Airport Ground Support Equipment (GSE): Emission Reduction Strategies, Inventory, and Tutorial (2012)

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6The essential outcomes and products of the research are presented in the following sections. 3.1 GSE Types and Functions Prepared in conjunction with Task 1, the following materials identify the different kinds of GSE and how they are used at airports of varying functions (i.e., hub and non-hub), sizes, and locations. 3.1.1 Types and Functions Most GSE are typically associated with the servicing of aircraft during the airport turnaround process consisting of the ground operations that are undertaken from the time the rubber blocks (chocks) are placed in front of the aircraft wheels until the time the blocks are removed and the aircraft is ready to leave the gate. During this period, there are a number of tasks that are per- formed including loading and unloading passengers and baggage, aircraft cleaning and main- tenance, refueling and replenishment of provisions, and other similar services. Other common GSE functions pertain to the servicing and maintenance of the airside infrastructure and air- field of the airport. For the purpose of this research, GSE types are categorized by the use of the equipment as follows: • Providing ground power and air conditioning to an aircraft; • Moving an aircraft (e.g., out of a gate, to/from maintenance); • Servicing an aircraft between flights (e.g., replenishing supplies, deicing, etc.); • Loading/unloading passengers; • Loading and unloading baggage and cargo; and • Servicing the airport’s ramps, runways, and other areas (e.g., snow removal and lawn main- tenance equipment). A summary description of the GSE types and functions is provided in Table 3-1. Notably, the types of GSE are limited to “powered” GSE and do not include non-motorized equipment such as baggage carts, fuel carts, mobile storage tanks, etc. 3.1.2 GSE Use Considerations Importantly, not every type of GSE in Table 3-1 is used at every airport in the United States. Factors such as airport type (e.g., general aviation, commercial), the amount of activity at an air- port, the size/use of the aircraft using the airport (e.g., wide body, narrow body), tenant use (i.e., C h a p t e r 3 Research Findings and Products

research Findings and products 7 Category Category Description GSE GSE Description Ground power/air conditioning Used to help start the engines, operate instruments and provide for passenger comfort (e.g., lighting, air conditioning) while an aircraft is on the ground. Air starter Vehicle with a built-in engine which, when aircraft engines are started, provides air for the initial rotation of a large engine. Ground power unit (GPU) Mobile generators that provide power to parked aircraft when an aircraft’s engines are not in use. Typically not used when an airport has gate power systems [i.e., 400 Hertz (Hz)]. Can also be used to start aircraft engines. Air conditioning units Also referred to as air carts, these units provide conditioned (i.e., cooled and heated) air to ventilate parked aircraft. At some larger airports, individual packaged assemblies or centralized electrical-powered pre-conditioned air (PCA) systems are used. Aircraft movement Although an aircraft’s engines are capable of moving an aircraft in reverse, this is not typically done for aircraft with jet engines due to the resulting “jet blast” that would occur at the back of the aircraft. For this reason, and others, pushback tugs/tractors are used to maneuver aircraft away from (i.e., out of) gates. Pushback tugs/tractors Used to move an aircraft out of a gate when a pilot is given clearance to taxi to a runway. May also be used to move an aircraft to various locations on an airport (e.g., maintenance hangars). There are two types of pushback tugs/tractors: (1) conventional and (2) towbarless. Conventional tugs use towbars that are connected to an aircraft’s noise wheel. Towbarless tractors scoop up the noise wheel and lift it off the ground. Aircraft service Aircraft service activities include replenishing supplies and aircraft refueling. Catering truck Typically owned and operated by airlines and companies that specialize in airline catering (e.g., preparing and supplying packaged food). Services provided include removal of unused food/drinks and loading of these items for the next flight. Cabin service vehicles The main cabin service activities are cleaning the passenger cabin and replenishing items such as soap, pillows, and blankets. Table 3-1. GSE types and functions. (continued on next page)

8 airport Ground Support equipment (GSe): emission reduction Strategies, Inventory, and tutorial Category Category Description GSE GSE Description Potable water trucks/carts These trucks provide drinkable water to an aircraft. Aviation fuel trucks, hydrant dispenser trucks/carts Two methods are used to fuel aircraft. The first dispenses fuel from a fuel truck/tanker directly to an aircraft’s tank(s). The second method of dispensing fuel is used at airports with underground fueling systems and employs hydrant trucks/carts as “connectors” between the underground fueling system and aircraft. Hydrant pit cleaners Used at airports with underground fueling systems. Flushes and cleans hydrant pits. Maintenance vehicles Various types of vehicles are used to provide aircraft maintenance service. These vehicles are used by airport and/or airline employees to travel to/from maintenance facilities and an aircraft in need of repair. Deicers Vehicles that are used to transport, heat, and spray deicing fluid on an aircraft prior to departure. Passenger loading/ unloading Methods vary depending on airport, aircraft, and available airport equipment/facilities. Two methods are used to board passengers onto large aircraft—boarding stairs and jet bridges. Boarding stairs Whether towed, pushed into position, or fixed to a truck, boarding stairs provide a means of loading and unloading passengers at hardstands (i.e., remote parking positions) and in the absence of jet bridges. Buses On the airside of a large airport, buses may be used to transport passengers and employees from terminal to terminal (or aircraft). Referred to as “people movers,” “mobile passenger lounges,” and “moon buggies." Lavatory service vehicles Used to flush aircraft lavatory systems. Small commuter and regional aircraft used for short flights may not be equipped with on-board lavatories. Table 3-1. (Continued).

research Findings and products 9 Category Category Description GSE GSE Description Baggage/cargo handling Passenger baggage/some cargo must be transferred to/from gates and from gate to gate. Cargo-only aircraft typically have one or more large doors to facilitate loading/unloading of goods. Baggage tugs Most recognizable type of GSE at an airport. These vehicles are used to transport luggage, mail, and cargo between an aircraft and the airport terminal and/or processing/sorting facilities. Belt loaders Used to load and unload baggage and cargo into/from an aircraft. Cargo/container loaders Used to load and unload the cargo on an aircraft that is within a container or on a pallet. Cargo transportation/ tractors Used to load and unload cargo but are primarily used to move cargo from one airport location to another. Forklifts Cargo is moved primarily by forklifts within airport cargo handling facilities. Conveyors At larger airports, there has been a recent trend to move baggage between concourse collection areas and to/from the concourse collection areas and the terminal baggage claim areas using conveyor systems. Installation of such conveyor systems can significantly reduce the run time for baggage tugs and/or reduce the number of baggage tugs at an airport. Airport service Various types of GSE are used by ground crews (airline and/or airport) to service airports. Snow removal equipment Airports use snow removal equipment to keep runways, taxiways, and ramp areas free of snow and ice. Can include snowplows, snow sweepers, and snow blowers. Snow sweepers, typically used in areas with low snow tolerance (i.e., runways), use brushes to remove thin layers of snow from pavement services. Snow blowers are sometimes used instead of snowplows. This type of vehicle uses spinning blades that force the snow out of a “funnel” on the top of the blower. Table 3-1. (Continued). (continued on next page)

10 airport Ground Support equipment (GSe): emission reduction Strategies, Inventory, and tutorial hub or non-hub), an airport’s geographic location (i.e., warm or cold climate), available infra- structure (e.g., number of gates, underground fueling system), and airport capacity all influ- ence not only the type of GSE but also the number of pieces of GSE in use. Notably, equipment “engine on”/run times can also be affected by these factors. These factors may affect the type and quantity of GSE at airports as follows: • Airport type: The number and type of GSE in use at an airport is directly related to the type of airport (which also determines the type/size of aircraft using the airport). At an airport that exclusively serves general aviation aircraft, one would not expect to find a significant amount or a wide variety of GSE. By comparison, a large commercial airport located in a metropolitan area typically has a large number of daily operations that requires an extensive inventory of GSE be readily available. • Airport activity: Generally, the greater the number of operations at an airport, the more GSE will be required to provide an acceptable level of service. • Aircraft size/use: Large and medium size passenger air carrier aircraft (e.g., B777, B747, MD11) are referred to as “wide body” aircraft. These aircraft may carry passenger baggage in containers and have a significant amount of cargo to be loaded/unloaded. Smaller passenger air carrier aircraft (e.g., B737, A319) are referred to as “narrow body” aircraft. The amount of passenger baggage and cargo onboard this size aircraft will require smaller or fewer types of GSE to com- plete necessary gate handling procedures. Regional/business jets and turboprop aircraft (such as the Embraer Legacy 600/145 and Beechcraft Super King Air) have built-in passenger stairs and typically do not carry cargo. Finally, general aviation propeller aircraft and helicopters carry limited baggage, if any, and no cargo and require only limited handling at airports. • Hub/non-hub: Because more aircraft operations occur at hub airports than non-hub airports, more GSE are typically required. Further, while the use of the equipment would be the same regardless of the airport designation (i.e., baggage tugs would still be used to transfer baggage), the number of pieces of equipment required may be more if scheduling (turnaround) times are limited (i.e., more tugs are needed to transfer baggage to individual flights). • Climate: In cold climates with freezing temperatures and precipitation, aircraft and airport sur- faces must be deiced and/or snow must be removed. To remove ice from aircraft, deicers are used. Category Category Description GSE GSE Description Foreign object debris (FOD) removal The removal of FOD can be accomplished using mechanical systems (power sweeper trucks, vacuum systems, and jet air blowers) and non-mechanical systems (e.g., tow-behind trailers equipped with brushes, magnetic bars). Bobtail trucks A bobtail is an on-road truck that has been modified to tow trailers and equipment. Bobtails are also used at some airports to plow snow. Miscellaneous equipment Includes the non-road equipment used by an airport’s ground crew to maintain the airport airside environs. This GSE includes generators and lawn mowers. Select on-road equipment such as tow trucks (pictured) can also fall into this category. Table 3-1. (Continued).

research Findings and products 11 Among other factors, the number of deicing vehicles that are required depends on the severity and frequency of conditions requiring deicing and the number of operations at an airport. • Infrastructure: The available infrastructure at an airport can negate the need for certain types of GSE or reduce an airport’s dependence on some GSE. As described in Table 3-1, aircraft are refueled using one of two methods: (1) fuel tankers and (2) underground fueling systems. If an airport has an underground fueling system, fuel is transferred with a hydrant vehicle or a hydrant cart and fuel tankers are not needed. • Capacity: An airport’s available capacity can also affect the type and number of GSE in use at an airport. For example, if the number of operations in a given time period exceeds the number of available gates, airports may “hardstand” the “extra” aircraft. A hardstand is a hard surface area that is typically located away from an airport’s concourses or terminal. Depending on the size of the aircraft, hardstanding an aircraft will require the use of buses (or “mobile lounges”) to transport passengers to/from the aircraft and the use of mobile ground power/ air conditioning units for the purpose of performing instrument checks, starting engines, and passenger comfort. Table 3-2 provides a summary list—by airport type, climate, and intended purpose/utility— of the most common types of GSE used at airports. 3.1.3 GSE Suppliers During the course of the project, the research team contacted more than 40 GSE suppliers. Representing vendors that manufacture GSE and distribute and/or rent new and refurbished GSE, these companies provide more than 550 models of various types of GSE. For informational purposes, the types of GSE currently manufactured/distributed by these and other vendors are listed in Appendix A. 3.2 Federal Regulations and Programs Applicable to GSE Prepared in support of Task 2, this section identifies and describes the federal regulations and initiatives pertinent to GSE. However, because several state- and local-level regulations and programs are noteworthy, they are also briefly reported upon here. 3.2.1 Federal Regulations The federal CAA provides the underlying authority for the protection of the public health and welfare and the environment from air pollution nationwide. It also prescribes the regulation of air emissions from the vast majority of man-made sources, including GSE. The overriding responsibility for the management of ambient (i.e., outdoor) air quality across the United States is principally vested to the U.S. Environmental Protection Agency (EPA). As a means to carry out and fulfill these functions, the U.S. EPA has promulgated National Ambient Air Quality Standards (NAAQS) for six “criteria” air pollutants [i.e., carbon monoxide (CO), lead (Pb), ozone (O3), particulate matter with an aerodynamic diameter of 10 microm- eters or less (PM10) and an aerodynamic diameter of 2.5 micrometers or less (PM2.5), nitrogen dioxide (NO2), and sulfur dioxide (SO2)]. For compliance and air quality management purposes, all areas of the United States are designated with respect to their adherence to the NAAQS. Specifically, areas that meet the NAAQS are designated as “attainment” and those that do not meet the NAAQS are called “nonattainment” (areas in transition are designated “maintenance”). In nonattainment areas, state implementation plans (SIPs), developed by state and local agen- cies for U.S. EPA approval, identify the policies, control measures, and time frames that will be

12 airport Ground Support equipment (GSe): emission reduction Strategies, Inventory, and tutorial implemented to achieve the NAAQS. Notably, land under tribal government may prepare and submit a tribal implementation plan (TIP). The U.S. EPA also establishes emission standards (i.e., limitations on the quantity of pol- lutants emitted) from most stationary and mobile sources of criteria air pollution (and their precursors). Typically, stationary sources represent “smoke-stack” or permanent (i.e., “fixed”) installations and mobile sources are characteristically movable or transportable. A third general category of emissions are area sources comprising construction, agricultural, and other similar activities. The U.S. EPA also sets limitations on emissions of 187 compounds or compound categories of hazardous air pollutants (HAPs). GSE Type Purpose and Utility Airport Climate CharacteristicsH N W C Air conditioner Provides conditioned air to ventilate and cool parked aircraft. Used less in cool climates and at airports with gate air conditioner units. Air starter Provides large volumes of compressed air to an aircraft’s main engines for starting. Used less at airports with gate electricity. Used for commuter aircraft. Baggage/cargo tractors Used to tow baggage carts or freight. Most common GSE type and amenable to alternative fuel power. Belt loaders Mobile conveyor belts used to move baggage between the ground and the aircraft hold. Used mostly on narrow and medium body passenger aircraft. Buses Shuttles passenger and airport personnel between facility locations. Used mostly at hub airports without people mover systems. Cabin service truck Used for cleaning the cabin and replenishing supplies. Commonly classified as on-road vehicles. Cars/pickup trucks Move airport personnel around facility for administrative and maintenance purposes. Commonly classified as on-road vehicles. Carts Used as personnel carriers. Small gasoline- or electric- powered non-road vehicles. Catering vehicle Used to restock drinks/food for passenger meals. Commonly classified as on-road vehicles. Container loader Used to load large containers on to large cargo and other aircraft Used for air cargo and wide- body passenger aircraft. De/anti-icing vehicles Used to remove ice from aircraft prior to departure. Used more at cold climate airports. Forklifts Used to move heavy cargo. Used for air cargo and wide- body passenger aircraft. Fuel trucks Used to fuel aircraft in the absence of a hydrant system Used less at airports with fuel hydrants. Ground power units Mobile generator units that supply aircraft with electricity while parked. Used less at airports with gate electricity. Used for commuter aircraft. Hydrant cart/trucks Used to connect underground fueling system to aircraft. Replacements for fuel trucks at airports with hydrants. Lavatory service vehicles Used to remove waste /non- potable water from aircraft lavatories. Commonly classified as on-road vehicles. Passenger stands Provides passenger access/egress to aircraft Used mostly for air cargo, chartered, and commuter aircraft. Sweepers Used to clean gate area and aprons. Diesel-powered, specialty vehicles. Tow tugs and pushback tractors Use to tow and push aircraft in the terminal, ramp, and hangar areas. Most common GSE type and amenable to alternative fuel power. Water trucks Used to supply water to aircraft. Commonly classified as on-road vehicles. H – Hub airports, N – Non-hub airports; W – Warm climate, C – Cold climate; Common use, Less use Table 3-2. Common types of GSE and use considerations.

research Findings and products 13 GSE are commonly classifiable under two subcategories of mobile sources: (1) non-road vehi- cles (i.e., engines and equipment that would not be expected to travel on public roadways) and (2) on-road motor vehicles (i.e., vehicles that are licensed to travel on public roadways). In some instances, GSE may have on-road capabilities but are used in non-road functions (i.e., cabin service trucks). The emission standards developed by the U.S. EPA to date have typically been much more stringent (i.e., having much lower allowable emission rates) for on-road vehicles than for non- road equipment. Many GSE types (e.g., catering trucks, cabin service trucks, and crew vans) are built with engines that meet the on-road emission standards. Other GSE types (e.g., belt loaders, aircraft tugs, and bag tugs) are typically built with non-road engines and therefore subject to non-road emission standards. Importantly, the CAA preempts states from adopting or enforcing their own on-road and non-road emission standards, with California being the exception. Tables 3-3 and 3-4 list and summarize the primary federal statutes and programs relevant to the manufacture, ownership, and operation of GSE. Statute/Program Statute/Program Section Airport GSE Relevance CAA Title I: Part A, Air Quality and Emission Limitations 109 – National Ambient Air Quality Standards 110 – Implementation Plans Sets standards for health-based air pollutant concentrations in ambient air. Requires states to develop implementation plans to control emissions of criteria pollutants to attain and maintain the National Ambient Air Quality Standards. CAA Title I: Part D, Plan Requirements for Nonattainment Areas 182 – Plan Submissions and Requirements 187 – Plan Submissions and Requirements Establishes inspection/maintenance programs for on-road vehicles in ozone nonattainment areas. Establishes inspection/maintenance programs for on-road vehicles in carbon monoxide nonattainment areas. CAA Title II: Part A: Motor Vehicle Emission and Fuel Standards 202 – Emission Standards for New Motor Vehicles or New Motor Vehicle Engines 211 – Regulation of Fuels 213 – Nonroad Engines and Vehicles Sets engine exhaust emission standards for “on-road” vehicles (cars, vans, catering vehicles, etc.). Sets limitations on the use of additives and the levels of certain compounds, including sulfur, in motor vehicle fuels. Sets engine exhaust standards for non-road vehicles (e.g., belt loaders, tow tugs, forklifts, etc.). Vision 100 Century of Aviation Reauthorization Act: FAA Voluntary Airport Low Emission Program 121 – Low-Emission Airport Vehicles and Ground Support Equipment 151 – Increase in Apportionment for, and Flexibility of, Noise Compatibility Planning Programs 158 – Emission Credits for Air Quality Projects 159 – Low-Emission Airport Vehicles and Infrastructure Provides funding for alternative-fuel vehicles as well as low-emission equipment and infrastructure. Energy Policy Act of 2005 National Clean Diesel Emissions Reduction Program, also called the Diesel Emissions Reduction Act (DERA), and the SmartWay Program Provides funding assistance to support the deployment of U.S. EPA-verified and certified technologies to reduce diesel- related emissions. Table 3-3. Summary of relevant federal statutes and programs pertaining to GSE.

14 airport Ground Support equipment (GSe): emission reduction Strategies, Inventory, and tutorial 3.2.2 Non-road Engine Emission Standards (Compression and Spark Ignition) Non-road vehicles (including non-road engines and the associated equipment) constitute a broad array of vehicle and equipment types, including aircraft, watercraft, locomotives, rec- reational vehicles, construction vehicles, farm equipment, and GSE, to name a few. The non- road engines generally fall into two broad classes: (1) compression-ignition (CI) engines and (2) spark-ignition (SI) engines. Typically, non-road CI engines are fueled with diesel while non- road SI engines are traditionally fueled with a more volatile fuel, such as gasoline. With the emergence of alternative fuels and technologies, other fuels are now becoming more common as discussed in Section 3.3.2 (Alternative-Fuel GSE). Compression-Ignition Engines Federal emission standards for non-road CI engines have been established for non-methane hydrocarbons (NMHC), oxides of nitrogen (NOx), particulate matter (PM), CO, and smoke out- put. The U.S. EPA has organized these emissions standards into classes (or tiers) based on the date Table 3-4. Summary of federal regulations potentially applicable to airport GSE. Citationa Title Airport GSE Relevance 40 CFR 80 Regulation of Fuels and Fuel Additives Sets specifications and limitations on fuels and additives for engines used in on-road and non-road vehicles including airport GSE. 40 CFR 85 Control of Air Pollution from Mobile Sources Contains emission performance warranty and other information for engines used in on-road vehicles including airport GSE. 40 CFR 86 Control of Emissions from New and In- Use Highway Vehicles and Engines Contains exhaust emission standards for engines used in on-road vehicles including airport GSE. 40 CFR 88 Clean-Fuel Vehicles Contains exhaust emission standards for centrally fueled fleets such as on-road airport GSE in certain nonattainment areas. 40 CFR 89 Control of Emissions from New and In- Use Nonroad Compression-Ignition Engines Contains exhaust emission standards (Tiers 1, 2, and 3) for compression-ignition (e.g., diesel) engines used in some non-road vehicles including airport GSE. 40 CFR 93 Subpart A Conformity to State or Federal Implementation Plans of Transportation Plans, Programs, and Projects Developed, Funded, or Approved under Title 23 U.S.C. or the Federal Transit Laws Transportation conformity may affect the operation of on-road airport GSE. 40 CFR 93 Subpart B Determining Conformity of General Federal Actions to State or Federal Implementation Plans General conformity may affect the operation of on-road and non-road airport GSE. 40 CFR 1039 Control of Emissions from New and In- Use Nonroad Compression-Ignition Engines Contains exhaust emission standards (Tier 4) for compression-ignition (e.g., diesel) engines used in some non-road vehicles including airport GSE. 40 CFR 1048 Control of Emissions from New, Large Nonroad Spark-Ignition Engines Contains exhaust emission standards for large spark-ignition (e.g., gasoline) engines used in some non-road vehicles including airport GSE. 40 CFR 1060 Control of Evaporative Emissions from New and In-Use Nonroad and Stationary Equipment Contains evaporative emission standards for non- road engines including those used in airport GSE. 40 CFR 1068 General Compliance Provisions for Engine Programs Contains basic compliance requirements for engines including those used in airport GSE. aCFR refers to the Code of Federal Regulations.

research Findings and products 15 of manufacture and rated engine output (e.g., horsepower) with greater stringency (i.e., lower emis- sions) associated with increasing emission control levels (i.e., Tier 0 < 1 < 2 < 3 < 4). These emis- sion standards and associated requirements are directed primarily at engine manufacturers, but the owners/operators also bear some responsibilities. For example, manufacturers of non-road CI engines must produce and offer for sale engines that meet the appropriate tier levels of emission standards and provide the necessary maintenance instructions and servicing procedures for the engine owner or operator to follow. Similarly, it is the responsibility of the owner/operator to follow the manufacturer’s main- tenance instructions thus enabling the engine to perform as designed and meet the applicable emission standards. These regulations also prohibit the disabling of emission controls on an engine or equipping an engine with an emission defeat device. It should be noted that, for non-road CI engines greater than 50 horsepower, the useful life is assumed to be 8,000 hours or 10 years, whichever comes first, and the warranty period is 3,000 hours or 5 years, whichever comes first. Owners and operators of CI non-road engines and equipment must also use ultra-low sulfur diesel fuel beginning in 2010. Spark-Ignition Engines The federal emission standards for SI non-road engines have been promulgated for equip- ment produced after 2004 and are also “tiered” to reflect increasing emission controls based on the date of manufacture and horsepower but include both exhaust emission standards and evaporative emission standards. Again, SI non-road engines are traditionally fueled with more volatile fuels, such as gasoline or natural gas, but alternatives to these fuels are emerging. As with CI engines, the emission standards and associated requirements are directed primar- ily at engine manufacturers, but the ultimate owner or operator does have some responsibilities related to emissions. Again manufacturers of SI non-road engines must produce and offer for sale engines that meet the appropriate level of emission standards, and provide the necessary maintenance and servicing procedures. Similarly, it is the responsibility of the owner/operator to follow the maintenance and service instructions. For large SI non-road engines, the useful life is assumed to be 5,000 hours or 7 years (except for severe-duty engines), whichever comes first, and the emission-related warranty period is 2,500 hours or 3 years for exhaust emission controls and at least 2 years for evaporative emis- sion controls. Fuel regulations require that in those parts of the United States with the worst air quality, SI engines must use reformulated or oxygenated gasoline to help reduce the formation of air pollutants. The U.S. EPA has also published voluntary emission standards for large SI non-road engines known as the “Blue Sky Series” for model years beginning in 2004. These standards, while they are voluntary, are intended to encourage manufacturers to develop innovative technologies to go beyond the required emission standards for these types of engines. Importantly, any manu- facturer certifying a class of its engines to the Blue Sky Series standards is required to ensure that the engines adhere to the standards as if they were mandatory. 3.2.3 On-Road Engine Emission Standards (Compression and Spark Ignition) According to the CAA, the term “motor vehicle” means any self-propelled vehicle designed for transporting persons or property on a street or highway. Thus, a motor vehicle, or on-road vehicle, may belong to any of a number of classes of vehicles, including light-duty vehicles (pri- marily automobiles and light-duty trucks), medium-duty trucks, heavy-duty trucks, buses, and

