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SUMMARY ALTERNATIVE FUELS IN AIRPORT FLEETS Alternative fuel use presents a valuable opportunity for airports to reduce emissions, man- age fuel costs, reduce petroleum dependence, increase energy security, potentially reduce maintenance efforts, increase energy security, and strengthen their public image. How- ever, navigating the complex procurement, operational, and environmental decision mak- ing associated with alternative fuels can be challenging for airports of any size or location. Although most transportation fuel used at airports is consumed by aircraft, airports often have sizable fleets of hundreds or even thousands of on- and off-road vehicles. The objective of this synthesis report is to compile airport experiences using alternative transportation fuels in airport-owned or airport-contracted vehicles, including the follow- ing vehicle functional categories: shuttles, emergency response and security, and facility and maintenance. In total, 41 airports were sent a request to complete a comprehensive online survey. Of these, 33 airports completed the survey, a response rate of 80%. In addi- tion, 16 of the respondent airports also participated in follow-up interviews by teleconfer- ence. This report is designed for use by airport senior management, fleet managers, airport environmental managers, procurement staff, and capital finance managers. This synthesis report considers eight alternative fuels: biodiesel, renewable diesel, com- pressed natural gas (CNG), renewable natural gas, liquefied natural gas, liquefied petroleum gas, hydrogen, and electricity. Notably, ethanol and hybrid-electric vehicles (HEVs) are not included in this report because the driving experience and refueling operations associated with ethanol and HEVs are well understood and documented elsewhere. Figure 1 presents the airports that responded to the survey and their approximate fuel use mixes in airport-owned and airport-contracted vehicles. Greater detail on airport experiences can be found in chapter four, organized by fuel type, and chapter five, organized by vehicle type. FIGURE 1 Map showing airport responses to online survey.
2 The online survey and phone interviews produced the following key observations: â¢ The use of alternative fuels has risen steadily in airport vehicle fleets since the early 1990s, in both the total number of airports using alternative fuels and the diversity of the fuel types used. â¢ Airports purchase alternative fuel vehicles for a variety of reasons, most notably to main- tain an environmentally friendly image and to reduce greenhouse gas (GHG) emissions. â¢ Airports vary in their willingness to try new fuels. Phone interviews revealed the follow- ing factors explain much of that variation: (1) fuel availability in the airportâs geographic region; (2) the airportâs spatial footprint and the consequent driving distance between refueling stops; (3) the existence of tunnels, which preclude the use of certain gaseous fuels; (4) the frequency of extreme snow events; (5) the existence of policies that require the use of alternative fuels; (6) the existence of government incentives that lower the cost of alternative fuels; and (7) the degree of stakeholder and community involvement. â¢ Among the fuels considered in this synthesis report, CNG is used at the greatest num- ber of airports (71% of airports surveyed). However, the fastest-growing fuel type in the past 5 years is electricity, used at 64% of airports surveyed. â¢ Buses and shuttle buses are often the first vehicle types that an airport considers good candidates for alternative fuels because (1) they create high levels of pollution near pedestrians; (2) they tend to have highly predictable duty cycles, which makes it rela- tively simple to plan refueling events; and (3) they are publicly visible, enabling air- ports to present an environmentally friendly image. â¢ A key concern airports expressed about the use of alternative fuels in buses and shuttle buses is the negative publicity that could be created if vehicles become inoperable or are out of service for extended periods. â¢ Most airports undertake the same three-step process when considering the use of a new alternative fuel: (1) identify available vehicle options that use a given fuel, (2) determine the costs and benefits of the alternative versus petroleum-based fuels, and (3) examine options for external and internal financing of vehicles, fuels, and infrastructure. â¢ Airports reported receiving a great amount of value from bi-fuel vehicles, such as vehicles that can use CNG or diesel/gasoline. Bi-fuel systems help ensure a vehicleâs reliability when one of the fuels has an inoperable refueling station. â¢ The use of certain low-carbon fuels such as renewable natural gas and renewable die- sel is limited in airport fleets, but the fuels are promising because of their competitive costs and their ability to dramatically decrease GHG emissions. â¢ Most alternative fuel dispensing stations are owned by private firms that operate both on- and off-airport. CNG and electric charging stations are exceptions; they are mostly airport-owned. â¢ Of the airports interviewed, 83% reported needing to construct new alternative fuel infrastructure when introducing a new alternative fuel, rather than being able to lever- age existing infrastructure in the region. â¢ At some airports, a major barrier to alternative fuel use is the limited selection of vehicles in the procurement system resulting from (1) âBuy Americaâ requirements, or (2) requirements to procure vehicles only from a given automaker (e.g., Ford). A qualitative summary table (Table 1) depicts attributes of each fuel type. Further details about each attribute are provided in the report. The interview results revealed several future research needs: â¢ Research on the lifetime durability of alternative fuel vehicles compared with con- ventionally powered vehicles. Survey respondents noted the lack of information on alternative fuels at the middle and end of vehiclesâ lifetime. â¢ Market assessment of emerging fuels associated with deep reductions in GHG emis- sions, such as electricity, renewable natural gas, renewable diesel, and hydrogen.
