Sustainable Aviation Fuel (SAF) is no longer a concept of the future. It is rapidly becoming the cornerstone of global strategies aimed at decarbonising aviation. Yet, the trajectory of SAF implementation is deeply influenced by regulatory frameworks. A closer look at the UK, EU, and USA reveals a trio of distinct yet converging approaches that reflect their individual priorities, capabilities, and political will.
The United Kingdom’s Mandate-Driven Momentum
The UK has emerged as a frontrunner in legislating SAF usage. Central to its strategy is the SAF Mandate, a policy cornerstone that introduces progressively increasing blending requirements—from 2% in 2025 to 22% by 2040. This legislative push is backed by the Jet Zero Taskforce, which aligns cross-sector stakeholders toward a net-zero aviation vision by 2050.
Beyond mandates, the UK’s approach is layered with innovation incentives. A buy-out mechanism deters non-compliance, while the proposed Revenue Support Mechanism introduces price certainty for domestic producers. This is reinforced by initiatives such as the Advanced Fuels Fund and the UK SAF Clearing House, which are designed to overcome technical and financial barriers.
A unique element in the UK’s approach is its cap on HEFA (Hydro-processed Esters and Fatty Acids) and the gradual phasing in of Power-to-Liquid (PtL) obligations—signalling a long-term strategy to diversify sustainable feedstocks.
The European Union’s Harmonised Policy Architecture
The EU’s regulatory framework is arguably the most comprehensive, structured around the Renewable Energy Directives (RED I, II, and III) and the ReFuelEU Aviation Regulation. The latter introduces direct SAF blending mandates, beginning at 2% in 2025 and rising to 70% by 2050, with sub-targets for synthetic fuels.
Financial and market-based mechanisms underpin these regulations. The EU Emissions Trading System (ETS) now includes SAF-specific allowances, while the Innovation Fund, Horizon Europe, and InvestEU fuel SAF R&D and infrastructure deployment. A notable innovation is the prospective book-and-claim system, aimed at improving SAF market liquidity across member states.
Despite high ambitions, the EU is grappling with enforcement challenges and potential cost volatility. Still, its structured, cross-national approach provides a blueprint for harmonised SAF regulation.
The United States’ Incentive-Led Strategy
The U.S. has embraced a market-driven model, focusing on economic incentives rather than mandates. Federal support is anchored in tax credits introduced by the Inflation Reduction Act (IRA), especially the Section 45Z Clean Fuel Production Credit, which offers up to $1.75 per gallon of SAF. These are complemented by state-level programs like California’s Low Carbon Fuel Standard (LCFS), creating regional demand through tradable carbon credits.
The U.S. Department of Energy, Department of Defense, and FAA are further investing in SAF infrastructure and innovation through grant programs. However, with these incentives expiring in 2027, there are mounting calls for longer-term policy certainty to maintain momentum.
While less prescriptive, the U.S. model encourages innovation and diversity in feedstocks and production technologies. This flexibility could enable faster scaling if coupled with longer-term policy stability.
Comparative Insights: Divergent Roads to a Shared Destination
Each jurisdiction’s SAF framework reflects its regulatory culture. The UK’s model balances mandates with investment security, while the EU focuses on harmonised compliance and innovation. The U.S. leans heavily on economic incentives and market dynamics.
Despite these differences, shared themes emerge—such as the progressive blending targets, financial de-risking mechanisms, and growing interest in synthetic fuels. These commonalities could serve as a foundation for future international standardisation and mutual recognition of SAF certification systems.
Toward a Harmonised Future
As aviation seeks a net-zero future, aligning international SAF policies will be crucial. Policymakers and industry leaders must now look beyond borders, ensuring that regulatory frameworks not only drive national progress but also foster global scalability.
The evolution of SAF regulation in the UK, EU, and USA illustrates that while the paths differ, the goal remains universal: creating a resilient, low-carbon aviation sector. Sustainable flight depends not only on fuel innovation but also on regulatory vision.