16 airport Ground Support equipment (GSe): emission reduction Strategies, Inventory, and tutorial other vehicles such as motorcycles. These types of vehicles may be fueled by a variety of types of fuels, including conventional petroleum-based fossil fuels such as gasoline and diesel, and cleaner-burning alternative non-petroleum-based fuels such as natural gas, propane, ethanol, methanol, biodiesel, hydrogen, electricity, and other fuels. Emission standards for on-road vehicles apply primarily to exhaust (i.e., tailpipe) emissions as well as evaporative emissions and are largely a function of the vehicle’s age (i.e., date of manufac- ture) as well as class of vehicle, type of fuel, and capacity and type of engine. As with non-road engines, engines used in on-road vehicles may be either compression ignition or spark ignition. Generally, the newer on-road vehicles have more restrictive emission standards than the older, preceding models. In nonattainment areas, owners or operators of centrally fueled fleets may be required to participate in the U.S. EPA’s clean fuel fleet program requiring the use of low-emission vehicles (40 CFR 88). Additional standards apply to fuels, fuel additives, and fueling, particularly, limita- tions on volatile components, sulfur, and certain toxic compounds such as benzene (40 CFR 80). In those nonattainment areas having a motor vehicle inspection/maintenance (I/M) program to reduce emissions, the vehicle owner/operator is responsible for meeting the state’s require- ments for periodic inspection and maintenance. Newer vehicles also utilize on-board diagnos- tics (OBDs) to assist the owner or operator to maintain the vehicle in proper service so that it will continue to meet applicable emission standards. The OBD system is designed to trigger a dashboard “check engine” light as a warning indicator to the driver of a possible malfunction of the engine’s emission control system. Each state’s I/M program includes an inspection of the OBD system. 3.2.4 Emission Standards in the State of California As noted in Section 3.2.1, California presents an exception to the federal preemption of state emission standards for mobile sources. For example, Section 209(e) of the CAA allows California to adopt and enforce standards and other requirements relating to the control of emissions from non-road engines or vehicles (other than construction or agricultural engines or vehicles smaller than 175 horsepower and locomotive engines). The only stipulation is that the California stan- dards must be at least as protective of public health and welfare as the applicable federal standards. Consequently, the California Air Resources Board (CARB) has adopted emission standards that apply to both CI and SI non-road engines and vehicles. Of particular importance to owners/ operators of GSE in California is the In-Use Offroad Diesel Vehicle Regulation (13 CCR Article 4.8 Sections 2449, 2449.1, 2449.2, and 2449.3) originally adopted in July 2007. In December 2010, CARB amended the regulation so that owners/operators of non-road CI vehicles greater than 25 horsepower (including GSE) are required to reduce emissions of diesel particulate matter and NOx. Importantly, these vehicles are subject to “fleet averaging” to meet the emission standards, which can be accomplished, if necessary, by engine retrofits or fleet turnover. The standard also requires enforcement of a 5-minute idling restriction as well as other requirements. The initial compliance date for the largest fleets is January 1, 2014, and smaller fleets would have later com- pliance dates. 3.2.5 State Implementation Plans and Emission Budgets As noted previously, under the federal CAA, each state is required to adopt a SIP that describes how it will implement, maintain, and enforce the NAAQS. In summary, the SIP must contain

research Findings and products 17 enforceable emission limitations and other control measures, means, and techniques as well as schedules and timetables to achieve compliance with the NAAQS. A SIP attainment or maintenance demonstration relies on detailed analyses of emission lev- els from stationary and mobile sources, including the degree of reductions of emissions (or reductions in the growth of emissions) and their impact on ambient air quality. From this, the SIP specifies projected future emissions (i.e., emissions budgets) that must be met to achieve the timely attainment and maintenance of the NAAQS. Afterward, the states conduct periodic inventories of emissions from applicable sources for comparison with the emissions budgets to ensure reasonable progress toward meeting the goals of the SIP. If reasonable progress is not being achieved, it may be necessary for a state to impose additional emission limitations or control measures. An up-to-date and accurate inventory of GSE and the associated emissions is but one com- ponent of the SIP emissions inventory. However, because GSE is not always accounted for or is otherwise misrepresented in SIPs, another ACRP research project is under way to improve this process (ACRP 02-21, “Evaluation of Airport Emissions within State Implementation Plans”). Although not directly applicable to emissions from individual on-road vehicles or fleets of vehicles such as GSE, the CAA Transportation Conformity Rule (40 CFR 93 Subpart A) requires metropolitan planning organizations (MPOs) to ensure transportation plans, transportation improvement programs, and transportation projects conform to the purpose of each state’s SIP. In this way, air quality conditions do not degrade due to contributions from an area’s transpor- tation system, including its on-road vehicles, and may include transportation control measures that impose operating conditions on the area’s highway and roadway system. Generally, non- road GSE engines and equipment are not addressed in an area’s transportation plan. Likewise, the CAA General Conformity Rule (40 CFR 93 Subpart B) requires any entity of the federal government (e.g., the FAA) that engages in, supports, or in any way provides financial support for, licenses or permits, or approves any activity (i.e., a “federal action” as defined in 40 CFR 93.152, unless otherwise determined to be exempt or presumed to conform) to dem- onstrate that the action conforms to the state’s SIP. With respect to GSE, the rule compels the airport operator or the project sponsor to account for the GSE emissions and either demonstrate that they are within acceptable thresholds (i.e., de minimis levels) or mitigate the increase in emissions, if necessary. 3.2.6 FAA’s Voluntary Airport Low Emission Program Under the Vision 100 Century of Aviation Reauthorization Act (signed into law in December 2003), the FAA administers the Voluntary Airport Low Emission (VALE) Program. The VALE Program is intended to offer financial and regulatory incentives to commercial service airports to voluntarily reduce emissions of air pollutants in geographical locations of the United States that are classified by the U.S. EPA as having nonattainment (or maintenance) status with respect to the NAAQS. While numerous types of airport projects are eligible for grants under the VALE Program, generally it focuses on alternative-fuel vehicles and low-emission technology infrastructure. The FAA annually issues updated technical guidance on the VALE Program, addressing eligibility of projects, funding sources, coordination with administering agencies, the process to apply for a VALE grant, and the responsibilities of an airport upon obtaining a grant under the program. The FAA has issued grants under the VALE Program since its inception in federal fiscal year 2005. Under the VALE Program, grant funds may be requested from either the Airport Improvement Program (AIP) or Passenger Facility Charges (PFC). Under the AIP, funding may come from

18 airport Ground Support equipment (GSe): emission reduction Strategies, Inventory, and tutorial either entitlements or from the discretionary “noise and air quality set-aside” budgets. For large or medium hub airports, VALE will reimburse 75 percent of the incremental cost of alternative-fuel vehicles and 75 percent of the total cost of eligible low-emission infrastructure (such as electric charging stations or compressed natural gas fueling stations). For smaller commercial service airports, the reimbursement values are consistent with AIP requirements. Airport matching funds may come from local revenues, state or local grants, or from PFCs. If PFCs are used for matching funds, they become subject to the AIP standard assurances and compliance requirements. To date, all VALE grants issued have been provided under the AIP. GSE acquired through the VALE Program can be owned by the airport and made available for use (e.g., leased) by another operator, such as an airline or fixed-base operator (FBO) that is a tenant at the airport. The VALE Program also permits an entity other than the airport, such as a tenant airline or FBO, to acquire and use alternative-fuel GSE, but that entity must commit to certain restrictions with regard to the use and disposition of the equipment, and it must honor all applicable AIP grant assurances. For VALE applications seeking AIP funding, the FAA recommends submitting an application in the spring of the prior federal fiscal year in anticipation of an award in the fall of the following federal fiscal year. An application seeking PFC funding may be submitted at any time. In the FAA Modernization and Reform Act of 2012 (signed into law by President Obama on February 14, 2012), a pilot program for zero-emission airport vehicles was authorized. The act provides some minimal guidelines for the U.S. Department of Transportation to follow if a program is established. However, the program details have not been developed at this time. 3.2.7 Other Grant Programs The National Clean Diesel Emissions Reduction Program, which is sometimes referred to as the Diesel Emissions Reduction Act (DERA), was created by the Energy Policy Act of 2005. Under this program, the U.S. EPA has provided funding assistance to support the deployment of U.S. EPA-verified and -certified technologies to reduce diesel-related emissions. The continued funding of DERA is presently pending. The related “SmartWay” Program allows the U.S. EPA to issue competitive grants to establish national low-cost revolving loans or other financing programs that provide funding for vehicle fleets to reduce diesel emissions. The availability of grant funds depends on annual appropria- tions and, at any given time, other funding opportunities applicable to GSE may be available from the various U.S. EPA regional offices. While an airport may seek FAA funding of emission reduction projects through traditional AIP entitlements, a candidate emission reduction project would have to compete against other capital improvement projects, requiring the airport to prioritize projects according to its needs and interests. The U.S. Department of Energy (DOE) may also provide opportunities for grants appli- cable to GSE, either through the Energy Efficiency and Renewable Energy (EERE) Program or through the Clean Cities Program. Because these funding mechanisms are constantly evolving, prospective applicants must check program guidance on a regular basis to determine specific opportunities. Some states provide opportunities for incentive grants and loans to implement emission reduction projects. Examples include the Carl Moyer Program at the California Air Resources Board and the Emission Reduction Incentive Grant Program at the Texas Council on Envi- ronmental Quality. Prospective applicants should check with their state’s air quality regulatory agency on the availability of such programs and the associated eligibility requirements.

research Findings and products 19 3.3 Air Emission Mitigation Strategies Applicable to GSE This section identifies and discusses various approaches that have been implemented at air- ports to reduce air emissions from GSE. In addition, the available incentives, the benefits gained, and the potential barriers to attaining emission reductions associated with GSE are also dis- cussed. For ease of comprehension, the prevailing approaches are described first followed by specific airport examples of GSE emission reduction measures. 3.3.1 Equipment-Related Approaches Equipment-related approaches to reducing emissions from GSE characteristically comprise (1) the use of infrastructure or hardware systems as an alternative to GSE, (2) the use of add- on control devices on conventional-fuel GSE, and (3) the use of the advanced fuel combustion technologies for conventional-fuel GSE. Infrastructure and Hardware Systems In some cases, the primary functions of select types of GSE can be replaced by incorporating fixed point-of-use support equipment into airport terminal gate design. One common example involves terminal gate electrification through the use of (1) fixed preconditioned air (PCA) sys- tems replacing diesel-powered air conditioning units (ACUs) and (2) 400 Hz electrical systems to replace diesel-powered ground power units (GPUs) and aircraft air start units (ASUs). Although many aircraft use on-board jet fuel-powered auxiliary power units (APUs) to perform these nec- essary functions, the PCA and 400 Hz systems eliminate the need for such GSE and minimize APU use. Notably, APU usage at the gate cannot be eliminated completely as it is required during preflight checks and aircraft main engine startup. As discussed in Section 3.2, eligible airports can obtain funding under the FAA VALE Program for these qualified infrastructure projects that reduce air emissions. For example, the Seattle- Tacoma International Airport (SEA) recently obtained VALE funding for the installation of PCA at 82 gates and the Gerald R. Ford International Airport (GRR) obtained VALE funding for PCA and 400 Hz power at five gates. Another infrastructure GSE emission reduction example is the use of in-ground hydrant fuel- ing systems in place of mobile refuelers thereby decreasing engine emissions associated with these trucks. Most fuel hydrant systems still require an interface between the in-ground system and the aircraft, commonly provided by an engineless fuel cart or a fuel pumping truck powered by a conventional-fuel engine. Importantly, such infrastructure projects are less costly to install when designed as part of new facilities rather than as retrofits to existing facilities. For example, a gate electrification project may require an upgrade to the power supply to the terminal building, electrical improvements at the terminal gate, and power improvements within the gate area. Installing a fuel hydrant system at existing airport facilities can also be relatively expensive as well as disruptive of operations in the terminal gate area because it requires belowground installation. Installing more advanced systems to replace GSE (e.g., a centralized conveyer belt-driven bag- gage distribution and delivery system to replace baggage tugs and belt loaders) are also possible. However, the costs and cost effectiveness for these types of infrastructure improvements are dif- ficult to generalize and would need to be evaluated on a case-by-case basis. Add-on Emission Control Devices Engine exhaust after-treatment systems have been successfully used in on-road vehicles for more than 35 years to reduce emissions. In general, these control devices serve to collect and convert the exhaust emissions to more environmentally friendly compounds before they are

20 airport Ground Support equipment (GSe): emission reduction Strategies, Inventory, and tutorial discharged into the atmosphere. The following examples of exhaust after-treatments are appli- cable to GSE: • Oxidation catalysts: At the most basic level, oxidation catalysts use a material such as plati- num to more efficiently oxidize unburned hydrocarbons and CO in the engine exhaust to carbon dioxide (CO2) and water. • Three-way catalytic converters: These devices oxidize unburned hydrocarbons and CO to CO2 and water, but also reduce NOx to molecular nitrogen and oxygen. These devices have been particularly successfully in on-road vehicles in the form of catalytic converters but are currently only compatible with spark-ignition engines. The removal of lead and the lowering of the sulfur content in gasoline have further improved the effectiveness of these devices. • Particulate traps: Particulate traps collect soluble and carbonaceous particulate matter in the diesel exhaust and during regeneration convert it to CO2 and water. Because sulfur in fuel can inter fere with the operation of the device, the technology requires the use of ultra-low sulfur diesel. GSE equipped with non-road engines are characteristically “open-loop” systems that have no combustion control feedback system to adjust the air/fuel mixture. For this reason, only the oxida- tion catalyst technology is used on these engines (both compression ignition and spark ignition). In those applications where the non-road engines have been retrofitted with a “closed-loop” combustion control system, then the three-way catalytic converter can be used effectively to reduce emissions but limit the maximum power available for the GSE. Furthermore, because some types of GSE engines are tuned to run rich, adjusting the air/fuel ratio to run lean would limit the engine power available to the equipment. Because these types of add-on control devices need to reach a critical temperature to allow the conversion of pollutants to take place, GSE with short duty cycles (i.e., low load factors) may not achieve the temperatures needed for maximum conversion efficiency. For particulate traps, backpressure increases as particulate matter collects on the trap. If the operating cycle of the GSE does not include sufficient periods of high load (which promotes the necessary regeneration temperature), it can affect the performance of the equipment. The ideal condition is a high-load activity level to regenerate the trap regularly and maintain low backpressure on the trap. One other potential constraint of note is the space requirement for the add-on devices. Since such equipment has to be retrofitted onto GSE not originally designed to accommodate it, one must consider how the placement of the add-on device can be accomplished without interfering with the intended operation and maintenance of the GSE. Evolving Engine Technology for Conventional Fuels In the mid-1990s, the U.S. EPA began to issue non-road engine emission standards that are being phased in over a number of years; prior to these standards, non-road engines were essen- tially non-regulated. In particular, initial standards for non-road compression-ignition (e.g., diesel) engines were promulgated in 1996 and then more advanced standards were set in 2008. For non-road spark-ignition (e.g., gasoline) engines, the U.S. EPA promulgated standards to take effect over the period from 2004 through 2008. These standards will result in significant emis- sion reductions (in some cases, greater than 90 percent) from the non-regulated baseline as the cleaner engines meeting the emission standards displace the uncontrolled equipment. 3.3.2 Alternative-Fuel GSE Fuel-related solutions to reduce emissions from GSE include the use of alternative-fuel and electric-power GSE in place of conventional-fuel GSE, either through acquisition of new

research Findings and products 21 purpose-built equipment or retrofitting of existing equipment. Today, a variety of alternative combustion fuels are available for use in internal combustion engines that power GSE. The primary alternative fuels known to be used in GSE include compressed natural gas (CNG), liquefied petroleum gas (LPG, also known as propane), ethanol, and biodiesel. These fuels typically generate lower air emissions than the conventional fuels; however, the relative energy content and on-airport infrastructure requirements to provide alternative fuel may reduce the overall air quality benefit associated with the use of this equipment. In addition, accounting for off-airport electric power generation impacts associated with charging electric GSE also reduces the air quality benefits of this equipment. The detailed discussion of benefits and challenges of alternative-fuel GSE are presented in Section 3.4 (Economic and Environmental Challenges and Considerations with Alternative-Fuel GSE). 3.3.3 Operations/Maintenance-Related Approaches Operators of GSE have developed specific operations and maintenance (O&M) programs for the GSE that they own. These procedures have been developed to reduce the overall cost of run- ning GSE as well as to avoid operating delays associated with equipment breakdowns. However, there are potential air quality benefits to these O&M measures too, for example, (1) idling time restrictions and (2) maintenance activities. Idling Time Restrictions Above and Beyond Regulatory Requirements Most GSE duty cycles consist of short periods of high-load operation followed by extended periods of idle or engine off. Over a long period of operation, the engine load factor (ratio of actual work performed to the maximum work that the engine is designed to do) can account for differing operating conditions and must be taken into account when estimating emis- sions. Although load factors for GSE have been developed, they may be highly uncertain on a generalized basis when attempting to account for differences across multiple units of the same type, across airlines, and across airports. Equipment idle time can vary considerably and, in extreme cases where idle periods represent the major portion of the duty cycle, the load factor approaches zero while the actual emission rate per unit work performed approaches infinity. Idling of GSE is a common practice, particularly for diesel equipment, primarily as a conve- nience to the operator to maintain the equipment in a ready mode and avoid lengthy warm-up periods in cold climates. However, an engine at idle continues to emit pollutants, although at a different rate from that under higher load conditions. Imposing idling restrictions on GSE (e.g., no idling longer than five minutes) could result in substantial emission reductions in the long term. Implementing such restrictions may be as simple as training operators to turn off the engine after use. Alternatively, an anti-idling device could be installed that automatically shuts off the engine after a pre-set period of time. For engines that need to be maintained in a “warm standby” condition for ready access or in the case where an equipment cab needs its interior temperature maintained for operator comfort, a small auxiliary unit can be integrated with the anti-idling device to keep the equipment in a ready condition while reducing overall emissions. Including the small auxiliary unit into such a system design would clearly limit the degree of emission reductions achieved in practice. Maintenance Activities In general, maintenance activities have been developed to cost effectively limit equipment downtime in maintenance while avoiding inconvenient equipment breakdowns during opera- tions. As part of the field surveys, maintenance activities that have potential air emissions were noted along with any available mitigation options.

22 airport Ground Support equipment (GSe): emission reduction Strategies, Inventory, and tutorial 3.3.4 Other Approaches At least two other approaches to managing GSE emissions also exist: emission-related fees and tenant lease agreements. Emissions Fees While no data were obtained indicating that GSE are being assessed emission fees at airports in the United States, several European airports assess fees on aircraft emissions. Tenant Lease Agreements Several airports have begun attempting to incorporate emission reduction goals into tenant lease agreements. However, the use of such goals in lease agreements can be problematic and may not be a viable option because the goals may not be legally binding on an airline. There are numerous constraints on U.S. airport proprietors that would limit their ability to reduce emissions associated with airport operations. These constraints include federal laws preempting certain actions by airport proprietors to regulate air carriers, the ban on passenger head taxes, the prohibition against diverting airport revenue for non-airport purposes, and the requirement to impose only reasonable and not unjustly discriminatory terms and conditions on aeronautical users. (Reimer and Putnam, 2007) 3.3.5 Airport-Specific GSE Emission Reduction Measures Presently, there are a great number and variety of GSE emission reduction measures in place (or planned) at airports of nearly every size and function located across the United States and internationally. The sponsors of these initiatives also range widely and include airlines, airport operators, and GSE providers. Table 3-5 provides a partial sampling of these GSE emission reduction measures implemented over the past few years. For the purposes of this research project, this listing is not intended to be inclusive but rather to provide some examples of these programs. The GSE tutorial includes a more comprehensive and up-to-date compilation of these measures and programs. This information pertains only to airside GSE and does not include the large number and wide array of other emission reduction and alternative-fuel programs at these airports. 3.4 Economic and Environmental Challenges and Considerations with Alternative-Fuel GSE Prepared in support of Task 3, this section reports on the primary economic and environmen- tal considerations and challenges associated with owning and operating GSE. Because this topic is multifaceted and comprehensive, the economic elements are discussed first and the discussion of the environmental factors follows. 3.4.1 Economic Considerations and Challenges Compared to using traditional petroleum-based gasoline and diesel fuels, using alternative fuels (i.e., substitutes for traditional liquid, oil-derived motor vehicle fuels) in airport GSE may reduce energy costs, maintenance costs, and dependence on fossil fuels. The following material compares the costs of fueling GSE with conventional, petroleum-based fuels versus alternative fuels. In addition to fuel costs, characteristics such as performance, energy content, cold weather limitations, maintenance costs, and funding opportunities are also presented.

research Findings and products 23 Implementer GSE Program Details Example Airport Programs Atlanta Hartsfield-Jackson International Airport (ATL) At ATL, a new baggage system, extensive use of fueling carts in lieu of fueling trucks, and more than 200 new electric GSE units are expected to result in reductions in conventional fuel use and emissions associated with GSE. Virtually all of ATL’s gates are equipped with preconditioned air and 400 Hz power, which greatly reduces the emissions that result from APU usage at the airport’s gates (See also Delta Air Lines). Boston Logan International Airport (BOS) Delta Air Lines received a $3 million loan from Massport in 2009 for the purchase of 50 electric baggage cart tugs, 25 electric baggage conveyor belt vehicles, and charging stations as part of the replacement of Terminal A. Massport has a number of other GSE emission reduction programs under way at BOS. Charlotte Douglas International Airport (CLT) CLT introduced 10 battery-powered tugs on the Express ramps to replace their old diesel-engine counterparts, reducing N2O emissions by as much as 70 tons. Dallas-Fort Worth International Airport (DFW) DFW selected Clean Energy Fuels in 2010 to construct and operate a new CNG refueling station at this airport. Most of the airport’s fleet of more than 500 maintenance vehicles operates using CNG. The fleet is also fueled at another on-site CNG refueling station constructed in 2000. Denver International Airport (DIA) The Alternative-Fuel Vehicles (AFV) program was implemented with the construction of DIA. The GSE fleet at the airport includes 40 CNG bag tugs, nine electric bag loaders, and four electric cargo tractors. The CNG fleet at DIA is one of the largest in the country. The underground tunnel system connecting the terminal and concourses allows only CNG and electric vehicles. CNG pumping stations are available on site. Detroit Metropolitan Wayne County Airport (DTW) In 2007, DTW received a $1.4 million VALE grant for gate power and preconditioned air for 26 gates at the new North Terminal. George Bush Intercontinental Airport (Houston) (IAH) In 2008, IAH was awarded a $25,000 VALE grant for two new electric GSE units. This is only one of several GSE emission reduction programs undertaken by the Houston Airport System (HAS) and airlines that utilize the HAS airports. Indianapolis International Airport (IND) In 2008, Aircraft Service International Group (ASIG) purchased seven solar-powered hydrant carts for use at IND. (Notably, ASIG also operates these same carts at Seattle-Tacoma International Airport and Fort Lauderdale International Airport.) John Wayne Airport (SNA) In 2009, SNA’s Airport Terminal Services added eTug electric tow tractors to its fleet and an eCart battery baggage cart. The eCart enables the eTug to operate 24 hours/day without the need for a stationary charge period. ETug also operates on its own set of batteries. This potentially reduces the number of tractors required because none have to be down for any period to charge. Lambert-St. Louis International Airport (STL) STL has approximately 400 vehicles and other GSE operating on biodiesel fuel including trucks, sweepers, plows, loaders, aircraft rescue and firefighting (ARFF) vehicles, and emergency generators. Currently STL is converting its remaining gasoline vehicles to CNG and its on-site CNG fueling station serves 60 airport maintenance vehicles. Lehigh Valley International Airport (ABE) In 2010, ABE received a $700,000 VALE grant for the purchase of eight preconditioned air units and eight electric GSE, the installation of three electric GSE rechargers, and the purchase of six new hybrid vehicles to replace older, conventional-fuel vehicles. The project is expected to save over 65,000 gallons of fuel and at an initially estimated cost savings of approximately $165,000 annually. Los Angeles International Airport (LAX) In 2011, eight airlines at LAX signed a joint agreement for the purchase and use of renewable synthetic diesel fuel for their GSE at this airport. The signees include ASIG (purchasing the fuel, transportation and dispensation of synthetic diesel), Rentech, Inc. (producer of RenDiesel fuel using a biomass gasification process at a facility in Rialto, CA), Alaska Airlines, American Airlines, Continental Airlines, Delta Air Lines, Southwest Airlines, United Airlines, United Parcel Service (UPS), and US Airways. In 2010, Los Angeles World Airports also drafted a GSE conversion policy requiring that all GSE be converted to zero-emission equipment by 2015. (continued on next page) Table 3-5. Sampling of GSE emission reduction measures implemented by airports.

