What is sustainable aviation fuel (SAF)?

Sustainable aviation fuel - which is sometimes referred to as biofuel, renewable aviation fuel, renewable jet fuel, alternative fuel or biojet fuel - is synthesized from a wide range of sustainable feedstocks rather than being made from fossil fuels. Some of the sustainable feedstocks being used to produce SAF are waste oil and fats; municipal solid waste; cellulosic waste (such as corn stalks); and other feedstocks.

Carbon reduction with SAF

Relative to fossil fuels, SAF results in a reduction in carbon dioxide (CO2) emissions across the entire lifecycle of the fuel. This includes the CO2 required to grow or produce the feedstock being used to generate the fuel, and the CO2 required to capture, transport, and refination of the material. Lifecycle analysis shows the fuel provides significant reductions in overall CO2 emissions when compared to fossil fuels. Lifecycle CO2 reductions across the different sources of neat SAF may reach up to 87%* compared to conventional jet fuel over its entire life span, In the future years, enhancements in the production process and the use of other instruments such as carbon capture could see this percentage increase to 100% CO2 reduction. This significant emission reduction will contribute a lot to us for our carbon-neutrality target by 2050.

*when the reduced GHG emissions are calculated by comparing to a GHG baseline intensity of 94gCO2e/MJ, which is the carbon intensity of the Fossil Fuel comparator under the Renewable Energy Directive 2018/2001/EU, life cycle CO2 reductions across different SAF sources can reach up to 87%.

How to use SAF?

The chemical and physical characteristics of SAF are almost identical to those of conventional jet fuel. SAF can be mixed with conventional jet fuel, and once blended, is certified to exactly the same standard as conventional jet fuel. Fuels with these properties are called “drop-in fuels” (i.e. fuels that can be directly incorporated into existing airport fuelling systems and on board aircraft). This allows use of the same supply infrastructure and does not require the adaptation of aircraft or engines.

SAF supply chain

Challenges in the Sustainable Aviation Fuel (SAF) supply chain affect efforts to reduce carbon emissions in aviation. The disruption in the supply of suitable feedstock, which results in high costs and low supplies, is the main factor constricting the utilization of SAF. Feedstocks used in SAF production come from sources such as biomass, waste oil and agricultural waste. As these resources are also deployed in other sectors, obtaining sufficient raw materials for SAF production can be difficult. In 2023, SAF production was just 0.2 per cent of global jet fuel use. While the amount mixed with conventional jet fuel is 0.5 - 3 per cent, a maximum of 50 per cent can be used.