Handbook for Evaluating Emissions and Costs of APUs and Alternative Systems (2012)

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17 C h a p t e r 3 This chapter provides a step-by-step guide to calculating fuel (energy) consumption, emis- sions, and costs for various scenarios involving APUs and alternative systems. Fuel consumption and emissions can be computed for the following equipment: • Aircraft APU, • POU system, • Central system, and • Central system with airport boiler. This guidance only presents cost calculations for alternative systems as cost data for APUs are generally not available. Emissions and cost data for diesel-powered portable alternative systems are also not addressed in this chapter due to a lack of reliable data. This chapter begins with the data requirements associated with the emission calculation methodologies. The data requirements and sources discussion is followed by separate sections that identify the specific methods to calculate fuel burn/energy consumption and emissions for APUs and alternative systems and costs for alternative systems. 3.1 Data Requirements Overview and Data Sources This section of the Handbook discusses the following: • User Supplied Data—data that the user will need to supply to successfully use this Handbook or the associated Software Tool; • Handbook Supplied Data—data collected in connection with this research effort. Handbook data includes default information that the user can use in lieu of certain user supplied infor- mation, as well as fuel consumption and emission factor data. 3.1.1 User Supplied Data The Handbook and accompanying Software Tool provide default emission factors and, in some cases, default activity data. The results of the calculation methodology are greatly improved when users provide location-specific activity data. Activity can relate to the number of gates to be served by the alternative systems, the mix of aircraft operating at the aircraft parking positions that would be serviced by the alternative systems, and the amount of time an APU is used during a single landing takeoff (LTO) cycle. Users of the Handbook and Software Tool are encouraged to supply the following location-specific information (activity data) for their airport: • Number of LTO cycles by individual aircraft types—aircraft operations and fleet mix are airport specific, and thus the user should assemble this information for the gates that would Quantitative Assessments

18 handbook for evaluating emissions and Costs of apUs and alternative Systems be served by the alternative systems. For the purposes of this Handbook, aircraft fleet mix is defined in terms of five (5) aircraft categories as shown in Table 1. • APU time of use (minutes) per aircraft LTO cycle—APU use time will vary from airport to airport. Typically airports will collect gate block time and then note the amount of time on arrival and departure that the APU is in use. • Percent of the year that temperatures are cold, neutral, and hot—using annual average weather data, the user is expected to define the percentage time that aircraft cooling is needed, the percentage time when no aircraft heating or cooling is needed, and the percentage time that aircraft heating is needed. As discussed previously, the technical report for the FAA’s VALE program assumes that cooling is required when temperatures are above 50°F, and that heating is required when temperatures are below 45°F. A wide variety of data sources exist concerning the number of LTOs performed at individual airports. Aircraft type data are also needed, so as to enable the proper identification of the APUs that are in use at the airport. Airport activity data, in terms of total aircraft operations by aircraft type, are available from several sources including: • Commercially available data sources, such as OAGaviation.com or airlinedata.com; • The Airport’s Noise and Operations Monitoring Systems (ANOMS) or other data collected by the airport; • The FAA’s Enhanced Traffic Management Systems (ETMS) database; • The FAA’s Performance Data Analysis and Decision System (PDARS); • Form T-100 Reports, available from the Bureau of Transportation Statistics (BTS); and • Other FAA or airport-specific datasets. It is important to remember that in order to apply the calculation methodologies presented in this Handbook the user needs to identify the number of LTOs by aircraft type/category. There- fore if total aircraft operations data are collected from these sources, these figures must be trans- lated into LTOs, which is accomplished by dividing the operations by two. Once the number of aircraft LTOs is defined, the user can begin the process of defining APU use times per LTO. This can be done by either using APU default information contained in the FAA’s EDMS technical manual or by the use of actual gate block time. Gate block time can be estimated if the information collected shows flights (Aircraft X arrives at the gate at a time, and then departs at a time). The block time reflects the time the aircraft is at the gate. As noted earlier, there is a period while the aircraft is parked when most pilots will use the APU (assumed to be seven minutes on average). For example, if an aircraft is at the gate for 32 minutes, alternative systems could support that aircraft for 25 minutes, and the APU will be operated for 7 min- utes. Instructions related to the format of user-specific APU TIM data and use of the methods employed in this Handbook are provided in Section 3.1.2. As noted earlier, users should supply the percentage of the year that temperatures are in the ranges that necessitate aircraft heating or cooling. For those locations where data are not readily available, the default data shown in Table 2 can be used. The default percentages provided in Ambient Conditions Example Percent (%) of Year Cold Conditions (i.e., less than 45 deg. F) 25 Neutral Conditions (VALE 45-50 deg. F) 50 Hot Conditions (i.e., more than 50 deg. F) 25 Table 2. Average annual ambient conditions.

Quantitative assessments 19 Table 2 are based on one cold condition (Winter), two neutral conditions (Spring and Fall) and one hot condition (Summer). For simplicity, each condition/season is assumed to last 3 months. Weather data is available from various sources including the National Oceanic and Atmo- spheric Administration (NOAA) National Climatic Data Center (NCDC) website at a nominal cost of approximately $20 for 1 year of records. This information can be used to identify the percentage time an aircraft requires heating or cooling on an average annual basis. Ambient temperature data from the NOAA NCDC were processed for airport weather stations located in the nine FAA regions. These data, which provide region-specific annual average temperature information, are incorporated in the TEECAAS software and are presented in Appendix A. 3.1.2 Handbook Supplied Data The Handbook supplies a number of data sets for use by the user: • APU default TIM data; • APU power settings; and • Fuel flow and emission factors. APU Default TIM data: The emissions and cost calculations described in this Handbook are performed based on the use of the International Civil Aviation Organization (ICAO) set of APU modes of operation which correspond to an aircraft LTO cycle (ICAO 2007). The four APU operating modes defined by the ICAO are the following: • Start-up (APU Start); • Normal running for passenger loading (Gate Out); • High Load (Main Engine Start); and • Normal running for passenger disembarkation (Gate In). Table 3 lists the default APU TIM data for the five aircraft categories used in this Handbook. In most cases, airports planning for alternative ground power/PCA systems may not be able to obtain TIM information for each of these APU modes; total APU use times may be available rather than times for the individual modes. Information provided in this Handbook is compat- ible with the ICAO manual to enable the Handbook methodology to use that information. The actual amount of time that aircraft spend at the gate varies widely by aircraft, airport, and airline. User supplied TIM data will need to be reconciled with the APU TIM categories above, as the APU emission factors are directly related to these TIM categories. Based on how VALE Aircraft Category APU Start (min/LTO) Gate Out (min/LTO) Main Engine Start (min/LTO) Gate In (min/LTO) Total APU Use (min/LTO) Total Ground- Based Infrastructure Use (min/LTO) Narrow Body 3 3.60 0.58 15 22.18 18.6 Wide Body 3 3.60 0.58 15 22.18 18.6 Jumbo-Wide Body 3 5.30 2.33 15 25.63 18.6 Regional Jet 3 3.60 0.58 15 22.18 18.6 Turbo Prop 3 3.60 0.58 15 22.18 18.6 APU TIM data source: ICAO, 2007. Note that consistent with the FAA’s VALE Technical Report, the alternative systems would only be used during the Gate Out TIM and the Gate In TIM. Table 3. APU activity information—default times in mode (TIM).

20 handbook for evaluating emissions and Costs of apUs and alternative Systems applications have been prepared for a number of airports, gate block time can be collected and then adjusted down by seven minutes to account for the time the APU will be in operation dur- ing the “Gate In” and “Gate Out” modes. The adjusted gate block time reflects the total time that the aircraft is located at the gate and incorporates the four TIM categories presented in Table 3. In general, gate block time should be separated proportionally into the “Gate Out” and “Gate In” modes once the user has subtracted the 3 minutes spent in “APU Start” and the time spent in “Main Engine Start” mode. When aircraft are parked at the gate longer than the total APU times shown in Table 3, the user should proportionally increase the times spent in the “Gate In” and “Gate Out” modes. Users should only alter the “APU Start” or “Main Engine Start” mode times presented above if they have obtained specific information about these modes from the airlines operating at the airport. APU Power Settings: Emission factors that have been developed for APUs are based on the power or load that is being applied. Table 4 identifies the APU power settings for the four APU operating modes and three ambient conditions (i.e., cold, neutral, and hot). As shown in Table 4, there are three distinct power settings for APUs: No-Load, Environmental Control System, and Main Engine Start. The three APU power settings are described below: • No-Load (NL): Lowest power setting used during the “APU Start” mode • Environmental Control System (ECS): Normal running condition used to support the “Gate In” and “Gate Out” modes • Main Engine Start (MES): Highest power setting used to support the start of the main engines APU Emission Factors and Fuel Flow: APU fuel flow and emission indices data are presented in Tables 5, 6, and 7 for the three APU power settings. An emissions index (EI) value is an emis- Mode Cold Conditions (e.g., less than 45 deg. F) Neutral Conditions (VALE 45-50 deg. F) Hot Conditions (e.g., more than 50 deg. F) APU Start NL NL NL Gate Out ECS NL ECS Main Engine Start MES MES MES Gate In ECS NL ECS Notes: NL=No-Load, ECS=Environmental Control Systems, MES = Main Engine Start SOURCE: Swedish Defense Research Agency, 2009. Table 4. APU power settings based on the combination of APU modes and ambient conditions. Aircraft Categor y F F ( kg/s ) E I C O 2 (g/kg fuel ) E I CO (g/kg fuel ) E I T HC (g/kg fuel ) E I NOx (g/kg fuel ) Narrow Body 0.021 3,155 31.75 6.53 5.45 Wide Body 0.035 3,155 10.26 0.87 7.55 Jumbo-Wide Body 0.033 3,155 9.38 0.88 7.41 Regional Jet 0.012 3,155 6.26 1.69 6.14 Turbo Prop 0.012 3,155 6.26 1.69 6.14 FF=Fuel Flow, EI= Emissions Index, CO 2 = Carbon dioxide, CO=Carbon monoxide, THC=Total hydrocarbon, NO x = N itrogen oxides Raw data source used to derive these we i g hted aver a g es: Swedish FOI, 2009. EI CO 2 from FAA’s EDMS, 2010. Table 5. APU fuel and emissions indices for the no-load (NL) condition.

