A growing number of companies are also making bulk purchases of SAF from producers, airlines and corporate travel agencies as they look to reduce carbon emissions to meet environmental targets and encourage mass production of cleaner fuels.
What Is SAF?
It is a liquid fuel that can be blended with conventional jet fuel without the need to develop new planes or engines. It can reduce carbon emissions by up to 80%, though at present it costs around three to five times as much as conventional fuel.
The emissions are saved throughout the production process because the feedstocks used to make SAF have lower lifecycle emissions than conventional jet fuel.
SAF accounted for only 0.5% of aviation fuel in 2021, but many airlines have a target of 10% by 2030 and the industry's goal of "net zero" emissions by 2050 relies on SAF accounting for 65% of fuel.
How Is It Produced?
It can be produced from a number of sources including oils and fats, green and municipal waste and non-food crops.
The dominant feedstock at present is vegetable oil, including waste oil from cooking and virgin oil.
KPMG, however, said in a report last month that the availability of vegetable oil feedstock will be limited by overall supply as well as rival uses in road and maritime fuels that are less complex to produce and offer easier profit potential.
How "Green" Is SAF?
Some SAF feedstocks like palm oil have raised sustainability concerns because of the risk of land use change and the difficulty of tracing the feedstock origins, according to the World Economic Forum (WEF).
European non-governmental organisation Transport & Environment has also warned over the use of some animal fats that can be used for food and feed and to make soaps and cosmetics. If those fats are used in SAF, palm oil is the cheapest alternative and most likely substitute.
What Are Future Options
The growing amount of SAF required to meet environmental targets has companies looking for new and more sustainable feedstocks.
Options being researched include power-to-liquids that would convert renewable electricity, hydrogen and carbon into synthetic fuels, which KPMG said has the strongest potential for large-scale SAF production in the longer term.