Op-Ed

Turning Waste into Wings: The Future of Sustainable Aviation

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The aviation industry is currently at a pivotal point in its sustainability journey. With increasing global pressure to reduce carbon emissions, the need to develop and scale up sustainable aviation fuel (SAF) production has become more urgent. SAF, a fully certified jet fuel that can be used in today’s aircraft engines and transported via existing infrastructure, has the potential to be a significant decarbonization tool for aviation. Its compatibility with the current state of the aviation industry underscores its importance. However, the success of SAF depends not only on its usage but also on the methods used in its production.  

ASTM International (formerly the American Society for Testing and Materials), the leading global organization setting technical standards across various industries, including aviation fuel, plays a crucial role in ensuring the credibility and reliability of the approved production methods for SAF. Their approval of several production methods, typically referred to as pathways, for producing SAF provides a solid foundation for the industry's sustainability efforts. 

SAF pathways start with a specific renewable raw material—such as used cooking oil, municipal solid waste or ethanol—and then convert that raw material to jet fuel through a series of chemical reactions frequently using heat, water, or hydrogen. 

SAF is Taking Off

The demand for SAF is expected to rise significantly, with projections forecasting a tenfold increase over the existing supply to more than 7 billion gallons per year by 2030. Even with this large increase, SAF will only account for about 5% of global jet fuel demand, which means we have further to go to reach industry goals. In the United States, the White House has set an ambitious goal of achieving 100% SAF use in U.S. aviation by 2050. 

With the increasing use of SAF by airlines, the urgency of scaling up production has become more pronounced. This is crucial to meeting both short-term and long-term goals. However, the current dominant production pathway, HEFA (i.e., Hydroprocessed Esters and Fatty Acids), which accounts for about 95% of the market due to its relatively low deployment costs, is encountering feed availability issues that are only expected to worsen. The competition among HEFA processors to gather enough vegetable oil, animal fat, and used cooking oil to meet demand is a clear indication of the urgency of the situation and the need to diversify SAF pathways to ensure sustainable growth. 

As the availability of these feedstocks becomes increasingly scarce, the cost-effectiveness of HEFA as a SAF pathway diminishes. Even today, HEFA exceeds the cost of conventional jet fuel by 2 to 4 times.

Fuel producers are actively exploring alternative pathways with more abundant feedstocks to meet the growing demand for SAF. The Fischer-Tropsch (FT) pathways, in particular, hold significant promise. With the potential to use municipal solid waste and agricultural and forest waste as primary feedstocks, FT pathways offer a hopeful solution to produce a substantial portion of the SAF target. This upgrading from a waste to a valuable resource could have a profound positive impact on both the environment and the aviation industry. 

Turning Waste into Wings

FT plants oriented at gasified waste as a feed will be designed small scale to match the feedstock availability of their specific locations. To remain economically viable, these plants must optimize resource use and maximize output. This is not just a goal but a crucial necessity.

While FT processing is capable of producing SAF, it also generates lower-value byproducts such as renewable naphtha and liquefied petroleum gas (LPG), which can account for up to 20% of the output. A challenge for FT plants is getting value out of these byproducts to improve the overall economic return of the plant. While renewable naphtha and LPG can be mixed with fossil fuels to reduce carbon intensity or used as feedstocks for chemicals and plastics, their economic value does not match that of SAF. Additionally, FT plants that process gasified waste are often located far from potential buyers of naphtha or LPG, further complicating their monetization. 

Another potentially challenging variable for FT and HEFA SAF processors is that these pathways only produce paraffinic SAF. Conventional jet fuel contains both paraffinic and aromatic molecules. The aromatics are ring-shaped molecules necessary for the fuel’s physical and combustion properties. ASTM standards require that finished jet fuels contain between 8% and 25% aromatics. Currently, only a 50% blend of FT SAF with conventional jet fuel is approved by the ASTM, so fossil jet fuel provides the aromatics for these blends. However, the ASTM and the industry are moving toward higher SAF blends—eventually to 100% drop-in, synthetic SAF—where no blending with fossil jet is required. Processors will face a critical challenge in finding a source for the aromatics. This is crucial to ensure that their fuel will not require continued blending with fossil fuels, highlighting a key challenge in the future of SAF production. 

Biofuel engineers are making notable progress in creating solutions for the most significant challenges facing SAF production. For example, Universal Fuel Technologies created a chemical processing technology that complements FT by converting renewable naphtha and LPG into aromatic SAF, which could provide a significant economic boost to FT plants and even make them economically attractive, whereas this was not the case otherwise. With 20% of the plant's output transformed from low-value naphtha and LPG to high-value aromatic SAF, the addition of this technology increases the plant’s revenue by anywhere from 10-20%. Including this complementary technology would make the FT plant a better investment, produce SAF that is more cost-competitive with conventional fuels, and enable a fully synthetic 100% drop-in-ready product that can be sold directly to airlines without the need for blending once ASTM-approved. 

The Pathway Forward

SAF is vital for the aviation industry's efforts to cut carbon emissions. It offers a scalable solution that integrates seamlessly with existing infrastructure. SAF could also potentially tackle waste management issues and support a circular economy by converting biomass into valuable fuel.

Significant investments in SAF technologies and infrastructure will be required to achieve the International Air Transport Association’s (IATA) net-zero emissions by 2050 goal. However, with future aviation fuel demand expected to exceed 2 million barrels per day, it is increasingly unlikely that HEFA alone can meet these needs. As the industry looks to meet growing demand and sustainability goals, Fischer-Tropsch pathways could play a pivotal role in shaping the future of sustainable aviation fuel.

While challenges remain, including high initial capital investments and complex integration with existing waste management systems, the potential benefits of FT processing are substantial.  By optimizing the utilization of FT byproducts and leveraging solid waste effectively, this pathway offers a promising solution to both environmental and economic challenges. It could potentially lead to significant reductions in carbon emissions and propel the aviation industry toward a more sustainable future. 


Co-Authors:

Alexei Beltyukov is an accomplished entrepreneur with 25 years of industry experience in energy and transportation. In 2022, he co-founded Universal Fuel Technologies together with Stephen Sims and Denis Pchelintsev. This venture followed their successful collaboration on New Gas Technologies during the preceding decade, marking a strategic pivot towards sustainable fuel technologies. 

Stephen Sims is the Vice President of Business Development for Universal Fuel Technologies, a company he co-founded in 2022 with partners in New Gas Technologies. Stephen has extensive experience in the oil and gas industry, having worked at multiple major oil companies throughout his career. He has also served as a volunteer Energy Advisor with Global Energy Mentors since 2015. 

Environment + Energy Leader