CONTENTS Chapter 1 Background 1 1.1 Problem Statement and Research Objective 1 1.2 Scope of the Research Project 1 Chapter 2 Research Approach 2 Chapter 3 Research Findings and Products 6 3.1 GSE Types and Functions 6 3.1.1 Types and Functions 6 3.1.2 GSE Use Considerations 6 3.1.3 GSE Suppliers 11 3.2 Federal Regulations and Programs Applicable to GSE 11 3.2.1 Federal Regulations11 3.2.2 Non-road Engine Emission Standards (Compression and Spark Ignition) 14 3.2.3 On-Road Engine Emission Standards (Compression and Spark Ignition) 15 3.2.4 Emission Standards in the State of California 16 3.2.5 State Implementation Plans and Emission Budgets 16 3.2.6 FAA's Voluntary Airport Low Emission Program 17 3.2.7 Other Grant Programs 18 3.3 Air Emission Mitigation Strategies Applicable to GSE 19 3.3.1 Equipment-Related Approaches 19 3.3.2 Alternative-Fuel GSE 20 3.3.3 Operations/Maintenance-Related Approaches 21 3.3.4 Other Approaches 22 3.3.5 Airport-Specific GSE Emission Reduction Measures 22 3.4 Economic and Environmental Challenges and Considerations with Alternative-Fuel GSE 22 3.4.1 Economic Considerations and Challenges 22 3.4.2 Environmental Considerations and Challenges 43 3.4.3 Environmental Considerations and Challenges with Other Environmental Media 50 3.5 GSE Tutorial 53 3.6 GSE Inventory 54 3.6.1 Airport Field Surveys and Data Evaluation 54 3.6.2 Airline-Provided Data 61 3.6.3 Existing GSE Data Sets 65 3.6.4 National GSE Inventory Recommendation 66 3.7 Economic Factors 66 3.7.1 Alternative Fuels 66 3.7.2 Infrastructure 66 3.7.3 Purchasing versus Retrofit 67 3.7.4 Qualitative Considerations 68 Acronyms and Abbreviations 71 References 75 A-1 Appendix A List of Available GSE Products B-1 Appendix B Air Pollutant Emission Factors for GSE