Quantitative assessments 21 sion factor with the quantity of fuel (e.g., kilogram of fuel) representing the activity data. EIs are provided for the following: • Carbon dioxide (CO2); • Carbon monoxide (CO); • Total hydrocarbons (THC); and • Nitrogen oxides (NOx). APU-specific EIs and fuel flow (FF) values were obtained with permission from the Swed- ish Defense Research Agency’s APU emissions database (Swedish FOI 2009) and were used to generate weighted averages by aircraft category. These weighted averages were developed by using information regarding the number of aircraft operations performed in the United States by specific aircraft types within the five defined aircraft categories. POU System Electricity Requirements: Table 8 lists the electricity requirements for a POU system. As presented in Table 8, the electricity requirements associated with providing ground power, cooling, or heating to an aircraft are different and vary by aircraft category. The ground Aircraft Category FF (kg/s) EI CO 2 (g/kg fuel ) E I CO (g/kg fuel ) E I T HC (g/kg fuel ) E I NOx (g/kg fuel ) Narrow Body 0.033 3,155 5.72 0.43 6.85 Wide Body 0.052 3,155 1.14 0.19 10.99 Jumbo-Wide Body 0.061 3,155 0.53 0.12 10.30 Regional Jet 0.019 3,155 6.47 0.49 4.93 Turbo Prop 0.019 3,155 6.47 0.49 4.93 FF=Fuel Flow, EI= Emissions Index, CO 2 = Carbon dioxide, CO=Carbon monoxide, THC=Total hydrocarbon, NO x =Nitrogen oxides Raw data source used to derive these weighted averages: Swedish FOI, 2009. EI CO 2 from FAA’s EDMS, 2010. Table 6. APU fuel and emissions indices for the environmental control systems (ECS) condition. Aircraft Category FF (kg/s) EI CO 2 (g/kg fuel ) E I CO (g/kg fuel ) E I T HC (g/kg fuel ) E I NOx (g/kg fuel ) Narrow Body 0.038 3,155 4.94 0.29 7.64 Wide Body 0.064 3,155 0.98 0.13 11.53 Jumbo-Wide Body 0.058 3,155 0.53 0.12 11.20 Regional Jet 0.020 3,155 6.48 0.42 4.91 Turbo Prop 0.020 3,155 6.48 0.42 4.91 FF=Fuel Flow, EI= Emissions Index, CO 2 = Carbon dioxide, CO=Carbon monoxide, THC=Total hydrocarbon, NO x =Nitrogen oxides Raw data source used to derive these weighted averages: Swedish FOI, 2009. EI CO 2 from FAA’s EDMS, 2010. Table 7. APU fuel and emissions indices for the main engine start (MES) condition. Aircraft Categor y G round Power (KW) Cooling (KW) Heating (KW) Narrow Body 23.88 68.64 46.71 Wide Body 37.12 174.04 96.71 Jumbo-Wide Body 53.21 189.95 113.73 Regional Jet 13.30 39.33 16.68 Turbo Prop 26.60 31.16 12.72 SOURCE: ASE, 2011. Table 8. POU system electricity requirements.

22 handbook for evaluating emissions and Costs of apUs and alternative Systems power electricity requirements for POU systems are identical to those for central systems and central systems with airport boilers as discussed below. The ground power requirements presented in Table 8 reflect the use of a 40% diversity factor. That is, the aircraft electric consumption levels are typically assumed to be 40% of the estimated full loads. This is primarily due to the fact that gate-located power equipment is typically sized larger than the typical aircraft loads presented, so when an aircraft is conducting pre-flight start- up tests and operating many aircraft systems that are not normally operating (e.g., fuel transfer pumps, hydraulic pump motors, etc.), the gate equipment has sufficient capacity to supply the short duration peak loads presented. Central System Electricity Requirements: Table 9 lists the electricity requirements for a cen- tral system. As previously discussed, the ground power requirements presented in Table 9 reflect the use of a 40% diversity factor. That is, the electric consumption levels are 40% of the estimated full loads. Central System with Airport Boilers Electricity Requirements: Table 10 presents the power requirements for a central system with airport boilers. Alternative System Ground Power and PCA Power Settings: As presented in Table 11, alter- native systems provide different ground power and heating/cooling service based on ambient conditions and mode. It is assumed that aircraft APUs will be operated during the “APU Start” and “Main Engine Start” modes even if alternatives systems (i.e., ground power and PCA) are available. Emission Factors for Electricity Consumption and Natural Gas Boilers: Emission factors associated with electricity consumption and the use of natural gas boilers by alternative systems are presented in Table 12. Aircraft Category Ground Power (KW) Cooling (KW) Heating (KW) Narrow Body 23.88 48.84 46.71 Wide Body 37.12 130.49 96.71 Jumbo-Wide Body 53.21 152.64 113.73 Regional Jet 13.30 27.15 16.68 Turbo Prop 26.60 21.20 12.72 SOURCE: ASE, 2011. Table 9. Central system electricity requirements. Aircraft Category Ground Power (KW) Cooling (KW) Heating (KW) Heating (1,000 BTU/hr) Narrow Body 23.88 48.84 6.68 128.31 Wide Body 37.12 130.49 16.41 258.33 Jumbo-Wide Body 53.21 152.64 17.96 309.00 Regional Jet 13.30 27.15 3.74 42.90 Turbo Prop 26.60 21.20 3.74 30.00 SOURCE: ASE, 2011. Table 10. Central system with airport boilers electricity requirements.

Quantitative assessments 23 3.2 Quantifying Fuel Consumption and Emissions The common basis for the quantification of fuel consumption and emissions for APUs and alternative systems is the identification of aircraft types that the equipment will service. To sim- plify the assessments and to ensure that calculations support a planning-level of analysis, all assessments described in this chapter use the aircraft categories described in Table 1 and pre- sented below: • Narrow Body, • Wide Body, • Jumbo—Wide Body, • Regional Jet, and • Turbo Prop. The resolution of data (e.g., emission factors) and calculations performed correspond to the aircraft category level rather than to specific aircraft types. As a resource for planning consid- erations, it should be understood that the calculations presented in this Handbook reflect a first-order approximation based on the use of national average data in most instances. Although Mode Cold Conditions (e.g., less than 45 deg. F) Neutral Conditions (VALE 45-50 deg. F) Hot Conditions (e.g., more than 50 deg. F) APU Start NL NL NL Gate Out Power & Heat Power Power & Cool Main Engine Start MES MES MES Gate In Power & Heat Power Power & Cool SOURCES: Swedish FOI, 2009 and ICAO, 2007 Table 11. Alternative system ground power and PCA power setting based on the combination of APU modes and ambient conditions. Source Pollutant Emission Factor Unit s R eference Airport Boilers (Heat from Natural Gas) CO 2 0.053 g/BTU AP 42 (USEPA 1998a) CO 0.0000374 g/BT U VO C 0 .0000024 g/BT U NOx 0.0000142 g/BT U Airport Electricity Consumption (National Power Plants) CO 2 618 g/KW h A verage US Electricity Emissions - e Grid (USEPA 2010) CO 0.066 g/KW h B ituminous and Subbituminous Coal - A P 42 (USEPA 1998b) VO C 0 .0012 g/KW h S ummed VOC EFs for Bituminous and Subbituminous Coal - AP 42 (USEPA 1998b) NOx 0.954 g/KW h A verage US Electricity Emissions - e Grid (USEPA 2010) BTU = British Thermal Unit , K Wh = Kilowatt-hour, CO2= Carbon dioxide, CO=Carbon monoxide, VOC=Volatile organic compound, NOx=Nitrogen oxides SOURCES: See references in the table. Table 12. Emission factors for electricity consumption and natural gas boilers.

