The National Academies

ACRP 02-25 [Final]

Evaluating Alternatives For Aircraft Ground Power, Heating, and Air Conditioning

  Project Data
Funds: $200,000
Research Agency: Environmental Science Associates
Principal Investigator: Brian Kim
Effective Date: 7/6/2010
Completion Date: 8/6/2011


Air quality (and specifically emissions) is an emerging issue that is beginning to affect airports and airlines. As such, airports are looking at alternatives for their own operations as well as for the airlines serving their airports. Aircraft auxiliary power units (APUs) are a source of emissions and noise; however, there are alternatives to APUs that provide ground power, heating, and air conditioning. These alternatives can be mobile units, terminal based, bridge based, or ramp based. Each of these alternatives has different capital and operating costs, as well as different effects on emissions. What works at one airport may not be applicable at another airport for various reasons such as different climate conditions, airline aircraft fleet, and terminal and ramp infrastructure. While airports are familiar with the range of alternatives to aircraft APUs, information is needed on their environmental benefits and other considerations (e.g., costs, funding, operational impacts, and maintenance) for selecting and implementing alternatives.  Research is needed to provide such information to assist airports and airlines in evaluating APU alternatives.
The objective of this research is to prepare a workbook for airport, airline, and environmental planners that can be used to evaluate alternatives to aircraft auxiliary power units (APUs) for power, heating, and air conditioning. The workbook should include tools to quantify the general emissions benefits of alternatives and to provide appropriate quantitative and/or qualitative analyses of the financial (e.g., capital, operating, and maintenance expenses) and operational implications, as well as any potential noise reductions that may occur. The workbook is intended to be a set of tools that will provide general emission information for various types of APUs, options, costs, and other considerations that can be applied.  
(1).  Develop a data-collection plan to (1) identify the most commonly used APUs for each type of commercial service aircraft, including turbo-prop, regional jet, narrow body, and wide body and (2) identify the alternatives to aircraft auxiliary power in use today for ground power, heating, and air conditioning by type (e.g., mobile and terminal-, ramp-, and bridge-based units). Alternatives should be appropriate to accommodate APU-equipped commercial service aircraft (including turbo-prop, regional jet, narrow body, and wide body) and should include industry-accepted equipment currently on the market.  (2). Conduct the approved data-collection plan. (3).  Prepare a working paper that recommends and justifies one representative baseline aircraft APU for each type of commercial service aircraft, and at least one representative for each type of alternative (e.g., mobile and terminal-, ramp-, and bridge-based) for each aircraft type that will be used in subsequent analysis. The selection criteria used to determine the representative baseline aircraft APU for each type of aircraft may include the number of APUs currently in service and the availability of emissions data. The selection criteria for the alternative(s) can be limited to industry-accepted, readily available, on-the-market equipment, and the ability to gather emissions data as appropriate.(4). Based on available data, quantify the average quarter-hour emission (i.e., CO, CO2, hydrocarbons, and NOx) and fuel burn for each identified baseline aircraft APU and alternative(s) approved in Task 3, for three climate conditions: 30ºF, 60ºF, and 90ºF. Under the 30º scenario, assume that no cooling is required; under the 60º scenario, assume that service is limited to just ground power, and for the 90º scenario, assume that heating is not required. For quantification of the alternative(s) that require electricity, the U.S. average emissions for electric generation and transmission should be used. (5). Provide a matrix or set of matrices comparing the baseline aircraft APU with the alternatives for each aircraft type and each climate scenario. In addition to the matrix, prepare a working paper that describes notable findings and observations in the matrix.(6). Conduct an appropriate quantitative and/or qualitative analysis of the financial and operational considerations for each type of alternative. This analysis should include an assessment and brief description of each alternative as it relates to design, infrastructure, capital costs, funding opportunities, operating and maintenance expenses, noise, cost allocation to airlines (including sub-metering), and considerations for obtaining local and corporate airline acceptance to ensure utilization of the alternative. Prepare a working paper providing the results of this analysis, a detailed outline of the workbook, and a description of the proposed tools. (7).  Prepare the workbook and the associated tools that airports can use to conduct an assessment of the use of alternatives to aircraft APUs based on the quantitative and qualitative analyses conducted in Tasks 4 and 6. The workbook should include instructions and a glossary.  Tools should include worksheets, checklists, and/or decision tree(s). Prepare a plan to conduct the Task 8 test application and validation of the workbook and associated tools at an airport.(8). Using the workbook and tools developed in Task 7, conduct a test application and validation to determine the applicability of the workbook and tools at an airport.   (9). Prepare a revised version of the workbook and tools based on feedback received in Task 8. Document comments received during the Task 8 field test and how they have been addressed in the final version of the workbook and tools. In addition, prepare a final report that documents the research effort, explains and justifies recommendations, and provides background information used in the development of the workbook. Prepare recommendations on further research in this subject area.

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