are mutually 

exclusive, since only one refrigerant can be used in an air conditioning system. CO2 is 

chosen here because it has the lowest GWP compared to the other candidate refrigerants 

and its potential reductions in modal GHG emissions are the highest. 

There is interaction between enhanced air conditioning systems with respect to 

direct emissions and low-GWP refrigerants. At a given leakage rate, the systems using 

low-GWP refrigerant contribute less GHG emissions than those using CFC-152a. 

Thus, the potential GHG emissions for enhanced air conditioning systems for direct 

emission are reduced if CFC-152a refrigerant is replaced by any of the low-GWP 

refrigerants. 

 There is also interaction between enhanced air conditioning systems for indirect 

emissions and low-GWP refrigerants. More energy may be needed to operate some 

low-GWP refrigerant systems. For example, a propane based refrigerant system uses 

about 10% more energy for the operation of vehicle air conditioners and increases 

indirect GHG emissions The potential GHG emissions reduction for enhanced air 

conditioning systems for indirect emission may increase if alternative refrigerants are 

used. 

(3) Aerodynamic Drag Reduction (I.D. Nos. 1-11 to 1-16 in Table 9-1) 

This subgroup includes two best practices, pneumatic aerodynamic drag reduction 

(I.D. No. 1-14) and planar boat tail plates on tractor-trailers (I.D. No. 1-15), which are 
91

mutually exclusive. They are mutually exclusive because both of these best practices 

are installed on the tails of tractor-trailer for aft-end drag reduction. They cannot both 

be implemented on the same truck. The former is chosen here because reductions by 

the former are estimated to be higher than the reductions by the latter. There is 

interaction between pneumatic aerodynamic drag reduction systems and some truck 

configurations. For example, the dimensions of the tractor-trailer gap may inhibit the 

reduction of aerodynamic drag achievable via this system. Thus, adopting another best 

practice that reduces the tractor-trailer gap may enhance the reduction potential of this 

practice. The available data for the effectiveness of aerodynamic drag reductions are 

based on individual field tests that do not take into account these interactions, and thus 

there is not an empirical basis for quantitatively estimating the effect of such 

interactions on reductions in vehicle fuel consumption.43 

(4) Tire Rolling Resistance Improvement (I.D. Nos. 1-17 to 1-20 in Table 9-1) 

This subgroup includes two best practices, low rolling-resistance tires (I.D. No. 

1-19) and wide-base tires (I.D. No. 1-20), which are mutually exclusive. They are 

mutually exclusive, since they cannot both be implemented on the same truck. Both of 

them can reduce GHG emissions by the same magnitude, so the results of the 

assessment are not sensitive to the choice between these two approaches. The 

estimates for low rolling-resistance tires are used here. 

(5) Transmission Improvement (I.D. Nos. 1-23 to 1-24 in Table 9-1) 

There is interaction between advanced transmissions (I.D. No. 1-23) and 

transmission friction reduction through low-viscosity transmission lubricants (I.D. No. 

1-24). Advanced transmissions are designed to reduce internal friction, such as by 

reduction of gear surface roughness and by the use of low-friction coatings. Lubricants 

are also used to reduce gear contact friction. Thus, the total reduction may not be a 

simple linear combination of the reductions of these two practices. However, there is a 

lack of data with which to quantify the impact of the interaction. Thus, a simple linear 

combination of the reductions is applied. 

(6) Diesel Engine Improvement (I.D. Nos. 1-25 to 1-29 in Table 9-1) 

For the diesel engine improvement subgroup, there is an interaction between two 

practices: improved fuel injectors (I.D. No. 1-27); and turbocharged, direct injection to 

improved thermal management (I.D. No. 1-28). The former improves the fuel 

injection systems for all trucks. The latter improves the fuel injection systems for 

medium-duty trucks. Most heavy-duty trucks already have turbocharged systems. 

Since the former focuses on the improvement of fuel injection system and the latter also 

involves a change in the fuel injection system, the combined reduction may not be a 
92

simple linear combination of the reductions of these two practices if implemented on the 

same. However, there is a lack of data with which to quantify the impact of the 

interaction. Thus, a simple linear combination of the reductions is applied for the 

former practice for heavy duty trucks and the latter practice for medium duty trucks. 

(7) Accessory Load Reduction (I.D. Nos. 1-30 to 1-31 in Table 9-1) 

Accessory load reduction can be achieved by conversion of mechanical auxiliary 

loads to electrically-operated ones. Furthermore, the electric power for auxiliaries can 

be obtained from an source separate from the truck base engine, such as a small fuel cell 

system or a small diesel engine with an alternator. Thus, these two best practices have 

common technology with respect to auxiliary loads, but differ in terms of the electric 

power supply system for the auxiliaries. Therefore, although the same kinds of 

electrically-operated auxiliary components can be used for both best practices, they 

differ in a mutually exclusive way because they are a based on different energy 

conversion systems. For purpose of making an upper bound estimate of the potential 

for auxiliary load reduction, the fuel cell-based energy conversion system with 

electrically operated auxiliaries is chosen, since this practice has the potential to reduce 

GHG emissions more than the small diesel engine-based system. 

The two most important subgroups for GHG emissions reduction are diesel engine 

improvement (I.D. Nos. 1-25 to 1-29) and aerodynamic drag reduction (I.D. Nos. 1-11 to 1-16). 

These two subgroups contribute 29 and 16 percent, respectively, to the estimated total modal 

GHG emissions reductions. 

9.2 Rail Mode 

Table 9-2 summarizes potential individual and aggregate reductions in GHG emissions 

and energy use for best practice for the rail mode. These reductions are summarized in four 

ways, which are the same as those for Table 9-1. 

A subgroup, anti-idling (I.D. Nos. 2-1 to 2-3), includes best practices that are mutually 

exclusive. Rail companies usually use different types of locomotives for long-haul versus yard 

switching service. The latter locomotives typically have larger engines (e.g., 5,000 hp) than the 

former (e.g., 2,000 hp). Assuming that the national ratio of yard switchers to total locomotives 

is the same as the ratio for Union Pacific (UP), the largest railroad company in the U.S., 

approximately 71% of locomotives are long-haul.125 The remainder are switchers. Best 

practice 2-1 is applicable to both long-haul locomotives and switchers. Best practices 2-2 and 

2-3 are applicable only to switchers. Although best practice 2-2 has the potential to reduce 
93

Table 9- 1. Potential Best Practices for the Truck Mode and the Estimated Reductions in GHG Emission

Subgroup I.D. No. Brief Name of Best Practice 

Developmental Status 

a

Potential Per-device Reductions 

in GHG Emissions (%)b 

Potential Per-device Reductions 

in Energy Use (%)

b

 

Potential Reductions in Modal 

GHG Emissions (%)

c

 

Potential Reductions in Modal 

Energy Use (%)

c

 

Percentage Contribution of a 

Subgroup to Total Reductions in 

Modal GHG Emissions (%)

d

 

Percentage Contribution of a 

Subgroup to Total Reductions in 

Modal Energy Use (%)

d

 

Potential Aggregate GHG 

Emission Reduction in 2025 for 

Each Subgroup 

6

1-1 Off-Board Truck Stop Electrification C 1.53 1.45 0.33 0.31 1-2 Truck-Board Truck Stop Electrification C 1.83 1.88 0.39 0.41 1-3 Auxiliary Power Units C 9.62 9.87 2.08 2.13 1-4 Direct-Fired Heaters C 4.85 5.00 1.05 1.08 

Anti-Idling 

1-5 Direct-Fired Heaters with Thermal Storage Units P 13.33 13.74 2.88 2.97 

3.64 4.50 15.00 

1-6 Enhanced Air Conditioning System I - for Direct Emissions P 0.88 - f 0.88 - f1-7 

Enhanced Air Conditioning System II - for Indirect Emissions 

C 0.18 0.19 0.18 0.19 

1-8 Alternative Refrigerants - CO2 N 2.47 - f 2.47 - f1-9 Alternative Refrigerants - HFC-152a N 2.35 - f 2.35 - f

Air Conditioning 

System Improvement 

1-10 Alternative Refrigerants - HC N 2.46 - f 2.46 - f

4.65 0.40 19.15g 

Continued on next page 
94

Table 9-1. Continued 

Subgroup I.D. No. Brief Name of Best Practice 

Developmental Status 

a

Potential Per-device Reductions in 

GHG Emissions (%)b 

Potential Per-device Reductions in 

Energy Use (%)

b

 

Potential Reductions in Modal GHG 

Emissions (%)

c

 

Potential Reductions in Modal 

Energy Use (%)

c

 

Percentage Contribution of a 

Subgroup to Total Reductions in 

Modal GHG Emissions (%)

d

 

Percentage Contribution of a 

Subgroup to Total Reductions in 

Modal Energy Use (%)

d

 

Potential Aggregate GHG 

Emission Reduction in 2025 for 

Each Subgroup 

6

1-11 Cab Top Deflector, Sloping Hood and Cab Side Flares C 1.90 1.96 1.43 1.47 1-12 

Closing and Covering of Gap Between Tractor and Trailer, Aerodynamic Bumper, Underside Air Baffles, and Wheel Well Covers 

C 2.37 2.44 2.37 2.44 

1-13 Trailer or Van Leading and Trailing Edge Curvatures C 1.24 1.28 1.24 1.28 1-14 Pneumatic Aerodynamic Drag Reduction N 4.62 4.76 2.17 2.24 1-15 Planar Boat Tail Plates on a Tractor-Trailer N 8.01 8.26 3.76 3.88 

Aerodynamic Drag 

Reduction 

1-16 Vehicle Load Profile Improvement C 2.37 2.44 0.43 0.44 

16.17 19.98 66.56 

1-17 Automatic Tire Inflation Systems C 0.78 0.80 0.56 0.58 1-18 Wide-Base Tires C 2.83 2.91 2.03 2.10 1-19 Low-Rolling-Resistance Tires C 2.83 2.91 2.83 2.91 

Tire Rolling 

Resistance 

Improvement 1-20 Pneumatic Blowing to Reducing Rolling Resistance N 1.15 1.19 0.54 0.56 

6.88 8.50 28.33 

Hybrid Propulsion 1-21 Hybrid trucks N 40.27 41.52 3.40 3.50 5.95 7.36 24.50 

Weight Reduction 1-22 Lightweight Materials P 4.62 4.76 4.62 4.76 8.10 10.00 33.32 

1-23 Advanced Transmission P 0.97 1.00 0.97 1.00 

Transmission Improvement 1-24 

Transmission Friction Reduction through Low-Viscosity Transmission Lubricants 

C 0.97 1.00 0.92 0.95 3.31 4.10 13.64 

Continued on next page 
95

Table 9-1. Continued 

Subgroup I.D. No. Brief Name of Best Practice 

Developmental Status a

Potential Per-device Reductions in 

GHG Emissions (%)b 

Potential Per-device Reductions in 

Energy Use (%)b 

Potential Reductions in Modal 

GHG Emissions (%)c 

Potential Reductions in Modal 

Energy Use (%)c 

Percentage Contribution of a 

Subgroup to Total Reductions in 

Modal GHG Emissions (%)d 

Percentage Contribution of a 

Subgroup to Total Reductions in 

Modal Energy Use (%)d 

Potential Aggregate GHG 

Emission Reduction in 2025 

for Each Subgroup 

6

1-25 

Engine Friction Reduction through Low-Viscosity Engine Lubricants 

C 1.90 1.96 1.81 1.86 

1-26 Increased Peak Cylinder Pressures C 3.73 3.85 3.07 3.16 1-27 Improved Fuel Injectors P 5.49 5.66 5.49 5.66 1-28 Turbocharged, Direct Injection to Improved Thermal Management C 4.62 4.76 0.82 0.85 

Diesel Engine 

Improvement 

1-29 Thermoelectric Technology to Recovery Waste Heat N 6.35 6.54 5.22 5.38 

28.75 35.52 118.31 

Accessory Load 1-30 Electric Auxiliaries C 1.43 1.48 1.43 1.48 

Reduction 1-31 Fuel-Cell-Operated Auxiliaries N 5.49 5.66 5.49 5.66 9.62 11.89 39.60 

Modifications in 

Driver Operational 

Practice 

1-32 Truck Driver Training Program C 3.69 3.80 3.10 3.19 5.43 6.70 22.33 

 1-33 B20 Biodiesel Fuel for Trucks C 8.34 -8.30 4.27 -4.25 7.49 -8.92 30.81 

Total for the Truck 

Mode - - 57.06h 47.61h 100.00 100.00 411.54 

a Developmental status: N = new concepts; P = pilot tests; C = commercially available systems. New concepts include basic research activities, 

and experiments at laboratory level. Pilot tests include testing prototype vehicles and demonstration projects. Commercially available systems 

implemented now. b Potential per-device reductions in GHG emissions or energy use are percentage reductions compared to GHG emissions (energy use) of a device w

c Potential reductions in modal GHG emissions or energy use are estimated based on the difference in 2025 modal GHG emissions or energy use w

best practice divided by the total modal GHG emissions or energy use if no best practices are implemented. d Percentage contribution of a subgroup to total reductions is defined by dividing the percentage reductions for a subgroup by total modal reduction

e These reductions are estimated based on the difference between 2025 modal GHG emissions or energy use with and without implementation of th

practices of the subgroup.. f These best practices reduce refrigerant leakage rate or use low GWP refrigerants. 

g GHG emission reduction here are contributed by both energy use reduction and refrigerant leakage rate reduction or using low GWP refrigerants. h Total potential reductions in GHG emissions and energy use exclude the reductions contributed by the strategies that are not the highest one in the 
96

Table 9- 2. Potential Best Practices for the Rail Mode and the Estimated Reductions in GHG Emission

Subgroup I.D. No. Brief Name of Best Practice 

Developmental Status 

a

Potential Per-device Reductions 

in GHG Emissions (%)b 

Potential Per-device Reductions 

in Energy Use (%)

b

 

Potential Reductions in Modal 

GHG Emissions (%)

c

 

Potential Reductions in Modal 

Energy Use (%)

c

 

Percentage Contribution of a 

Subgroup to Total Reductions in 

Modal GHG Emissions (%)

d

 

Percentage Contribution of a 

Subgroup to Total Reductions in 

Modal Energy Use (%)

d

 

Potential Aggregate GHG 

Emission Reduction in 2025 for 

Each Subgroup 

(10

6

TCO)

e

2-1 

Combined Diesel Powered Heating System and Auto Engine Start/stop System 

P 3.81 3.81 3.62 3.62 

2-2 Battery-Diesel Hybrid Switching Locomotive C 35.00 35.00 1.75 1.75 Anti-Idling 2-3 Plug-In Units C 11.50 8.80 0.58 0.44 

27.34 60.90 3.43 

Weight Reduction 2-4 Light Weight Materials C 4.76 4.76 4.76 4.76 24.25 53.98 3.05 

Rolling Resistance 

Improvement 2-5 Lubrication Improvement P 4.00 4.00 4.00 4.00 20.38 45.36 2.56 

Alternative Fuel 2-6 B20 Biodiesel Fuel for Locomotives N 8.60 -8.30 5.50 -5.31 28.04 -60.24 3.52 

Total for the Rail 

Mode - - 19.63f 8.82f 100.00 100.00 12.56 

a Developmental status: N = new concepts; P = pilot tests; C = commercially available systems. New concepts include basic research activities, 

and experiments at laboratory level. Pilot tests include testing prototype vehicles and demonstration projects. Commercially available systems 

implemented now. 

b Potential per-device reductions in GHG emissions or energy use are percentage reductions compared to GHG emissions (energy use) of a device wc Potential reductions in modal GHG emissions or energy use are estimated based on the difference in 2025 modal GHG emissions or energy use w

best practice divided by the total modal GHG emissions or energy use if no best practices are implemented. 

d Percentage contribution of a subgroup to total reductions is defined by dividing the percentage reductions for a subgroup by total modal reductione These reductions are estimated based on the difference between 2025 modal GHG emissions or energy use with and without implementation of th

practices of the subgroup..

f Total potential reductions in GHG emissions and energy use for the rail mode exclude the reductions contributed by the strategies that are not the 

mutual exclusion. 
97

per-vehicle GHG emissions more than the other two best practices, it is only applicable to 

switchers, which are estimated to account for only 5% of total locomotive fuel use.117 Best 

practice 2-1 has a larger over-all impact even though the per locomotive reduction is not as large, 

because it can be applied to all locomotives. 

The two most important subgroups for GHG emissions reduction are alternative fuel (I.D. 

No. 2-6) and anti-idling (I.D. Nos. 2-1 to 2-3). These two subgroups both contribute 28 and 27 

percent, respectively, to the estimated total reduction in modal GHG emissions. 

9.3 Air Mode 

Table 9-3 summarizes potential individual and aggregate reductions in GHG emissions 

and energy use for best practices for the air mode. These reductions are summarized in four 

ways, which are the same as those for Table 9-1. 

A subgroup, aerodynamic drag reduction (I.D. Nos. 3-1 to 3-4), includes two best 

practices that are mutually exclusive. Blended winglet (I.D. No. 3-3) and spiroid tip (I.D. No. 

3-4) are mutually exclusive because both of these best practices are designed to reduce 

lift-induced drag and cannot both be implemented on the same airplane. The reductions by the 

former are estimated to be higher than the reductions by the latter. Therefore, the former is 

used as the basis for the analysis. 

The two most important subgroups for GHG emissions reduction are engine 

improvement (I.D. No. 3-10) and aerodynamic drag reduction (I.D. Nos. 3-1 to 3-4). These two 

subgroups contribute 38 and 28 percent, respectively, to the estimated total modal GHG 

emissions reductions.

9.4 Water Mode 

Table 9-4 summarizes potential individual and aggregate reductions in GHG emissions 

and energy use for best practices for the water mode. These reductions are summarized in four 

ways, which are the same as those for Table 9-1. 

A subgroup, propeller system improvement (I.D. Nos. 4-1 to 4-3), includes best practices 

that are mutually exclusive. Each of them are based on different propeller designs. They 

cannot be implemented simultaneously on the same ship. To provide an upper bound on the 

potential benefits of this subgroup, the best practice that has the largest estimated reductions in 

fuel use and GHG emissions is selected as the basis for the analysis of modal reductions. The 

selected best practice is an auxiliary free-rotating propulsion device behind the main propeller. 
98

Table 9- 3. Potential Best Practices for the Air Mode and the Estimated Reductions in GHG Emission

Subgroup I.D. No. Brief Name of Best Practice 

Developmental Status 

a

Potential Per-device Reductions in 

GHG Emissions (%)b 

Potential Per-device Reductions in 

Energy Use (%)

b

 

Potential Reductions in Modal GHG 

Emissions (%)

c

 

Potential Reductions in Modal 

Energy Use (%)

c

 

Percentage Contribution of a 

Subgroup to Total Reductions in 

Modal GHG Emissions (%)

d

 

Percentage Contribution of a 

Subgroup to Total Reductions in 

Modal Energy Use (%)

d

 

Potential Aggregate GHG Emission 

Reduction in 2025 for Each 

Sb

3-1 Surface Grooves P 1.60 1.60 1.60 1.60 3-2 Hybrid Laminar Flow Technology N 6.00 6.00 6.00 6.00 3-3 Blended Winglet C 2.00 2.00 2.00 2.00 

Aerodynamic Drag 

Reduction 

3-4 Spiroid Tip P 1.65 1.65 1.65 1.65 

27.79 27.79 5.66 

Air Traffic 

Management 3-5 Air traffic Management Improvement N 6.00 6.00 6.00 6.00 17.37 17.37 3.54 

3-6 Airframe Weight Reduction N 2.00 2.00 2.00 2.00 Weight Reduction 3-7 Non-Essential Weight Reduction N 1.00 1.00 1.00 1.00 8.69 8.69 1.77 3-8 

Ground-Based Equipment as an Alternative to Auxiliary Power Units 

Ground Support P 

Equipment 

Improvement 3-9 Electric or Hybrid Heavy Duty Delivery Trucks P 

2.94 2.94 2.94 2.94 8.51 8.51 1.73 

Continued on next page 
99

Table 9-3. Continued 

Subgroup I.D. No. Brief Name of Best Practice 

Developmental Status 

a

Potential Per-device Reductions in 

GHG Emissions (%)b 

Potential Per-device Reductions in 

Energy Use (%)

b

 

Potential Reductions in Modal 

GHG Emissions (%)

c

 

Potential Reductions in Modal 

Energy Use (%)

c

 

Percentage Contribution of a 

Subgroup to Total Reductions in 

Modal GHG Emissions (%)

d

 

Percentage Contribution of a 

Subgroup to Total Reductions in 

Modal Energy Use (%)

d

 

Potential Aggregate GHG 

Emission Reduction in 2025 

fEh Sb

Engine Improvement 3-10 Improved Engine Overall Efficiency C 13.00 13.00 13.00 13.00 37.64 37.64 7.66 

Total for the Air 

Mode - - 34.54f 34.54f 100.00 100.00 20.3

a Developmental status: N = new concepts; P = pilot tests; C = commercially available systems. New concepts include basic research activities, 

and experiments at laboratory level. Pilot tests include testing prototype vehicles and demonstration projects. Commercially available systems 

implemented now. 

b Potential per-device reductions in GHG emissions or energy use are percentage reductions compared to GHG emissions (energy use) of a device wc Potential reductions in modal GHG emissions or energy use are estimated based on the difference in 2025 modal GHG emissions or energy use w

best practice divided by the total modal GHG emissions or energy use if no best practices are implemented. 

d Percentage contribution of a subgroup to total reductions is defined by dividing the percentage reductions for a subgroup by total modal reductione These reductions are estimated based on the difference between 2025 modal GHG emissions or energy use with and without implementation of th

practices of the subgroup..

f Total potential reductions in GHG emissions and energy use for the air mode exclude the reductions contributed by the strategies that are not the h

mutual exclusion. 
100

Table 9- 4. Potential Best Practices for the Water Mode and the Estimated Reductions in GHG Emissio

Subgroup I.D. No. Brief Name of Best Practice 

Developmental Status 

a

Potential Per-device Reductions 

in GHG Emissions (%)b 

Potential Per-device Reductions 

in Energy Use (%)

b

 

Potential Reductions in Modal 

GHG Emissions (%)

c

 

Potential Reductions in Modal 

Energy Use (%)

c

 

Percentage Contribution of a 

Subgroup to Total Reductions in 

Modal GHG Emissions (%)

d

 

Percentage Contribution of a 

Subgroup to Total Reductions in 

Modal Energy Use (%)

d

 

Potential Aggregate GHG 

Emission Reduction in 2025 for 

Each Subgroup 

6e

4-1 Off-Center Propeller C 3.00 3.00 1.50 1.50 4-2 Propeller Boss Cap with Fins C 4.00 4.00 2.00 2.00 Propeller System 

Improvement 4-3 Auxiliary Free-Rotating Propulsion Device behind the 

Main Propeller 

C 6.00 6.00 3.00 3.00 

68.44 174.93 3.65 

Anti-Idling 4-4 Shoreside Power for Marine Vessels at Ports P 13.00 -3.20 0.16 -0.04 3.71 -2.33 0.20 

Alternative Fuel 4-5 B20 Biodiesel Fuel for Ships N 8.14 -8.30 1.22 -1.25 27.85 -72.59 1.48 

Total for the Water 

Mode - - 4.38f 1.72f 100.00 100.00 5.33 

a Developmental status: N = new concepts; P = pilot tests; C = commercially available systems. New concepts include basic research activities, 

and experiments at laboratory level. Pilot tests include testing prototype vehicles and demonstration projects. Commercially available systems 

implemented now.b Potential per-device reductions in GHG emissions or energy use are percentage reductions compared to GHG emissions (en

using this practice. 

c Potential reductions in modal GHG emissions or energy use are estimated based on the difference in 2025 modal GHG emissions or energy use w

best practice divided by the total modal GHG emissions or energy use if no best practices are implemented. 

d Percentage contribution of a subgroup to total reductions is defined by dividing the percentage reductions for a subgroup by total modal reductione These reductions are estimated based on the difference between 2025 modal GHG emissions or energy use with and without implementation of th

practices of the subgroup..

f Total potential reductions in GHG emissions and energy use for the water mode exclude the reductions contributed by the strategies that are not th

mutual exclusion. 
101

The two most important subgroups for GHG emissions reduction are propeller system 

improvement (I.D. Nos. 4-1 to 4-3) and alternative fuel (I.D. No. 4-5). These two subgroups 

contribute 68 and 28 percent, respectively, to the estimated total modal GHG emissions 

reductions. 

9.5 Pipeline Mode 

GHG emissions reductions for the pipeline mode are based upon energy use reductions, 

which include petroleum fuel use reductions and natural gas emission reductions. Table 9-5 

summarizes potential individual and aggregate reductions in GHG emissions and energy use for 

best practices for the pipeline mode. These reductions are summarized in four ways, which are 

the same as those for Table 9-1. 

The most important subgroup for GHG emissions reduction is connecting method (I.D. 

Nos. 5-3). This subgroup contributes 44 percent to the estimated total modal GHG emissions 

reductions. 

9.6 Intermodal Comparisons 

The purpose of this section is to summarize and discuss: 

• comparisons of total reductions in relative and absolute modal GHG emissions in 2025 

for multiple best practices for all modes; 

• annual reductions in modal GHG emissions, energy use reduction, and 

cost-effectiveness of selected best practices for which there is sufficient information 

for quantitative analysis; and 

• impacts of intermodal substitutes if intermodal shifts are available. 

9.6.1 Total Modal GHG Emissions Reductions 

Modal GHG emissions reductions in this section are estimated based on the difference 

between 2025 modal emissions with or without implementation of the representative best 

practices. There is substantial variability among the best practices in terms of their potential 

percentage reductions in modal GHG emissions. The variations in reductions among individual 

practices range from 0.2 to 5.5 percent for the truck mode, 0.6 to 5.5 percent for the rail mode, 

1.0 to 13.0 percent for the air mode, 0.2 to 3.0 percent for the water mode, and 0.1 to 1.9 percent 

for the pipeline mode. The average reductions for a best practice are 2.2, 3.4, 2.3, 1.6, and 0.9 

percent for the truck, rail, air, water, and pipeline modes, respectively. 
102

Table 9- 5. Potential Best Practices for the Pipeline Mode and the Estimated Reductions in GHG Emissi

Subgroup I.D. No. Brief Name of Best Practice 

Developmental Status 

a

Potential Per-device Reductions in 

GHG Emissions (%)b 

Potential Per-device Reductions in 

Energy Use (%)

b

 

Potential Reductions in Modal GHG 

Emissions (%)

c

 

Potential Reductions in Modal 

Energy Use (%)

c

 

Percentage Contribution of a 

Subgroup to Total Reductions in 

Modal GHG Emissions (%)

d

 

Percentage Contribution of a 

Subgroup to Total Reductions in 

Modal Energy Use (%)

d

 

Potential Aggregate GHG Emission 

Reduction in 2025 for Each 

Subgroup 

(10

6

TCO)

e

5-1 Convert Natural Gas Pneumatic Controls to Instrument Air C 10.00 9.02 0.50 0.13 Process Control 

Device Improvement 5-2 Replace High-Bleed Natural Gas Pneumatic Devices with 

Low-Bleed Pneumatic Devices 

C 90.00 90.00 0.57 0.16 

24.52 23.64 1.40 

Connecting Method 5-3 “Hot Tap” Method C 1.93 0.54 1.93 0.54 43.83 44.35 2.50 

5-4 Transfer Compression C 0.11 0.02 0.07 0.02 Maintenance 5-5 Inline Inspection C 1.32 0.37 1.32 0.37 31.65 32.01 1.81 

Total for the Pipeline 

Mode - - 4.40 1.22 100.00 100.00 5.70 

a Developmental status: N = new concepts; P = pilot tests; C = commercially available systems. New concepts include basic research activities, 

and experiments at laboratory level. Pilot tests include testing prototype vehicles and demonstration projects. Commercially available systems 

implemented now. 

b Potential per-device reductions in GHG emissions or energy use are percentage reductions compared to GHG emissions (energy use) of a device wc Potential reductions in modal GHG emissions or energy use are estimated based on the difference in 2025 modal GHG emissions or energy use w

best practice divided by the total modal GHG emissions or energy use if no best practices are implemented. 

d Percentage contribution of a subgroup to total reductions is defined by dividing the percentage reductions for a subgroup by total modal reductione These reductions are estimated based on the difference between 2025 modal GHG emissions or energy use with and without implementation of th

practices of the subgroup..
103

Within each mode, multiple best practices can be applied simultaneously to achieve total 

2025 modal GHG emissions reductions (compared to projected emissions if no best practices are 

used) of 57, 19, 34, 4, and 4 percent for the truck, rail, air, water, and pipeline modes, 

respectively, depending on the mode, as summarized in Figure 9-1 (a) and (b), which illustrate 

modal percentage reductions categorized by developmental status and target GHGs, respectively. 

N2O emission is not included because its contribution is less than 0.4% of total GHG emissions.

The truck mode is the biggest GHG emissions contributor, and it also has the highest 

GHG emissions reduction potential. The truck mode is estimated to contribute 66 percent of 

freight transportation GHG emissions in 2025 if none of the best practices are adopted. The 

total GHG emissions of this mode in 2025 are estimated to increase 67 percent over 2003 levels. 

If all identified best practices are implemented aggressively, 2025 GHG emissions could be 

reduced by as much as 28 percent compared to 2003 levels. Furthermore, such reductions 

would amount to a 57 percent reduction compared to 2025 GHG emissions if none of the best 

practices are used. 

Each of the other four modes is estimated to contribute 12 percent or less to total freight 

GHG emissions in 2025. If no best practices are implemented, modal GHG emissions in 2025 

from the rail, air, water, and pipeline modes are estimated to increase 49, 65, 28, and 15 percent, 

respectively, compared to 2003 levels. If all identified best practices are implemented 

aggressively, 2025 GHG emissions could increase by 20, 8, 22, and 9 percent, respectively, 

compared to 2003 levels, which is a smaller increase. If all identified best practices are 

implemented aggressively, 2025 GHG emissions could be reduced by 19, 34, 4, and 4 percent, 

respectively, compared to 2025 GHG emissions if none of the best practices are used. 

The magnitude of the estimated potential GHG emissions reductions for each mode in 

2025 ranges from approximately 5 million to 412 million tons CO2 eq., as summarized in Figure 

9-2. The magnitude of the estimated potential GHG emissions reductions for the truck mode in 

2025 is significantly higher than for any of the other four modes. 

Both the total relative and absolute modal 2025 GHG emissions reductions possibilities 

for the truck mode are significantly higher than for the other four modes. The truck mode 

currently contributes more than 60 percent of total energy use and GHG emissions in freight 

transportation. There are more research and development programs focusing on the truck mode. 

Furthermore, an individual strategy for this mode can achieve higher absolute reductions even if 

the percentage reduction is comparable to that of best practices in other modes. For example, 

anti-idling practices for the truck mode are estimated to reduce truck mode GHG emissions by 

2.1%. Anti-idling practices for the rail mode are estimated to reduce rail mode emissions by 

5.4%. However, the magnitude of the truck model GHG emissions reductions is several times 

of the magnitude of the rail mode reductions, even though the percentage reduction is smaller. 
104

0

10

20

30

40

50

60

Truck Rail Air Water Pipeline

New Concepts

Pilot Tests

Commercially Available Systems

(a) Categorized by Developmental Status 

0

10

20

30

40

50

60

Truck Rail Air Water Pipeline

HFC

CH4

CO2

(b) Categorized by Target GHGs 

Figure 9- 1. Total Modal 2025 GHG Emissions Reductions Based on Simultaneous 

Implementation of Multiple Best Practices in Each Mode 

GHG Emissions Reductions (%) GHG Emissions Reductions (%) 
105

0

50

100

150

200

250

300

350

400

450

Truck Rail Air Water Pipeline

New Concepts

Pilot Tests

Commercially Available Systems

Figure 9- 2. Magnitudes of the Total Modal 2025 GHG Emissions Reductions Based on 

Simultaneous Implementation of Multiple Best Practices for Each Mode 

9.6.2 Comparisons of Best Practices Whose Costs Are Assessed Quantitatively 

Current available cost information for best practices whose costs are not sufficient to be 

assessed quantitatively is summarized in simplified summary tables in Appendices. It is critical 

to have cost data for quantitative assessments. While it is clear that many best practices will not 

be considered by potential adopters until adequate cost data is available upon which to estimate 

costs reliably, at this time insufficient data are available to characterize costs reliably for most of 

the best practices identified here. Thus, there is a critical need for future work to better 

characterize these costs. To date, sufficient information has been obtained to assess 13 best 

practices quantitatively. Table 9-6 provides quantitative estimates of reductions in 2025 modal 

GHG emissions and energy use, as well as regarding costs. 

There is substantial variability among these 13 best practices in terms of annual 

reductions in modal 2025 GHG emissions and energy use within their individual modes, which is 

compared to 2025 GHG emissions and energy use without using these best practices. Three 

best practices for the truck mode, which include auxiliary power units, hybrid trucks, and B20 

biodiesel, have the potential to achieve substantial GHG emissions reductions (15×106

 ton CO2

eq./year or more). Two best practices for the truck mode, auxiliary power units and hybrid 

trucks, also have the potential to reduce energy use substantially, by 185×1012 BTU or more. GHG Emissions Reductions (Million Tons CO2 eq.) 
106

Table 9- 6. Quantitative Summary of Reductions in GHG Emissions, Energy Use, and Costs of Select

Mode Truck Rail Water 

I.D. No. 1-1 1-3 1-4 1-21 1-33 2-1 2-2 2-3 2-6 4-5 5-Practice Name 

Off-Board Truck Stop 

Electrification 

Auxiliary Power Units 

Direct Fire Heaters 

Hybrid Trucks 

B20 Biodiesel 

Combined Diesel 

Powered Heating System

and Auto Engine 

Start/Stop System 

Battery Diesel Hybrid 

Switching Locomotive 

Plug-In Unit 

B20 Biodiesel 

B20 Biodiesel 

Convert Natural Gas 

Pneumatic Controls to 

Annual GHG Emissions Reductions (106 ton CO2 eq./year) 2.4 15.0 7.6 24.5 30.8 2.3 1.1 0.4 3.5 1.5 0.7 Annual Energy Use Reduction (1012 BTU /year) 27 185 94 300 -370 29 14 4 -42 -18 1 Unit GHG Emissions Reductions (10-3 lb CO2 eq./ton-mile) 11 66 34 130 29 2.0 1.0 0.3 3.0 5.0 3.4 Unit Energy Use Reduction (BTU /ton-mile) 60 409 207 804 -176 12 6 2 -18 -31 3 Annualized Cost ($106/year) 570 3000 390 2430 3300 140 180 91 380 180 1.7 Annual Energy Cost Saving ($106/year) 900 3400 1740 5600 0 530 260 230 0 0 13 Net Saving ($106/year) 330 440 1350 3190 -3300 390 70 135 -380 -180 12 Net Savings per Unit of GHG Emissions Reductions ($/ton CO2 eq.) 

138 29 178 130 -108 167 65 364 -109 -120 18 

Net Savings per Unit of Energy Use Reduction ($/106 BTU) 

12 2.3 14 10.6 N/A b 13.5 5.2 38 N/A b N/A b 9.6 

Simple Pay- back period (years) N/A c 3.2 0.6 2.1 N/A d 2.1 5.5 0.8 N/A d N/A d 0.3 

a These assessments are based on the assumptions that these best practices reach their potential maximum market shares in 2025. b This practice has no energy use reduction due to an increase in energy use, and it has no net saving due to high annualized cost and nc There is no pay-back period for this best practice because there is no initial capital cost to uses. d There is no pay-back period for this best practice because there is no net saving. 
107

There is substantial variability among these 13 best practices regarding their net cost 

savings. Ten best practices produce net cost savings. Many of these have very high capital 

costs, annual costs, or both but these are offset by even greater savings, typically for reduced fuel 

cost savings. For three of the best practices, the net savings are negative. Thus, these practices 

do not pay for themselves. These three practices, based on the use of B20 biodiesel, have a net 

increase in total costs because the fuel cost is higher than that for petroleum diesel, based on 

current typical experience. 

There is substantial variability among these 13 best practices regarding their 

cost-effectiveness. The top three most cost-effective best practices are: plug-in units for the 

rail mode; direct-fired heaters for the truck mode; and combined diesel powered heating system 

and auto engine start/stop system for the rail mode. The least cost-effective best practices are 

B20 biodiesel for the truck, rail and water modes. The variability of fuel prices, capital costs and 

operation and maintenance costs strongly impacts the accuracy of the cost-effectiveness results. 

Volatile fuel prices could cause the practices that do not correctly pay for themselves to produce 

net cost savings. For example, if diesel fuel price is reduced by 12%, the net savings of 

auxiliary power units for the truck mode would be negative. Changes in capital cost, such as an 

expected decrease over time in the capital cost for hybrid trucks, could cause practices that do 

not yet pay for themselves to produce a net cost saving. If petroleum oil prices continue to 

increase, it is possible that biodiesel fuel price might become lower than petroleum diesel fuel 

price, in which case the use of B20 Biodiesel might produce a net cost saving. 

There is substantial variability among these 13 best practices regarding their simple 

pay-back periods. Eight best practices have simple pay-back periods of less than 5 years, and 

five among these seven practices have simple payback periods of a year or less. One best 

practice produces a net savings but has no pay-back period because there is no initial capital cost. 

There is no pay-back period for the three best practices because they do not produce a net saving. 

From a national policy perspective, consideration of the potential magnitude of 

reductions is important. From an individual owner or operator perspective, consideration of 

cost savings and cost effectiveness may tend to be more important. 