24 airport Ground Support equipment (GSe): emission reduction Strategies, Inventory, and tutorial Implementer GSE Program Details Louisville International Airport (SDF) In 2009, the airport’s largest tenant United Parcel Service (UPS) was selected by the U.S. EPA to receive a $500,000 award to reduce diesel PM. The grant funds the replacement of 92 GSE cargo tugs and the extension of ground power electricity to parked aircraft, replacing 26 mobile diesel ground power units. New York LaGuardia Airport (LGA) At LGA, in 2006 Delta Air Lines replaced diesel GSE with fast-charging electric GSE, reducing emissions by 19.2 tons per year. Norman Y. Mineta San Jose International Airport (SJC) In 2009, SJC was awarded a $4.6 million VALE grant to install preconditioned air and electrical power upgrades at 13 gates in Terminal A, reducing diesel GSE use and aircraft engine operations. Oakland International Airport (OAK) As part of the Terminal 2 extension project at OAK, electric power for GSE was installed at each of the seven new gates. Southwest Airlines will begin using electric baggage loaders and is installing rapid battery chargers. Philadelphia International Airport (PHL) In 2009, PHL was awarded a $3 million VALE grant for the installation of preconditioned air at 24 gates, and 25 rechargers to support 184 electric GSE vehicles purchased by US Airways. The preconditioned air units at the US Airways gates are expected to reduce NOx emissions by 414.7 tons over the next 26 years. The 184 electric GSE vehicles will replace diesel GSE vehicles and are expected to reduce NOx by 191.9 tons over the next 13 years. Of note, this is only one of several VALE grants awarded at PHL over the past few years that were applied to the reduction of GSE emissions. Phoenix Sky Harbor Airport (PHX) As part of the City of Phoenix’s alternative/clean fuel program, approximately 250 operational vehicles at PHX (including GSE) use low- sulfur fuel or other alternative fuels (i.e., CNG or biodiesel) or are hybrid vehicles. Portland International Airport (PDX) Since 1997, PDX has been replacing airport vehicles fueled by gasoline and diesel with vehicles fueled by CNG. PDX has 46 dedicated CNG vehicles including trucks and forklifts used as GSE. PDX also has several propane forklifts and a scrubber/sweeper as well as a fleet of 27 biodiesel pieces of off-road equipment. Sacramento International Airport (SMF) SMF instituted a program to deploy 54 alternative-fuel vehicles including 20 belt loaders converted from gasoline to electric power. The program saved the airlines that owned the vehicles $10,000 per vehicle. Salt Lake City International Airport (SLC) SLC has instituted a clean-fuel program composed of CNG, electric, biodiesel, and hybrid vehicles; CNG refueling stations; and economic incentives for tenants to convert to these technologies. San Francisco International Airport (SFO) The airport used an Inherently Low-Emission Airport Vehicle Program grant to purchase alternative-fuel vehicles and infrastructure including 54 electric vehicles such as bag tugs, belt loaders, and pushback tractors. The program also included the gasoline-to-propane conversion of 83 vehicles and the purchase of recharging systems for electric vehicles. Seattle-Tacoma International Airport (SEA) In 2010, SEA obtained $5 million from the Puget Sound Clean Cities Coalition to subsidize the purchase of 200 electric GSE vehicles and charging stations. The electric GSE will include bag tugs, belt loaders, and pushback tractors owned and operated by tenant airlines. The project initiates SEA’s efforts to be the first airport in the United States to fully electrify its GSE fleet. SEA is also developing a plan to own the GSE and lease it for use to a consortium of airlines, thereby allowing for a more centralized approach to recharging. For APUs, SEA is anticipating a $22 million VALE grant for installing preconditioned air at each terminal area gate. Westchester County Airport (HPN) HPN was awarded a $1 million VALE grant for the replacement of gasoline and diesel GSE and the purchase of 25 electric GSE vehicles and 13 mini-chargers. The new GSE includes baggage and aircraft tractors, water trucks, and baggage belt loaders, reducing emissions by 330 tons per year and saving an estimated $240,000 annually in fuel costs. Example Airline Programs Alaska Airlines Alaska Airlines has converted or replaced a portion of its gas-powered fleet with cleaner-burning propane units or hybrid GSE. Approximately 10 percent of the GSE fleet has been converted to electric. American Airlines Since 2000, American has converted approximately 30 percent of its GSE bag tractors and belt loaders from gasoline and diesel to electric. American has also installed fast electric chargers at DFW, New York JFK, Chicago O’Hare (ORD), and LAX for its GSE. Table 3-5. (Continued).

research Findings and products 25 Implementer GSE Program Details Continental Airlines Continental reports that NOx emissions from GSE have been reduced by approximately 75 percent at IAH by switching to electric GSE and other emission reduction technologies. Delta Air Lines In 2010, Delta opened its new GSE facility at ATL where it conducts the majority of the GSE fuel conversions. Delta has also announced plans to purchase approximately 600 new GSE units valued at $50 million including approximately 100 electric GSE units for airports that have the infrastructure to support electric. Horizon Air As of January 1, 2010, over 65 percent of the GSE fleet is electric. Southwest Airlines As of March 2012, Southwest has purchased or converted more than 850 GSE units to electric including baggage tugs, belt loaders, lavatory trucks, carts, and pushback tractors. In doing so, the carrier reduced its GSE fuel consumption by approximately 700,000 gallons annually. Additionally, Southwest has converted to gate service electricity in 61 of the 64 airports it serves, reducing APU fuel consumption by more than 15 million gallons in 2007. US Airways As of the end of 2010, more than 20 percent of the US Airways GSE fleet was electric, including 38 electric tugs recently added in Philadelphia in conjunction with the Philadelphia Division of Aviation. US Airways has also committed to purchase 1.5 million gallons per year of synthetic diesel fuel for use in GSE at LAX. United Airlines United Airlines operates about 325 electric vehicles at DIA ranging from baggage tractors and forklifts to golf carts and also operates approximately 200 natural gas vehicles including tugs, vans, and light-duty pickup trucks. United Parcel Service At the UPS WorldPort facility at SDF, electric loaders have been installed at each loading dock along with 400 Hz GPUs. UPS has also re-powered 92 tugs with cleaner gasoline engines through an EPA grant. At LAX, UPS is also re-powering more than 100 tugs to use newer low-emission engines. UPS is one of eight airlines at LAX that signed an agreement for the use of synthetic renewable diesel fuel beginning in 2012. UPS has more than 2,200 tugs throughout the world and plans to re-power all of them. Example GSE Provider Programs Aviapartner Based in Brussels, Aviapartner operates 31 GSE units throughout Europe and is using a new “Visualizer” airport system in order to facilitate more efficient use of its vehicles, thereby reducing fuel use and emissions. It is also assessing the concept of “pooling” GSE for common use among airlines. Elite Line Services Elite Line Services has converted all of Alaska Airlines’ cargo operation to electric forklifts and fast charge. In addition, it is in the middle of a project to upgrade all the Anchorage International Airport (ANC) cargo forklift fleet to electric. FRAPORT The operator of the Frankfurt Airport is conducting trials on hydrogen- powered GSE as well as conducting GSE use studies to improve the efficiency of GSE utilization with the objective of reducing fuel use and emissions. Menzies Aviation Menzies Aviation has implemented electric baggage tugs at its locations and recently added 11 eTugs to its GSE fleet. As of May 2009, 30 tugs out of 110 in its fleet were electric. Rentech Inc. Rentech has entered into agreements with several airlines in the Los Angeles Basin to use its alternative fuel in GSE. Major airline partners include American, Southwest, Delta, United, and Continental. SwissPort A leading international ground services and cargo handling provider, SwissPort follows a strict renewal and replacement strategy for its GSE all over the world. Electric bag and cargo tractors are employed in many locations and, where not, they will be introduced over the next few years. SwissPort also works closely with major GSE manufacturers in developing modern vehicles with low fuel consumption and low emissions. All its diesel vehicles have been outfitted with filters for soot particles. Table 3-5. (Continued).

26 airport Ground Support equipment (GSe): emission reduction Strategies, Inventory, and tutorial Types of Alternative Fuel The Energy Policy Act of 1992 (EPAct) defines an alternative fuel as a fuel that is substantially non-petroleum and yields energy security and environmental benefits. Congress passed the EPAct to reduce U.S. reliance on foreign oil by providing tax breaks and requirements for the use of alternative fuels (Sections 501 and 507) to fuel federal fleets. The EPAct considers the following fuels to be alternative options to conventional gasoline or diesel fuel: • Mixtures containing 85 percent or greater ethanol (E85) • Mixtures containing 20 percent or greater biodiesel meeting ASTM D 6751 • Natural gas (compressed or liquefied) • Liquefied petroleum gas (propane) • Methanol • Hydrogen • Electricity To focus the evaluation of transitioning from GSE using traditional petroleum-based gasoline or diesel fuels to GSE using alternative fuels, the following paragraphs describe each alternative fuel previously listed, with the exception of methanol. However, not all the alternative fuels listed under the EPAct of 1992 are available for wide- spread use in GSE. Availability, especially for biofuels and hydrogen, is particularly limited based on airport location. Moreover, methanol is not often used in the aviation industry because of its lack of widespread availability. Other limiting characteristics of methanol include its corrosive nature, low energy density (about 50 percent less than gasoline), and poor performance below 45 degrees Fahrenheit. Therefore, although methanol may be used as a component to produce biofuels and has chemical and physical characteristics similar to ethanol, it is not discussed further. Ethanol. Ethyl alcohol, or ethanol, is a clear, colorless liquid made from fermenting a bio- mass in carbohydrates. Starch- or sugar-based ethanol sources include corn grain and sugar cane; cellulose-based sources include grass, wood, and crop residues. Low-level blends of ethanol and gasoline (less than 10 percent ethanol) can be used in any gasoline-powered engine without modification, although blends of less than 85 percent ethanol and 15 percent gasoline (E85) do not qualify as an alternative fuel under the 1992 EPAct. Typi- cally, E85 is priced lower than gasoline on a gallon-for-gallon basis but more than gasoline on an energy-equivalency basis. Blends containing more than 10 percent ethanol are only approved for use in flexible fuel vehicles (FFVs), which are capable of running on both E85 and gasoline. The characteristics of ethanol follow: • Availability. There are about 200 ethanol production plants located in the United States, pri- marily in the Midwest. As of August 2010, approximately 8 million FFVs were on U.S. roads (although only a portion of these vehicles actually use ethanol); there were 53 different 2011 FFV models from domestic and foreign automakers. • Energy balance and high octane. Despite some misconceptions, the total amount of energy used to produce ethanol (i.e., by farming, shipping, and production equipment) is less than the energy released when it is burned (known as the energy balance). The energy balance for corn-based ethanol is approximately 1.24 (for 1 unit of energy produced, 1.24 units of energy are released) and it is expected to increase as technology advances. As a high-octane fuel, ethanol increases horsepower, helps prevent pre-ignition or engine knocking, and enables engines to operate at a higher compression ratio. In the United States, ethanol is often added to gasoline in a low-level blend to oxygenate the fuel and reduce air pollution emissions.

research Findings and products 27 • Cold temperature fuel gelling. Because E85 may freeze in lower temperatures, fueling sta- tions may need to switch to a lower blend of ethanol during winter months to prevent starting problems. All FFVs can transition to E70 or other lower-level blends without any adjustments. • Energy efficiency. Ethanol produces less energy per gallon than gasoline, depending on the blending ratio. As the ratio of ethanol to gasoline increases, the fuel economy decreases. E85 generates 15 to 30 percent lower gas mileage because E85 has approximately 27 to 36 percent less energy content per gallon than gasoline. • Engine modifications. Ethanol is a strong cleaning agent and has the ability to degrade engine parts manufactured from materials such as natural rubber, plastics, and even metals over time. Therefore, E85 should not be used in existing gasoline or diesel engines without performing modifications. Many existing petroleum-based gasoline-powered vehicles can be converted to use E85 through kits approved by the U.S. EPA. A typical conversion kit mounts in a vehicle’s engine compartment and continuously monitors engine and emission controls. The kit sup- plies supplementary fuel injection to allow for the same ethanol/gasoline compatibility as a FFV. Conversion kit costs vary by the engine type and vehicle model. • Storage. Ethanol has a shelf life of about 3 months although it can last for several years if it is properly sealed. The ethanol content in E10 can absorb more water than gasoline, and when the water evaporates valuable fuel components are lost, reducing the efficiency of the fuel. A vehicle’s fuel should be used or replaced within 2 to 3 weeks, or even sooner in humid conditions. Biodiesel. Biodiesel is produced by vegetable oil, animal fat, or cooking grease reacting with alcohol (typically methanol) in the presence of a catalyst. In the United States, common sources for biodiesel production are soybean oil and recycled cooking oil. B100 consists of 100 percent pure or “neat” biodiesel and contains no petroleum-based diesel. A blend must be at least 20 per- cent biodiesel and 80 percent petroleum diesel (B20) to be considered an alternative fuel under the EPAct. To be considered fuel-grade biodiesel, B20 must satisfy the performance requirements and the defined physical and chemical properties of the American Society for Testing and Materials (ASTM) outlined in Specification D 7467. B20 meets the EPAct requirements, minimizes the limitations of high-level blends, and is the most common blend in the U.S.; therefore, this section primarily focuses on the key considerations of B20. The characteristics of biodiesel follow: • Availability. A total of 613 biodiesel fueling stations (288 public and 325 private of various blends) were located in the United States as of January 2011. The U.S. DOE estimates that the United States has enough soy oil, feedstock, and recycled restaurant grease to provide 1.7 billion gallons of biodiesel per year (approximately 5 percent of on-road diesel use). • Cold temperature fuel gelling. Low-temperature gelling of biodiesel clogs fuel filters and makes the fuel unusable. B20 may begin to gel when the temperature reaches approximately 8 degrees Fahrenheit, depending on the feedstock used to produce it. For example, biodiesel produced from canola, safflower, and sunflower oils are less likely to gel in cold temperatures while coconut and palm oils (high in saturated fat) are more likely to freeze. Therefore, operators should know what feedstock was used to produce the biodiesel prior to use in cold weather. The National Renewable Energy Laboratory and the U.S. DOE do not recommend the use of high-level blends such as B100 due to concerns about cold temperature gelling (at around 32 degrees Fahrenheit), material compatibility, maintenance requirements, and solvency properties. Appling additives to the fuel such as kerosene, using filter and block heaters, and/or storing vehicles indoors may help reduce the likelihood of cold temperature gelling.

28 airport Ground Support equipment (GSe): emission reduction Strategies, Inventory, and tutorial • Energy content. Similar to ethanol, as the proportion of biodiesel to petroleum-based diesel fuel increases, the energy content decreases. Biodiesel (B100) has a 7 to 9 percent lower energy content than petroleum-based diesel fuel, which reduces an engine’s fuel economy, peak horse- power, and peak torque. These changes, especially in blends greater than B20, may offset fuel cost savings. • Maintenance. Switching from petroleum-based diesel to biodiesel may clog fuel filters because of biodiesel’s solvency characteristics. Existing sediment from petroleum-based diesel could be dislodged with the start of biodiesel use (especially higher blends), reducing fuel flow to the engine and causing a stall. If the sediment causes the filter to rupture, sediment could travel into the fuel lines, pump, and injectors, resulting in expensive repairs. Therefore, during the initial transition from petroleum-based diesel to biodiesel (especially blends of B20 or higher), routine maintenance should be performed to check for and replace clogged fuel filters. Biodiesel blends higher than B20 have a higher viscosity and density than petroleum- based diesel, which may cause unburned fuel to bypass the piston rings and drain into the oil pan. This may cause the accumulation of engine sludge, shortening the engine’s lifespan and requiring more frequent engine oil and filter changes. • Shelf life. Compared to petroleum-based diesel, stored biodiesel is more likely to react with oxygen and form a gel-like substance; this is a concern when using GSE that is only operated occasionally or when storing GSE for more than 6 months after the manufacture date. The higher the concentration of biodiesel in the blend, the faster it is likely to degrade. Using storage-enhancing additives and/or a dry, semi-sealed, cool container can also alleviate stor- age concerns. Biodiesel is an active growing environment for microorganisms because it is a greater attractant of water than petroleum-based diesel. If biodiesel is stored for long periods of time, the denser water will collect at the bottom of the fuel tank and promote microbial growth that may cause engine failure, fuel filter clogging, and corrosion. • Solvency. Because biodiesel is a natural solvent, high concentrations of biodiesel will soften and degrade rubber compounds that may be located in fuel hoses, gaskets, and fuel pump seals. B20 can be used in most diesel vehicles and fuel-injection equipment manufactured after 1993 without having an impact on operating performance or requiring engine modifications. The U.S. DOE has not received any reported rubber compound problems due to B20 (i.e., ruptured fuel hoses or fuel pumps) since 2006, even with older engines. However, a thorough search for incompatible rubber compounds in the fueling system should be performed prior to fueling GSE with biodiesel. Compressed Natural Gas. Commonly used to heat stoves and houses, CNG is pressurized natural gas that remains colorless, odorless, and noncorrosive. CNG primarily consists of meth- ane drawn from gas wells, oil wells, and coal bed methane wells, although it may also consist of synthetic gas, landfill gas, and coal-derived gas in smaller quantities. Although vehicles can use natural gas as either a liquid or a gas, most vehicles use the gaseous form compressed in high- pressure fuel cylinders at 3,000 to 3,600 pounds per square inch. The characteristics of CNG are as follows: • Availability. CNG is typically imported through pipelines although it may also be transported as a cryogenic (super-cold) liquid. An extensive network of natural gas pipelines is presently located across the United States, connecting wellheads and electrical generation plants to resi- dential, commercial, and industrial buildings for heating and cooling. Natural gas accounts for about one-fourth of the energy used in the United States, although only one-tenth of 1 percent is currently used for transportation fuel. • Performance and operating costs. No noticeable difference in horsepower, acceleration, and cruise speed exists between a CNG vehicle and a similarly sized gasoline or diesel vehicle. The

research Findings and products 29 cost of CNG is typically 15 to 40 percent less than gasoline or diesel and the CNG market has historically been more stable. • Maintenance. Oil changes in a CNG vehicle are less frequent compared to a gasoline or diesel vehicle, because CNG burns cleaner, producing fewer oil deposits. • Storage requirements. CNG only contains about a quarter of the energy by volume of gaso- line. Therefore, the driving range of a CNG vehicle is less than that of comparable gasoline and diesel vehicles, requiring more frequent fueling. Larger storage tanks can be installed to increase range, but the additional weight displaces payload capacity. Furthermore, the higher cost of the fuel cylinders and CNG tanks means that CNG vehicles cost from $3,500 to $6,000 more than their gasoline-powered counterparts. Operating temperature during refueling must be kept below negative 40 degrees Fahrenheit to reduce liner stress. To reduce risk, all CNG tanks should have a residual pressure control system. Propane or Liquefied Petroleum Gas. LPG is a naturally forming gas composed of both petroleum and natural gas. LPG comes from either petroleum refining (45 percent of LPG used in the United States) or natural gas processing (55 percent). Because of its versatility and effi- ciency, LPG is commonly used for heating and cooking in rural areas of the United States that are not connected to natural gas pipelines. LPG vehicles operate similarly to gasoline vehicles with SI engines. LPG changes to a liquid state in an LPG vehicle’s fuel tank, where it is stored at a pressure of about 300 pounds per square inch. Today, most propane vehicles are conversions from gasoline vehicles. The characteristics of LPG are as follows: • Availability. Propane has been used as a commercial motor fuel for over 80 years. As of 2011, there are more than 270,000 on-road LPG vehicles in the United States and more than 10 mil- lion worldwide. Many are used in fleets, including light- and heavy-duty trucks, buses, taxicabs, police cars, and rental and delivery vehicles. • Maintenance. LPG has an octane rating from 104 to 112 compared with 87 to 92 for con- ventional gasoline fuel. The higher octane rating increases power output and fuel efficiency while preventing engine knocking. Propane’s low carbon and oil contamination characteris- tics have resulted in documented engine life of up to two times that of gasoline engines. No cold temperature problems are associated with LPG since the fuel mixture (propane and air) is completely gaseous. Propane operating costs for fleet vehicles range from 5 to 30 percent less than that for conventional or reformulated gasoline vehicles. • Performance. Since LPG is less dense than gasoline, power may decrease, but operators rarely notice this loss. LPG fleet operators have reported that horsepower and torque capabilities, as well as vehicle cruising speed, are roughly comparable to those for gasoline vehicles. Fuel economy on new engines is also comparable to that of gasoline engines. • Refueling. LPG vehicles have a refueling rate of approximately 10 to 12 gallons per minute, which is comparable to that of gasoline; and presently approximately 10,000 refueling stations are located across the country. • Dedicated LPG vehicles. The availability of dedicated LPG vehicles has declined. No LPG passenger cars or trucks have been produced commercially in the United States since 2004. However, certified installers can retrofit vehicles to run on propane. Since the LPG is stored in high-pressure fuel tanks, separate fuel systems are required for bi-fuel vehicles that run on both LPG and conventional fuels. Propane conversions for light duty vehicles from gasoline to dedicated propane cost roughly between $4,000 and $12,000. • Energy content. LPG has about 25 percent less energy than a gallon of gasoline, increasing fuel consumption and reducing range. As with CNG vehicles, larger storage tanks can be installed to increase range, but the additional weight will displace payload capacity.

