The EU Emission Trading System is evolving to address non- CO2 emissions, including those from the aviation sector: from 2025, it aims to incorporate emissions such as nitrogen oxides (NOx), particulate matter and water vapour.retrospectively and flights departing from the EU to destinations outside the European Economic Area (EEA) are not covered by the scheme – apart from the United Kingdom and Switzerland. The EU ETS is evolving to address non-CO2 emissions, including those from the aviation sector: from 2025, it aims to incorporate emissions such as nitrogen oxides (NOx), particulate matter and water vapour into its framework.58 The inclusion of non- CO2 emissions will require airlines to monitor and report these emissions for each flight. Many airlines claim this adds regulatory pressure and leads to compliance costs and operational adjustments, although European carriers flying predominantly short-haul and other industry stakeholders welcomed this development.59 An increased focus on non-CO2 emissions and contrails has been a theme of 2024, which saw a flurry of activities and trials in this area. Several airlines have been testing and optimizing flight planning and airspace management to reduce the formation of contrails, using AI and optimization software to help select more fuel-efficient routes and altitudes.60 Many respondents expect trials to continue in 2025, while expressing cautious optimism around the impacts, given the scientific uncertainty surrounding these issues. Research into this area is continuing: one of the latest studies from the Whittle Laboratory at the University of Cambridge highlights how the implementation of a global contrail avoidance system could reduce the warming effect of aviation by 50-85% by 2050.61 Geographic concentration of feedstock resources As of 2024, the vast majority of SAF being produced or developed is HEFA, with increasing interest in alcohol-to-jet following the inauguration of the first commercial-scale refinery by LanzaJet in 2024. SAF production is therefore highly dependent on bio-feedstock and trades. This report has already discussed how markets in Asia and South America benefit from access to higher volumes of feedstocks and lower costs, while other markets, including the US and Europe, have developed greater dependency on imported low-cost feedstocks (see section above). China has been the world’s largest supplier of used cooking oil, with peak exports in November 2024, due to a sharp increase in shipments to Europe and the US. Following updated 45Z guidance, market experts consulted for this report expect trade flows to be diverted from the US to Europe, although the Chinese government’s removal of the 13% tax rebate on exports is expected to create volatility. On a similar note, in 2024, Indonesia restricted exports of palm oil mill effluent and used cooking oil, to favour domestic use ahead of an increased B40 biodiesel blending mandate and a tighter approval process for exports announced in 2025.62 Executives interviewed believe recent feedstock trades and policies are opening up an opportunity for alternative feedstocks or other countries to step in. Latin America is a natural candidate, with Brazil holding notable volumes of soybean (HEFA feedstock) and sugarcane (AtJ feedstock). According to market experts consulted for this report, trades of tallow, which could potentially lead to fuels with a lower carbon intensity than used cooking oil, may also face an increase in 2025, although much of this is likely to be used for renewable road transport fuel rather than aviation. Meanwhile, China has been increasing its global share of ethanol production for use in road transport, reaching approximately 4.9 billion litres in 2024. Renewable diesel refinery capacity in China is currently limited, but it could be temporarily boosted and subsequently repurposed for SAF if and when demand for road transport fuels decreases. However, new SAF facilities will most likely be needed to achieve scale, further exacerbating changes in feedstock value chains. Amid an increasingly complex trade and geopolitical context, experts interviewed are confident that, during 2025, regions such as Europe may have to explore loosening feedstock eligibility criteria to accommodate a wider pool of imports, or look at greater domestic production of feedstocks, such as cover crops. These decisions will come with sustainability trade-offs (discussed in the following section) and will need to be assessed alongside anti-dumping concerns, already the focus of a European investigation in 2024.63 As SAF scales, ensuring its integrity is paramount – without robust safeguards, sustainability risks could undermine its potential. RSB’s recent work in Southeast Asia highlights how strong sustainability standards, particularly around feedstock traceability and land-use protections, provide a clear path forward for responsible SAF expansion. In 2025, we will continue driving solutions that protect ecosystems, foster transparency and build confidence in truly sustainable SAF, while also ensuring it supports economic resilience, strengthens rural livelihoods and secures long-term decarbonization. Elena Schmidt, Executive Director, Roundtable on Sustainable Biomaterials (RSB) Global Aviation Sustainability Outlook 2025 24