9.6.3 Intermodal Substitutions 

Intermodal shifts, such as from modes with high emissions per unit of freight transport 

(e.g., airplanes and trucks), to lower-emission modes, such as rail and sea-going ships, are 

attractive options for GHG emissions reductions, if feasible. The typical unit GHG emissions 

per unit of freight activity of each of these modes range from 0.06 to 2.16 lb CO2 per ton-mile, as 

illustrated in Figure 9-3. For example, the GHG emissions per ton-mile for rail are only 8 

percent of those for trucks, implying a maximum GHG emissions reduction of 92 percent if rail 
108

0.0

0.5

1.0

1.5

2.0

2.5

Truck Rail Air Water Pipeline

Figure 9- 3. Estimated GHG Emissions per Unit of Freight Transport of Each Mode 

could substitute completely for trucking. The GHG emissions per ton-mile for ships are only 

17 percent those of trucks, implying a maximum GHG emissions reduction of 83 percent if ships 

could substitute completely for trucking. 

There have been some recent evaluations of the effectiveness of inter-modal shifts as a 

GHG emissions reduction strategy. A Germany mail-order company reduced its annual CO2

emissions by 40% from 1993 to 1999, based on substituting sea-going ships for truck and air 

transport.126 For example, five percent of its consignments were transported by ship instead of 

truck in its Turkish market, and led to a savings of 0.16 tonnes of CO2 per tonne of merchandise. 

Furthermore, eight percent of air freight in the Hong Kong market was shifted to a combined 

sea-air transportation sequence, leading to reductions of 2.8 tonnes of CO2 per tonne of 

merchandise. A Canadian study estimated that a shift of one-third of truck freight to rail could 

decrease emissions by 19% between 2000 and 2010 in Ontario. This analysis was based on 

both vehicle and fuel cycle emissions.127 

However, whether freight can be shifted from trucks to rail or ships may depend on a 

number of factors. These factors include distance, availability of infrastructure (e.g., port 

terminals, rail/truck intermodal facilities), size of the cargo, schedule, durability of the cargo, 

relative costs,127 and the need for new logistics systems.126 For example, some amount of truck 

activities, such as pick up and delivery, are likely to be needed even if most of the ton-miles 

involved rail,. According to one estimate, seven percent of the freight ton-miles require GHG Emissions per Unit of Freight Trans

port (lb CO2 e

q. per ton-mile)
109

shipment by truck for pick up and delivery, with the balance shipped by rail.128 For this 

scenario, the rail-truck inter-modal shift would reduce GHG emissions by approximately 85 

percent, instead of the maximum possible 92 percent. Of course, the actual reductions are also 

affected by implementation of best practices for GHG reduction in both the truck and rail modes, 

which can lead to a differing percentage difference for the inter-modal shift. 

Thus, whether one mode of shipping can be a substitute for another depends on 

site-specific characteristics, and system-level intermodal analysis will be needed. 
110

10.0. CONCLUSIONS AND RECOMMENDATIONS 

The purpose of the guidebook is to identify and characterize potential best practices for 

reducing energy use and refrigerant use in freight transportation, which could lead to reductions 

in GHG emissions. Some best practices for which sufficient information is available are 

assessed quantitatively based on several criteria. There is a lack of quantitative data for most of 

the identified best practices, and these best practices are assessed qualitatively. This research 

represents a “first step” in identifying best practices in the freight industry. Qualitative 

assessments are accompanied by preliminary estimates of overall reductions based on various 

assumptions that are detailed in the appendices. This Chapter presents key conclusions and 

recommendations. 

10.1 Conclusions 

If current trends continue, the increase in modal GHG emissions could range from 15 to 

67 percent from 2003 to 2025, depending on the mode. If best practices are aggressively 

implemented, it is possible to achieve a net decrease in total GHG emissions and energy use, 

even if intermodal substitutions (e.g., truck to rail) do not occur. Even larger percentage 

reductions are possible if intermodal shifts are encouraged, particularly away from trucking and 

air and toward rail and water-borne modes. Of course, as best practices are implemented that 

reduce GHG emissions from each mode, the relative reduction associated with inter-modal shifts 

will also change. 

Many best practices are in early stages of development or commercialization. Therefore, 

there is limited cost data upon which to assess these best practices quantitatively. For thirteen 

best practices for which adequate cost data are available for quantitative assessment, the modal 

reductions in GHG emissions and energy use were highly variable. The normalized cost 

savings per unit of GHG emissions reduction was also highly variable. Ten of these practices 

offer net cost savings, while three of them have net cost increases. There is also substantial 

variability regarding the simple pay-back periods of best practices that have net savings. 

However, five of them have simple payback periods of a year or less. 

Governments and individual owners or operators should carefully identify and compare 

their options. From a national policy perspective, some best practices, such as direct fired 

heaters and B20 biodiesel for trucks, offer greater potential for large magnitudes in reduction of 

total GHG emissions, but may not be as cost-effective. There may be targeted opportunities for 

the Federal government to promote research and development of such options in order to reduce 
111

their costs or to provide other incentives for their adoption. Of course, consideration must be 

given to co-benefits or adverse consequences of any given policy option. From an individual 

owner or operator perspective, consideration of cost savings and cost effectiveness may tend to 

be more important. Some best practices may be a “no regrets” proposition, in that the owner or 

operator can realize a net cost savings. 

This guidebook makes no recommendations about the use of specific strategies as best 

practices. Typically information regarding many best practices is incomplete and does not 

enable situation-specific assessment and comparison. While it is clear that many best practices 

will not be considered by potential adopters until adequate cost data is available upon which to 

estimate costs reliably, at this time insufficient data are available to characterize costs reliably for 

most of the best practices identified here. Potential best practices assessed qualitatively can be 

assessed quantitatively after sufficient information is available for quantitative assessment. 

Potential best practices assessed quantitatively can be further analyzed taking into account the 

variability or uncertainty of key assumptions, such as market penetration rates, fuel prices, 

discount rates, capital costs, and operation and maintenance costs. 

10.2 Recommendations for Future Research Needs 

To further inform decisions regarding adoption of suitable best practices, the following 

work is recommended: 

(1) Update information

Many technologies are currently in the developmental stage and there is not 

sufficient information available yet for quantitative assessments. There is a critical 

need for future work to better characterize the costs data. Information given here 

may be updated as new information becomes available. 

(2) Revise or Develop Cost Estimates as New Data Become Available

In this work, costs could be assessed for only 13 best practices. However, 

potential adopters of best practices need cost data for all of the possible best practices 

that could be applied to their situation. Thus, there is a critical need for more cost 

information. Ongoing work is recommended to obtain or develop cost estimates for 

best practices for which costs are not reported here, as well as to update cost 

estimates reported here as new data become available. 

(3) Evaluate key assumptions and other factors that influence the selection of best 

practices

The impact of variations of key assumptions, such as market penetration rates, 

fuel prices, capital costs, and operation and maintenance costs, may be assessed via 
112

sensitivity analysis. It is also important to understand the impacts of other factors, 

such as: the applicability and practical barriers of new technologies; policies and 

regulations; governmental incentives, such as financial, data, and analytical support, 

and costs and benefits seen by operators versus overall national reductions. 

(4) Develop tools to support decision making regarding best practices

i. Develop a web-based decision tree: 

A decision tree is helpful when faced with a complex multistage decision 

problem. Thus, a decision tree is a useful tool to help inform decision making 

regarding the choice of best practices. A decision tree involves a hierarchical 

cascade of questions to guide responsible and target parties toward promising 

best practices appropriate to their situations. Decision trees include choice 

nodes, uncertainty nodes, and valuation. Choice nodes represent discrete 

actions that can be taken by a decision maker. Uncertainty nodes represent the 

range of possible outcomes associated with a particular decision option. 

Decisions can be made in a sequence, leading to a complete design for vehicle 

or modal technology and operations. The value of each alternative strategy 

can be quantified in a multiple attribute framework, including monetized 

attributes (e.g., cost savings) and non-monetized attributes (e.g., percentage 

reduction in energy use, emissions). The decision tree may be implemented in 

an interactive web-based format and could be publicly accessible. 

ii. Develop a decision tool

Conditions of a specific responsible or target party, such as local fuel 

costs are critical considerations in choosing a best practice to adopt. 

Therefore, there is a critical need to develop a decision support that will allow 

such parties to compare multiple best practices on the basis of representative 

and relevant important assumptions. For such a tool, a user should be able to 

enter his or her own data and assumptions. 
113

REFERENCES

1. USEPA (2005), “Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2003, 

Final Version,” EPA 430-R-05-003, U.S. Environmental Protection Agency, Washington, 

DC, April. 

2. FHWA (2005), “Assessing the Effects of Freight Movement on Air Quality at the National 

and Regional Level, Final Report,” Prepared by ICF Consulting for Federal Highway 

Administration, Washington, DC, April, http://www.fhwa.dot.gov/environment/freightaq/

(Accessed 09/10/05). 

3. BTS (2005), “National Transportation Statistics 2005,” Bureau of Transportation Statistics 

of U.S. Department of Transportation, Washington, DC, June, 

http://www.bts.gov/publications/national_transportation_statistics/pdf/entire.pdf (Accessed 

09/10/05). 

4. EIA (2006), “Annual Energy Outlook 2006,” DOE/EIA-0383(2006), Energy Information 

Administration, Washington, DC, February, 

http://www.eia.doe.gov/oiaf/aeo/pdf/0383(2006).pdf (Accessed 06/10/06). 

5. USEPA (2005), “SmartWay Transport Partnership,” U.S. Environmental Protection Agency, 

Ann Arbor, MI, http://www.epa.gov/smartway/ (Accessed 08/31/05). 

6. Grant, M., K. See, and D. Downing (1998), “Transportation and Global Climate Change: 

a Review and Analysis of the Literature, Final Report,” DOT-T-97-03, Prepared by Hagler 

Bailly, Inc. for Federal Highway Administration, Washington, DC, June. 

7. FHWA (1999), “Greenhouse Gas Control Strategies: A Review of "Before-and-After" 

Studies,” Prepared by Energy and Environmental Analysis, Inc and Cambridge Systematics 

for Federal Highway Administration, Washington, DC, November 12. 

8. USEPA (2005), “Clean Automotive Technology,” U.S. Environmental Protection Agency, 

Ann Arbor, MI, http://www.epa.gov/OMSWWW/technology/ (Accessed 09/10/05). 
114

9. EIA (2000), “Analysis of the Climate Change Technology Initiative: Fiscal Year 2001,” 

SR/OIAF/2000-01, Energy Information Administration, Washington, DC, April, pp 68-79. 

10. BSR (2005), “Clean Cargo: Sustainability in Freight Transport,” Business for Social 

Responsibility, San Francisco, CA, http://www.bsr.org/CSRResources/WGO/CC-GF/

(Accessed 09/10/05). 

11. Ang-Olson, J. and W. Schroeer (2002), “Energy Efficiency Strategies for Freight Trucking: 

Potential Impact on Fuel Use and Greenhouse Gas Emissions,” Transportation Research 

Record: Journal of the Transportation Research Board, 2002(1815):11-18. 

12. Bedsworth, L.W. (2004), “Climate Control: Global Warming Solutions for California 

Cars,” Union of Concerned Scientists, April, 

http://www.ucsusa.org/global_warming/solutions/climate-control-clean-vehicles-greenhous

e-gas-in-california.html (Accessed 09/10/05). 

13. USEPA (2002), “Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2000,” 

EPA 430-R-02-003, U.S. Environmental Protection Agency, Washington, D.C., April 15. 

14. Nishioka S. (2000), “Report for Plenary Discussion on Domestic Best Practices Addressing 

Climate Change in G8 Countries.” G8 Environmental Futures Forum 2000 on Domestic 

Best Practices Addressing Climate Change, Prepared for Environment Agency of Japan, 

Tokyo, Japan, http://www.env.go.jp/earth/g8_2000/forum/g8bp/index.html (Accessed 

08/20/05). 

15. BTS (2005), “Freight Transportation,” Bureau of Transportation Statistics, Washington, DC, 

http://www.bts.gov/programs/freight_transportation/ (Accessed 08/20/05). 

16. AASHTO (2005) Freight Transportation Network, The American Association of State 

Highway and Transportation Officials (AASHTO), Washington, DC, 

http://freight.transportation.org/ (Accessed 08/20/05). 

17. FHWA (2003), “FHWA Vehicle Types,” Federal Highway Administration, Washington, DC, 
115

October 14, http://www.fhwa.dot.gov/policy/ohpi/vehclass.htm (Accessed 10/05/06). 

18. US Census Bureau (2004), “2002 Economic Census: Vehicle Inventory and Use Survey-- 

Geographic Area Series-- United States: 2002,” EC02TV-US, U.S. Census Bureau, 

Washington, DC, December 2, http://www.census.gov/prod/ec02/ec02tv-us.pdf (Accessed 

10/05/06). 

19. National Academy of Sciences (2000), “Review of the U.S. Department of Energy's Heavy 

Vehicle Technologies Program,” National Academy Press, Washington, D.C., 

http://www.nap.edu/catalog/9989.html (Accessed 10/05/06). 

20. Gaines, L., A. Vyas, and J.L. Anderson (2006), " Estimation of Fuel Use by Idling 

Commercial Trucks," Paper No. 06-2567, Prepared by Argonne National Laboratory, 

Argonne, IL for the 85th Annual Meeting of the Transportation Research Board, 

Washington, DC, January 22-26. 

21. Berkeley (2004), “Municipal Code: Title 14 Vehicles and Traffic: Chapter 14.56 

Movement of Heavy Vehicles and Equipment: Section 14.56.080 Definitions and truck 

classification,” City of Berkeley, California, 

http://www.ci.berkeley.ca.us/bmc/berkeley_municipal_code/title_14/56/080.html

(Accessed 10/5/06). 

22. AAR (2005), “Railroads: The Vital Link to North America’s Economic Future: 

Overviews of U.S. Freight Railroads,” Association of American Railroads, Washington, DC, 

February, http://www.aar.org/PubCommon/Documents/AboutTheIndustry/Overview.pdf

(Accessed 09/14/05). 

 

23. BTS (2002), “The Commodity Flow Survey,” Bureau of Transportation Statistics of U.S. 

Department of Transportation, Washington, DC, 

http://www.bts.gov/programs/commodity_flow_survey/methods_and_limitations/html/scop

e_and_survey_methods.html (Accessed 8/20/05). 

24. US Census Bureau (2004), “North American Industry Classification System --Revisions for 

2002,” December 29, http://www.census.gov/epcd/naics02 (Accessed 10/30/05). 
116

25. Lutsey, N., C.-J. Brodrick, D. Sperling, and C. Oglesby (2004), “Heavy-Duty Truck Idling 

Characteristics: Results from a Nationwide Truck Survey,” Transportation Research 

Record: Journal of the Transportation Research Board, 2004(1880):29-38. 

26. Thomas L. (2004), "Truck Stop Electrification as a Long-Haul Idling Alternative," Prepared 

by Perrot ANTARES Group Inc., Landover, MD for the New York State Energy Research 

and Development Authority, and presented at the 2004 Annual Meeting of the 

Transportation Research Board, Washington, DC, January 13, 

http://www.epa.gov/smartway/documents/dewitt-study.pdf (Accessed 09/14/05). 

27. Stodolsky, F., L. Gaines, and A. Vyas (2000), “Analysis of Technology Options to Reduce 

the Fuel Consumption of Idling Trucks,” ANL/ESD-43, Prepared by Energy Systems 

Division of Argonne National Laboratory for U.S. Department of Energy, Washington, DC, 

June, http://www.transportation.anl.gov/pdfs/TA/15.pdf (Accessed 03/05/06). 

28. Chris Lindsey and Jeff Kim (2005), “Summary of Operations: Fleet Demonstrations of 

Shorepower Truck Electrified Parking on the I-87 Northway: Final Report,” NYSERDA 

Agreement Number 7209, Prepared by Antares Group Inc. and Shurepower l.L.C. for The 

New York State Energy Research and Development Authority, Albany, NY, December, 

http://www.nyserda.org/publications/I87TSEDemonstrationReportDec05.pdf (Accessed 

03/05/06). 

29. ANTARES (2005), “Summary of Operations: Truck Stop Electrification Facilities on the 

New York State Thruway: Final Report,” NYSERDA Agreement Number 6282, Prepared 

by Antares Group Inc. for The New York State Energy Research and Development 

Authority, Albany, NY, January, 

http://www.nyserda.org/publications/I-90TSEDemonstrationReportJan05.pdf (Accessed 

03/05/06). 

30. The Computerworld Honors Program (2005), “Advanced Travel Center (Truck Stop) 

Electrification (ATE) System: 2005 Computerworld Honors Case Study,” 

http://www.cwheroes.org/laureates/transportation/idleaire.pdf (Accessed 10/15/05). 

31. California ARB (2004), “Staff Report: Initial Statement of Reasons for Proposed 

Rulemaking: Airborne Toxic Control Measure to Limit Diesel-Fueled Commercial Motor 
117

Vehicle Idling,” California Air Resources Board, Sacramento, CA, July 22, 

http://www.arb.ca.gov/regact/idling/isor.pdf (Accessed 04/05/06). 

32. Vyas, A., C. Saricks and F. Stodosky (2002), “The Potential Effect of Future 

Energy-Efficiency and Emissions-Improving Technologies on Fuel Consumption of Heavy 

Trucks,” ANL/ESD/02-4/, Argonne National laboratory, Argonne, IL, August, 

http://www.ipd.anl.gov/anlpubs/2003/03/45815.pdf (Accessed 10/05/05). 

33. California ARB (2004), “Draft Technology and Cost Assessment for Proposed Regulations 

to Reduce Vehicle Climate Change Emissions Pursuant to Assembly Bill 1493,” California 

Air Resources Board, Sacramento, CA, April 1, 

http://www.arb.ca.gov/cc/042004workshop/final-draft-4-17-04.pdf (Accessed 01/05/06). 

34. Anderson, S.O., W. Atkinson, and J.A. Baker (2002), “Existing and Alternate Vehicle Air 

Conditioning (A/C) Systems,” Non-CO2 Greenhouse Gases: Scientific Understanding, 

Control Options and Policy Aspects, Millpress: Rotterdam, Netherlands. 

35. EU (2003), “Consultation Paper: How to Considerably Reduce Greenhouse Gas 

Emissions Due to Mobile Air Conditioners,” Directorate-General Environment of European 

Commission, Brussels, 4 February. 

36. California ARB (2004), “Mobile Air Conditioning Systems-Direct Emissions Technology 

Assessment,” California Air Resources Board, Sacramento, CA, August 6, 

http://www.arb.ca.gov/cc/factsheets/august_tsd/hfc_direct_august.pdf (Accessed 06/05/06). 

37. California ARB (2004), “Mobile Air Conditioning Systems-Indirect Emissions,” California 

Air Resources Board, Sacramento, CA, August 6, 

http://www.arb.ca.gov/cc/factsheets/august_tsd/hfc_indirect_august.pdf (Accessed 

06/05/06). 

38. NESCCAF (2004), “Interim Report Reducing Greenhouse Gas Emissions from Light-Duty 

Vehicles,” Northeast States Center for a Clean Air Future, March, 

http://www.clf.org/uploadedFiles/CLF/Programs/Clean_Energy_&_Climate_Change/Clima

te_Protection/Clean_Cars/NESCCAF%20white%20paper.pdf (Accessed 04/05/06). 
118

39. Wood, R. M., Bauer, S. X. S (2003),” Simple and Low-Cost Aerodynamic Drag Reduction 

Devices for Tractor-Trailer Trucks,” 2003-01-3377, Society of Automotive Engineers 

Technical Paper Series, November, http://www.solusinc.com/pdf/2003-01-3377.pdf

(Accessed 08/01/06). 

40. Saltzman, E.J. and Meyer, R.R. Jr. (1999), “A Reassessment of Heavy-Duty Truck 

Aerodynamic Design Features and Priorities,” NASA/TP-1999-206574, National 

Aeronautics and Space Administration and Dryden Flight Research Center, Edwards, 

California, June, http://www.nasa.gov/centers/dryden/pdf/88628main_H-2283.pdf

(Accessed 08/02/06). 

41. Englar, R,J. (2004), “Pneumatic Heavy Vehicle Aerodynamic Drag Reduction, Safety 

Enhancement, and Performance Improvement,” The Aerodynamics of Heavy Vehicles: 

Trucks, Buses, and Trains, Lecture Notes in Applied and Computational Mechanics,, 

Springer, Heidelberg, Germany, pp. 277-302. 

42. John Toon (2001), “Flying Low-Drag Trucks: Aerodynamic Concepts and Controls for 

Aircraft Will Cut Fuel Use and Improve Control in Trucks,” Georgia Tech Research 

Institute, February 16, http://gtresearchnews.gatech.edu/reshor/rh-win01/trucks.html

(Accessed 03/05/06). 

43. LLNL (2003), “May 2003 Working Group Meeting on Heavy Vehicle Aerodynamic Drag: 

Presentations and Summary of Comments and Conclusions,” Lawrence Livermore 

National Laboratory, California, May 29-30, 

http://www.llnl.gov/tid/lof/documents/pdf/245808.pdf (Accessed 06/15/06). 

44. Coon, J.D. and K.D. Visser (2004), “Drag Reduction of a Tractor-Trailer Using Planar Boat 

Tail Plates,” The Aerodynamics of Heavy Vehicles: Trucks, Buses, and Trains, Lecture 

Notes in Applied and Computational Mechanics, Springer, Heidelberg, Germany, pp. 

249-265. 

45. USEPA (2004), “EPA Technical Bulletins: A Glance at Clean Freight Strategies: 

Automatic Tire Inflation Systems,” EPA 420-F-04-010, U.S. Environmental Protection 

Agency, Ann Arbor, MI, February, 

http://www.epa.gov/otaq/smartway/documents/tireinflate.pdf (Accessed 10/05/06). 
119

46. USEPA (2004), “EPA Technical Bulletins: A Glance at Clean Freight Strategies: Single 

Wide-Based Tires,” EPA 420-F-04-004, U.S. Environmental Protection Agency, Ann Arbor, 

MI, February, http://www.epa.gov/otaq/smartway/documents/supersingles.pdf (Accessed 

10/05/06). 

47. Michelin Corporate, “Michelin and the Environment,” 

http://www.michelin.com/corporate/front/templates/affich.jsp?codeRubrique=88&lang=EN

&codePage=PAG_COMP_PNEU (Accessed 12/16/06). 

48. Englar, R.J. (2000), “Development of Pneumatic Aerodynamic Devices to Improve the 

Performance, Economics, and Safety of Heavy Vehicles,” SAE/TPS-2000-01-2208, 

Prepared by Georgia Tech Research Institute for Government/Industry Meeting, 

Washington, DC, June 19, 

http://www.osti.gov/energycitations/servlets/purl/770965-K88tPq/native/770965.pdf

(Accessed 10/01/06). 

49. Langer, T. (2004), “Energy Saving Through Increased Fuel Economy for Heavy-duty 

Trucks,” Prepared by American Council for an Energy-Efficient Economy for the National 

Commission on Energy Policy, February 11, 

http://report.energycommission.org/newfiles/Final_Report/III_Efficiency/III.4.a%20-%20H

eavy-Duty%20Trucks.pdf (Accessed 10/20/05). 

50. USEPA (2004), “EPA Technical Bulletins: A Glance at Clean Freight Strategies: Weight 

Reduction,” EPA 420-F-04-005, U.S. Environmental Protection Agency, Ann Arbor, MI, 

February, http://www.epa.gov/otaq/smartway/documents/weightreduction.pdf (Accessed 

10/05/06). 

51. Saricks, C., A.D. Vyas, F. Stodolsky, and J.D. Maples (2003), “Fuel Consumption of 

Heavy-Duty Trucks: Potential Effects of Future Technologies for Improving Energy 

Efficiency and Emissions,” Transportation Research Record: Journal of the 

Transportation Research Board, 2003, 1842:9-19. 

52. USEPA (2004), “EPA Technical Bulletins: A Glance at Clean Freight Strategies: 

Low-Viscosity Lubricants,” EPA 420-F-04-006, U.S. Environmental Protection Agency, 

Ann Arbor, MI, February, 

http://www.epa.gov/otaq/smartway/documents/lowviscositylubes.pdf (Accessed 10/05/06). 
120

53. Bradley, R. (2000), “Technology Roadmap for the 21st Century Truck Program: A 

Government-Industry Research Partnership,” 21CT-001, Office of Heavy Vehicles 

Technologies of U.S. Department of Energy, Oak Ridge, Tennessee , December, 

http://www.osti.gov/fcvt/21stcenturytruck.pdf (Accessed 01/15/06). 

54. DieselNet (2006), “Volvo unveils 2007 truck engines,” February 14, 

http://www.dieselnet.com/news/2006/02volvo.php (Accessed 11/27/06). 

55. CAF, “Advances in Diesel Engine Technology,” Clean Air Fleet, 

http://www.cleanairfleets.org/advances.html (Accessed 11/26/06). 

56. USDOE (2006), “FY 2005 Progress Report for Advanced Combustion Engine 

Technologies,” Energy Efficiency and Renewable Energy Office of FreedomCAR and 

Vehicle Technologies, U.S. Department of Energy, Washington, D.C., January, 

http://www.eere.energy.gov/vehiclesandfuels/pdfs/adv_engine_2005/2005_advanced_engin

e.pdf (Accessed 09/09/06). 

57. USDOT (2004), “FreedomCAR and Vehicle Technologies Program: Success Story – 

DOE’s “More Electric Truck” Could Revolutionize the Heavy-duty Trucking Industry,” 

Energy Efficiency and Renewable Energy Office of FreedomCAR and Vehicle 

Technologies, U.S. Department of Energy, Washington, D.C., October, 

http://www1.eere.energy.gov/vehiclesandfuels/pdfs/success/more_electric_truck_04.pdf

(Accessed 10/5/06). 

58. USEPA (2004), “EPA Technical Bulletins: A Glance at Clean Freight Strategies: 

Drivers Training,” EPA 420-F-04-008, U.S. Environmental Protection Agency, Ann Arbor, 

MI, February, http://www.epa.gov/otaq/smartway/documents/drivertraining.pdf (Accessed 

10/05/06). 

59. Natural Resource Canada, “FleetSmart Profiles: Highway Trucking-Woodstock 

Transport,” http://oee.nrcan.gc.ca/transportation/business/documents/ (Accessed 9/12/05). 

60. Gaines, L., F. Stodolsky, and R. Cuenca (1998), “Life-Cycle Analysis for Heavy Vehicles,” 

Argonne National Laboratory, Prepared for Air & Waste Management Association Annual 
121

Meeting, San Diego, California, June, http://www.transportation.anl.gov/pdfs/TA/102.pdf

(Accessed 12/15/06). 

61. Pang, S.H. and H.C. Frey (2006), “Life Cycle Inventory Energy Use and Emissions for 

Biodiesel versus Petroleum Diesel Fuels,” North Carolina State University, presented at the 

16th CRC On-Road Vehicle Emissions Workshop, San Diego, California, March 28-30. 

62. Strong, C., C. Erickson and D. Shukla (2004), “Evaluation of Biodiesel Fuel: Literature 

Review,” FHWA/MT-04-001/8117-20, Prepared by Western Transportation Institute of 

Montana State University at Bozeman for Montana Department of Transportation, Helena, 

MT, January, http://www.coe.montana.edu/wti/wti/pdf/425244_Lit_Review.pdf (Accessed 

02/10/06). 

63. NBB (2004), “Report of the Biodiesel Workgroup,” Prepared by National Biodiesel Board 

for California’s Energy Commission, Sacramento, CA, October 12, 

http://www.energy.ca.gov/afvs/documents/2004-10-12_BIODIESEL_GROUP.PDF

(Accessed 02/13/06). 

64. Tyson, K.S., J. Bozell, R. Wallace, E. Petersen, and L. Moens (2004); “Biomass Oil 

Analysis: Research Needs and Recommendations,” NREL/TP-510-34796, National 

Renewable Energy Laboratory, Golden, Colorado, June 20, 

http://www.nrel.gov/docs/fy04osti/34796.pdf (Accessed 02/16/06). 

65. EIA (2006), “Assumptions to the Annual Energy Outlook 2006: Transportation Demand 

Module,” DOE/EIA-0554(2006), Energy Information Administration, Washington, DC, 

March, http://www.eia.doe.gov/oiaf/aeo/assumption/pdf/transportation.pdf (Accessed 

03/11/06). 

66. Sheehan, J., V. Camobreco, J. Duffield, M. Graboski, and H. Shapouri (1998), “Life Cycle 

Inventory of Biodiesel and Petroleum Diesel for Use in an Urban Bus: Final Report,” 

NREL/SR-580-24089, Prepared by the National Renewable Energy Laboratory for U.S. 

Department of Agriculture and U.S. Department of Energy, Washington, DC, May. 

67. Gaines, L. (2004), “Heavy Vehicle Idling: How to Reduce its Impacts,” Presented at 

Clean Heavy-Duty Vehicle Conference, Sponsored by WestStart and the U.S. Army 
122

National Automotive Center, Rancho Mirage, CA, February 25–27, 

http://www.transportation.anl.gov/pdfs/TA/296.pdf (Accessed 11/01/05). 

68. USEPA (2004), “Case study: Chicago Locomotive Idle Reduction,” EPA420-R-04-003, 

U.S. Environmental Protection Agency, Washington, DC, March. 

69. Montañez, J. and M. Mahler (2005), “Reducing Idling Locomotives Emissions,” North 

Carolina Department of Environment and Natural Resources, 

http://daq.state.nc.us/planning/reducing_idling_locomotive_emissions.ppt (Accessed 

12/17/06). 

70. USEPA (2006), “SmartWay Transport Partnership ― Idling Reduction: Alternatives,” 

U.S. Environmental Protection Agency, Washington, D.C., August 11th, 

http://www.epa.gov/smartway/idlingalternatives.htm#Technology (Accessed 12/27/06). 

71. Queen, R.B., “Green $ave$ Green: The Green Goat Hybrid Locomotive,” Mew 

Technologies Committee, Locomotive Maintenance Officers Association, 

http://www.railpower.com/dl/greensavesgreen.pdf (Accessed 12/22/06). 

72. Gaines, L. (2004), “Locomotive Idling,” Presented at National Idling Reduction Planning 

Conference, Sponsored by U.S. Department of Energy, U.S. Department of Transportation, 

U.S. Environmental Protection Agency, and the New York State Energy Research and 

Development Authority, Albany, NY, May 17-19, 

http://www.transportation.anl.gov/pdfs/RR/312.pdf (Accessed 11/01/05). 

73. Punwani, S.K. (2002), “Progress in Railroad Freight Car Engineering,” Rail Transportation 

2002, RTD-Vol. 22, American Society of Mechanical Engineering, New York, NY, pp. 

63-72. 

74. Canadian Pacific Railway (2006), “CANADIAN PACIFIC RAILWAY Ingenuity: 2006 

corporate profile + fact book,” 

http://www8.cpr.ca/cms/NR/rdonlyres/ecsepstmuey5gw2wzladjfb424vrtub5u3hdqzhotq26

wq6znvb2bf36got6u22udtst7qghxnj6gucq6ckleu57xbh/2006_Corporate_Profile_and_Fact

_Book_d6_07_09_06.pdf (Accessed 12/10/06). 
123

75. Judge, D. (2000), “Lubrication optimizes wheel-rail interface - railroad maintenance,” 

February, http://findarticles.com/p/articles/mi_m0BFW/is_2_96/ai_60008643 (Accessed 

12/18/06). 

76. Judge, T. (2004), “A Smo-o-o-th Ride,” Railway Age, 205(12):35-37, December. 

77. Environment Canada (2005), “Locomotive Emissions Monitoring Program 2004 

(Environmental protections series: EPS 2/TS/19),” Transportation Division, Clean Air 

Directorate, Environment Canada, Ottawa, Ontario, December, 

http://www.railcan.ca/documents/publications/1118/2006_04_12_LemReport2004_en.pdf

(Accessed 02/05/06). 

78. Fritz, S.G. (2004), “Evaluation of Biodiesel Fuel in an EMD GP38-2 Locomotive,” 

NREL/SR-510-33416, Prepared by Southwest Research Institute for National Renewable 

Energy Laboratory, Golden, CO, April. 

79. Dunn, R. (2003), “Biodiesel as a Locomotive Fuel in Canada,” TP 14106E, Prepared for 

Transportation Development Centre (TDC), Montreal, Quebec, Canada, and Energy 

Research and Development (PERD) of Natural Resources Canada, May, 

http://www.tc.gc.ca/tdc/publication/pdf/14100/14106e.pdf (Accessed 02/05/06). 

80. King, D. and I.A. Waitz (2005), “Assessment of the Effects of Operational Procedures and 

Derated Thrust on American Airlines B777 Emissions from London’s Heathrow and 

Gatwick Airports,” Report No. PARTNER-COE-2005-001, Partnership for Air 

Transportation Noise and Emissions Reduction, Sponsored by the Federal Aviation 

Administration, the National Aeronautics and Space Administration, and Transport Canada, 

July 21. http://web.mit.edu/aeroastro/partner/reports/drate-rpt.pdf (Accessed 8/12/07). 

81. IPCC (1999), Aviation and the Global Atmosphere: A Special Report of IPCC Working 

Groups I and III, Intergovernmental Panel on Climate Change, Cambridge University Press, 

Cambridge, UK. 

82. Reneaux, J. (2004), “Overview on Drag Reduction Technologies for Civil Transport 

Aircraft,” European Congress on Computational Methods in Applied Sciences and 

Engineering, ECCOMAS 2004, Jyväskylä, July24 – 28, 2004, 
124

http://www.onera.fr/daap-en/drag-reduction/drag-reduction-technologies-for-civil-transport

-aircraft-reneaux.pdf (Accessed 02/25/06). 

83. Joslin, R.D. (1998), “Aircraft Laminar Flow Control,” Annual Review of Fluid Mechanics, 

30:1-29, January, http://arjournals.annualreviews.org/doi/full/10.1146/annurev.fluid.30.1.1. 

(Accessed 12/25/06). 

84. Thomas, R.H., M.M. Choudhari, and R.D. Joslin (2002), “Flow and Noise Control: 

Review Assessment of Future Directions,” NASA/TM-2002-211631, National Aeronautics 

and Space Administration, Langley Research Center, Hampton, Virginia, April 2002, 

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20020045525_2002078986.pdf

(Accessed 12/25/06). 

85. Bajnath, R., B. Beasley, and M. Cavanaugh (2004), “Laminar Flow,” AOE 4124, Virginia 

Polytechnic Institute and State University, March 29, 

http://www.aoe.vt.edu/~mason/Mason_f/LaminarFlowS04.ppt (Accessed 12/25/06). 

86. EUROCONTROL (2007), “Overall Concept and Architecture Activity (OCA): Glossary,” 

the EUROCONTROL Organisation, Brussels, Belgium. 

http://www.eurocontrol.int/oca/public/site_preferences/display_glossary_list.html

(Accessed 8/14/07). 

87. JPDO (2007a), “Concept of Operations for the Next Generation Air Transport System: 

Version 2.0,” Joint Planning and Development Office, Washington, DC, June 13. 

http://www.jpdo.gov/library/NextGen_v2.0.pdf (Accessed 8/14/07). 

88. JPDO (2007b), “Making the NextGen Vision a Reality: 2006 Progress Report to the Next 

Generation Air Transportation System Integrated Plan,” Next Generation Air 

Transportation System (NextGen), Joint Planning and Development Office, Washington, 

DC. http://www.jpdo.aero/pdf/2006_Progress_Report.pdf (Accessed 8/11/07). 

89. Iglesias, A. (2001), “Reducing Fuel Burn through Improved Operational Measures,” 

Prepared by Emissions Operational-Measures Working Group, CAEP WG-4, Presented at 

Colloquium on Environmental Aspects of Aviation, Montreal, 9 to 11 April 2001. 

http://www.icao.int/icao/en/env/clq01/iglesias.ppt#34 (Accessed 6/11/07). 
125

90. FAA (2007), “Reduced Vertical Separation Minimum,” Federal Aviation Administration, 

U.S. Department of Transportation, Washington, DC, Updated June 19 

http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/enroute/rvsm/

(Accessed 8/11/07). 

91. Waitz, I.A. (2007), “Project 18: Reduced Vertical Separation Minimums,” 

http://web.mit.edu/aeroastro/partner/projects/project18.html (Accessed 8/12/07). 

92. Clarke, J.-P., et al (2006), “Development, Design, and Flight Test Evaluation of a 

Continuous Descent Approach Procedure for Nighttime Operation at Louisville 

International Airport,” Report No. PARTNER-COE-2005-02, Partnership for Air 

Transportation Noise and Emissions Reduction, Sponsored by the Federal Aviation 

Administration, the National Aeronautics and Space Administration, and Transport Canada, 

January 9. http://web.mit.edu/aeroastro/partner/reports/cda_rpt.pdf (Accessed 8/12/07). 

93. ICAO (2005), “Reducing Aviation Emissions: the Manufacturers’ Perspective,” 

International Civil Aviation Organization, December 7, 

www.icao.int/icao/en/aviation_day/2005/ICCAIA.pdf (Accessed 03/01/06). 

94. Emadi, A., M. Ehsani, and J.M. Miller (2004), Vehicle Electric Power Systems: Land, Sea, 

Air, and Space Vehicles, Marcel Dekker, Inc., New York, NY, pp. 214-217. 

95. EVI, “Sherpa Electric Vehicle,” Electric Vehicle International, Anderson, Indiana, 

http://www.evi-usa.com/pdf/sherpa_brochure011.pdf (Accessed 01/25/06). 

96. Winkelman, S. and G. Dierkers (2003), “Reducing the Impacts of Transportation on Global 

Warming,” Transportation Research Record: Journal of the Transportation Research 

Board, 2003(1842):83-90. 

