An Airbus powered by cooking oil: Is sustainable aviation fuel the future of aviation?

Used cooking oil is probably not the first thing that springs to mind when you think about your next holiday flight. But that could soon change. Airbus has just completed its first test flight of an A380 jumbo jet with one engine powered entirely by sustainable aviation fuel (SAF). The fuel used was a mix of used cooking oil and other waste fats, purified to extract sulphur and other contaminants.

The aviation industry is widely acknowledged as one of the hardest to decarbonize and its share in global emissions is around 2%.

The industry has already made major investments in electric and hydrogen-powered aircraft. Switching to alternative propulsion and sustainable fuels plays another big part in its efforts to cut CO2 emissions in the race to reach net-zero by 2050. The first test flight with bio jet fuel goes back to 2008. By the end of 2019, more than 200,000 commercial flights had used SAF, mainly blended with kerosene.

Airbus has now added further momentum by flying the largest passenger aircraft in the world for three hours using a mix of kerosene and SAF. One of the outer engines was powered entirely by sustainable aviation fuel during the test. The A380 joins its smaller relatives, the Airbus A350 and the A319neo, which went through similar tests last year.

Sustainable aviation fuel comes in a variety of guises, all of which have in common that they can deliver performance on a par with kerosene jet fuel but with a fraction of the CO2 emissions.

SAF (sustainable aviation fuel) can be made from a wide variety of sources. These include corn grain, algae, agricultural and forestry residues, solid waste and dedicated energy crops. Many SAFs contain fewer aromatic components than kerosene, enabling them to burn cleaner. This improves aircraft performance and also reduces emissions of pollutants other than CO2.

SAF could contribute between 53% and 71% of the sector’s required emission reductions by 2050, according to a 2021 report from the Air Transport Action Group (ATAG).

As with so many sustainable and renewable energy sources, SAF still comes at a high cost: sustainable aviation fuel currently costs around four times as much as conventional jet fuel. As a result, supplies are limited, with production currently estimated at less than 0.1% of global jet fuel consumption. Even the expected increase to about 3% of forecast demand in 2030 will fall short of targets set by legislators such as the European Union in its Green Deal, according to BloombergNEF. More demand would boost production and bring prices down.

Another issue is that not all sustainable aviation fuels are created equal. Some production methods are more CO2-heavy than others, as a working paper from the International Council for Clean Transportation (ICCT) has pointed out. The key will be to make the most of those methods that offer the best greenhouse gas savings, the ICCT concludes.

However, the importance of SAF as a major route towards decarbonizing the aviation sector remains. This was underlined when 60 members of the World Economic Forum’s Clean Skies for Tomorrow Coalition came together in autumn 2021 to commit to achieving broad industry adoption of SAFs by 2030. The aim is to tackle what the signatories call the “chicken and egg” problem around supply and demand of sustainable aviation fuels, supported by both industry and policy initiatives. The coalition is targeting a share of 10% of global jet aviation fuel to be SAF by 2030.