30 airport Ground Support equipment (GSe): emission reduction Strategies, Inventory, and tutorial Electric Vehicles. Electric vehicles (EVs) are powered exclusively by an electric motor. Most EVs operate with electricity that is stored in a battery that must be recharged by plugging into a suitable outlet. Batteries are also recharged by regenerative braking, a method of storing the kinetic energy from braking into elastic potential energy that can be redistributed and used to power the car. Whenever an EV is not accelerating, the vehicle’s momentum can be used to gen- erate electricity. EVs can run on either alternating current (AC) or direct current (DC) power. Unlike vehicles powered by fossil fuels, EVs can also receive their power from nuclear power, solar power, tidal power, wind power, or other sources. The characteristics of electric vehicles are as follows: • Availability. Presently, approximately 10 percent of the 72,000 GSE units currently in use in the United States are electric. Thus, more GSE units are electric than any other alterna- tive fuel type. • Operational costs. Compared to the volatile cost of fossil fuels, the price of electricity is much more stable. The fuel cost of driving an EV is normally less than that for a gasoline or diesel vehicle, although actual cost depends on the cost of electricity per kilowatt-hour and the energy efficiency of the vehicle. Estimating that electricity costs 13 cents per kilowatt-hour, the fuel for an EV with an energy efficiency of 3 miles per kilowatt-hour costs about 4 cents per mile. This translates to only $1 per gallon if 25 miles per “gallon” is assumed. EV charging rates may also vary by time of use (peak vs. non-peak) and season. As an example, the Metropolitan Airports Commission purchased a flat-bed two-seater Cush- man Motors e-Ride exv2 electric utility vehicle for $22,265 to be used by parking management staff. The utility vehicle contains a 72-volt AC motor with a driving range of 45 to 55 miles per charge. At Minneapolis-St. Paul International Airport (MSP), the EV can be powered for a cost of approximately $202 per year. Comparatively, MSP pays approximately $818 per year to fuel a Ford Escape Hybrid and $1,653 to fuel a Ford F-150 pickup truck. Some EV manufacturers include warranties to cover batteries for approximately 80,000 to 100,000 miles. Since the battery is expensive to replace, operators should consult with the dealer prior to purchasing an EV to come to a clear consensus on the expected battery life and warranty. • Energy efficiency. An EV can convert approximately 75 percent of the chemical energy stored in the batteries to power the wheels while an internal combustion engine (ICE) can only convert about 20 percent of the energy stored in gasoline. In stop-and-go operations, EVs are even more efficient, since electricity is not consumed while the vehicle is stopped (no idling). • Performance. The acceleration, speed, and handling of an EV can equal or exceed that of con- ventional ICE vehicles. EV operation is also much quieter than ICE vehicles. However, EV’s have limited towing ability over longer distances and thus cannot be used for some operations (e.g., towing an aircraft from a gate to a maintenance hangar). EVs may also have difficulty hauling larger loads up inclined ramps. • Maintenance. EVs require less maintenance than ICE vehicles. No oil changes, belts, spark plugs, fuel injectors, or emissions tests are involved. The completely sealed cooling systems do not require refilling, replacement, or flushing. EVs also have fewer moving parts, which results in reduced inventories, lower operating capital, and fewer spare parts. Regenerative braking also reduces wear and tear on brake pads. • Conversions. The cost of converting a gasoline-powered vehicle to an EV can be high although it could potentially be offset by lower operational and maintenance costs. Converting a GSE powered by an ICE to electric power requires completely removing the engine and adding a battery pack, cabling, electric motor, and metering equipment. Therefore, converting to elec- tric power is most cost effective when the vehicle’s engine has reached the end of its life cycle or needs to undergo expensive repairs. Instead of purchasing a new ICE, converting to electric power could be considered.

research Findings and products 31 Converting to electric power does not require certification from the U.S. EPA. However, vehicles that have a gross vehicle weight rating of less than 10,000 pounds, use more than 48 volts of electricity, and have a maximum speed greater than 25 miles per hour must meet Federal Motor Vehicle Safety Standard 305: Electrolyte Spillage and Electrical Shock Prevention. • Range anxiety. EVs have a limited battery storage capacity that must be replenished by plug- ging the EV into an electrical power source. Neighborhood electric vehicles (NEVs), com- monly found at airports, are limited to operating on roads with speed limits of 35 miles per hour. However, since NEVs are limited to speeds of 35 miles per hour, NEVs are not consid- ered light-duty vehicles and are not eligible for fleet credit under the EPAct of 1992. Battery packs are also heavy, take up considerable vehicle space, are expensive, and may need to be replaced over the life cycle of the EV. • Charging stations. The National Electrical Code (NEC) has established three distinct plug-in electric vehicle (PEV) charging station levels. Each NEC level describes the amount of power that can be supplied to the vehicle to be charged (the more power delivered, the faster the charge). The three NEC levels are defined in Table 3-6. NEC Level II charging is the EV industry standard. The Society of Automotive Engineers (SAE) has approved a standard plug known as SAE J1772. The cost to provide recharging outlets at existing parking sites can be expensive. The cost for a Level II station, which includes engineering, permitting, hardware, weather-proofing, and service costs, is approximately $10,000 per outlet for the first two new outlets; for more than two outlets, the costs would drop to approximately $2,000 per outlet. Installation of recharg- ing stations at surface parking lots is typically more expensive, because trenching is typically required. At some airports, GSE may be able to share power with the electric motor used to power the jetway for passenger boarding since it is only used a few minutes per hour. The electrical circuit may be able to support charging stations when the jetway motor is not being used. The circuit can also reduce installation costs since wire and conduit runs are shorter. Other factors to consider prior to installing an EV charging station include airport layout, regulations, and traffic patterns to and from charging stations. • Recharge time. Fully recharging an EV may take from 4 to 8 hours, although fast-charging sta- tions can be purchased to limit recharging times. However, even a “quick charge” to 80 percent capacity can take over 15 minutes. If conveniently located, GSE can be plugged into recharging stations overnight or during break periods/downtime (by recharging EVs overnight operators may be able to take advantage of off-peak rates to decrease the cost of powering EVs). Hydrogen. The simplest and most abundant element in the universe, hydrogen can be pro- duced from fossil fuels, biomass and other renewable energy sources, or by electrolyzing water. Charging Level Voltage (VAC) Current (AMPS) Power (kVA) Input Phase Standard Outlet Estimated Full Charge Time Level I 120 12 1.44 Single NEMA 5-15R (Standard 110v outlet for U.S.) 8-14 hours Level II 208/240 32 6.7/7.7 Single SAE J1772/3 4-8 hours Level III 480 400 192 Three No standard. Some adopting Tokyo Electric Power Company < 1 hour Source: Thomason (2009). Table 3-6. National Electrical Code plug-in electric vehicle charging levels.

32 airport Ground Support equipment (GSe): emission reduction Strategies, Inventory, and tutorial Hydrogen vehicles either convert the chemical energy of hydrogen into torque by combustion or electrochemical conversion in a fuel cell. Similar to ICE vehicles that combust gasoline or diesel fuel, hydrogen vehicles with ICEs burn hydrogen in the engine to produce energy that powers the vehicle. In a fuel cell, hydrogen reacts with oxygen to produce electricity that powers an electric traction motor. The characteristics of hydrogen are as follows: • Energy content. At 52,000 BTU per pound, hydrogen has the highest energy content per unit weight of any known fuel; this is approximately three times the energy of a pound of gasoline. Therefore, the process of converting hydrogen to energy using engines or fuel cells is much more efficient than the comparable gasoline counterparts. • Availability. No fuel-cell vehicles powered with hydrogen are available yet for sale. Hydrogen is available only as an industrial or scientific chemical product, not as a bulk fuel. No bulk hydrogen distribution infrastructure exists near the scale of that for fossil fuels. Transporting hydrogen is also difficult since it must be refrigerated to maintain a liquid state. • Distribution. Generating hydrogen, transporting it via truck or pipeline, and storing it aboard the vehicle may be an inefficient and expensive process. Similar to CNG, hydrogen typically requires heavy tanks or insulating bottles if stored as a super-cold liquid. • Lifespan. Hydrogen fuel cells have less than half of the lifespan of a traditional ICE vehicle (about 1,900 hours or 57,000 miles). • Storage requirements. The amount of energy contained in 1 gallon of gasoline is equivalent to the amount of energy stored in 2.2 pounds of hydrogen gas; thus, a light-duty fuel-cell vehicle must store from 11 to 29 pounds of hydrogen to drive 300 miles or more. Storing this much hydrogen on a vehicle would require more space than the trunk size of a typical car. Since hydrogen technology is still in its infancy, expensive, and not readily available, using hydrogen in GSE was not evaluated further. Hybrid Electric Vehicles. In a hybrid electric vehicle (HEV), a small ICE is connected to an electric generator. Electric power is combined with gasoline, diesel, or an alternative fuel to power the electric traction motors, which in turn power the wheels of the vehicle. The drive is electric (battery powered) at low speeds and powered by the main ICE at high speeds. The EPAct of 1992 did not originally consider HEVs as alternative-fuel vehicles. However, the National Defense Authorization Act for Fiscal Year 2008 amended the 1992 EPAct to include four new categories of vehicles as “alternative-fueled vehicles” under Section 30B of the Internal Revenue Service Code, including “a new qualified hybrid motor vehicle.” The characteristics of HEVs are as follows: • Range/gas mileage. Unlike in EVs, the batteries in HEVs do not need to be plugged in to recharge. HEVs also avoid the inconvenience of long charging times and the cost of charging infrastructure. Some HEVs can be driven up to 70 miles on a single gallon of gasoline. The electric motor provides additional power to assist the engine in accelerating, passing, or hill climbing, allowing for a smaller, more efficient ICE to be used. In some HEVs, the electric motor solely provides power for low-speed driving conditions where ICEs are least efficient. HEVs usually cost 5 to 7 cents per mile to operate while conventional ICE vehicles cost 10 to 15 cents per mile. To prevent wasted energy from idling, HEVs automatically shut off the engine when the vehicle comes to a stop and restart it as soon as the accelerator is pressed. Like in EVs, regen- erative braking systems in HEVs capture deceleration energy and convert it to electricity to propel the vehicle and increase overall efficiency. • Maintenance. HEVs must undergo the same maintenance procedures as conventional vehi- cles although spare parts may be more difficult to find and have a higher cost.

research Findings and products 33 Cost of Conventional Fuels vs. Alternative Fuels This subsection compares the cost of conventional petroleum-based fuels with the cost of alternative fuels, including the historical, current, and forecast costs. Alternative fuels are typically not subject to dramatic price fluctuations because they are less dependent on the price of crude oil (unlike petroleum fuel prices). However, depending on the type of alternative fuel and/or the percentage blend, some alternative fuels still fluctuate based on crude oil prices, national security, spikes in the cost of agricultural products, and other factors. Historical Cost. Figure 3-1 depicts the 11-year average cost of gasoline and diesel fuels compared to alternative fuels from 2000 to 2011 per gallon of gasoline equivalent (a discus- sion of the gallon of gasoline equivalent values is provided in the subsection Fuel Operating Cost Considerations). The cost fluctuations of gasoline and ultra-low sulfur diesel (ULSD) fuel prices compared to alternative fuels from January 2008 to October 2011 are shown in Table 3-7. Current Cost. The national average cost per gallon for gasoline, diesel, and alternative fuels in January 2012 is provided in Table 3-8. As shown, CNG had the lowest cost per gallon at $1.24 less than gasoline (on an energy-equivalent basis); E85 was 23 cents less per gallon than gasoline; and propane cost 29 cents less per gallon than gasoline. Compared to the cost of diesel, B20 prices were 9 cents higher and pure biodiesel (B100) prices were 34 cents higher per gallon. According to the U.S. Energy Information Administration, the world average gasoline and diesel fuel prices are predicted to increase from $2.35 and $2.44 per gallon, respectively, in 2009 to $3.69 and $3.89 per gallon, respectively, in 2035 (in 2009 dollars). Annual average diesel prices are anticipated to be higher than gasoline prices because of increased demand for diesel. With the estimated increases in the cost of gasoline and diesel fuels, alternative fuels are expected to become more affordable. For example, in 2022, the retail price of gasoline is anticipated to be $3.43 per gallon while the price of E85 is anticipated to be $2.68 on a gallon of gasoline equiva- lent (GGE) basis. (The following paragraphs discuss the gasoline equivalent basis.) Fuel Operating Cost Considerations When viewed separately from other operational cost factors, the cost per gallon of a fuel may be misleading. The energy content and location/availability of an alternative fuel, which are described below, should also be factored in to provide a more accurate estimate of fuel cost. Energy Content. Because of differing energy content per gallon for fuels, the price paid per unit of energy content differs from the price paid per gallon. Prices for the alternative fuels in terms of cost per GGE are generally higher than their cost per gallon because of their lower energy content. For example, 1.41 gallons of E85 are required to do the same work as 1 gallon of diesel fuel. Therefore, although E85 was priced at $3.14 per gallon compared to that of gasoline at $3.37 in January 2012, the cost for E85 is actually more expensive than gasoline on a GGE basis ($4.44 per gallon). Table 3-9 lists conversion factors that should be used to achieve a level playing field as either GGE or gallon of diesel equivalent (GDE). Taking these conversion factors into account, Table 3-10 lists the average fuel price of alterna- tive fuels in GGE and GDE from January 2008 to January 2012. Prices for all fuel types peaked in July 2008 and declined through January 2009. From January 2009 to April 2011, fuel prices have all increased, as illustrated in Figure 3-2. Location/Availability. The price of an alternative fuel is dependent upon where the fuel is manufactured and blended and where fueling infrastructure is located. For example, while gasoline and diesel consumption is highest along America’s coasts, most ethanol plants are con- centrated in the Midwest where it is absorbed in local and regional markets.

GGE = gallon of gasoline equivalent Source: U.S. Department of Energy (2012b). Some figures in this report have been converted from color to grayscale for printing. The electronic version of the report (posted on the web at www.trb.org) retains the color versions. Figure 3-1. U.S. 11-year average fuel prices in cost per gallon of gasoline equivalent.

Table 3-7. Average U.S. fuel prices. National Average Cost Per Gallon 2008 2009 2010 2011 Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul Oct Gasoline $2.99 $3.43 $3.91 $3.04 $1.86 $2.02 $2.44 $2.64 $2.65 $2.84 $2.71 $2.78 $3.08 $3.69 $3.68 $3.46 Diesel $3.40 $4.14 $4.71 $3.65 $2.44 $2.27 $2.54 $2.79 $2.87 $3.02 $2.95 $3.07 $3.45 $3.62 $3.95 $3.81 Compressed natural gasa $1.93 $2.04 $2.34 $2.01 $1.63 $1.64 $1.73 $1.86 $1.85 $1.90 $1.91 $1.93 $1.93 $2.06 $2.07 $2.09 Ethanol (E85) $2.51 $2.87 $3.27 $2.82 $1.81 $1.88 $2.13 $2.27 $2.38 $2.42 $2.30 $2.44 $2.75 $4.52 $3.26 $3.19 Propane $3.12 $3.15 $3.14 $3.38 $2.73 $2.58 $2.48 $2.69 $2.99 $2.89 $2.90 $2.85 $3.05 $4.41 $3.09 $3.06 Biodiesel (B20) $3.37 $3.98 $4.66 $4.04 $2.67 $2.49 $2.69 $2.88 $2.96 $3.12 $3.06 $3.14 $3.50 $3.69 $4.02 $3.91 Biodiesel (B100) $3.69 $4.31 $4.88 $4.64 $3.47 $3.27 $3.08 $3.19 $3.59 $3.57 $3.75 $3.82 $4.05 $4.26 $4.19 $4.18 aCompressed natural gas is measured on an energy-equivalent basis (gallon of gasoline equivalent). Source: Data from U.S. Department of Energy, Energy Efficiency and Renewable Energy. “Clean Cities Alternative Fuel Price Report,” Clean Cities, January 2008 - January 2012, www.afdc.energy.gov/afdc/price_report.html (accessed April 11, 2012).

36 airport Ground Support equipment (GSe): emission reduction Strategies, Inventory, and tutorial Table 3-11 identifies how alternative-fuel prices for the month of January 2012 varied based on U.S. region. As shown, the location of each fuel pump relative to the production facility and customer base is an important factor to consider when estimating fuel price. For example, the cost of B100 varied by as much as $1.42 per gallon between the Gulf Coast region ($3.50) and the Central Atlantic region ($4.92). Price also varies depending on whether the purchaser of alternative fuel buys in bulk supply from the producer via rail, pipeline, or barge (spot price); a limited supply from a refueling truck (rack price); or at a traditional pump (retail price). Furthermore, the retail price is also influ- enced by whether the fueling station is branded or unbranded and the degree of competition in the vicinity of the station. Biofuels are not often shipped via pipeline so they are generally blended at the local wholesale terminal. Not all fueling stations sell high percentage biofuel (ethanol and biodiesel) blends such as E85 or B100. Biofuel prices are contingent upon seasonal availability; factors involved in growing, processing, and distributing biofuels can contribute to price fluctuations. The use of low-level biofuel blends such as E10 and B5 can be influenced by local air quality regulations or federal and state renewable fuel standards. Additionally, as more alternative-fuel producers and suppliers enter the market, competition will likely increase the available supply of biofuels, potentially lowering the price of biofuels. Other Fuel Cost Considerations. Federal, state, and local tax provisions may be applicable for certain fuels used for off-highway business use. Fuel cost adjustments may include taxes or tax credits such as excise taxes, alcohol fuel credits, biofuel tax credits, gasoline tax refunds, etc. Fuel Lower Heating Value Conversion Factor to Dollars per Gallon of Gasoline Equivalent Conversion Factor to Dollars per Gallon of Diesel Equivalent Gasoline 115,400 BTU/gal 1.00 – Diesel 128,700 BTU/gal – 1.00 Compressed natural gas 960 BTU/ft3 1.00 1.12 Ethanol (E85) 75,670 BTU/gal 1.41 1.58 Propane 83,500 BTU/gal 1.38 1.54 Biodiesel (B20) – 0.91 1.02 Biodiesel (B100) 117,093 BTU/gal 0.99 1.10 Source: U.S. Department of Energy (2012a). Table 3-9. Energy content equivalency factors. National Average Cost Per Gallon January 2012 Gasoline $3.37 Diesel $3.86 Compressed natural gasa $2.13 Ethanol (E85) $3.14 Propane $3.08 Biodiesel (B20) $3.95 Biodiesel (B100) $4.20 a Compressed natural gas is measured on an energy-equivalent basis (gallon of gasoline equivalent). Source: U.S. Department of Energy (2012a). Table 3-8. Average cost per gallon of fuel.

Fuel 2008 2009 2010 2011 2012 Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul Oct Jan Cost per Gallon of Gasoline Equivalent Gasoline $2.99 $3.43 $3.91 $3.04 $1.86 $2.02 $2.44 $2.64 $2.65 $2.84 $2.71 $2.78 $3.08 $3.69 $3.68 $3.46 $3.37 Diesel $3.05 $3.71 $4.22 $3.27 $2.19 $2.04 $2.27 $2.50 $2.57 $2.71 $2.65 $2.75 $3.09 $3.62 $3.54 $3.42 $3.46 Compressed natural gas $1.93 $2.04 $2.34 $2.01 $1.63 $1.64 $1.73 $1.86 $1.85 $1.90 $1.91 $1.93 $1.93 $2.06 $2.07 $2.09 $2.13 Ethanol (E85) $3.55 $4.06 $4.62 $3.99 $2.56 $2.66 $3.01 $3.21 $3.36 $3.42 $3.25 $3.45 $3.89 $4.52 $4.60 $4.51 $4.44 Propane $4.31 $4.36 $4.34 $4.67 $3.77 $3.56 $3.43 $3.72 $4.13 $3.99 $4.01 $3.93 $4.22 $4.41 $4.26 $4.23 $4.26 Biodiesel (B20) $3.08 $3.63 $4.25 $3.69 $2.43 $2.27 $2.45 $2.63 $2.70 $2.85 $2.79 $2.86 $3.19 $3.69 $3.67 $3.57 $3.61 Biodiesel (B100) $3.63 $4.24 $4.81 $4.58 $3.42 $3.22 $3.03 $3.14 $3.54 $3.52 $3.69 $3.76 $3.99 $4.26 $4.13 $4.12 $4.14 Cost per Gallon of Diesel Equivalent Gasoline $3.33 $3.82 $4.36 $3.39 $2.08 $2.26 $2.72 $2.95 $2.96 $3.17 $3.03 $3.10 $3.43 $4.12 $4.10 $3.85 $3.76 Diesel $3.40 $4.14 $4.71 $3.65 $2.44 $2.27 $2.54 $2.79 $2.87 $3.02 $2.95 $3.07 $3.45 $4.04 $3.95 $3.81 $3.86 Compressed natural gas $2.15 $2.27 $2.61 $2.24 $1.82 $1.83 $1.93 $2.08 $2.07 $2.12 $2.13 $2.15 $2.15 $2.30 $2.30 $2.33 $2.38 Ethanol (E85) $3.96 $4.53 $5.15 $4.44 $2.86 $2.96 $3.36 $3.58 $3.75 $3.81 $3.63 $3.84 $4.33 $5.04 $5.14 $5.02 $4.96 Propane $4.80 $4.86 $4.84 $5.21 $4.21 $3.97 $3.82 $4.15 $4.61 $4.45 $4.01 $4.39 $4.70 $4.92 $4.76 $4.71 $4.75 Biodiesel (B20) $3.32 $4.05 $4.74 $4.11 $2.71 $2.53 $2.74 $2.93 $3.02 $3.18 $3.11 $3.19 $3.56 $4.12 $4.09 $3.98 $4.02 Biodiesel (B100) $4.05 $4.73 $5.36 $5.10 $3.82 $3.59 $3.38 $3.50 $3.95 $3.92 $4.12 $4.19 $4.45 $4.75 $4.60 $4.59 $4.61 Source: Data from U.S. Department of Energy, Energy Efficiency and Renewable Energy. “Clean Cities Alternative Fuel Price Report,” Clean Cities, January 2008 - January 2012, www.afdc.energy.gov/afdc/price_report.html (accessed April 11, 2012). Table 3-10. Average U.S. fuel prices in gallon of gasoline and diesel equivalence.

