A Soaring Guide to Sustainable Aviation Fuels

Firstly, what is an aviation biofuel? Quite simply, it is a biofuel that can be used as a replacement for traditional aviation fuels. Although, they have to meet existing aviation fuel specifications, so existing systems and engines can use them. The term drop-in biofuel is also used.

But why use biofuel for aviation?

Many governments around the world have made a commitment to reduce greenhouse gas emissions (GHG) by 2050. To achieve the reductions needed all industry sectors, as well as households, must play their part.

It is estimated that by 2050, 3-5% of global GHGs will be from aviation emissions. A recent report into the UK aviation industry estimated that by using biofuels in the fuel mix, there could be a saving in aviation carbon emissions of up to 18% by 2050.

Building more efficient engines, operating aircraft more efficiently and using a different fuel is aviation’s options for reducing its carbon footprint. Although research into alternative fuels like hydrogen and solar power is taking place, these are unlikely to be useful in the medium term. So at present, using sustainable biofuels represents the best option for making the aviation industry greener.

Pathways to biofuel

There are currently three pathways used to manufacture drop-in biofuels that meet US and European regulations. The biofuels produced from these pathways can be used in blends with kerosene - the traditional aviation fuel. The fuels use waste materials from other production pathways as the raw materials for their manufacture.

The three pathways are:

Fischer Tropsch (FT)

• Converts solid biomass into synthetic gas and then further into fuel.
• Known as Biomass-to-Liquid (BtL) fuel.
• Can be blended with a maximum of 50% with kerosene.

Hydrotreated Esters and Fatty Acids (HEFA)

• Converts oils into fuels, similar to the existing crude refining process.
• Research into algal oils as a replacement for plant oils is ongoing.
• Can be blended at up to 50% with kerosene.

Renewable Synthesized Iso-Paraffinic (SIP)

• Produced from fermented sugars.
• Sugarcane is converted into farnesane hydrocarbon.
• Can be blended up to 10% with kerosene.

Timeline for aviation biofuels

Take a look at the history of aviation biofuels:

• February 1998 - First flight using biofuel, a 20% mix with kerosene in one engine.
• June 2011 - First commercial flight with biofuel, Amsterdam to Paris.
• October 2012 - First flight using 100% biofuel.
• October 2013 - Commercial flight using SIP fuel in Brazil: Brazil sees first flight on biofuel

But what is the future for aviation biofuels?

One of the problems of biofuels at present, and not just aviation biofuels, is to find alternative feedstock. Any future developments in biofuels must use precursors that do not compete with foodstuffs for land.

Ultimately, the hope is that as the market for these fuels increases, and the development of biofuels in general, that aviation fuels will be able to be produced alongside other biofuels. This will reduce costs and generate investment to allow for the development of faster and better pathways.

Commercial jet fuel is a high-quality fuel, but if it fails to meet this required purity and other quality tests for use on jet aircraft, it is commonly sold to other ground-based users with less demanding requirements, meaning a loss of profit. With over $50 Billion spent on Aviation fuel per year, lab and process chemists are faced with a variety of challenges in their quality control process. For two of those specific analytical challenges new solutions based on gas chromatography (GC) are presented. This article, Solutions in Aviation Fuel Analyses Using Gas Chromatography, looks at this topic in more detail.