24 handbook for evaluating emissions and Costs of apUs and alternative Systems the calculations can potentially be improved through the use of more specific data (e.g., region- specific data), the methods presented herein are to be used strictly for planning purposes and should not be used in support of regulatory compliance. The guidance presented in this Handbook should not be used in lieu of (or in addition to) FAA- and USEPA-required methods and tools. The following is a basic formula for calculating emissions from APUs and alternative systems: Emissions Emission Factor Activity Data= ( )× ( ) An emission factor represents the rate at which a pollutant is emitted, typically expressed as some amount such as mass (e.g., kg) or volume (e.g., cubic ft) divided by time or various other forms of activity (e.g., mass of fuel burned, electricity consumed, heat used, etc.). Although the units for the emission factors and activity data can take on many different forms, leading to vari- ous “intermediate” terms, the emission calculations are still governed by this simple equation. Keeping in mind the simple equation presented above, emissions for APUs and alternative systems can be calculated in six steps. These six steps are illustrated in Figure 6 and discussed in the following paragraphs. Step 1: Calculate fuel consumption/energy consumption for the four APU modes and three ambient conditions. Formula 1A presented on the next page is used to calculate APU fuel burn. Formula 1B is used to calculate alternative system electricity consumption. Formula 1C is used to calculate alternative system heat energy consumption and is only applicable to central systems with airport boilers. Users without airport specific data will use data provided in Tables 2, 3, 4, 5, 6, Figure 6. Calculation of fuel burn/energy consumption and emissions.

Quantitative assessments 25 and 7 to compute APU fuel burn. Users without airport specific data will use data provided in Tables 2, 8, 9, 10, and 11 to compute alternative system electricity and heat energy consump- tion. Separate calculations are performed for the five aircraft categories presented in Table 1, as applicable. Step 2: Calculate emissions for the four APU modes and three ambient conditions. Formula 2A is used to calculate APU emissions. Formula 2B is used to calculate emissions from alternative systems. Formula 2C is used to convert APU THC emissions to volatile organic compound (VOC) emissions for comparison to alternative system VOC emissions. Users without airport specific data will use data provided in Tables 5, 6, and 7 to calculate APU-related emissions. Users without airport-specific data will use data provided in Table 12 to compute emissions associated with alternative systems. Separate calculations are performed for the five aircraft categories presented in Table 1, as applicable. Step 3: Sum the fuel burn/energy consumption values and emissions values within each ambi- ent condition. Separate calculations are performed for the five aircraft categories presented in Table 1, as applicable. The purpose of this step is to assemble data for each of the three ambient conditions (cold, neutral, and hot) to allow the computation of weighted average fuel burn, energy consumption, and emissions values during Step 4. Step 4: Calculate weighted average fuel burn/energy consumption and emissions using annual average weather conditions data. See Formula 3. Users without airport-specific weather data will use data provided in Table 2. Separate calculations are performed for the five aircraft categories presented in Table 1, as applicable. Step 5: Calculate total annual fuel burn and emissions by aircraft category using the results of Step 4 and user-defined or default aircraft LTO cycle data. See Formula 4. Step 6: Sum fuel burn and emissions across all five aircraft categories to arrive at airport-wide totals. Calculate APU fuel burn (FB) using the following equation: FB = FF TIM (Formula 1A) Where: FB = Fuel Burn per mode kg FF = Fuel Flow kg s TIM= Time in Mode s ) ) ( ( )( × Calculate electricity (electric energy) consumption required for ground power, heating, and cooling using the following equation: EE EP TIM (Formula 1B) Where: EE Electric Energy consumption per mode KWh EP Electric Power KW TIM Time in Mode hr ) ) ) ( ( ( = × = = = Calculate natural gas consumption required for heating using the following equation: HE HR TIM (Formula 1C) Where: HE Heat Energy consumption per mode BTU HR Heat Rate BTU hr TIM Time in Mode hr )( ) ) ( ( = × = = =

26 handbook for evaluating emissions and Costs of apUs and alternative Systems Calculate APU emissions for the four modes of APU operation and the three ambient condi- tions as follows: E FB EI (Formula 2A) Where: E = Emissions per mode g FB= Fuel Burn per mode kg EI = Emissions Index g kg ) ) ) ( ( ( = × Calculate alternative system emissions for the “Gate Out” and “Gate In” modes and the three ambient conditions as follows: E EE EF (Formula 2B) Where: E Emissions per mode g EE Electric Energy consumption per mode KWh EF Emission Factor g KWh E HE EF Where: E Emissions per mode g HE Heat Energy consumption per mode BTU EF Emission Factor g BTU ) ) ) ) ( ( ( ( ) ) ( ( = × = = = = × = = = APU THC emissions can be converted to VOC emissions through the use of the following formula (USEPA 2009; FAA 2010): E E CF (Formula 2C) Where: E VOC Emissions per mode g E THC Emissions per mode g CF Conversion Factor 1.15 VOC THC VOC THC ) ) ( ( = × = = = = APU and alternative system FB/energy consumption and emissions are weighted using annual average ambient temperature data as follows: Weighted average FB or E Cold condition FB or E % cold (Formula 3) Neutral condition FB or E % neutral Hot condition FB or E % hot Where: E Emissions per mode g FB Fuel Burn per mode kg ) ) ( ( )( ) ) ( ( = × + × + × = = Weighted average FB and emissions values are multiplied by the total number of LTO cycles per year to obtain “totals per year” by aircraft category as indicated below: Total FB yr FB LTO LTO cycles yr (Formula 4) Emissions yr Emissions LTO LTO cycles yr ) ) ( ( )( = × = ×

Quantitative assessments 27 Sample FB and emissions calculations for APUs, POU systems, central systems, and central systems with airport boilers are presented in the following sections. These sample calculations make use of the formulas presented in this section and default data presented in Section 3.1.2. 3.2.1 APU Fuel Burn and Emissions The following sets of data by aircraft category are necessary to calculate APU emissions: • Number of LTO cycles, • APU TIM values, • APU FF and pollutant EIs, and • Average yearly temperature distribution. Since fuel consumption and emissions are quantified and typically compared on a yearly basis, the starting point for APU emissions calculations is the specification of aircraft LTO cycles per year for each aircraft category at the airport of interest. This is exemplified in Table 13. For the purposes of this example, the default data for APU TIM is used from Table 3. Similarly this example makes use of the default ambient conditions data provided in Table 2 to properly use the FF and EI values in Tables 5 through 7. The APU power settings must be correlated to the different APU modes and ambient conditions (e.g., temperature conditions) to determine if heating or cooling is required. To calculate emissions, the first step is to calculate FB using Formula 1A for each time in mode and ambient condition. FB FF TIM Where: FB Fuel Burn permode kg F = × = ( ) F Fuel Flow kg s TIM Times in Mode(s) See = ( ) = Table 3( ) Emissions calculations are performed with Formula 2A. Separate calculations are performed for each pollutant and for each aircraft category. E FB EI Where: E Emissions permode g FB Fue = × = ( ) = l Burn permode kg EI Emissions Index for ( ) = a particular pollutant g kg See Tables 5( ) through 7( ) Aircraft Category LTO cycles/yr Narrow Body 40,000 Wide Body 2,000 Jumbo-Wide Body 3,000 Regional Jet 60,000 Turbo Prop 7,000 Total 112,000 Table 13. Example aircraft activity information.

28 handbook for evaluating emissions and Costs of apUs and alternative Systems Assuming the number of LTO cycles/yr for each aircraft category is specified, fuel burn and emissions are calculated for each of the four APU modes and three ambient temperature con- dition combinations. Example fuel burn, CO2 emissions, and THC emissions calculations for the “APU Start” mode and the “Narrow Body” aircraft category are presented in the following paragraphs. Please Note: Hand-calculated values presented in this section may not exactly match values presented in the summary figures due to rounding errors. TIM for “Narrow Body” aircraft and “APU Start” mode is 3 minutes (See Table 3) TIM 3m= in 60 s min 180s FB FF TIM FF for “Narrow Bod × = = × y” and “APU Start” is 0.021 kg s (See Table 5) FB 0.021 kg/s 180s 3.78 kg CO Emiss2 = ( ) × ( ) = ions 3.78 kg 3,155 g kg 11,925.9 g TH = ( ) ×    = CEmissions 3.78 kg 6.53 g kg 24.683= ( ) ×    = g These calculations are repeated for each pollutant and for each aircraft category. The THC emissions can be converted to VOC emissions as indicated below: VOCEmissions 24.683 g 1.15 28.385 g= ( )× ( ) = A set of fuel burn and emissions data for the 12 APU mode and ambient condition combina- tions must be generated. Once the 12 tables are developed, they are summed within each ambi- ent condition as indicated in Figure 7. The summed FB value for the “Narrow Body” aircraft category under cold conditions is: Summed FB FB “APU Start” FB “Gate Out” FB “= + + Main Engine Start” FB “Gate In” Summed FB 3 + = .780 kg 7.128 kg 1.330 kg 29.700 kg Summed + + + FB 41.938 kg= Each of the fuel burn and emissions values in the three tables at the bottom of Figure 7 are multiplied by the corresponding ambient temperature condition percentages in Table 2 and then summed to produce one weighted table. This process is illustrated in Figure 8. For example, the weighted average fuel burn for the “Narrow Body” aircraft category is conducted as follows using Formula 3: Weighted average APU FB Cold conditions FB= ×0.25 Neutral conditions FB 0.50 Hot co ( ) + ×( ) + nditions FB 0.25 41.938 kg 0.25 + 28.546 ×( ) = ×( ) kg 0.50 + 41.938 kg 0.25 35.242 kg ×( ) ×( ) = As each of the fuel burn and emissions values represent averages per LTO cycle, each value must be multiplied by the specified number of LTO cycles presented in Table 13. For example,

Figure 7. Sample calculations—APU fuel consumption and emissions.

