Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
31.1 Summary There is a growing disparity between the growth rate of demand for petroleum-based fuels, such as Jet A fuel and diesel, and available petroleum-based fuel production, as well as an increasing awareness of airport source contribution to local air quality and global climate change. In response, the introduction of more environmentally beneficial substitutes for Jet A is anticipated within the next decade. Currently, Jet A is used to power turbine engines on aircraft, while ground sup- port equipment (GSE) is fuelled by diesel, unleaded gasoline, compressed natural gas, or electricity. However, given the sim- ilarities between diesel fuel and Jet A, it is possible, though not currently permissible, to operate diesel-powered GSE using Jet A. Fueling GSE with the substitute jet fuels may offer addi- tional benefits to airports. Within the next decade, it is anticipated that fuels cre- ated from Fischer-Tropsch (F-T) synthesis and hydropro- cessing of renewable oils [both are classified as synthetic paraffinic kerosene (SPK) fuels for the purposes of this report] could be commercially available, and/or an ultralow sulfur (ULS) standard for Jet A could be introduced. ASTM has already certified a 50-50 SPK blend (with fuels created by the F-T process), and the Commercial Aviation Alternative Fuels Initiative (CAAFI) has a goal of certifying a hydroprocessed renewable jet (HRJ) fuel as a blending feedstock by the end of 2010. It is also conceivable that the existing fuel specification may be modified to reduce maximum fuel sulfur content. This report describes the research conducted on ACRP Project 02-07, Handbook for Analyzing the Costs and Benefits of Alternative Turbine Engine Fuels at Airports. It provides information on development of the Alternative Fuels Investi- gation Tool (AFIT), a computational tool to assess the costs associated with using alternative fuels at airports and emis- sions benefits that may result from using those fuels. AFIT is a key product of this project. Much of the research conducted for the project underlies the computations made in AFIT. Subsequent sections of this report describe the literature search, airport surveys, analysis of environmental factors, and practical considerations for using alternative fuels at airports, both in aircraft and as diesel replacement fuel for GSE. The AFIT tool and handbook are described, as are some limita- tions that result from the quality of the underlying data and the fact that alternative jet fuels are not yet commercial. 1.2 Handbook Purpose The primary purpose of this project was to develop a hand- book that will allow airport operators and/or fuel suppliers or other interested parties to perform a costâbenefit analysis in a consistent manner for using a drop-in alternative to Jet A as well as evaluating the benefits of expanding the use of a drop- in alternative to Jet A to previously diesel-powered GSE. The important elements of this assessment procedure have been incorporated into AFIT. The tool incorporates a methodology for estimating the costs and benefits of providing the fuel for existing airports, airport expansions projects, and new airports. This methodology provides a list of considerations for the fuel delivery infrastructure, including obtaining, storing, and dis- tributing the fuels at the airport as well as any required infra- structure or maintenance changes. Environmental changes associated with the use of the fuels in diesel-powered GSE and in turbine-powered aircraft main engines are also assessed. The handbook considers the relative costs and benefits of using an alternative fuel compared to a fuel that is already in production and available at the airport. However, the process by which the fuel is derived is important to understand the life-cycle costs and benefits from using the fuel. Alternative fuel life-cycle data is included for several production routes so that life-cycle emission benefits can be determined com- paring the alternative fuel to conventional Jet A. Also, the handbook provides the decision maker with a consistent basis for assessing the relative difference in benefits or costs from C H A P T E R 1 Introduction
fueling GSE and aircraft with the same fuel versus continuing to fuel GSE using conventional fuel. In order to develop the handbook, a comprehensive lit- erature search, airport surveys, and an analysis of the driv- ing environmental factors were conducted. An assessment of on-airport infrastructure considerations when transitioning to an alternate fuel was evaluated, and estimates of emission factors for the new fuels were developed. These assessments are incorporated into the costâbenefit computational mod- ule, AFIT. The accompanying handbook describes the use of the tool. 1.3 Economic Considerations It is anticipated that SPK fuels will deliver benefits for airport operators. They offer the potential to ensure supply stability and possibly reduce price volatility. In addition, the possibility of a single fuel that could be used in both aircraft and ground support equipment may allow airports to reduce the amount of fuel distribution equipment, including tanks, pumps, and other peripheral equipment. Assuming the alternative jet fuel received by an airport is a drop-in fuel, then currently used seals (including O-rings) required in fuel distribution sys- tems will function satisfactorily. This is discussed more fully in Chapter 2. 