The establishment of a new SAF research centre in Chengdu will have as its first task the definition of new standards and a Chinese certification system for sustainable fuel.2.3 Sustainability challenges Traceability and sustainability criteria for SAF feedstocks As global trades of feedstocks and fuels flourish and aviation’s reliance on SAF as a means to get to net zero increases, scrutiny of the sustainability credentials of these commodities is expected to intensify. Land-use changes, deforestation, poor agricultural practices, food security and biodiversity impacts are some of the potential concerns that have, in Europe at least, prompted investigations into the integrity of biofuel imports. This in turn has led to regulatory restrictions or bans on first-generation fuels derived from food crops, as well as caps on biofuels made from used cooking oil and animal fats. The risk of a supply-constrained scenario could exert positive pressure on the development of power-to-liquid or alternative SAF production pathways (e.g. gasification and Fischer-Tropsch). Equally, amid these concerns, some countries are moving towards improving transparency and research in this area. In 2024, the Roundtable for Sustainable Biomaterials published a comprehensive assessment of the SAF potential in Southeast Asia, identifying deforestation as the most significant risk in the region and recommending sustainable cultivation practices for food and feed crops to limit the risks of land- use change.64 Standards are helpful to assess these risks, although there are currently multiple methodologies employed globally. The EU’s Renewable Energy Directive (RED) II, ICAO’s CORSIA model and the US GREET (Greenhouse gases, Regulated Emissions, and Energy use in Technologies) model all calculate the lifecycle assessment as well as direct and indirect land-use changes in different ways. These methodologies may be updated periodically to reflect the latest evidence. For example, in April 2024 the US amended the GREET model to allow corn-to- ethanol to remain eligible for a lower carbon intensity value than in Europe, by introducing reductions for sustainable land management practices such as cover-cropping and no-till farming. Much of the debate in 2024 has revolved around accuracy and interactions between these standards and this is expected to increase further as China develops its own methodology. The establishment of a new SAF research centre in Chengdu will have as its first task the definition of new standards and a Chinese certification system for sustainable fuel. In September 2024, as methodologies multiplied, the IEA set out options for defining more consistent sustainability criteria for fuels across sectors and regions. The IEA’s report recognizes the need for a minimum emission threshold across fuels and stresses the benefit of a risk-based approach on indirect land- use change over quantitative modelling.65 Greenwashing and consumer scepticism Despite traceability of feedstocks featuring high on the list of priorities for 2025, especially as new markets look to move into SAF production, stakeholders interviewed for this report were not generally worried about the risk of greenwashing and how this could affect passengers’ perspectives on sustainability. However, this finding should be caveated, as the relative importance of the risk of greenwashing varies by stakeholder category and by region (e.g. acceptance of certain feedstocks or practices can be more stringent in certain regions). In emerging economies in particular, investors attending Airports of Tomorrow roundtables during 2024 repeatedly flagged concerns with investment in SAF production pathways or feedstocks that may not be universally recognized as sustainable. This heightens the need for more consistent sustainability criteria across countries, as well as alignment of national taxonomies, which can employ varying criteria to determine whether a certain aviation decarbonization investment or activity can be deemed sustainable or transitional. In 2024, the European Commission provided further guidance on the implementation of the EU Taxonomy,66 while Brazil started work on a new aviation taxonomy and the ASEAN Secretariat also launched a consultation process on the aviation sector. Feedstock risk, however, is only one of the factors used to determine how “sustainable” a fuel is – and how this information is communicated publicly can also affect the perception of greenwashing. In April 2024, concerns in Europe around greenwashing hit the news when the European Commission wrote to 20 airlines to investigate whether the climate projects those companies were undertaking and advertising as “green” or “carbon neutral” – as well as their wider claims of progress towards net-zero emissions – could be validated as such.67 Meanwhile, a Virgin Atlantic advertisement to celebrate “the first transatlantic flight powered by 100% sustainable aviation fuel” was banned, after the UK’s advertising watchdog deemed it “misleading”.68 A Dutch court made a similar ruling on previous KLM advertising campaigns.69 By contrast, a district court in the US dismissed a similar greenwashing lawsuit against United Airways in August 2024.70 Global Aviation Sustainability Outlook 2025 25