Figure 8. Sample calculations—APU weighted fuel consumption and emissions.

Quantitative assessments 31 using the resulting 111,188.510 g/LTO emissions of CO2 from Figure 8, the total CO2 emissions for the “Narrow Body” aircraft category would be calculated using Formula 4 as: CO Emissions 111,188.510 g LTO 40,000 LTO2 = ( ) × yr 4,447,540,400g yr 4,447,540,400g yr 1 ( ) = = × Metric Ton 1,000,000 g 4,447.540Metric Ton= s yr The last step is to sum the fuel burn and emissions across each aircraft category to arrive at airport-wide totals as presented in Figure 9. 3.2.2 POU System Emissions The following sets of data by aircraft category are necessary to calculate POU system emissions: • Number of LTO cycles, • APU TIM values, • POU system electricity consumption rates for ground power and PCA (heating and cooling), • Electricity-based emission factors, and • Average yearly temperature distribution. Default values are provided in Section 3.1 for all of the data above with the exception of number of LTOs. To calculate electricity (energy) consumption and emissions for POU systems, the default LTO data and the APU activity data presented in Tables 3 and 13 are used as a starting point. Emissions for POU systems are calculated using information presented in Table 3, the POU system electricity requirement data presented in Table 8, and the emission factors data presented in Table 12. Please Note: Hand-calculated values presented in this section may not match exactly the values presented in the summary figures due to rounding errors. In order to calculate emissions from POU systems, the first step is to calculate the electricity (electric energy) consumption required for ground power, heating, and cooling using Formula 1B: EE EP TIM Where: EE Electric Energy consum = × = ption permode KWh EP Electric Power KW S ( ) = ( ) ee Table 8 TIM Time inMode hr See Table ( ) = ( ) 3( ) Figure 9. Sample calculations—APU total fuel consumption and emissions.

32 handbook for evaluating emissions and Costs of apUs and alternative Systems Emissions are then calculated using Formula 2B as follows: E EE EF Where: E Emissions permode g EE Elec = × = ( ) = tric Energy consumption permode KWh EF Em ( ) = ission Factor g KWh See Table 12( ) ( ) Similar to the APU mode and ambient condition combinations, alternative systems also pro- vide different ground power and heating/cooling service based on mode and ambient conditions as presented in Table 11. When all of the energy and emissions are calculated for each of the six mode and ambient condition combinations (i.e., not including the six conditions associated with “APU Start” and “Main Engine Start” when APU use is required), they need to be weighted based on average yearly ambient conditions. The default percentages in Table 2 are based on one cold condition (winter), two neutral conditions (spring and fall) and one hot condition (summer). Since the weighted values are based on a per LTO cycle basis, they need to be multiplied by the total num- ber of LTO cycles per year to obtain totals per year as indicated below: Total EE yr EE LTO LTO cycles yr Total =   ×( ) Electricity-related CO Emissions yr Electri 2 = city-related CO Emissions LTO LTO cycle 2  × s yr( ) These calculations are repeated for each of the pollutants of concern, and separate calculations are performed for each aircraft category. Since emission calculations for alternative systems are focused on the “Gate In” and “Gate Out” modes, separate emission calculations must be per- formed to account for APU-related emissions during the “APU Start” and “Main Engine Start” modes. These APU emissions should be considered separately (i.e., not added numerically to the alternative system emissions) for the following reasons: 1. Since APU emissions occur locally (in terminal areas), they contribute to local air quality issues. In contrast, power plant emissions usually occur outside of the geographic domain of the airport, and hence, generally do not cause localized air quality impacts in the vicinity of the airport. 2. Neither of the emissions is negligible. 3. Although they may be similar, VOC emissions are not equivalent to THC emissions. Rather than combining these two datasets, they should simply be considered separately as part of the scenario involving the use of an alternative system. If comparing directly with total APU emissions, then these common “APU Start” and “Main Engine Start” mode emissions will cancel out. The example calculations presented herein are based on the use of the example and default data presented in this chapter. Assuming the number of LTO cycles/yr are specified as in Table 13, example calculations for ground power electricity consumption during cold conditions for the “Narrow Body” aircraft category are: “Gate Out” mode for “Narrow Body” aircraft and cold conditions (See Tables 2, 8, and 11) TIM 3.6min x 1 hr 60 min 0.06 hr EE (23. = = = 88 KW) (0.06 hr) 1.433 KWh× =

Quantitative assessments 33 This is repeated for the heating and cooling operations, and then the energy consumption values are summed accordingly to match the combinations specified in Table 11. For example, electric energy consumption from ground power is combined with electric energy consumption for cabin heating: Total electric energy consumption ground po= wer electric energy cabin heating electric+ energy 1.433 KWh 2.802 KWh 4.235 KWh = + = Emissions are calculated as exemplified by this CO2 emissions calculation: CO Emissions 4.235 KWh 618 g KWh 2,6172 = ( )× ( ) = g Once the six tables (one for each of the six APU mode and ambient combinations) are devel- oped, they are summed within each ambient condition as presented in Figure 10. The three tables at the bottom of Figure 10 represent the sum of the energy and emissions data for the “Gate Out” and “Gate In” modes with each table corresponding to one of the three ambient conditions. The summed electric energy value for the “Narrow Body” aircraft category under the cold ambient condition is: Summed electric energy 4.235 KWh 17.648 KWh= + = 21.883 KWh The energy and emissions values in the three tables at the bottom of Figure 10 are multiplied by the corresponding percentages in Table 2 and then summed to produce one weighted table as illustrated in Figure 11. For example, the weighting for electric energy consumption for the “Narrow Body” aircraft category is conducted using Formula 3 as follows: Weighted average EE Cold EE 0.25 Neutral= ×( )+ EE 0.50 Hot EE 0.25×( )+ ×( ) 21.883 KWh 0.25 7.403 KWh 0.50 28.68= ×( )+ ×( )+ 1 KWh 0.25 16.342 KW ×( ) = h The energy use and emissions data are summed across each aircraft category to arrive at airport- wide totals as presented in Figure 12. The final step is to separately consider APU emissions during the “APU Start” and “Main Engine Start” modes of operation as illustrated in Figure 13. As previously explained, the APU and alternative system emissions data should not be summed for various reasons. They should be considered separately to allow a comprehensive understand- ing of all emissions and fuel/energy consumption associated with the use of alternative systems. 3.2.3 Central System Emissions The following sets of data by aircraft category are necessary to calculate central system emissions: • Number of LTO cycles, • APU TIM values, • Central system electricity consumption rates for ground power and PCA (heating and cooling), • Electricity-based emission factors, and • Average yearly temperature distribution.

Figure 10. Sample calculations—POU system energy consumption and emissions.

Figure 11. Sample calculations—POU system weighted energy consumption and emissions.

36 handbook for evaluating emissions and Costs of apUs and alternative Systems Similar to the evaluation process for POU systems, users can supply all of the above data or can use default data for all except the locally specific LTO cycles. To calculate electricity (energy) consumption and emissions for central systems, the aircraft activity data and the APU activity data presented in Tables 3 and 13 are used as a starting point. Note that the electricity requirements for central systems are similar to the electricity require- ments for POU systems except for cooling operations. To calculate emissions for central systems, the central system electricity requirements data presented in Table 9 are used in combination with the LTO data presented in Table 13 and the TIM data presented in Table 3. The emission factors are the same as used for the POU system calculations, and are presented in Table 12. Please Note: Hand-calculated values presented in this section may not exactly match values presented in the summary figures due to rounding errors. To calculate emissions from central systems, the first step is to calculate the electricity (electric energy) consumption required for ground power, heating, and cooling and then to calculate the emissions using Formula 1B and Formula 2B: EE EP TIM Where: EE Electric Energy consumpti = × = on permode KWh EP Electric Power KW See ( ) = ( ) Table 9 TIM Time inMode hr See Table 3 ( ) = ( ) ( ) Figure 12. Sample calculations—POU system total energy consumption and emissions. Figure 13. Sample calculations—POU system and APU (“APU start” and “main engine start” mode) energy/fuel consumption and emissions.