38 airport Ground Support equipment (GSe): emission reduction Strategies, Inventory, and tutorial Additionally, bulk fuel purchase discounts or in the case of electric vehicles, off-peak electrical charging usage should be considered in the overall fuel costs for each GSE fuel type. Non-Fuel Cost Considerations Beyond the costs for purchasing the fuel, there are indirect costs that should also be considered when evaluating alternative-fuel GSE. Labor. Labor costs represent the single largest expense of the total cost of owning and operating GSE. As shown in Table 3-12, ramp labor represents over 80 percent of the total Fuel Average Cost Per Gallon New England Central Atlantic Lower Atlantic Mid- west Gulf Coast Rocky Mountain West Cost National Average Gasoline $3.60 $3.46 $3.46 $3.29 $3.15 $3.09 $3.68 $3.37 Diesel $4.05 $3.83 $3.82 $3.74 $3.77 $3.77 $4.15 $3.86 Com pressed natural ga s 1 $2.42 $2.28 $1.69 $1.84 $1.89 $1.69 $2.38 $2.13 Ethanol (E85) $3.76 $3.23 $3.23 $3.06 $3.05 $2.99 $3.35 $3.14 Propane $3.37 $2.84 $3.17 $2.98 $2.89 $2.97 $3.36 $3.08 Biodiesel (B20) $3.96 $4.07 $3.89 $3.71 $3.91 $3.93 $4.13 $3.95 Biodiesel (B100) $3.73 $4.92 $3.83 $4.16 $3.50 $4.32 $4.16 $4.20 1 Co mp ressed natural gas is measured on an energy-equivalent basis (gallon of gasoline equivalent). Source: Data from U.S. Department of Energy, Energy Efficiency and Renewable Energy. “Clean Cities Alternative Fuel Price Report,” Clean Cities, January 2012, www.afdc.energy.gov/afdc/price_report.html (accessed April 11, 2012). Table 3-11. Regional variance in alternative-fuel prices in January 2012. Source: U.S. Department of Energy, Energy Efficiency and Renewable Energy. “Clean Cities Alternative Fuel Price Report,” Clean Cities, January 2008 - January 2012, www.afdc.energy.gov/afdc/price_report.html (accessed April 11, 2012). Figure 3-2. Average nationwide (U.S.) fuel prices in cost per gallon of gasoline equivalent.

research Findings and products 39 cost to own and operate baggage tractors. Alternative-fuel equipment should be evaluated to determine if their operation could reduce labor costs and/or free up labor resources for other non-fuel emissions-related ground handling operations. Alternative-fuel equipment should be evaluated for the potential to reduce the time to adequately train the operator and/or improve operational learning curves and efficiencies while reducing safety-related incidents and accidents. Other labor cost reduction strategies include the adjustment to the work schedule. The labor schedule for the ground servicing of aircraft is derived by the aircraft schedule. Where it may not be possible for an airline to support point-to-point passenger service, the hub-and-spoke schedule enables the airlines, especially large “legacy” carriers, to support a vast system network. Aircraft arrive from the spoke stations to the hub station in a scheduled arrival bank. Passengers arriving at the hub station then connect to a closely timed departure bank resulting in the short- est overall travel time for the connecting passenger. While this schedule is preferable to the pas- senger, a “peaked” hub-and-spoke schedule places the greatest demand on GSE and associated labor resources and increases the potential for airline arrival and departure delays and resultant aircraft fuel expenditures and emissions. Cost Type Per Tractor Total (25 Tractors) Costs per Tractor Annual Percentage of Total Annual Annual Non- labor Percentage of Total Annual Non-labor Ownership Costs Initial Cost $25,000 $625,000 Average Life (years) 20 $1,250 1.2% $1,250 10.8% GSE Storage Facility (capital costs)a ($ per 20-year period) $100,000 Average Storage Costs ($ per tractor) $200 0.2% $200 1.7% Residual Resale Valueb $2,500 $62,500 -$125 -0.1% -$125 -1.1% Total Ownership Costs Per Year $1,325 $1,325 Operating Costs Utilization/day (hours) 8 200 Utilization/year (hours) 2,920 73,000 Lifetime Utilization (hours) 58,400 1,460,000 Maintenance (annual hours) 100 2,500 Maintenance (lifetime hours) 2,000 50,000 Maintenance Labor Rate ($40 per hour) $4,000 3.9% Maintenance Parts $2,000 1.9% $2,000 17.2% Annual Training Costs $1,000 1.0% $1,000 8.6% Ramp Labor ($30 per hour) $87,600 84.9% Fuel Burn per Hour ($2.50 per gallon @ 1 gallon per hour) $7,300 7.1% $7,300 62.8% Total Operating Costs Per Year $101,900 $10,300 TOTAL ANNUAL COSTS $103,225 100.0% $11,625 100.0% Average Cost per Hour of GSE Utilization $35.35 a Assume storage capital expenditure for GSE facility with 20-year life. b Depreciation, tax deductions, and cost of capital not considered. Table 3-12. Example of baggage tractor (gasoline/diesel) maintenance cost considerations.

40 airport Ground Support equipment (GSe): emission reduction Strategies, Inventory, and tutorial Alternatively, “de-peaking” the schedule places less demand on labor and equipment resources. In a de-peaked schedule, arriving and departing aircraft are scheduled more uniformly through- out the day; thus, fewer resources are required for any given hour in the schedule compared to that of a peaked schedule. For example, consider a simplified 16-aircraft operation at an airport (eight arrivals and eight departures per day): a peaked schedule could consist of four departures at 8:00 a.m., four arrivals at 12:00 noon, four departures at 4:00 p.m., and four arrivals at 8:00 p.m.; a uniformly distributed schedule could have one departure at 8:00 a.m., an arrival at 9:00 a.m., and alternating arrivals and departures each hour throughout the day. While the GSE fuel cost and GSE emissions may be iden- tical in each of these cases for any given GSE type, the variable labor and GSE inventory require- ments for the peaked schedule could be as much as four times that of the de-peaked schedule in this example. It should be noted, however, that in the de-peaked schedule, the average passenger connect times may be expected to increase, which may result in the loss of market share to airline competitors, depending on the alternatives that were available to the passenger. It is the airline passenger that creates the demand for air travel, the demand that the travel occur during certain times of the day, and the demand that layovers between connecting flights be limited. To de-peak air travel may require re-regulation and subsequent restructuring of the airline industry. Other Non-Fuel Cost Considerations. Federal, state, and local tax provisions may be appli- cable for certain vehicles used in off-highway-related businesses. In addition to the purchase price of equipment, net adjustments should include tax credits such as credits for the purchase of alternative-fuel vehicles. Other tax-related considerations would include the applicability of business-related Section 179 depreciation expense for GSE. Other cost considerations include GSE insurance coverage for damage, liability, and business interruption loss, cost of capital (funding costs to purchase GSE), and administration overhead. Cost of Alternative-Fuel GSE The cost of an alternative-fuel GSE vehicle varies heavily based on several airport-specific factors such as the type of GSE, quantity of GSE purchased (i.e., bulk rates), existing contracts with the airport, the manufacturer, performance capabilities, custom features, lighting and sig- nage, etc. Alternative-fuel GSE, particularly electric, LPG, and CNG vehicles, normally have a higher up-front cost than gasoline or diesel GSE. In some cases, low-level blends of ethanol and biodiesel may be useable in existing vehicles without modifications (although additional mainte- nance is required and caution should be taken during the transitioning process). On average, the initial cost of electric GSE can be 30 to 35 percent more expensive than gasoline GSE. Similarly, the higher cost of the fuel cylinders and tanks means that light-duty CNG and LPG vehicles cost from $3,500 to $6,000 more than their gasoline-powered counterparts. Life-cycle costs, which incorporate fuel cost savings, maintenance costs, vehicle lifespan, and infrastructure, must also be considered or else it would not make financial sense to convert to electric, LPG, or CNG with existing technology. Cost savings are usually realized when consider- ing life-cycle cost benefits. Additionally, non-cost factors, such as the benefits from improved air quality, GSE performance, and airport marketing and public image, should also be considered. Maintenance Costs When considering total operating costs, the GSE airport administrator must also consider maintenance costs, which include not only maintenance materials and supplies, but also the hourly rates for mechanics’ wages. The GSE administrator should ensure that all GSE propulsion systems are warranted by the original equipment manufacturer to operate on alternative fuels; however, converted propulsion systems are typically not included under the vehicle warranty. As a representative example (for consideration purposes only), Table 3-12 shows how the mainte-

research Findings and products 41 nance cost (labor and parts) of a typical gasoline or diesel baggage tractor can amount to a large percentage of the total life-cycle cost. Biofuel GSE. Because biofuels (ethanol and biodiesel) are natural solvents, they may degrade rubber compounds found in fuel hoses, gaskets, and fuel pump seals (especially higher blends); this degradation could result in clogged filters, increasing maintenance costs compared to con- ventional fuels (although engines manufactured after 1993 typically do not experience prob- lems). If the filter ruptures, sediment could travel into the fuel lines, pump, and injectors, causing expensive repair needs. Also, since biofuels are greater attractants of water than petroleum-based fuels, they promote microbial growth in fuel tanks. Microbial growth may cause engine failure, fuel filter clogging, and corrosion. Therefore, if GSE uses ethanol or biodiesel, routine mainte- nance should be performed to check for and replace clogged fuel filters. The GSE administrator should prepare for increased engine fuel filter and fuel storage filter replacements and maintain equipment inventories accordingly. Prior to fueling GSE with high blends of biofuels, precautions should be taken to verify that no incompatible rubber compounds are in the fueling system. Maintenance personnel should change the fuel filter following the use of the first tank of bio- fuels, and fuel filters at dispensing units should be changed when operators notice that the flow of fuel slows. Periodic fuel testing may also be required to ensure fuel quality. Similarly, mainte- nance personnel should periodically check for free water at the bottom of fuel storage tanks. If biofuels must be stored for over 6 months, additional maintenance and labor may be required to prevent and/or mitigate fuel contaminated by water (e.g., seasonal fuel tank draining). To reduce the potential for cold temperature fuel gelling of biofuels, the GSE administrator may need to purchase additives such as kerosene, filter and block heaters, and/or indoor storage space, adding to the maintenance cost. Electric GSE. EVs require no oil changes, belts, spark plugs, fuel injectors, or emissions testing; do not require refilling, replacement, or flushing of cooling systems; and have smaller engine part inventories. EVs (as well as HEVs) also reduce wear and tear on brake pads through regenerative braking, a process that converts kinetic energy from braking to electricity that is stored in the battery. Therefore, maintenance costs (parts and labor) are less than for GSE fueled with gasoline, diesel, or biofuels. Comparing maintenance costs per hour of conventional fuel GSE to electric GSE is inaccurate since there is no idling time in an EV. Thus, when considering the maintenance cost per hour of a gasoline or diesel GSE to be equal to the cost per hour of an electric GSE, the electric GSE can accomplish 65 to 70 percent more work for the same amount of maintenance; if maintenance is scheduled by hours, a gas unit is maintained almost 2.5 times more often than an electric. CNG and LPG GSE. The oil in a CNG vehicle does not need to be changed as frequently as a gasoline or diesel vehicle because CNG burns cleaner, producing fewer oil deposits. LPG has an octane rating from 104 to 112 (compared with 87 to 92 for conventional gasoline fuel), which helps prevent engine knocking. Because of LPG’s low carbon and oil contamination character- istics, the engine life of a LPG vehicle can be up to two times that of gasoline engines. Unlike with biofuels, no cold temperature problems are associated with LPG since the fuel mixture is completely gaseous. Training Compared to conventional-fuel GSE, training costs for alternative-fuel GSE may be higher. Training may help GSE operators identify when GSE charging or alternative-fuel infrastructure is malfunctioning and when potential safety hazards exist. For example, since LPG and CNG are clear and odorless, GSE operators may need to be briefed on adding an odorant to the fuel mixture and identifying signs of leaks in fuel tanks.

42 airport Ground Support equipment (GSe): emission reduction Strategies, Inventory, and tutorial Operators of electric GSE should also be informed of the charging time required, when the GSE needs to be recharged to ensure demand is met, and the best time to charge the vehicle if peak electrical usage rates apply. To reduce fuel consumption and maintenance costs, the GSE administrator may consider providing fuel-efficient driving and vehicle-operating training annually to GSE drivers, regardless of the fuel type. The training can help ensure that GSE are used as intended and that driving techniques are used that reduce fuel consumption, greenhouse gas emissions, and accident rates. Cost of Infrastructure New fueling infrastructure may be necessary to support a fleet of alternative-fuel GSE. In addition to costs, the space available to accommodate new fueling infrastructure must also be considered. For example, electric charging infrastructure, LPG, or CNG fuel tanks may be required if no existing infrastructure nearby the airport is available. Although ethanol and biodiesel could be stored in existing gasoline and diesel infrastructure (after appropriate cleaning), supplementary fuel tanks would still be required unless the entire fleet is transitioned to run on biofuels. CNG and LPG fueling stations have high installation costs; for example, since a CNG fueling facility requires dedicated supply lines, compression apparatus, storage cylinders, and special dispensers, the construction cost ranges from $400,000 to $600,000. The high cost also factors in the need for CNG and LPG fuel tanks to be designed to withstand high internal pressures and be resistant to accidental punctures. Electric charging infrastructure can be expensive at an airport without sufficient existing elec- tric power available. Although some electric GSE could be plugged into a traditional 120-volt outlet, the time to fully charge the vehicle could take over 8 hours. A Level II or Level III “quick charge” station is likely required to satisfy fleet demand during peak air travel periods. The cost of a charging station can be anywhere from $10,000 (Level II) to $60,000 (Level III) depending on existing electrical outlets, wiring, power demand, capacity, and the quantity purchased. However, bridge electric power sharing or other opportunities may be available to extract power for charging without the need for additional infrastructure (or could reduce installation costs of new infrastructure). For instance, a jet bridge only uses the power that is supplied to it for about 5 percent of the day; the remaining 95 percent could be used for electric GSE charging. Life-Cycle Cost Considerations Since alternative-fuel GSE and supporting infrastructure typically have a higher initial cost than conventional-fuel GSE, airports with higher annual fuel consumption rates may have a quicker return on investment when purchasing alternative-fuel and/or electric GSE compared to lower fuel-use airports. The break-even fuel cost varies based on the type of GSE, the purchase price, available funding, required maintenance, type of fuel used, infrastructure costs, and other factors. For instance, using electric bag tractors, belt loaders, cargo loaders, lavatory service trucks, and narrow-body aircraft tractors reduces fuel, maintenance, and high spare-part and equipment costs. As an example of life-cycle cost considerations, the cost-benefit analysis of electric GSE per- formed by Idaho National Laboratories is described in the following paragraphs. Idaho National Laboratories GSE Cost-Benefit Analysis Study. In February 2007, Idaho National Laboratories performed a study to evaluate the costs associated with operating baggage tractors, belt loaders, and pushback tractors. A cost model was developed to assist airlines and other stakeholders in future evaluations of deploying GSE. The approach included visiting four airports and working with two airlines to obtain data on GSE capital, operating, maintenance, and infrastructure costs.

research Findings and products 43 The study found that electric GSE has lower operating costs than ICE GSE for the baggage tractor, belt loader, and pushback tractor. Capital costs for new ICE GSE are significantly lower than for new electric GSE. The payback time for electric GSE ranges from 3 to 7 years when no cost-sharing is provided. With cost-sharing and/or grants, the payback time for electric GSE can be reduced to 3 years or less, with life-cycle cost savings accruing over the life of the GSE. The study also showed that converting old ICE vehicles to electric or implementing group purchases can help lower the cost of electric GSE. Techniques such as utilizing existing bridge supply power and utilizing smart power-sharing charge systems to reduce supply requirements can be used to help lower infrastructure costs. VALE Program Funding As discussed previously, the FAA established the VALE Program in 2005 to help airport spon- sors meet their obligations under the CAA and to assist regional efforts to meet the NAAQS. The program provides sponsors with financial and regulatory incentives to increase their investments in proven, commercially available low-emission technology. Eligible alternative fuels under the VALE Program include fuels that are primarily non- petroleum based, are cleaner burning than conventional petroleum-based fuels, and lessen U.S. dependence on foreign oil. The VALE Program follows the definition of alternative fuels established by the U.S. EPA and the U.S. DOE as part of the EPAct. Hybrid vehicles that com- bine gasoline or diesel engines with an electric motor are also eligible. Eligible hybrids must substantially displace the vehicle’s gasoline or diesel fuel use and meet the VALE Program’s low-emission standards. Vehicles and engines that are eligible for funding under the VALE Program must either be U.S. EPA certified (new vehicles) or U.S. EPA verified (retrofit technology). Infrastructure development funded under the VALE Program, such as the installation of EV charging stations, must be located on-airport. Airport sponsor ownership of equipment is required in most instances and generally preferred to ensure accountability and to avoid situations where tenants relocate or experience financial difficulties. Funding for alternative-fuel and EV charging stations is limited to demand that is directly related to eligible VALE activities, excluding other airport or facility electrification needs that otherwise may or may not be AIP or PFC eligible. No more than 10 percent of station capacity can be dedicated for public use. All vehicles and equipment purchased or converted under VALE must be an integral part of the aeronautical, transportation, security, or maintenance services at the airport, used on a regular basis in normal operation of the airport, and stored and maintained within the airport boundary. Vehicles can only be used outside the airport boundary if such use is minor, intermit- tent, and related to its primary mission to deliver airport services at the airport. As an example, 25 electric GSE units (three aircraft tow tractors, nine baggage tractors, five belt loaders, four stair trucks, and four lavatory/water trucks) and 13 recharging stations were purchased by the Westchester County Airport (New York) for $2.47 million in 2009. The GSE and charging stations were acquired with the assistance of a VALE grant of $1.1 million in addi- tion to assistance from the New York State Department of Transportation. 3.4.2 Environmental Considerations and Challenges This subsection identifies and describes the principal environmental factors associated with owning and operating GSE with an emphasis on the use of alternative fuels. Because air qual- ity is the principal environmental consideration given to alternative-fuel GSE, air emissions are discussed first followed by the issues associated with water quality, noise, solid/hazardous wastes, etc.

44 airport Ground Support equipment (GSe): emission reduction Strategies, Inventory, and tutorial Emission Reduction Potentials and Penalties The fundamental physical and chemical properties of alternative fuels as they pertain to air emissions are presented in this section. Specifically, emissions of PM, NOx, CO, hydrocarbons (HC), and, where applicable, HAP/air toxics (AT) and greenhouse gas (GHG) emissions are discussed. The emissions reduction potentials and penalties compared to conventional fuels (i.e., gasoline and diesel) are also discussed. (For consistency with other sections, the fuels are presented in alphabetical order.) Biodiesel. Due to the production process, biodiesel is typically oxygenated (up to 10 per- cent) where conventional diesel contains no oxygen, which affects the engine combustion pro- cess. For example, researchers observed an increase in brake-specific fuel consumption (BSFC) of 18 percent when using biodiesel in a CI diesel engine when compared to conventional diesel fuel (Gumus 2010, Canakci 2007). These and other important physical and chemical properties of biodiesel are discussed further as they relate to air emissions. Although biodiesel has been shown by a majority of studies to reduce emissions of CO, HC, and PM from levels produced by conventional diesel, emission reduction potentials largely depend on the biodiesel blend percentage as well as the source feedstock of the fuel (Fazal et al. 2011). For example, measured CO emissions are generally reduced from conventional diesel lev- els due to the presence of oxygen in the biofuel (i.e., B100) and can range from between 9 and 17 percent using frying waste oils (Cheng et al. 2008, Utlu and Kocak 2008, Murillo et al. 2007), to between 18 and 33 percent using soybean (Canakci 2007, Haas et al. 2001, Qi et al. 2009) and rapeseed (Kegl 2008) oils, to 81 percent from mahua oil feedstock (Raheman and Ghadge 2007). Like CO, CO2 emission reductions through the use of biodiesel are variable and depend on the percentage of the biodiesel blend as well as the feedstock by which it was produced (Utlu and Kocak 2008, Cheng et al. 2008). B100 produced from soybean oil has been shown to reduce HC emissions from levels emitted using conventional diesel fuels by 27 to 55 percent (Canakci 2007, Haas et al. 2001, Qi et al. 2009). HC reductions within this range have also been reported for rapeseed oil (Kegl 2008), and for frying waste oil (Cheng et al. 2008). Concentrations of HAPs found within B100 yellow grease biodiesel, including those of acet- aldehyde, acrolein, benzene, 1,3-butadiene, formaldehyde, and naphthalene, were shown to increase over levels documented in ULSD fuel; however, with the exception of 1,3-butadiene, none of the increased concentrations were considered to be statistically significant (Holden et al. 2006). PM emissions and smoke measurements from combustion of a variety of biodiesel blends show reductions of up to 53 percent over conventional diesel (Haas et al. 2001, Qi et al. 2009, Nabi et al. 2009). As shown in Figure 3-3, adopting the use of biodiesel can greatly reduce emissions of pollut- ants such as CO, HC, and PM but may present penalties with respect to NOx emissions. Some CO HC PM NOx CO2 HAPs/AT Figure 3-3. Emission reduction potential/penalty of biodiesel compared to conventional diesel.

research Findings and products 45 studies on the effects of biodiesel on CI engine emissions have observed a reduction in NOx emissions over that of conventional diesel fuel of up to 25 percent (Utlu and Kocak 2008, Qi et al. 2009, Aydin and Ilkilic 2010). However, other studies have demonstrated an increase in biodiesel-related NOx emissions of up to 30 percent when compared to combustion emissions of conventional fuel engines (Nabi et al. 2009, Canakci 2007, Raheman and Ghadge 2007, Murillo et al. 2007). Notably, NOx increases resulting from biodiesel usage can be mitigated or offset with mechan- ical modifications to the engine or with fuel additives. For example, the U.S. Army tested B20 on U.S. Air Force GSE that was normally fueled with either regular diesel or JP-8 aviation fuel, and revealed that alteration of the injection timing as well as the installation of exhaust gas recircula- tion (EGR) systems lowered NOx emissions by up to 10 percent when compared to conventional diesel fuel (Yost 2005). Researchers noted a 4 percent increase in NOx over conventional diesel emissions when applying B100 produced from frying waste oil but were able to obtain reduc- tions in NOx of 6 and 8 percent when introducing methanol and fumigated methanol-based additives, respectively, to the B100 fuel. However, the researchers noted that the use of fumigated methanol additives increased the concentrations of NO2 emitted from the engines (Cheng et al. 2008). Others created a dual-fuel mix of biodiesel and biogas to achieve significant NOx emis- sion reductions over ULSD, when tests on the biodiesel component alone performed worse than ULSD, suggesting that biogas mixing is another means to compensate for the potential for elevated biodiesel NOx emissions (Yoon and Lee 2011). Compressed Natural Gas. Lower fuel density and higher octane levels relative to gasoline allow CNG to be combusted at higher compression ratios and higher temperatures within SI engines (Das et al. 2000), which affects fuel consumption and pollutant characteristics of the fuel (Aslam et al. 2006). Gasoline SI engines retrofitted to burn CNG typically reduce the level of CO by up to 80 percent of that produced by burning gasoline (Jahirul et al. 2010, Aslam et al. 2006) and effect reductions in CO2 on the order of 30 percent (Zarante and Sodre 2009). HC emissions can be reduced between 30 and 50 percent, depending on engine throttle conditions (Aslam et al. 2006, Jahirul et al. 2010). It has also been observed that, although the nonmethane component of HC emissions can be greatly reduced from that of gasoline, methane (CH4) emissions tend to increase due to the abundance of CH4 in the fuel (Korakianitis et al. 2011). High levels of CH4 in the exhaust of CNG-fueled vehicles also provide a mechanism for the production of increased levels of HAPs (i.e., formaldehyde and acetaldehyde) when compared to gasoline-fueled vehicles (Correa and Arbilla 2005); however, these levels are still lower than those measured for diesel fuel (Turrio- Baldassarri et al. 2006). NOx emissions from the use of CNG can be elevated when compared to emissions from gasoline use by as much as 41 percent (Jahirul et al. 2010). However, studies have observed 170 percent higher NOx levels in SI engines when compared to gasoline, and lower levels when compared to diesel fuel in dual-fueled CI engines (Korakianitis et al. 2011). Modifications of CI engine injection timing can reduce CNG-related NOx emissions and are often a function of the pilot fuel used to initiate combustion in the case of dual-fueled vehicles (Carlucci et al. 2008). Blending hydrogen (H2) with CNG causes NOx emissions to increase substan- tially at higher loads, even though the practice can further reduce carbon-related emissions (Bysveen 2007). Emissions of fine (i.e., PM2.5) and respirable (i.e., PM10) fractions of PM associated with CNG have been found to be greatly reduced from that of traditional diesel fuel; however, PM emis- sions of smaller size ranges were comparable to that of traditional diesel, suggesting that CNG emits similar amounts of ultrafine particulates to traditional diesel fuel (Ristovski et al. 2000a). Gasoline SI engines converted to accept CNG fuel show variable results with respect to PM,

