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Biofuels for aviation
Dean Hislop is managing director of sustainable jet fuel producer Renovare Fuels

Biofuels for aviation

Dean Hislop explains how biofuels are fostering change in aviation

Aviation is an industry of very fine margins. High fuel costs, combined with extremely high operating and capital costs, make it difficult to introduce change into the sector. 

However, recent breakthroughs in biofuels could hold the answer.

There is no doubt that aircraft are beautiful machines. However, this beauty comes at a cost. 

Not only are they expensive to manufacture and buy, aeroplanes are also expensive to keep and maintain. 

What’s more, every element of their upkeep and repair is regulated down to the very fluid that’s used to clean them, which must be approved for use so that it doesn’t cause etching or corrosion on different metal and rubber surfaces.

With so much at stake and such tight regulations to navigate, decisions to change suppliers or components are not taken lightly. It can be difficult, then, to strike a balance between introducing new parts and suppliers that will deliver better efficiencies, while managing the stringent regulatory process.

One area that’s placing pressure on aviation procurement teams is emissions targets.

According to the EU Commission, “By 2020, global international aviation emissions are projected to be around 70% higher than in 2005 and the International Civil Aviation Organization (ICAO) forecasts that by 2050 they could grow by a further 300–700%”.

While an emissions trading scheme has been used by the EU to offset emissions, more needs to be done to move towards alternative aviation fuels. 

In March 2018, the ICAO Council endorsed it’s earlier declaration, explaining that “the introduction of sustainable aviation fuels (SAF) is one of the measures that can contribute significantly to ICAO’s climate objectives… and address environmental challenges facing aviation, and may also realise economic, social, and environmental advantages … set out in 13 out of 17 of the United Nations Sustainable Development Goals”.

While biofuels offer a renewable alternative to traditional fuels, there are two main reasons why they have struggled to make commercial headway in recent years. The first problem is capacity and the second is stringent regulation. 

In terms of capacity, the issue is that there are currently no biofuel suppliers that can produce enough fuel at the volumes required to replace traditional fuel. 

The second reason is that stringent regulations currently act as a barrier to the adoption of biofuels.

Under the revised ASTM aviation fuel standards, bioderived fuels can only be blended with, rather than entirely replace, conventional jet fuels.

The two main types of conventional jet fuel currently used across the aviation industry include Jet A and Jet A-1. Jet A is mainly used in the United States and must have a freeze point of minus 40˚C, whereas Jet A-1, which is used in the rest of the world, has a freeze point of minus 47˚C.

What’s more, conventional jet fuel meets the exacting requirements for chemical composition, volatility, fluidity, combustion, corrosion, thermal stability, contaminants and additives. 

Any biofuels that want to compete need to be nearly chemically identical to these existing fuels. This is made difficult because certain types of naturally occurring hydrocarbon aromatics present in conventional fuels cannot be synthesised in most biofuels.

After many years of development, Renovare Fuels has developed a way of converting waste biomass into high-grade hydrocarbon biofuel. This process of converting raw biogas uses a Fischer-Tropsch synthesis catalyst to produce a fuel that, when blended, is around 90% identical to aviation fuel, while being completely carbon neutral. 

It also has an approved fuel certification pathway as an aviation fuel under ASTM standard D7566, and with further development could well offer a “drop-in” replacement for conventional jet fuel.

While there is no doubt that aircraft are beautiful machines, what’s even more awe-inspiring is not just how far we’ve come on the journey to biofuels, but how soon this could become a commercial reality.

Dean Hislop is managing director of sustainable jet fuel producer Renovare Fuels.

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