97. ICF (2005), “Estimating Transportation-Related Greenhouse Gas Emissions and Energy 

Use in New York State,” Prepared by ICF Consulting for U.S. Department of 

Transportation, Washington, DC, March 18, http://climate.dot.gov/docs/nys.pdf (Accessed 

04/17/06). 

98. Peeters, P.M., J. Middel and A. Hoolhorst (2005), “Fuel Efficiency of Commercial Aircraft: 

An Overview of Historical and Future Trends,” NLR-CR-2005-669, National Aerospace 
126

Laboratory NLR, German, November, 

http://www.transportenvironment.org/docs/Publications/2005pubs/2005-12_nlr_aviation_fu

el_efficiency.pdf (Accessed 03/14/06). 

99. Mecham, Michael (2006), “GEnx Development Emphasizes Composites, Combustor 

Technology,” Aviation Week, the McGraw-Hill Companies, Inc, April 16, 

http://www.aviationweek.com/aw/generic/story_channel.jsp?channel=comm&id=news/aw0

41706p1.xml (Accessed 04/14/07). 

100. GE Aviation (2005), “Driving GE Ecomagination with the Low-Emission GEnx Jet 

Engine,” July 20, http://www.geae.com/aboutgeae/presscenter/genx/genx_20050720.html

(Accessed 03/14/06). 

101. Aviation Partners, Inc., “Blended Winglets: Investment Benefits,” 

http://www.aviationpartners.com/bw_invest.html (Accessed 12/06/06). 

102. Rakow, J.F. and Pettinger, A.M. (2006), “Failure Analysis of Composite Structures in 

Aircraft Accidents,” ISASI 2006 Annual Air Safety Seminar, Cancun, Mexico, September 

11-14, http://www.exponent.com/about/docs/ISASI2006_paper.pdf (Accessed 03/15/06). 

103. CADDET (2002), “Energy-saving ship uses off-centre propeller,” Centre for Analysis and 

Dissemination of Demonstrated Energy Technologies (CADDET), International Energy 

Agency, July, http://www.caddet.org/infostore/display.php?id=2928 (Accessed 10/18/05). 

104. CADDET (2002), “Propeller Boss Cap with Fins (PBCF) allows more efficient ship 

propulsion,” Centre for Analysis and Dissemination of Demonstrated Energy Technologies 

(CADDET), International Energy Agency, June, 

http://www.caddet.org/infostore/display.php?id=1763 (Accessed 10/18/05). 

105. CADDET (2002), “Grim Vane Wheel installed on rudder horn reduces ship's energy 

consumption,” Centre for Analysis and Dissemination of Demonstrated Energy 

Technologies (CADDET), International Energy Agency, July, 

http://www.caddet.org/infostore/display.php?id=3056 (Accessed 10/18/05). 

106. Yokota, K (2006), “My view on environmental technologies,” Mitsui O.S.K. Lines, Ltd., 
127

http://www.mol.co.jp/csr-e/environment/management/technologies/index.shtml (Accessed 

12/25/06). 

107. IMO (2000) “Study of Greenhouse Gas Emissions from Ships,” Issue no. 2 – 31, 

International Maritime Organization, March, 

http://unfccc.int/files/methods_and_science/emissions_from_intl_transport/application/pdf/

imoghgmain.pdf (Accessed 12/25/05). 

108. EIA (2005), “Electricity InfoCard 2004,” DOE/EIA-X058, U.S. Energy Infromation 

Administration, Washington, DC, January, 

http://www.eia.doe.gov/neic/brochure/elecinfocard.html (Accessed 05/14/06). 

109. Entec (2005), “Service Contract on Ship Emissions: Assignment, Abatement and 

Market-based Instruments: Task 2a – Shore-Side Electricity: Final Report,” Prepared by 

Entec UK Limited, Cheshire, England, UK for Directorate General Environment of 

European Commission, August, 

http://europa.eu.int/comm/environment/air/pdf/task2_shoreside.pdf (Accessed 05/14/06). 

110. USEPA (2003), “Final Regulatory Support Document: Control of Emissions from New 

Marine Compression-Ignition Engines at or Above 30 Liters per Cylinder,” 

EPA420-R-03-004, United States Environmental Protection Agency, Washington, D.C., 

January, http://www.epa.gov/otaq/regs/nonroad/marine/ci/r03004.pdf (Accessed 12/26/06). 

111. USEPA (1999), “In-Use Marine Diesel Fuel,” EPA 420-R-99-027, U.S. Environmental 

Protection Agency, Washington, D.C., August. 

112. Corbett, J.J. and H.W. Koehler (2003), “Updated emissions from ocean shipping,” Journal 

of Geophysical Research, 108(D20): 4650-4666. 

113. von Wedel, R (1999), “Technical Handbook for Marine Biodiesel: Second Edition,” 

Subcontract: ACG-7-16688-01, under Prime Contract: DE-AC36-83CH10093, 

Prepared by CytoCulture International, Inc. for the National Renewable Energy Laboratory 

of U.S. Department of Energy, April 22, 

http://www.cytoculture.com/Biodiesel%20Handbook.htm (Accessed 07/14/06). 
128

114. EIA (2005), “Short-term Energy Outlook,” Energy Information Administration, Washington, 

DC, October. 

115. EIA (2006), “April 2006 Petroleum Marketing Monthly,” U.S. Energy Information 

Administration, March 31, 

http://www.eia.doe.gov/oil_gas/petroleum/data_publications/petroleum_marketing_monthl

y/pmm.html (Accessed 04/14/06). 

116. Shore, T., T. Plenys, and D. Bailey (2004), “Feasibility of Providing Shore-Based Electrical 

Power to Ships while Docked: Environmental Perspective,” Prepared by Bluewater 

Network, Coalition for Clean Air, and Natural Resources Defense Council, and presented at 

California Air Resources Board Public Consultation Meeting, Sacramento, CA, November 

9, http://www.bluewaternetwork.org/reports/cv/ARBShoreside.pdf (Accessed 06/10/06). 

117. USEPA (2004), “Lessons Learned From Natural Gas STAR Partners: Convert Gas 

Pneumatic Controls to Instrument Air,” EPA-430-B-04-003, U.S. Environmental Protection 

Agency, Washington, DC, February, 

http://www.epa.gov/gasstar/pdf/lessons/ll_instrument_air.pdf (Accessed 11/14/05). 

118. USEPA (2003), “Lessons Learned From Natural Gas STAR Partners: Options for 

Reducing Methane Emissions from Pneumatic Devices in The Natural Gas Industry,” 

EPA-430-B-03-004, U.S. Environmental Protection Agency, Washington, DC, July, 

http://www.epa.gov/gasstar/pdf/lessons/ll_pneumatics.pdf (Accessed 11/15/05). 

119. USEPA (2004), “Replacing High-Bleed Pneumatic Devices: Lessons Learned From 

Natural Gas STAR,” Prepared by Bill Barrett Corporation, Evergreen Resources Inc, 

Southern Gas Association and U.S. Environmental Protection Agency’s Natural Gas STAR 

Program for Small and Medium Sized Producer Technology Transfer Workshop, Colorado, 

June 29, 

http://www.epa.gov/gasstar/workshops/colorado-june29/2-devices.ppt#295,1,Replacing 

High-Bleed Pneumatic Device (Accessed 11/01/05). 

120. USEPA (2003), “Using Hot Taps for In Service Pipeline Connections: Lessons Learned 

from Natural Gas STAR Partners,” EPA430-B-03-010, U.S. Environmental Protection 

Agency, Washington, DC, December. 
129

121. Venugopal, S. (2003), “The Effective Management of Methane Emissions from Natural 

Gas Pipelines,” Proceedings of the 6th International Conference on Greenhouse Gas 

Control Technologies, Vol. II, Elsevier Limited, Kidlington, Oxford, UK, pp. 1293-1298. 

122. USEPA (2003), “Lessons Learned From Natural Gas STAR Partners: Using Hot Taps for 

in Service Pipeline Connections,” EPA430-B-03-010, U.S. Environmental Protection 

Agency, Washington, DC, December, http://www.epa.gov/gasstar/pdf/lessons/ll_hottaps.pdf

(Accessed 11/14/05). 

123. TransCanada (2000), “TransCanada’s 2000,” Calgary, Alberta, Canada, reported to the 

Climate Change Voluntary Challenge and Registry, Canada, September, 

http://www.ghgregistries.ca/registry/out/C0135-TC00VCR-PDF.PDF (Accessed 01/12/06). 

124. Pigging Products & Services Association (2006), “About Pigs,” 

http://www.ppsa-online.com/about-pigs.php (Accessed 11/12/06). 

125. UP (2004), “Locomotive Idle Reduction: Technology Issues,” Prepared by Union Pacific 

Railroad Company, presented at National Idling Reduction Planning Conference, 

Sponsored by U.S. Department of Energy, U.S. Department of Transportation, U.S. 

Environmental Protection Agency, and the New York State Energy Research and 

Development Authority, Albany, NY, May 17-19, 

http://www.transportation.anl.gov/pdfs/RR/312.pdf (Accessed 11/01/05). 

126. OECD (2002), “Report on the OECD Conference Environmentally Sustainable Transport 

(EST): Futures, Strategies and Best Practice,” ENV/EPOC/WPNEP/T(2001)8/FINAL, 

Prepared by the OECD’s Working Group on Transport under the Working Party on 

Pollution Prevention and Control of the Environmental Policy Committee, February 14, 

http://www.olis.oecd.org/olis/2001doc.nsf/43bb6130e5e86e5fc12569fa005d004c/5ebb4a5e

203badc5c1256b5a003f3dd7/$FILE/JT00120803.PDF (Accessed 09/01/06). 

127. Sally Walker, S., R. Hilburn, and R. Colman (1999), “Genuine Progress Index Approach to 

Analyzing Reduction of Greenhouse Gas Emissions in the Nova Scotia Freight Transport 

Sector,” GPIAtlantic, May, http://www.gpiatlantic.org/pdf/freight/freight.pdf (Accessed 

08/01/06). 
130

128. Caceres, J. and D. Richards (2002). “Secure, Efficient and Sustainable Trade under 

NAFTA,” Proceedings of the 37th Annual Conference of Canadian Transportation 

Research Forum, Newfoundland, Canada, pp. 501-515. 

129. Gaines, L. (2004), “Truck Idling: Implications and Solutions,” Argonne National 

Laboratory, presented at Alternatives to Truck Engine Idling Workshop, Des Moines, Iowa, 

June 22-23, Sponsored by the Iowa Energy Center and the Iowa State University Center for 

Transportation Research and Education, http://www.ctre.iastate.edu/pubs/truck_idling/

(Access 11/25/05). 

130. Van den Berg, A.J. (1996), “Truckstop Electrification: Reducing CO2 Emissions from 

Mobile Sources While They are Stationary,” Energy Conversion and Management, 

37(6-8):879-884, August. 

131. Frey, H.C. and K. Kim (2005), “Operational Evaluation of Emissions and Fuel Use of B20 

Versus Diesel Fueled Dump Trucks,” HWY 2004-18, Prepared by Department of Civil 

Engineering at North Carolina State University for North Carolina Department of 

Transportation, Raleigh, NC, September 30. 

132. EERE, “Alternative Fuels: General Table of Fuel Properties,” Office of Energy Efficiency 

and Renewable Energy, U.S. Department of Energy, Washington, DC, 

http://www.eere.energy.gov/afdc/altfuel/fuel_properties.html (Accessed 11/25/05). 

133. EIA (2006), “Annual Energy Review 2005,” DOE/EIA-0384(2005), Energy Information 

Administration, Department of Energy, Washington, D.C., July 27, 

http://www.eia.doe.gov/emeu/aer/pdf/aer.pdf (Accessed 1/17/06). 

134. EPA (2006), “EPA SmartWay Transport Partnership – Idle Reduction Technologies,” U.S. 

Environmental Protection Agency, August 11th, 

http://www.epa.gov/otaq/smartway/idlingtechnologies.htm (Accessed 10/13/06). 

135. Cheryl Bynum (2007), Presented in Talking Freight – Strategies to Reduce Greenhouse Gas 

Emissions from Freight Transportation Seminar, Federal Highway Administration, 
131

Department of Transportation, Washington, D.C., January 17, 

http://www.ops.fhwa.dot.gov/freight/fpd/talking_freight.htm (Accessed 1/17/07). 

136. ATRI (2006), “Idle Reduction Technology: Fleet Preferences Survey,” Prepared by the 

American Transportation Research Institute, Alexandria, VA for New York State Energy 

Research and Development Authority, Albany, NY, February, 

http://www.westcoastdiesel.org/files/sector-trucking/fleet-preferences-survey.pdf (Accessed 

1/18/07). 

137. OPIS (2005), “Fuel Ethanol & Biodiesel Report: Volume 2, Issue 18,” Oil Price 

Information Service, Rockville, MD, May 2, 

http://www.opisnet.com/news/sample/ethanol.pdf (Accessed 01/14/06). 

138. BNSF (2004), “Two-tech Fuel Cost Taming,” Railway Age, 205(7):26, July. 

139. Gaines, L. (2005), “Heavy Vehicle Idling Reduction,” Presented at NASEO Annual Meeting, 

New York, NY, September 13, 

http://www.naseo.org/events/annual/2005/presentations/Gaines.pdf (Accessed 1/20/07). 

140. EIA (2006), “Electric Power Annual 2005,” DOE/EIA-0348(2005), Energy Information 

Administration, Department of Energy, Washington, D.C., November, 

http://www.eia.doe.gov/cneaf/electricity/epa/epa.pdf (Accessed 1/20/07). 

141. MARAD (2005), “U.S. Waterborne Foreign Trade Statistics: U.S. Waterborne 

Commerce,” Maritime Administration of US Department of Transportation, Washington, 

DC, April 7, http://www.marad.dot.gov/Marad_Statistics/WBC_1983_2003.pdf (Accessed 

6/23/06). 

142. BTS (2005), “National Transportation Statistics 2005: Water Transport Profile”, Bureau of 

Transportation Statistics of U.S. Department of Transportation, Washington, DC, April, 

http://www.bts.gov/publications/national_transportation_statistics/2005/html/table_water_t

ransport_profile.html (Accessed 6/23/06). 

143. UNCTAD (2005), “Review of Maritime Transport, 2005,” UNCTAD/RMT/2005, United 

Nations Conference on Trade and Development, Geneva, Switzerland, July, 

http://www.unctad.org/en/docs/rmt2005_en.pdf (Accessed 6/23/06). 
132

144. Corbett, J. J. (2004), “Marine Transportation and Energy Use,” Encyclopedia of Energy, 3: 

pp. 745-758, Elsevier Inc., San Diego, CA. 

145. EIA, “Energy Calculator - Common Units and Conversions,” U.S. Energy Information 

Administration, Washington, DC, 

http://www.eia.doe.gov/kids/energyfacts/science/energy_calculator.html#natgascalc

(Accessed 01/14/06). 

146. HEI (2002), “Research Directions to Improve Estimates of Human Exposure and Risk from 

Diesel Exhaust: A Special Report of the Institute’s Diesel Epidemiology Working Group,” 

Health Effects Institute, Boston MA, April, 

http://www.healtheffects.org/Pubs/DieselSpecialReport02.pdf (Accessed 11/24/05). 

147. EIA (2005), “Weekly Petroleum Status Report Glossary,” Energy Information 

Administration, Washington, DC, May, 

http://www.eia.doe.gov/pub/oil_gas/petroleum/data_publications/weekly_petroleum_status_r

eport/current/pdf/glossary.pdf (Accessed 12/18/05). 

148. Denton, J.E. (2004), “Used Oil in Bunker Fuel: A Review of Potential Human Health 

Implication,” California Environmental Protection Agency, December, 

http://www.oehha.ca.gov/risk/pdf/UsedOilInBunkerFuel.pdf (Accessed 01/11/06). 

149. RTI International (2003), “Generic Verification Protocol for Determination of Emissions 

Reductions Obtained by Use of Alternative or Reformulated Liquid Fuels, Fuel Additives, 

Fuel Emulsions, and Lubricants for Highway and Nonroad Use Diesel Engines,” 

CR829434-01-1, Prepared by RTI International for U. S. Environmental Protection Agency, 

September, http://www.epa.gov/etv/pdfs/vp/05_vp_fuel.pdf (Accessed 11/24/05). 

150. EIA “Energy Glossary,” Energy Information Administration, Washington, DC, 

http://www.eia.doe.gov/glossary/glossary_main_page.htm (Accessed 11/13/05). 

151. NIBS, “Whole Building Design Guide: Standards Library: Federal and Military 

Specifications and Standards,” National Institute of Building Sciences, Washington, DC, 
133

http://www.wbdg.org/ccb/index.php (Accessed 01/05/06). 

 

152. US Naval Academy (2005), “Naval Applications of Chemistry: Fuels and Lubricants,” 

Chemistry Department, U. S. Naval Academy, Annapolis, MD, August 18, 2005, 

http://www.chemistry.usna.edu/navapps/pdf/fuels_01.pdf (Accessed 12/18/05). 

153. ARAC (1998), “Fuel Properties - Effect on Aircraft and Infrastructure: Final Report,” 

Prepared by The Fuels Properties Task Group for the Fuel Tank Harmonization Working 

Group of the FAA Aviation Rulemaking Advisory Committee, Revised on July 15, 

http://www.fire.tc.faa.gov/pdf/TG67.pdf (Accessed 04/27/07). 

154. NREL (2005), “Advanced Vehicles & Fuel Research: Advanced Fuels Properties 

Database,” National Renewable Energy Laboratory, Golden, CO, 

http://www.nrel.gov/vehiclesandfuels/fuels_database.html (Accessed 12/18/05). 

155. Henderson, S. (2000), “Assessment of Net Emissions of Greenhouse Gases from 

Ethanol-Gasoline Blends in Southern Ontario,” R-2000-1, Prepared by Levelton Engineering 

Ltd. for Agriculture and Agri-Food Canada, Ottawa, Canada January, 

http://www.tc.gc.ca/programmes/environnement/changementclimatique/docs/ETOH-FNL-RP

TAug30-1999.doc (Accessed 01/12/06). 

156. AGA (2005), “Natural Gas Glossary,” American Gas Association, Washington, DC, 

http://www.aga.org/Content/NavigationMenu/About_Natural_Gas/Natural_Gas_Glossary/

(Accessed 12/18/05). 

157. Tse, L. (2004), “Natural Gas Properties,” Vision Engineer Ltd., May 28, 

http://www.visionengineer.com/env/alt_ng_prop.php (Accessed 01/14/06). 

158. EIA (2006), “Refiner Petroleum Product Prices by Sales Type: US Area,” U.S. Energy 

Information Administration, Washington, DC, January 5, 

http://tonto.eia.doe.gov/dnav/pet/pet_pri_refoth_dcu_nus_m.htm (Accessed 01/12/06). 

159. EIA (2006), “Residual Fuel Oil Prices by Sales Type: US Area,” U.S. Energy Information 

Administration, Washington, DC, January 5, 
134

http://tonto.eia.doe.gov/dnav/pet/pet_pri_resid_dcu_nus_m.htm (Accessed 01/12/06). 
135

APPENDIX A. DETAILS OF INPUT DATA, ASSUMPTIONS, AND ESTIMATION 

RESULTS FOR TRUCK MODE BEST PRACTICES 

This appendix is additional descriptive information for the best practices in Chapter 4, 

including the standardized reporting tables, if their corresponding best practices can be assessed 

quantitatively, or the simplified summary tables, if their corresponding best practices are 

assessed qualitatively. For those assessed quantitatively, the methods for the estimation of data 

in the standardized reporting tables are also described. 

Appendix A.1 Best Practice 1-1: Off-Board Truck Stop Electrification 

This best practice is assessed quantitatively. Table A-1 summarizes the assessment 

results. This table is in the format of the standardized reporting table for quantitative results. 

The basis of the quantitative estimates is explained.

A. Estimate of total number of vehicles or devices: 

(a) Assumption: i. Total number of trucks with sleeper cab is equal to the number of 

trucks having conventional cab with sleeper plus the number of 

trucks having cab over engine with sleeper. 

ii. Total truck number in 2002 is equal to total truck number in 

2003. 

iii. Annual per-truck energy use in 2025 is the same as annual 

per-truck energy use in 2003. 

(b) Calculation: i. The 2002 Vehicle Inventory and Use Survey reported that 

568,600 trucks had conventional cab with sleeper, and 109,000 

trucks had cab over engine with sleeper.18 Thus, there were 

677,600 trucks with sleeper cab in 2003. 

(568,600 trucks)+ (109,000 trucks) = 677,600 trucks

ii. Since per-truck energy use is the same and modal energy use are 

estimated to grow by 67% from 2003 to 2025,4 total truck 

number increases by 67% from 2003 to 2025. 

 677,600 trucks × (1+ 67%) =1,131,500 trucks
136

Table A-1. Standardized Reporting Table for Best Practice 1-1, Off-Board Truck Stop 

Electrification.a

Characteristics of the Practice Description 

Practice Name Off-Board Truck Stop Electrification 

Mode Type Truck 

Subgroup Anti-Idling 

Responsible Parties 1, 2, 5, 13, 20, 21, 22

Target Parties 1, 2, 6, 8

Target GHGs CO2

Strategy Type Technology 

Practice Goals 

Goal is to have all trucks with sleeper 

cabs participate. The reductions in 

modal GHG emissions and energy use 

in 2025 would be 0.33% (2.4 ×106

 tons 

of CO2 eq.) and 0.31% (27.3 ×1012

Btu), respectively. 

Developmental Status C 

Practice Summary This practice enables truck drivers to 

switch off their base engines by 

connecting to a service module, which 

includes heating, air conditioning and 

electricity, at a truck stop. 

Emissions, Energy Use, and Refrigerant Use Unit Value 

Annual Transport Activity for the Mode (ATAM) 109 ton-miles/year 2,098 

Annual Transport Activity to Which a Practice Is 

Applicable (ATAP) 109

 ton-miles/year 453 

Annual GHG Emissions Reductions(AGR) 106 ton CO2 eq./year 2.4 

Annual Energy Use Reduction (AER) 1012 BTU /year 27.3 

Annual Refrigerant Use Reduction (ARR) lbs/year N/A 

Unit GHG Emissions Reductions (UGER) 10-3 lb CO2

eq./ton-mile 11 

Unit Energy Use Reduction (UER) BTU /ton-mile 60 

Unit Refrigerant Use Reduction (URR) lbs/ton-mile N/A 

Practice Costs 

Capital Cost ® 106 USD ($) N/A 

Discount Rate ® % 10% 

Technical Lifetime of Technology (L) years N/A 

Fixed Charge Factor (a) year-1 N/A 

Annual O & M Cost (AOM) $106 /year N/A 

Annualized Cost (AC) $106 /year 570

Annual Energy Cost Saving (AECS) $106 /year 900 

Annual Refrigerant Cost Saving (ARCS) $106 /year N/A 

Net Savings (NS) $106 /year 330 

Net Savings per Unit of GHG Emissions Reductions 

(NSGR) $/ton CO2 eq. 140 

Net Savings per Unit of Energy Use Reduction (NSER) $/106 BTU 12 

Net Savings per Unit of Refrigerant Use Reduction (NSRR) $/lb N/A 

Simple Payback Period (SPP) years N/Ab

a

 These assessments are based on the assumptions that these best practices reach their potential 
137

maximum market shares in 2025. 

b

 There is no pay-back period for this best practice because there is no initial capital cost to uses. 

(d) Results: There will be 1,131,500 trucks with sleeper cab in 2025. 

B. Estimate of annual transport activity for the mode: 

(a) Assumption: The growth rate of total transport activity is the same as the growth 

rate of energy use for the truck mode. 

(b) 2003 Results: The estimated total transport activity for the truck mode in the U.S. 

in 2003 is 1,256 ×109 ton-miles.3 

(c) 2025 Results: Since total energy use for the truck mode is estimated to grow by 

67% from 2003 to 2025,4 the estimated total transport activity for 

the truck mode in the U.S. in 2025 will be 2,098 ×109 ton-miles. 

C. Estimate of annual transport activity to which a practice is applicable: 

 (a) Assumption: The ratio of annual transport activity of trucks with sleeper cab to 

annual transport activity of all trucks is proportional to the ratio of 

energy use for trucks with sleeper cab to energy use for all trucks. 

(b) Calculation: The ratio of energy use for trucks with sleeper cab to energy use 

for all trucks is 21.6% (1.125×1015 BTU vs. 5.21×1015 BTU).3 

(c) Results: Since the ratio is 21.6%, the estimated total transport activity for 

the truck mode in the U.S. in 2025 will be 453 ×109

 ton-miles. 

D. Estimate of annual GHG emissions reductions: 

 (a) Assumption: i. Total GHG emissions reductions are that GHG emissions 

reductions due to energy use reduction minus GHG emissions 

due to electricity use for operating this practice at truck stops. 

ii. Approximately 20% of trucks are idled at truck stops.129

iii. On an annual basis an average truck accumulates about 1,830 
138

hours of parking idle,130 and one hour idle of a truck consumes 

0.85 gallon of diesel fuel.27 

(b) Calculation: i. Truck idle fuel use is 0.85 gal/hr, which is equal to 117,887 

BTU/hr because that the estimated heating value of petroleum 

diesel is 138,690 BTU/gallon.131-132 

ii. Total idle fuel use for trucks with sleeper cab in 2003 is 

estimated to be 1.46×108 (106 BTU) per year. 

 

1.46 10 ( ) 10 BTU

gallon

138,698 BTU

hr

0.85 gallon

trucks

hrs 677,600 trucks 1,830

8 6 = ×

















× × ×

iii. GHG emissions coefficient for diesel fuel is 0.0808 tons CO2

eq. per 106 BTU.1

iv. Total GHG emissions reductions due to fuel use reduction are 

estimated to be 2.36×106 tons CO2 eq. in 2003. 

 

( )

2.36 10 tons CO eq.

10 BTU

0.0808 tons CO eq. 1.46 10 10 BTU 20%

2

6

6

8 6 2

= ×

× × ×

v. Total energy output for IdleAire is 18,000 BTU/hr because that 

A/C or heater energy output average is 17,500 BTU/hr and 

other accessory consumes approximately 500 BTU/hr of 

energy. 

vi. GHG emissions coefficient for electricity is 0.0007 tons CO2

eq. per kWh.108 

vii. Total GHG emissions due to electricity use are estimated to be 

0.92×106 tons CO2 eq. in 2003. 

20% 0.92 10 tons CO eq.

kWh

0.0007 tons CO eq.

3412 BTU

kWh

hr

18000 BTU

trucks

hrs 677,600 trucks 1,830

2

6

2

× = ×















 × × × ×

viii. The estimated annual GHG emissions reductions are estimated 

to be 1.44×106

 tons CO2 eq. in 2003. 
139

 ( ) 2.36 10 0.92 10 tons CO eq. 1.44 10 tons CO eq. 2

6

2

6 6 × − × = ×

(c) Results: Since GHG emissions for the truck mode is estimated to grow by 

67%, which is explained in Section 1.2, the estimated 2025 annual 

GHG emissions reductions are 2.41×106

 tons CO2 eq. 

E. Estimate of annual energy use reduction: 

 (a) Assumption: i. Total energy use reduction is that energy use reduction minuses 

energy for producing electricity for operating this practice. 

ii. Approximately 20% of truck idling is at truck stops.129

iii. On an annual basis an average truck accumulates about 1,830 

hours of parking idle,130 and one hour idle consume 0.85 gallon 

of diesel fuel.27 

(b) Calculation: i. Truck idle fuel use is 0.85 gal/hr, which is equal to 117,887 

BTU/hr because that the estimated heating value of petroleum 

diesel is 138,690 BTU/gallon.131-132 

ii. Hourly electricity needed for producing electricity in order to 

operate this practice is 18,000 BTU/hr, including 17,500 BTU/hr 

for the average for operating A/C or heater and 500 BTU/hr for 

operating other accessory. 

iii. Since the ratio of primary energy input to electricity output is 

estimated to be 2.89 based on total electricity generated and total 

primary energy consumed in the U.S. in 2005,133 primary energy 

needed for producing electricity in order to operate this practice 

is 52,000 BTU/hr. 

iii. Since only 20% of trucks idle at truck stops, the suitable 

locations for this practice, the percentage of energy reduction for 

adopting this practice is estimated to be 11.2%. 

 20% 11.2%

117887

117887 52000× = 

 



 −

iv. Total energy use for trucks with sleeper cab at idle in 2003 is 
140

estimated to be 1.46×108 (106 BTU) per year. 

 

1.46 10 ( ) 10 BTU

gallon

138,698 BTU

hr

0.85 gallon

trucks

hrs 677,600 trucks 1,830

8 6 = ×

















× × ×

v. The estimated annual energy use reduction in 2003 is 1.63×107

(106 BTU). 

 1.46 10 (10 BTU) 10.6% 1.63 10 (10 BTU) 8 6 7 6 × × = ×

(c) Results: Since total energy use for the truck mode is estimated to grow by 

67%,4

 the estimated annual energy use reduction in 2025 is 

2.73×107 (106 BTU). 

F. Estimate of unit GHG emissions reductions: 

ton mile

0.011 lb CO eq.

ton

2,000 lbs . 453 billion ton miles

2.41 million tons CO2 eq 2

− =















× 















−

G. Estimate of unit energy use reduction: 

( )

ton mile

60.3 BTU . 453 billion ton miles2.73 10 10 BTU 7 6

− = 















−

×

H. Estimate of capital cost 

 (Not available because of no initial cost for this practice) 

I. Estimate of annual O & M cost

 (Not available) 

J. Estimate of annualized cost: 

(a) Assumption: The price for hourly service of this practice, which is provided by 

IdleAire, is the average of its individual driver’s price and its 

contract price. 

(b) Calculation: i. The price for individual driver is $1.5/hr and the contract price is 

$1.25/hr. Thus, the average price is estimated to be $1.375/hr.5
141

ii. The estimated annualized cost in 2003 is $341×106. 

 6 $341 10

hr

$1.375 20%

trucks

hrs 677,600 trucks 1,830  = ×



 





× × ×

(c) Results: Since total truck number is estimated to grow by 67%, which is 

explained in Appendix A.1.A, the estimated annualized cost in 

2025 is $569 ×106

. 

K. Estimate of energy cost reduction: 

(a) Assumption: Diesel fuel price in 2025 is the same as the price of the second 

season of 2005, which is $2.56/gallon ( = $18.5/106 BTU).114 

(b) Calculation: The estimated energy cost reduction in 2003 is $540 ×106

. 

( ) 6

6

8 6 $540 10

10 BTU

$18.5 1.46×10 10 BTU × 20% × = ×

(c) Results: Since total energy use is estimated to grow by 67% from 2003 to 

2025, which is explained in Appendix A.1.A, the estimated energy 

cost reduction in 2025 is $902 ×106. 

L. Estimate of net savings: 

6 6 6 $902×10 − $569×10 = $333×10

M. Estimate of net savings per unit of GHG emissions reductions: 

ton CO eq.

$138.2

2.41 10 tons CO eq.

$333 10

2 2

6

6

= ×

×

N. Estimate of net savings per unit of energy use reduction: 

10 BTU

$12.2

27.3 10 BTU

$333 10

12 6

6

= ×

×

O. Estimate of simple payback period: 

 (Not available because there is no initial capital cost for this practice). 
142

Appendix A.2 Best Practice 1-2: Truck-Board Truck Stop Electrification 

This best practice is assessed qualitatively. Table A-2 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table A-2. Simplified Summary Table for Best Practice 1-2, Truck-Board Truck Stop 

Electrification

Attribute Description 

Practice Name Truck-board Truck Stop Electrification 

Mode Type Truck 

Subgroup Anti-Idling 

Responsible Parties 1, 2, 5, 6, 8, 11, 13, 20, 21, 22

Target Parties 1, 2,4, 6, 8

Target GHGs CO2

Strategy Type Technology 

Practice Goals 

Goal is to have all trucks with sleeper cabs participate. The reductions 

in modal GHG emissions and energy use in 2025 would be 0.39% and 

0.41%, respectively. 

Developmental Status C 

Practice Summary This system enables truck drivers to switch off their diesel engines by 

connecting parked trucks to electrical outlets (receptacles) for electric 

powered on-board HVAC systems at a truck stop. 

Potential Reductions in 

Modal GHG Emissions 

0.39% 

Potential Reduction in 

Modal Energy Use 

0.41% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information The operation charge for this system is $0.5~$1.00 per hour per truck 

Benefits and Drawbacks Using electricity consumes less energy and emits less GHG than using 

diesel fuel for truck base engine. Trucks cannot use this alternative 

unless they are parked at a truck stop with this type of electrification 

system. 
143

Appendix A.3 Best Practice 1-3: Auxiliary Power Units 

This best practice is assessed quantitatively. Table A-3 summarizes the assessment 

results. This table is in the format of the standardized reporting table for quantitative results. 

The basis of the quantitative estimates is explained.

A. Estimate of total number of vehicles or devices: 

Total number of vehicles is explained in Appendix A.1.A. 

B. Estimate of annual transport activity for the mode: 

Annual transport activity for the mode is explained in Appendix A.1.B. 

C. Estimate of annual transport activity to which a practice is applicable: 

Annual transport activity to which this practice is applicable is explained in Appendix 

A.1.C. 

D. Estimate of annual GHG emissions reductions: 

 (a) Assumption: i. Total GHG emissions reductions are due to energy use reduction. 

ii. On an annual basis an average truck accumulates about 1,830 

hours of parking idle,130 and one hour idle of a truck consumes 

0.85 gallon of diesel fuel.27 

iii. The fuel rate for APU use is estimated to be 0.2 gallon of diesel 

fuel per hour.134 

(b) Calculation: i. Idle fuel use is estimated to be 117,887 BTU/hr, explained in 

Appendix A.1. 
144

Table A-3. Standardized Reporting Table for Best Practice 1-3, Auxiliary Power Units.a

Characteristics of the Practice Description 

Practice Name Auxiliary Power Units 

Mode Type Truck 

Subgroup Anti-Idling 

Responsible Parties 1, 2, 5, 6, 8, 11

Target Parties 1, 2, 4, 6

Target GHGs CO2

Strategy Type Technology 

Practice Goals 

Goal is to have all trucks with sleeper 

cabs participate. The reductions in 

modal GHG emissions and energy use in 

2025 would be 20.8% (15.0 ×106

 tons of 

CO2 eq.) and 2.13% (185 ×1012 Btu), 

respectively. 

Developmental Status C 

Practice Summary APUs are mounted externally on the truck 

cabs or sleepers that provide heat and A/C 

for the sleeper, heat for engine, and power 

for auxiliaries. They can avoid the need 

for idling of the truck base engines 

Emissions, Energy Use, and Refrigerant Use Unit Value 

Annual Transport Activity for the Mode (ATAM) 109 ton-miles/year 2,098 

Annual Transport Activity to Which a Practice Is 

Applicable (ATAP) 109

 ton-miles/year 453 

Annual GHG Emissions Reductions(AGR) 106 ton CO2 eq./year 15.0 

Annual Energy Use Reduction (AER) 1012 BTU /year 185.0 

Annual Refrigerant Use Reduction (ARR) lbs/year N/A 

Unit GHG Emissions Reductions (UGER) 10-3 lb CO2 eq./ton-mile 66 

Unit Energy Use Reduction (UER) BTU /ton-mile 409 

Unit Refrigerant Use Reduction (URR) lbs/ton-mile N/A 

Practice Costs 

Capital Cost (C) 106 USD ($) 9,400 

Discount Rate (r) % 10% 

Technical Lifetime of Technology (L) years 5 

Fixed Charge Factor (a) year-1 0.264 

Annual O & M Cost (AOM) $106 /year 520 

Annualized Cost (AC) $106 /year 2,990

Annual Energy Cost Saving (AECS) $106 /year 3,430 

Annual Refrigerant Cost Saving (ARCS) $106 /year N/A 

Net Savings (NS) $106 /year 440 

Net Savings per Unit of GHG Emissions Reductions 

(NSGR) $/ton CO2 eq. 29 

Net Savings per Unit of Energy Use Reduction (NSER) $/106 BTU 2.3 

Net Savings per Unit of Refrigerant Use Reduction 

(NSRR) $/lb N/A 

Simple Payback Period (SPP) years 3.2 a

 These assessments are based on the assumptions that these best practices reach their potential 

maximum market shares in 2025. 
145

 ii. Total fuel use reduction for this practice in 2003 is estimated to 

be 1.11×108 (106 BTU) per year. 

 

1.11 10 ( ) 10 BTU

0.85

0.85 0.2

gallon

138,698 BTU

hr

0.85 gallon

trucks

hrs 677,600 trucks 1,830

8 6  = ×



 



 − ×

















× × ×

iii. GHG emissions coefficient for diesel fuel is 0.0808 tons CO2

eq. per 106 BTU.1

iv. Total GHG emissions reductions due to fuel use reduction are 

estimated to be 8.97×106

 tons CO2 eq. in 2002. 

 ( )

8.97 10 tons CO eq.

10 BTU

0.0808 tons CO eq. 1.11 10 10 BTU

2

6

6

2 8 6

= ×

× ×

(c) Results: Since GHG emissions for the truck mode is estimated to grow by 

67%, which is explained in Section 1.2, the estimated 2025 GHG 

emissions reductions are 14.98×106 tons CO2 eq.. 

E. Estimate of annual energy use reduction: 

i. Fuel use reduction for this practice in 2003 is estimated to be 1.11×108

 (106 BTU), 

explained in Appendix A.3.D. 

ii. Since energy use for the truck mode is estimated to grow by 67%,4

 the estimated 

annual energy use reduction in 2025 is 1.85×108 (106 BTU). 

