The Path to Sustainable Aviation

WHITE PAPER

7 April 2026

By Prof. Don MacElroy (Professor Emeritus in Chemical Engineering, University College Dublin, and Chairman of the NEG8 Carbon Advisory Board)

In the field of carbon emissions mitigation, aviation is one of the key hard-to-abate areas. Decarbonisation via direct electrification, particularly for long-haul flights, is not a practical option using batteries and this sector of the aviation industry must rely on the use of high-energy density jet fuels.

The last ten to twenty years have seen a surge in research and development of technologies towards producing man-made carbon-based high-energy density jet fuels. These products, more generally known as Sustainable Aviation Fuels (SAFs), are hydrocarbons which fall in the kerosene carbon range C₈-C₁₆.

Currently the technological development of SAFs has proceeded along two primary lines of action: bio-SAF and electro or e-SAF. The former relates to using bio-resources including cooking and plant oils (leading to hydro-processed esters and fatty acids (HEFA)), agricultural waste, municipal solid waste, woody biomass and dedicated energy crops. A fundamental requirement in the use of these resources is that they do not impede or influence primary agricultural needs, notably food.

The focus of this white paper is on e-SAF and hence the utilisation of non-biogenic carbon. Prof. MacElroy looks into eFuel pathways for sustainable aviation, with an emphasis on how captured CO₂ and green hydrogen can be used to produce low-carbon aviation fuel and he looks at the science behind these routes, their benefits, and the barriers to scale-up.

• Sustainable Aviation Fuel and eSAF
• Direct Air Capture as a CO₂ source
• Pathways:
  – Indirect RWGS-FTS
  – Direct CO₂-FTS
  – Indirect CO₂-Methanol Mediated Route
  – Direct CO₂ (Methanol Mediated) Route
• Benefits and limits of each route
• Scale-up, cost and commercial readiness

 

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For more:

• What is eFuel?
• What is eMethanol?
• Sustainable Aviation Fuel (SAF)
• Methanol-to-Jet Fuel for Sustainable Aviation
• Lift Off for NEG8 Carbon in Sustainable Aviation Fuel
• CORSIA vs EU ETS

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