Quantitative assessments 37 E EE EF Where: E Emissions permode g EE Elec = × = ( ) = tric Energy consumption permode KWh EF Em ( ) = ission Factor g KWh See Table 12( ) ( ) Similar to the APU mode and ambient condition combinations, alternative systems also pro- vide different ground power and heating/cooling service based on the combination of mode and ambient conditions. The mode/ambient condition combinations for alternative systems are listed in Table 11. When all of the energy and emissions are calculated for each of the six mode and ambient condition combinations (i.e., not including the six conditions associated with “APU Start” and “Main Engine Start” when APU use is required), they need to be weighted based on average yearly ambient conditions. Since the weighted values are based on a per LTO cycle basis, they need to be multiplied by the total number of LTO cycles per year to obtain totals per year as indicated below: Total EE yr EE LTO LTO cycles yr Total =   ×( ) Electricity-related CO Emissions yr Electri 2 = city-related CO Emissions LTO LTO cycle 2  × s yr( ) The example calculations presented below are based on the use of the LTO cycles/yr data listed in Table 13. Central system electricity consumption and emissions were calculated for each of the six (6) mode and ambient temperature condition combinations. Calculations for ground power electricity consumption for the “Narrow Body” aircraft category for the “Gate Out” mode are presented below: TIM min 1 hr min 0.06 hr EE 23.88 KW = × = = ( ) 3 6 60. × ( ) = 0 06. hr 1.433 KWh These calculations are repeated for the heating and cooling operations, and then the energy consumption values are summed. For example, for cold conditions, electric energy consumption from ground power is combined with electric energy consumption for cabin heating: Total electric energy consumption ground po= wer electric energy cabin heating electric+ energy KWh 2.802 KWh 4.235 KWh = + = 1 433. Emissions of CO2 are calculated as follows for the “Narrow Body” aircraft category for the “Gate Out” mode and cold conditions: CO Emissions 4.235 KWh g KWh2 618 2 617 = ( ) × ( ) = , g Once the six tables are developed, they are summed within each ambient condition as indi- cated in Figure 14. For example, the energy values in each of the two tables on the left side of

Figure 14. Sample calculations—central system energy consumption and emissions.

Quantitative assessments 39 Figure 14 are summed to generate the total energy value in the one table at the bottom left corner. The resulting three tables at the bottom of Figure 14 represent the sum of the energy and emissions data for the “Gate Out” and “Gate In” modes with each table corresponding to one of the three ambient conditions. The summed electric energy value for the “Narrow Body” aircraft category under cold conditions is: Summed electric energy KWh KWh= +4 235 17 648. . = 21.883 KWh Each of the energy and emissions values in the three tables at the bottom of Figure 14 are multiplied by the corresponding ambient conditions percentages data presented in Table 2 and then summed to produce one weighted table as illustrated in Figure 15. For example, the weighting for electric energy consumption for the “Narrow Body” aircraft category is conducted as follows: Weighted average EE = Cold EE Neutral×( ) +0 25. EE 0.50 Hot EE 0.25 KWh ×( )+ ×( ) = ×( ) +21 883 0 25. . 7 403 0 50 22 543 0 25 14 808 . . . . . KWh KWh×( ) + ×( ) = KWh As each of the energy and emissions values in the table represent averages per LTO cycle, each value must be multiplied by the specified number of LTO cycles for each aircraft cat- egory (presented in Table 13). For example, using the resulting 9,151.298 g/LTO CO2 emis- sions in Figure 15, the total CO2 emissions for the narrow body aircraft category would be calculated as: Total Electricity-based CO Emissions2 = 9 151, . , , , 298 40 000 366 051 920 g LTO LTO yr g yr ( ) × ( ) = = 366 Metric Tons yr Then the energy and emissions are summed across each aircraft category to arrive at system level totals as presented in Figure 16. The final step is to separately consider APU emissions dur- ing the “APU Start” and “Main Engine Start” modes as presented in Figure 17. As previously explained, these two sets of data should not be summed for various reasons. 3.2.4 Central System with Airport Boiler Emissions To calculate electricity (energy) consumption and emissions for central systems using air- port boilers for heating, the default LTO data and the APU activity data presented in Tables 3 and 13 are used as a starting point. The APU TIM values serve as the underlying activity data for alternative systems to allow for an appropriate basis for comparison. To calculate emis- sions, data presented in Table 3 need to be combined with the central system electricity and heat energy requirements data presented in Table 10, and emission factors data presented in Table 12. Please Note: Hand-calculated values presented in this section may not match the values presented in the summary figures exactly due to rounding errors.

Figure 15. Sample calculations—central system total weighted energy consumption and emissions.

Quantitative assessments 41 In order to calculate emissions from central systems, the first step is to calculate the electricity (electric energy) consumption required for ground power, heating, and cooling using Formula 1B: EE EP TIM Where: EE Electric Energy consumpti = × = on permode KWh EP Electric Power KW See T ( ) = ( ) able 10 TIM Time inMode hr See Table 3 ( ) = ( ) ( ) Heat energy consumption through the airport boilers can be calculated using Formula 1C: HE HR TIM Where: HE Heat Energy consumption p = × = ermode BTU HR Heat Rate BTU hr See Table 1 ( ) = ( ) 0 TIM Time inMode hr See Table 3 ( ) = ( ) ( ) Emissions are then calculated as follows: E EE EF Where: E Emissions permode g EE Elec = × = ( ) = tric Energy consumption permode KWh EF Em ( ) = ission Factor g KWh See Table 12( ) ( ) Figure 16. Sample calculations—central system total energy consumption and emissions. Figure 17. Sample calculations—central system and APU (“APU start” and “main engine start” mode) energy/fuel consumption and emissions.

42 handbook for evaluating emissions and Costs of apUs and alternative Systems E HE EF Where: E Emissions permode g HE Heat = × = ( ) = Energy consumption permode BTU EF Emissi ( ) = on Factor g BTU See Table 12( ) ( ) As described previously, alternative systems provide different ground power and heating/ cooling service based on the combination of APU mode and ambient conditions as presented in Table 11. For cabin heating (i.e., under the cold ambient conditions), the “Power & Heat” designation in Table 11 refers to the use of ground power for electrical components (lighting, pneumatics, etc.), the use of electricity to operate AHUs, and the supply of heat from the airport boilers. The “Heat” term is used to encompass the latter two sources of energy consumption and emissions (AHUs and boilers) in a central system that uses airport boilers. The boiler heat energy consumption (BTU) is added to the overall central system electric energy consumption (KWh) using the following unit conversion: 1 0 00029BTU KWh= . When all of the energy and emissions are calculated for each of the 6 mode and ambient condition combinations (i.e., not including the six conditions associated with “APU Start” and “Main Engine Start” when APU use is required), they need to be weighted based on average yearly ambient conditions. The weighting is only conducted for electric energy consumption and corresponding emissions (i.e., not for airport boiler heat energy consumption and correspond- ing emissions). Since the resulting weighted values and the boiler results are based on a per LTO cycle basis, they need to be multiplied by the total number of LTO cycles per year to obtain totals per year as indicated by the following: Total EE yr EE LTO LTO cycles yr Total =   × ( ) Electricity-related CO Emissions yr Electri 2 = city-related CO Emissions LTO LTO cycle 2  × s yr Total HE yr HE LTO LTO cycles yr ( ) =   × ( ) Total Boiler-related CO Emissions yr Boiler 2 = -related CO Emissions LTO LTO cycles yr2   × ( ) These calculations are repeated for each pollutant of concern. Because the total electricity- related values only represent the “Gate Out” and “Gate In” modes, the APU FB and emis- sions for the “APU Start” and “Main Engine Start” modes need to be considered separately as described previously. The example calculations presented in this section rely on the LTO cycles/yr data specified in Table 13. Electricity consumption and emissions are calculated for each of the six mode and

Quantitative assessments 43 ambient condition combinations. Example calculations for ground power electricity consump- tion and heat energy consumption for the “Narrow Body” aircraft category follow. “Gate Out” and cold conditions combination: TIM hr min hr EE KW = × ( ) = = ( 3 6 1 60 0 06 23 88 . min . . ) × ( ) = = ×( 0 06 1 433 128 31 1000 . . . hr KWh HE BTU hr) × ( ) =0 06 7 698 6. , .hr BTU These calculations are repeated for the heating and cooling operations, and then the energy consumption values are summed accordingly to match the combinations specified in Table 11. For example, electric energy consumption associated with ground power is combined with elec- tric energy consumption by AHUs in the following calculations provided: Total electric energy consumption ground po= wer electric energy AHU electric energy 1. + = 433 KWh KWh KWh + = 0 401 1 834 . . Emissions are calculated as exemplified by these CO2 emissions calculations: Electricity-related CO Emissions KWh2 = (1 834. ) × ( ) =618 1 133g KWh g Boiler-related CO Emis2 , sions BTU g BTU g= ( ) × ( ) =7 698 6 0 053 408, . . This is repeated for each pollutant and for each aircraft category and each ambient tempera- ture category. Unlike the electricity-based results, only two of these boiler-based tables are necessary since the use of the boiler’s heat energy corresponds to just two mode/ambient condition combina- tions: (1) “Gate Out” and cold conditions and (2) “Gate In” and cold conditions. Once the six electricity-based tables and two boiler-based tables are developed, they are summed within each ambient condition as presented in Figures 18 and 19, respectively. For example, the energy values in each of the two electricity-related tables on the left side of Figure 18 are summed to generate the total energy value in the one table at the bottom left corner. The resulting three tables at the bottom of Figure 18 represent the sum of the energy and emissions data for the “Gate Out” and “Gate In” modes with each table corresponding to one of the three ambient conditions. In contrast, the resulting single boiler-based table presented in Figure 19 corresponds to cold conditions. The following are the summed electric energy and boiler heat energy values for the “Narrow Body” aircraft category under cold conditions: Summed electric energy KWh KWh= + =1 834 7 640. . 9 474 7 698 6 . , . KWh Summed boiler energy BTU= + 32 077 5 39 776 1, . , .BTU BTU= Each of the energy and emissions values in the three electricity-based tables at the bottom of Figure 18 and at the bottom of Figure 19 are multiplied by the corresponding

Figure 18. Sample calculations—central system with airport boiler electricity-based energy consumption and emissions.

