Sustainable Aviation Fuels: 5 Key Challenge Areas

Aviation is one of the most difficult sectors to decarbonise. The industry is responsible for 2–3% of global greenhouse gas (GHG) emissions, a share that is only expected to keep rising.

 

Despite ambitious targets to achieve net-zero carbon emissions by 2050, the industry has faced significant challenges in reaching them. Finding sustainable alternatives to conventional jet fuels has proven difficult, with most failing to meet the demanding performance needs. Every kilogram of weight and every cubic meter of space directly impacts range, payload, and efficiency, making it complex to produce.

 

Sustainable Aviation Fuel (SAF) emerges as the primary near-term solution since it offers a similar energy density to conventional jet fuel but without the space and weight penalties that batteries or hydrogen bring. SAF could drastically reduce lifecycle greenhouse gas emissions by up to 90%. 

 

This article explores what SAF is and the key challenges we need to overcome for it to reach commercial scale.

 

What is SAF?

 

SAF is an alternative fuel made from non-petroleum feedstocks that reduces emissions from air transportation while maintaining compatibility with existing aircraft infrastructure.

 

The fuel can be manufactured from various sustainable resources, including waste oils, agricultural and forestry residues, municipal solid waste, used cooking oil, and even captured carbon dioxide. These feedstocks are processed through approved production pathways such as Hydroprocessed Esters, Fatty Acids (HEFA), Fischer-Tropsch synthesis, and Alcohol-to-Jet conversion, each certified under strict ASTM standards.

 

Unlike long-term alternatives such as hydrogen or electric aircrafts, SAF is already in use and can be scaled to cut emissions in the near and medium term.

 

SAF Key Challenges

 

While SAF represents aviation’s most promising near-term decarbonization solution, several significant barriers continue to limit its widespread adoption and commercial viability. SAFs today meet less than 0.2% of aviation fuel demand, and even commercially ready pathways like HEFA (Hydroprocessed Esters and Fatty Acids) face barriers to large-scale deployment. 

 

These are the five most persistent challenges hindering progress:

 

• High production costs: SAF currently costs two to three times more than conventional Jet A fuel. This is one of the highest barriers to airline adoption, with passengers risking paying the price through steeper ticket prices.
• Feedstock availability: Sustainable feedstocks are limited and compete with other sectors such as road transport, agriculture, and petrochemicals. This has led to volatile feedstock prices and supply uncertainties, hindering production. 
• Certification requirements: Each new SAF production pathway must be rigorously tested and certified by standard bodies such as ASTM, which creates adoption bottlenecks. The ASTM D7566 standard defines specific requirements for each production pathway and the certification process is often lengthy and expensive.
• Blend limitations: Safety regulations currently mandate blending SAF with conventional kerosene, restricting the proportion of SAF in use as well as the emissions reduction. Current regulations limit SAF blends to between 10% and 50% depending on the production pathway.
• Persistent NOx Emissions: While SAF reduces overall carbon emissions,  it does not fully eliminate nitrogen oxide emissions, which still pose environmental concerns. Non-CO2 effects from aviation, including NOx emissions and contrail formation, account for more than half of aviation’s climate forcing.

 

Learn more about the different innovation pathways or dive into the investment trends.

 

SAF holds only one part of the solution

 

While SAF offers a promising route to lower CO2 emissions, it cannot alone eliminate aviation’s full environmental impact. Improving aircraft efficiency, upgrading operations, and advancing electrification for short-haul flights are all essential to meet aviation’s climate goals, as no single solution can fully decarbonise the sector.

 

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