F. Estimate of unit GHG emissions reductions: 

ton mile

0.066 lb CO eq.

ton

2,000 lbs . 453 billion ton miles

14.98 million tons CO2 eq 2

− =















× 















−
146

G. Estimate of unit energy use reduction: 

( )

ton mile

408.96 BTU . 453 billion ton miles

1.85 10 10 BTU 8 6

− = 















−

×

H. Estimate of capital cost 

i. The capital cost of an auxiliary power unit, which includes factory cost and installation 

cost, is estimated to be $8,279 per truck.31 Total capital costs of auxiliary power units 

for all trucks with sleeper cab in 2003 is estimated to be $5.6 ×109. 

9 9 677,600 trucks $4.8 10 $5.6 10

truck

$8,279

× = × = ×

ii. Since the truck mode is estimated to grow by 67%, total capital costs of auxiliary 

power units for all trucks with sleeper cab in 2025 is estimated to be $9.4 ×109

. 

I. Estimate of annual O & M cost

i. Annual maintenance cost of an auxiliary power unit per is estimated to be $460.51 

Total annual maintenance costs of auxiliary power units for all trucks with sleeper cab 

in 2003 is estimated to be $312 ×106. 

8 6 677,600 trucks $3.12 10 $312 10

truck

$460

× = × = ×

ii. Since total truck number is estimated to grow by 67%, which is explained in Appendix 

A.1.A, annual O & M costs of auxiliary power units for all trucks with sleeper cab in 

2025 is estimated to be $520 ×106

. 

J. Estimate of annualized cost: 

i. The life-time of auxiliary power units is estimated to be 5 years.31 

ii. Fixed charge factor is estimated to be 0.264. 

( )

( )

0.264

3.79

1

1 0.1

1

1

arg 5

1

= =

































+

=

∑i=

i

Fixed ch e factor a

iii. ( ) ( ) 9 $9.4 billion× 0.264 + $520 million = $2.99×10
147

K. Estimate of energy cost reduction: 

(a) Assumption: Diesel fuel price in 2025 is the same as the price of the second 

season of 2005, which is $2.56/gallon ( = $18.5/106 BTU).114 

(b) Calculation: The estimated energy cost reduction in 2003 is $2.05 ×109. 

( ) 9

6

8 6 $2.05 10

10 BTU

$18.5 1.11×10 10 BTU ×× = ×

(c) Results: Since total energy use for the truck mode is estimated to grow by 

67% from 2003 to 2025,4

 the estimated energy cost reduction in 

2025 is $3.43 ×109. 

L. Estimate of net savings: 

9 9 6 $3.43×10 − $2.99×10 = $438×10

M. M. Estimate of net savings per unit of GHG emissions reductions: 

ton CO eq.

$28.99

14.98 10 tons CO eq.

$438 10

2 2

6

6

= ×

×

N. Estimate of net savings per unit of energy use reduction: 

10 BTU

$2.34

185 10 BTU

$438 10

12 6

6

= ×

×

O. Estimate of simple payback period: 

( ) 3.22 years $3.43 10 $0.52 10

$9.4 10

9 9

9

= × − ×

×
148

Appendix A.4 Best Practice 1-4: Direct-Fired Heaters 

This best practice is assessed quantitatively. Table A-4 summarizes the assessment 

results. This table is in the format of the standardized reporting table for quantitative results. 

The basis of the quantitative estimates is explained. 

A. Estimate of total number of vehicles or devices: 

Total number of vehicles is explained in Appendix A.1.A. 

B. Estimate of annual transport activity for the mode: 

Annual transport activity for the mode is explained in Appendix A.1.B. 

C. Estimate of annual transport activity to which a practice is applicable: 

Annual transport activity to which this practice is applicable is explained in Appendix 

A.1.C. 

D. Estimate of annual GHG emissions reductions: 

 (a) Assumption: i. Total GHG emissions reductions are due to energy use reduction. 

ii. This practice is estimated to reduce fuel use for trucks with 

sleeper cab by 5%.135 

(b) Calculation: i. Total energy used for trucks with sleeper cab is estimated to be 

1.125×1015 BTU.3

 

ii. Total fuel use reduction for this practice in 2003 is estimated to 

be 5.63×1013 BTU per year. 

 1.125 10 BTU 5% 5.63 10 BTU 13

0

15 × × = ×

iii. GHG emissions coefficient for diesel fuel is 0.0808 tons CO2

eq. per 106

 BTU.1
149

Table A-4. Standardized Reporting Table for Best Practice 1-4, Direct-Fired Heaters.a

Characteristics of the Practice Description 

Practice Name Direct-Fired Heaters

Mode Type Truck 

Subgroup Anti-Idling 

Responsible Parties 1, 2, 5

Target Parties 1, 2, 4, 6

Target GHGs CO2

Strategy Type Technology 

Practice Goals 

Goal is to have all trucks with sleeper 

cabs participate. The reductions in 

modal GHG emissions and energy use in 

2025 would be 1.05% (7.6 ×106

 tons of 

CO2 eq.) and 1.08% (94 ×1012 Btu), 

respectively. 

Developmental Status C 

Practice Summary Direct-fired heaters can avoid the need for 

idling of truck base engines in cold 

weather. Heat is produced from diesel 

fuel combustion and transferred to a heat 

exchanger for sleeper cabs and engines. 

Emissions, Energy Use, and Refrigerant Use Unit Value 

Annual Transport Activity for the Mode (ATAM) 109 ton-miles/year 2,098 

Annual Transport Activity to Which a Practice Is 

Applicable (ATAP) 109

 ton-miles/year 453 

Annual GHG Emissions Reductions(AGR) 106 ton CO2 eq./year 7.6 

Annual Energy Use Reduction (AER) 1012 BTU /year 93.9 

Annual Refrigerant Use Reduction (ARR) lbs/year N/A 

Unit GHG Emissions Reductions (UGER) 10-3 lb CO2 eq./ton-mile 34 

Unit Energy Use Reduction (UER) BTU /ton-mile 207 

Unit Refrigerant Use Reduction (URR) lbs/ton-mile N/A 

Practice Costs 

Capital Cost (C) 106 USD ($) 996 

Discount Rate (r) % 10% 

Technical Lifetime of Technology (L) years 5 

Fixed Charge Factor (a) year-1 0.264 

Annual O & M Cost (AOM) $106 /year 125 

Annualized Cost (AC) $106 /year 387

Annual Energy Cost Saving (AECS) $106 /year 1,740 

Annual Refrigerant Cost Saving (ARCS) $106 /year N/A 

Net Savings (NS) $106 /year 1350 

Net Savings per Unit of GHG Emissions Reductions 

(NSGR) $/ton CO2 eq. 177.6 

Net Savings per Unit of Energy Use Reduction (NSER) $/106 BTU 14.4 

Net Savings per Unit of Refrigerant Use Reduction 

(NSRR) $/lb N/A 

Simple Payback Period (SPP) years 0.62 a

 These assessments are based on the assumptions that these best practices reach their potential 

maximum market shares in 2025.
150

 iv. Total GHG emissions reductions due to fuel use reduction are 

estimated to be 4.55×106 tons CO2 eq. in 2003. 

( ) 4.55 10 tons CO eq. 10 BTU

0.0808 tons CO eq. 5.63 10 10 BTU 2

6

6

2 7 6 × × = ×

(c) Results: Since total GHG emissions for the truck mode is estimated to grow 

by 67%, which is explained in Section 1.2, the estimated 2025 

annual GHG emissions reductions are 7.60×106

 tons CO2 eq. 

E. Estimate of annual energy use reduction: 

i. Fuel use reduction for this practice in 2003 is estimated to be 56.3×1012 BTU, 

explained in Appendix A.4.D. 

ii. Since total energy use for the truck mode is estimated to grow by 67%,4 the estimated 

annual energy use reduction in 2025 is 93.9×1012 BTU. 

F. Estimate of unit GHG emissions reductions: 

ton mile

0.034 lb CO eq.

ton

2,000 lbs . 453 10 ton miles

7.60 10 tons CO eq 2

9

2

6

− =















× 















× −

×

G. Estimate of unit energy use reduction: 

( )

ton mile

207.3 BTU . 453 10 ton miles

9.39 10 10 BTU

9

7 6

− = 















× −

×

H. Estimate of capital cost 

i. The capital cost of a direct-fired heater is estimated to be $3,200 in 1996,27 but it has 

been re-estimated to be $880 per truck in 2006.136 Total capital cost for all trucks 

with sleeper cab in 2003 is estimated to be $596.3 ×106. 
151

6 677,600 trucks $596.3 10

truck

$880

× = ×

ii. Since total truck number is estimated to grow by 67%, which is explained in Appendix 

A.1.A, total capital cost for all trucks with sleeper cab in 2025 is estimated to be 

$995.8 ×106

. 

I. Estimate of annual O & M cost

i. The annual maintenance cost of a direct-fired heater is estimated to be $110 per 

truck.128 Total O & M cost for all trucks with sleeper cab in 2003 is estimated to be 

$74.5 ×106. 

6 677,600 trucks $74.54 10

truck

$110

× = ×

ii. Since total truck number is estimated to grow by 67%, which is explained in Appendix 

A.1.A, total O & M cost for all trucks with sleeper cab in 2025 is estimated to be 

$124.5 ×106

. 

J. Estimate of annualized cost: 

i. The life-time is estimated to be 5 years.51 

ii. Fixed charge factor is estimated to be 0.264. 

( )

( )

0.264

3.79

1

1 0.1

1

1

arg 5

1

= =

































+

=

∑i=

i

Fixed ch e factor a

iii. ( ) 6 6 6 $995.8×10 ×0.264 + $124.5×10 = $387.4×10

iv. The estimated of annualized cost in 2025 is 387.4×106

. 

K. Estimate of energy cost reduction: 

(a) Assumption: Diesel fuel price in 2025 is the same as the price of the second 

season of 2005, which is $2.56/gallon ( = $18.5/106 BTU).114 

(b) Calculation: ( ) 9

6

7 6 $1.74 10

10 BTU

$18.5 9.39 ×10 10 BTU ×× = ×
152

(c) Results: The estimated energy cost reduction in 2025 is $1.74 × 109. 

L. Estimate of net savings: 

 i. 9 9 6 $1.74×10 − $0.39×10 = $1350×10

 ii. The estimated net savings in 2025 is $1350 × 106

. 

M. Estimate of net savings per unit of GHG emissions reductions: 

ton CO eq.

$177.6

7.6 10 tons CO eq.

$1350 10

2 2

6

6

= ×

×

N. Estimate of net savings per unit of energy use reduction: 

10 BTU

$14.4

93.9 10 BTU

$1350 10

12 6

6

= ×

×

O. Estimate of simple payback period: 

( ) 0.62 years $1.74 10 $0.125 10

$0.996 10

9 9

9

= × − ×

×
153

Appendix A.5 Best Practice 1-5: Direct-fired Heaters with Thermal Storage Units

This best practice is assessed qualitatively. Table A-5 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table A-5. Simplified Summary Table for Best Practice 1-5, Direct-Fired Heaters with Thermal 

Storage Units 

Attribute Description 

Practice Name Direct-Fired Heaters with Thermal Storage Units 

Mode Type Truck 

Subgroup Anti-Idling 

Responsible Parties 1, 2, 5, 16, 18, 19

Target Parties 1, 2, 4, 6

Target GHGs CO2

Strategy Type Technology 

Practice Goals 

Goal is to have all trucks with sleeper cabs participate. The reductions 

in modal GHG emissions and energy use in 2025 would be 2.88% and 

2.97%, respectively. 

Developmental Status P 

Practice Summary The combination of direct-fired heaters and thermal storage units, which 

consists of a phase change material for storing heating or cooling energy, 

supplies heating and cooling, but no electrical power, to the sleeper 

compartment when the base engine is off. 

Potential Reductions in 

Modal GHG Emissions 

2.88% 

Potential Reduction in 

Modal Energy Use 

2.97% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information N/A 

Benefits and Drawbacks This system is probably the most energy-efficient anti-idling practice. 

The disadvantage of this practice is that it supplies no electricity, and 

requires power from the vehicle’s batteries. 
154

Appendix A.6 Best Practice 1-6: Enhanced Air Conditioning System I - for Direct 

Emissions 

This best practice is assessed qualitatively. Table A-6 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table A-6. Simplified Summary Table for Best Practice 1-6, Enhanced Air Conditioning 

System I - for Direct Emissions 

Attribute Description 

Practice Name Enhanced Air Conditioning System I - for Direct Emissions 

Mode Type Truck 

Subgroup Air Conditioning System Improvement 

Responsible Parties 1, 2, 4, 5, 6, 11, 18, 19

Target Parties 1, 2, 4, 6, 7

Target GHGs HFC 

Strategy Type Technology 

Practice Goals Goal is to have all trucks participate. The reductions in modal GHG 

emissions in 2025 would be 0.88%. 

Developmental Status P 

Practice Summary Enhanced air conditioning systems can reduce direct GHG emissions by 

reducing the leakage of HFC-134a. The refrigerant leakage rates can 

be decreased through the use of low permeable hoses, improved hose 

ends and connectors, and improved compressor shaft seals. 

Potential Reductions in 

Modal GHG Emissions 

0.88% 

Potential Reduction in 

Modal Energy Use 

N/A 

Potential Reduction in 

Modal HFC Use 

35.3% 

Cost Information The incremental capital cost of this system is approximately $33 per 

truck. 

Benefits and Drawbacks This system can reduce a lot of refrigerant leakage for the truck mode, 

and save the cost for recharge the refrigerant. Safety characteristics 

of this system have no change because the same refrigerant is used. 

There is not as yet a standard method for testing and certifying the 

leakage rate of an enhanced system is in the developmental stage. 
155

Appendix A.7 Best Practice 1-7: Enhanced Air Conditioning System II - for Indirect 

Emissions 

This best practice is assessed qualitatively. Table A-7 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table A-7. Simplified Summary Table for Best Practice 1-7, Enhanced Air Conditioning 

System II - for Indirect Emissions 

Attribute Description 

Practice Name Enhanced Air Conditioning System II - for Indirect Emissions 

Mode Type Truck 

Subgroup Air Conditioning System Improvement 

Responsible Parties 1, 2, 4, 5, 6, 11, 18, 19

Target Parties 1, 2, 4, 6, 7

Target GHGs CO2

Strategy Type Technology 

Practice Goals 

Goal is to have all trucks participate. The reductions in modal GHG 

emissions and energy use in 2025 would be 0.18% and 0.19%, 

respectively. 

Developmental Status C 

Practice Summary Enhanced air conditioning systems for reducing indirect GHG emissions 

can decrease base engine load requirements from mobile A/C systems. 

This system replaces fixed displacement compressors (FDCs) with 

externally controlled variable displacement compressors (VDC), and 

uses improved control systems, and improved condensers and 

evaporators. 

Potential Reductions in 

Modal GHG Emissions 

0.18% 

Potential Reduction in 

Modal Energy Use 

0.19% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information The incremental capital cost of this system is approximately $7 per 

truck. 

Benefits and Drawbacks This system can reduce energy use for operating A/C, and save energy 

cost. The benefit of reducing engine load is only available in hot 

weather when the A/C system is used. 
156

Appendix A.8 Best Practice 1-8: Alternative Refrigerants - CO2

This best practice is assessed qualitatively. Table A-8 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table A-8. Simplified Summary Table for Best Practice 1-8, Alternative Refrigerants - CO2 

Attribute Description 

Practice Name Alternative Refrigerants - CO2 

Mode Type Truck 

Subgroup Air Conditioning System Improvement 

Responsible Parties 1, 2, 4, 5, 6, 11, 16, 18, 19

Target Parties 1, 2, 4, 6, 7

Target GHGs HFC 

Strategy Type Technology 

Practice Goals Goal is to have all trucks participate. The reductions in modal GHG 

emissions in 2025 would be 2.47%. 

Developmental Status N 

Practice Summary The current widely used refrigerant, HFC-134a, has GWP = 1,300, 

whereas CO2 has GWP = 1. Therefore, CO2 is being investigated as an 

alternative refrigerant. 

Potential Reductions in 

Modal GHG Emissions 

2.47% 

Potential Reduction in 

Modal Energy Use 

N/A 

Potential Reduction in 

Modal HFC Use 

99.9% 

Cost Information The incremental capital cost of CO2 air conditioning system is $42.5 

per truck, including $20 for upgrading system hoses and components 

for higher pressure operating conditions and $22.5 for additional 

safety equipment. Thus, the incremental capital cost of CO2 may be 

increased to $70 per truck, including $20 for upgrading system and 

$50 for secondary loop designs. 

Benefits and Drawbacks This system uses alternative refrigerant with very low GWP. Safety 

assessment and potential risk mitigation may be needed because of 

different safety characteristics of this alternative refrigerant compared 

to HFC-134a. 
157

Appendix A.9 Best Practice 1-9: Alternative Refrigerants - HFC-152a 

This best practice is assessed qualitatively. Table A-9 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table A-9. Simplified Summary Table for Best Practice 1-9, Alternative Refrigerants - 

HFC-152a 

Attribute Description 

Practice Name Alternative Refrigerants - HFC-152a 

Mode Type Truck 

Subgroup Air Conditioning System Improvement 

Responsible Parties 1, 2, 4, 5, 6, 11, 16, 18, 19

Target Parties 1, 2, 4, 6, 7

Target GHGs HFC 

Strategy Type Technology 

Practice Goals Goal is to have all trucks participate. The reductions in modal GHG 

emissions in 2025 would be 2.35%. 

Developmental Status N 

Practice Summary The current widely used refrigerant, HFC-134a, has GWP = 1,300, 

whereas HFC-152a has GWP = 120. Therefore, HFC-152a is being 

investigated as an alternative refrigerant. 

Potential Reductions in 

Modal GHG Emissions 

2.35% 

Potential Reduction in 

Modal Energy Use 

N/A 

Potential Reduction in 

Modal HFC Use 

91% 

Cost Information The incremental capital cost of HFC-152a air conditioning system is 

from $22.5 per truck for additional safety equipment, including 

in-cabin leak sensors and engine compartment evacuation valves, to 

$50 per truck for secondary loop designs. 

Benefits and Drawbacks This system uses alternative refrigerant with low GWP. The 

transition from HFC-134a to HFC-152a would be relatively easy 

(compared to a transition to CO2) since these two refrigerants have 

similar thermodynamic properties and A/C system components need 

less modification. The flammability of this alternative refrigerant, 

although moderate, motivates the need for additional safety 

assessment and potential risk mitigation 
158

Appendix A.10 Best Practice 1-10: Alternative Refrigerants - HC 

This best practice is assessed qualitatively. Table A-10 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table A-10. Simplified Summary Table for Best Practice 1-10, Alternative Refrigerants - HC 

Attribute Description 

Practice Name Alternative Refrigerants - HC 

Mode Type Truck 

Subgroup Air Conditioning System Improvement 

Responsible Parties 1, 2, 4, 5, 6, 11, 16, 18, 19

Target Parties 1, 2, 4, 6, 7

Target GHGs HFC 

Strategy Type Technology 

Practice Goals Goal is to have all trucks participate. The reductions in modal GHG 

emissions in 2025 would be 2.46%. 

Developmental Status N 

Practice Summary The current widely used refrigerant, HFC-134a, has GWP = 1,300, 

whereas propane has GWP = 20. Therefore, propane is being 

investigated as an alternative refrigerant. 

Potential Reductions in 

Modal GHG Emissions 

2.46% 

Potential Reduction in 

Modal Energy Use 

N/A 

Potential Reduction in 

Modal HFC Use 

98.5% 

Cost Information The incremental capital cost of HC air conditioning system is from 

$22.5 per truck for additional safety equipment, including in-cabin 

leak sensors and engine compartment evacuation valves, to $50 per 

truck for secondary loop designs. 

Benefits and Drawbacks This system uses alternative refrigerant with low GWP. However, 

this system may use 10% more energy for the operation of vehicle air 

conditioners and increases indirect GHG emissions. The 

flammability of this alternative refrigerant, although moderate, 

motivates the need for additional safety assessment and potential risk 

mitigation. Release of propane to the atmosphere may also increase 

tropospheric ozone formation. 
159

Appendix A.11 Best Practice 1-11: Vehicle Profile Improvement I - Cab Top Deflector, 

Sloping Hood and Cab Side Flares 

This best practice is assessed qualitatively. Table A-11 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table A-11. Simplified Summary Table for Best Practice 1-11, Vehicle Profile Improvement I - 

Cab Top Deflector, Sloping Hood and Cab Side Flares 

Attribute Description 

Practice Name Vehicle Profile Improvement I - Cab Top Deflector, Sloping Hood and 

Cab Side Flares 

Mode Type Truck 

Subgroup Aerodynamic Drag Improvement 

Responsible Parties 1, 2, 5, 6

Target Parties 1, 2, 6

Target GHGs CO2

Strategy Type Technology 

Practice Goals 

Goal is to have all trucks participate. The reductions in modal GHG 

emissions and energy use in 2025 would be 1.43% and 1.47%, 

respectively. 

Developmental Status C 

Practice Summary These add-on devices can reduce truck tractor aerodynamic drag, 

increase their fuel efficiency and reduce GHG emissions. 

Potential Reductions in 

Modal GHG Emissions 

1.43% 

Potential Reduction in 

Modal Energy Use 

1.47% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information The incremental capital cost of this system is approximately $750 per 

truck. 

Benefits and Drawbacks These add-on devices that reduce aerodynamic drag can reduce 

energy use and GHG emissions. Although this best practice 

increases truck weight slightly, the estimated reduction in fuel use and 

GHG emissions takes this into account. 
160

Appendix A.12 Best Practice 1-12: Vehicle Profile Improvement II - Closing and 

Covering of Gap between Tractor and Trailer, Aerodynamic Bumper, 

Underside Air Baffles, and Wheel Well Covers 

This best practice is assessed qualitatively. Table A-12 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table A-12. Simplified Summary Table for Best Practice 1-12, Vehicle Profile Improvement 

II - Closing and Covering of Gap Between Tractor and Trailer, Aerodynamic 

Bumper, Underside Air Baffles, and Wheel Well Covers 

Attribute Description 

Practice Name 

Vehicle Profile Improvement II - Closing and Covering of Gap Between 

Tractor and Trailer, Aerodynamic Bumper, Underside Air Baffles, and 

Wheel Well Covers 

Mode Type Truck 

Subgroup Aerodynamic Drag Improvement 

Responsible Parties 1, 2, 5, 6

Target Parties 1, 2, 6

Target GHGs CO2

Strategy Type Technology 

Practice Goals 

Goal is to have all trucks participate. The reductions in modal GHG 

emissions and energy use in 2025 would be 2.37% and 2.44%, 

respectively. 

Developmental Status C 

Practice Summary These add-on devices can reduce truck side and underside aerodynamic 

drag, increase their fuel efficiency and reduce GHG emissions. 

Potential Reductions in 

Modal GHG Emissions 

2.37% 

Potential Reduction in 

Modal Energy Use 

2.44% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information The incremental capital cost of this system is approximately $1,500 

per truck. 

Benefits and Drawbacks These add-on devices that reduce aerodynamic drag can reduce 

energy use and GHG emissions. Although this best practice 

increases truck weight slightly, the estimated reduction in fuel use and 

GHG emissions takes this into account. 
161

Appendix A.13 Best Practice 1-13: Vehicle Profile Improvement III - Trailer or Van 

Leading and Trailing Edge Curvatures 

This best practice is assessed qualitatively. Table A-13 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table A-13. Simplified Summary Table for Best Practice 1-13, Vehicle Profile Improvement III 

- Trailer or Van Leading and Trailing Edge Curvatures 

Attribute Description 

Practice Name Vehicle Profile Improvement III - Trailer or Van Leading and Trailing 

Edge Curvatures 

Mode Type Truck 

Subgroup Aerodynamic Drag Improvement 

Responsible Parties 1, 2, 5, 6

Target Parties 1, 2, 6

Target GHGs CO2

Strategy Type Technology 

Practice Goals 

Goal is to have all trucks participate. The reductions in modal GHG 

emissions and energy use in 2025 would be 1.24% and 1.28%, 

respectively. 

Developmental Status C 

Practice Summary These add-on devices can reduce truck trailer (or van) aerodynamic 

drag, increase their fuel efficiency and reduce GHG emissions. 

Potential Reductions in 

Modal GHG Emissions 

1.24% 

Potential Reduction in 

Modal Energy Use 

1.28% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information The incremental capital cost of this system is approximately $500 per 

truck. 

Benefits and Drawbacks These add-on devices that reduce aerodynamic drag can reduce 

energy use and GHG emissions. 
162

Appendix A.14 Best Practice 1-14: Pneumatic Aerodynamic Drag Reduction 

This best practice is assessed qualitatively. Table A-14 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table A-14. Simplified Summary Table for Best Practice 1-14, Pneumatic Aerodynamic Drag 

Reduction 

Attribute Description 

Practice Name Pneumatic Aerodynamic Drag Reduction 

Mode Type Truck 

Subgroup Aerodynamic Drag Improvement 

Responsible Parties 1, 2, 4, 5, 6, 7, 16, 18, 19

Target Parties 1, 2, 4, 6, 7

Target GHGs CO2

Strategy Type Technology 

Practice Goals 

Goal is to have all combination trucks participate. The reductions in 

modal GHG emissions and energy use in 2025 would be 2.17% and 

2.24%, respectively. 

Developmental Status N 

Practice Summary This system blows air from slots at the rear of the trailers of heavy-duty 

vehicles to reduce aft-end aerodynamic drag and reduce energy use and 

GHG emissions. 

Potential Reductions in 

Modal GHG Emissions 

2.17% 

Potential Reduction in 

Modal Energy Use 

2.24% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information The estimated incremental capital cost is $2,500, but could be as high 

as $5,250. 

Benefits and Drawbacks This system that reduces aerodynamic drag can reduce energy use and 

GHG emissions. If used in combination with another best practice, 

such as Best Practice 1-12, there may be a negative synergistic effect 

in that the total improvement in aerodynamics is less than the linear 

sum of improvements from individual practices. 
163

Appendix A.15 Best Practice 1-15: Planar Boat Tail Plates on a Tractor-Trailer 

This best practice is assessed qualitatively. Table A-15 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table A-15. Simplified Summary Table for Best Practice 1-15, Planar Boat Tail Plates on a 

Tractor-Trailer 

Attribute Description 

Practice Name Planar Boat Tail Plates on a Tractor-Tailer 

Mode Type Truck 

Subgroup Aerodynamic Drag Improvement 

Responsible Parties 1, 2, 3, 4, 5, 6, 7, 12, 16, 18, 19

Target Parties 1, 2, 3, 4, 5, 6, 7

Target GHGs CO2

Strategy Type Technology 

Practice Goals 

Goal is to have all combination trucks participate. The reductions in 

modal GHG emissions and energy use in 2025 would be 3.76% and 

3.88%, respectively. 

Developmental Status N 

Practice Summary Planar boat tail plates are testing add-on devices that reduce aft-end 

aerodynamic drag. These devices are rectangular plates mounted to the 

after-end of a trailer that reduce the wake of trucks. 

Potential Reductions in 

Modal GHG Emissions 

3.76% 

Potential Reduction in 

Modal Energy Use 

3.55% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information N/A 

Benefits and Drawbacks These add-on devices that reduce aerodynamic drag can reduce 

energy use and GHG emissions. The drawback of this practice is 

that it may interfere with loading and unloading operations, 

depending on the design. 
164

Appendix A.16 Best Practice 1-16: Vehicle Load Profile Improvement 

This best practice is assessed qualitatively. Table A-16 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table A-16. Simplified Summary Table for Best Practice 1-16, Vehicle Load Profile 

Improvement 

Attribute Description 

Practice Name Vehicle Load Profile Improvement 

Mode Type Truck 

Subgroup Aerodynamic Drag Improvement 

Responsible Parties 1, 2, 3, 5

Target Parties 1, 2, 3, 5, 6

Target GHGs CO2

Strategy Type Technology 

Practice Goals 

Goal is to have all non-van trailers within combination trucks 

participate. The reductions in modal GHG emissions and energy use in 

2025 would be 0.43% and 0.44%, respectively. 

Developmental Status C 

Practice Summary Aerodynamic drag can be reduced by the use of a streamlined load 

profile for a trailer. This practice keeps the load profile of a trailer as 

low as possible and secures tarpaulins to smooth air flow to reduce 

energy use and GHG emissions. 

Potential Reductions in 

Modal GHG Emissions 

0.43% 

Potential Reduction in 

Modal Energy Use 

0.44% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information N/A 

Benefits and Drawbacks This low-tech option that reduces aerodynamic drag can reduce 

energy use and GHG emissions. The drawback of this practice is 

that extra work for loading and unloading operations may be required. 
165

Appendix A.17 Best Practice 1-17: Automatic Tire Inflation Systems 

This best practice is assessed qualitatively. Table A-17 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table A-17. Simplified Summary Table for Best Practice 1-17, Automatic Tire Inflation 

Systems 

Attribute Description 

Practice Name Automatic Tire Inflation Systems 

Mode Type Truck 

Subgroup Tire Rolling Resistance Improvement 

Responsible Parties 1, 2, 4, 5, 6, 7, 8, 12

Target Parties 1, 2, 4, 6, 7

Target GHGs CO2

Strategy Type Technology 

Practice Goals 

Goal is to have all combination trucks participate. The reductions in 

modal GHG emissions and energy use in 2025 would be 0.56% and 

0.58%, respectively. 

Developmental Status C 

Practice Summary These systems can keep tires to the right pressure by monitoring and 

continually adjusting the level of pressurized air in tires. With properly 

vehicle tire inflation, tire rolling resistance is decreased and fuel use is 

reduced. 

Potential Reductions in 

Modal GHG Emissions 

0.56% 

Potential Reduction in 

Modal Energy Use 

0.58% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information The estimated incremental capital cost is $900. The tire 

maintenance cost saving is about $200 annually. 

Benefits and Drawbacks While these systems are installed, drivers do not need to check tire 

pressure manually and can pay less attention to their truck tires. 
166

Appendix A.18 Best Practice 1-18: Wide-Base Tires 

This best practice is assessed qualitatively. Table A-18 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table A-18. Simplified Summary Table for Best Practice 1-18, Wide-Base Tires 

Attribute Description 

Practice Name Wide-Base Tires 

Mode Type Truck 

Subgroup Tire Rolling Resistance Improvement 

Responsible Parties 1, 2, 5, 6, 7

Target Parties 1, 2, 6

Target GHGs CO2

Strategy Type Technology 

Practice Goals 

Goal is to have all combination trucks participate. The reductions in 

modal GHG emissions and energy use in 2025 would be 2.03% and 

2.10%, respectively. 

Developmental Status C 

Practice Summary Dual tires that combination trucks usually have are heavy and also 

produce high rolling resistance. Single wide-base tires can replace 

these dual tires on combination trucks. Wide-base tires that have lower 

weight and produce lower rolling resistance reduce energy use. 

Potential Reductions in 

Modal GHG Emissions 

2.03% 

Potential Reduction in 

Modal Energy Use 

2.10% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information The estimated incremental capital cost is $700 in average. New 

trucks with wide-base tires are possibly cheaper than with dual tires, 

but retrofitting existing trucks have higher cost. 

Benefits and Drawbacks This practice has lower weight and produces lower rolling resistance. 

Aerodynamic drag and pass-by noise may also be decreased slightly. 

By using single instead of dual tires, there is a need for increased 

attention to tire inflation pressure for safety reasons 
167

Appendix A.19 Best Practice 1-19: Low-Rolling-Resistance Tires 

This best practice is assessed qualitatively. Table A-19 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table A-19. Simplified Summary Table for Best Practice 1-19, Low-Rolling-Resistance Tires 

Attribute Description 

Practice Name Low-Rolling-Resistance Tires 

Mode Type Truck 

Subgroup Tire Rolling Resistance Improvement 

Responsible Parties 1, 2, 5, 6, 7

Target Parties 1, 2, 6

Target GHGs CO2

Strategy Type Technology 

Practice Goals 

Goal is to have all trucks participate. The reductions in modal GHG 

emissions and energy use in 2025 would be 2.83% and 2.91%, 

respectively. 

Developmental Status P 

Practice Summary Trucks with low-rolling resistance tires are fuel-efficient because of the 

reduction of tire rolling resistance. 

Potential Reductions in 

Modal GHG Emissions 

2.83% 

Potential Reduction in 

Modal Energy Use 

2.91% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information The estimated incremental capital cost is $550. 

Benefits and Drawbacks This practice produces lower rolling resistance. However, the 

requirements for higher inflation pressure and high monitoring 

frequency may limit the extent of their market penetration. The fuel 

saving advantage tends to be reduced when these low-resistance tires 

wear down. 
168

Appendix A.20 Best Practice 1-20: Pneumatic Blowing to Reducing Rolling Resistance 

This best practice is assessed qualitatively. Table A-20 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table A-20. Simplified Summary Table for Best Practice 1-20, Pneumatic Blowing to 

Reducing Rolling Resistance 

Attribute Description 

Practice Name Pneumatic Blowing to Reducing Rolling Resistance 

Mode Type Truck 

Subgroup Tire Rolling Resistance Improvement 

Responsible Parties 1, 2, 4, 5, 6, 7, 8, 12, 16, 18, 19

Target Parties 1, 2, 4, 6, 7

Target GHGs CO2

Strategy Type Technology 

Practice Goals 

Goal is to have all combination trucks participate. The reductions in 

modal GHG emissions and energy use in 2025 would be 0.54% and 

0.56%, respectively. 

Developmental Status N 

Practice Summary This system for reducing aft-end aerodynamic drag blows air from slots 

at the rear of the trailers of heavy-duty vehicles. The installation of 

additional pipes, jets, valves, selective blowing, and control system can 

blow air under trucks. These air streams provide a slight lift that 

reduces tire rolling resistance. 

Potential Reductions in 

Modal GHG Emissions 

0.54% 

Potential Reduction in 

Modal Energy Use 

0.56% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information If the pneumatic blowing system for reducing aerodynamic drag has 

been installed on a combination truck, additional $500 capital cost for 

extra components would be needed. 

Benefits and Drawbacks This practice can utilize the air-blowing system to reduce rolling 

resistance and reduce tire wear. This practice may also assist 

conventional truck control and improve safety. However, this 

system may slightly increase dust pollution by dislodging particles on 

the road surface. 

 
169

Appendix A.21 Best Practice 1-21: Hybrid Trucks 

This best practice is assessed quantitatively. Table A-21 summarizes the assessment 

results. This table is in the format of the standardized reporting table for quantitative results. 

The basis of the quantitative estimates is explained.

A. Estimate of total number of vehicles or devices: 

(a) Assumption: The growth rate of medium-duty trucks is the same as the growth 

rate of total trucks for the truck mode from 2003 to 2025. 

(a) 2003 Results: It is estimated that there were 2,824,000 trucks as medium-duty 

trucks in 2003.18 

(b) 2025 Results: Since the growth rates of medium-duty trucks and total trucks are 

the same and the number of total trucks is estimated to grow by 

67% from 2003 to 2025, which is explained in Appendix A.1.A, 

there will be 4,716,000 trucks as medium-duty trucks in 2025. 

B. Estimate of annual transport activity for the mode: 

Annual transport activity for the mode is explained in Appendix A.1. 

C. Estimate of annual transport activity to which a practice is applicable: 

 (a) Assumption: The ratio of annual transport activity of medium-duty trucks to 

annual transport activity of all trucks is proportional to the ratio of 

energy use for medium-duty trucks to energy sue for all trucks. 

(b) Calculation: The ratio of energy use for medium-duty trucks to energy use for 

all trucks is estimated to be 17.8%.20 

(c) Results: Since the ratio is 17.8%, the estimated total ton-miles for 

medium-duty trucks in the U.S. in 2025 will be 373 ×109

ton-miles. 
170

Table A-21. Standardized Reporting Table for Best Practice 1-21, Hybrid Trucksa

Characteristics of the Practice Description 

Practice Name Hybrid Trucks 

Mode Type Truck 

Subgroup Hybrid Propulsion 

Responsible Parties 1, 2, 4, 5, 6, 8, 9, 12, 16, 18, 19, 20, 21, 22

Target Parties 1, 2, 4, 6, 7

Target GHGs CO2

Strategy Type Technology 

Practice Goals 

Goal is to have all local traveled 

medium-duty trucks participate. The 

reductions in modal GHG emissions and 

energy use in 2025 would be 3.4% (24.5 

×106

 tons of CO2 eq.) and 3.5% (300 

×1012 Btu), respectively. 

Developmental Status N 

Practice Summary Hybrid propulsion systems recover or 

recycle energy for braking or deceleration 

to reduce truck fuel use. They help to 

shut off the engine under idling conditions 

within stop-and-go driving. 

Emissions, Energy Use, and Refrigerant Use Unit Value 

Annual Transport Activity for the Mode (ATAM) 109 ton-miles/year 2,098 

Annual Transport Activity to Which a Practice Is 

Applicable (ATAP) 109

 ton-miles/year 373 

Annual GHG Emissions Reductions(AGR) 106 ton CO2 eq./year 24.5 

Annual Energy Use Reduction (AER) 1012 BTU /year 300 

Annual Refrigerant Use Reduction (ARR) lbs/year N/A 

Unit GHG Emissions Reductions (UGER) 10-3 lb CO2 eq./ton-mile 130 

Unit Energy Use Reduction (UER) BTU /ton-mile 804 

Unit Refrigerant Use Reduction (URR) lbs/ton-mile N/A 

Practice Costs 

Capital Cost I 106 USD ($) 9,210 

Discount Rate I % 10% 

Technical Lifetime of Technology (L) years 15 

Fixed Charge Factor (a) year-1 0.131 

Annual O & M Cost (AOM) $106 /year 1,220 

Annualized Cost (AC) $106 /year 2,430

Annual Energy Cost Saving (AECS) $106 /year 5,620 

Annual Refrigerant Cost Saving (ARCS) $106 /year N/A 

Net Savings (NS) $106 /year 3,190 

Net Savings per Unit of GHG Emissions Reductions 

(NSGR) $/ton CO2 eq. 130 

Net Savings per Unit of Energy Use Reduction (NSER) $/106 BTU 10.6 

Net Savings per Unit of Refrigerant Use Reduction 

(NSRR) $/lb N/A 

Simple Payback Period (SPP) years 2.1 a

 These assessments are based on the assumptions that these best practices reach their potential 

maximum market shares in 2025. 
171

 

D. Estimate of annual GHG emissions reductions: 

(a) Assumption: i. Total GHG emissions reductions are due to energy use. 

ii. Approximately 47% of total travel distance for medium-duty 

trucks is within local area.49 

iii. Hybrid medium-duty trucks traveled locally are estimated to 

increase fuel economy by 71%,49 which is equal to reduce 

energy use by 41.5%. 