46 airport Ground Support equipment (GSe): emission reduction Strategies, Inventory, and tutorial whereby CNG usage offered PM reductions with respect to some operating loads and speeds and increases with respect to others (Ristovski et al. 2000b, Ristovski et al. 2004). Notably, data from the U.S. EPA suggest that replacing diesel GSE with CNG equivalents, including aircraft pushback tractors, baggage tugs, loaders, carts, forklifts, ground power units and service trucks, can increase HC emissions anywhere between 5 and 215 percent, where replacing gasoline GSE of the same type can effect HC reductions of anywhere between 65 and 98 percent. CO emissions can decrease by between 20 and 55 percent by replacing gasoline GSE with CNG GSE but can increase by between 4,000 and 5,000 percent when compared to diesel- powered equivalents. Although many studies indicate NOx increases when using CNG rather than gasoline equipment, the U.S. EPA only reports increases (135 percent) with respect to some two-stroke gasoline equipment, and otherwise claims that an approximate 25 percent reduction in NOx is possible by converting gasoline equipment to CNG. When compared to diesel GSE, CNG GSE typically decreases NOx emissions between 55 and 80 percent depending on the type of equipment. Reductions of PM emissions by using CNG GSE are approximately 98 per- cent relative to diesel GSE, and reductions relative to gasoline GSE are variable and range between 15 and 98 percent. Finally, CO2 reductions made possible by replacing diesel and gasoline GSE with CNG equivalents range from 10 percent to up to 45 percent, respectively (U.S. EPA 1998). Liquefied Petroleum Gas. LPG consists of a mixture of propane and/or butane gases (and their chemical derivatives), which exhibit specific gravity two to three times lower than that of diesel fuel (Saleh 2008). LPG can cause decreased vehicle power output due to increased fuel displacement and lower thermal efficiency over that of conventional gasoline (Ceviz and Yuksel 2006), leading to potentially increased fuel consumption and some emissions. The U.S. EPA has documented HC reductions from replacing gasoline GSE (including air- craft pushback tractors, tugs, loaders, carts, forklifts, ground power units, and service trucks) with LPG-fueled equivalents of between 45 and 60 percent for four-stroke SI engines and up to 97 percent for two-stroke engines. However, emissions of HC from LPG equipment increased by up to 155 percent when compared to diesel vehicles. CO reductions in the same study were approximately 40 to 55 percent relative to four-stroke gasoline GSE and 20 percent relative to two-stroke GSE. CO emissions from LPG increased in upwards of 5,000 percent when compared to diesel-powered equivalents. With respect to NOx, LPG usage creates a reduction of up to 25 percent relative to four-stroke gasoline equipment and up to 80 percent relative to diesel-powered equipment. Emissions of PM for GSE using LPG decreased by as much as 98 percent relative to both two-stroke gasoline and diesel GSE, but decreased by only 15 to 35 percent when compared against four-stroke gasoline SI GSE. Lastly, CO2 emissions from LPG GSE compared to gasoline and diesel GSE were found to be variable, sometimes increasing by up to 15 percent for some equipment and decreas- ing by up to 40 percent for others (U.S. EPA 1998). A study confirmed the U.S. EPA’s findings of lowered PM emissions from LPG vehicles com- pared to gasoline vehicles but also noted that particle sizes increased slightly over those mea- sured from gasoline exhaust. The same study also concluded that CO2 emissions produced from LPG combustion effected a 15 percent decrease relative to gasoline equivalents but only found statistically significant results with respect to higher operating speeds (Ristovski et al. 2005). Saleh (2008) also expanded upon some of the U.S. EPA’s findings by uncovering that LPG reductions of NOx and CO relative to diesel fuel were highest when the engine was operat- ing at low load and when the LPG blend consisted of at least 30 percent butane. The research also indicated that application of EGR on LPG engines can further reduce observed emission reductions (Saleh 2008).

research Findings and products 47 Another study determined that LPG vehicles emit significantly more mercury (Hg) than conventional-fuel equivalents (Won et al. 2007). A similar elemental analysis of LPG exhaust also concluded that levels of manganese (Mn), vanadium (V), arsenic (As), and selenium (Se) are higher in LPG exhaust than in gasoline exhaust, regardless of operating speed (McKenzie et al. 2006). Further, air toxic species of fluorene, anthracene, and benzo(b)fluoranthrene were found to be elevated in LPG exhaust over that of gasoline exhaust at low engine power set- tings, while species fluoranthrene, pyrene, benzo(b)fluoranthrene, indeno(1,2,3-cd)pyrene, and dibenzo(a,h)anthracene were elevated over that of gasoline exhaust levels at high engine power settings (McKenzie et al. 2007). Electricity. Electric vehicles are classified as either pure battery electric vehicles, fuel cell electric vehicles, or hybrid electric vehicles. Electricity-powered vehicles are considered envi- ronmentally friendly because they do not typically produce direct exhaust-related air emissions. However, because electricity demand may increase due to the use of these vehicles, the source of electricity generation must be considered when evaluating the potential emissions savings. The air emission considerations for battery electric vehicles are discussed in the following sub- section; discussions of fuel cell electric vehicles and hybrid electric vehicles are in the Hydrogen subsection and Hybrid Electric subsection, respectively. Battery Electric Vehicles. Battery power is typically evaluated based upon the power density and energy density of the elements used in the battery, which indicate the power output and energy storage capabilities of the battery. The power and energy densities required to power a battery electric vehicle (BEV) drive train can be provided by the following types of batteries, from the best suited (i.e., greatest power output and energy storage potential) to the least viable (i.e., low power output and energy storage potential): • Lithium-ion (Li-ion) • Lithium-metal polymer (LiM-polymer) • Sodium-nickel chloride (commonly referred to as ZEBRA) • Nickel-metal hydride (Ni-MH) • Nickel-cadmium (Ni-Cd) • Lead-acid batteries These parameters are important with respect to air quality because they address the efficacy of the electric vehicle to perform work relative to conventional-fuel counterparts (i.e., power density) and the level of off-site energy production or purchases required to keep the vehicles operational (i.e., energy density). As indicated previously, the advantage of adopting BEVs comes from the defrayal of exhaust emissions generated by the operation of the equipment, albeit acknowledging the emissions that occur off-site due to the generation of additional electricity by fossil-fueled power plants. Nota- bly, the U.S. EPA performed an in-depth study on emissions reductions achievable by replacing existing four-stroke gasoline, LPG, and diesel baggage tractors with BEVs, assuming a worst-case scenario in which additional electricity would be purchased by a coal-fired power plant and a best-case scenario wherein electricity would be generated by a maximally controlled natural gas-fired facility. Figure 3-4 provides an overview of the results. The U.S. EPA’s results show the importance of off-site generation of power in evaluating net emission reductions from BEVs (Campanari et al. 2009). For HC, the U.S. EPA demonstrated that, in the best case, emissions would be reduced between 99.5 and 99.9 percent from those produced from gasoline, LPG, and diesel. In the worst case, HC emissions would be reduced between 92.4 percent (relative to diesel) and 98.2 percent (relative to gasoline). With respect to CO emissions, BEVs offer a 100 percent reduction relative to gasoline

48 airport Ground Support equipment (GSe): emission reduction Strategies, Inventory, and tutorial and LPG fuels, and 99.3 percent relative to diesel. Even the worst case offers 99.9 percent reduc- tions with respect to gasoline and LPG fuels, and 96.4 percent with respect to diesel. Real distinctions begin to appear based on power plant source fuel when evaluating the baggage tractor emission reductions of NOx, PM, and CO2 (U.S. EPA 1998): • Emission reductions of NOx from BEV, when compared to the best-case, natural gas-fired power plant scenario, are on the order of 97.4 percent (relative to LPG) to 99.4 percent (rela- tive to diesel). • When considering the worst-case, coal-fired power plant scenario, NOx reductions from BEV usage equal 18 percent relative to LPG, 38.5 percent when compared to gasoline, and 81.8 per- cent when considering diesel. • Indirect BEV PM emissions were found to decrease by 88.9 percent compared to gasoline and LPG GSE in the best-case scenario and by 99.6 percent from levels produced by diesel tractors. • The worst-case scenario showed PM emissions penalties from BEV operation on the order of 3,328 percent with respect to gasoline/LPG GSE and by 33.8 percent when compared to diesel GSE. • Baggage tractor BEV reductions of CO2 relative to gasoline, diesel, and LPG GSE approximate 75 percent when assuming the power is purchased from a natural gas-fired plant, but range between 29.9 percent (relative to LPG) and 41.2 percent (relative to gasoline) when purchased from a coal-fired plant. Hydrogen. Hydrogen can be used as an alternative fuel in differing ways: (1) as a com- bustion fuel in internal combustion engines (H2ICE), (2) as a feed gas in the fuel cell of a fuel cell electric vehicle (FCEV), and (3) as an additive to compatible conventional fuels (Sopena et al. 2010). Because hydrogen fuel contains no carbon, combustion yields little to no direct CO, HC, and CO2 emissions (Mohammadi et al. 2007). Researchers found that CO emissions from an SI H2ICE vehicle decreased with increasing engine speeds, were sourced to thermal degradation of lubri- cation oil, and were negligible compared to emissions from gasoline SI engines. CO2 emitted from lubrication oil in the same experiment exhibited the same relationship as CO but without any observable trend with respect to engine speed. When comparing BEVs with FCEVs, CO2 emissions were found to be up to 46.3 percent less in FCEVs due to the potential for BEVs to be powered with electricity generated from GHG-intensive sources such as coal-fired power plants (Thomas 2000). CO HC PM Gasoline Diesel LPG NOx CO2 HAPs/AT Gasoline Highly dependent upon source fuel used at electrical generation facility Diesel LPG Figure 3-4. Emission reduction potential/ penalty of BEV compared to conventional and other fuels.

research Findings and products 49 NOx emissions from combustion of H2ICE fuel is a function of the fuel-to-air ratio of the fuel and can be constrained using NOx traps, water injection, and EGR applications (Verhelst and Wallner 2009). Researchers have revealed a trade-off between H2ICE power output and NOx emission reduction applications such as those listed above (White et al. 2006). Notably, a nearly tenfold decrease in NOx emissions over those occurring from gasoline combustion was observed for an SI H2ICE (Kahraman et al. 2007). In comparison to diesel NOx emissions, H2ICE emis- sions from a direct injection CI engine were 20 percent lower than the same engine fueled with conventional diesel (Gomes-Antunes et al. 2009). When used as a fuel additive to CNG, HC, CO, and CO2 emissions decreased with increasing percentage of hydrogen blended with the fuel. NOx emissions increased over those reported for CNG combustion alone but were shown to be corrected using a catalytic converter, EGR, or lean burn techniques (Akansu et al. 2004, Bysveen 2007). PM emissions in the smaller size ranges have been shown to decrease by 85 percent when hydrogen is blended with gasoline (90 percent gasoline, 10 percent hydrogen) in a direct injection engine, only at the expense of forming greater levels of particles in the size range conducive to accumulation. By mass, the overall concentration of PM in the exhaust decreased by 17 percent (Zhao et al. 2010). Importantly, little data have been generated on the topic of HAPs resulting from the use of hydrogen-fueled vehicles. However, based on observed data for HC emissions, it can be expected that few HAPs are emitted due to combustion processes, and any HAP emissions would be tied to either combustion of the engine lubrication oils and/or the characteristics of fuels with which hydrogen may be blended (i.e., CNG or diesel). Hybrid Electric. The properties of HEVs depend largely upon the characteristics of the means by which electrical energy is supplied to the vehicle, as well as the type(s) of fossil fuel with which it is hybridized. Hence, it is difficult to provide focused discussion on operational and emission considerations with respect to GSE applications. Emission reduction potentials and penalties for HEVs are underpinned by the degree to which the vehicle is electrified and by what means, the source of the electrical energy used to power the vehicle, and the fuel(s) with which it is hybridized. Oxygenated Fuels (i.e., Ethanol, Dimethyl Ether) Oxygenated fuels contain a significant amount of oxygen in their chemical composition, which typically results in higher fuel combustion efficiency. Due to their volatile nature, oxygen- ated fuels are seldom used singly but are instead blended with conventional fuels. This subsection presents information on the oxygenated fuels ethanol and dimethyl ether. Ethanol. Ethanol mixed with a small portion of water (i.e., hydrous ethanol) has been uti- lized as an alternative fuel additive to methyl tert-butyl ether (MTBE), a known air toxic, in many on-road motor vehicles as a means of increasing the combustion efficiency of conventional fuels such as gasoline. When blended with conventional diesel fuel in a CI engine, ethanol has been shown to reduce CO and PM emissions but was shown to increase NOx emissions. However, in contrast, other studies have shown that operating load has a large impact on this trend, showing opposite emissions trends for CO, HC, and NOx than those identified above. In SI gasoline engines, significant CO and HC emission reductions (up to 90 percent) were observed in gasoline-ethanol blended fuels, at the expense of increased CO2 emissions due to higher combustion efficiency (up to 25 percent). NOx emissions were found to be largely dependent on the engine operating conditions and chemical balance of the fuel. HAP emissions of carbonyl compounds such as formaldehyde and acetaldehyde increase when ethanol is blended into both gasoline and diesel fuels, and tend to increase in concentra- tion with increasing engine speed.

50 airport Ground Support equipment (GSe): emission reduction Strategies, Inventory, and tutorial Dimethyl Ether. Dimethyl ether (DME) is a highly oxygenated fuel that is currently being studied for applications as primary fuel in ICEs, as well as an additive to improve the emission parameters of conventional fuels such as diesel (Acroumanis et al. 2008). Barring application of EGR, injection retardation, or exhaust after-treatments, DME emissions of NOx are found to be comparable to diesel emissions, but can be reduced to levels lower than diesel when using the above-referenced applications (Acroumanis et al. 2008). When blended with conventional diesel fuels, NOx emissions were reduced in the DME blends. However, HC and CO emissions measured higher with the DME blends than with diesel alone, but CO2 emis- sions from DME blends measured equal to or lower than diesel (Ying et al. 2006). Because DME is highly oxygenated and contains fewer single carbon-to-carbon bonds com- pared to traditional fuels such as diesel and gasoline, the potential for PM formation to occur due to its combustion is greatly reduced (Sidhu et al. 2001). Emissions of HAPs from combusted DME approximate those of other oxygenated fuels such as CNG and are comprised of benzene, toluene, ethylbenzene, styrene, benzaldehyde, naphthalene, acenaphthene, benzofluoranthene, benzo(e)pyrene, and indeno(1,2,3-c,d)pyrene (Sidhu et al. 2001). 3.4.3 Environmental Considerations and Challenges with Other Environmental Media Potential impacts of alternative-fuel utilization on areas of environmental concern other than air quality, including those related to water resources, soils, odor, and human health, are pre- sented in this subsection. Climatic effects on the feasibility of usage with respect to these alterna- tive fuels are also addressed, where applicable. Biodiesel Soil and Water Resources. Biodiesel fuel biodegrades up to four times faster than conven- tional petroleum diesel fuel. If leaked or spilled into the environment, biodiesel does not present the same level of soil, surface water, and groundwater contamination concerns typically associ- ated with gasoline and diesel fuels, making it ideal for use in environmentally sensitive areas such as wetlands, marine environments, and national parks. Human Health and Environmental Safety. The flashpoint for biodiesel is higher than 300°F (150°C), compared with about 125°F (52°C) for petroleum diesel, making biodiesel rela- tively safe for workers to handle, store, and transport. Recently, the U.S. Department of Labor Mining Safety Health Administration (MSHA) has implemented rules for underground mines that limit workers’ exposure to diesel PM. However, MSHA found that switching from petroleum diesel fuels to high blend levels of biodiesel (B50 to B100) significantly reduced PM emissions from underground diesel vehicles and substantially reduced workers’ exposure. Pure biodiesel can be extinguished with dry chemical, foam, halon, CO2, or water spray, although the water stream may splash the burning liquid and spread fire. Oil-soaked rags used in association with biodiesel can cause spontaneous combustion if they are not handled properly. Before disposal, rags should be washed with soap and water and dried in well-ventilated areas. Because biodiesel will burn if ignited, it must be kept separate from oxidizing agents, exces- sive heat, and ignition sources. No placards or warning signs are required for the transport of pure biodiesel. However, biodiesel blends with diesel and kerosene are required to be trans- ported in placarded trucks if the flash point of the blend is lower than 200°F (93°C), according to U.S. DOT regulations. If the flash point is lower than 140°F (60°C), the liquid is considered flammable and the Hazard Class 3 flammable placard is required. Local fire regulations deter- mine the requirements for signage on storage containers, but typically, tanks containing fuels (including B100) must be labeled with National Fire Protection Association diamonds. The

research Findings and products 51 National Fire Protection Association diamonds will indicate whether the fuel is flammable or combustible. Odor. Biodiesel is non-toxic and has a mild, somewhat pleasant odor. When burned, the fuel emits a fried-food or barbecue odor. Climatic Considerations. Biodiesel is the more susceptible to the cold than many other alternative fuels due to “gelling.” The most effective way to winterize biodiesel fuel is to blend it with petroleum diesel. Anti-gel additives chemically alter the fuel to inhibit the formation of wax crystals, but some reportedly work more effectively than others. The actual source of biodiesel will change its cold weather performance as well. For example, palm oil biodiesel will gel at very high temperatures, whereas algae- or camelina-derived biodiesel will gel at lower temperatures making them more appropriate for cold weather use. B20 blends are used mostly in very cold climates, such as northern Minnesota and Wyoming, where temperatures routinely fall below -30°F (1°C) in the winter. B20 has also been used for several years in the Boston Logan International Airport shuttle fleet with no winter problems. Other users have reported using B100 in extremely cold climates, such as in Yellowstone National Park. There the vehicles are equipped with winterization packages, and no other precautions were noted. Another cold climate option is heating the fuel or the engine. Heated fuel filters are available that run off an engine battery or can be plugged into a standard outlet. There are also heating pads and heating probes that can be applied to the fuel tank, again running off a 12-volt battery or standard current. An electric block heater (a heating element that is installed in the engine block and immersed in the coolant) is another solution. Block heaters warm the entire engine to ease starting. They typically operate on standard current and can remain plugged in for hours or overnight during bitterly cold conditions. Compressed Natural Gas Soil and Water Resources. Natural gas is relatively non-toxic, non-corrosive, and non- carcinogenic. It is also lighter than air, which results in the gas dissipating quickly in the event of a leak. Thus, accidental discharges of natural gas will not contaminate soil and water like spills of gasoline and diesel. In addition, the risk of uncontrolled combustion is reduced because of the higher flash point of natural gas compared to other petroleum fuels. Odor. Raw natural gas is odorless, so a distinctive odorant is added prior to distribution. This strong odor makes the presence of a leak very easy to detect. Climatic Considerations. With no major climatic drawbacks, CNG is among the best performing cold weather alternative fuels. Liquefied Petroleum Gas Soil and Water Resources. Propane is an approved “clean fuel” listed in the federal CAA and the Energy Policy Act. It is non-toxic and vaporizes at ambient temperatures. Because of these properties, the placement of propane tanks either above or below ground is not regulated by the U.S. EPA. Odor. As propane is virtually odorless and colorless in its natural state, a commercial odor- ant, ethyl mercaptan, is added to the gas. Climatic Considerations. Cold temperatures reduce the vapor pressure of propane. How- ever, there are no reported problems with its ignition in cold weather.

