One of the most exciting developments for aviation is the use of sustainable biofuels to replace the standard kerosene, or Jet-A, fuel that is currently being used. It is clear that our industry’s dependence on fossil fuels is not sustainable, and we see that with innovation, future generations of biofuels for aviation can and will be developed in a sustainable manner. Rapidly developing research shows that next-generation biofuels can be a viable energy source for aviation, and the industry expects that further investigation will develop fuels that can be mass-produced at a low cost and high yield with minimal negative environmental impacts. Importantly, the aviation industry is committed to exploring the use of biofuels that in no way compete for land or water with food supplies, which has been an issue in other sectors.

The term ‘biofuels’ refers to a wide-range of fuels made from almost any form of recently living organic matter, as opposed to fossil fuels made of organic matter from millions of years ago. Biofuels can be categorised by type, such as bioethanol, biodiesel and biogas; and by source, such as sugarcane, maize, wheat, rapeseed, agricultural waste products and algae.

Aviation requires a high-performance fuel that operates in a broad range of conditions and does not compromise safety. Furthermore, next-generation biofuels must be a direct replacement for traditional kerosene fuel (Jet-A) so that manufacturers do not have to redesign the engines and so that airlines and airports do not have to develop new fuel delivery systems, which would delay the introduction of biofuels. Currently, the industry is focused on producing biofuels from sustainable sources that will enable the fuel to be ‘dropped in’ to Jet-A1 – in other words, blending biofuel with fossil fuel until enough biofuel can be produced to fully supply the industry.

Sustainability is the key word for biofuels. In fact, some biofuels have a worse environmental performance than the fossil fuels that they are meant to replace. This is why it is important to use the most advanced biofuel production technology and the best biofuel feedstocks. Many of the ‘first generation’ fuel sources, such as ethanol (produced mainly from corn or sugarcane), have been suggested to cause food shortages in developing nations, taking valuable land and wasting water supplies. Many ‘first generation’ biofuels simply will not work in aircraft, such as ethanol. While 13 trillion gallons of ethanol are being used to power automobiles every year, it would freeze at the high altitudes at which a plane flies, making it non-usable for aviation purposes. Any biofuel used in aircraft would also have to be able to operate at high temperatures, have a low freeze point and be cost-competitive with petroleum-based jet fuel.

It is important to use the most advanced biofuel production technology and the best biofuel feedstocks (images courtesy of Boeing)

The second-generation biofuels currently under advanced development for aviation – such as algae and jatropha – are fast growing, non-food crops that don’t take up land that would be used for food production. In fact, both of these potential feed stocks can be cultivated in some fairly inhospitable places, with much lower requirements for fresh water.

Relative to fossil fuels, sustainably produced biofuels result in a reduction in carbon emissions across their lifecycle. Carbon dioxide absorbed by plants during the growth of the biomass is roughly equivalent to the amount of carbon produced when the fuel is burned in a combustion engine – which is simply returning the CO2 to the atmosphere. Biofuels are anticipated to provide an 80% reduction in overall CO2 lifecycle emissions compared to fossil fuels.

Carbon lifecycle diagrams
Fossil fuels Biofuels
At each stage in the distribution chain, carbon dioxide is emitted through energy use by extraction, transport, etc
Carbon dioxide will be reabsorbed as the next generation of biofuel feedstock is grow

Second-generation biofuels must have the ability to directly substitute traditional jet fuel for aviation (known as Jet A and Jet A-1) and have the same qualities and characteristics. This is important to ensure that manufacturers do not have to redesign engines or aircraft and that airlines and airports do not have to develop new fuel delivery systems.

At present, the industry is focused on producing biofuels from sustainable sources that will enable the fuel to be a “drop-in” replacement to traditional jet fuel. Drop-in fuels are combined with the petroleum-based fuel either as a blend or as a 100% replacement.

Some first-generation biofuels, such as biodiesel and ethanol, are not suitable fuels for powering commercial aircraft. Many of these fuels don’t meet the high performance or safety specifications for jet fuel.

Recent advances in fuel production technology have resulted in jet fuel produced from bio-derived sources that not only meets but exceeds many of the current specifications for jet fuel.

Now that biofuels for aviation are a confirmed viable option and the certification process is underway, one of the biggest challenges is cultivating the required quantity of feedstocks. The worldwide aviation industry consumes some 1.5 to 1.7 billion barrels of Jet A-1 annually (about 250 billion litres, or 70 billion gallons). Analysis suggests that a viable market for biofuels can be maintained when as little as 1% of world jet fuel supply is substituted by a biofuel

The aviation industry is committed to sustainable biofuels use in commercial flights to become a reality in three to five years and a significant supply of biofuel in the jet fuel mix should be a reality before 2020. It is now up to dedicated stakeholders across the aviation sector, with help from governments, biomass and fuel suppliers to ensure that the low-carbon, biofuelled future for flight becomes a reality.

There are many experiments and trials in progress. This section looks at those tests and reports on their outputs.

Carrier Aircraft Partners Date Biofuel Blend
B747-400 Boeing,
GE Aviation
23 Feb 08 Coconut & Babassu 20% one engine

B747-400 Boeing,
30 Dec 08 Jatropha 50% one engine

B737-800 Boeing,
GE Aviation,
7 Jan 09 Algae with Jatropha 50% one engine

B747-300 Boeing,
30 Jan 09 Camelina, Jatropha and Algae blend 50% one engine

A320-200 Airbus,
By spring 2010 Sustainable feedstocks TBA


A320 CFM,
Early 2010 Salicornia (Halophyte) TBA

TBA TBA October 2009 TBA TBA

Air New Zealand flight on Jatropha, 30 December 2008

This test flight was performed in Auckland, New Zealand on a Boeing 747-400 with one engine running on a 50% mix of biofuel.

For more information on this biofuel test flight, check out the Air New Zealand flight web page.

Continental Airlines flight on Algae and Jatropha, 7 January 2009

This test flight performed better than expected, with the fuel having the same performance as normal jet fuel, but the pilots reporting that less of the fuel was used, meaning it is potentially more powerful than normal jet fuel.

Latest information: Japan Airlines flight on Camelina, Jatropha and Algae, 30 January 2009

This test flight went as well as expected, according to the pilots, with the biofuel mix in engine #3 behaving in exactly the same way as the pure jet fuel in the other three engines.

Find out more about the efficiencies gained by improving operations »

With the current explosion of interest in sustainable aviation biofuels, the Geneva-based Air Transport Action Group has developed a Beginner’s Guide to Aviation Biofuels, looking at the opportunities and challenges as the industry moves towards this new source of fuel.

• Download The Beginner’s Guide to Aviation Biofuels
• Download the reference version of The Beginner’s Guide to Aviation Biofuels
• Download the key points card

The Beginner’s Guide to Aviation Biofuels was produced with the assistance of: Airbus, Airports Council International, Boeing, Bombardier, CFM International, Civil Air Navigation Services Organisation, GE Aviation, Honeywell, International Air Transport Association, Pratt & Whitney and Rolls-Royce.

Sourced and published by Henry Sapiecha 19th July 2009


Leave a Reply