Quantitative assessments 45 percentages in Table 2 and then summed to produce weighted tables as presented in Fig- ures 20 and 21. For example, the weighting for electric energy consumption for the “Narrow Body” aircraft category is conducted as follows: Weighted average EE Cold EE 0.25 Neutral= ×( ) + EE Hot condition EE KW ×( ) + ×( ) = 0 50 0 25 9 474 . . . h KWh KWh×( ) + ×( ) + ×(0 25 7 403 0 50 22 543 0 25. . . . . ) =11 706. KWh Similar weighting is necessary for the boiler-based results for one ambient condition (cold conditions) as indicated by the example for the “Narrow Body” aircraft category: WeightedHE Cold conditions HE= ×( ) = 0 25 39 77 . , 6 1 0 25 9 944 025 . . , . BTU BTU × = The energy and emissions values in the tables in Figures 20 and 21 represent averages per LTO cycle. Each value must be multiplied by the appropriate LTO cycles for the aircraft Figure 19. Sample calculations—central system with airport boiler heat (boiler)-based energy consumption and emissions.

Figure 20. Sample calculations—central system with airport boiler weighted electricity-based energy consumption and emissions.

Quantitative assessments 47 category of interest as presented in Table 13. For example, using CO2 emissions data from Figures 20 and 21, total CO2 emissions for the “Narrow Body” aircraft category are calculated using the following equations: Total Electricity-related CO Emissions yr2 = 7234 061 40 000 289 362 4 . , , , g LTO LTO yr   × ( ) = 40 289 362 g yr Metric Tons yr= . Total Boiler-related CO Emissions yr2 = 527 033. g LTO LTO yr g yr   × ( ) = = 40 000 21 081 320 , , , 21 081. Metric Tons yr Then the energy and emissions data are summed across each aircraft category to arrive at airport-wide totals as presented in Figure 22 below for the electricity-based results. The boiler-based results are presented in Figure 23. The final step is to separately consider the APU emissions during the “APU Start” and “Main Engine Start” modes along with the electricity-based and boiler-based results as pre- sented in Figure 24. As previously explained, these sets of data should not be summed for various reasons. They should be considered separately to allow a comprehensive understanding of all emissions and fuel/energy consumption associated with the use of alternative systems. Figure 21. Sample calculations—central system with airport boiler weighted heat (boiler)-based energy consumption and emissions.

48 handbook for evaluating emissions and Costs of apUs and alternative Systems Figure 22. Sample calculations—central system with airport boiler total electricity-based energy consumption and emissions. Figure 23. Sample calculations—central system with airport boiler total heat (boiler)-based energy consumption and emissions. Figure 24. Sample calculations—central system with airport boiler.

Quantitative assessments 49 3.3 Estimating Costs for Alternative Systems As discussed previously, this Handbook includes cost data for three types of alternative sys- tems: POU systems, central systems, and central systems with airport boilers. Portable diesel- powered systems are not included since reliable cost data could not be obtained. However, future revisions to this Handbook could potentially address portable diesel-powered systems. Cost data presented in the Handbook only allow comparison of the three types of alternative systems. The underlying cost rates represent industry averages on a national level and were supplied by AERO Systems Engineering, Inc. (ASE 2011) based on 2010 dollars. In the following sections, cost calculation methodologies are described for the following cost components: • Capital, • Operating, and • Maintenance. Similar to the emissions data presented earlier in this chapter, the cost data presented in this section are summarized by aircraft category except for maintenance costs which are based on total gate usage. Cost scenarios are based on various factors including number of gates per aircraft category, equipment life expectancy, and number of LTOs per year. Since all of the underlying cost rate data used in this Handbook generally represent 2010 values, the calculated costs can be adjusted accordingly using a suitable inflation rate to make the costs representative of current values. However, it should be noted that the development of projections based on inflation can be complicated due to the timing of cost payments and other factors. For example, operating and maintenance costs should be adjusted according to when (e.g., which year) the payments will be made. Even capital costs may not be paid in a lump sum (i.e., financing may be involved). The following sections provide directions on calculating each of the aforementioned cost components and total cost for each alternative system using 2010 cost rates. The user can then either use the 2010-based results for comparison purposes or adjust the results for inflation using a suitable approach. 3.3.1 POU System Costs 3.3.1.1 Input Data The following sets of data by aircraft category are necessary to calculate POU system costs: • Number of gates, • POU system capital costs per gate, • Cost of electricity, • POU system maintenance costs per gate, and • POU system electric energy consumption data (See Section 3.2.2). Although these datasets are necessary, the user is generally only expected to supply the num- ber of gates by aircraft category. The default data presented in this section are used for all other variables. 3.3.1.2 Results The following set of life-cycle costs by aircraft category and airport-wide totals are calculated: • Capital costs, • Operating costs, and • Maintenance costs (only airport-wide totals).

50 handbook for evaluating emissions and Costs of apUs and alternative Systems 3.3.1.3 Methodology Along with the specification of APU TIM values and the total number of LTO cycles per year for emissions calculation purposes, the number of gates also needs to be specified to calculate alternative system costs as presented in Table 14. The number of gates and the number of LTOs/yr for each aircraft category are interrelated and, therefore, must be carefully estimated to ensure proper (realistic) scenarios are modeled. The basic data used to calculate POU system costs are presented in Tables 15 through 17. Capital costs are calculated based on multiplying the number of gates by the prorated costs indicated in Table 15. The Level 1 and Level 2 option costs were approximated as being roughly the same as indicated in Table 15. The following equations are used to calculate the capital costs to install POU system ground power and PCA units: POU system capital cost POU system power ca= pital cost POU system PCA capital cost( ) + ( ) POU system power capital cost Equipment an= d basic install cost Level 1 cost +Level 2+ cost number of gates POU system PCA cap ( ) × ( ) ital cost Equipment and basic install cost= +( ) × Level 1 cost +Level 2 cost number of gates( ) Aircraft Category APU Start (min/LTO) Gate Out (min/LTO) Main Engine Start (min/LTO) Gate In (min/LTO) Example LTO/yr Example Number of Gates Narrow Body 3 3.60 0.58 15 40,000 12 Wide Body 3 3.60 0.58 15 2,000 1 Jumbo-Wide Body 3 5.30 2.33 15 3,000 4 Regional Jet 3 3.60 0.58 15 60,000 18 Turbo Prop 3 3.60 0.58 15 7,000 3 SOURCE: Environmental Science Associates, 2011. Table 14. Example number of gates specified along with other APU activity data. Aircraft Category POU Power ($/gate) POU PCA ($/gate) Equipment and Basic Install Level 1 Electric Level 2 Electric Equipment and Basic Install Level 1 Electric Level 2 Electric Narrow Body $49,000 $15,000 $15,000 $87,000 $15,000 $15,000 Wide Body $74,000 $30,000 $30,000 $108,833 $43,333 $43,333 Jumbo - Wide Body $134,000 $60,000 $60,000 $293,900 $103,500 $103,500 Regional Jet $42,000 $15,000 $15,000 $70,500 $15,000 $15,000 Turbo Prop $42,000 $15,000 $15,000 $70,500 $15,000 $15,000 Level 1 Electric: Assumes some electrical feeder work needs to be installed and that there is infrastructure to terminate into within the building. Level 2 Electric: Assumes infrastructure needs to be installed such as adding breakers to existing distribution gear, or adding bus taps existing gear and setting new distribution panels, or adding switchgear sections. SOURCE: ASE, 2011. Table 15. POU system capital costs.

Quantitative assessments 51 These calculations are performed for each of the five aircraft categories, as applicable. Then, the individual costs are summed to obtain the total capital cost. Operating costs for POU systems are calculated using an average cost rate for electricity ($/KWh) as presented in Table 16, total electricity consumption per year (KWh/yr) data, and information regarding the anticipated useful life of the POU system equipment. POU system operating cost Total electric en= ergy consumption, KWh yr cost of electric ( ) × ity, $ KWh number of years equipment used ( ) × ( ) Similar to capital costs, these calculations can be performed for each of the aircraft categories if cost per category is necessary. Otherwise, the total electric energy consumption for all aircraft categories can be used. To calculate maintenance costs, the total number of gates across all aircraft types is used as follows: POU systemmaintenance cost Total number of= gates POU systemmaintenance cost, $ gat ( ) × e-yr number of years equipment used ( ) × ( ) Cost Factors Example Cost Rates Average Cost of Electricity ($/KWh) 0.07 Average Cost of Natural Gas ($/mmBtu) 4 SOURCE: ASE, 2011. Table 16. Nominal electricity and natural gas costs. Number of Gates POU System Maintenance Cost ($/gate-yr) <8 $5,698 8 $5,698 16 $5,698 24 $5,698 30 $5,698 40 $5,698 50 $5,698 60 $5,698 70 $5,698 80 $5,698 90 $5,698 100 $5,698 >100 $5,698 SOURCE: ASE, 2011. Table 17. POU system maintenance costs per gate.

