1 Diplomarbeit Studiendepartment Fahrzeugtechnik und Flugzeugbau Identifying CO2 Reducing Aircraft Technologies and Estimating their Impact on Global Emissions Arno Apffelstaedt 08. Juli 2009 2 Hochschule für Angewandte Wissenschaften Hamburg Fakultät Technik und Informatik Department Fahrzeugtechnik + Flugzeugbau Berliner Tor 9 20099 Hamburg in Zusammenarbeit mit: Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR) Institut für Lufttransportkonzepte & Technologiebewertung Blohmstraße 18 21079 Hamburg Verfasser: Arno Apffelstaedt Abgabedatum: 08.07.2009 1. Prüfer: Prof. Dr. Dieter Scholz, MSME 2. Prüfer: Dr.-Ing. Eike Stumpf Industrielle Betreuung: Dr.-Ing. Eike Stumpf 3 Abstract The strong growth in worldwide air traffic has raised concern on aviation’s impact on climate change. According to latest scientific estimates, carbon dioxide is one of the main contributors of aviation to global warming, accounting for up to the half of its entire positive radiative forcing. As a reaction to these findings, there is an increased interest among the industry, scientific community and governments in possible approaches to mitigating the carbon footprint of aviation. Aircraft CO2 emission is set by six technological key parameters, which define the range, the engine’s efficiency, the aircraft’s efficiency in terms of aerodynamics and weight, and the fuel efficiency in terms of heat content and fuel-specific CO2 emission. A parametric study on the single influence of the parameters is conducted, which gives engine efficiency, fuel heat content and the zero-lift drag coefficient as the most powerful technological levers. Future aircraft technologies are identified through a literature study. Some of the most promising concepts for a medium-term application are found to be laminar flow technologies, geared and open rotor engine architectures, new materials for primary structures and bio-fuels. A method is developed and applied to assess the future fleet built-up through 2036. New aircraft programs as well as phase-out of in-service aircraft are considered. Individual aircraft’s projected fuel efficiency and operational characteristics are introduced to assess the overall fleet’s CO2 emission development over the considered time frame. Three scenarios are established to simulate different future rates of technology progress and thus the possible implementation of identified technologies on future aircraft. Besides the individual aircraft‘s technological advances, further measures to reduce CO2 emissions on a fleet level are analyzed: Bio fuels, shorter aircraft program cycles and shorter aircraft life. It is shown that the sole aircraft-related technology improvements will not be sufficient to reach such goals as ‘carbon neutral growth’ due to a constantly high traffic growth rate. Bio fuels seem to be the only solution for this problem, however, this technology is still immature and thus subject of high uncertainty in terms of economic viability as well as net-carbon footprint. 4 DEPARTMENT FAHRZEUGTECHNIK UND FLUGZEUBAU Identifying CO2 Reducing Aircraft Technologies and Estimating their Impact on Global Emissions Aufgabenstellung zur Diplomarbeit gemäß Prüfungsordnung Background European aeronautic research is driven by the ambitious goals of the Advisory Council for Aeronautics Research in Europe (ACARE) and its Vision 2020: A 50% reduction in aeronautic-related CO2 emission in Europe is envisaged for 2020. The International Air Transport Association (IATA) has expanded this goal into a long-term global request for carbon-neutral air traffic by 2050. As a first step a technology roadmap is set up by international experts from industry and academia in a project organized by IATA. Generally speaking there exists a broad range of "technologies" that can be applied to reduce CO2 emissions. On the one hand CO2 emissions are influenced by the aircraft configuration and detailed design considerations. On the other hand it is of importance how aircraft are operated in the aviation system. Task A comprehensive listing of potential technologies for CO2 reduction has to be set up and the global impact of the identified new technologies needs to be estimated. This review can be based on literature, the internet, and interviews with experts in the field. These inputs are then taken to estimate the global CO2 reduction potential of the technologies based on aviation data bases, handbook methods and simple own models. 1. Parametric Assessment: • Definition of the influencing physical variables which set the fuel consumption and CO2 production of an aircraft. • Formulation of an evaluation function suitable to measure the influence of these variables on fuel and CO2 efficiency. • Parametric application of the defined target function to assess the impact of each variable with regard to its physical constraints. 2. Technology Survey: • Identification of current developments and possible future technologies with potential to reduce CO2 emissions. • Literature research on the technologies’ potential to reduce CO2 emissions and the timeline to be available for commercial aviation. 5 3. Fleet Forecast: • Identification of the current world fleet composition, fuel consumption and CO2 emissions. • Estimation of the fuel consumption and CO2 production of future aircraft equipped with new technology from the technology survey. • Estimation of the future world fleet composition using generally acknowledged assumptions concerning growth rates, production rates and aircraft utilization cycles. • Estimation of the future world fleet fuel consumption and CO2 emissions. The report has to be written in English based on German or international standards on report writing. The thesis is supervised at the Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR) in Hamburg. Support is given by Dr.-Ing. Eike Stumpf. 6 Statutory Declaration “I declare in lieu of an oath that I have written this diploma thesis myself and that I have not used any sources or resources other than stated for its preparation. I further declare that I have clearly indicated all direct and indirect quotations. This diploma thesis has not been submitted elsewhere for examination purposes.” July, 8th 2009 Arno Apffelstaedt 7 Content Abstract ............................................................................................................................. 3 Statutory Declaration .................................................................................................................. 6 List of Figures ............................................................................................................................. 9 List of Tables ........................................................................................................................... 12 Nomenclature ........................................................................................................................... 14 Abbreviations ........................................................................................................................... 16 1 Introduction ..................................................................................................... 19 1.1 Background and Motivation ............................................................................. 19 1.2 Goals and Objectives ........................................................................................ 21 1.3 Methodology ..................................................................................................... 21 1.4 Organization of the Thesis ................................................................................ 22 2 Theory: Understanding Aircraft CO2 Emission .......................................... 24 2.1 Sources and Consequences of Aviation Emissions .......................................... 24 2.2 The Influence of Aircraft Operation and Technology on CO2 Emissions ........ 29 2.3 Chapter Summary ............................................................................................. 38 3 Parametric Study ............................................................................................ 39 3.1 Estimating Fuel Burn and CO2 Emissions ........................................................ 39 3.2 Reference Aircraft ............................................................................................. 47 3.3 Methodology to Calculate Parametric Influence .............................................. 53 3.4 Results ............................................................................................................... 57 3.5 Analysis and Interpretation of Results .............................................................. 60 3.6 Chapter Summary ............................................................................................. 67 4 Technology Survey .......................................................................................... 68 4.1 Aerodynamics ................................................................................................... 68 4.2 Aircraft Engines and Secondary Power ............................................................ 80 4.3 Aircraft Empty Weight ..................................................................................... 93 4.4 Alternative Fuels ............................................................................................... 97 4.5 Air Traffic Management ................................................................................. 105 4.6 Chapter Summary ..........................................................................................