Study: EU Regulations May Increase Costs and Energy Use for Synthetic Aviation Fuels

GOTHENBURG, Sweden – A new study from Chalmers University of Technology suggests that current EU regulations for sustainable aviation fuels (SAF) may inadvertently favor production methods that are more expensive and energy-intensive than available alternatives.

The research, published in the journal Fuel, analyzes different pathways for producing synthetic methanol—a precursor for fossil-free aviation fuel. The findings indicate that the EU’s “Renewable Fuel of Non-Biological Origin” (RFNBO) classification creates a regulatory “detour” that could hinder resource efficiency.

The RFNBO Mandate

Under the ReFuelEU Aviation regulations, airports must gradually increase the blend of sustainable fuels, reaching 70% by 2050. By that time, half of the SAF must qualify as RFNBOs—synthetic fuels produced from renewable hydrogen and captured carbon dioxide ($CO_2$).

However, the researchers argue that the strict definition of RFNBOs excludes some of the most efficient production methods.

Comparing Production Pathways

The study compared three methods of producing synthetic methanol using biomass and renewable electricity:

The analysis found that gasification—where biomass is converted directly into synthesis gas—is the most resource-efficient. Despite this, the RFNBO framework favors combustion-based pathways. This is because RFNBO rules generally prohibit using carbon atoms that come directly from biomass, requiring instead that $CO_2$ be captured after combustion.

Risk of “Lock-in” Effects

The researchers warn that these regulations may steer investments toward less efficient technologies. Because aviation fuel plants require long-term capital investment, choosing sub-optimal technology now could result in higher costs for decades.

“Instead of driving innovation towards the most efficient solutions, we risk locking ourselves into less resource-efficient production methods,” said Henrik Thunman, Professor of Energy Technology at Chalmers.

Policy Implications

The study highlights a potential contradiction in EU policy: while the RFNBO category aims to reduce reliance on limited biomass resources, the exclusion of efficient gasification may actually drive higher biomass demand due to the lower energy efficiency of the permitted combustion-based routes.

Johanna Beiron, the lead author of the study, noted that the current framework lacks alignment with fundamental energy principles. The research team suggests that adjusting these definitions could be necessary to ensure the aviation industry achieves climate targets without unnecessary economic and energy costs.