3 â¢ A handbook or tool that helps airports conduct costâbenefit analyses on alternative fuel vehicles at their airports, and provides guidance on determining the environ- mental, social, and economic costs and benefits associated with vehicle procurement, maintenance, operation, and disposal. TABLE 1 QUALITATIVE COMPARISON OF ALTERNATIVE FUELS P as se ng er C ar Fuel Cost Vehicle Cost Fuel Availability Vehicle Availability GHG Emissions (kg/mi) Air Quality (Tailpipe Emissions Only) NOx (g/mi) PM2.5 (mg/mi) PM10 (mg/mi) CO (g/mi) Gasoline1 0.31 0.12 4.78 5.41 2.7 Hydrogen2 * 0.26 0 0 0 0 Electric3 0.21 0 0 0 0 H ea vy -D ut y P ic ku p T ru ck Fuel Cost Vehicle Cost Fuel Availability Vehicle Availability GHG Emissions (kg/mi) Air Quality (Tailpipe Emissions Only) NOx (g/mi) PM2.5 (mg/mi) PM10 (mg/mi) CO (g/mi) Diesel4 0.62 1.15 21.89 25.22 0.46 BD205 0.53 0.94 10.89 11.84 0.37 RD1006 0.44 0.94 10.89 11.84 0.37 CNG 0.55 0.46 10.16 11.48 7.49 LPG 0.55 0.46 10.16 11.48 7.49 RNG7 No data ** 0.09 0.46 10.16 11.48 7.49 T ra ns it B us Fuel Cost Vehicle Cost Fuel Availability Vehicle Availability GHG Emissions (kg/mi) Air Quality (Tailpipe Emissions Only) NOx (g/mi) PM2.5 (mg/mi) PM10 (mg/mi) CO (g/mi) Diesel4 3.12 1.17 21.29 23.14 0.52 BD205 2.68 1.17 21.29 23.14 0.52 RD1006 2.21 1.17 21.29 23.14 0.52 CNG 3.31 0.59 21.29 23.14 23.00 LNG 3.30 0.59 21.29 23.14 23.00 RNG7 No data ** 0.55 0.59 21.29 23.14 23.00 Electric3 1.50 0.00 0.00 0.00 0.00 Sources: Fuel cost: DOE 2017c; vehicle cost: ANL 2016b; fuel availability: DOE 2017b; vehicle availability: DOE 2017a; emissions: ANL 2016a; renewable natural gas GHG emissions: CARB n.d. Key: Worse than reference Slightly worse than reference Similar to reference Slightly improved over reference Improved over referenceReference fuel Colors should not be compared between vehicle types or columns. Notes: * Fuel currently available only in California. **Fuel available mainly on West Coast of the United States. 1. E10 gasoline. 2. Gaseous hydrogen from natural gas reforming using conventional material. 3. Electricity produced using average U.S. grid mix. 4. Low-sulfur diesel. 5. Biodiesel from average Midwest soybeans and transesterification. Mixed with low-sulfur diesel at a ratio of 20-80 biodiesel-diesel. 6. Renewable diesel from hydrotreated pyrolysis oil from forest residues. Vehicle uses 100% renewable diesel. 7. Renewable natural gas from landfill gas, upgraded to pipeline quality.