Decarbonisation Technology May 2025 Issue

producing, and scaling alternative low-carbon fuels and adopting these solutions throughout global supply chains and policies. As part of the European Union’s (EU) Renewable Energy Directive (RED), which sets targets for the EU’s renewable energy use and GHG reductions, the ReFuelEU Aviation Regulation focuses on reducing aviation’s carbon footprint and accelerating the transition to sustainable aviation practices, including blending targets for SAF. Beginning in 2025, at least 2% of all aviation fuel used within the EU must be SAF, gradually increasing to a minimum of 70% SAF in all EU airports by 2050 (EUR-Lex, 2023) . Additionally, the regulation sets specific sub-targets for the utilisation of synthetic aviation fuels derived from renewable hydrogen or captured carbon. Similarly, the FuelEU Maritime Regulation aims to promote renewable, low-carbon fuels and clean energy technologies for ships to reduce GHG intensity. This regulation stipulates that the GHG intensity limit should decrease by 2% starting in 2025, with more ambitious reductions planned for subsequent years, ultimately achieving an 80% reduction by 2050 (EUR-Lex, 2023) . From the global perspective, the International Civil Aviation Organization (ICAO) established the Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA), aiming to stabilise net CO₂ emissions from international aviation at 2020 levels. To achieve this, the framework sets rules for monitoring, reporting, and verifying emissions, with a system to offset emissions via the use of credits, CORSIA Eligible Units, or the usage of SAF, neutralising the environmental impact of international aviation growth. The International Maritime Organization (IMO) has established the IMO GHG Strategy, which aims to achieve net-zero GHG emissions from international shipping by 2050. According to projections from the Fourth IMO GHG Study, approximately 64% of the total CO₂ reduction in the shipping sector by 2050 is expected to come from the use of alternative low- or zero-carbon marine fuels ( IMO, 2020 ). Certification as a cornerstone for sustainable fuel production and traceability Sustainable fuels are defined by strict criteria that ensure their production is environmentally

SAF

AMF

IS C C EU

IS C C CORSIA ICAO CORSIA IS C C PLUS

RefuelEU A viation EU ETS FuelEU M ar i time UK ETS UK SAF M andate

Voluntary market SAF/AMF

converting waste oils and fats into SAF. Another rising process is alcohol-to-jet (AtJ), where alcohols such as ethanol and isobutanol are transformed into SAF. Drop-in AMFs include biofuels, e-fuels, and liquefied biogas (Bio- LNG). In contrast with SAF, non-drop-in AMFs, such as methanol, ammonia, and hydrogen, also play a crucial role in the sector. While these non-drop-in fuels offer greater long-term sustainability benefits, they involve significant investment in new technologies. Policies require both the adoption of alternative fuels and evidence that these fuels produce measurable sustainability outcomes. At the same time, market participants – ranging from producers to end consumers – increasingly seek transparency, accountability, and verified carbon footprint reductions throughout the supply chain. Rigorous certification systems like the International Sustainability & Carbon Certification (ISCC) confirm these standards are met. This article explores the role of certification in promoting the credibility of SAF and AMF, with a special focus on the ISCC Credit Transfer System (CTS), its structure, impact, and significance for stakeholders. The CTS enables the tracking and trading of SAF credits for verified carbon reductions within the voluntary market. From EU RED to CORSIA: policy-driven pathways to net-zero transport The aviation and maritime industries are considered among the most difficult to decarbonise due to their current heavy reliance on fossil fuels, each accounting for approximately 2-2.5% of global CO₂ emissions (IEA, 2025) (IEA, 2023) . Reducing emissions from these sectors requires developing, Figure 2 ISCC Certification schemes under which SAF and AMF can be certified (as of May 2025)