EU SAF Rules May Increase Costs, New Study Warns

New research from Chalmers University of Technology suggests the European Union's landmark ReFuelEU Aviation mandate may inadvertently increase costs and energy consumption for Sustainable Aviation Fuel (SAF). The study highlights how current regulations for RFNBO electrofuels (Renewable Fuel of Non-Biological Origin) penalize highly efficient production methods like biomass gasification in favor of more expensive alternatives.

The core issue identified is that the EU's rules could lock the aviation industry into less resource-efficient technologies, potentially raising airline operational costs and slowing the pace of decarbonization. This regulatory framework, while designed to ensure the environmental integrity of next-generation fuels, may have the unintended consequence of making the green transition more difficult and costly for both producers and consumers.

Background and Regulatory Framework

The EU's strategy for aviation decarbonization is anchored by Regulation (EU) 2023/2405, known as the ReFuelEU Aviation initiative. This regulation establishes progressively increasing mandates for fuel suppliers to blend SAF into the jet fuel available at EU airports. The targets are ambitious, culminating in a 70% SAF blend by 2050. Critically, half of that amount (35%) must be synthetic fuels, or RFNBOs, which are produced using renewable electricity and captured carbon dioxide in a process often called Power-to-Liquid (PtL).

The challenge arises from the strict criteria defined under the EU's Renewable Energy Directive for what qualifies as an RFNBO. The rules are designed to ensure that the carbon used in the fuel is genuinely 'additional' and not simply re-routed from existing biological cycles that have other uses. However, the Chalmers University study, published in the journal 'Fuel', found this definition creates a significant market distortion.

According to the research, only 55% of the fuel produced via the highly efficient biomass gasification pathway qualifies under the current RFNBO rules. This is because the process utilizes biogenic carbon directly from the biomass feedstock, which is disfavored by the regulation. In contrast, pathways involving combustion with carbon capture, which are less efficient, receive more favorable treatment. The European Commission's perspective is that these strict definitions are necessary to prevent the cannibalization of biogenic carbon needed for other hard-to-abate sectors, ensuring the integrity of the synthetic fuel program.

Technical Comparison: Production Pathways

The financial and energetic penalties of this regulatory choice are significant. The study provides a direct comparison between the two primary pathways for producing synthetic methanol, a precursor to synthetic jet fuel.

As the data shows, the gasification pathway is not only cheaper but also achieves a higher energy efficiency of 46%, compared to just 37% for combustion with carbon capture. This means it can produce more fuel from the same amount of initial energy and biomass feedstock.

Industry Impact and Historical Context

The implications of favoring the less efficient pathway are far-reaching. For European airlines like Lufthansa and Air France-KLM, this could translate to structurally higher fuel costs, which would likely be passed on to passengers through increased ticket prices. For SAF project developers, it creates investment uncertainty and the risk of stranded assets if they have already planned facilities based on the more efficient gasification technology.

This situation is not without precedent. In 2015, the EU was forced to revise its first-generation biofuel mandates after realizing they were causing Indirect Land Use Change (ILUC), where the demand for biofuel crops displaced food production and led to deforestation. That experience demonstrates how prescriptive renewable fuel mandates can have unintended negative consequences that require later legislative correction.

According to Henrik Thunman, Professor of Energy Technology at Chalmers University of Technology, the current rules risk locking the industry into suboptimal production methods instead of driving innovation. The industry is broadly shifting focus toward synthetic fuels to meet long-term mandates, as feedstocks for common biofuels like Hydroprocessed Esters and Fatty Acids (HEFA) are limited. An overview of various SAF pathways and challenges is maintained by the International Air Transport Association (IATA).

Technical Analysis

The findings suggest a fundamental tension within the EU's climate policy for aviation. By prescribing specific production pathways rather than adopting a performance-based standard that rewards the lowest lifecycle carbon intensity, the ReFuelEU mandate creates a market distortion. This approach prioritizes definitional purity over demonstrated resource efficiency, potentially leading to a more expensive and energy-intensive decarbonization trajectory. It stands in contrast to more flexible policies like the U.S. Inflation Reduction Act, which focuses on overall carbon intensity scores. The historical precedent with ILUC corrections suggests that such rigid, technology-prescriptive frameworks may prove unsustainable and require disruptive future adjustments as real-world production data reveals their inefficiencies.

What Comes Next

The ReFuelEU Aviation mandates are legally binding and will ramp up significantly in the coming years. Fuel suppliers at EU airports must adhere to the following confirmed milestones:

• By January 1, 2030, the fuel mix must contain at least 6% SAF, with a sub-mandate of 1.2% for synthetic aviation fuels (RFNBOs).
• By January 1, 2035, these figures rise to 20% total SAF and 5% synthetic fuels.

As these deadlines approach, the financial impact of the RFNBO definition will become more acute, likely intensifying the debate among policymakers, airlines, and fuel producers over whether the current rules should be revised to be more technology-neutral.

Why This Matters

The debate over SAF production rules is more than a technical dispute; it directly shapes the cost, speed, and resource efficiency of aviation's green transition. For airlines and passengers, it will influence the future price of air travel. For policymakers and the energy industry, it serves as a critical case study on the challenge of designing regulations that successfully drive innovation toward climate goals without imposing unintended economic and environmental penalties.