Aviation: technologies and fuels to support climate ambitions towards 2050

Report no. 5/23: In 2019, the aviation sector directly employed 11.3 million people worldwide. If also accounting for the associated indirect, induced, and catalytic jobs, aviation enabled a total of 87.7 million jobs, which translates into a gross world product of $3,500 billion (ATAG, 2020): equivalent to a national GDP level between that of the UK and Germany. Yet, aviation is more than can be expressed by sober economic statistics. It is a lifeline for countries that almost entirely depend upon tourism, an enabler of international trade, and an icon of technological progress, globalisation, and prosperity.

However, in order to generate these benefits, in 2019, the global aviation industry consumed around 363 billion litres of jet fuel and was responsible for 914 MtCO₂ in direct emissions (IATA, 2020). Passenger aviation, including aircraft carrying belly freight, accounted for 92% of these emissions, with the remaining 8% being attributable to freighter flights (ICCT, 2020). If future fuel use and emissions growth is only half the historical (1980-2019) rate of 2.8% per year, global aviation fuel demand and CO₂ emissions would increase by around 50% by 2050.

Such growth would be in stark contrast to what is needed to mitigate climate change. The Paris Agreement calls for limiting the rise in mean global temperature to well below 2°C above pre-industrial levels, and preferably limiting the increase to 1.5°C. This target requires achieving net-zero greenhouse gas emissions by 2050 which can only be achieved with a significant contribution from aviation. Already in 2009, IATA, the aviation industry’s trade body, set a sector target of reducing CO₂ emissions by 50% over 2005 levels by 2050, and has recently updated this ambition to net zero CO₂ by 2050 (IATA, 2022). In the meantime, individual airlines have started to set their own net-zero CO₂ emissions goals by 2050.

Whereas more modest reductions could continue to be realized by incremental improvements, as during the past five decades, such drastic abatement requires a radical transformation of the entire aviation sector, affecting each determinant of CO₂ emissions. This report illustrates how such strong reductions could be achieved, along with the implications for stakeholders of the aviation value chain, particularly the fuels industry.

A number of different analyses have been published in recent years that explore the opportunities and challenges of global aviation deep decarbonization. Other studies taking a global view include ATAG (2021) and Shell (2021). In addition, NLR (2021) took a European perspective, whereas Sustainable Aviation (2020) focussed on the UK. Common to all studies is the goal of complete sector decarbonization by 2050 and the understanding that there is no silver bullet for satisfying this objective; rather all factors affecting CO₂ emissions reduction need to be exploited, i.e., aircraft fuel efficiency improvements, advancements in air traffic control and aircraft operations, low-carbon aviation fuels, demand reductions as a result of introducing more expensive aviation fuels or as a consequence of carbon taxes, and offsets.

This study differs from others in several ways:
Transparent, integrated modelling of the global aviation system down to an individual flight itinerary level, considering regional differences and system feedbacks such as the (demand-related) rebound effect.
Transparent aircraft deployment pathways, considering emerging technologies and related time constants (described in detail in the appendices to this report), 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

This report is structured as follows. Section 2 describes key aviation sector characteristics which are critical to understanding the challenges the industry faces when trying to strongly reduce CO₂ emissions. Section 3 explores options for reducing CO₂ emissions, including aircraft technology-related efficiency improvements and alternative aviation fuels. Section 4 introduces the modelling methodology for a global aviation systems model (AIM), which is used to project what would be required to achieve future aviation CO₂ emissions targets under a range of scenarios, and the characteristics of the technologies and fuels that are used as modelling inputs. Modelling outcomes are presented in Section 5 discussed in Section 6, and a summary of conclusions is given in Section 7.

Additional supporting material for this study, discussing modelling assumptions in more detail and providing additional results, is also available in the report appendices.