Recent developments in the EU’s regulatory landscape for synthetic aviation fuels have ignited critical discussions around the efficiency and sustainability of the pathways endorsed for producing these fuels. A comprehensive study recently published by researchers at Chalmers University of Technology, Sweden, raises significant concerns about the unintended consequences embedded within the EU’s framework, particularly the mandatory integration of Renewable Fuels of Non-Biological Origin (RFNBOs). Their findings suggest that current EU policies may unintentionally promote less efficient production methods for synthetic methanol, a key precursor in sustainable aviation fuels, thereby jeopardizing both economic and environmental objectives.
The EU has been proactive in establishing binding requirements aimed at reducing reliance on fossil fuels within the aviation sector. A rule enforced from 2025 mandates that sustainable aviation fuels must constitute no less than 2% of all fuel at EU airports, increasing progressively to at least 70% by 2050. Importantly, half of this sustainable quota must be met through RFNBOs—synthetic fuels generated from renewable hydrogen and captured carbon dioxide. While this initiative is ambitious and grounded in mitigating aviation’s carbon footprint, the Chalmers study reveals that the regulatory emphasis on RFNBOs might not be driving innovation towards the most energy- and cost-efficient production pathways.
At the core of this issue lies the production of synthetic methanol, a compound versatile enough to function as a sustainable aviation fuel or a precursor for such fuels. The Chalmers research team undertook a computational simulation comparing three viable pathways, all harnessing biomass as the source of carbon atoms but differing fundamentally in their technological approaches. Two of these methods involved biomass combustion with subsequent carbon dioxide capture and hydrogen addition, while the third employed biomass gasification—where biomass is thermochemically transformed directly into synthesis gas—a mixture rich in carbon monoxide and hydrogen, which can then be converted into methanol.
From a technological standpoint, all three methodologies are capable of producing the same end product: methanol synthesized from renewable resources. However, the distinctions in their underlying processes carry significant implications for energy consumption, cost, and carbon efficiency. Biomass gasification emerged as the superior route overall, demonstrating roughly 46% lower production costs and a 30% reduction in electricity consumption compared to combustion-based techniques. This higher resource efficiency is attributed to the direct utilization of carbon in the form of synthesis gas, circumventing the energy losses inherent in converting biomass to carbon dioxide prior to methanol synthesis.
Despite these clear efficiency benefits, current EU policies favor combustion-based pathways under the RFNBO classification, largely excluding gasification-derived fuels. This dichotomy arises because RFNBO definitions prohibit the use of carbon atoms sourced directly from biomass, which is intrinsic to the gasification process. Instead, carbon from biomass is considered acceptable only if derived from carbon dioxide captured during biomass combustion, a condition that allows combustion-based fuels to qualify as RFNBOs. This regulatory nuance amplifies the demand for biomass-based carbon dioxide combustion residues, effectively disadvantaging the more efficient gasification pathway.
The ramifications of this regulatory bias are profound. Biomass is a finite and valuable resource, and its inefficient use threatens to undermine the very sustainability goals the EU seeks to advance. The combustion approach, particularly when coupled with carbon capture in combined heat and power (CHP) plants, not only incurs higher production costs but also consumes significantly more electrical energy per unit of methanol produced. This elevated energy demand can increase the overall carbon footprint if the electricity used is not sourced sustainably, posing a paradox where ‘renewable’ fuels contribute disproportionately to energy consumption.
Regulatory frameworks serve not only as guidelines but as strategic signals steering industry investment and innovation priorities. As Professor Henrik Thunman, a co-author of the study, explains, these policies risk locking the sector into suboptimal technological trajectories, hindering the adoption of resource-efficient solutions that could deliver better economic and environmental outcomes. This ‘lock-in’ effect could delay or diminish the impact of sustainable aviation strategies just as the global demand for sustainable fuels is set to soar.
This limitation is even more concerning considering the massive scale of infrastructure investments required to meet the EU’s sustainability ambitions. Thousands of production plants with long lifespans will be necessary worldwide, making it critical that the underlying technological choices are forward-looking and resilient against future regulatory changes. Investment decisions made under the current framework may inadvertently perpetuate less efficient systems, making the eventual transition to superior technologies more costly and difficult.
The study’s insights extend a compelling invitation to policymakers to recalibrate regulations, placing greater emphasis on fundamental energy and resource efficiency principles. Recognizing the tangible benefits of gasification—both in terms of energy use and cost-effectiveness—could enable a more balanced approach, one that leverages the complete spectrum of available technologies. Equally, integrating the potential of electrification in district heating systems and other synergies could further enhance overall system efficiency, addressing concerns that combustion pathways artificially make use of energy outputs like heat or electricity.
Moreover, the research underscores the importance of harmonizing climate ambitions with practical industrial feasibility. The current dissonance between regulatory definitions and energy system realities may stymie the growth of sustainable aviation fuel markets by imposing unnecessary constraints and fostering uncertainty among investors and researchers alike. Aligning regulatory frameworks with energy system fundamentals and resource efficiency criteria could catalyze technological progress and ensure rational investment planning, accelerating the transition to net-zero aviation.
The effects ripple beyond the borders of Europe, as international aviation is intrinsically global. The EU’s policy design could influence global standards, markets, and innovation trajectories. Consequently, refining the mandates around RFNBOs and their classification could have broad repercussions, potentially setting a precedent for other regions grappling with the challenges of decarbonizing aviation and industry. The study at Chalmers is therefore a vital contribution, highlighting the intricate interplay between policy, technology, and sustainability.
In conclusion, while the EU’s RefuelEU Aviation initiative marks a decisive step toward greener aviation fuels, emerging research reveals the need for nuanced policy adjustments. Current mandates risk incentivizing less energy- and cost-efficient production methods, which could decelerate progress toward climate targets. A re-evaluation of RFNBO definitions and regulatory frameworks, grounded in rigorous scientific analysis, holds the key to unlocking more sustainable pathways for synthetic aviation fuels, ensuring that Europe leads not only in ambition but in effective and efficient climate action.
Subject of Research: Not applicable
Article Title: Locked in on RFNBOs – Will EU mandates for drop-in synthetic aviation fuels lead to decreased energy- and cost-efficiency?
News Publication Date: 15-Feb-2026
Web References:
DOI: 10.1016/j.fuel.2025.137181
EU ReFuel Aviation Regulation
Definition of RFNBO
References:
Beiron, J., Harvey, S., & Thunman, H. (2026). Locked in on RFNBOs – Will EU mandates for drop-in synthetic aviation fuels lead to decreased energy- and cost-efficiency? Fuel. https://doi.org/10.1016/j.fuel.2025.137181
Image Credits: Gustavo Ramirez
Keywords
Sustainable aviation fuel, RFNBO, synthetic methanol, biomass gasification, EU regulations, energy efficiency, renewable hydrogen, carbon capture, combustion, aviation decarbonization, resource efficiency, RefuelEU Aviation
Tags: aviation fuel sustainability goalscarbon dioxide utilization for fuelscost implications of EU fuel policiesenergy efficiency in synthetic fuel productionenvironmental impact of aviation fuelsEU aviation sector decarbonizationEU binding sustainable fuel requirementsEU synthetic aviation fuel regulationsRenewable Fuels of Non-Biological Origin (RFNBOs)renewable hydrogen in aviation fuelsustainable aviation fuel mandates 2025synthetic methanol production challenges