52 airport Ground Support equipment (GSe): emission reduction Strategies, Inventory, and tutorial Electricity Soil and Water Resources. Electric vehicles themselves present no direct threat to surface water, groundwater, and soils. However, battery disposal is a potential risk and tightly controlled by hazardous waste regulatory requirements. Moreover, the battery recycling and reuse market is rapidly expanding, as it did for lead-acid batteries in the past. Lithium batteries are more dif- ficult to dispose of, but procedures for recycling exist and are becoming more cost effective. The components of nickel-metal hydride batteries used in most electric drive vehicles are also recy- clable, but the necessary infrastructure is still limited. Owners of equipment that uses batteries containing sulfuric acid and/or lead must comply with annual chemical reporting requirements under the regulations of the U.S. EPA Superfund Amendments and Reauthorization Act of 1986 (aka Emergency Planning and Community Right-to-Know Act). Human Health and Environmental Safety. With respect to health and safety, electric drive vehicles must meet the same safety standards required for conventional-fuel vehicles sold in the United States. The exceptions are non-road vehicles, which are subject to less-stringent standards because they are typically limited to non-public roadways. Most electric vehicles are designed with safety features that deactivate the electric system in the event of an accident. For example, many are designed with cutoff switches to isolate the battery and disable the electric system, and all high-voltage power lines are colored orange for identification. In addition, EVs tend to have a lower center of gravity than conventional vehicles, making them less likely to roll over. Odor. Electric engines produce no odor with the exception of an “ozone” smell in rare circumstances. Climatic Considerations. As discussed previously, battery performance is adversely affected by cold, especially those of the lead-acid variety. Common remedies include battery insulation, a block heating system, or installation of an oversize starting battery. New battery technologies promise to improve on the cold weather problem. Hydrogen Soil and Water Resources. Hydrogen is a very small molecule with low viscosity and is therefore prone to leakage. However, it is considerably lighter than gasoline vapor and air and therefore disperses quickly into the atmosphere. As a result, it does not represent a significant source of soil or water contamination. Human Health and Environmental Safety. Hydrogen is non-toxic and non-poisonous; however, in a confined space, leaking hydrogen can accumulate and reach flammable concentra- tions. It is also an asphyxiant in sufficient concentrations. In a closed environment, leaks of any size are a concern, since hydrogen cannot be easily detected. Proper ventilation and the use of detection sensors can mitigate these hazards. Hydrogen gas is compressed and stored at high pressures. For safety, hydrogen tanks are equipped with pressure relief devices. As a liquid, hydrogen is stored at -423°F, a temperature that can cause cryogenic burns or lung damage. Detection sensors and personal protective equipment are critical when dealing with a potential liquid hydrogen leak or spill. Odor. Hydrogen is odorless. However, odorants are not used because there are no known odorants light enough to “travel with” hydrogen at the same dispersion rate. Current odorants also contaminate fuel cells, which are an important application for hydrogen.

research Findings and products 53 Climatic Considerations. Because a singular design for hydrogen-powered engines has not yet been selected and cold weather performance varies by design and application, the climatic effects are not known. Ideal hydrogen fuel cells produce only water vapor as a byproduct. There- fore, fuel cells run the risk of freezing in the cold. Hybrid Electric Many environmental properties of electric vehicles apply to hybrid electric vehicles, especially with respect to battery replacement and operation in cold weather climates. Refer to the subsec- tion on electricity for this information. Ethanol Soil and Water Resources. Ethanol is biodegradable and, if spilled, poses much less of a threat than petroleum to surface water, groundwater, and soils. Human Health and Environmental Safety. Ethanol (E85) is poisonous and flammable, should never be confused with beverage alcohol, and should be kept from open ignition sources. Fuel vapors can travel along the ground or be moved by ventilation and ignited by sources such as pilot lights, sparks, electric motors, static discharge, and other ignition sources at locations distant from material handling. In general, the same safety standards that apply to gasoline apply to E85. Odor. Ethanol exhibits a distinctly unpleasant (i.e., pungent) odor. Climatic Considerations. In cold weather climates, high ethanol blends present a problem to achieve enough vapor pressure for the fuel to evaporate and spark the ignition. However, E85 is considered to be the maximum blend to help mitigate this problem. At places where temperatures consistently fall below 10°F (-12°C), it is recommended that an engine heater system be installed. 3.5 GSE Tutorial To provide GSE stakeholders with the necessary information, data, and supporting materials to better understand, manage, and achieve meaningful reductions in GSE emissions, the relevant outcomes of this research are consolidated into a GSE Tutorial. Provided on the accompany- ing CD, this tutorial is a user-friendly, interactive, and self-paced tool for learning more about GSE and their functions and alternative fuels and their emission reduction potentials. Users can “point and click” their way through convenient, easy-to-follow synopses of the materials in a fashion that will help the user synthesize and apply the knowledge to real-world practice. To this end, the tutorial is structured in three modules, briefly summarized as follows: • Module 101, GSE Basics: Topics covered in this module include the types and functions of GSE, usage considerations, potential alternative fuels that could be used in GSE to reduce air quality impacts of their operation, environmental regulations and programs that pertain to GSE ownership and operation, and a primer of air quality science and policy principles. • Module 201, Emissions Reduction Approaches and Case Studies: Building on Module 101, this module addresses emissions reduction approaches applicable to GSE, including infrastructure improvements, vehicle retrofitting, alternative-fuel usage, and operation/ maintenance strategies. Additionally, airport and airline case studies on the topics covered in this module are also presented. • Module 301, Converting to Cleaner GSE: The intent of this module is to present the “big pic- ture” of GSE ownership and environmental impact mitigation strategies related to their use. The module summarizes the economic costs and environmental trade-offs of using cleaner GSE

54 airport Ground Support equipment (GSe): emission reduction Strategies, Inventory, and tutorial (where available), lists available vendors and distributors of both conventional- and alterna- tive-fuel GSE, and presents life-cycle (i.e., “well to wheels”) considerations that GSE owners and operators should keep in mind during their decision-making processes. 3.6 GSE Inventory The estimate of the nationwide GSE inventory was developed under Task 7 using data col- lected from three general sources: • Field surveys of selected airports were conducted to get a hands-on count of the number of GSE that could be found at large-hub, medium-hub, small-hub, and non-hub airports in varying climate conditions with potentially different equipment requirements. Correlations between the GSE inventories at these airports with several parameters were evaluated. The best fit correlations for total GSE and for individual GSE types were selected and applied to a list of airports to estimate the national GSE inventory. • GSE data provided by participating airlines were aggregated and estimates of the national inven- tory were made based on commercial aircraft operations. Comparison of the national inventory with this approach is made to the national inventory determined from the field survey correla- tions and is used to provide some idea of the uncertainty in the national GSE inventory estimates. • Finally, several GSE inventories that had been developed previously for individual airports were obtained and subjected to the correlations developed from the field surveys. The results of this comparison are also used to provide context regarding the uncertainty of the national GSE inventory estimates. 3.6.1 Airport Field Surveys and Data Evaluation Survey Methods and Results The research team contacted a number of airports to identify those that were interested in participating in this project by allowing team members to conduct field surveys of airport GSE. The final selection of airports was made to include large-hub, medium-hub, small-hub, and non-hub airports in warm and cold weather areas. The 12 surveyed airports and their survey dates are listed in Table 3-13. The first airport surveyed was Dallas-Fort Worth (DFW). Because of its size and level of activ- ity, a detailed DFW GSE Survey Plan was developed and used in most of the subsequent surveys. For most medium-hub and large-hub airports, the field surveys were coordinated with the air- port staff and, at the larger airports, took place during low-activity periods. These low-activity periods were either in the late-night/early-morning hours or later in the morning after the first flights of the day had departed. The surveyors attempted to collect the GSE type, make and model, fuel type, and year of manufacture for each piece of equipment. Initially, the horsepower was also one of the intended data elements to be collected. However, most GSE surveyed did not have engine power readily displayed, so this element was not collected on most equipment. The field teams recorded survey information on field logs and then transcribed the logs to electronic files (e.g., Microsoft® Word and Excel files). These data were also later reviewed by the field and the statistical teams, and several necessary modifications were made to facilitate the statistical evaluation. Table 3-14 provides the total GSE counts that were aggregated to create the field survey GSE database for all airports surveyed. The summary of the aggregated data by GSE type is provided in Table 3-15. Initially, the teams were identifying approximately 30 GSE types during the surveys. However, to facilitate

Airport Size Categorya Weather Categoryb Dates Surveyed (2011) Boise (BOI) Small Hub Cold July 26 Boston Logan (BOS) Large Hub Cold July 28 Dallas-Ft Worth (DFW) Large Hub Warm May 23 & 24 Detroit Wayne County (DTW) Large Hub Cold July 27 & 28 Fresno-Yosemite (FAT) Small Hub Warm July 12 Front Range (FTG) Non-Hub Cold May 3 Manchester (MHT) Medium Hub Cold July 28 Minneapolis-St. Paul (MSP) Large Hub Cold June 23 Sacramento International (SMF) Medium Hub Warm July 13 Seattle-Tacoma (SEA) Large Hub Warm June 21 Tampa Bay (TPA) Large Hub Warm August 26 Tucson International (TUS) Medium Hub Warm June 14 a 2010 size designations from FAA. b Airports were designated warm or cold based on the number of days with temperatures below 32°F (i.e., < 50 days = warm). Table 3-13. Airports surveyed for GSE. Table 3-14. GSE count by airport. Airport No. of GSE Boise (BOI) 321 Boston Logan (BOS) 1,704 Dallas-Ft Worth (DFW) 2,323 Detroit Wayne County (DTW) 890 Fresno-Yosemite (FAT) 124 Front Range (FTG) 48 Manchester (MHT) 235 Minneapolis-St. Paul (MSP) 1,952 Sacramento International (SMF) 513 Seattle-Tacoma (SEA) 1,026 Tampa Bay (TPA) 734 Tucson International (TUS) 155 Total Surveyed GSE 10,025 GSE Type No. of GSE Percentage of Fleet Air Conditioners/Heaters 312 3.1% Air Start Units 160 1.6% Aircraft Tractors/Tugs 705 7.0% Belt Loaders 1,102 11.0% Baggage Tugs 2,575 25.7% Buses 69 0.7% Cars/Pickups/Vans/SUVs 1,132 11.3% Carts 330 3.3% Cargo Loaders 281 2.8% Cabin Service/Catering Trucks 320 3.2% Deicing Trucks 399 4.0% Forklifts 314 3.1% Fuel Trucks 151 1.5% Ground Power Units/Generators/GPU-ACs 487 4.9% Hydrant Carts/Hydrant Trucks 62 0.6% Lavatory Carts/Lavatory Trucks 177 1.8% Light Carts 111 1.1% Lifts 344 3.4% Maintenance Trucks 56 0.6% Other 843 8.4% Passenger Stairs 95 0.9% Total 10,025 100.0% Table 3-15. GSE counts by GSE type.

56 airport Ground Support equipment (GSe): emission reduction Strategies, Inventory, and tutorial the statistical evaluation, several type categories were combined to provide a sufficient number of data points in a category to develop meaningful evaluations. Finally, the GSE type data differentiated by fuel type is summarized in Table 3-16. The field survey teams occasionally had difficulty determining the fuel type for some equipment. Filler caps for some equipment may have been located under a hood or otherwise covered, thus not visible during the survey. In some cases, the participating airport or an airport tenant provided data on equipment that did not include fuel type, and the equipment was not physically observed during the survey. This resulted in a moderate amount (almost 15 percent) of unknown fuel type counts in the field survey inventory. During the surveys, diesel fuel types were simply identified by the color or labels on the filler cap. The team was not able to determine whether the diesel was strictly petroleum based or bio- diesel. Diesel that is 85 percent to 100 percent biodiesel (B85-B100) is defined as an alternative fuel under DOE EPAct guidelines and is potentially eligible for grant funding under FAA’s VALE Program (see Section 3.2.6 of this report). Therefore, note that the ratio of alternative fuels to conventional fuels (petroleum diesel and gasoline) will be understated in this report. The distribution of GSE fuel types by airport—after unknown fuel types were removed and the fuel type distributions recalculated—is summarized in Figure 3-5. The use of alternative fuels (electric, propane, natural gas, and solar) range from 1 percent to 34 percent for the air- ports surveyed, with electric motors/battery power being the most prevalent of alternative-fuel equipment. GSE Type Total Fuel Type Percentage by GSE Type Diesel a Electric Gasoline LPG NG Solar Unk b Baggage Tugs/Cargo Tugs 2,575 15.4% 16.7% 52.7% 2.8% 0.0% 0.0% 12.3% Cars/Pickups/SUVs/Vans 1,132 4.9% 0.5% 83.9% 0.1% 0.1% 0.0% 10.5% Belt Loaders 1,102 25.0% 14.7% 44.6% 0.5% 0.4% 0.0% 14.8% Other 843 52.2% 4.0% 28.4% 1.5% 0.2% 0.0% 13.6% Aircraft Tractors/Tugs 705 67.7% 11.1% 8.2% 0.0% 0.0% 0.0% 13.0% Generators/GPUs/GPU-ACs 487 61.0% 9.9% 7.2% 0.0% 0.2% 0.0% 21.8% Deicing Trucks 399 64.7% 0.8% 26.6% 0.0% 0.0% 0.0% 8.0% Lifts 344 21.8% 26.2% 26.7% 5.5% 0.0% 0.0% 19.8% Carts 330 1.2% 77.6% 5.5% 0.9% 0.0% 0.0% 14.8% Cabin Service/Catering Trucks 320 52.2% 0.3% 15.3% 0.0% 0.0% 0.0% 32.2% Forklifts 314 12.7% 8.6% 13.7% 44.9% 0.0% 0.0% 20.1% Air Conditioners/Heaters 312 76.3% 2.6% 11.5% 0.0% 0.0% 0.0% 9.6% Cargo Loaders 281 78.6% 0.4% 7.5% 0.4% 0.0% 0.0% 13.2% Lavatory Trucks/Lavatory Carts 177 17.5% 7.9% 59.9% 0.0% 0.6% 0.0% 14.1% Air Start Units 160 71.9% 0.6% 2.5% 0.0% 0.0% 0.0% 25.0% Fuel Trucks 151 64.9% 2.0% 8.6% 0.0% 0.0% 0.0% 24.5% Light Carts/Light Stands 111 64.9% 1.8% 7.2% 0.0% 0.0% 9.0% 17.1% Passenger Stairs 95 31.6% 1.1% 42.1% 1.1% 0.0% 0.0% 24.2% Buses 69 21.7% 0.0% 7.2% 0.0% 55.1% 0.0% 15.9% Hydrant Carts/Hydrant Trucks 62 61.3% 0.0% 22.6% 0.0% 0.0% 0.0% 16.1% Maintenance Trucks 56 28.6% 0.0% 44.6% 0.0% 0.0% 0.0% 26.8% Surveyed GSE Average 10,025 33.5% 11.6% 37.0% 2.6% 0.5% 0.1% 14.7% a Diesel fuel types were simply identified by the color or labels on the filler cap. The research team was not able to determine whether the diesel was strictly petroleum based or biodiesel. Diesel that is 85 percent to 100 percent biodiesel (B85-B100) is defined as an alternative fuel under DOE EPAct guidelines and is potentially eligible for grant funding under FAA’s VALE Program (see Section 3.2.6 of this report). Therefore, note that the ratio of alternative fuels to conventional fuels (petroleum diesel and gasoline) will be understated in this table. b Unk = Unknown, unable to determine during survey . Table 3-16. GSE counts by type and fuel.

research Findings and products 57 The distribution of fuel types by airport shown on Figure 3-5 indicates that only three of the surveyed airports had more than 20 percent alternative fuels. Comparing the air quality nonat- tainment designations for the surveyed airports indicates that regions around the Dallas-Fort Worth (DFW), Fresno-Yosemite (FAT), and Sacramento (SMF) airports may have the worse air quality of the 12 surveyed airports. The region around DFW is classified as serious for ozone (smog) nonattainment; the region around FAT is classified as extreme (worst classification) for ozone and nonattainment for particulate matter (PM2.5); and the region around SMF is classi- fied as severe for ozone nonattainment and nonattainment for particulate matter (both PM2.5 and PM10). Only three other surveyed airports are in ozone nonattainment areas, and the clas- sification for ozone in these areas is marginal or moderate. Regulations impacting mobile source emissions in the Dallas-Fort Worth, Fresno, and Sacramento areas may have influenced the con- version or selection of alternative-fuel equipment. Statistical Analysis Using the GSE inventories from the surveyed airports, a number of potential correlations between the GSE counts and airport activity and climate parameters were evaluated. The major parameters included total operations, commercial operations, and enplaned passengers, as well as several metrics to represent the effect of cold climates. Regarding the weather parameters, the researchers had obtained anecdotal information indicating that more GSE were needed in cold weather airports due to the impact of this type of weather on the operation and maintenance of equipment (i.e., the equipment required more time for repair and maintenance; thus, more equipment was needed to service flights). Figure 3-5. GSE fuel type distribution by surveyed airport.

58 airport Ground Support equipment (GSe): emission reduction Strategies, Inventory, and tutorial The GSE inventories for the 12 surveyed airports are plotted against 20101 commercial opera- tions on Figure 3-6. From this plot it can be seen that the relative number of GSE at the Detroit Metropolitan Wayne County Airport (DTW) per aircraft operation were substantially lower than the other airports. This was likely due to severe weather that occurred during the survey, closing down the airport for most of the survey period. Therefore, the DTW inventory was not used in the correlations developed below. A series of equations were then analyzed with the total GSE counts to determine which of them provided reasonable results in terms of correlation coefficients and percent differences from measured counts. From this series, six equations that provided the best fits were analyzed for total GSE and for each GSE type category: Eq. 2: P1 × Total Enplanements (in millions) Eq. 6: P1 × Commercial Operations (in millions) Eq. 7: P1 × Total Enplanements (in millions) + P2 × Commercial Operations (in millions) Eq. 8: P1 × Commercial Operations (in millions) + P2 × Climate Code × Total Operations (in millions) Eq. 13: P1 × Commercial Operations (in millions) + P2 × Climate Code × Commercial Oper- ations (in millions) Eq. 22: P1 × Commercial Operations (in millions) + P2 × Temperature Parameter The P1 and P2 values are best fit constants determined statistically; the Climate Code is a value of 1 for cold airports2 and a value of 0 for warm airports; and the Temperature Parameter is the 500 1,000 1,500 2,000 2,500 100,000 200,000 300,000 400,000 500,000 600,000 700,000 N um be ro fG SE 2010 Commercial Operations All Surveyed Airports DTW Figure 3-6. Number of GSE versus 2010 commercial operations by airport. 1The 2010 airport operations databases were the most current databases available when this evaluation was being conducted. It was assumed that the GSE fleet information collected in 2011 would be fairly representative of the fleet in 2010. 2The definition of a cold airport was one where temperatures dropped below 32°F (based on National Oceanic and Atmospheric Administration databases) on 50 days or more annually; all other airports were defined as warm.

research Findings and products 59 average temperature in January for the given airport. It should be noted that Total Enplanements, Commercial Operations, and Total Operations are not completely independent parameters. The Climate Code and Temperature Parameter are independent parameters from the others. There- fore, only Equation 22 analyzes the correlation with two independent parameters, Equations 2 and 6 analyze the correlations with one parameter, and the remaining equations analyze the correlations with a hybrid set of parameters. These equations were initially applied to the aggregate GSE total at each airport and then applied to the individual GSE categories at each airport. The following list presents the assump- tions used to develop the linear correlations: • GSE inventories from 12 airports (BOI, BOS, DFW, DTW, FAT, FTG, MHT, MSP, SEA, SMF, TPA, and TUS) were reviewed, and the inventory from DTW was dropped from further evalu- ation since it was undercounted due to severe weather during the survey. • The linear, least squares regressions were performed with SYSTAT v.13 software. • One to three airport activity and/or climate parameters were used in the initial screening equations. • After the initial screening of potential regression equations, the equations selected for final comparisons would be those with no more than two parameters. • All regression lines would go through the origin (0,0) meaning that no activity would cor- respond with no GSE. • Final selection of the best fit equation for each type of GSE was determined by the researchers after they reviewed the coefficient of determination (R2 value) and percent differences. Table 3-17 presents the statistically determined P1, P2, and R2 values, as well as the percent differences from the surveyed inventory, for each of the six best fit equations listed previously. The comparison of the calculated total GSE for each of the 11 airports used from the field survey with the actual survey results is shown on Figure 3-7. When the individual GSE types were analyzed, the best fit equation was either Equation 7 or Equation 8. The best fit coefficients (P1 and P2) for the selected equation for each GSE type, as well as the coefficient of determination and percent difference from the surveyed inventories, are presented in Table 3-18. National GSE Inventory Estimate Once the best fit equation and parameters were determined for each GSE type, the selected equations were applied to over 500 U.S. airports, which represent approximately 99 percent of the commercial operations nationwide in 2010. Since the fit equations were linear, sums of the parameter quantities (i.e., Total Enplanements, Commercial Operations, and Climate Code Total Operations) over all 500+ airports were used to calculate national GSE inventories by GSE type. The enplanements and operations data were obtained from the Operations Network (OPSNET), Air Traffic Activity Data System (ATADS), Enhanced Traffic Management System Counts (ETMSC), and Terminal Area Forecast (TAF) databases maintained by the FAA. The estimated national inventory of GSE by type is presented in Table 3-19. Equation No. P1 P2 Correlation (R2) % Diff from Counted 2 93.4 NA 0.948 5.71% 6 4010 NA 0.978 3.38% 7 79.5 7350 0.985 3.12% 8 3600 1090 0.997 0.60% 13 3600 1160 0.996 2.09% 22 4040 0.469 0.978 4.18% Table 3-17. Best fit correlation constants for total GSE at 11 surveyed airports.

60 airport Ground Support equipment (GSe): emission reduction Strategies, Inventory, and tutorial 500 1,000 1,500 2,000 2,500 100,000 200,000 300,000 400,000 500,000 600,000 700,000 To ta lG SE In ve nt or y 2010 Commercial Operations Surveyed Inventory Estimated Inventory Figure 3-7. Comparison of estimated to surveyed GSE inventories. GSE Type Selected Equation P1 P2 Coefficient of Determination (R2) % Difference* Total GSE 8 3603 1086 0.997 0.6% Air Conditioners/Heaters 8 80.8 102 0.667 +15.8% Air Start Units 7 3.19 76.3 0.921 9.4% Aircraft Tractors/Tugs 8 231 108 0.980 +5.4% Belt Loaders 8 417 36.9 0.990 2.6% Baggage Tugs/Cargo Tugs 8 1182 84.5 0.978 +7.4% Buses 7 1.30 36.2 0.179 41.0% Cars/Pickups/Vans/SUVs 8 385 191 0.949 +4.6% Carts 8 115 65.1 0.757 +6.0% Cargo Loaders 7 1.90 26.4 0.897 8.4% Cabin Service/Catering Trucks 7 4.12 315 0.952 +9.8% Deicing Trucks 8 131 116 0.976 +18.6% Fork Lifts 7 7.60 453 0.932 +1.5% Fuel Trucks 8 45.2 17.6 0.813 11.8% Generators/GPUs/GPU-ACs 7 4.58 24.9 0.823 19.0% Hydrant Trucks/Hydrant Carts 7 2.10 115 0.654 1.7% Lavatory Trucks/Lavatory Carts 7 0.376 51.8 0.960 5.9% Light Carts/Light Stands 7 1.33 21.4 0.730 24.1% Lifts 8 93.4 119 0.935 +19.5% Maintenance Trucks 8 10.6 15.9 0.424 +10.3% Other 8 166 290 0.670 7.0% Passenger Stairs 8 22.0 25.0 0.667 7.1% * % Difference = 100% × (Calculated GSE – Inventoried GSE)/Inventoried GSE. Table 3-18. Best fit equations for total GSE and individual GSE types at 11 airports.

research Findings and products 61 3.6.2 Airline-Provided Data The research team contacted U.S. air carriers and other owners of GSE, primarily through contacts within Airlines for America (A4A, formerly the Air Transport Association). GSE data sets for seven individual airlines were provided. The data sets collected from these carriers were used to analyze the aggregated GSE fleet mix and to develop a second estimate of the nationwide GSE inventory for the purpose of providing some context on the uncertainty of the estimated national inventory developed from the field survey data. GSE Fleet Mix Summaries These data were aggregated and are summarized by GSE type in Table 3-20. The airline- provided fleet mix of GSE types is also compared to the mix obtained from the 12-airport field survey (see Table 3-14). Both field survey and airline-provided data indicate that over 25 percent of the GSE fleet is in the baggage tugs/cargo tugs category, roughly twice as much as the next highest GSE type. The top six GSE types for airline-provided inventories include baggage tugs/cargo tugs, belt loaders, cars/pickups/vans/SUVs, aircraft tractors/tugs, other (e.g., runway maintenance, snow removal, grounds maintenance, and miscellaneous equipment), and carts. The top six types from the surveyed airports include baggage tugs/cargo tugs, cars/pickups/vans/SUVs, belt loaders, other, aircraft tractors/tugs, and generators/GPUs/GPU-ACs. While there is some variation in the order of the categories between the two data sets, the top six categories represent approximately 68 percent, or two-thirds, of the aggregated GSE fleet in both data sets. GSE Type Calculated National Number of GSE Percentage of Fleet Baggage Tugs/Cargo Tugs 25,367 23.6% Cars/Pickups/Vans/SUVs 13,361 12.4% Other 10,566 9.8% Belt Loaders 10,494 9.7% Aircraft Tractor/Tugs 7,857 7.3% Deicing Trucks 5,732 5.3% Fork Lifts 5,078 4.7% Lifts 4,917 4.6% Cabin Service/Catering Trucks 4,373 4.1% Air Conditioners/Heaters 4,238 3.9% Carts 4,168 3.9% Generators/GPUs/GPU-ACs 2,679 2.5% Cargo Loaders 1,963 1.8% Lavatory Trucks/Lavatory Carts 1,465 1.4% Fuel Trucks 1,454 1.4% Hydrant Trucks/Hydrant Carts 1,181 1.1% Passenger Stairs 1,089 1.0% Maintenance Trucks 616 0.6% Air Start Units 500 0.5% Light Carts/Light Stands 454 0.4% Buses 86 0.1% Totals 108,578a 100.0%b a Value shown for total GSE was determined by using Equation 8. If individual GSE type totals are summed, the total GSE value would be 107,636. Therefore, the difference between applying Equation 8 to total GSE and summing the individual GSE type totals is only about 1 percent. b The GSE type percentages are based on the sum of the individual types, or 107,636 total pieces of equipment. Table 3-19. Estimated national GSE inventory by GSE categories.