(b) Calculation: i. Adopting hybrid medium-duty trucks for local area purpose is 

estimated to reduce energy use for medium-duty trucks by 

19.5%. 

 ( ) 41.5%× 47% = 19.5%

ii. Since the ratio of energy use for medium-duty trucks to energy 

use for all trucks is 17.8%, adopting hybrid medium-duty trucks 

for local area use is estimated to reduce energy use for the whole 

truck mode by 3.49%. 

 ( ) 19.5%×17.8% = 3.49%.

iii. Total energy use reduction in 2003 is estimated to be 1.82×108

(106 BTU) per year. 

 (3.49% 5.21 10 BTU) 1.82 10 BTU. 15 14 × × = ×

iv. Since the truck mode is estimated to grow by 67% from 2003 to 

2025,4

 the estimated annual energy use reduction in 2025 is 

3.0×108 (106 BTU). 

v. Total GHG emissions reductions due to fuel use reduction are 

estimated to be 24.5×106 tons CO2 eq. in 2025. 

 

24.5 10 tons CO eq. 10 BTU

0.0808 tons CO eq. 3.0 10 BTU 2

6

6

14 2 = × 















× ×
172

(c) Results: The annual GHG emissions reductions are estimated to be 

24.5×106 tons CO2 eq. in 2025. 

E. Estimate of annual energy use reduction: 

The estimated annual energy use reduction in 2025 is 300×1012 BTU, estimated in 

Appendix A.21.D. 

F. Estimate of unit GHG emissions reductions: 

ton mile

0.13 lb CO eq.

ton

2,000 lbs . 373 10 ton miles

24.5 10 tons CO eq 2

9

2

6

− =















× 















× −

×

G. Estimate of unit energy use reduction: 

( )

ton mile

803.6 BTU . 373 10 ton miles

3.0 10 10 BTU

9

8 6

− = 















× −

×

H. Estimate of capital cost 

i. The estimated incremental capital cost for a hybrid truck is $3,100 in 2025.49 

 ii. Approximately 63% of medium-duty trucks are used locally.49 

iii. Total incremental capital costs of medium-duty hybrid trucks in 2025 are estimated to 

be $9.21×109

. 

6 9 4.72 10 trucks 63% $9.21 10

truck

$3,100

× × × = ×

I. Estimate of annual O & M cost

(a) Assumption: i. Battery cost is estimated to be 50% of incremental capital cost of 

a hybrid truck.49

ii. Lifetime of battery is estimated to be 5 years. 
173

iii. Discount rate is 10%. 

(b) Calculation: i. Based on the estimated lifetime and discount rate, fixed charged 

factor is estimated to be 0.264. 

ii. Total annual cost for battery is estimated to be $1.22 ×109. 

6 9 50% 0.264 4.72 10 trucks 63% $1.22 10

truck

$3,100

× × × × × = ×

(c) Results: The estimated annual O & M cost is estimated to be $1.22 ×109

. 

J. Estimate of annualized cost: 

(a) Assumption: i. The life-time of hybrid trucks is estimated to be 15 years. 

ii. Discount rate is 10%. 

(b) Calculation: i. Based on the estimated lifetime and discount rate, fixed charged 

factor is estimated to be 0.131. 

ii. ( ) ( ) 9 9 9 $9.21×10 × 0.131 + $1.22×10 = $2.43×10

(c) Results: The estimated annualized cost is estimated to be $2.43 ×109. 

K. Estimate of energy cost reduction: 

(a) Assumption: Diesel fuel price in 2025 is the same as the price of the second 

season of 2005, which is $2.56/gallon ( = $18.5/106 BTU).114 

(b) Calculation: The estimated energy cost reduction in 2003 is $3.37 ×109

. 

( ) 9

6

8 6 $3.37 10

10 BTU

$18.5 1.82 ×10 10 BTU × = ×

(c) Results: Since total energy use for the truck mode is estimated to grow by 

67% from 2003 to 2025,4 the estimated energy cost reduction in 

2025 is $5.62 ×109. 

L. Estimate of net savings: 

9 9 9 $5.62×10 − $2.43×10 = $3.19×10
174

M. Estimate of net savings per unit of GHG emissions reductions: 

ton CO eq.

$130.2

24.5 10 tons CO eq.

$3.19 10

2 2

6

9

= ×

×

N. Estimate of net savings per unit of energy use reduction: 

10 BTU

$10.6

300 10 BTU

$3.19 10

12 6

9

= ×

×

O. Estimate of simple payback period: 

( ) 2.1 years $5.62 10 $1.22 10

$9.21 10

9 9

9

= × − ×

×
175

Appendix A.22 Best Practice 1-22: Lightweight Materials

This best practice is assessed qualitatively. Table A-22 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table A-22. Simplified Summary Table for Best Practice 1-22, Lightweight Materials 

Attribute Description 

Practice Name Lightweight Materials 

Mode Type Truck 

Subgroup Weight Reduction 

Responsible Parties 1, 2, 5, 6, 7, 10, 16, 18, 19

Target Parties 1, 2, 6

Target GHGs CO2

Strategy Type Technology 

Practice Goals 

Goal is to have all trucks participate. The reductions in modal GHG 

emissions and energy use in 2025 would be 4.62% and 4.76%, 

respectively. 

Developmental Status P 

Practice Summary Using high-strength, light-weight components, including aluminum, 

plastics, and others, reduces the weight of trucks that can significantly 

reduce fuel use and reduce GHG emissions. 

Potential Reductions in 

Modal GHG Emissions 

4.62% 

Potential Reduction in 

Modal Energy Use 

4.76% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information The estimated incremental capital cost is $2,000. 

Benefits and Drawbacks Lightweight components can reduce truck fuel use, allow more cargo 

and increase productivity. However, current light-weight materials 

are costly and with no satisfied material characteristics. However, 

current light-weight materials are costly and with no satisfied material 

characteristics. Further research and development for advanced 

materials are needed. 
176

Appendix A.23 Best Practice 1-23: Advanced Transmission 

This best practice is assessed qualitatively. Table A-23 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table A-23. Simplified Summary Table for Best Practice 1-23, Advanced Transmission 

Attribute Description 

Practice Name Advanced Transmission 

Mode Type Truck 

Subgroup Transmission Improvement 

Responsible Parties 1, 2, 4, 5, 6, 9, 16, 18, 19

Target Parties 1, 2, 4, 6, 7

Target GHGs CO2

Strategy Type Technology 

Practice Goals 

Goal is to have all trucks participate. The reductions in modal GHG 

emissions and energy use in 2025 would be 0.97% and 1.00%, 

respectively. 

Developmental Status P 

Practice Summary A continuously variable transmission (CVT) has belt-connected pulleys 

that can optimize speed-load conditions and reduce fuel use. 

Mechanical losses in a transmission can be reduced by the reduction of 

gear surface roughness, the use of low-friction coatings, the use of new 

gear materials, and the use of the lock-up torque converter. 

Potential Reductions in 

Modal GHG Emissions 

0.97% 

Potential Reduction in 

Modal Energy Use 

1.00% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information The estimated incremental capital cost is $1,000. 

Benefits and Drawbacks CVTs have smoother operation and allow the engine speed to remain 

at the level of peak efficiency to reduce energy use and emissions. 

Driver training may be needed to avoid the confusion because the 

sound of the engine with traditional transmissions changes for 

acceleration operations but the sound of the engine with improved 

transmission does not change in the condition of acceleration. 
177

Appendix A.24 Best Practice 1-24: Transmission Friction Reduction through 

Low-Viscosity Transmission Lubricants 

This best practice is assessed qualitatively. Table A-24 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table A-24. Simplified Summary Table for Best Practice 1-24, Transmission Friction 

Reduction through Low-Viscosity Transmission Lubricants 

Attribute Description 

Practice Name Transmission Friction Reduction through Low-Viscosity Transmission 

Lubricants 

Mode Type Truck 

Subgroup Transmission Improvement 

Responsible Parties 1, 2, 4, 5, 9, 15

Target Parties 1, 2, 4, 6, 7

Target GHGs CO2

Strategy Type Technology 

Practice Goals 

Goal is to have all trucks participate. The reductions in modal GHG 

emissions and energy use in 2025 would be 0.92% and 0.95%, 

respectively. 

Developmental Status C 

Practice Summary Low-viscosity transmission fluids can be adopted to decrease 

transmission friction and also reduce fuel consumption. 

Potential Reductions in 

Modal GHG Emissions 

0.92% 

Potential Reduction in 

Modal Energy Use 

0.95% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information The estimated incremental capital cost is $500. 

Benefits and Drawbacks Low-viscosity lubricants can reduce energy use, but it typically costs 

more than conventional lubricants. 
178

Appendix A.25 Best Practice 1-25: Engine Friction Reduction through Low-Viscosity 

Engine Lubricants 

This best practice is assessed qualitatively. Table A-25 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table A-25. Simplified Summary Table for Best Practice 1-25, Engine Friction Reduction 

through Low-Viscosity Engine Lubricants 

Attribute Description 

Practice Name Engine Friction Reduction through Low-Viscosity Engine Lubricants 

Mode Type Truck 

Subgroup Diesel Engine Improvement 

Responsible Parties 1, 2, 4, 5, 9, 15

Target Parties 1, 2, 4, 6, 7

Target GHGs CO2

Strategy Type Technology 

Practice Goals 

Goal is to have all trucks participate. The reductions in modal GHG 

emissions and energy use in 2025 would be 1.81% and 1.86%, 

respectively. 

Developmental Status C 

Practice Summary Low-viscosity engine lubricants are made from synthetic or mineral oil 

blends for the purpose of reducing internal engine friction. 

Potential Reductions in 

Modal GHG Emissions 

1.81% 

Potential Reduction in 

Modal Energy Use 

1.86% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information The estimated incremental capital cost is $500. 

Benefits and Drawbacks Low-viscosity lubricants can reduce energy use, but it typically costs 

more than conventional lubricants. 
179

Appendix A.26 Best Practice 1-26: Increased Peak Cylinder Pressures 

This best practice is assessed qualitatively. Table A-26 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table A-26. Simplified Summary Table for Best Practice 1-26, Increased Peak Cylinder 

Pressures 

Attribute Description 

Practice Name Increased Peak Cylinder Pressures 

Mode Type Truck 

Subgroup Diesel Engine Improvement 

Responsible Parties 1, 2, 4, 5, 6, 9

Target Parties 1, 2, 4, 6, 7

Target GHGs CO2

Strategy Type Technology 

Practice Goals 

Goal is to have all heavy-duty trucks participate. The reductions in 

modal GHG emissions and energy use in 2025 would be 3.07% and 

3.16%, respectively. 

Developmental Status C 

Practice Summary Diesel engine thermal efficiency is proportion to the peak pressures that 

can be achieved in the engine cylinders. However, the peak cylinder 

pressures are constrained by the strength and durability of the engine 

materials over the design service life of the engine. Measures that 

result in better materials that enable higher peak pressures can lead to 

higher engine efficiency. 

Potential Reductions in 

Modal GHG Emissions 

3.07% 

Potential Reduction in 

Modal Energy Use 

3.16% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information The estimated incremental capital cost is $1,000. 

Benefits and Drawbacks They can withstand higher peak cylinder pressures and increase 

thermal efficiency. 
180

Appendix A.27 Best Practice 1-27: Improved Fuel Injectors 

This best practice is assessed qualitatively. Table A-27 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table A-27. Simplified Summary Table for Best Practice 1-27, Improved Fuel Injectors 

Attribute Description 

Practice Name Improved Fuel Injectors 

Mode Type Truck 

Subgroup Diesel Engine Improvement 

Responsible Parties 1, 2, 4, 5, 6, 9

Target Parties 1, 2, 4, 6, 7

Target GHGs CO2

Strategy Type Technology 

Practice Goals 

Goal is to have all trucks participate. The reductions in modal GHG 

emissions and energy use in 2025 would be 5.49% and 5.66%, 

respectively. 

Developmental Status P 

Practice Summary Incorrect fuel injection causes a reduction of combustion efficiency and 

an increase of emissions. The improvement of fuel injection via better 

control is expected to reduce truck fuel use. For example, advanced 

fuel injection systems, such as electronic unit injectors or common rail 

injectors with increased fuel injection pressure, are estimate to result in 

better control of the fuel injection rate and injection timing, and to 

produce finer vaporization of the fuel spray. 

Potential Reductions in 

Modal GHG Emissions 

5.49% 

Potential Reduction in 

Modal Energy Use 

5.66% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information The estimated incremental capital cost is $1,500. 

Benefits and Drawbacks These systems have better control of the fuel injection rate, injection 

timing, and finer fuel spray. However, a drawback of higher 

injection pressures is the need to have stronger fuel-injection system 

and other engine components that withstand the higher pressures. 

The improved high pressure injectors may have leakage problem after 

a period of operation time. Regular diagnosis is needed to identify 

and address this problem. 
181

Appendix A.28 Best Practice 1-28: Turbocharged, Direct Injection to Improved 

Thermal Management 

This best practice is assessed qualitatively. Table A-28 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table A-28. Simplified Summary Table for Best Practice 1-28, Turbocharged, Direct Injection 

to Improved Thermal Management 

Attribute Description 

Practice Name Turbocharged, Direct Injection to Improved Thermal Management 

Mode Type Truck 

Subgroup Diesel Engine Improvement 

Responsible Parties 1, 2, 4, 5, 6, 9

Target Parties 1, 2, 4, 6, 7

Target GHGs CO2

Strategy Type Technology 

Practice Goals 

Goal is to have all medium-duty trucks participate. The reductions in 

modal GHG emissions and energy use in 2025 would be 0.82% and 

0.85%, respectively. 

Developmental Status C 

Practice Summary Turbocharger is a turbine that is driven by the exhaust air flow form the 

engine and increase air intake. Advanced turbochargers that drive more 

air into the cylinder increase combustion efficiency and allow direct 

injectors to inject more fuel into cylinders. 

Potential Reductions in 

Modal GHG Emissions 

0.82% 

Potential Reduction in 

Modal Energy Use 

0.85% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information The estimated incremental capital cost is $700-1,000. 

Benefits and Drawbacks The combination of turbocharger and direct injector allow for precise 

control of the fuel/air mixture which produce more power and higher 

fuel efficiency. 
182

Appendix A.29 Best Practice 1-29: Thermoelectric Technology to Recovery Waste 

Heat 

This best practice is assessed qualitatively. Table A-29 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table A-29. Simplified Summary Table for Best Practice 1-29, Thermoelectric Technology to 

Recovery Waste Heat 

Attribute Description 

Practice Name Thermoelectric Technology to Recovery Waste Heat 

Mode Type Truck 

Subgroup Diesel Engine Improvement 

Responsible Parties 1, 2, 4, 5, 6, 9

Target Parties 1, 2, 4, 6, 7

Target GHGs CO2

Strategy Type Technology 

Practice Goals 

Goal is to have all heavy-duty trucks participate. The reductions in 

modal GHG emissions and energy use in 2025 would be 5.22% and 

5.38%, respectively. 

Developmental Status N 

Practice Summary Overall engine thermal efficiency can be increased if new materials and 

technologies can be developed and implement for improved thermal 

management. An example is the conversion of engine waste heat to 

electrical energy. Such systems are not commercially available and are 

undergoing development. Combining thermoelectric materials and 

advanced heat exchangers may recover waste heat in order to produce 

electricity. 

Potential Reductions in 

Modal GHG Emissions 

5.22% 

Potential Reduction in 

Modal Energy Use 

5.38% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information The estimated incremental capital cost is $2,000. 

Benefits and Drawbacks Thermoelectric converter technology needs further research and 

development (R & D) to increase its currently low conversion 

efficiency. The estimates reported here presume that such R & D 

will be successful. 
183

Appendix A.30 Best Practice 1-30: Electric Auxiliaries 

This best practice is assessed qualitatively. Table A-30 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table A-30. Simplified Summary Table for Best Practice 1-30, Electric Auxiliaries 

Attribute Description 

Practice Name Electric Auxiliaries 

Mode Type Truck 

Subgroup Accessory Load Reduction 

Responsible Parties 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 12

Target Parties 1, 2, 3, 4, 6, 7

Target GHGs CO2

Strategy Type Technology 

Practice Goals 

Goal is to have all trucks participate. The reductions in modal GHG 

emissions and energy use in 2025 would be 1.43% and 1.48%, 

respectively. 

Developmental Status C 

Practice Summary Most mechanical auxiliaries operate whenever truck base engines are 

running, which waste energy when the auxiliaries are not needed. The 

replacement of gear- or belt-driven auxiliaries by electrically driven 

systems can decouple mechanical loads from the base engine and reduce 

energy use. An electric truck can use a generator to produce electricity 

as power source for electric auxiliaries. 

Potential Reductions in 

Modal GHG Emissions 

1.43% 

Potential Reduction in 

Modal Energy Use 

1.48% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information The estimated incremental capital cost is $500. 

Benefits and Drawbacks More electric trucks can reduce fuel use rate and reduce GHG 

emissions. The smaller generator for this practice may need 

pollution control devices in order to comply with future emissions 

standards. 
184

Appendix A.31 Best Practice 1-31: Fuel-Cell-Operated Auxiliaries 

This best practice is assessed qualitatively. Table A-31 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table A-31. Simplified Summary Table for Best Practice 1-31, Fuel-Cell-Operated Auxiliaries 

Attribute Description 

Practice Name Fuel-Cell-Operated Auxiliaries 

Mode Type Truck 

Subgroup Accessory Load Reduction 

Responsible Parties 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 12

Target Parties 1, 2, 3, 4, 6, 7

Target GHGs CO2

Strategy Type Technology 

Practice Goals 

Goal is to have all trucks participate. The reductions in modal GHG 

emissions and energy use in 2025 would be 5.49% and 5.66%, 

respectively. 

Developmental Status N 

Practice Summary Fuel cells are an emerging technology for converting chemical energy in 

a fuel directly to electricity. The advantage of fuel cells over 

conventional engine and alternator technology is that they have 

substantially higher thermal efficiency. Among the barriers to practical 

use of fuel cells are the cost of precious materials used for their internal 

components and the need for conversion of readily available 

transportation fuels to a form that can be processed by the fuel cell. 

The use of fuel cells coupled with electrically operated auxiliaries could 

be available in the market by 2012. 

Potential Reductions in 

Modal GHG Emissions 

5.49% 

Potential Reduction in 

Modal Energy Use 

5.66% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information The estimated incremental capital cost is $1,500. 

Benefits and Drawbacks This practice has high thermal efficiency, but further R & D is needed 

in order to reduce cost. 
185

Appendix A.32 Best Practice 1-32: Truck Driver Training Program 

This best practice is assessed qualitatively. Table A-32 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table A-32. Simplified Summary Table for Best Practice 1-32, Truck Driver Training Program 

Attribute Description 

Practice Name Truck Driver Training Program 

Mode Type Truck 

Subgroup Modifications in Driver Operational Practice 

Responsible Parties 1, 2, 5

Target Parties 1, 2, 5, 6

Target GHGs CO2

Strategy Type Operation 

Practice Goals 

Goal is to have all trucks participate. The reductions in modal GHG 

emissions and energy use in 2025 would be 3.10% and 3.19%, 

respectively. 

Developmental Status C 

Practice Summary The behavior of truck drivers can significantly impact fuel efficiency. 

Drivers can be encouraged to modify behaviors that unnecessarily 

increase fuel use via training programs that aim to convey better skills 

and habits. Furthermore, driver performance can be monitored and 

incentives can be provided to reward preferred behaviors. 

Potential Reductions in 

Modal GHG Emissions 

3.10% 

Potential Reduction in 

Modal Energy Use 

3.19% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information N/A 

Benefits and Drawbacks Driver training can reduce fuel consumption significantly. 

 
186

Appendix A.33 Best Practice 1-33: B20 Biodiesel Fuel for Trucks 

This best practice is assessed quantitatively. Table A-33 summarizes the assessment 

results. This table is in the format of the standardized reporting table for quantitative results. 

The basis of the quantitative estimates is explained.

A. Estimate of total number of vehicles or devices: 

(a) 2003 Results: It is estimated that there were 7.9 million trucks in 2003.3

(b) 2025 Results: Since total truck number is estimated to grow by 67% from 2003 to 

2025, which is explained in Appendix A.1.A, there will be 13.2 

million trucks in 2025. 

B. Estimate of annual transport activity for the mode: 

Annual transport activity for the mode is explained in Appendix A.1.B. 

C. Estimate of annual transport activity to which a practice is applicable: 

Annual transport activity to which this practice is applicable is the same as the transport 

activity for the whole mode, which is explained in Appendix A.1.B. 

D. Estimate of annual GHG emissions reductions: 

 (a) Assumption: i. The net life-cycle CO2 emissions reduction of B20 biodiesel is 

about 0.0069 tons CO2 eq. per 106 BTU, which is estimated in 

Appendix F.2.3.61 

ii. Biodiesel industry was estimated that it has the potential to 

produce 1.7 billion gallons of B100 biodiesel in 2003, 3.5 billion 

gallons of B100 biodiesel in 2015, and 10 billion gallons of 

B100 biodiesel in 2030.63,64 Thus, the estimated production of 

B100 biodiesel in 2025 is 7.8 billion gallons. 
187

Table A-33. Standardized Reporting Table for Best Practice 1-33, B20 Biodiesel Fuel for 

Trucksa

Characteristics of the Practice Description 

Practice Name B20 Biodiesel Fuel for Trucks 

Mode Type Truck 

Subgroup Alternative Fuels 

Responsible Parties 1, 2, 4, 5, 6, 12, 14, 16, 18, 19, 20, 21, 22

Target Parties 1, 2, 4, 5, 6, 7

Target GHGs CO2

Strategy Type Technology 

Practice Goals 

Goal is to have all trucks participate. 

The reductions in modal GHG emissions 

and energy use in 2025 would 4.27% 

(30.8 ×106

 tons of CO2 eq.) and -4.25% 

(-370 ×1012 Btu), respectively. 

Developmental Status C 

Practice Summary The life-cycle CO2 emissions coefficient 

of B20 biodiesel decreases by 0.0069 tons 

CO2 eq. per 106

 BTU compared to that of 

petroleum diesel. 

Emissions, Energy Use, and Refrigerant Use Unit Value 

Annual Transport Activity for the Mode (ATAM) 109 ton-miles/year 2,098 

Annual Transport Activity to Which a Practice Is 

Applicable (ATAP) 109

 ton-miles/year 2,098 

Annual GHG Emissions Reductions(AGR) 106 ton CO2 eq./year 30.8 

Annual Energy Use Reduction (AER) 1012 BTU /year -370 

Annual Refrigerant Use Reduction (ARR) lbs/year N/A 

Unit GHG Emissions Reductions (UGER) 10-3 lb CO2 eq./ton-mile 29 

Unit Energy Use Reduction (UER) BTU /ton-mile -176 

Unit Refrigerant Use Reduction (URR) lbs/ton-mile N/A 

Practice Costs 

Capital Cost I 106 USD ($) N/A 

Discount Rate I % 10% 

Technical Lifetime of Technology (L) years N/A 

Fixed Charge Factor (a) year-1 N/A 

Annual O & M Cost (AOM) $106 /year N/A 

Annualized Cost (AC) $106 /year 3,340

Annual Energy Cost Saving (AECS) $106 /year 0 

Annual Refrigerant Cost Saving (ARCS) $106 /year N/A 

Net Savings (NS) $106 /year -3,340 

Net Savings per Unit of GHG Emissions Reductions 

(NSGR) $/ton CO2 eq. -108 

Net Savings per Unit of Energy Use Reduction (NSER) $/106 BTU N/Ab

Net Savings per Unit of Refrigerant Use Reduction 

(NSRR) $/lb N/A 

Simple Payback Period (SPP) years N/Ac

a

 These assessments are based on the assumptions that these best practices reach their potential 

maximum market shares in 2025. 

b

 This practice has no energy use reduction due to an increase in energy use, and it has no net saving 

due to high annualized cost and no energy cost saving. 
188

c

 There is no pay-back period for this best practice because there is no net saving. 

 iii. The estimated heating value of B100 biodiesel is 126,789 

BTU/gallon, and the estimated heating value of petroleum diesel is 

138,690 BTU/gallon.131-132 Thus, the estimated heating value of 

B20 biodiesel is 136,310 BTU/gallon. 

iv. The truck mode consumed 4.6×1015 BTU of diesel fuel in 

2003.2,3 The rail mode consumed 0.531×1015 BTU diesel in 

2003.3 The water mode consumed 0.385×1015 BTU distillate fuel 

oil in 2003.1,3 

v. The potential market share of B20 biodiesel for the truck mode 

is estimated to be 51.2% in 2025 based on the potential maximum 

production capacity of biodiesel, which is estimated as 7.8 billion 

gallons in 2025, and the distribution ratio among the truck, rail and 

water modes. 

 (b) Calculation: i. Energy use for the truck mode in 2025 is estimated to be 

8.7×1015 BTU. 

ii. Maximum B20 biodiesel production capacity for the truck mode 

in 2003 is estimated to be 0.97×1015 BTU. 

iii. Maximum B20 biodiesel production capacity for the truck 

mode in 2025 is estimated to be 4.45×1015 BTU. 

 8.7 10 BTU 51.2% 4.45 10 BTU 15 15 × × = ×

iii. The annual GHG emissions reductions are estimated to be 

30.8×106

 tons CO2 eq. in 2025. 

30.8 10 tons CO eq. 10 BTU

0.0069 CO eq. 4.45 10 BTU 2

6

6

15 2

× × = ×

(c) Results: The annual GHG emissions reductions are estimated to be 

30.8×106

 tons CO2 eq. in 2025. 
189

E. Estimate of annual energy use reduction: 

i.. Energy use reduction based on life cycle inventory is estimated to be -8.3%.61 

ii. Energy use reduction based on life cycle inventory in 2025 is estimated to be -3.7×1014 

BTU 

 8.3%. 4.45 10 BTU 3.7 10 BTU 15 14 − × × = − ×

F. Estimate of unit GHG emissions reductions: 

ton mile

0.029 lb CO eq.

ton

2,000 lbs . 2097 10 ton miles

30.8 10 tons CO eq 2

9

2

6

− =















×















× −

×

G. Estimate of unit energy use reduction: 

( )

ton mile

176.4 BTU . 2097 10 ton miles3.7 10 10 BTU 9

8 6

−

− = 















× −

− ×

H. Estimate of capital cost 

(Not available) 

I. Estimate of annual O & M cost

(Not available) 

J. Estimate of annualized cost: 

i. The average fuel cost of B100 Biodiesel in April 2005 is estimated to be $22.2 per 106

BTU.137 

ii. Diesel fuel price in 2025 is the same as the price of the second season of 2005, which 

is $18.5/106 BTU.114 

iii. Thus, B20 biodiesel fuel price is estimated to be $19.21/106 BTU, which is $0.75/106

BTU higher than the price of diesel fuel. 

iv. Annualized cost is estimated to be $3.34 ×109

. 
190

15 9

6 4.45 10 BTU $3.34 10

10 BTU

$0.75

× × = ×

K. Estimate of energy cost reduction: 

 (No energy cost reduction) 

L. Estimate of net savings: 

9 9 $0 − $3.34×10 = −$3.34×10

M. Estimate of net savings per unit of GHG emissions reductions: 

ton CO eq.

$108.4

30.8 10 tons CO eq.

$3.34 10

2 2

6

9 − = ×

− ×

N. Estimate of net savings per unit of energy use reduction: 

 (Not available: This practice has no energy use reduction due to an increase in energy 

use, and it has no net saving due to high annualized cost and no energy cost saving). 

O. Estimate of simple payback period: 

 (Not available: there is no pay-back period for this practice because there is no net 

saving). 
191

APPENDIX B. DETAILS OF INPUT DATA, ASSUMPTIONS, AND ESTIMATION 

RESULTS FOR RAIL MODE BEST PRACTICES 

This appendix is additional descriptive information for the best practices in Chapter 5, 

including the standardized reporting tables, if their corresponding best practices can be assessed 

quantitatively, or the simplified summary tables, if their corresponding best practices are 

assessed qualitatively. For those assessed quantitatively, the methods for the estimation of data 

in the standardized reporting tables are also described. 

Appendix B.1 Best Practice 2-1: Combined Diesel Powered Heating System and Auto 

Engine Start/Stop System 

This best practice is assessed quantitatively. Table B-1 summarizes the assessment 

results. This table is in the format of the standardized reporting table for quantitative results. 

The basis of the quantitative estimates is explained. 

A. Estimate of total number of vehicles or devices: 

(a) Assumption: Annual per-locomotive energy use in 2025 is the same as annual 

per-locomotive energy use in 2003. 

(b) Calculation: i. It is estimated that there were 20,774 Class I locomotives in 

2003.3 

ii. Since per-locomotive energy use is the same and modal energy 

use is estimated to grow by 49% from 2003 to 2025,4

 locomotive 

number increases by 49% from 2003 to 2025. 

20,774 × (1+ 49%) = 30,965

(c) Results: There will be 30,965 Class I locomotives in 2025. 

B. Estimate of annual transport activity for the mode: 

(a) Assumption: The growth rate of total transport activity is the same as the growth 

rate of energy use for the rail mode. 

(b) 2003 Results: It is estimated that there were 1,551 ×109

 ton-miles in 2003.3 
192

Table B-1. Standardized Reporting Table for Best Practice 2-1, Combined Diesel Powered 

Heating System and Auto Engine Start/Stop Systema

Characteristics of the Practice Description 

Practice Name 

Combined Diesel Powered Heating 

System and Auto Engine Start/Stop 

System 

Mode Type Rail 

Subgroup Anti-idling 

Responsible Parties 26, 27, 28, 35, 36, 37

Target Parties 11, 13

Target GHGs CO2

Strategy Type Technology 

Practice Goals 

Goal is to have all long-haul and 

switching locomotives participate. The 

reductions in modal GHG emissions and 

energy use in 2025 would both be 3.62% 

(2.32 ×106

 tons of CO2 eq. and 28.7 ×1012

Btu, respectively). 

Developmental Status P 

Practice Summary Diesel powered heating systems keep the 

engine block temperature above 100 o

F. 

Such systems utilize waste heat from a 

small diesel engine to heat the main 

engine and to generate electricity using by 

an alternator. An auto engine start/stop 

system can shutdown and restart both 

long-haul and switching locomotive 

engines automatically, based on a 

preprogrammed set of values. Both of 

these systems can be used simultaneously 

to shut down the engine when not needed 

while also keep the engine warm in 

preparation for a restart and while 

maintaining batteries in a ready status. 

Emissions, Energy Use, and Refrigerant Use Unit Value 

Annual Transport Activity for the Mode (ATAM) 109 ton-miles/year 2,312 

Annual Transport Activity to Which a Practice Is 

Applicable (ATAP) 109

 ton-miles/year 2,312 

Annual GHG Emissions Reductions(AGR) 106 ton CO2 eq./year 2.32 

Annual Energy Use Reduction (AER) 1012 BTU /year 28.7 

Annual Refrigerant Use Reduction (ARR) lbs/year N/A 

Unit GHG Emissions Reductions (UGER) 10-3 lb CO2 eq./ton-mile 2.0 

Unit Energy Use Reduction (UER) BTU /ton-mile 12.4 

Unit Refrigerant Use Reduction (URR) lbs/ton-mile N/A 

Practice Costs 

Capital Cost (C) 106 USD ($) 1,100 

Discount Rate (r) % 10% 

Technical Lifetime of Technology (L) years 15 

Fixed Charge Factor (a) year-1 0.131 
193

Annual O & M Cost (AOM) $106 /year N/A 

Annualized Cost (AC) $106 /year 144.0

Annual Energy Cost Saving (AECS) $106 /year 531.4 

Annual Refrigerant Cost Saving (ARCS) $106 /year N/A 

Net Savings (NS) $106 /year 387.4 

Net Savings per Unit of GHG Emissions Reductions 

(NSGR) $/ton CO2 eq. 167 

Net Savings per Unit of Energy Use Reduction (NSER) $/106 BTU 13.5 

Net Savings per Unit of Refrigerant Use Reduction 

(NSRR) $/lb N/A 

Simple Payback Period (SPP) years 2.1 a

 These assessments are based on the assumptions that these best practices reach their potential 

maximum market shares in 2025. 

(c) 2025 Results: Since total energy use for the rail mode is estimated to grow by 

49% from 2003 to 2025,4

 there will be 2,312 ×109 ton-miles in 

2025. 

C. Estimate of annual transport activity to which a practice is applicable: 

Annual transport activity to which this practice is applicable is the same as the total 

ton-miles of this mode, which is explained in Appendix B.1.B. 

D. Estimate of annual GHG emissions reductions: 

(a) 

Assumption: i. Total GHG emissions reductions are due to energy use reduction. 

ii. Long-haul Class I locomotives work 330 days per year and 55% 

of time is at idle.67 Switchers work 330 days per year72 and 

75% of time of switchers is at idle.67 55% of idle time is used 

for all locomotive for the estimation in order to simplify the 

calculation. 

iii. Idle fuel use for a Class I locomotive is estimated to be 3 gallon 

per hour.138 

iv. This best practice is applicable to both long-haul locomotives 

and switchers. 

ix. This practice can reduce idle time by 64% if 55% of time is at 

idle,68 and reduce fuel use at idle by 80%.67 
194

(b) Calculation: i. Class I locomotives consume fuel at idle in 2025 is estimated to 

be 5.61×1013 BTU. 

 

5.61 10 BTU

gallon

138690 BTU

24 hrs 330 days 55%

hr

3 gallon 30965

13 = ×

















× × × × ×

ii. Energy use reduction for adopting this practice in 2025 is 

estimated to be 2.87×1013 BTU. 

 5.61 10 BTU 64% 80% 2.87 10 BTU 13 13 × × × = ×

iii. Total GHG emissions reductions in 2025 due to fuel use 

reduction are estimated to be 2.32×106

 tons CO2 eq. 

2.32 10 tons CO eq. 10 BTU

0.0808 tons CO eq. 2.87 10 BTU 2

6

6

13 2 = × 















× ×

(c) Results: The annual GHG emissions reductions are estimated to be 2.32×106

tons CO2 eq. in 2025. 

E. Estimate of annual energy use reduction: 

The estimated annual energy use reduction in 2025 is 2.87×107 (106 BTU), which is 

estimated in Appendix B.1.D. 

F. Estimate of unit GHG emissions reductions: 

ton mile

0.002 lb CO eq.

ton

2,000 lbs . 2312 10 ton miles

2.32 10 tons CO eq 2

9

2

6

− =















×















× −

×

G. Estimate of unit energy use reduction: 

( )

ton mile

12.4 BTU . 2312 10 ton miles2.87 10 10 BTU

9

7 6

− = 















× −

×
195

H. Estimate of capital cost 

The estimated capital cost for this practice is $35,500 per locomotive.68 Total capital 

costs for all locomotives in 2025 is estimated to be $1.1 ×109. 

9 9 30,965 locomotives $1.1 10 $1.1 10

truck

$35,500

× = × = ×

I. Estimate of annual O & M cost

(Not available) 

J. Estimate of annualized cost: 

i. The life-time of this practice is estimated to be 15 years. 

ii. Fixed charge factor is estimated to be 0.131. 

( )

( )

0.131

1 0.1

1

1 Fixed ch arg e factor a

15

i 1 i

=

































+

=

∑=

iii. Annualized cost is estimated to be $144.0 ×106. 

( ) 9 6 $1.12×10 × 0.131 = $144.0×10

K. Estimate of energy cost reduction: 

(a) Assumption: Diesel fuel price in 2025 is the same as the price of the second 

season of 2005, which is $2.56/gallon ( = $18.5/106

 BTU).114 

(b) Calculation: The estimated energy cost reduction in 2025 is $531.4 ×106. 

( ) 6

6

7 6 $531.4 10

10 BTU

$18.5 2.87×10 10 BTU ×× = ×

(c) Results: The estimated energy cost reduction in 2025 is $531.4 ×106

. 

L. Estimate of net savings: 

6 6 6 $531.4×10 − $144.0×10 = $387.4×10

M. Estimate of net savings per unit of GHG emissions reductions: 
196

ton CO eq.

$167.0

2.32 10 tons CO eq.

$0.387 10

2 2

6

9

= ×

×

N. Estimate of net savings per unit of energy use reduction: 

10 BTU

$13.5

28.7 10 BTU

$0.387 10

12 6

9

= ×

×

O. Estimate of simple payback period: 

( ) 2.1 years $0.531 10

$1.1 10

9

9

= ×

×
197

Appendix B.2 Best Practice 2-2: Battery-Diesel Hybrid Switching Locomotive 

This best practice is assessed quantitatively. Table B-2 summarizes the assessment 

results. This table is in the format of the standardized reporting table for quantitative results. 

The basis of the quantitative estimates is explained.

A. Estimate of total number of vehicles or devices: 

(a) Assumptions: i. Assuming that the national ratio of yard switchers to total 

locomotives is the same as the ratio for Union Pacific (UP), the 

largest railroad company in the U.S., approximately 71% of 

locomotives are long-haul.125 

ii. The remainder (29% of locomotives) are switchers. 

iii. The growth rate of total switcher number is the same as the 

growth rate of total locomotive number for the rail mode. 

