About the interaction between composition and performance of alternative jet fuels

Since the last decade, the aviation sector is looking for alternatives to kerosene derived from crude oil triggered also by commitments and policy packages, such as the ‘Flightpath 2050’ initiative and the comprehensive alternative fuels strategy, both released by the European Commission. An aircraft need with regard to a fuel is very strict, with severe constraints to ensure a safe and reliable operation for the whole flight envelope. When synthesizing a jet fuel from scratch, two important aspects need to be addressed: First, the safety aspect—the new fuel candidate must be certified, qualifying through several well-defined cost and time expensive tests, according to the approval protocol; secondly, the environmental aspect. Alternative aviation fuels alike Jet A-1 are composed of hydrocarbons; however, the amount and type of hydrocarbons (chemical family) differ considerably. The question is how the composition of the fuel will affect its suitability and performance: (i) thermo-physical and thermo-chemical properties of the new components to exclude any shortcomings with respect to performance and safety issues, and (ii) the new fuel combustion characteristics, i.e., ignition, flame speed, and emission pattern (pollutants), in particular. These issues are addressed in the present study. Thus, the road will be paved for developing a generalize science-based tool to investigate in an efficient way if a new fuel candidate may meet the fuel specifications.