EU blending rules for sustainable aviation fuel set a rising minimum share at EU airports, starting with a 2% requirement and rising to at least 70% by 2050, and they require that by 2050 half of sustainable aviation fuel must be RFNBO electrofuels made from renewable hydrogen and captured carbon dioxide. As oil-market attention returns to energy security after the Iran war, a Chalmers University of Technology analysis finds the RFNBO definitions can drive higher demand for carbon dioxide from wood biomass combustion and favor combustion-based routes over wood gasification in synthetic fuel production.
The study examines synthetic methanol as a fuel molecule that can be converted into sustainable aviation fuel and compares three technically feasible pathways using biogenic carbon from residual material from the forest industry together with renewable hydrogen. Two pathways combust wood biomass, capture carbon dioxide from flue gases, and then combine the captured carbon dioxide with hydrogen produced separately using electricity.
The third pathway gasifies heated wood biomass into a synthesis gas containing carbon monoxide and hydrogen and uses it directly in methanol synthesis. The process also produces some carbon dioxide that can be converted into methanol with limited added hydrogen.
For combustion with carbon capture, the analysis lists a production cost of 1055 euros per tonne of methanol, electricity consumption of 1.8 megawatts of electricity per megawatt of methanol, and energy efficiency of approximately 37%. For combustion with carbon capture and simultaneous energy production, it lists a cost of 1495 euros per tonne, electricity consumption of 1.6 megawatts of electricity per megawatt of methanol, and energy efficiency of approximately 37%.
For wood biomass gasification, the analysis lists a cost of 820 euros per tonne of methanol, electricity consumption of 1.2 megawatts of electricity per megawatt of methanol, and energy efficiency of approximately 46%. The analysis also states the gasification pathway has up to 46% lower production cost and 30% lower electricity demand than the two combustion-based alternatives.
The analysis links the incentive difference to RFNBO eligibility rules. It states that RFNBO classification includes fuel from the combustion-based alternatives but excludes around half of the fuel produced via gasification because RFNBO fuels may not be produced using energy and carbon atoms that come directly from biomass, as they largely do in gasification-based production.
The paper states that meeting growing sustainable aviation fuel demand will require large-scale buildout of production capacity and long-lived investments. It also states RFNBOs are expected to expand from close to zero today to 35% of all aviation fuel in the EU by 2050.