(b) Calculations: i. It is estimated that there were 20,774 Class I locomotives in 

2003.3

 

ii. It is estimated that there were 6,000 switching locomotives in 

2003. 

 ( ) 20,774× 29% = 6,000

(c) Results Since total locomotive number for this mode is estimated to grow 

by 49% from 2003 to 2025, which is explained in Appendix B.1.A, 

there will be 8,860 switchers in 2025. 

B. Estimate of annual transport activity for the mode: 

Annual transport activity for the rail mode is explained in Appendix B.1.B. 

C. Estimate of annual transport activity to which a practice is applicable: 

Annual transport activity to which this practice is applicable is the same as the total 

ton-miles of this mode, which is explained in Appendix B.1.C. 
198

Table B-2. Standardized Reporting Table for Best Practice 2-2, Battery-Diesel Hybrid 

Switching Locomotive a

Characteristics of the Practice Description 

Practice Name Battery-Diesel Hybrid Switching 

Locomotive 

Mode Type Rail 

Subgroup Anti-Idling 

Responsible Parties 26, 27

Target Parties 11

Target GHGs CO2

Strategy Type Technology 

Practice Goals 

Goal is to have all switching locomotives 

participate. The reductions in modal 

GHG emissions and energy use in 2025 

would both be 1.75% (1.12 ×106 tons of 

CO2 eq. and 13.8 ×1012 Btu, respectively). 

Developmental Status C 

Practice Summary Battery-diesel hybrid switchers are 

commercially available locomotives that 

can replace traditional switching 

locomotives. Traditional switchers 

typically have 2,000 hp diesel engines. 

Battery-diesel hybrid switchers include a 

small diesel engine (e.g., 125 to 300 hp) 

and large (60,000 lbs) lead-acid batteries. 

This small diesel engine is used to charge 

batteries that maintain batteries in a ready 

status during periods of locomotive 

non-use. At full load, the batteries 

account for 95% of the horsepower and 

the small diesel engine accounts for 

another 5%. This hybrid switcher also 

has an auto start/stop system that contains 

a microprocessor to automatically shut 

down the small diesel engine during 

periods of locomotive non-use or when 

the batteries are fully charged based on 

battery voltage values. 

Emissions, Energy Use, and Refrigerant Use Unit Value 

Annual Transport Activity for the Mode (ATAM) 109 ton-miles/year 2,312 

Annual Transport Activity to Which a Practice Is 

Applicable (ATAP) 109

 ton-miles/year 2,312 

Annual GHG Emissions Reductions(AGR) 106 ton CO2 eq./year 1.12 

Annual Energy Use Reduction (AER) 1012 BTU /year 13.8 

Annual Refrigerant Use Reduction (ARR) lbs/year N/A 

Unit GHG Emissions Reductions (UGER) 10-3 lb CO2 eq./ton-mile 1.0 

Unit Energy Use Reduction (UER) BTU /ton-mile 6.0 

Unit Refrigerant Use Reduction (URR) lbs/ton-mile N/A 

Practice Costs 
199

Capital Cost (C) 106 USD ($) 1401.4 

Discount Rate (r) % 10% 

Technical Lifetime of Technology (L) years 15 

Fixed Charge Factor (a) year-1 0.131 

Annual O & M Cost (AOM) $106 /year N/A 

Annualized Cost (AC) $106 /year 183.6

Annual Energy Cost Saving (AECS) $106 /year 255.8 

Annual Refrigerant Cost Saving (ARCS) $106 /year N/A 

Net Savings (NS) $106 /year 72.2 

Net Savings per Unit of GHG Emissions Reductions 

(NSGR) $/ton CO2 eq. 64.5 

Net Savings per Unit of Energy Use Reduction (NSER) $/106 BTU 5.2 

Net Savings per Unit of Refrigerant Use Reduction 

(NSRR) $/lb N/A 

Simple Payback Period (SPP) years 5.5 a

 These assessments are based on the assumptions that these best practices reach their potential 

maximum market shares in 2025. 

D. Estimate of annual GHG emissions reductions: 

(a) 

Assumption: i. Total GHG emissions reductions are due to energy use reduction. 

ii. Switchers work 330 days per year72 and 75% of time of switchers 

is at idle.67 

iii. Assuming that the national ratio of yard switchers to total 

locomotives is the same as the ratio for Union Pacific (UP), the 

largest railroad company in the U.S., approximately 71% of 

locomotives are long-haul.125 The remainder are switchers. 

iv. This practice is applicable to switchers only. 

v. Assuming that the national ratio of yard switchers to total 

locomotives is the same as the ratio for Union Pacific (UP), it is 

estimated that switchers account for only 5% of total locomotive 

fuel use.117 

vi. Total fuel use for this mode in 2003 is 3.826 × 109 gallons.3 

vii. This practice can reduce energy use for switchers by 35%.71 

viii. Total GHG emissions for the rail mode is estimated to grow by 

49% from 2003 to 2025, which is explained in Section 1.2. 

(b) Calculation: i. Energy use for switchers in 2025 is estimated to be 3.95×1013
200

BTU. 

 5% ( ) 1 49% 3.95 10 BTU

gallon

138690 BTU

3.826 109 13 = × 















× × × × +

ii. Energy use reduction in 2025 for adopting this practice is 

estimated to be 1.38×1013 BTU. 

 3.95 10 BTU 35% 1.38 10 BTU 13 13 × × = ×

iii. Total GHG emissions reductions due to energy use reduction are 

estimated to be 1.12×106 tons CO2 eq. in 2025. 

1.12 10 tons CO eq. 10 BTU

0.0808 tons CO eq. 1.38 10 BTU 2

6

6

13 2 = × 















× ×

(c) Results: The annual GHG emissions reductions are estimated to be 1.12×106

tons CO2 eq. in 2025. 

E. Estimate of annual energy use reduction: 

The estimated annual energy use reduction in 2025 is 1.38×107 (106 BTU) while it is 

estimated in Appendix B.2.D. 

F. Estimate of unit GHG emissions reductions: 

ton mile

0.001 lb CO eq.

ton

2,000 lbs . 2312 10 ton miles

1.12 10 tons CO eq 2

9

2

6

− =















× 















× −

×

G. Estimate of unit energy use reduction: 

( )

ton mile

6.0 BTU

2312 10 ton miles

1.38 10 10 BTU

9

7 6

− =















× −

×

H. Estimate of capital cost 
201

(a) Assumptions: i. A switcher consumes 348 gallons of fuel per day.72 

ii. A switcher works 330 days per day.72 

iii. The working loads of switchers are 50%. 72 

iv. Only a fraction of switchers are in use. 

v. The capital cost of a battery-diesel hybrid switcher is estimated 

to be $283,000.71 

(b) Calculations: i. Energy use for switchers in 2025 is estimated to be 3.95×1013

BTU, which is estimated in Appendix B.2.D. 

ii. It is estimated that there were 4,950 switching locomotives in 

use in 2025. 

 ( ) 4,950

gallon

138690 BTU

348 gallons 330 days 50%

3.95 10 BTU 13

=

















× × ×

×

iii. For this estimation, 4,950 is the number of switchers used for 

estimating total capital cost because the switchers that are 

considered to be replaced by hybrid switchers are the switchers 

in use, not total switchers (total switchers are estimated to be 

8,860, which is estimated in Appendix B.2.A.). 

iv. Total capital cost in 2025 is estimated to be $1.401 × 109. 

9 4,950×$283,000 = $1.401×10

(c) Results Total capital cost in 2025 is estimated to be $1.401 × 109

. 

I. Estimate of annual O & M cost

(Not available) 

J. Estimate of annualized cost: 

i. The life-time of this practice is estimated to be 15 years. 

ii. Fixed charge factor is estimated to be 0.131. 
202

( )

( )

0.131

1 0.1

1

1 Fixed ch arg e factor a

15

i 1 i

=

































+

=

∑=

iii. Annualized cost is estimated to be $183.6 × 106

. 

( ) 9 6 $1.40×10 × 0.131 = $183.6×10

K. Estimate of energy cost reduction: 

(a) Assumption: Diesel fuel price in 2025 is the same as the price of the second 

season of 2005, which is $2.56/gallon ( = $18.5/106 BTU).114 

(b) Calculation: The estimated energy cost reduction in 2025 is $255.8 × 106

. 

( ) 6

6

7 6 $255.8 10

10 BTU

$18.5 1.38×10 10 BTU ×× = ×

(c) Results: The estimated energy cost reduction in 2025 is $255.8 × 106. 

L. Estimate of net savings: 

6 6 6 $255.8×10 − $183.6×10 = $72.2×10

M. Estimate of net savings per unit of GHG emissions reductions: 

ton CO eq.

$64.5

1.12 10 tons CO eq.

$72.2 10

2 2

6

6

= ×

×

N. Estimate of net savings per unit of energy use reduction: 

10 BTU

$5.2

13.8 10 BTU

$72.2 10

12 6

6

= ×

×

O. Estimate of simple payback period: 

( ) 5.5 years $255.8 10

$1.40 10

6

9

= ×

×
203

Appendix B.3 Best Practice 2-3: Plug-in Unit 

This best practice is assessed quantitatively. Table B-3 summarizes the assessment 

results. This table is in the format of the standardized reporting table for quantitative results. 

The basis of the quantitative estimates is explained.

A. Estimate of total number of vehicles or devices: 

Total number of switchers is explained in Appendix B.2.A. 

B. Estimate of annual transport activity for the mode: 

Annual transport activity for the mode is explained in Appendix B.1.B. 

C. Estimate of annual transport activity to which a practice is applicable: 

Annual transport activity to which this practice is applicable is explained in Appendix 

B.1.C. 

D. Estimate of annual GHG emissions reductions: 

 (a) Assumption: i. Total GHG emissions reductions are that GHG emissions 

reductions due to energy use reduction minus GHG emissions 

due to electricity use for operating this practice. 

iii. Switchers work 330 days per year72 and 75% of time of 

switchers is at idle.67 

iv. Plug-in units consume 30 kW of electricity.134 

vi. It is estimated that there will be 4,950 switching locomotives in 

use in 2025, which is estimated in Appendix B.2.H. 

iii. GHG emissions coefficient for diesel fuel is 0.0808 tons CO2

eq. per 106 BTU.1

vi. GHG emissions coefficient for electricity is 0.0007 tons CO2

eq. per kWh.108 
204

Table B-3. Standardized Reporting Table for Best Practice 2-3, Plug-In Unit a

Characteristics of the Practice Description 

Practice Name Plug-In Unit 

Mode Type Rail 

Subgroup Anti-Idling 

Responsible Parties 26, 27

Target Parties 11

Target GHGs CO2

Strategy Type Technology 

Practice Goals 

Goal is to have all switching locomotives 

participate. The reductions in modal 

GHG emissions and energy use in 2025 

would be 0.58% (0.37 ×106

 tons of CO2 

eq.) and 0.44% (3.5 ×1012 Btu), 

respectively. 

Developmental Status C 

Practice Summary Plug-in units are commercially available 

systems that can avoid the need for idling 

of switcher engines while switchers are 

parked in switching yards. These 

systems, which require both on-board and 

off-board components, enable locomotive 

drivers to switch off their diesel engines 

by plugging a locomotive into an external 

electrical power source. These systems 

can use electricity powered systems to 

supply heat, circulate and heat coolant 

and oil, and keep batteries charged. 

Emissions, Energy Use, and Refrigerant Use Unit Value 

Annual Transport Activity for the Mode (ATAM) 109 ton-miles/year 2,312 

Annual Transport Activity to Which a Practice Is 

Applicable (ATAP) 109

 ton-miles/year 2,312 

Annual GHG Emissions Reductions(AGR) 106 ton CO2 eq./year 0.37 

Annual Energy Use Reduction (AER) 1012 BTU /year 3.5 

Annual Refrigerant Use Reduction (ARR) lbs/year N/A 

Unit GHG Emissions Reductions (UGER) 10-3 lb CO2 eq./ton-mile 0.3 

Unit Energy Use Reduction (UER) BTU /ton-mile 1.5 

Unit Refrigerant Use Reduction (URR) lbs/ton-mile N/A 

Practice Costs 

Capital Cost (C) 106 USD ($) 118.8 

Discount Rate (r) % 10% 

Technical Lifetime of Technology (L) years 15 

Fixed Charge Factor (a) year-1 0.131 

Annual O & M Cost (AOM) $106 /year 75.6 

Annualized Cost (AC) $106 /year 91.2

Annual Energy Cost Saving (AECS) $106 /year 225.7 

Annual Refrigerant Cost Saving (ARCS) $106 /year N/A 

Net Savings (NS) $106 /year 134.6 

Net Savings per Unit of GHG Emissions Reductions $/ton CO2 eq. 363.6 
205

(NSGR) 

Net Savings per Unit of Energy Use Reduction (NSER) $/106 BTU 38.4 

Net Savings per Unit of Refrigerant Use Reduction 

(NSRR) $/lb N/A 

Simple Payback Period (SPP) years 0.79 a

 These assessments are based on the assumptions that these best practices reach their potential 

maximum market shares in 2025. 

(b) Calculation: i. Energy use for switchers in 2025 is estimated to be 3.95×1013

BTU, which is estimated in Appendix B.2.D. 

ii. Diesel fuel use reduction in 2025 for adopting this practice, 

which reduce idle time (75% of time), is estimated to be 

1.22×1013 BTU. 

 

1.22 10 BTU

330 days 24 hrs 75% 4,950

gallon

138,690 BTU

hr

3 gallons

13 = ×

× × × × ×

iii. GHG emissions reductions due to diesel fuel use reduction are 

estimated to be 0.986×106

 tons CO2 eq. in 2025. 

 

0.986 10 tons CO eq.

10 BTU

0.0808 tons CO eq. 12.2 10 BTU

2

6

6

12 2

= ×

















× ×

iv. Electricity needed for plug-in units for switchers at idle is 

estimated to be 8.82×108 kWh. 

 

8.82 10 kWh

30 kW 330 days 24 hrs 75% 4,950

8 = ×

× × × × 

v. GHG emissions due to electricity use for this practice are 

estimated to be 0.617 ×106

 tons CO2 eq. in 2025. 
206

 

0.617 10 tons CO eq.

kWh

0.0007 tons CO eq. 8.82 10 kWh

2

6

8 2

= ×

















× ×

v. Total GHG emissions reductions are estimated to be 0.37×106

tons CO2 eq. in 2025. 

(0.986 0.617) 10 tons CO eq. 0.369 10 tons CO eq. 2

6

2

6 − × = ×

(c) Results: The annual GHG emissions reductions are estimated to be 

0.37×106

 tons CO2 eq. in 2025. 

E. Estimate of annual energy use reduction: 

(a) Assumption: i. Total energy use reduction is that energy use reduction minuses 

energy for producing electricity for operating this practice. 

ii. 1 kWh is equal to 3,412 BTU. 

iii. The ratio of primary energy input to electricity output is 

estimated to be 2.89 based on total electricity generated and 

total primary energy consumed in the U.S. in 2005.133

(b) Calculation: i. Diesel fuel use reduction in 2025 for adopting this practice is 

estimated to be 1.22×1013 BTU, which is estimated in Appendix 

B.3.D. 

ii. Electricity needed for plug-in units for switchers at idle in 2025 

is estimated to be 8.82×108

 kWh, which is equal to 3.01×1012

BTU. 

 

8.82 10 kWh

30 kW 330 days 24 hrs 75% 4,950

8 = ×

× × × ×

8.82 10 kWh 3,412 BTU 3.01 10 BTU 8 12 × × = ×

iii. Primary energy needed for producing electricity in order to 

operate this practice is estimated to be 8.70×1012 BTU. 
207

 3.01 10 BTU 2.89 8.70 10 BTU 12 12 × × = ×

iv. The estimated annual energy use reduction in 2025 is 3.50×106

(106 BTU). 

 12.2 10 BTU 8.70 10 BTU 3.50 10 (10 BTU) 12 12 6 6 × − × = ×

(c) Results: The estimated annual energy use reduction in 2025 is 3.50×106

(106 BTU), which is 8.86% of total energy use for switchers, or 

0.44% of total energy use for the rail mode. 

F. Estimate of unit GHG emissions reductions: 

ton mile

0.0003 lb CO eq.

ton

2,000 lbs . 2312 10 ton miles

0.37 10 tons CO eq 2

9

2

6

− =















× 















× −

×

G. Estimate of unit energy use reduction: 

( )

ton mile

1.51 BTU

2312 10 ton miles

3.50 10 10 BTU

9

6 6

− =















× −

×

H. Estimate of capital cost 

(a) Assumptions: i. There were 4,950 switching locomotives in use in 2025, which is 

estimated in Appendix B.2.H. 

ii. The capital cost of an on-board plug-in unit is estimated to be 

approximately $8,000.72 

iii. The capital cost for truck stop electrification infrastructure per 

parking space is estimated to be from $6,000 to $16,000.139 

iv. Assuming infrastructure cost for parking space for this practice 

is the same as the upper bound of the cost for truck stop 

electrification, total capital cost is estimated to be $24,000 per 

switcher. 
208

(b) Calculations: i. Total capital cost in 2025 is estimated to be $118.8 × 106. 

6 4,950×$14,000 = $118.8×10

(c) Results Total capital cost in 2025 is estimated to be $118.8 × 106

. 

I. Estimate of annual O & M cost

(a) Assumption: Electricity price for transportation in 2025 is the same as the price 

for transportation in 2005, which is $0.0857/kWh.140 

(b) Calculation: The estimated annual electricity cost in 2025 is $75.59 × 106. 

8 6 $75.59 10

kWh

$0.0857 8.82×10 kWh ×× = ×

(c) Results: The estimated annual electricity cost in 2025 is $75.59 × 106. 

J. Estimate of annualized cost: 

i. The life-time of this practice is estimated to be 15 years. 

ii. Fixed charge factor is estimated to be 0.131. 

( )

( )

0.131

1 0.1

1

1 Fixed ch arg e factor a

15

i 1 i

=

































+

=

∑=

iii. Annualized cost is estimated to be $91.15 × 106

. 

( ) 6 6 6 $118.8×10 × 0.131 + 75.59×10 = $91.15×10

K. Estimate of energy cost reduction: 

(a) Assumption: Diesel fuel price in 2025 is the same as the price of the second 

season of 2005, which is $2.56/gallon ( = $18.5/106

 BTU).114 

(b) Calculation: The estimated energy cost reduction in 2025 is $225.7 × 106. 

( ) 6

6

6 6 $225.7 10

10 BTU

$18.5 12.2×10 10 BTU ×× = ×
209

(c) Results: The estimated energy cost reduction in 2025 is $225.7 × 106. 

L. Estimate of net savings: 

6 6 6 $225.7×10 − $91.15×10 = $134.55×10

M. Estimate of net savings per unit of GHG emissions reductions: 

ton CO eq.

$363.6

0.37 10 tons CO eq.

$134.55 10

2 2

6

6

= ×

×

N. Estimate of net savings per unit of energy use reduction: 

10 BTU

$38.4

3.5 10 BTU

$134.55 10

12 6

6

= ×

×

O. Estimate of simple payback period: 

( ) 0.79 years $225.7 10 $75.6 10

$118.8 10

6 6

6

= × − ×

×
210

Appendix B.4 Best Practice 2-4: Light Weight Materials 

This best practice is assessed qualitatively. Table B-4 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table B-4. Simplified Summary Table for Best Practice 2-4, Light Weight Materials 

Attribute Description 

Practice Name Light Weight Materials 

Mode Type Rail 

Subgroup Weight Reduction 

Responsible Parties 26, 27

Target Parties 11, 12

Target GHGs CO2

Strategy Type Technology 

Practice Goals 

Goal is to have all Class I locomotives and railcars participate. The 

reductions in modal GHG emissions and energy use in 2025 would be 

both 4.76%. 

Developmental Status C 

Practice Summary The use of lighter-weight components to reduce the weight of 

locomotives and railcars has the potential to reduce fuel use. 

High-strength, lightweight components include aluminum, plastics, and 

others. Redesigns can also reduce railcar weight and reduce fuel use. 

Potential Reductions in 

Modal GHG Emissions 

4.76% 

Potential Reduction in 

Modal Energy Use 

4.76% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information N/A 

Benefits and Drawbacks Higher-capacity railcars that have better design and that use 

lightweight materials can carry more goods and also reduce energy 

use. However, current light-weight materials may be costly and may 

not have satisfactions at material characteristics, such as strength. 

Further research and development for advanced materials is needed. 
211

Appendix B.5 Best Practice 2-5: Lubrication Improvement 

This best practice is assessed qualitatively. Table B-5 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table B-5. Simplified Summary Table for Best Practice 2-5, Lubrication Improvement

Attribute Description 

Practice Name Lubrication Improvement 

Mode Type Rail 

Subgroup Rolling Resistance Improvement 

Responsible Parties 26, 27, 30

Target Parties 8, 9, 10, 11, 12

Target GHGs CO2

Strategy Type Technology 

Practice Goals Goal is to have all Class I locomotives participate. The reductions in 

modal GHG emissions and energy use in 2025 would be both 4.0%. 

Developmental Status P 

Practice Summary Some energy expended by the locomotive is lost to wheel-to-rail friction. 

Reductions in wheel-to-rail resistance can be made via improved 

lubrication. Efficient lubrication systems, such as top-of-rail 

lubrication systems, reduce wheel and rail wear and reduce fuel 

consumption. These systems can avoid wheel slippage by distributing 

a proper amount of lubricants on the rail, so as to reduce wheel-to-rail 

resistance without causing slippage. 

Potential Reductions in 

Modal GHG Emissions 

4.0% 

Potential Reduction in 

Modal Energy Use 

4.0% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information N/A 

Benefits and Drawbacks The reduction of fuel use depends on the grade and curvature of 

railroads. 
212

Appendix B.6 Best Practice 2-6: B20 Biodiesel Fuel for Locomotives 

This best practice is assessed quantitatively. Table B-6 summarizes the assessment 

results. This table is in the format of the standardized reporting table for quantitative results. 

The basis of the quantitative estimates is explained.

A. Estimate of total number of vehicles or devices: 

Total number of locomotives for the rail mode is explained in Appendix B.1.A. 

B. Estimate of annual transport activity for the mode: 

Annual transport activity for the rail mode is explained in Appendix B.1.B. 

C. Estimate of annual transport activity to which a practice is applicable: 

Annual transport activity to which this practice is applicable is explained in Appendix 

B.1.C. 

D. Estimate of annual GHG emissions reductions: 

 (a) Assumption: i. The net life-cycle CO2 emissions reduction of B20 biodiesel is 

about 0.0069 tons CO2 eq. per 106 BTU, which is estimated in 

Appendix F.2.3.61 

ii. Biodiesel industry was estimated to produce 1.7 billion gallons 

of B100 biodiesel in 2003, 3.5 billion gallons in 2015, and 10 

billion gallons in 2030.63,64 Thus, the estimated production of 

B100 biodiesel in 2025 is 7.8 billion gallons. 

iii. The estimated heating value of B100 biodiesel is 126,789 

BTU/gallon, and the estimated heating value of petroleum diesel 

is 138,690 BTU/gallon.132-133 Thus, the estimated heating 

value of B20 biodiesel is 136,310 BTU/gallon. 
213

Table B-6. Standardized Reporting Table for Best Practice 2-6, B20 Biodiesel Fuel for 

Locomotivesa

Characteristics of the Practice Description 

Practice Name B20 Biodiesel Fuel for Locomotives 

Mode Type Rail 

Subgroup Alternative Fuels 

Responsible Parties 23, 25, 26, 28, 29

Target Parties 8, 10

Target GHGs CO2

Strategy Type Technology 

Practice Goals 

Goal is to have all Class I Locomotives 

participate. The reductions in modal 

GHG emissions and energy use in 2025 

would be 5.50% (3.5 ×106

 tons of CO2 

eq.) and -5.31% (-42.3 ×1012 Btu), 

respectively. 

Developmental Status N 

Practice Summary The life-cycle CO2 emissions coefficient 

of B20 biodiesel decreases by 0.0069 tons 

CO2 eq. per 106

 BTU compared to that of 

petroleum diesel. 

Emissions, Energy Use, and Refrigerant Use Unit Value 

Annual Transport Activity for the Mode (ATAM) 109 ton-miles/year 2,312 

Annual Transport Activity to Which a Practice Is 

Applicable (ATAP) 109

 ton-miles/year 2,312 

Annual GHG Emissions Reductions(AGR) 106 ton CO2 eq./year 3.5 

Annual Energy Use Reduction (AER) 1012 BTU /year -42.3 

Annual Refrigerant Use Reduction (ARR) lbs/year N/A 

Unit GHG Emissions Reductions (UGER) 10-3 lb CO2 eq./ton-mile 3.0 

Unit Energy Use Reduction (UER) BTU /ton-mile 18.2 

Unit Refrigerant Use Reduction (URR) lbs/ton-mile N/A 

Practice Costs 

Capital Cost I 106 USD ($) N/A 

Discount Rate I % 10% 

Technical Lifetime of Technology (L) years N/A 

Fixed Charge Factor (a) year-1 N/A 

Annual O & M Cost (AOM) $106 /year N/A 

Annualized Cost (AC) $106 /year 382.5

Annual Energy Cost Saving (AECS) $106 /year 0 

Annual Refrigerant Cost Saving (ARCS) $106 /year N/A 

Net Savings (NS) $106 /year -382.5 

Net Savings per Unit of GHG Emissions Reductions 

(NSGR) $/ton CO2 eq. -108.7 

Net Savings per Unit of Energy Use Reduction (NSER) $/106 BTU N/Ab

Net Savings per Unit of Refrigerant Use Reduction 

(NSRR) $/lb N/A 

Simple Payback Period (SPP) years N/Ac

a

 These assessments are based on the assumptions that these best practices reach their potential 

maximum market shares in 2025. 
214

b

 This practice has no energy use reduction due to an increase in energy use, and it has no net saving 

due to high annualized cost and no energy cost saving. c

 There is no pay-back period for this best practice because there is no net saving. 

 iv. In 2003, the truck mode consumed 4.6×1015 BTU of diesel.2,3

The rail mode consumed 0.531×1015 BTU of diesel.3 The 

water mode consumed 0.385×1015 BTU of distillate fuel.1,3 

v. The potential market share of B20 biodiesel for the rail mode is 

estimated as 64.56% in 2025 based on the potential maximum 

production capacity of biodiesel, which is estimated as 7.8 

billion gallons in 2025, and the distribution ratio among the 

truck, rail and water modes. 

 (b) Calculation: i. Energy use for the rail mode in 2025 is estimated to be 0.79×1015

BTU. 

ii. Maximum B20 biodiesel production capacity for the rail mode 

in 2025 is estimated to be 0.51×1015 BTU. 

 0.79 10 BTU 64.56% 0.51 10 BTU 15 15 × × = ×

iii. The annual GHG emissions reductions are estimated to be 

3.52×106

 tons CO2 eq. in 2025. 

 3.52 10 tons CO eq. 10 BTU

0.0069 CO eq. 0.51 10 BTU 2

6

6

15 2

× × = ×

(c) Results: The annual GHG emissions reductions are estimated to be 

3.52×106

 tons CO2 eq. in 2025. 

E. Estimate of annual energy use reduction: 

i. Energy use reduction based on life cycle inventory is estimated to be -8.3%, which is 

estimated in Appendix A.33.E. 

ii. Energy use reduction based on life cycle inventory is estimated to be -4.2×1013 BTU 

 8.3%. 0.51 10 BTU 4.2 10 BTU 15 13 − × × = − ×
215

F. Estimate of unit GHG emissions reductions: 

ton mile

0.0030 lb CO eq.

ton

2,000 lbs . 2312 10 ton miles

3.52 10 tons CO eq 2

9

2

6

− =















×















× −

×

G. Estimate of unit energy use reduction: 

( )

ton mile

18.2 BTU . 2312 10 ton miles4.2 10 10 BTU 9

7 6

−

− = 















× −

− ×

H. Estimate of capital cost 

(Not available) 

I. Estimate of annual O & M cost

(Not available) 

J. Estimate of annualized cost: 

i. B20 biodiesel fuel price is estimated to be $0.75/106 BTU higher than the price of 

diesel fuel, which is estimated in Appendix A.33.J. 

ii. Annualized cost is estimated to be $382.5 ×106. 

15 6

6 0.51 10 BTU $382.5 10

10 BTU

$0.75

× × = ×

K. Estimate of energy cost reduction: 

 (No energy cost reduction) 

L. Estimate of net savings: 

6 6 $0 − $382.5×10 = −$382.5×10

M. Estimate of net savings per unit of GHG emissions reductions: 

ton CO eq.

$108.7

3.52 10 tons CO eq.

$382.5 10

2 2

6

6 − = ×

− ×
216

N. Estimate of net savings per unit of energy use reduction: 

 (Not available: This practice has no energy use reduction due to an increase in energy 

use, and it has no net saving due to high annualized cost and no energy cost saving). 

O. Estimate of simple payback period: 

 (Not available: there is no pay-back period for this practice because there is no net 

saving). 
217

APPENDIX C. DETAILS OF INPUT DATA, ASSUMPTIONS, AND ESTIMATION 

RESULTS FOR AIR MODE BEST PRACTICES 

This appendix is additional descriptive information for the best practices in Chapter 6, 

including the simplified summary tables that their corresponding best practices are assessed 

qualitatively. 

Appendix C.1 Best Practice 3-1: Surface Grooves 

This best practice is assessed qualitatively. Table C-1 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table C-1. Simplified Summary Table for Best Practice 3-1, Surface Grooves 

Attribute Description 

Practice Name Surface Grooves 

Mode Type Air 

Subgroup Aerodynamic Drag Reduction 

Responsible Parties 41, 42, 44

Target Parties 16, 17

Target GHGs CO2

Strategy Type Technology 

Practice Goals Goal is to have all aircrafts participate. The reductions in modal GHG 

emissions and energy use in 2025 would be both 1.60%. 

Developmental Status P 

Practice Summary Skin friction drag, also referred to as viscous drag, is caused by the 

contact of the air flow against the surface of the aircraft, and is impacted 

by the viscosity property of air. An approach that is undergoing testing 

is the use of an adhesive-backed film with micro-grooves that is placed 

on the exterior surfaces of the wings and the fuselage of the airplane. 

The series of microscopic grooves produces a drag-reducing surface. 

The reduction in skin friction drag results in a decrease in fuel use. 

Potential Reductions in 

Modal GHG Emissions 

1.60% 

Potential Reduction in 

Modal Energy Use 

1.60% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information N/A 

Benefits and Drawbacks The disadvantage of this practice is that the lifetime of the film with 

micro-grooves is only 2 to 3 years. Thus, research is needed to 

improve the durability of the materials for the film. 
218

Appendix C.2 Best Practice 3-2: Hybrid Laminar Flow Technology 

This best practice is assessed qualitatively. Table C-2 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table C-2. Simplified Summary Table for Best Practice 3-2, Hybrid Laminar Flow Technology

Attribute Description 

Practice Name Hybrid Laminar Flow Technology 

Mode Type Air 

Subgroup Aerodynamic Drag Reduction 

Responsible Parties 41, 42, 44

Target Parties 16, 17

Target GHGs CO2

Strategy Type Technology 

Practice Goals Goal is to have all aircrafts participate. The reductions in modal GHG 

emissions and energy use in 2025 would be both 6.00%. 

Developmental Status N 

Practice Summary Laminar flow is a smooth air flow moving across an airfoil without 

turbulence, but it is usually destroyed by turbulence induced because of 

interactions with wing surfaces, leading to skin friction. Furthermore, 

contamination on the aircraft surface, such as the accumulation of ice, 

insects or other debris, degrades laminar flow. A newly developed 

concept, hybrid laminar flow technology, integrates both passive and 

active approaches to maintain laminar flow. A passive device requires 

no energy for its operation. An active device requires a source of 

energy for its operation. 

Passive anti-contamination devices are used to prevent or minimize 

contamination. An example of a passive anti-contamination device is a 

Krueger flap. This flap has hinged droop surfaces on the leading edge 

of the wings that can be used for ice and insect-contamination 

prevention. 

An active approach, a suction system, is comprised of a multi-layer 

panel on a wing surface. The multi-layer panel includes a thin outer 

layer with fine pores and a thicker inner layer. The space between 

these two layers is divided into chambers. Air is sucked through the 

pores on the outer layer, and then is vented through ducts out of the 

aircraft. The ducts are located to avoid negative impact to the 

aerodynamic performance of the aircraft. The air suction process can 

reduce air flow turbulence to maintain laminar flow on the surface of a 

wing 

Potential Reductions in 

Modal GHG Emissions 

6.00% 

Potential Reduction in 

Modal Energy Use 

6.00% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information N/A 

Benefits and Drawbacks N/A 
219

Appendix C.3 Best Practice 3-3: Blended Winglet 

This best practice is assessed qualitatively. Table C-3 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table C-3. Simplified Summary Table for Best Practice 3-3, Blended Winglet 

Attribute Description 

Practice Name Blended Winglet 

Mode Type Air 

Subgroup Aerodynamic Drag Reduction 

Responsible Parties 41, 42

Target Parties 14, 16, 17

Target GHGs CO2

Strategy Type Technology 

Practice Goals Goal is to have all aircrafts participate. The reductions in modal GHG 

emissions and energy use in 2025 would be both 2.00%. 

Developmental Status C 

Practice Summary Lift-induced drag is due to the tip vortices produced by a lifting wing. 

A blended winglet is a commercially available wing-tip device that can 

reduce lift-induced drag. A winglet is an extension mounted at the tip 

of a wing. A blended winglet combines part of the wing tip with the 

winglet using a smooth blended shape that can decrease the tip vortex 

intensity. 

Potential Reductions in 

Modal GHG Emissions 

2.00% 

Potential Reduction in 

Modal Energy Use 

2.00% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information N/A 

Benefits and Drawbacks This practice increases the surface area of the wing of the aircraft, 

which could increase the viscous drag. The effect of additional 

viscous drag associated with the surface area increase is accounted for 

in the estimate given here. 
220

Appendix C.4 Best Practice 3-4: Spiroid Tip 

This best practice is assessed qualitatively. Table C-4 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table C-4. Simplified Summary Table for Best Practice 3-4, Spiroid Tip 

Attribute Description 

Practice Name Spiroid Tip 

Mode Type Air 

Subgroup Aerodynamic Drag Reduction 

Responsible Parties 41, 42

Target Parties 14, 16, 17

Target GHGs CO2

Strategy Type Technology 

Practice Goals Goal is to have all aircrafts participate. The reductions in modal GHG 

emissions and energy use in 2025 would be both 1.65%. 

Developmental Status C 

Practice Summary An alternative type of wing-tip device is a spiroid tip. This device has 

been pilot tested and, like blended winglets, is intended to reduce 

lift-induced drag. A spiroid tip is a spiral loop formed by joining 

vertical and horizontal winglets. This technique can decrease tip vortex 

intensity and, therefore, reduce lift-induced drag. 

Potential Reductions in 

Modal GHG Emissions 

1.65% 

Potential Reduction in 

Modal Energy Use 

1.65% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information N/A 

Benefits and Drawbacks This practice increases the surface area of the wing of the aircraft, 

which could increase the viscous drag. The effect of additional 

viscous drag associated with the surface area increase is accounted for 

in the estimate given here. 
221

Appendix C.5 Best Practice 3-5: Air Traffic Management Improvement 

This best practice is assessed qualitatively. Table C-5 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table C-5. Simplified Summary Table for Best Practice 3-5, Air Traffic Management 

Improvement 

Attribute Description 

Practice Name Air Traffic Management Improvement 

Mode Type Air 

Subgroup Air Traffic Management 

Responsible Parties 38, 39, 41, 45, 48, 49, 50, 51, 52, 53, 54

Target Parties 14, 15, 16, 17, 18, 19

Target GHGs CO2

Strategy Type Technology/ Operation 

Practice Goals Goal is to have all aircrafts and all airports participate. The reductions 

in modal GHG emissions and energy use in 2025 would be both 6.00%. 

Developmental Status N 

Practice Summary Optimized air traffic management systems are in the development stage. 

Compared to the current air traffic control system, there are 

opportunities to reduce congestion, improve operational efficiency and 

improve aircraft routing in order to reduce fuel consumption. 

Advanced air traffic management systems can optimize air traffic flow, 

provide efficient route, airspace, and departure and landing procedure 

options, and increase situation awareness. 

Potential Reductions in 

Modal GHG Emissions 

6.00% 

Potential Reduction in 

Modal Energy Use 

6.00% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information N/A 

Benefits and Drawbacks N/A 
222

Appendix C.6 Best Practice 3-6: Airframe Weight Reduction 

This best practice is assessed qualitatively. Table C-6 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table C-6. Simplified Summary Table for Best Practice 3-6, Airframe Weight Reduction 

Attribute Description 

Practice Name Airframe Weight Reduction 

Mode Type Air 

Subgroup Weight Reduction 

Responsible Parties 41, 42, 44, 48, 50, 51

Target Parties 16, 17

Target GHGs CO2

Strategy Type Technology 

Practice Goals Goal is to have all aircrafts participate. The reductions in modal GHG 

emissions and energy use in 2025 would be both 2.00%. 

Developmental Status P 

Practice Summary The weight of an airframe is approximately 50% of an aircraft’s gross 

weight. Adoption of advanced lighter and stronger materials in the 

structural components of the airframe, such as aluminum alloy, titanium 

alloy, and composite materials for non-load-bearing structures, can 

reduce airframe weight, thereby leading to a reduction in fuel use. 

