Tammy Klein of Transport Energy Strategies published an analysis on 1 December 2025 with a sharp diagnosis of where the global Sustainable Aviation Fuel (SAF) market actually stands. We are summarising it here with her permission because it cuts through a lot of the noise around aviation defossilisation. Her conclusion in one line: technology is not the binding constraint. Policy design is.
The pattern that keeps repeating
Klein’s analysis, drawn from a recent client report, identifies a consistent pattern across every major SAF market. Regions that pair demand certainty (blending mandates) with credible long-term revenue support (price mechanisms, contracts for difference, stable offtake frameworks) attract capital and bring projects to financial close. Regions that rely on short-duration incentives, tax credits with expiration risk, or incomplete policy frameworks do not – even when their technical potential is excellent.
The result is what she describes as an increasingly uneven global landscape: some regions may scale beyond HEFA (waste-lipid-based SAF) into Fischer-Tropsch, alcohol-to-jet and Power-to-Liquid pathways; others will struggle to secure even modest HEFA volumes.
Region by region
European Union. Strong demand signal through the ReFuelEU Aviation mandate, but the revenue support mechanism is missing. The mandate creates compliance obligations without giving developers the predictability needed for first-of-a-kind synthetic fuel projects. Europe is expected to meet early blending targets through imported HEFA, but its synthetic sub-targets face real risk because the financing case for e-SAF projects has not closed.
United Kingdom. The same demand signal as the EU, plus a revenue support mechanism under development. This pairing is what attracts capital. The UK is positioned to advance further than the EU on advanced pathways for this reason alone.
United States. Strong technical potential but heavy reliance on tax credits and state-level clean fuel programmes such as California’s Low Carbon Fuel Standard. These instruments operate on short timelines, with expiration risk, fluctuating credit values, and – in the current US political climate – no assurance that incentives will remain aligned with project lifecycles. Investor confidence is rated low to moderate despite the underlying capability.
Singapore, China. Progressing because the state role reduces financing uncertainty. Singapore is moving fastest, having positioned itself as a regional hub.
Brazil. Significant feedstock advantages but lacks binding domestic demand. Investment follows policy structure rather than policy ambition.
What this means for advanced pathways
Klein’s central forecast is that SAF will grow through 2030 but remain dominated by HEFA. Waste lipids are the only feedstock that can scale under current financing conditions. The advanced pathways – Fischer-Tropsch from biomass or solid waste, alcohol-to-jet, and Power-to-Liquid – will move only when governments create long-duration price signals that share risk with developers.
This is an important framing for everyone working on Power-to-X. The technical feasibility of e-SAF is no longer the open question. Multiple demonstration plants are operating, RFNBO certification is now available for sites inside and outside the EU (see our recent post on HIF Global’s Haru Oni certification), and the engineering challenges are well-characterised. What is missing is the offtake-price-equivalent that lets a developer close a project finance round.
The next two to three years
Klein argues that the next 24 to 36 months will determine whether the SAF sector becomes a true multi-pathway, multi-feedstock market – or stays locked into a HEFA-dominated supply base that cannot meet long-term blending targets. The differentiator will not be technological readiness. It will be which jurisdictions align mandates with revenue stability, and which jurisdictions do not.
SPIN Perspective
Klein’s analysis aligns with what the Swiss Power-to-X community has been observing for some time. The cancellation of Shell’s Rotterdam biofuels plant in September 2025 (see our analysis) was a concrete demonstration of the same point: a mandate-driven demand signal without matching production-side support does not, by itself, underwrite multi-billion-dollar production capacity.
For Switzerland specifically, the policy implication is two-fold. First, as an importing market we should pay close attention to which export-oriented producers – in regions like Patagonia, the Iberian Peninsula, North Africa, or Norway – actually achieve commercial scale, because those will determine what RFNBO supply Switzerland can access. Second, as a country with significant engineering, equipment and finance capacity in the Power-to-X value chain, we have an interest in advocating for European policy frameworks that get e-SAF projects to financial close – not just for environmental reasons, but because Swiss firms are well positioned to supply the projects that result.
Honest pessimism about policy design is more useful right now than optimistic talk about technology. Klein’s piece is worth reading in full.
Source: Tammy Klein, “SAF at a Crossroads: Why Policy Design Will Decide the Next Decade”, Transport Energy Strategies, 1 December 2025. Summarised with the author’s permission.