1.4 Environmental Considerations Particulate matter (PM) is one of the six criteria air pol- lutants that the U.S. Environmental Protection Agency (U.S. EPA) regulates through the Clean Air Act Amendments of 1990 (Public Law 101-549), and it is of particular concern for air- ports. PM specifically refers to a complex mixture of solid par- ticles and liquid droplets that are suspended in the atmosphere. Sources include fuel combustion emissions from transporta- tion, industry, and electricity generation; forest fires; and wind-blown dust. Because PM with smaller diameters has greater health impacts than larger diameters (Greco et al., 2007), PM is referred to by its size in micrometers (µm), and the NAAQS has two listings for particulate pollution, PM10 and PM2.5, to reflect PM with diameters less than 10µm and 2.5µm, respectively. Aircraft gas turbines and ground support equipment contribute directly to ambient concentrations of PM2.5 through engine emissions (these emissions are referred to as primary PM); these vehicles also contribute indirectly to the formation of PM2.5 through gaseous emissions of nitro- gen oxide (NOx) and sulfur oxide (SOx), known as precursor gases, which undergo chemical and physical processes in the jet plume and atmosphere to form PM2.5. Although the health impacts of primary PM are greater than those of secondary PM on a per-mass basis, the larger total mass of emitted secondary PM leads to both primary and secondary PM having significant effects on the health and welfare of the general public. In addition to concerns regarding surface air quality, there is growing pressure on aviation to reduce its greenhouse gas (GHG) emissions. Aviation contributes roughly 2% of the worldâs CO2 emissions (Intergovernmental Panel on Climate Change, 1999), and recently it has received considerable atten- tion regarding these emissions. The attention is most acute in Europe, where rules are already in place to put all EU and some international aviation under the EUâs carbon cap-and- trade framework. Multiple expansion projects in the London area have been blocked based on concerns regarding aviationâs contribution to climate change, and several of the protests have caught the attention of the international news media. Within the United States, recent domestic legislation, specifi- cally Section 526 of the Energy Independence and Security Act of 2007 (Public Law 110-140), has placed restrictions on the alternative fuels that can be used by federal agencies; these restrictions are based on life-cycle greenhouse gas emissions. Carbon dioxide is not the only aircraft emission that has an impact on global climate change. The full effects include those from CO2, water (H2O) emissions, the indirect forcing from changes in the distributions and concentrations of ozone and methane as a consequence of nitrogen oxide (NOx) emissions, the direct effects (and indirect effects on clouds) from aerosols and aerosol precursors, and the effects associated with con- densation trails (contrails) and high-altitude (cirrus) clouds. Each of these emissions and effects has a varied residence time within the atmosphere; CO2 has a residence time of 50 to 200 years, methane of 8 to 10 years, ozone on the order of months, water vapor and NOx on the order of weeks, and con- trails and cirrus clouds on the order of hours. Taken together, these individual effects act to further increase the warming effect of aviation relative to that associated with CO2 alone, although the relative amount of this additional warming is still the subject of scientific study (Intergovernmental Panel on Climate Change, 1999 and Wuebbles et al., 2007). In addition, the emissions from fuel production also lead to global climate change; these well-to-tank emissions include CO2, methane, and nitrous oxide. Because of the scientific uncertainty regard- ing the impact of the non-CO2 combustion emissions on global climate change, however, this report focuses on emis- sions from fuel production and carbon dioxide emissions from combustion only. Environmental considerations are discussed in Chapters 3 and 4. 1.5 System Boundary For the purposes of this study, aircraft main engines and the GSE that operates solely on the âairsideâ of the airport are considered. This includes GSE such as baggage tugs and tow tractors but explicitly does not include airport shuttles to parking lots and other âlandsideâ operations. Aircraft aux- 4
iliary power units (APU) are not included in the analysis because there is insufficient information on emission factors for these engines to conduct an environmental analysis. Their fuel use and emissions are very small relative to the aircraft main engines. Additionally, jet fuel is not a drop-in fuel for gasoline engines; therefore, only turbine-powered aircraft main engines and diesel-powered GSE are considered. All off-airport and on-airport fuel-handling infrastructure is included in the scope of the study. This includes fuel trans- port from production facilities along traditional transportation corridors to airport receiving stations; the fuel tanks and asso- ciated pumps, filters, and piping on the airport; and the fuel delivery equipment, including hydrant systems, fuel trucks, and fuel dispensers. 5