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  • Writer's pictureAndreas Hardeman

It’s Jet Fuel, But Not As We Know It

(Originally published on 13 September 2019)

A few years ago something extraordinary happened. In a brief moment of rare cosmic alignment, environmentalists found themselves siding with their arch-nemesis, Big Oil. Together - although clearly for different reasons - they started arguing against the use of biofuels in aviation. Since then, many oil majors have decided to come on board with the idea, while much of the green lobby persists in its bolshie opposition. So at least in that sense, natural order has been restored.

Biofuels currently account for less than 0.1% of aviation’s total fuel use. This, however, belies the fact that enormous progress has been made in this area in a relatively short time.

Multiple processes (“pathways”) to produce aviation biofuel have been approved by the international standards body ASTM, including Fischer-Tropsch (FT), Hydrotreated Esters and Fatty Acids (HEFA), Synthesized Iso-paraffins (SIP) and Alcohol to Jet (ATJ). And many more are already in the pipeline.

The range of raw materials (“feedstocks”) from which biojet fuels can be derived also keeps growing. Due to their abundance and relative cost advantage, municipal waste and agro-forestry residues are the preferred feedstocks right now for leading suppliers as Fulcrum, LanzaTech, SkyNRG and Neste. Other bio-feedstocks that may produce viable jet fuel replacements one day include non-food oil crops such as jatropha and camelina, modified sugarcane and renewable hydrocarbons, like farnesene.

But there is much more to come. Significant advances in molecular genetics and genomic technologies now enable us to predict and safely manipulate the biological function of biomass feedstocks.

Scientists working with ExxonMobil, for example, have been tweaking the algae genome responsible for nitrogen assimilation, resulting in a strain capable of holding double the fat content of conventional algae and boosting potential yields. Similarly, research is advancing to successfully increase the production of the storage molecule triacylglycerol (TAG) in microalgae. These are advances that will ultimately can make biojet production more efficient and cost-effective.

Recent attempts by biotech companies to genetically engineer microbes, including E.coli, to make hydrocarbon fuels and commercialize cyanobacteria-derived oils only failed because of an untimely slump in crude oil prices.

Within the span of a mere decade, industry has moved beyond simple food crops (soy, corn) as feedstock for biojet fuel (aka 1st generation (1G)) to developing biofuels from genetically optimized non-food feedstocks coupled with carbon capture and storage technologies (aka 4th generation (4G)). Looking at 5G and beyond, we may even see synthetic, carbon-neutral fuels produced from solar energy, CO2 and water via Power-to-Liquid processes as an alternative fuel source for aviation.

In combination with other newly emerging air transport technologies, these developments have the potential to put aviation firmly on a path towards a truly sustainable future.


This is Part 5 in a mini-series of blog posts focusing on emerging air transportation technologies and their contribution to sustainable development.

About the author: Andreas Hardeman (The Hague, 1967) is an internationally experienced air transportation lawyer, sustainability expert and acclaimed aviation writer and commentator on current industry trends. Opinions in this blog are exclusively those of the author and do not necessarily reflect those of his business associates or clients. He can be contacted directly at

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