The global aviation industry is responsible for 12% of global carbon dioxide (CO2) emissions from transport. Conventional aviation fuel is derived from either oil, coal, or gas, all of which are major culprits of global warming. To honour their sustainability commitments, an increasing number of airlines are transitioning to Sustainable Aviation Fuel (SAF) to reduce their carbon footprint. Accelerating the uptake of SAF requires a combination of structural upgrades as well as supportive fiscal and policy measures.
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Considering the hundreds of thousands of planes that take the sky each day, it might be surprising to many that the global aviation industry is responsible for “only” 12% of the total CO2 emissions generated by the transport sector. However, the aviation industry is projected to experience significant growth, with experts estimating annual passengers to rise to 6.9 billion by 2035.
As more people migrate to cities for economic opportunities, the demand for air travel will only increase. Recognising this, the aviation sector has already committed to halving CO2 emission levels by 2050 relative to 2005 levels, during a pledge made in 2019.
At COP26 in Glasgow, the aviation industry also pledged to “advance ambitious actions to reduce aviation CO2 emissions at a rate consistent with efforts to limit temperature increase to 1.5°C.” Developing and scaling Sustainable Aviation Fuel (SAF) is a key step that can help the aviation sector to reduce their emissions.
What Is Sustainable Aviation Fuel?
Sustainable Aviation Fuel (SAF) is an alternative fuel source derived from a variety of feedstocks, and it differs from traditional jet fuel because it does not use sources such as oil, coal or gas. SAF feedstock sources range from cooking oils and municipal waste to food scraps and energy crops.
The aviation industry specifically chose to use the phrase “sustainable” aviation fuel to highlight its commitment to sourcing feedstock sustainably as there have been instances where the cultivation of feedstock for biofuel has adversely affected the environment. For example, deforestation and land use change have occurred in certain areas to create more land to cultivate energy crops for biofuel production.
Secondly, the term “biofuel” is not used because there are some types of SAF that may be derived from non-biological sources. For instance, SAF can be derived from the “power to liquid” process; this process aims to recover the byproducts of manufacturing and turn them into fuel. One example is turning waste gases from steel manufacturing into an input for SAF.
According to the International Civil Aviation Organization (ICAO), “alternative fuels” is defined as “any fuel that has the potential to generate lower carbon emissions than conventional kerosene on a life cycle basis.” ICAO also uses the term “sustainable aviation fuel.”
What Are the Benefits of SAF?
SAF has the potential to reduce up to 80% of lifecycle emissions – which accounts for the emissions made during the entire production of SAF – compared to traditional fossil fuels. What’s more, depending on the feedstock, using SAF can provide further environmental and economic benefits. Using municipal waste as feedstock is an example of circular economy principles in practice. By deriving SAF from waste, it reduces the amount of waste left to decompose in landfills while also reducing the additional CO2 emissions that will be emitted during the decomposition process.
When energy crops such as camelina are used, farmers can also experience added economic benefits. Since camelina is a rotational crop that can rotate with crops such as wheat, it can create a new income source for farmers. This also reduces mono cropping, which is known to affect soil health and lead to increased pest infestations.
Thirdly, using SAF will stabilise the cost of aviation fuel by reducing reliance on fossil fuels. Compared to fossil fuels, which are limited by supply and geographical location, SAF can be derived from multiple sources. As more SAF feedstock suppliers come into the market, the price of SAF is expected to stabilise, offering airlines a more sustainable fuel source less affected by price fluctuations.
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Is SAF Safe to Use in All Aviation Fleets?
All SAF blends must be certified under ASTM D1655, the same standard used for traditional jet fuel. If SAFs are verified under this standard, no further modifications need to be made for it to be adapted aircrafts parts. Currently, SAF can only be used in blended form. Blend ratios vary depending on feedstock, but the maximum allowed blend of SAF is 50%.
Earlier this year however, a team of aerospace specialists launched the world’s first in–flight emissions study using 100% SAF, showing positive advancements in the use of 100% SAF in aircrafts in the future.
What Is the Current Uptake and Usage of SAFs?
The first ever flight to exclusively use SAF took off in 2018. Since then, uptake has been modest when compared to total industry fuel demand. Two of the key reasons for the modest uptake are the limited supply of and accessibility to SAFs. SAF is only produced in small quantities due to limited feedstock and facilities, meaning its unit cost of production is higher than traditional fuels. The overall higher price of SAF is a significant barrier to more widespread usage across airlines.
Secondly, many airports do not have the mechanisms in place to provide SAF to aircrafts. As of September 2017, only four global airports, including Oslo, Bergen, Stockholm and Los Angeles, can provide a consistent SAF supply.
According to IATA (International Air Transport Association), the world consumes 278 billion litres of fuel for aviation. Based on their analysis, there can be a viable market for SAF even if as little as 1% of the world’s fuel uses SAF, i.e if 10% of the world’s aircrafts runs on a fuel that is a 10% SAF and 90% traditional fuel blend.
How Can We Accelerate SAF Usage Across Aircrafts?
Acceleration of SAF usage across global aircrafts requires both infrastructure development and policies that can support its uptake.
Policy initiatives that can propel SAF usage include allocating sufficient feedstock for fuel production and financing processes to scale SAF production. A report about the availability of feedstock SAF production concluded that because feedstock is mainly diverted for use in other transportation sectors, there will be limited availability for SAF production absent strong policy support and investment.
Other ways policymakers can support SAF adoption include allocating funding into feedstock research and development (R&D), and refining processes, providing incentives for airlines to use SAF and de–risking private and public investments in SAF.
Investments in the infrastructure needed to make it more accessible are just as important. In July 2021, the European Union proposed a new regulation called ReFuel EU, aimed at levelling the playing field for SAF across EU countries. As part of the regulation, EU airports are required to provide the necessary infrastructure for the supply and blending of SAF. However, due to the global nature of flights, it is important for airports around the world to offer similar infrastructure in order for SAF to be commercially viable.
Although the widespread adoption of SAF will help the aviation industry reduce emissions, advancements in aircraft design and operational efficiency are also key to reduce emissions. Aircrafts such as the Boeing 787 are already 80% more fuel efficient than aircrafts in the 1950s, reflecting the positive environmental advancements that have already occurred in the aviation industry.
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