52 handbook for evaluating emissions and Costs of apUs and alternative Systems As indicated in Table 17, the POU system maintenance cost rate is constant (not adjusted based on the number of gates to be served by the POU system). This is due to the fact that each gate requires the same effort to maintain, and therefore, the costs are additive. Although this table could be simplified, its format is maintained for consistency with the corresponding rates used for central systems. POU systems are considered to have a life span of approximately 15 years while central systems are considered to have life spans of about 20 years (the FAA’s VALE program technical man- ual specifies that PCA units have life spans of about 13 years and ground power equipment are expected to have life spans of about 20 years). Therefore, cost assessments should generally be con- ducted within the limits of the life spans. However, if a cost assessment needs to surpass the POU’s life span (i.e., if conducting a 20-year comparison assessment against a central system), then the maintenance costs for POUs need to be increased by 3% of the initial capital cost per gate per year. The total cost of a POU system is simply the addition of the three cost components: Total POU system cost POU system capital co= st POU system operating cost POU syste ( ) + ( ) + mmaintenance cost( ) As previously explained, these costs can be modified as necessary to reflect present day values using a suitable inflation rate such as 2%. 3.3.1.4 Example Calculations The example calculations presented below are based on the use of the example and default data presented in this chapter and assuming a 15-year usage period. Using the LTO cycles/yr and gates data specified in Table 14, the POU system capital cost for the narrow body aircraft category is: POU system power capital cost gate= +$ , $49 000 15 000 15 000 79 000 , $ , $ , gate gate gate POU syst + = emPCA capital cost gate gat= +$ , $ ,87 000 15 000 e gate gate POU system capit + = $ , $ , 15 000 117 000 al cost gate gate gates= + × ($ , $ ,79 000 117 000 12 ) = $ , ,2 352 000 These calculations are repeated for each of the other aircraft categories using the LTO cycle data presented in Table 14, resulting in the final values shown in Table 18. Operating costs are calculated using the total electric energy consumption data presented in Figure 25. The operating cost for the narrow body aircraft category is: Narrow body aircraft category electric energy consumption MWh yr KWh yr = = 653 697 653 697 . , Note: 1MWh KWh POU system operatin =( )1 000, g cost KWh yr KWh years= ( ) × ( ) ×653 697 0 07 15, $ . ( ) = $ ,686 382

Quantitative assessments 53 Narrow body aircraft category electric energy consumption MWh yr KWh yr = = 653 697 653 697 . , Note: 1MWh KWh POU system operatin =( )1 000, g cost KWh yr KWh years= ( ) × ( ) ×653 697 0 07 15, $ . ( ) = $ ,686 382 These calculations are conducted for each aircraft category and then summed as shown below in Table 19. As with the emissions calculations, these costs represent average weighted values because the electric energy consumption values account for the distribution of ambient conditions (i.e., 25% cold, 50% neutral, and 25% hot). For maintenance costs, the total number of gates (38) shown in Table 14 is used as follows: POU systemmaintenance cost gates= ( ) ×38 5 6$ , 98 15 3 247 860 gate-yr years( ) × ( ) = $ , , Aircraft Category Capital Cost ($) Narrow Body $2,352,000 Wide Body $329,500 Jumbo-Wide Body $3,019,600 Regional Jet $3,105,000 Turbo Prop $517,500 TOTAL = $9,323,600 Table 18. POU system capital costs— example calculations. Figure 25. Sample electric energy consumption data—POU system. Aircraft Category Operating Cost ($) Narrow Body $686,382 Wide Body $68,230 Jumbo-Wide Body $137,620 Regional Jet $533,218 Turbo Prop $85,603 TOTAL = $1,511,053 Table 19. POU system operating costs—example calculations.

54 handbook for evaluating emissions and Costs of apUs and alternative Systems The total cost is calculated as: Total POU system cost = +$ , , $ , ,9 323 600 1 511 053+ = $ , , $ , , 3 247 860 14 082 513 3.3.2 Central System Costs Input Data The following sets of data by aircraft category are necessary to calculate central system costs: • Number of gates, • Central system capital costs per gate, • Cost of electricity, • Central system maintenance costs per gate, and • Central system electric energy consumption data (See Section 3.2.3). Although these datasets are necessary, the user is generally only expected to supply the number of gates by aircraft category. The default data presented in this section are used for all other variables. Results The following set of life-cycle costs by aircraft category and airport-wide totals are calculated: • Capital costs, • Operating costs, and • Maintenance costs (only airport-wide totals). Methodology Along with the specification of APU TIM values and the total number of LTO cycles per year for emissions calculation purposes, the number of gates also needs to be specified to calculate alternative system costs as presented in Table 14. The number of gates and the number of LTOs/yr for each aircraft category are interrelated and, therefore, must be carefully estimated to ensure proper (realistic) scenarios are modeled. The basic data used to calculate central system costs are presented in Tables 20 and 21. Informa- tion presented previously in Table 16 is also used to calculate central system costs. Capital costs are calculated based on multiplying the number of gates by the prorated costs indicated in Table 20. Central system capital cost Central system= power capital cost Central system PCA capi+ tal cost total number of gates ( ) × ( ) Aircraft Categor y Central Power ($/gate) Central PCA ($/gate) Equipment and Basic Instal l E quipment and Basic Instal l Narrow Body $52,741 $228,283 Wide Body $82,493 $313,779 Jumbo — Wide Body $164,986 $644,166 Regional Jet $37,974 $197,154 Turbo Prop $37,974 $197,154 SOURCE: ASE, 2011 . Table 20. Central system capital costs.

Quantitative assessments 55 These calculations are performed for each of the five aircraft categories, as applicable. Then, the individual costs are summed to obtain the total capital cost. Operating costs for central systems are calculated using an average cost rate for electricity ($/KWh) as presented in Table 16; total electricity consumption per year (KWh/yr) data; and information regarding the anticipated useful life of the central system equipment. Central system operating cost Total electri= c energy consumption, KWh yr cost of elec ( ) × tricity, $ KWh number of years equipment ( ) × used( ) Similar to capital costs, these calculations can be performed for each of the aircraft categories if cost-per-category is necessary. Otherwise, the total electric energy consumption for all aircraft categories can be used. To calculate maintenance costs, the total number of gates across all aircraft types is used as follows: Central systemmaintenance cost Total numbe= r of gates Central systemmaintenance co ( ) × st, $ gate-yr number of years equipment u ( ) × sed( ) As presented in Table 21, the lowest number of gates shown is eight. This is to indicate that central systems should not be used to support fewer than eight gates, as POU systems would be more cost effective. Finally, the total cost is simply the addition of the three cost components: Total Central system cost Central system ca= pital cost Central system operating cost ( ) + ( ) + ( )Central systemmaintenance cost Number of Gates Central System Maintenance Cost ($/gate-yr) 8 $3,404 16 $2,870 24 $2,700 30 $2,636 40 $2,615 50 $2,557 60 $2,533 70 $2,524 80 $2,510 90 $2,490 100 $2,485 >100 $2,480 SOURCE: ASE, 2011. Table 21. Central system maintenance costs.

56 handbook for evaluating emissions and Costs of apUs and alternative Systems As previously explained, these costs can be modified as necessary to reflect present day values using a suitable inflation rate such as 2%. Example Calculations The example calculations presented herein are based on the use of the example and default data presented in this chapter and assuming a 15-year usage period. Assuming the number of LTO cycles/yr and gates are specified as in Table 14, the central system capital cost for the narrow body aircraft category is: Central system capital cost gate= +$ , $52 741 228 283 12 3 372 297 , $ , , gate gates( ) × ( ) = These calculations are repeated for each of the other aircraft categories resulting in the final values shown in Table 22. Operating costs are calculated using the total electric energy consumption data developed from the emissions calculations as presented in Figure 26. The operating cost for the narrow body aircraft category is: Narrow body aircraft category electric energy consumption 592.317 MWh yr 592,317 KWh yr = = Note: 1MWh 1,000 KWh Central system oper =( ) ating cost 592,317 KWh yr $0.07 KWh 15 y= ( )× ( )× ears $621,933 ( ) = These calculations are conducted for each aircraft category and then summed as shown in Table 23. Aircraft Category Capital Cost ($) Narrow Body $3,372,297 Wide Body $396,272 Jumbo-Wide Body $3,236,608 Regional Jet $4,232,297 Turbo Prop $705,383 TOTAL = $11,942,857 Table 22. Central system capital costs— example calculations. Figure 26. Sample electric energy consumption data—central system.

Quantitative assessments 57 As with the emissions calculations, these costs represent average weighted values because the electric energy consumption values account for the distribution of ambient conditions (i.e., 25% cold, 50% neutral, and 25% hot). For maintenance costs, the total number of gates (38) shown in Table 14 is used to interpolate for the maintenance cost rate in Table 21: 30 2,636 38 ? 40 2,615 Central systemmaintenance cost rate for 38 gates 38 30 40 30 2,615 2,636= −( ) −( )     × −( )  + = 2,636 $2,619.2 gate-yr Then the maintenance cost is calculated as: Central systemmaintenance cost 38 gates= ( )× $2,619.2 gate-yr 15 years $1,492,944 ( )× ( ) = The total cost is calculated as: Total Central system cost $11,942,857 $1,36= + 4,433 $1,492,944 $14,800,234 + = 3.3.3 Central System with Airport Boiler Costs 3.3.3.1 Input Data The following sets of data by aircraft category are necessary to calculate central system with airport boiler costs: • Number of gates, • Central system capital costs per gate, • Cost of electricity, • Cost of natural gas, • Central system maintenance costs per gate, and • Central system electric energy consumption data and heat energy consumption data (See Section 3.2.4). Aircraft Category Operating Cost ($) Narrow Body $621,933 Wide Body $61,142 Jumbo-Wide Body $127,680 Regional Jet $473,749 Turbo Prop $79,930 TOTAL = $1,364,433 Table 23. Central system operating costs—example calculations.

