On the ground, we see and hear planes flying overhead with a trail of burnt fuel streaming out behind them. Inside the plane, little thought is often given to what is fueling the ride from here to there. But it should be. The aviation industry has been credited with contributing around 10% of the country’s travel emissions, according to the EPA. Thankfully, industry leaders and fuel producers are looking for cleaner options with a vision for a more environmentally-friendly future for air travel.
What is sustainable aviation fuel?
Sustainable aviation fuel is airplane fuel made from biomass materials. That can be an assortment of things, all of which are renewable or converted from waste products.
Is SAF the same as biofuel?
No. Well, not exactly. SAF is biofuel, but biofuel is not necessarily SAF. Think of it as certified biofuel. Let’s clarify. Biofuel is made from biomaterials (plant and animal materials). However, it’s not measured for sustainability. For example, fuel made from palm oil is biofuel, but few would argue palm oil harvesting is sustainable with the current spotlight on deforestation and habitat destruction. On the other hand, sustainable aviation fuel is created from responsibly-sourced materials that do not contribute to deforestation, compete with food manufacturing, or endanger the environment.
How is SAF made?
There are several primary technologies used for making SAF. There are also myriad ingredient options in the SAF recipe, each with its own list of benefits.
Municipal waste — This is exactly what you think it is. Chicken bones, banana peels, packaging waste, paper, plastic, clothing, furniture and more are converted into jet fuel. It’s easy to see the win-win arrangement here. Not only does the process divert waste from the landfills where it contributes to methane gas release, but it is converted into a useful resource.
Agricultural waste — Sustainable aviation fuel can also be made from agricultural waste, including those from crops and forestry practices.
Oil — You’ve heard of used cooking oil being used for automotive fuel. A similar process can convert it into biofuel, making use of an otherwise waste product.
Crops — There are several types of plants that are prime candidates for conversion into SAF. The key benefit of these crops is that they are grown during the traditional off-season, opposite of field fillers like wheat. Camelina, rich in oil, is a prime example. Others, such as jatropha, can be grown in poor soil areas not used in food production. These options provide an additional income stream for farmers and make use of land that would otherwise sit vacant temporarily or permanently. Halophytes, which grows in saltwater or coastal areas where salty ocean spray doesn’t allow crops to grow, is another biomaterial used for SAF.
How do we implement it?
We already have! You may have already been on a flight with SAF in the fuel tank. The makeup of SAF is so similar to traditional, petroleum-based fuels, it can be mixed in and instantly cut the carbon footprint of flights. There are no engine changes or adjustments required, so it’s easy to implement.
However, SAF can’t yet be used at higher than a 50/50 ratio. Some SAFs can only be 10% of the mix. This is because most older engines rely on ingredients in petro fuel to maintain seals in the engine. The conversion is slow, but newer engines have been adapted to overcome this issue and can efficiently burn 100% SAF.
All combinations of fuels, regardless of the materials and processes used to manufacture them, are put through rigorous testing. These tests measure the performance of the plane from startup to takeoff, as well as deceleration and landing. Emissions are measured and all parts are inspected to ensure safety.
Problems with SAF
Cost is the primary issue. This is mainly due to low production levels. As demand increases for SAF, production will also increase, bringing the price down. That leads to the second primary issue, which is the lack of supply. As the commitment from airlines escalates, new production facilities will be needed. Systems also need to be put into place to provide the feedstock (crops, waste, etc.) that will drive SAF production.
Current needs and uses of SAF
In addition to investments from producers and airlines, the industry relies on governmental support. This comes in many forms, including subsidizing farmers, investments in the technology and regulations that support manufacturing.
Myriad companies have already made commitments in support of SAF production. This summer, Mercedes announced its investment in SAF in conjunction with its goals to become net zero by 2030. That’s no easy feat with a traveling race team that racks up airline miles. But it shows Mercedes’ commitment to go beyond the goals of Formula 1 to achieve net zero by 2030, at least on the racetrack, through the use of sustainable fuels. Mercedes is carrying the idea over to business travel to and from racing events, too.
American Airlines is also stepping up with the largest commitment in its history, vowing to purchase 500 million gallons of SAF from biofuel provider Gevo over the next five years.
Is sustainable aviation fuel here to stay?
Only the future knows the answer to that question, but it’s certainly promising in the short term if nothing else. With the heavy lean into the benefits of waste conversion, reduction in air pollution and economic support to several industries, this won’t be the last we hear of SAF.
Images via Pixabay