WP4: Fuel operations and Impact on Environment


Lead: ONERA

Involved partners: EADS IW, DLR, CNRS, JAXA, UTokyo


Progress beyond the state of the art

Any new aircraft development integrates environmental issues: impact on environment shall be limited, and regulations will be more and more stringent. This is then a day-to-day concern with high-speed transport as well.

The impact of human activity on the environment is a very complex one to determine, all the more when dealing with emissions such as CO2, H2O, NOx and particles at high altitude, which is the main concern of high-speed transport. For example, a Mach 4-5 aircraft would have an optimized cruise altitude in the range 25 to 30 km. The impact of emissions and particles at such altitude where the atmosphere is more stratified, dryer, and where the mixing effects resulting from large scale transport and turbulence might deeply modify the mechanical and chemical processes that involve those products, has not been evaluated yet. As the long term impact on ozone layer and more generally on the climate might be different from the one from the same products emitted at a lower altitude by classic aircraft, HIKARI project intends to provide valuable knowledge on these issues.

Main Activities

Activities related to Environmental impact of fuel on ground process: The candidate fuels will be identified. They are basically liquefied hydrogen, liquefied methane, and liquid biofuel resulting from different production processes. The global cycle to produce, distribute, store these fuels will be analyzed, taking into account products and energy.

In particular, the energy required to liquefy the cryogenic fuels is a significant part of the total energy required to produce the fuel itself. Storing cryogenic fuels has also some impact on on-ground infrastructures. The environmental impact of these ground operations will be assessed. EADS IW will make a synthesis of the global environmental impact of these different fuels, using the data collected thanks to other past or running European or national programs, and merged with the Japanese similar existing results.

The outcome of this study will provide a database in order to enable a complete comparison and trade-off analysis of the global effect of fuel choice on environment to be performed within Task 4.2.

Activities related to Impact of emission of hypersonic aircraft on atmosphere and climate: The impact of different fleets of high speed aircraft on climate will be determined. This task will focus on particles, NOX, CO2 and H2O emissions and contrails formation during the flight, taking into account the flight profile which will bring the aircraft to a high altitude. ONERA will define the different scenarios regarding emissions of potential high speed aircraft (fleet size, fuel type, mission profile…). With these scenarios:

  • DLR will review and summarize previous existing results obtained through past programs (e.g. EU SCENIC and HISAC programs), NASA or IPCC studies.
  • CNRS will evaluate the global impact of aircraft emissions on atmospheric composition and climate, with a focus on H2O and NOx using LMDz-INCA model.
  • DLR will adapt its AirClim climate-chemistry-response model for high altitude operation, and will use it to evaluate the global impact of emissions on the long term climate on selected test cases in order to provide comparison with CNRS and UTokyo / JAXA results.
  • ONERA will also evaluate the consequences of water vapor emission and particles on contrails formation at high altitudes (up to 30km), and its elimination process in comparison with phenomena observed at lower altitude. Using existing results, DLR will also provide an estimation of the conventional air traffic which would have the same long term impact, in order to enable comparison between a potential hypersonic fleet and existing systems.
  • UTokyo and JAXA will:
    • Establish chemical analysis model for exhaust gas of hydrogen jet engines and high altitude atmosphere.
    • Conduct a sub-scale experiment to evaluate the chemical analysis model. This will be done by analyzing with Laser Induced Fluorescence (LIF) the behavior of H2/air combustion products when introduced in a vacuum chamber simulating high altitude conditions.
    • Estimate environmental impact of hydrogen jet engines with various equivalence ratios, simulating both ramjet and pre-cooled turbojet.

Expected Results

Each task of the present work package is expected to predict the impact of the emissions by a candidate high-speed aircraft on the climate, and to compare this effect with the impact of conventional subsonic aircraft. Different concepts will be considered covering a wide range of missions (e.g. range, altitude, trajectory, size of the fleet, type of fuel, etc.) in order to identify figures of merit for these different sizing parameters. The global effect of fuel choice will be addressed taking into account the production / distribution of the fuel, and in particular CO2 emission or consumption at ground level.

In general this work package is expected to provide an analysis of the impact of high altitude high speed flight emissions on the atmosphere on the long term evolution of the climate while taking into account production and distribution issues, as a function of the type of fuel.