58 handbook for evaluating emissions and Costs of apUs and alternative Systems Although these datasets are necessary, the user is generally only expected to supply the num- ber of gates by aircraft category. The default data presented in this section are used for all other variables. 3.3.3.2 Results The following set of life-cycle costs by aircraft category and airport-wide totals are calculated: • Capital costs, • Operating costs, and • Maintenance costs (only airport-wide totals). 3.3.3.3 Methodology Along with the specification of APU TIM values and the total number of LTO cycles per year for emissions calculation purposes, the number of gates also needs to be specified to calculate alternative system costs as presented in Table 14. The number of gates and the number of LTOs/yr for each aircraft category are interrelated, and therefore, must be carefully estimated to ensure proper (realistic) scenarios are modeled. The basic data used to calculate central system costs were previously presented in Tables 16, 20, and 21. Capital costs are calculated based on multiplying the number of gates by the prorated costs indicated in Table 20: Central system capital cost Central system= power capital cost Central system PCA ca ( ) + pital cost( ) These calculations are performed for each of the five aircraft categories, as applicable. Then, the individual costs are summed to obtain the total capital cost. Capital costs associated with the use of the airport boilers’ heat energy are relatively small and are not evaluated in this Handbook. Operating costs for central systems with airport boilers are calculated using an average cost rate for electricity ($/KWh) and natural gas ($/mmBtu) as presented in Table 16; total electricity consumption per year (KWh/yr) data; total heat energy consumption per year (mmBtu/yr) data; and information regarding the anticipated useful life of the equipment. Central system electricity-related operating cost Total electric energy consumption,= KWh yr cost of electricity, $ KWh number ( ) × ( ) × of years equipment used( ) For operating costs associated with the airport boiler(s), the following equation is used to calculate operating costs: Central system boiler-related operating cost Total heat energy consumption,mmBTU yr= ( ) × ( ) × cost of natural gas, $ mmBTU number of years equipment used( ) Then the total operating cost is simply the sum of these two costs: Central system operating cost Central syste= melectricity-related operating cost $ C ( ) + entral system boiler-related operating cost $( )

Quantitative assessments 59 Similar to capital costs, these calculations can be performed for each of the aircraft categories if cost per category is necessary. Otherwise, the total electric energy and total heat energy con- sumptions for all aircraft categories can be used. To calculate maintenance costs, the total number of gates across all aircraft types is used as follows: Central systemmaintenance cost Total numbe= r of gates Central systemmaintenance co ( ) × st, $ gate-yr number of years equipment u ( ) × sed( ) As indicated in Table 21, the lowest number of gates shown is eight. This is to indicate that central systems should not be used to support fewer than eight gates, as POU systems would be more cost effective. Finally, the total cost is simply the addition of the cost components: Total central system cost Central system ca= pital cost Central system electricity-re ( ) + lated operating cost Central system boil ( ) + er-related operating cost Central system ( ) + maintenance cost( ) As previously explained, these costs can be modified as necessary to reflect present day values using a suitable inflation rate such as two percent. 3.3.3.4 Example Calculations The example calculations are based on the use of the example and default data presented in this chapter and assuming a 15-year usage period. Assuming the number of LTO cycles/yr and gates are specified as in Table 14, the central system capital cost for the narrow body aircraft category is: Central system capital cost $52,741 gate $22= + 8,283 gate 12 gates $3,372,297 ( )× ( ) = These calculations are repeated for each of the other aircraft categories resulting in the final values presented in Table 24. Operating costs are calculated using the total electric energy and heat energy consumption data developed from the emissions calculations as presented in Figures 27 and 28. Aircraft Category Capital Cost ($) Narrow Body $3,372,297 Wide Body $396,272 Jumbo-Wide Body $3,236,608 Regional Jet $4,232,297 Turbo Prop $705,383 TOTAL = $11,942,857 Table 24. Central system with airport boiler capital costs—example calculations.

60 handbook for evaluating emissions and Costs of apUs and alternative Systems The operating cost for the narrow body aircraft category is: Narrow body aircraft category electric energy consumption 468.224MWh/yr 468,224 KWh = = /yr (Note: 1MWh= 1,000 KWh) Central system electricity-related operating cost 468,224 KWh yr $0.07 KWh 15 years = ( ) × ( ) × ( ) = $491,635 Narrow body aircraft category heat energy consumption 397.761mmBTU yr Cent = ral system boiler-related operating cost 3= 97.761mmBTU yr $4 mmBTU 15 years $23, ( )× ( )× ( ) = 866 These calculations are conducted for each aircraft category and then summed as shown in Tables 25 and 26. As with the emissions calculations, these costs represent average weighted values because the electric and heat energy consumption values account for the distribution of ambient conditions (i.e., 25% cold, 50% neutral, and 25% hot). For maintenance costs, the total number of gates (38) shown in Table 14 is used to interpolate for the maintenance cost rate in Table 21: 30 2,636 38 ? 40 2,615 Figure 27. Sample electric energy consumption data—central system with airport boiler. Figure 28. Sample heat energy consumption data—central system with airport boiler.

Quantitative assessments 61 Central systemmaintenance cost rate for 38 gates 38 30 40 30 2,615 2,636= − −   × −( ) + = 2,636 $2,619.2 gate-yr Then the maintenance cost is calculated as: Central systemmaintenance cost 38 gates= ( )× $2,619.2 gate-yr 15 years $1,492,944 ( )× ( ) = The total cost is calculated as: Total Central systemwith airport boiler cost $11,942,857 $1,127,255 $43,918 $1,492,9 = + + + 44 $14,606,974= 3.4 Results Comparisons The calculated fuel/energy consumption, emissions, and costs by themselves can be useful in providing rough estimates that can be used for planning purposes. The usefulness of these results needs to be considered in light of their accuracy level, which can generally be described as Aircraft Category Electricity-related Operating Cost ($) Narrow Body $491,635 Wide Body $48,073 Jumbo-Wide Body $102,163 Regional Jet $410,569 Turbo Prop $74,815 TOTAL = $1,127,255 SOURCE: ASE, 2011. Table 25. Electricity-related operating cost—example calculations. Aircraft Category Boiler-related Operating Cost ($) Narrow Body $23,866 Wide Body $2,402 Jumbo-Wide Body $4,705 Regional Jet $11,969 Turbo Prop $977 TOTAL = $43,918 SOURCE: ASE, 2011. Table 26. Boiler-related operating cost—example calculations.

62 handbook for evaluating emissions and Costs of apUs and alternative Systems an order-of-magnitude. As such, their usefulness increases when they are compared (i.e., com- parison of results from different scenarios). Comparisons must be carefully conducted to make sure only like items are compared under the same timeframes. In comparing fuel/energy consumption and emissions between APUs and alternative sys- tems (including between different alternative systems), two issues need to be addressed. First, although different timeframes or periods can be used, it is recommended as part of this Hand- book to compare results on a yearly basis (e.g., emissions inventory for a year). Second, since the APU is commonly used during the “APU Start” and “Main Engine Start” modes even when alternative systems are available, the fuel consumption and emissions for those two modes will cancel out as illustrated in Figure 29. Third, as explained in Chapter 2, it should be understood that direct emissions from APUs occurring “locally” at the airport have different impacts than the indirect emissions occurring from the generation of electricity at power plants that are outside of the airport boundary. In this case, only the APU emissions are assumed to have an impact on local airport air quality while the power plant emissions are assumed to have no direct impact on local air quality in the vicin- ity of the airport. Criteria pollutant emissions from power plants are generally only accounted for in a detailed life-cycle assessment, and greenhouse gas emissions associated with electricity generation are categorized as indirect emissions within an airport emissions inventory. The user needs to be cognizant of these differences in order to properly consider their importance in planning decisions. For comparisons involving costs, there are also three issues to consider. First, the timeframes for costs (i.e., operating and maintenance) should generally be conducted on an expected life- cycle basis (e.g., 15 years). Although only one life-cycle number of years can be used in a single set of cost calculations, it is recommended that the user evaluate other equipment life cycles (e.g., 5 years, 10 years, 15 years, etc.) to understand cost differences between the different alternative systems. Figure 29. Comparison of emissions— APU vs. central system with airport boiler.

Quantitative assessments 63 Second, although total costs for alternative systems can be compared, it is recommended that capital, operating, and maintenance cost estimates be preserved and compared to allow a greater understanding of the factors that influence total costs. This may also allow the user to identify better strategies in terms of using existing financial resources to implement alternative systems. Third, the costs can be adjusted for inflation and other economic factors. The 2010 dollar- based costs data provided in the Handbook for each alternative system allow “apples-to-apples” comparisons, but the advanced user may wish to make adjustments to the cost data to evaluate the effects on total costs associated with different acquisition/payment strategies (e.g., lump sum payment vs. long-term financing).