Potential Reductions in 

Modal GHG Emissions 

2.00% 

Potential Reduction in 

Modal Energy Use 

2.00% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information N/A 

Benefits and Drawbacks More research and development is needed to reach the projected 

structure weight reduction target. 
223

Appendix C.7 Best Practice 3-7: Non-Essential Weight Reduction 

This best practice is assessed qualitatively. Table C-7 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table C-7. Simplified Summary Table for Best Practice 3-7, Non-Essential Weight Reduction 

Attribute Description 

Practice Name Non-Essential Weight Reduction 

Mode Type Air 

Subgroup Weight Reduction 

Responsible Parties 38, 39, 41, 42, 44, 45, 46

Target Parties 14, 15, 17, 18, 19

Target GHGs CO2

Strategy Type Technology 

Practice Goals Goal is to have all aircrafts participate. The reductions in modal GHG 

emissions and energy use in 2025 would be both 1.00%. 

Developmental Status N 

Practice Summary Trimming non-essential weight from aircraft can reduce fuel use. 

Adjustments to the amount of fuel, water, and emergency equipment 

onboard with respect to anticipated requirements and a contingency 

allowance can reduce fuel use 

Potential Reductions in 

Modal GHG Emissions 

1.00% 

Potential Reduction in 

Modal Energy Use 

1.00% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information N/A 

Benefits and Drawbacks N/A 
224

Appendix C.8 Best Practice 3-8: Ground-Based Equipment as an Alternative to 

Auxiliary Power Units 

This best practice is assessed qualitatively. Table C-8 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table C-8. Simplified Summary Table for Best Practice 3-8, Ground-Based Equipment as an 

Alternative to Auxiliary Power Units 

Attribute Description 

Practice Name Ground-Based Equipment as an Alternative to Auxiliary Power Units 

Mode Type Air 

Subgroup Ground Support Equipment Improvement 

Responsible Parties 38, 39, 41, 42, 44

Target Parties 14, 15, 17, 18

Target GHGs CO2

Strategy Type Technology 

Practice Goals 

Goal is to have all aircrafts and airports participate. The reductions in 

modal GHG emissions and energy use in 2025 for Best Practices 3-8 and 

3-9 would be both 2.94%. 

Developmental Status P 

Practice Summary Aircraft auxiliary power units (APUs) are engine-driven generators that 

supply electricity for use aboard the plane while at a cargo loading area. 

An alternative method for supplying electricity is to connect the aircraft 

to shore-based power or to use ground-based equipment to generate 

power for delivery to the aircraft. Such ground-based equipment has 

been pilot tested. Ground-based equipment can reduce APU fuel use 

significantly while the aircraft is at the gate. 

Potential Reductions in 

Modal GHG Emissions 

2.94%(for Best Practices 3-8 and 3-9) 

Potential Reduction in 

Modal Energy Use 

2.94%(for Best Practices 3-8 and 3-9) 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information N/A 

Benefits and Drawbacks This strategy can only be used when aircrafts are parked at gates. 
225

Appendix C.9 Best Practice 3-9: Electric or Hybrid Heavy Duty Delivery Trucks 

This best practice is assessed qualitatively. Table C-9 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table C-9. Simplified Summary Table for Best Practice 3-9, Electric or Hybrid Heavy Duty 

Delivery Trucks 

Attribute Description 

Practice Name Electric or Hybrid Heavy Duty Delivery Trucks 

Mode Type Air 

Subgroup Ground Support Equipment Improvement 

Responsible Parties 39, 45, 46

Target Parties 15, 16, 17, 18, 19

Target GHGs CO2

Strategy Type Technology 

Practice Goals 

Goal is to have all aircrafts and aircrafts participate. The reductions in 

modal GHG emissions and energy use in 2025 for Best Practices 3-8 and 

3-9 would be both 2.94%. 

Developmental Status P 

Practice Summary Off-road electric or hybrid vehicles for supporting airport operations 

have been pilot-tested. Such vehicles can replace existing, older 

ground support equipment. An off-road electric powered delivery 

vehicle can operate for 100 miles after a single charge, carry 3,000 lbs of 

cargo, travel at a speed of up to 30 miles per hour, and climb grades up 

to 10%. These capabilities are suitable for ground equipment service. 

Other alternative ground support equipment propulsion systems can be 

based on LPG or gasoline powered hybrid vehicles. 

Potential Reductions in 

Modal GHG Emissions 

2.94 % (for Best Practices 3-8 and 3-9) 

Potential Reduction in 

Modal Energy Use 

2.94% (for Best Practices 3-8 and 3-9) 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information N/A 

Benefits and Drawbacks Reduction in cost is needed to expand the market penetration 

potential of this practice. 
226

Appendix C.10 Best Practice 3-10: Improved Engine Overall Efficiency 

This best practice is assessed qualitatively. Table C-10 summarizes the assessment 

results in the standardized simplified reporting table format. 

Table C-10. Simplified Summary Table for Best Practice 3-10, Improved Engine Combustion 

Efficiency 

Attribute Description 

Practice Name Improved Engine Overall Efficiency 

Mode Type Air 

Subgroup Engine Improvement 

Responsible Parties 41, 42, 43, 46, 47

Target Parties 14, 17

Target GHGs CO2

Strategy Type Technology 

Practice Goals Goal is to have all aircrafts participate. The reductions in modal GHG 

emissions and energy use in 2025 would be both 13.00%. 

Developmental Status C 

Practice Summary Current aircraft energy efficiency, the amount of energy used to transport 

one unit of payload over a distance, is about 10-13 MJ per ton-mile. 

Aircraft fuel consumption can be reduced based on improving engine 

efficiency. Engine efficiency can be improved through increasing fan 

bypass ratio, increasing pressure ratio of compressor and better mixing 

of fuel and air prior to combustion. 

A new jet engine with several advanced technologies is being developed 

and is scheduled to enter the market in 2008. This engine features 

larger fan for high engine bypass ratio, a compressor for high pressure 

ratio, and better mixing of fuel and air, which leads to a more 

fuel-efficient engine. 

Potential Reductions in 

Modal GHG Emissions 

13.00% 

Potential Reduction in 

Modal Energy Use 

13.00% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information N/A 

Benefits and Drawbacks N/A 
227

APPENDIX D. DETAILS OF INPUT DATA, ASSUMPTIONS, AND ESTIMATION 

RESULTS FOR WATER MODE BEST PRACTICES

This appendix is additional descriptive information for the best practices in Chapter 7, 

including the standardized reporting tables, if their corresponding best practices can be assessed 

quantitatively, or the simplified summary tables, if their corresponding best practices are 

assessed qualitatively. For those assessed quantitatively, the methods for the estimation of data 

in the standardized reporting tables are also described. 

Appendix D.1 Best Practice 4-1: Off-Center Propeller 

This best practice is assessed qualitatively. Table D 4-1 summarizes the assessment 

results in the standardized simplified reporting table format. 

 

Table D-1. Simplified Summary Table for Best Practice 4-1, Off-Center Propeller 

Attribute Description 

Practice Name Off-Center Propeller 

Mode Type Water 

Subgroup Propeller System Improvement 

Responsible Parties 58, 59

Target Parties 20, 22, 23

Target GHGs CO2

Strategy Type Technology 

Practice Goals Goal is to have half of all ships participate. The reductions in modal 

GHG emissions and energy use in 2025 would be both 1.50%. 

Developmental Status C 

Practice Summary Vortices that are formed along the rear part of the ship and that flow into 

the wake are the result of turbulence. Such vortices are referred to as 

“bilge vortices” and they effectively increase the resistance of water 

movement around the ship hull. An off-center propeller is a 

commercially available device that attempts to capture some of the flow 

and energy contained within the bilge vortices to enhance propulsion 

efficiency. An off-center propeller is part of a system that includes the 

rudder and properly shaft located away from the longitudinal centerline 

of the ship. 

Potential Reductions in 

Modal GHG Emissions 

1.50% 

Potential Reduction in 

Modal Energy Use 

1.50% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information N/A 

Benefits and Drawbacks This practice can be implemented for new ships but is difficult or 

impractical to retrofit to existing ships. 
228

Appendix D.2 Best Practice 4-2: Propeller Boss Cap with Fins 

This best practice is assessed qualitatively. Table D 4-2 summarizes the assessment 

results in the standardized simplified reporting table format. 

 

Table D-2. Simplified Summary Table for Best Practice 4-2, Propeller Boss Cap with Fins 

Attribute Description 

Practice Name Propeller Boss Cap with Fins 

Mode Type Water 

Subgroup Propeller System Improvement 

Responsible Parties 58, 59

Target Parties 20, 22, 23

Target GHGs CO2

Strategy Type Technology 

Practice Goals Goal is to have half of all ships participate. The reductions in modal 

GHG emissions and energy use in 2025 would be both 2.00%. 

Developmental Status C 

Practice Summary Turbulent vortices are generated by propeller rotation. The formation 

of vortices requires energy. Thus, energy that could be used for 

propulsion is diverted to the formation of vortices, which reduces the 

overall energy efficiency of the propulsion system. A method for 

reducing the formation of vortices associated with the propeller ration is 

the use of a propeller boss cap with fins (PBCF). The PBCF includes 

small fins installed behind the propeller and that rotates in the same 

direction as the propeller. The purpose of these fins is to avoid the 

formation of vortices. 

Potential Reductions in 

Modal GHG Emissions 

2.00% 

Potential Reduction in 

Modal Energy Use 

2.00% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information The estimated capital cost of PBCF ranges from $20,000 for 735 kW 

engine to $146,000 for 22,050 kW engine, which can be recovered 

within two years by fuel cost savings 

Benefits and Drawbacks N/A 
229

Appendix D.3 Best Practice 4-3: Auxiliary Free-rotating Propulsion Device behind 

the Main Propellers 

This best practice is assessed qualitatively. Table D 4-3 summarizes the assessment 

results in the standardized simplified reporting table format. 

 

Table D-3. Simplified Summary Table for Best Practice 4-3, Auxiliary Free-Rotating 

Propulsion Device behind the Main Propellers 

Attribute Description 

Practice Name Auxiliary Free-Rotating Propulsion Device behind the Main Propellers 

Mode Type Water 

Subgroup Propeller System Improvement 

Responsible Parties 58, 59

Target Parties 20, 22, 23

Target GHGs CO2

Strategy Type Technology 

Practice Goals Goal is to have half of all ships participate. The reductions in modal 

GHG emissions and energy use in 2025 would be both 3.00%. 

Developmental Status C 

Practice Summary Propeller rotation results in the formation of energy-consuming turbulent 

vortices unless mitigating measures are implemented. An alternative to 

PBCF is a grim vane wheel (GVW). It is an auxiliary free-rotating 

propulsion device that has vanes with larger diameter than that of 

propeller and is located immediately behind the main propeller. The 

rotation of GVW modifies the accelerated flow of water that is leaving 

the propeller, recovers a portion of the energy embodied in the 

accelerated flow of water, and in so doing provides extra propulsion. 

Older designs of GVW are mounted on the propeller shaft, but can have 

problems with mechanical failure. A newly designed GVW system can 

be mounted on the rudder horn instead of propeller shaft, which may 

improve reliability. 

Potential Reductions in 

Modal GHG Emissions 

3.00% 

Potential Reduction in 

Modal Energy Use 

3.00% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information The estimated capital cost of new-designed GVW is approximately 

$1.2 million dollars, which can be recovered in about three years 

based on fuel cost savings. 

Benefits and Drawbacks A newly designed GVW system can be mounted on the rudder horn 

instead of propeller shaft, which may improve reliability. 
230

Appendix D.4 Best Practice 4-4: Shoreside Power for Marine Vessels at Ports 

This best practice is assessed qualitatively. Table D 4-4 summarizes the assessment 

results in the standardized simplified reporting table format. 

 

Table D-4. Simplified Summary Table for Best Practice 4-4, Shoreside Power for Marine 

Vessels at Ports 

Attribute Description 

Practice Name Shoreside Power for Marine Vessels at Ports 

Mode Type Water 

Subgroup Anti-Idling 

Responsible Parties 56, 58, 59

Target Parties 20, 21, 23, 24

Target GHGs CO2

Strategy Type Technology 

Practice Goals Goal is to have 60% of all ships participate. The reductions in modal 

GHG emissions and energy use in 2025 would be 0.16% and -0.04%. 

Developmental Status P 

Practice Summary Shoreside power is being tested as ship anti-idling system that can avoid 

the need for running the ship auxiliary engine continuously while a ship 

is docked at a port. Shoreside power is a system that connects the ship 

to an external electrical power source, thereby avoiding the need for use 

of the auxiliary engine. Thus, this system can reduce ship fuel use and 

GHG emissions. 

Potential Reductions in 

Modal GHG Emissions 

0.16% 

Potential Reduction in 

Modal Energy Use 

-0.04% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information N/A 

Benefits and Drawbacks This practice can reduce GHG emissions and criteria air pollutions at 

ports. It can avoid the need for use of the on-board auxiliary engine. 

However, the fuel use for the auxiliary engine is only a small fraction 

of total marine fuel use. 
231

Appendix D.5 Best Practice 4-5: B20 Biodiesel Fuel for Ships 

This best practice is assessed quantitatively. Table D-5 summarizes the assessment 

results. This table is in the format of the standardized reporting table for quantitative results. 

The basis of the quantitative estimates is explained.

A. Estimate of total number of vehicles or devices: 

(Not available: this value is not estimated in this study). 

B. Estimate of annual transport activity for the mode: 

(a) Assumption: i. It is estimated that total transport activity hauled by domestic 

water mode in the U.S. in 2003 is 606 × 109 ton-miles.141-142 

ii. It is estimated that total transport activity hauled by oceangoing 

ships in the world in 2003 is 25,844 × 109 ton-miles.143 

iii. International marine fuel consumption is estimated to be 284× 

106 metric tons, 71% of international marine fuel consumption is 

used for freight activities, and 70% of marine fuel is residual 

fuel oil and 30% is distillate fuel oil.144 

iv. International marine bunker fuel purchased from the U.S. in 

2003 is estimated to be 321.7× 1012 BTU.1 

v. The ratio of international marine transport activity in the U.S. to 

international marine transport activity in the world is 

proportional to the ratio of energy use for marine transport 

activity in the U.S. and that in the world. 

vi. The growth rate of total transport activity is the same as the 

growth rate of energy use for the water mode. 
232

Table D-5. Standardized Reporting Table for Best Practice 4-5, B20 Biodiesel Fuel for Shipsa

Characteristics of the Practice Description 

Practice Name B20 Biodiesel Fuel for Ships 

Mode Type Water 

Subgroup Alternative Fuel 

Responsible Parties 58, 61

Target Parties 23, 25

Target GHGs CO2

Strategy Type Technology 

Practice Goals 

Goal is to have all ships using distillate 

fuel participate. The reductions in 

modal GHG emissions and energy use in 

2025 would be 1.22% (1.5 ×106

 tons of 

CO2 eq.) and -1.25% (-18 ×1012 Btu), 

respectively. 

Developmental Status N 

Practice Summary The life-cycle CO2 emissions coefficient 

of B20 biodiesel decreases by 0.0069 tons 

CO2 eq. per 106

 BTU compared to that of 

land-use petroleum diesel fuel. 

Land-use diesel fuel and marine gas oil 

belong to distillate fuel except that the 

land-use diesel fuel has a much lower 

sulfur level than the marine gas oil. 

Sulfur concentrations in distillate fuels 

can be reduced by a refining process, 

hydro-treating, that consumes energy and 

emits CO2. Since removal of sulfur 

emits more GHG, the production of 

marine gas oil emits less GHG than the 

production of land-use diesel fuel based 

on life cycle inventories. Thus, the latter 

provides a useful upper bound of the 

former. 

Emissions, Energy Use, and Refrigerant Use Unit Value 

Annual Transport Activity for the Mode (ATAM) 109 ton-miles/year 2,027 

Annual Transport Activity to Which a Practice Is 

Applicable (ATAP) 109

 ton-miles/year 591 

Annual GHG Emissions Reductions(AGR) 106 ton CO2 eq./year 1.5 

Annual Energy Use Reduction (AER) 1012 BTU /year -18 

Annual Refrigerant Use Reduction (ARR) lbs/year N/A 

Unit GHG Emissions Reductions (UGER) 10-3 lb CO2 eq./ton-mile 5 

Unit Energy Use Reduction (UER) BTU /ton-mile -31 

Unit Refrigerant Use Reduction (URR) lbs/ton-mile N/A 

Practice Costs 

Capital Cost (C) 106 USD ($) N/A 

Discount Rate (r) % 10% 

Technical Lifetime of Technology (L) years N/A 

Fixed Charge Factor (a) year-1 N/A 

Annual O & M Cost (AOM) $106 /year N/A 
233

Annualized Cost (AC) $106 /year 178

Annual Energy Cost Saving (AECS) $106 /year 0 

Annual Refrigerant Cost Saving (ARCS) $106 /year N/A 

Net Savings (NS) $106 /year -178 

Net Savings per Unit of GHG Emissions Reductions 

(NSGR) $/ton CO2 eq. -120 

Net Savings per Unit of Energy Use Reduction (NSER) $/106 BTU N/Ab

Net Savings per Unit of Refrigerant Use Reduction 

(NSRR) $/lb N/A 

Simple Payback Period (SPP) years N/Ac

a

 These assessments are based on the assumptions that these best practices reach their potential 

maximum market shares in 2025. 

b

 This practice has no energy use reduction due to an increase in energy use, and it has no net saving 

due to high annualized cost and no energy cost saving. c

 There is no pay-back period for this best practice because there is no net saving. 

(b) Calculation: i. Fuel use for international marine freight transportation in 2003 is 

estimated to be 8.5× 1015 BTU. 

 

( ) 284 10 metric tons 71% 8.5 10 BTU

lb

19,011 BTU 70%

lb

19,600 BTU 30%

metric tons

2,205 lb

6 15 × × = ×





 





















+ × 















× × 















ii. The ratio of international marine transport activity in the U.S. to 

international marine transport activity in the world is estimated 

to be 3.8% 

 3.8%

8.5 10 BTU

321.7 10 BTU

15

12

= ×

×

iii. Total transport activity hauled by oceangoing ships in the U.S. 

in 2003 is estimated to be 982 × 109

 ton-miles.143 

 ( ) 25,844 10 3.8% ton miles 982 10 ton miles 9 9 × × − = × −

(c) 2003 Results: The estimated total transport activity for the water mode in the 

U.S. in 2003 is 1,588 ×109 ton-miles. 
234

( ) 606 10 982 10 ton miles 1,588 10 ton miles 9 9 9 × + × − = × −

(d) 2025 Results: Since total energy use for the water mode is estimated to grow by 

27.7% from 2003 to 2025,4

 the estimated total transport activity for 

the water mode in the U.S. in 2025 will be 2,027 ×109 ton-miles. 

C. Estimate of annual transport activity to which a practice is applicable: 

(a) 

Assumption: i. Distillate fuel use for domestic water trade in the U.S. is estimated to be 

35% of total fuel use for domestic water trade in the U.S. in 2003.3 

ii. Distillate fuel use for oceangoing bunker fuel purchased in the U.S. is 

estimated to be 26% of total fuel use for oceangoing bunker fuel 

purchased in the U.S. in 2003.1

 

iii. The ratio of marine transport activity powered by distillate fuel to 

marine transport activity powered by total marine fuel is proportional 

to the ratio of distillate fuel use for marine transport activity to total 

fuel use for marine transport activity. 

iv. The growth rate of transport activity to which this practice is 

applicable is the same as the growth rate of energy use for the water 

mode. 

(b) Calculation: The estimated total marine transport activity powered by distillate fuel in 

the U.S. in 2003 is 463 ×109

 ton-miles. 

(( ) ( ))

463 10 ton miles

606 10 35% 982 10 26% ton miles

9

9 9

= × −

× × + × × −

(d) Results: Since total energy use for the water mode is estimated to grow by 27.7% 

from 2003 to 2025, 4 the estimated total marine transport activity powered 

by distillate fuel in the U.S. in 2025 will be 591 ×109 ton-miles. 

D. Estimate of annual GHG emissions reductions: 

 (a) Assumption: i. The net life-cycle CO2 emissions reduction of B20 biodiesel is 

about 0.0069 tons CO2 eq. per 106 BTU compared to land-use 
235

diesel fuel , which is estimated in Appendix F.2.3.61 

ii. Biodiesel industry was estimated that it has the potential to 

produce 1.7 billion gallons of B100 biodiesel in 2003, 3.5 billion 

gallons of B100 biodiesel in 2015, and 10 billion gallons of 

B100 biodiesel in 2030.63,64 Thus, the estimated production of 

B100 biodiesel in 2025 is 7.8 billion gallons. 

iii. The estimated heating value of B100 biodiesel is 126,789 

BTU/gallon, and the estimated heating value of petroleum diesel 

is 138,690 BTU/gallon.132-133 Thus, the estimated heating 

value of B20 biodiesel is 136,310 BTU/gallon. 

iv. The truck mode consumed 4.6×1015 BTU of diesel fuel in 

2003.2,3 The rail mode consumed 0.531×1015 BTU diesel in 

2003.3 The water mode consumed 0.385×1015 BTU distillate 

fuel oil in 2003.1,3 

v. The potential market share of B20 biodiesel for the water mode 

is estimated as 25.7% in 2025 based on the potential maximum 

production capacity of biodiesel, which is estimated as 7.8 

billion gallons in 2025, and the distribution ratio among the 

truck, rail and water modes. 

vi. Land-use diesel fuel and marine gas oil are both distillate fuels 

but differ in that land-use diesel fuel has a much lower sulfur 

level than the marine gas oil. Sulfur concentrations in distillate 

fuels can be reduced by a refining process, hydro-treating, that 

consumes energy and emits CO2.

111 

vii. Since marine gas oil is high sulfur diesel fuel and removal of 

sulfur emits more GHG, the production of marine gas oil emits 

less GHG than the production of land-use diesel fuel based on 

life cycle inventories. The difference of life cycle GHG 

emission analysis results between B20 biodiesel and marine gas 

oil should be lower than the difference between B20 biodiesel 

and land-use diesel fuel. Thus, the latter provides a useful 

upper bound of the former. 

viii. Energy use for the water mode in 2025 is estimated to be 
236

1.43×1015 BTU.1,3

ix. For marine fuel consumption, residual fuel oil for freight ships 

is about 60% of total marine fuel use. Distillate fuel for freight 

ships is about 11% of total marine fuel use. Distillate fuel for 

other ships (such as passenger ships, fish ships, military ships) 

accounts for other 29% of marine fuel use.112 Thus, distillate 

fuel for freight ships is estimated to be 15% of total fuel for 

freight ships. 

(b) Calculation: i. Even though maximum B20 biodiesel production capacity for the 

water mode in 2025 may reach 25.7% of total fuel for freight 

ships, but only 15% of total fuel for freight ships are distillate 

fuel. 

ii. Maximum B20 biodiesel for the water mode in 2025 is 

estimated to be 0.215×1015 BTU. 

 1.43 10 BTU 15% 0.215 10 BTU 15 15 × × = ×

iii. The annual GHG emissions reductions are estimated to be 

1.48×106 tons CO2 eq. in 2025. 

 1.48 10 tons CO eq. 10 BTU

0.0069 CO eq. 0.215 10 BTU 2

6

6

15 2 × × = ×

(c) Results: The annual GHG emissions reductions are estimated to be 

1.48×106 tons CO2 eq. in 2025. 

E. Estimate of annual energy use reduction: 

i. Energy use reduction based on life cycle inventory is estimated to be -8.3%, which is 

estimated in Appendix A.33.E. 

ii. Energy use reduction based on life cycle inventory is estimated to be -1.8×1013 BTU 

 8.3%. 0.215 10 BTU 1.8 10 BTU 15 13 − × × = − ×

F. Estimate of unit GHG emissions reductions: 
237

ton mile

0.0050 lb CO eq.

ton

2,000 lbs . 591 10 ton miles

1.48 10 tons CO eq 2

9

2

6

− =















×















× −

×

G. Estimate of unit energy use reduction: 

( )

ton mile

30.5 BTU . 591 10 ton miles1.8 10 10 BTU 9

7 6

−

− = 















× −

− ×

H. Estimate of capital cost 

(Not available) 

I. Estimate of annual O & M cost

(Not available) 

J. Estimate of annualized cost: 

i. The average fuel cost of B100 Biodiesel in April 2005 is estimated to be $22.2 per 106

BTU.137 

ii. High sulfur diesel fuel price in 2025 is the same as the price of the second season of 

2005, which is $18.03/106 BTU.115 

iii. Thus, B20 biodiesel fuel price is estimated to be $18.86/106 BTU, which is $0.83/106

BTU higher than the price of high sulfur diesel fuel. 

iv. Annualized cost is estimated to be $178 ×106

. 

15 6

6 0.215 10 BTU $178 10

10 BTU

$0.83

× × = ×

K. Estimate of energy cost reduction: 

 (No energy cost reduction) 

L. Estimate of net savings: 

6 6 $0 − $178×10 = −$178×10
238

M. Estimate of net savings per unit of GHG emissions reductions: 

ton CO eq.

$120.4

1.48 10 tons CO eq.

$178 10

2 2

6

6 − = ×

− ×

N. Estimate of net savings per unit of energy use reduction: 

 (Not available: This practice has no energy use reduction due to an increase in energy 

use, and it has no net saving due to high annualized cost and no energy cost saving). 

O. Estimate of simple payback period: 

 (Not available: there is no pay-back period for this practice because there is no net 

saving). 
239

APPENDIX E. DETAILS OF INPUT DATA, ASSUMPTIONS, AND ESTIMATION 

RESULTS FOR PIPELINE MODE BEST PRACTICES 

This appendix is additional descriptive information for the best practices in Chapter 8, 

including the standardized reporting tables, if their corresponding best practices can be assessed 

quantitatively, or the simplified summary tables, if their corresponding best practices are 

assessed qualitatively. For those assessed quantitatively, the methods for the estimation of data 

in the standardized reporting tables are also described. 

Appendix E.1 Best Practice 5-1: Convert Natural Gas Pneumatic Controls to 

Instrument Air 

This best practice is assessed quantitatively. Table E-1 summarizes the assessment 

results. This table is in the format of the standardized reporting table for quantitative results. 

The basis of the quantitative estimates is explained.

A. Estimate of total number of vehicles or devices: 

(a) Assumption: The growth rate of pneumatic control devices is the same as the 

growth rate of total GHG emissions for the pipeline mode. 

(b) 2003 Results: It is estimated that there were 110,000 pneumatic control devices 

in the pipeline mode in 2003.117 

(c) 2025 Results: Since total GHG emissions for the pipeline mode is estimated to 

grow by 14.6% from 2003 to 2025, which is explained in Section 

1.2, there will be 126,100 pneumatic control devices in 2025. 

B. Estimate of annual transport activity for the mode: 

(a) Assumption: The growth rate of total transport activity is the same as the growth 

rate of total GHG emissions for the pipeline mode. 

(b) 2003 Results: It is estimated that there were 335×109

 ton-miles in 2003.3 

(c) 2025 Results: Since total GHG emissions the pipeline mode is estimated to grow 

by 14.6% from 2003 to 2025, which is explained in Section 1.2, 

there will be 384 ×109

 ton-miles in 2025. 
240

Table E-1. Standardized Reporting Table for Best Practice 5-1, Convert Natural Gas Pneumatic 

Controls to Instrument Aira

Characteristics of the Practice Description 

Practice Name Convert Natural Gas Pneumatic Controls 

to Instrument Air 

Mode Type Pipeline 

Subgroup Process Control Device Improvement 

Responsible Parties 70, 71, 72, 73

Target Parties 26, 27, 28

Target GHGs CH4

Strategy Type Technology 

Practice Goals 

Goal is to have 10% of natural 

gas-powered pneumatic control systems 

participate. The reductions in modal 

GHG emissions and energy use in 2025 

would be 0.50% (0.65 ×106

 tons of CO2 

eq.) and 0.13% (1.20 ×1012 Btu), 

respectively. 

Developmental Status C 

Practice Summary Pneumatic control systems for pipelines 

are currently operated using pressurized 

natural gas. However, pneumatic 

controls based on compressed air could be 

used instead. Since natural gas is 

continuously bled from the current control 

devices, they are one of the largest 

methane emissions sources in the natural 

gas industry. Conversion of pneumatic 

control systems from natural gas to 

compressed air would reduce methane 

emissions 

Emissions, Energy Use, and Refrigerant Use Unit Value 

Annual Transport Activity for the Mode (ATAM) 109 ton-miles/year 384 

Annual Transport Activity to Which a Practice Is 

Applicable (ATAP) 109

 ton-miles/year 384 

Annual GHG Emissions Reductions(AGR) 106 ton CO2 eq./year 0.65 

Annual Energy Use Reduction (AER) 1012 BTU /year 1.20 

Annual Refrigerant Use Reduction (ARR) lbs/year N/A 

Unit GHG Emissions Reductions (UGER) 10-3 lb CO2 eq./ton-mile 3.4 

Unit Energy Use Reduction (UER) BTU /ton-mile 3.1 

Unit Refrigerant Use Reduction (URR) lbs/ton-mile N/A 

Practice Costs 

Capital Cost (C) 106 USD ($) 3.7 

Discount Rate (r) % 10% 

Technical Lifetime of Technology (L) years 15 

Fixed Charge Factor (a) year-1 0.131 

Annual O & M Cost (AOM) $106 /year 1.2 

Annualized Cost (AC) $106 /year 1.7

Annual Energy Cost Saving (AECS) $106 /year 13.2 
241

Annual Refrigerant Cost Saving (ARCS) $106 /year N/A 

Net Savings (NS) $106 /year 11.5 

Net Savings per Unit of GHG Emissions Reductions 

(NSGR) $/ton CO2 eq. 17.6 

Net Savings per Unit of Energy Use Reduction (NSER) $/106 BTU 9.6 

Net Savings per Unit of Refrigerant Use Reduction 

(NSRR) $/lb N/A 

Simple Payback Period (SPP) years 0.31 a

 These assessments are based on the assumptions that these best practices reach their potential 

maximum market shares in 2025. 

C. Estimate of annual transport activity to which a practice is applicable: 

Annual transport activity to which this practice is applicable is the same as the total 

ton-miles of this mode, which is explained in Appendix E.1.B. 

D. Estimate of annual GHG emissions reductions: 

 (a) Assumption: i. Total GHG emissions reductions are due to methane emission 

reduction. 

ii. The natural gas pipeline mode emits 38.3 ×106

 tons CO2 by 

using energy and emits 74.9 ×106 tons CO2 eq. of methane in 

2003 because of the leakage of natural gas.1 Thus, the pipeline 

mode emits 113.2×106 tons CO2 eq. of GHG in 2003. Since 

the pipeline mode is estimated to grow by 15% from 2003 to 

2025, there will be 129.6 ×106 tons CO2 eq. of GHG for the 

pipeline mode in 2025. 

iii. Pneumatic control devices in the natural gas industry is 

estimated to emit 949 Gg of methane in 2003.1

 

iv. The pipeline mode in the natural gas industry is its transmission 

sector, which emit 26% of methane.117 

v. Approximately 10% of pneumatic control systems powered by 

natural gas are assumed to be replaced by pneumatic control 

systems powered by compressed instrument air. Thus, 12,610 

of pneumatic control devices are estimated to be replaced in 

2025. 
242

vi. Since pneumatic control systems powered by compressed 

instrument air consume electricity,12,610 of pneumatic control 

devices are estimated to consume 11×106 kWh of electricity.117 

vii. The estimated emission factor for electricity is 0.0007 tons CO2

eq. per kWh.108 

(b) Calculation: i. Pneumatic control devices for the pipeline mode are estimated to 

emit 5.71×106 tons CO2 eq. of GHG in 2003. 

 

5.71 10 Tons CO eq.

2,000 lb

Ton

453.6 g

lb

Gg

10 g

CH

21 CO eq. 949 Gg CH 26%

2

6

9

4

2

4

= ×













× × × × ×

ii. Since the pipeline mode is estimated to grow by 15% from 2003 

to 2025, there will be 6.55 ×106 tons CO2 eq. of GHG emitted 

from the pneumatic control devices in 2025. 

 5.71 10 Tons CO eq. 15% 6.55 10 Tons CO eq. 2

6

2

6 × × = ×

iii. Total methane emissions reductions in 2025 due to the 

replacement of 10% of pneumatic control devices are estimated 

to be 0.655×106 tons CO2 eq. 

6.55 10 tons CO eq. 10% 0.655 10 tons CO eq. 2

6

2

6 × × = ×

iv. Total GHG emissions due to using electricity to power 12,610 

of pneumatic control devices are estimated to be 0.008 ×106

 tons 

CO2 eq. 

v. Thus, total GHG emissions reductions are estimated to be 

0.65×106 tons CO2 eq. in 2025. 

6.5 10 Tons CO eq.

0.655 10 Tons CO eq. 0.008 10 Tons CO eq.

2

6

2

6

2

6

= ×

× − ×

(c) Results: The annual GHG emissions reductions are estimated to be 
243

0.65×106 tons CO2 eq. in 2025. 

E. Estimate of annual energy use reduction: 

(a) Assumption: i. Total energy use reduction is that natural gas emission reduction 

minuses energy for producing electricity for operating this practice. 

ii. 1 lb of natural gas contains 21,300 BTU of energy, which is 

explained in Appendix F.1.6. 

iii. 1 kWh is equal to 3,412 BTU. 

iv. The ratio of primary energy input to electricity output is estimated 

to be 2.89 based on total electricity generated and total primary 

energy consumed in the U.S. in 2005.133

(b) Calculation: i. Natural gas emission reduction in 2025 for adopting this practice is 

estimated to be 1.33×1012 BTU. 

1.33 10 BTU.

115%

lb

21,300 BTU

453.6 g

lb

Gg

10 g 949 Gg CH 26% 10%

12

9

4

= ×

×

















× × × × ×

ii. Primary energy needed for producing electricity in order to operate 

this practice in 2025 is estimated to be 0.11×1012 BTU. 

 2.89 0.11 10 BTU

kWh

3412 BTU

11 10 kWh 6 12 × × × = × 

iii. The estimated annual energy use reduction in 2025 is 1.2×106 (106

BTU). 

 1.33 10 BTU 0.11 10 BTU 1.2 10 (10 BTU) 12 12 6 6 × − × = ×

(c) Results: The estimated annual energy use reduction in 2025 is 1.2 ×106

 (106

BTU). 

F. Estimate of unit GHG emissions reductions: 
244

ton mile

0.0034 lb CO eq.

ton

2,000 lbs . 384 10 ton miles

0.65 10 tons CO eq 2

9

2

6

− =















×















× −

×

G. Estimate of unit energy use reduction: 

( )

ton mile

3.1 BTU . 384 10 ton miles1.2 10 10 BTU

9

6 6

− = 















× −

×

H. Estimate of capital cost 

i. The capital cost for this practice for a facility is estimated to be $50,000, and this 

practice in this facility reduces natural gas emissions by 0.02 billion cubic feet (BcF).117 

ii. Natural gas emission reduction from adopting this practice for the pipeline mode is 

estimated to be 1.5 BcF in 2025. 

 

1.5 BcF.

115%

lb

0.04246 lbs

453.6 g

lb

Gg

10 g 949 Gg CH 26% 10%

9

4

=

×

















× × × × ×

iii. Total capital costs for adopting this practice in 2025 are estimated to be $3.7 ×106. 

 6 $3.7 10

0.02 BcF

1.5 BcF

$50,000 × = ×

I. Estimate of annual O & M cost

i. The annual O & M cost for this practice for a facility is estimated to be $3,200, and this 

practice in this facility reduces natural gas emissions by 0.02 billion cubic feet (BcF).117 

ii. The annual electricity cost for this practice for a facility is estimated to be $13,140, and 

this practice in this facility reduces natural gas emissions by 0.02 billion cubic feet 

(BcF).117 

iii. Natural gas emission reduction from adopting this practice for the pipeline mode is 

estimated to be 1.5 BcF in 2025, which is estimated in Appendix F.1.H. 

iv. The annual O & M costs, which include the electricity cost, for adopting this practice 
245

in 2025 are estimated to be $1.2 ×106. 

 ( ) 6 $1.2 10

0.02 BcF

1.5 BcF

$13,140 + $3,200 × = ×

J. Estimate of annualized cost: 

i. The life-time of this practice is estimated to be 15 years. 

ii. Fixed charge factor is estimated to be 0.131. 

( )

( )

0.131

1 0.1

1

1 Fixed ch arg e factor a

15

i 1 i

=

































+

=

∑=

iii. Annualized cost is estimated to be $1.7 ×106

 in 2025. 

( ) 6 6 6 $3.7 ×10 × 0.131 + $$1.2×10 = $1.7×10

K. Estimate of energy cost reduction: 

(a) Assumption: i. Natural gas price in 2025 is the same as the price of September 

2005, which is $10.26 per thousand cubic feet. 114 

ii. Heating value of natural gas is estimated to be 1,031 BTU per 

cubic feet.145

ii. Thus, natural gas price in 2025 is estimated to be $9.95/106

BTU. 

(b) Calculation: i. Natural gas reduction is estimated to be 1.33×1012 BTU, which is 

estimated in Appendix E.1.E. 

ii. The estimated energy cost reduction in 2025 is $13.2 ×106

. 

( ) 6

6

6 6 $13.2 10

10 BTU

$9.95 1.33×10 10 BTU × = ×

(c) Results: The estimated energy cost reduction in 2025 is $13.2 ×106

. 

L. Estimate of net savings: 

6 6 6 $13.2×10 − $1.7×10 = $11.5×10
246

M. Estimate of net savings per unit of GHG emissions reductions: 

ton CO eq.

$17.6

0.65 10 tons CO eq.

