Technologies and fuels for decarbonising global aviation—the opportunities and challenges
This article provides a summary of a ‘deep dive’ study into the opportunities and challenges associated with the decarbonisation of the aviation industry. The study is part of Concawe’s Low Carbon Pathways project, and has been undertaken by E4tech (UK) in partnership with Air Transportation Analytics and Frontier Economics.
The characteristics of the study are:
- transparent, integrated modelling of the global aviation system down to an individual flight itinerary level, taking into account regional differences and system feedbacks such as the (demand-related) rebound effect;
- transparent aircraft deployment pathways, considering emerging technologies and related time constants, based on internally consistent assumptions;
- detailed bottom-up analysis of sustainable aviation fuel production pathway capacities; and
- a focus on implications for the fuels/refining industry.
The study describes the key aviation sector characteristics that are critical to understanding the challenges faced by the industry when trying to reduce CO₂ emissions. It explores options for reducing CO₂ emissions, including aircraft technology-related efficiency improvements and alternative aviation fuels. Finally, it introduces the modelling methodology, which is used to project what would be required to achieve future aviation CO₂ emissions targets under a range of scenarios (including technologies and fuels that are used as modelling inputs).
Any extra aircraft weight consumes additional fuel or—along with extra space—can generate revenue, and aviation depends heavily on high-density fuels per unit weight and volume. This stringent requirement rules out many alternative fuels, such as alcohols, due to their much lower gravimetric and volumetric energy densities compared to kerosene. Hence, this study does not consider all-electric aircraft: instead, the focus of the study is on drop-in sustainable aviation fuel (SAF) and liquid hydrogen as alternative aviation fuels.