62 airport Ground Support equipment (GSe): emission reduction Strategies, Inventory, and tutorial The airline-provided data are also summarized by fuel type in Table 3-21. Included in this table is a comparison to the fuel type distribution from the 12-airport field survey (see Table 3-16). As noted in Section 3.6.1, fuel type for almost 15 percent of the equipment surveyed at the 12 airports was unknown. On the other hand, the airline-provided data usually included fuel type for each piece of equipment; only 0.5 percent of the aggregated airline-provided data set were unknown. Therefore, the airline-provided fuel data provide a reasonable fuel-type distri- bution for those airlines participating in the study. GSE Type From Airline-Provided Data Percent (& Rank) of GSE Fleet from Airport Surveys No. of GSE Percent (& Rank) of GSE Fleet Air Conditioners/Heaters 901 4.5% (8) 3.1% (12) Air Start Units 447 2.2% (14) 1.6% (15) Aircraft Tractors/Tugs 1,786 8.8% (4) 7.0% (5) Belt Loaders 2,632 13.0% (2) 11.0% (3) Baggage Tugs/Cargo Tugs 5,361 26.5% (1) 25.7% (1) Buses 65 0.3% (20) 0.7% (19) Cars/Pickups/Vans/SUVs 1,900 9.4% (3) 11.3% (2) Carts 1,028 5.1% (6) 3.3% (9) Cargo Loaders 198 1.0% (16) 2.8% (13) Cabin Service/Catering Trucks 492 2.4% (13) 3.2% (10) Deicing Trucks 635 3.1% (11) 4.0% (7) Forklifts 728 3.6% (10) 3.1% (11) Fuel Trucks 79 0.4% (18) 1.5% (16) Generators/GPUs/GPU-ACs 960 4.7% (7) 4.9% (6) Hydrant Trucks/Hydrant Carts – 0.0% (21) 0.6% (20) Lavatory Trucks/Lavatory Carts 588 2.9% (12) 1.8% (14) Light Carts/Light Stands 79 0.4% (19) 1.1% (17) Lifts 784 3.9% (9) 3.4% (8) Maintenance Trucks 95 0.5% (17) 0.6% (21) Other 1,204 6.0% (5) 8.4% (4) Passenger Stairs 260 1.3% (15) 0.9% (18) TOTAL 20,222 100.0% 100.0% a Counts shown are for GSE inventories provided by seven U.S. air carriers. Table 3-20. Airline-provideda GSE counts by GSE type. Fuel Type From Airline-Provided Data From Field Surveys (12 Airports) No. of GSE Percentage of GSE Fleet No. of GSE Percentage of GSE Fleet Gasoline 7,761 38.4% 3,712 37.0% Diesel 7,243 35.8% 3,359 33.5% Electric 4,306 21.3% 1,166 11.6% Propane/LPG 645 3.2% 257 2.6% Natural Gas 158 0.8% 48 0.5% Solar – 0.0% 10 0.1% Unknown 109 0.5% 1,473 14.7% Totals 20,222 100.0% 10,025 100.0% Table 3-21. GSE fuel type distributions.

research Findings and products 63 Comparing the fuel distributions from the two data sets does show some similarities. Specifi- cally, the ranking of fuel type is identical for both (ignoring the data in the “unknown” fuel-type category); from highest to lowest, the use is gasoline, diesel, electric, propane/LPG, natural gas, and solar. Gasoline and diesel account for over 70 percent of the fuel type distribution from all GSE in both data sets. The electric GSE mix in the airline-provided data is more than twice the electric GSE mix in the field survey data. Several reasons may contribute to this difference: the unknown fuel types for the field survey data, the regulatory environment where the airports were surveyed, and the policies of the airlines providing GSE information. Based on the field survey approach for determining fuel type (observation of filler cap colors or labels), the unknown fuel types in the surveyed data may include a larger proportion of elec- tric GSE because those units would not have fuel filler caps. However, some of the data obtained at several airports were provided by the airport operator or a tenant in the form of hardcopy printouts that did not include fuel type. The fuel type for equipment data collected in this man- ner is likely to be more similar to the known fuel-type distribution. As noted in Section 3.6.1, regulations may affect the conversion of GSE to alternative fuels; thus three of the airports surveyed have a larger portion of non-conventional-fuel GSE. The other airports are likely to see conversions to alternative fuels, but at a slower rate than those in non- attainment areas. Thus the surveyed data may be indicative of the fuel-type distribution nationally. Finally, only seven airlines are represented in the airline-provided GSE database. It is possible that the major contributors to these data sets have moved to more alternative fuels through eco- nomic analysis, policy decisions, and environmental constraints in key hubs. Overall, the field survey and airline inventories indicate that between roughly 15 to 25 percent of the national GSE fleet was powered by alternative fuels at the time of this evaluation. The most prevalent of these alternative-fuel GSE are electric equipment. Alternative National GSE Inventory Estimate The research team estimated a national GSE inventory using the airline-provided GSE counts. Since there appeared to be some difference in GSE count per operation by carrier category, the team chose to split the activity by major carrier and commuter airlines. The total operations by airline for 2010 were obtained from the Bureau of Transportation Statistics Research and Inno- vative Technology Administration. Specifically, the Air Carrier Statistics T-100 Segments data- base for all carriers was downloaded. The operations from domestic airports were determined for each of the seven airlines providing data, and then combined into two groups: major carriers (five airlines) and commuter carriers (two airlines). The total GSE inventory for each group was determined from the airline-provided data. Finally, the total commercial operations in the United States for over 500 airports were split into air carrier and commuter/air taxi components. Roughly, the airports database indicated that a total of 13 million commercial operations were by major carriers and a total of 10 million commercial operations were by commuter/air taxi carriers in the United States in 2010. The total GSE count for the major air carrier group was multiplied by the ratio of total major air carrier operations in the United States divided by the commercial operations for the five air carriers in the airline-provided GSE data sets. This calculation indicated that nationally, major air carriers could potentially account for 47,000 units of GSE. The total GSE count for the commuter carrier group was multiplied by the ratio of total air taxi operations in the United States divided by the commercial operations for the two commuter carriers in the airline-provided GSE data sets. This calculation indicated that nationally, com- muter carriers could potentially account for 27,000 units of GSE.

64 airport Ground Support equipment (GSe): emission reduction Strategies, Inventory, and tutorial Overall, the estimate of the national GSE inventory using this approach would be approxi- mately 74,000 units (47,000 plus 27,000). This result is substantially lower than the estimated inventory developed from airport survey data (~108,000). Several possible explanations for the apparent discrepancy are provided in the following paragraphs. Survey Sample Size. The airport field survey was conducted at airports that were selected to represent the national average. The commercial operations at these airports represented approxi- mately 10 percent of the national commercial operations in 2010. While a 10 percent sample population is not unreasonable for estimating the national inventory, the possibility does exist that the selected airports have substantially higher GSE counts than the national average. Equipment Ownership. In reviewing the airline-provided GSE data, the research team noted that the GSE owned per operation fluctuated between 1 and 6 total units of equipment per 1,000 commercial operations. The research team assumed that one or more of the airlines outsourced, at least partially, the ground handling activity. If so, the equipment would belong to the ground handler and would not be in the airline data sets. Also, equipment owned by the airports in the field survey database would not be included in the airline data sets. This situation would lead to an underestimate of the national GSE fleet when commercial operations are applied to the airline-provided data to scale up from the sample population data to the national inventory. The researchers reviewed the raw survey forms and determined that approximately 24 percent of the total GSE counted in the field survey was owned by fixed base operators (FBOs), ground handlers, or airport operators. Thus, the national inventory estimated from the airline-provided data could be adjusted upward by this percentage to account for non-airline-owned equipment. Making such an adjustment increases that inventory from approximately 74,000 to 92,000 units of equipment. Cold Weather Adjustment. The correlation developed from the survey data for total GSE (Equation 8) included an adjustment for cold weather airports that was not applied to the airline data. It was not possible to include a correction for cold weather effects to the airline-provided data, because some of the data provided did not include the airport where the equipment was located. However, the general effect of the adjustment term was to increase the effective opera- tions when calculating GSE, and applying the term provided an improvement in the correlation (increased the coefficient of determination to 0.992 from 0.951). Comparing the terms in Equa- tion 8 for the 500+ airports included in the national inventory, an adjustment of 20 percent was applied to the commercial operations overall to get to the estimated national inventory. Increasing the national GSE inventory estimated from the airline-provided data by 20 percent would result in an inventory of 100,000 units of GSE, within 8 percent of the national inventory estimated from the airport survey correlation. Therefore, the weather adjustment parameter in Equation 8 is at least partially responsible for the differences between the two national inventories. Potential Outlier Impact. The correlations developed from the field survey data were made with data from 11 of the 12 surveyed airports. As noted in Section 3.6.1, data from DTW was not included due to severe weather hampering data collection efforts during the survey. If these data were included in a correlation based on all 12 surveyed airports, a lower estimate of the national inventory would be determined, because the DTW data point is well below the approximate line between the other airports, as shown in Figure 3-6. However, it is the distance off of this line that indicates the DTW GSE count is an outlier, and the reason for the unusually low count is known. Therefore, the initial correlation developed from the 11 other airports is considered better for predicting the national inventory than a correlation developed with the DTW data. Potential Electric GSE Impact. Anecdotal evidence suggests that operators of electric GSE may need to provide additional units of equipment compared to combustion-driven equipment due to the charging time necessary for electric GSE. The equipment being charged is essentially

research Findings and products 65 unavailable, and operators need additional equipment to maintain service levels. The surveyed airports all had some quantity of electric GSE. The largest airport surveyed (DFW) had the high- est proportion of electric GSE, 26 percent of that airport’s fleet. Five other surveyed airports had between 13 and 24 percent electric GSE in their fleets. The average of the surveyed airports was approximately 12 percent electric. If this average value for the surveyed airports is above the national average for electric GSE, and if operators of electric GSE truly need additional equipment, then the national inventory developed from survey data may be overestimated. However, this con- clusion does not appear to be consistent with the airline-provided GSE data. The airline-provided data had more electric equipment in the aggregated fleet mix (21 percent), yet the estimate from this information provided a much lower national GSE inventory. It does not appear the differences between the two estimates can be explained by differences in the relative quantity of electric GSE. 3.6.3 Existing GSE Data Sets Finally, several GSE inventories that had been previously developed for individual airports were obtained and subjected to the correlation developed from the field surveys. The invento- ries used were for Los Angeles International Airport (2000 and 2006), Seattle-Tacoma Interna- tional Airport (2002), and the Houston Airport System (1996). Three airports are included in the Houston Airport System (HAS) inventory: George Bush Intercontinental Houston (IAH), Hobby (HOU), and Ellington Field (EFD). The comparison of the inventoried GSE with pre- dicted GSE counts are shown on Figure 3-8. Figure 3-8. GSE inventories for selected airports and years versus predicted values with 95% confidence intervals.

66 airport Ground Support equipment (GSe): emission reduction Strategies, Inventory, and tutorial This comparison indicates that the correlation has substantial errors when applied to individual airports. However, note that the total inventory for the airports in this comparison is 8,330 units of equipment, while the predicted total for the same airports is 8,169 units of equip- ment, an error of less than 2 percent. Therefore, the correlation is considered most appropriate for estimating the national GSE inventory, and possibly large regional inventories. However, using the correlation for individual airports is not recommended. 3.6.4 National GSE Inventory Recommendation The research team recommends that the national GSE inventory developed from the cor- relation based on data collected at 11 of the surveyed airports (see Section 3.6.1) be used as the best estimate for the time period of this evaluation. If the estimated inventory developed from airline-provided data is adjusted upward to account for both the non-airline-owned equipment and the cold weather factor, the adjusted inventory would be approximately 110,000 units, very close to the 108,600 value predicted from the survey data correlation. 3.7 Economic Factors Prepared in connection with Task 8, this element of the Working Plan was designed to pro- vide GSE owners and operators with practical information pertaining to (1) alternative fuels, (2) costs for infrastructure, (3) purchasing vs. retrofit costs, and (4) other qualitative consider- ations pertaining to operating GSE. For ease of understanding, this information is provided in the following subsections as responses to four questions pertaining to these topics. 3.7.1 Alternative Fuels What alternative fuels are appropriate and available for GSE equipment types? Section 3.4 provides a comprehensive assessment of the types of alternative fuels presently available for GSE and, therefore, the information is not repeated here. However, they include the following: • Mixtures containing 85 percent or greater ethanol (E85) • Mixtures containing 20 percent or greater biodiesel meeting ASTM D 6751 • Natural gas (compressed or liquefied) • Liquefied petroleum gas (propane) • Methanol • Hydrogen • Electricity Each of these fuel types are described in terms of their energy content, availability, costs, infrastructure requirements, and use with GSE. Among them, electric (i.e., battery), propane, and natural gas are presently the most commonly used. 3.7.2 Infrastructure What is the range of costs for infrastructure for each alternative-fuel type? The infrastructure requirements for alternative-fuel GSE, as well as their costs, are discussed in Section 3.4. This information addresses the primary needs of (1) fuel tanks and dispensing equipment for CNG and LPG GSE and (2) the electrical charging equipment for electric GSE.

research Findings and products 67 Over the past several years, the FAA VALE Program has financed a number of airport improvements aimed at supporting alternative-fuel GSE or reducing the need for conventional- fuel GSE. Table 3-22 contains a summary listing of several VALE projects designed to meet these objectives. As shown, the costs for the infrastructure varies widely based upon the type of project, the system capacity, and a wide array of supporting apparatus. For example, the costs for electric GSE recharging stations range from approximately $10,000 to $60,000 according to their size and quantity purchased. By comparison, PCA units, which eliminate the need for GPUs, range in costs from $50,000 to more than $100,000. 3.7.3 Purchasing versus Retrofit What are the relative costs for purchasing new equipment versus retrofitting existing GSE? The costs to purchase GSE are among the leading considerations among owners and opera- tors of the equipment when evaluating whether to invest in new, alternative-fuel models or to retrofit existing stock. This aspect of GSE ownership is particularly challenging in times of economic decline and airline mergers—given the significant capital costs required to operate a fleet of equipment. For clarity, capital costs are one-time expenditures incurred when new GSE is purchased. It is also because of these potentially significant capital expenditures that the purchase cost is difficult to obtain. For example, because most GSE are purchased in multiple units as opposed to individual procurements, the cost for each unit varies based on the size and make-up of the order. This is further compounded by the fact that neither GSE manufactur- ers nor the GSE purchasers are willing to reveal the details of their transaction for business reasons. These and several other variables that have an effect on the costs of purchasing GSE are addressed in Section 3.4.1. Airport Project Description Total Cost Cost Per Unit Cincinnati/ Northern Kentucky International Airport Installation of 16 PCA units $1,760,000 $110,000 Installation of 14 gate electrification units $854,000 $61,000 Electrical infrastructure upgrades $625,000 $625,000 Erie International Airport/Tom Ridge Field Installation of 2 PCA units (20-ton) $140,000 $70,000 Installation of 1 PCA unit (30-ton) $70,000 $70,000 Electrical infrastructure upgrades $90,000 $90,000 Gerald R. Ford International Airport Installation of 3 PCA units (30-ton) $232,264 $77,421 Installation of 2 PCA units (75-ton) $280,222 $140,111 Installation of 3 ground power units (90 kVA) $167,311 $55,770 Installation of 2 ground power units (140 kVA) $152,884 $76,442 Electrical infrastructure upgrades $177,183 $177,183 Installation of 6 PCA units (30-ton) $449,904 $74,984 Installation of 6 ground power units (400 Kz) $319,392 $53,232 Lehigh Valley International Airport Installation of 7 PCA units (30-ton) $872,780 $124,683 Installation of 1 PCA unit (45-ton) $148,860 $148,860 Electrical infrastructure upgrades $657,099 $657,099 Philadelphia International Airport Installation of 25 electric GSE rechargers $2,642,007 $105,680 Electrical infrastructure upgrade $5,843,640 $5,843,640 Seattle-Tacoma International Airport Installation of central PCA 48 gates (Phase I) $40,600,600 $845,833 Installation of central PCA 23 gates (Phase II) $4,816,905 $209,431 University Park Airport Electric vehicle recharger $10,327 $10,327 Table 3-22. Summary of VALE projects.

68 airport Ground Support equipment (GSe): emission reduction Strategies, Inventory, and tutorial Within the public domain of information, the Idaho National Laboratories GSE Cost-Benefit Analysis Study provides a representative and most up-to-date sample of the purchase costs for commonly used GSE. Broken out by three fuel types (i.e., gasoline, diesel, and electric), these “ballpark” costs are listed in Table 3-23. As shown, conventional-fuel (i.e., gasoline and diesel) baggage tractors and belt loaders range from $26,000 to $32,000 at the small end of the spectrum with the bigger aircraft pushback tugs at $86,000 and the much larger cargo loaders at $475,000. Where the data are available, diesel equipment generally costs 10 to 15 percent more than gasoline, and electric equipment gener- ally costs 10 to 25 percent more than diesel. Moreover, charging stations are additional costs for electric GSE that are not accounted for in the purchase costs. In some areas of the country, particularly those that are designated as nonattainment for the NAAQS, there is pressure on GSE owners and operators to convert conventional-fuel GSE to alternative-fuel technologies—often before the useful life of the original equipment is reached. In most cases, the gasoline/diesel engines are replaced with electric motors and batteries, and the body, chassis, and drive chain are retained. In the cases of natural gas or propane, the conversions are generally more compatible, and therefore less costly. As noted previously, purchase costs were difficult to obtain for both new equipment purchases and for retrofitting equipment. In most GSE types, the engine is likely the most expensive item in the GSE purchase price. The cost of converting existing GSE to operate on alternative-fuel engines may be comparable to replacing the engine on the existing gasoline or diesel GSE. Retrofitting costs may also be in the ballpark of purchasing a new GSE, especially if the retrofitting is done on an as-needed or piecemeal basis compared to large lot purchases of new equipment. 3.7.4 Qualitative Considerations What are the qualitative considerations an airline and airport must take into account concerning operating GSE? Among the range of qualitative factors that are deemed as potentially significant, the major- ity have already been identified and discussed in Section 3.4. Therefore, the following provides a synopsis of this material, supplemented with other relevant information, where appropriate. Safety Airlines and airports will both agree that among the leading considerations concerning the operation of GSE is that it must be safe to operate. For example, many GSE have various safety design features such as speed restriction mechanisms, safety mirrors, operator enclosures, safety Type Fuel Type Costs Ground Power Unit Diesel $17,000 Baggage Tractor Gasoline $26,000 Diesel $28,000 Electric $35,500 Belt Loader Gasoline $28,500 Diesel $32,200 Electric $38,800 Pushback Tug Diesel $86,200 Electric $93,000 Cargo Loader Diesel $475,000 Table 3-23. Ballpark GSE purchase costs.

research Findings and products 69 lights and markings, etc. To achieve equivalent levels of safety among various types of equipment, additional operator training and safety supervision is often required. The airline and airport also need to consider the safety of infrastructure that would be required for various types of GSE (e.g., operating electric GSE battery charging stations and risks associ- ated with water/weather, electric shock, electric overload, etc.). The airline and airport may classify safety as both a financial and non-financial consideration because of the additional training, insurance costs, and/or liability that may be associated with the operation of certain GSE. Environmental Airlines and airports have shown a renewed interest in business decisions that focus on envi- ronmental (i.e., “green”) initiatives. For example, many airlines and airports have corporate sus- tainability policies and/or guidance manuals that encourage or even require decision makers to consider environmental impacts. As such, airline and airport management are cognizant that their business decision may have an effect on the environment. Additionally, environmental cost implications could result from various types of fuel spills and/or accidents that could result in financial penalties, U.S. EPA visits, consulting costs, etc. Public Perception/Marketing The general public’s awareness and/or perception of an airline’s and/or an airport’s environ- mental responsibility may influence the decision to purchase and/or operate alternative-fuel GSE. Airline employees, stockholders, airport employees, customers, local businesses, and the residential community are increasingly aware of management decisions that could harm the environment. Additionally, the press is quick to acknowledge an airline or airport that chooses to operate alternative-fuel GSE instead of conventional-fuel GSE out of its own “goodwill.” Airlines and airports also have their own opportunity to self-promote their environmentally responsible decisions. Where competition for airlines or airports is prevalent, some customers may be less inclined to purchase a plane ticket from an airline/airport that has received negative press atten- tion for fuel spills and the operation of high-emitting GSE (for example) compared to an airline or airport that is perceived to be an environmental steward. Therefore, an airline or airport should recognize the value of public perception and marketing opportunities in its decision to operate GSE. Understanding the attitude of the government and the business community toward the envi- ronmental stewardship of an airline or airport may similarly have an influence on purchas- ing decisions. Outside biases toward airlines or airports may influence non-financial decisions with regard to certain types of GSE operations. The business climate may also nurture future economic trends that could influence GSE decisions contrary to existing economic conditions. Regulatory Considerations Certain regulatory requirements influence the decision to purchase and/or operate alternative- fuel GSE. Regulatory requirements may exist at the national, state, and/or local level. Examples of regulatory agencies include the U.S. DOT, FAA, U.S. EPA, and the Occupational Safety and Health Administration. Airlines and airports will need to take into account all pertinent local, state, and federal laws and regulations when considering what type of GSE to operate at the air- port. Where the laws and/or regulations are vague, the airline and airport must make a qualita- tive judgment in the decision-making process. Weather and Climate Certain GSE fuel types may have differing efficiencies depending on weather conditions. The airline and airport management need to determine if their airport operating environment is

70 airport Ground Support equipment (GSe): emission reduction Strategies, Inventory, and tutorial suitable for the fuel type and GSE being considered. For example, diesel GSE may provide better operating performance than biodiesel GSE in extreme cold weather climates because of potential cold-temperature gelling of biodiesel (without fuel additives). Therefore, some GSE powered by non-conventional fuels may be better suited for warmer weather environments. The airline and airport need to include the expected weather conditions as a qualitative consideration for operating GSE. GSE Needs The airline and airport will need to determine the task that needs to be accomplished and the GSE type that would be matched to accomplish that task (e.g., “the right tool for the right job”). The airline and airport do not wish to purchase GSE that underperforms or overperforms but rather matches the GSE specifications to the operational objective. The airline and airport will need to take into consideration the availability of various fuels when evaluating the type of GSE that will be used at the airport.