$11.5 10

2 2

6

6

= ×

×

N. Estimate of net savings per unit of energy use reduction: 

10 BTU

$9.6

1.2 10 BTU

$11.5 10

12 6

6

= ×

×

O. Estimate of simple payback period: 

( ) 0.31 years $13.2 10 $1.2 10

$3.7 10

6 6

6

= × − ×

×
247

Appendix E.2 Best Practice 5-2: Replace High-Bleed Natural Gas Pneumatic Devices 

with Low-Bleed Pneumatic Devices 

This best practice is assessed quantitatively. Table E-2 summarizes the assessment 

results. This table is in the format of the standardized reporting table for quantitative results. 

The basis of the quantitative estimates is explained.

A. Estimate of total number of vehicles or devices: 

(a) Assumption: Annual per-device GHG emissions in 2025 are the same as annual 

per-device GHG emissions in 2003 for the pipeline mode. 

(b) 2003 Results: i. It is estimated that there were 110,000 pneumatic control 

devices in the pipeline mode in 2003.117 

ii. Approximately 26% of pneumatic control devices are high-bleed 

devices. 

iii. Thus, it is estimated that there were 28,600 high-bleed 

pneumatic control devices in the pipeline mode in 2003. 

(c) 2025 Results: Since total GHG emissions for the pipeline mode is estimated to 

grow by 14.6% from 2003 to 2025, which is explained in Section 

1.2, there will be 32,800 high-bleed pneumatic control devices in 

2025. 

B. Estimate of annual transport activity for the mode: 

Annual transport activity for this mode is explained in Appendix E.1.B. 

C. Estimate of annual transport activity to which a practice is applicable: 

Annual transport activity to which this practice is applicable is the same as the total 

ton-miles of this mode, which is explained in Appendix E.1.B. 
248

Table E-2. Standardized Reporting Table for Best Practice 5-2, Replace High-Bleed Natural 

Gas Pneumatic Devices with Low-Bleed Pneumatic Devicesa

Characteristics of the Practice Description 

Practice Name 

Replace High-Bleed Natural Gas 

Pneumatic Devices with Low-Bleed 

Pneumatic Devices 

Mode Type Pipeline 

Subgroup Process Control Device Improvement 

Responsible Parties 70, 71, 72, 73

Target Parties 26, 27, 28

Target GHGs CH4

Strategy Type Technology 

Practice Goals 

Goal is to have 26% of natural 

gas-powered pneumatic control systems 

participate. The reductions in modal 

GHG emissions in 2025 would be 0.57% 

(0.75 ×106

 tons of CO2 eq.) and 0.16% 

(1.5 ×1012 Btu), respectively. 

Developmental Status C 

Practice Summary High-bleed pneumatic control systems are 

based on high-bleed compressed methane. 

An alternative designed is based on 

low-bleed compressed methane that 

reduces methane emission. 

Emissions, Energy Use, and Refrigerant Use Unit Value 

Annual Transport Activity for the Mode (ATAM) 109 ton-miles/year 384 

Annual Transport Activity to Which a Practice Is 

Applicable (ATAP) 109

 ton-miles/year 384 

Annual GHG Emissions Reductions(AGR) 106 ton CO2 eq./year 0.75 

Annual Energy Use Reduction (AER) 1012 BTU /year 1.5 

Annual Refrigerant Use Reduction (ARR) lbs/year N/A 

Unit GHG Emissions Reductions (UGER) 10-3 lb CO2 eq./ton-mile 3.9 

Unit Energy Use Reduction (UER) BTU /ton-mile 3.9 

Unit Refrigerant Use Reduction (URR) lbs/ton-mile N/A 

Practice Costs 

Capital Cost (C) 106 USD ($) 13.6 

Discount Rate (r) % 10% 

Technical Lifetime of Technology (L) years 15 

Fixed Charge Factor (a) year-1 0.131 

Annual O & M Cost (AOM) $106 /year N/A 

Annualized Cost (AC) $106 /year 1.8

Annual Energy Cost Saving (AECS) $106 /year 15.0 

Annual Refrigerant Cost Saving (ARCS) $106 /year N/A 

Net Savings (NS) $106 /year 13.2 

Net Savings per Unit of GHG Emissions Reductions 

(NSGR) $/ton CO2 eq. 17.8 

Net Savings per Unit of Energy Use Reduction (NSER) $/106 BTU 8.8 

Net Savings per Unit of Refrigerant Use Reduction 

(NSRR) $/lb N/A 
249

Simple Payback Period (SPP) years 0.91 a

 These assessments are based on the assumptions that these best practices reach their potential 

maximum market shares in 2025. 

D. Estimate of annual GHG emissions reductions: 

(a) Assumption: i. Total GHG emissions reductions are due to methane emission 

reduction. 

ii. Approximately 86% of high-bleed pneumatic control devices are 

level controllers, and a level controller is estimated to averagely 

emit 66.6×103

 cubic feet of methane per year.118 

iii. Approximately 14% of high-bleed pneumatic control devices are 

pressure controllers, and a pressure controller is estimated to 

averagely emit 91.2×103

 cubic feet of methane per year.118 

iv. The replacement of high-bleed pneumatic control devices by 

low-bleed pneumatic control devices reduce methane emissions by 

90%.119 

v. Approximately 80% of high-bleed pneumatic control systems can 

be replaced by low-bleed pneumatic control systems.118 

(b) Calculation: i. Total methane emission reduction is estimated to be 1.67 BcF in 

2003. 

[( ) ( )] ( )

1.67 BcF

66.6 10 ft 86% 91.2 10 ft 14% 90% 32,800 80% 3 3 3 3

=

× × + × × × × ×

ii. Total methane emission reduction is estimated to be 0.745×106

tons CO2 eq. in 2003. 

 

0.745 10 Tons CO eq.

2,000 lb

Ton

CH

21 CO eq.

ft

0.04246 lbs

1.67 BcF

2

6

4

2

3

= ×

















× × ×

(c) Results: The annual GHG emissions reductions are estimated to be 0.745×106

tons CO2 eq. in 2025. 
250

E. Estimate of annual energy use reduction: 

The estimated annual energy use reduction in 2025 is 1.5 ×1012 BTU. 

1.5 10 BTU

lb

21,300 BTU

ft

0.04246 lbs

1.67 BcF 12

3 = × 















× ×

F. Estimate of unit GHG emissions reductions: 

ton mile

0.0039 lb CO eq.

ton

2,000 lbs . 384 10 ton miles

0.745 10 tons CO eq 2

9

2

6

− =















×















× −

×

G. Estimate of unit energy use reduction: 

( )

ton mile

3.9 BTU . 384 10 ton miles1.5 10 10 BTU

9

6 6

− = 















× −

×

H. Estimate of capital cost 

i. The capital cost for a level controller is estimated to be $380, and the capital cost for a 

pressure controller is estimated to be $1,340.118 

ii. Total capital costs for adopting this practice in 2025 are estimated to be $13.6 ×106. 

 [ ] ( )( ) ( ) 6 $380×86% + $1,340×14% × 32,800×80% = $13.6×10

I. Estimate of annual O & M cost

The O & M cost of a low-bleed device is estimated to be the same as the O & M cost of a 

high-bleed device. Thus, the change of the O & M cost for this practice is zero. 

J. Estimate of annualized cost: 

i. The life-time of this practice is estimated to be 15 years. 

ii. Fixed charge factor is estimated to be 0.131. 
251

( )

( )

0.131

1 0.1

1

1 Fixed ch arg e factor a

15

i 1 i

=

































+

=

∑=

iii. Annualized cost is estimated to be $1.78 ×106

 in 2025. 

( ) 6 6 $13.6×10 × 0.131 = $1.78×10

K. Estimate of energy cost reduction: 

(a) Assumption: Natural gas price in 2025 is estimated to be $9.95/106

 BTU, which 

is estimated in Appendix E.1.K. 

(b) Calculation: i. Natural gas reduction is estimated to be 1.5×1012 BTU, which is 

estimated in Appendix E.2.E. 

ii. The estimated energy cost reduction in 2025 is $15.0 ×106

. 

( ) 6

6

6 6 $15.0 10

10 BTU

$9.95 1.5×10 10 BTU × = ×

(c) Results: The estimated energy cost reduction in 2025 is $15.0 ×106. 

L. Estimate of net savings: 

6 6 6 $15.0×10 − $1.78×10 = $13.24×10

M. Estimate of net savings per unit of GHG emissions reductions: 

ton CO eq.

$17.8

0.745 10 tons CO eq.

$13.24 10

2 2

6

6

= ×

×

N. Estimate of net savings per unit of energy use reduction: 

10 BTU

$8.8

1.5 10 BTU

$13.24 10

12 6

6

= ×

×

O. Estimate of simple payback period: 

( ) 0.91 years $15.0 10

$13.6 10

6

6

= ×

×
252

Appendix E.3 Best Practice 5-3: “Hot Tap” Method 

This best practice is assessed quantitatively. Table E-3 summarizes the assessment 

results. This table is in the format of the standardized reporting table for quantitative results. 

The basis of the quantitative estimates is explained.

A. Estimate of total number of vehicles or devices: 

(a) Assumption: The growth rate of total pipeline length is the same as the growth 

rate of total GHG emissions for the pipeline mode. 

(b) 2003 Results: It is estimated that there were 285,165 miles of pipelines for the 

pipeline mode in 2003.1

 

(c) 2025 Results: Since total GHG emissions for the pipeline mode is estimated to 

grow by 14.6% from 2003 to 2025, which is explained in Section 

1.2, there will be 326,900 miles of pipelines in 2025. 

B. Estimate of annual transport activity for the mode: 

Annual transport activity for this mode is explained in Appendix E.1.B. 

C. Estimate of annual transport activity to which a practice is applicable: 

Annual transport activity to which this practice is applicable is the same as the total 

ton-miles of this mode, which is explained in Appendix E.1.B. 

D. Estimate of annual GHG emissions reductions: 

 (a) Assumption: i. Total GHG emissions reductions are due to methane emission 

reduction. 

ii. A Canadian natural gas company, which own 23,000 miles of 

pipelines, adopted this practice and reduce methane by 8.4×103

tons per year.121 
253

Table E-3. Standardized Reporting Table for Best Practice 5-3, “Hot Tap” Method a

Characteristics of the Practice Description 

Practice Name “Hot Tap” Method 

Mode Type Pipeline 

Subgroup Connecting Method 

Responsible Parties 70, 71, 72, 73

Target Parties 26, 27, 28, 29

Target GHGs CH4

Strategy Type Technology 

Practice Goals 

Goal is to have all pipeline systems 

participate. The reductions in modal 

GHG emissions in 2025 would be 1.93% 

(2.5 ×106

 tons of CO2 eq.) and 0.54% (5.1 

×1012 Btu), respectively. 

Developmental Status C 

Practice Summary Methods for constructing new pipeline 

connections for an existing, operational 

pipeline usually result in significant 

venting of natural gas. In contrast, the 

“hot tap” pipeline connecting method is a 

commercially available technology that 

reduces GHG emissions. This method 

avoids the need for venting natural gas. 

It involves attaching a branch pipeline 

connection on the outside of an operating 

pipeline and cutting out the inside 

pipeline wall. 

Emissions, Energy Use, and Refrigerant Use Unit Value 

Annual Transport Activity for the Mode (ATAM) 109 ton-miles/year 384 

Annual Transport Activity to Which a Practice Is 

Applicable (ATAP) 109

 ton-miles/year 384 

Annual GHG Emissions Reductions(AGR) 106 ton CO2 eq./year 2.5 

Annual Energy Use Reduction (AER) 1012 BTU /year 5.1 

Annual Refrigerant Use Reduction (ARR) lbs/year N/A 

Unit GHG Emissions Reductions (UGER) 10-3 lb CO2 eq./ton-mile 13 

Unit Energy Use Reduction (UER) BTU /ton-mile 13 

Unit Refrigerant Use Reduction (URR) lbs/ton-mile N/A 

Practice Costs 

Capital Cost (C) 106 USD ($) 8.3 

Discount Rate (r) % 10% 

Technical Lifetime of Technology (L) years 15 

Fixed Charge Factor (a) year-1 0.131 

Annual O & M Cost (AOM) $106 /year 9.9 

Annualized Cost (AC) $106 /year 11.0

Annual Energy Cost Saving (AECS) $106 /year 50.6 

Annual Refrigerant Cost Saving (ARCS) $106 /year N/A 

Net Savings (NS) $106 /year 39.6 

Net Savings per Unit of GHG Emissions Reductions 

(NSGR) $/ton CO2 eq. 15.8 
254

Net Savings per Unit of Energy Use Reduction (NSER) $/106 BTU 7.8 

Net Savings per Unit of Refrigerant Use Reduction 

(NSRR) $/lb N/A 

Simple Payback Period (SPP) years 0.2 a

 These assessments are based on the assumptions that these best practices reach their potential 

maximum market shares in 2025. 

(b) Calculation: Total methane emission reduction is estimated to be 2.5×106

 tons 

CO2 eq. in 2025. 

 

2.5 10 Tons CO eq.

23,000 miles

326,900 miles

CH

21 CO eq. 8.4 10 tons CH

2

6

4

2

4

3

= ×

















× × ×

(c) Results: The annual GHG emissions reductions are estimated to be 2.5×106

tons CO2 eq. in 2025. 

E. Estimate of annual energy use reduction: 

The estimated annual energy use reduction in 2025 is 5.1 ×1012 BTU. 

5.1 10 BTU

23,000 miles

326,900 miles

lb

21,300 BTU

ton

2,000 lbs

8.4 10 tons CH 12

4

3 × = × 















× × ×

F. Estimate of unit GHG emissions reductions: 

ton mile

0.013 lb CO eq.

ton

2,000 lbs . 384 10 ton miles

2.5 10 tons CO eq 2

9

2

6

− =















×















× −

×

G. Estimate of unit energy use reduction: 

( )

ton mile

13.2 BTU . 384 10 ton miles5.1 10 10 BTU

9

6 6

− = 















× −

×
255

H. Estimate of capital cost 

i. The capital cost for this practice for a company is estimated to be $36,200, and this 

practice reduces methane emissions by 0.0244 BcF for this company.122 

ii. Methane emission reduction from adopting this practice for the pipeline mode is 

estimated to be 5.61 BcF in 2025. 

 5.61 BcF

23,000 miles

326,900 miles

0.04246 lbs

ft

ton

2,000 lbs

8.4 10 tons CH

3

4

3 × = 















× × ×

iii. Total capital costs for adopting this practice in 2025 are estimated to be $8.32 ×106

. 

 6 $8.32 10

0.0244 BcF

5.61 BcF

$36,200 × = ×

I. Estimate of annual O & M cost

i. The annual O & M cost for this practice for a company is estimated to be $43,000, and 

this practice reduces methane emissions by 0.0244 BcF for this company.122 

ii. The annual O & M costs for adopting this practice in 2025 are estimated to be $9.89 

×106. 

 ( ) 6 $9.89 10

0.0244 BcF

5.61 BcF

$43,000 × = ×

 

J. Estimate of annualized cost: 

i. The life-time of this practice is estimated to be 15 years. 

ii. Fixed charge factor is estimated to be 0.131. 

( )

( )

0.131

1 0.1

1

1 Fixed ch arg e factor a

15

i 1 i

=

































+

=

∑=

iii. Annualized cost is estimated to be $11.0 ×106

 in 2025. 

( ) 6 6 6 $8.32×10 × 0.131 + $9.89×10 = $11.0×10
256

K. Estimate of energy cost reduction: 

(a) Assumption: Natural gas price in 2025 is estimated to be $9.95/106 BTU, which 

is estimated in Appendix E.1.K. 

(b) Calculation: i. Natural gas reduction is estimated to be 5.1×1012 BTU, which is 

estimated in Appendix E.3.E. 

ii. The estimated energy cost reduction in 2025 is $50.6 ×106. 

( ) 6

6

6 6 $50.6 10

10 BTU

$9.95 5.1×10 10 BTU × = ×

(c) Results: The estimated energy cost reduction in 2025 is $50.6 ×106

. 

L. Estimate of net savings: 

6 6 6 $50.6×10 − $11.0×10 = $39.6×10

M. Estimate of net savings per unit of GHG emissions reductions: 

ton CO eq.

$15.8

2.5 10 tons CO eq.

$39.6 10

2 2

6

6

= ×

×

N. Estimate of net savings per unit of energy use reduction: 

10 BTU

$7.8

5.1 10 BTU

$39.6 10

12 6

6

= ×

×

O. Estimate of simple payback period: 

( ) 0.20 years $50.6 10 $9.89 10

$8.32 10

6 6

6

= × − ×

×
257

Appendix E.4 Best Practice 5-4: Transfer Compression 

This best practice is assessed qualitatively. Table E-4 summarizes the assessment results 

in the standardized simplified reporting table format. 

 

Table E-4. Simplified Summary Table for Best Practice 5-4, Transfer Compression 

Attribute Description 

Practice Name Transfer Compression 

Mode Type Pipeline 

Subgroup Maintenance 

Responsible Parties 70, 71, 72

Target Parties 26, 27, 28

Target GHGs CH4

Strategy Type Technology 

Practice Goals 

Goal is to have all pipeline systems participate. The reductions in 

modal GHG emissions and energy use in 2025 would be 0.07% and 

0.02%, respectively. 

Developmental Status C 

Practice Summary During the pipeline maintenance process, a section of pipe is often 

isolated and taken out for maintenance, and methane is vented from the 

isolated section. An alternative to venting is to transfer the natural gas 

in the isolated section to an operating section of the pipeline, thereby 

avoiding loss of methane. A system for doing this is a transfer 

compressor unit, which is commercially available. Several transfer 

compressors can be operated simultaneously to increase the methane 

recovery rate. 

Potential Reductions in 

Modal GHG Emissions 

0.07% 

Potential Reduction in 

Modal Energy Use 

0.02% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information N/A 

Benefits and Drawbacks N/A 
258

Appendix E.5 Best Practice 5-5: Inline Inspection 

This best practice is assessed qualitatively. Table E-5 summarizes the assessment results 

in the standardized simplified reporting table format. 

 

Table E-5. Simplified Summary Table for Best Practice 5-5, Inline Inspection 

Attribute Description 

Practice Name Inline Inspection 

Mode Type Pipeline 

Subgroup Maintenance 

Responsible Parties 70, 71, 72, 73

Target Parties 26, 27, 28

Target GHGs CH4

Strategy Type Technology 

Practice Goals 

Goal is to have all pipeline systems participate. The reductions in 

modal GHG emissions and energy use in 2025 would be 1.32% and 

0.37%, respectively. 

Developmental Status C 

Practice Summary Pipeline flaws, especially stress corrosion cracking (SCC), cause 

pipeline failure that are of safety concern and that lead to fugitive 

methane emissions. A pipeline inline inspection (ILI) tool, referred to 

as “smart pig,” was originally designed to inspect internal pipeline 

conditions, such as dents or metal loss, by using ultrasound. A 

ultrasound inline inspection tool based on a newer design can detect not 

only dents or metal loss, but also SCC. This new tool is able to locate 

more pipeline flaws. By identifying and correcting such flaws sooner, 

fugitive methane emissions can be reduced. 

Potential Reductions in 

Modal GHG Emissions 

1.32% 

Potential Reduction in 

Modal Energy Use 

0.37% 

Potential Reduction in 

Modal HFC Use 

N/A 

Cost Information N/A 

Benefits and Drawbacks This upgraded tool can find more flaws in the pipeline system and, 

therefore, enable quickly corrective action lead to larger reductions in 

fugitive methane emissions. 
259

APPENDIX F. FUEL PROPERTIES, CO2 EMISSIONS COEFFICIENTS FOR FULES, 

AND AVERAGE UNIT FUEL COSTS FOR GUIDEBOOK 

APPENDIX F.1 Properties of Different Fuels 

Many of the GHG emissions from freight transportation sector are related to fuel use, and 

are influenced by the types of fuels and the properties of fuels. Major fuels used in the freight 

transportation sector include diesel fuel, jet fuel, residual fuel oil, biodiesel, and natural gas. 

For these fuels, there are usually a number of parameters that are used to measure chemical and 

physical properties. These fuel properties impact the performance of vehicle operation and 

influence the fuel usage and the GHG emissions from freight transportation. For example, the 

energy density of the fuel will have an affect on the apparent fuel economy.131 This section 

describes the important parameters for measuring fuel properties, and discusses the fuel 

properties of diesel fuel, jet fuel, residual fuel oil, biodiesel, and natural gas. 

F.1.1 Definitions of Fuel Properties 

The following subsections describe several fuel properties, including specific gravity, 

cetane number, distillation range, aromatic content, heating value, and viscosity, which influence 

the performance of vehicle operation and would impact greenhouse gas emissions from the 

freight transportation. 

F.1.1.1 Specific Gravity 

The specific gravity is defined as the ratio of the density of the fuel to the density of 

water at 60°F.131

F.1.1.2 Cetane Number

One key property of diesel fuel is the ease with which it ignites, quantified by the cetane 

number, with higher numbers indicating greater ignitability. The cetane number is the standard 

measure of fuel ignition characteristics when injected into a diesel engine. It relates to the delay 

between when fuel is injected into the cylinder and when ignition occurs. Higher cetane 

number indicates shorter times between injection of the fuel and its ignition. Good ignition 

from a high cetane number assists in easy starting, starting at low temperature, low ignition 

pressures, and smooth operation with lower knocking characteristics.131 Large, slower speed 

engines, as used in locomotive and marine applications, are more tolerant of poor-quality 
260

fuels.146

F.1.1.3 Distillation Range

Distillation range refers to the range of boiling points of different liquid fractions of the 

fuel, which are observed when separating the fuel into its components. The distillation range is 

generally expressed in terms of the temperatures at which 10 percent (T10), 50 percent (T50), 

and 90 percent (T90) of the fuel will be evaporated. The highest temperature recorded during 

distillation is called the end point. However, because a fuel’s end point is difficult to measure 

with good repeatability, 90 percent distillation point of fuel is commonly used.131

F.1.1.4 Aromatic Content

Aromatic content is characterized by the presence of the benzene family in hydrocarbon 

compounds in the fuel. Aromatic compounds include heavier compounds such as toluene, 

xylene, and naphthalene.131

F.1.1.5 Heating Value

The heating value of a fuel is the enthalpy of reaction for combustion of the fuel. Thus, 

the heating value is the amount of energy released when the fuel is completely burned in a steady 

flow process. The magnitude of the heating value depends on the fate of H2O in the combustion 

products. In most real systems, the H2O leaves the engine or combustor in the vapor phase. For 

this situation, the Lower Heating Value (LHV) is used. However, in principle, one could 

condense the water vapor and recover the latent heat of vaporization associated with this phase 

change. If this could be done, then the total heating value would be the sum of the LHV and the 

latent heat of condensation, which is referred to as the Higher Heating Value (HHV).131

F.1.1.6 Viscosity

Viscosity is a measure of the resistance of a fuel to shear or flow, and is a measure of the 

fuel's adhesive/cohesive or frictional properties. 131

F.1.2 Diesel Fuel 

Distillate fuel oil is a classification for one of the distillation fraction of petroleum. It 

includes diesel fuels and fuel oils. Diesel fuel is a complex mixture of many different 

hydrocarbons with a distillation range of 350 to 640 °F,131 with carbon numbers in the range of 

C3 to C25, and with an average molecular weight of about 200.132 Current commercial diesel 

fuels in the United States include No. 1 diesel fuel, No. 2 diesel fuel, No. 4 diesel fuel, and 

marine gas oil.111,146 Marine gas oil is one kind of bunker fuel that is used for small and 
261

medium sized marine engines.111 No. 1 diesel fuel is usually used in city buses. No. 2 diesel 

fuel is used in high-speed diesel engines that are operated under load conditions, such as those in 

trucks and railroad locomotives. No. 4 diesel fuel is usually used in industrial plants and in 

commercial burner installions, but is also used for low- and medium-speed diesel engines.147 

These fuels can differ with respect to cetane number, aromatic content, sulfur level, levels of 

contaminants (e.g., metals), and viscosity.146 The major fuels related to freight transportation 

are No. 2 diesel fuel and marine gas oil. Major properties of No. 2 diesel fuel, the fuel used in 

trucks and locomotives, are listed in Table F-1. The important differences between No. 2 diesel 

fuels and marine gas oil are sulfur content and viscosity. The sulfur content of marine gas oil is 

generally about 1.5-2.0% mass, but the sulfur content of No. 2 diesel fuel is generally about 

0.05% mass or lower because sulfur content of No. 2 diesel fuel is restricted by state and federal 

regulations. The maximum viscosity of marine gas oil is about 6.0-11.0 at 104°F, and the 

density of marine gas oil is about 0.89-0.90 at 60°F.148

Table F-1. Major Properties of No. 2 Diesel Fuel.131,132,149

Property Value 

Chemical formula C3 to C25

Physical state Liquid 

Molecular weight ≈200 

Carbon 84–87 (86.4) 

Hydrogen 13–16 (13.4) Composition 

(weight %) Oxygen 0 

Specific gravity @ 60 ̊ F 0.81–0.89 (0.84) 

Cetane Number 40-55 (44) 

10% point, °F 410 to 430 

50% point, °F 490 to 520 Distillation 

range 90% point, °F 585 to 620 

Aromatics, vol% 30 

Higher (liquid fuel-liquid water) BTU/lb 19,200-20,000 

Lower (liquid fuel-water vapor) BTU/lb 18,000-19,000 

Higher (liquid fuel-liquid water) BTU/gallon, 138,690-138,700 

(138,690) Heating value 

Lower (liquid fuel-water vapor) BTU/gallon @ 

60 ̊F 128,400 

Viscosity, Centipoise @ 60 ̊F 2.6-4.1 

Freezing point, F ̊ -40–30 

Reid vapor pressure, psi 0.2 

Latent heat of BTU/lb @ 60 ̊F ≈100 

vaporization BTU/gallon @ 60 ̊F ≈700 
262

F.1.3 Jet Fuel 

Jet fuel is a refined petroleum product used in jet aircraft engines.111 Jet fuel includes 

kerosene-type jet fuel and naphtha-type jet fuel.150 Kerosene-type jet fuel, including Grades 

JP-5 and JP-8, is a kerosene-based product that has a distillation temperature of 400 degrees 

Fahrenheit at the 10-percent recovery point and a final boiling point of 572 degrees Fahrenheit 

and meeting ASTM Specification D 1655 and Military Specifications MIL-T-5624P and 

MIL-T-83133D.147 MIL-T-5624P is for JP-5 and MIL-T-83133D is for JP-8.151

Naphtha-type jet fuel, usually being Grade JP-4, is a fuel used primarily for military 

turbojet and turboprop aircraft engines because it has a lower freeze point than other aviation 

fuels and meets engine requirements at high altitudes and speeds. It has 20 to 90 percent 

distillation temperatures of 290 degrees to 470 degrees Fahrenheit, and meeting Military 

Specification MIL-T-5624L. It is 147,151

From a chemistry standpoint, the composition of jet fuels is quite similar to that of diesel 

fuel, kerosene or light distillates including home heating oil. Jet fuels are relatively safe to 

transport, store and handle when compared with gasoline. All of these jet fuels have about the 

similar heating values (around 18,400 BTU/lb), but JP-4 is more flammable than JP-8 and both 

JP-4 and JP-8 are more flammable than JP-5. The Navy uses JP-5 since shipboard use requires 

a greater degree of safety. JP-8+100 is a new product that contains an additive package 

designed to increases the temperature range over which the fuels remains thermally stable by 100 

°F. While commercial aircraft still use JP-4, the Navy now uses JP-5, and the Air Force uses 

JP-8+100. 152 Major properties of jet fuel are listed in Table F-2. 

Table F-2. Major Properties of Jet Fuel151,153

Property JP-4 JP-5 JP-8 

Carbon - - - 

Hydrogen 13.5 13.4 13.4 Composition 

(weight %) Oxygen - - - 

Density (kg/L) @ 15 ̊C 0.751-0.802 0.788-0.845 0.775-0.840 

Cetane Number - - 

10% point, °C - 205 205 

20% point, °C 145 - - 

50% point, °C 190 - - 

90% point, °C 245 - - 

Distillation 

range 

End point, °C 270 300 300 

Aromatics, vol% 25.0 25.0 25.0 

Heating value* Lower (liquid fuel-water 

vapor) BTU/lb 18,400 18,300 18,400 

Viscosity, Centipoise @ 20 ̊C - 8.5 8.0 

Freezing point, F ̊ -72 -61 -53 

Vapor pressure (psi) @ 100 ̊F 2.0-3.0 - - 
263

F.1.4 Biodiesel 

Biodiesel is defined as the mono alkyl esters of long-chain fatty acids derived from 

vegetable oils or animal fats, and was developed for use in compression-ignition engines.154 

Major properties of 100% soybean-based biodiesel are listed in Table F-3. 

Table F-3. Major Properties of B100 Biodiesel Blend Stock.131,154 

Property Value 

Chemical formula C12 to C22

Physical state Liquid 

Carbon 76.9-77.3 

Composition (weight %) Hydrogen 11.8-12.1 

Oxygen 11.0 

Specific gravity @ 60 ̊F 0.886 - 0.89 

(average 0.888) 

Cetane Number 47.5 

10% point, °F 631.4 

Distillation range 50% point, °F 636.8 

90% point, °F 645.8 

Aromatics, vol% 0 

Higher (liquid fuel-liquid water) 

BTU/lb 17,111 

Higher (liquid fuel-liquid water) 

BTU/gallon 126,789 Heating value* 

Lower (liquid fuel-water vapor) 

BTU/lb 15,993 

Viscosity, Centipoise @ 104 ̊F 4.1 

Boiling temperature, F ̊ 573 

* Higher heating value of biodiesel is about 17,111 BTU/lb, or 126,789 BTU/gallon. 

gallon

126,789 BTU

gallon

3.785 L

L

888 g

453.6 g

lb

lb

BTU 17,111 × × × =

F.1.5 Residual Fuel Oil 

Residual fuel oil is a general classification for the heavier oils that remain after the 

distillate fractions are distilled away in refinery operations. It includes No. 5 and No. 6 fuel oils 

and is used for large steam boilers and, with fuel preheating, for very large compression ignition 

engines, such as ocean-going ships.111,147 No. 5 fuel oil is a residual fuel oil of medium 

viscosity, and is used in steam-powered vessels in government service and inshore power plants. 

No. 6 fuel oil includes marine residual fuel oil, another kind of bunker fuel (called Bunker C fuel 

oil), and is used for electric power plants, space heaters, marine vessels, and various industrial 

purposes.147 Major properties of marine residual fuel oil are listed in Table F-4. 
264

Table F-4. Major Properties of Marine Residual Fuel Oil.147,148,155 

Property Value 

Specific gravity @ 60 ̊F 0.991 

Sulfur content, % mass 5 

Higher heating value, BTU/gallon 149,700 

Higher heating value, BTU/lb 19,011 

Viscosity, Centipoise @ 122 ̊F 340 

Flash point, F ̊ 140 

F.1.6 Natural Gas 

Natural gas is a naturally occurring mixture of hydrocarbon and non-hydrocarbon gases 

found in porous geologic formations beneath the earth's surface, often in association with 

petroleum. Natural gas is a fossil fuel composed almost entirely of methane, but does 

contain small amounts of other gases, such as ethane, propane, butane and pentane.156 

Major properties of natural gas are listed in Table F-5.157

Table F-5. Major Properties of Natural Gas.132,145,156,157 

Property Value 

Methane concentration, % Volume 80 - 99 

Ethane concentration, % Volume 2.7 - 4.6 

Nitrogen concentration, % Volume 0.1 - 15 

Carbon dioxide concentration, % Volume] 1 - 5 

Sulphur concentration, ppm, mass <5 

Physical state Gas 

Average Molecular weight 17-20 

Carbon 73.3 

Hydrogen 23.9 Composition 

(weight %) Oxygen 0.4 

Specific gravity @ 59  ̊F (15  ̊F) 0.72-0.81 

Lower heating value, MJ/kg 38-50 

Lower heating value, BTU/lb 16,335-21,493 

(21,300) Heating value 

Lower heating value, BTU/ft3 1,031 

Freezing point, F ̊ -296 

Reid vapor pressure, psi 2400 

APPENDIX F.2 CO2 Emissions Coefficients for Different Fuels 

The total CO2 emissions on a per energy basis depend on the weight percent of carbon in 
265

the fuel, the combustion efficiency, and the heating vale of the fuel.131 

F.2.1 Diesel Fuel 

The carbon coefficient of distillate fuel oil, including diesel fuel, is estimated to be 19.95 

million metric tons carbon per quadrillion BTU.13 Based on the transformation shown below, 

the CO2 emissions coefficient of diesel fuel is estimated to be 0.0808 tons CO2 eq. per 106 BTU.

BTU

tons CO

BTU

quadrillion BTU

carbon

CO

metric tons

tons

quadrillion BTU

metric tons carbon

6

2

15

6 2

10

0.0808

12 10

1.105 44

19.95×10 × × × =

F.2.2 Jet Fuel 

The carbon coefficient of jet fuel is estimated to be 19.33 million metric tons carbon per 

quadrillion BTU.13 Based on the transformation shown below, CO2 emissions coefficient of jet 

fuel is estimated to be 0.0783 tons CO2 eq. per 106 BTU.

BTU

tons CO

BTU

quadrillion BTU

carbon

CO

metric tons

tons

quadrillion BTU

metric tons carbon 6

2

15

6 2

10

0.0783

12 10

1.105 44 19.33×10 × × × =

F.2.3 Biodiesel 

The net life-cycle CO2 emissions of petroleum diesel are about 0.0938 tons CO2 eq. per 

106 BTU. The net life-cycle CO2 emissions of B20 biodiesel is about 0.0869 tons CO2 eq. per 

106 BTU.61 The net life-cycle CO2 emissions reduction is about 0.0069 tons CO2 eq. per 106

BTU. 

F.2.4 Residual Fuel Oil 

The carbon coefficient of residual fuel oil is estimated to be 21.49 million metric tons 

carbon per quadrillion BTU.13 Based on the transformation shown below, CO2 emissions 

coefficient of residual fuel oil is estimated to be 0.087 tons CO2 eq. per 106 BTU.

BTU

tons CO

BTU

quadrillion BTU

carbon

CO

metric tons

tons

quadrillion BTU

metric tons carbon

6

2

15

6 2

10

0.0870

12 10

1.105 44

21.49×10 × × × =

F.2.5 Natural Gas 

The carbon coefficient of natural gas is estimated to be 14.47 million metric tons carbon 

per quadrillion BTU.13 Based on the transformation shown below, CO2 emissions coefficient of 

natural gas is estimated to be 0.0586 tons CO2 eq. per 106 BTU.

BTU

tons CO

BTU

quadrillion BTU

carbon

CO

metric tons

tons

quadrillion BTU

metric tons carbon

6

2

15

6 2

10

0.0586

12 10

1.105 44

14.47×10 × × × =
266

F.2.6 Comparison of CO2 Emissions Coefficients of Different Fuels 

The CO2 emissions coefficients of different fuels are listed in Table F-6. 

Table F-7. CO2 Emissions Coefficients of Different Fuels 

Fuel Name Diesel Fuel Jet Fuel Residual Fuel Oil Natural Gas 

CO2 Emissions 

Coefficient 

(tons CO2 eq./ 

106 BTU) 

0.0808 0.0783 0.0870 0.0586 

APPENDIX F.3 Average Unit Costs for Different Fuels 

For calculating the average energy unit cost estimate and energy cost reduction in the 

standardized reporting tables, average unit costs of different fuels should be estimated first, and 

these unit costs are described in this section. 

F.3.1 Diesel Fuel 

Diesel price is 2.56 US Dollars per gallon, which was estimated by U.S. Department of 

Energy for the diesel prices of the second season (April to June) of 2005.114 Also, heating value 

of diesel is 138,690 BTU per gallon.13 Therefore, the average fuel cost estimate is $18.46/106

BTU. 

BTU BTU

gallon

gallon 6 10

$18.46

138,690

$2.56 =





 







×















F.3.2 Jet Fuel 

Average market price of jet fuel is about 2.10 US Dollars per gallon, which was estimated 

by U.S. Energy Information Administration for the jet fuel prices of September 2005.158 Also, 

heating value of jet fuel is estimated to be 134,000 BTU/gallon. Therefore, the average fuel 

cost estimate is $15.70/106 BTU. 

BTU BTU

gallon

gallon 6 10

$15.70

134,000

$2.10 =





 







×















F.3.3 Biodiesel 

Wholesale B100 biodiesel price around April 2005 was 2.82 US Dollars per gallon.137 

Also, heating value of B100 biodiesel is estimated to be 126,789 BTU/gallon. Therefore, the 
267

average fuel cost of B100 Biodiesel is estimated to be $22.2/106 BTU. 

BTU BTU

gallon

gallon 6 10

$22.2

126,789

$2.82 =















×















F.3.4 Residual Fuel Oil 

Average residual fuel oil price with sulfur greater than 1% is about 1.168 US Dollars per 

gallon, which was estimated by U.S. Energy Information Administration for the residual fuel oil 

prices of September 2005.159 Also, heating value of residual fuel oil is estimated to be 149,700 

BTU/gallon. Therefore, the average fuel cost estimate is $7.80/106 BTU. 

BTU BTU

gallon

gallon 6 10

$7.80

149,700

$1.168 =





 







×















F.3.5 Natural Gas 

Average natural gas price for city gate is about 10.26 US Dollars per thousand cubic feet, 

estimated by U.S. Energy Information Administration for the natural gas prices of September 

2005.159 Also, heating value of natural gas is estimated to be 1,031 BTU per cubic feet.145 

Therefore, the average fuel cost estimate is $9.95/106 BTU. 

F.3.6 Comparison of Average Unit Cost of Different Fuels 

The average unit cost of different fuels is listed in Table F-8. 

Table F-8. Average Unit Cost of Different Fuels 

Fuel Name Diesel Fuel Jet Fuel Biodiesel Residual Fuel Oil Natural Gas

Average Unit Cost 

($/106

 BTU) 

18.46 15.70 22.2 7.8 9.95