Planes can’t easily run on batteries, so airlines are betting heavily on new kinds of fuel to cut their emissions. Here’s what sustainable aviation fuel is, and why there isn’t much of it yet.
Aviation produces around 2 to 3% of global carbon dioxide emissions, and that share is expected to grow as more people fly and other industries cut their emissions.
It’s one of the hardest industries to decarbonise. Batteries are far too heavy for long flights, and hydrogen-powered planes are still many years away.
What it is
Sustainable aviation fuel, or SAF, is jet fuel made from renewable or waste sources instead of fossil fuels.
It can be made from used cooking oil and animal fats, agricultural and forestry waste, crops such as canola and sugarcane, and eventually from green hydrogen combined with carbon dioxide captured from the air.
When it burns, it releases similar amounts of carbon dioxide as regular jet fuel. But because the carbon came from plants or waste that absorbed carbon dioxide, rather than from fossil fuels, the overall emissions across its lifecycle can be much lower, up to around 80% lower depending on how it’s made.
It can be blended with normal jet fuel and used in existing planes and airport fuel systems, which makes it one of the most practical ways to cut aviation emissions now.
The problem
SAF makes up a tiny share of jet fuel used worldwide, well under 1%. It typically costs two to five times as much as regular jet fuel, and supply is limited. Fuel is already one of an airline’s biggest costs.
There are also concerns about whether there’s enough sustainable feedstock to make it in large quantities without competing with food production.
Australia’s plans
Australia has many of the raw materials needed to produce SAF, but currently imports most of its jet fuel and produces almost no SAF.
The Federal Government has announced a $1.1 billion Cleaner Fuels Program to support local production of low-carbon liquid fuels, including SAF, and has consulted on other incentives.
Qantas has set targets to use 10% SAF by 2030, and has invested in local production projects. Virgin Australia also has SAF plans.
Other ways to cut emissions
Airlines are also cutting emissions by buying newer, more fuel-efficient planes, which typically burn 15 to 25% less fuel than those they replace, and by improving operations, such as more direct flight paths.
Many airlines offer passengers the option to pay to offset their flight’s emissions. Critics say offsets can be unreliable, and that the only way to reduce aviation emissions significantly in the short term is to fly less.
Most of the world’s major airlines have committed to reaching net zero emissions by 2050, but have acknowledged it will depend on huge growth in SAF and new technology.
