Feedstocks – a catalyst for the future of Aviation

In 2050, the aviation industry fuel landscape will likely look very different from today. In fact, in support of the industry’s goal to attain net-zero greenhouse gas (GHG) emissions by 20501, much effort is being placed on developing and certifying pathways to produce Sustainable Aviation Fuel (SAF). Today, ExxonMobil is growing lower GHG emission fuel offerings by leveraging current technology and infrastructure, while continuing research in advanced biofuels that could provide longer-term solutions as society’s needs evolve.

SAF will play a vital role as the industry transitions to less carbon intensive solutions, but today, only a fraction of the SAF supply needed is in production. In the coming decades exponential growth will be required to meet the industry’s goal. Commercialization of feedstocks is a critical catalyst in the evolution of SAF.

Laying the Foundation

Feedstocks are the building blocks of SAF. SAF can be made from feedstocks including renewable or waste materials through various technology pathways. 

So, what are the key factors to consider as the aviation industry moves forward?

  • What feedstocks are available today? Which will require longer range investment, financial support, and technology development to achieve the scale and reliability needed to help reduce CO2 emissions?
  • Which pathways can help the aviation industry make progress towards its net-zero GHG emissions goal?

While SAF feedstocks are in high demand, the supply chains for these feedstocks vary greatly. Some exist today, while others are emerging and must be built from the ground up to attain global scale. Transitioning the aviation industry will require a variety of feedstocks. They will range from sustainably sourced and commercially available feedstocks, such as waste and crop-based oils, to all new feedstock industries, including solid waste conversion and synthetic fuels. The long-range vision for sustainable aviation fuels seeks to maximize the recovery of actual societal wastes, such as waste cooking oils from food preparation, municipal solid waste (MSW), forestry and agricultural residues (solid biomass), and CO2 removed from existing emissions sources or recovered directly from the atmosphere. Careful consideration should be given to competing uses for the same feedstock. For example, pelletized forestry waste may be directly targeted for use for both renewable electricity generation directly into existing power generation facilities and converted to liquid transportation fuels such as SAF. Optimizing the use of scarce feedstocks to maximize GHG emissions reduction will be critical and one of the greatest challenges to meeting SAF demand in the coming decades.

A Natural Synergy

Hydroprocessed Esters and Fatty Acids or HEFA, the conversion of fats, oils, and greases to biofuels, is a proven technology pathway that can leverage installed industrial scale refining and logistics capacity, feedstock supply chains, and technology to launch and rapidly grow SAF supply. HEFA feedstocks include crop-based oil seeds, such as canola/rapeseed and soybean oil, and wastes, such as used cooking oil, waste greases, and animal fats. HEFA can also process emerging cover crops, such as camelina and carinata, grown between viable food-crop seasons. With a carbon intensity reduction potential of more than 70%2, HEFA-based fuel is projected to comprise a significant portion of the global lower carbon fuel supply in the mid-term with rapidly deployable technology to deliver GHG emissions reductions compared to conventional aviation fuel.

HEFA represents a relatively low investment cost pathway that can leverage existing refining capacity to produce renewable diesel and SAF alongside existing liquid fuels. Considering that today most renewable fuels require blending with crude oil-derived fuels, this pathway is the fastest and most investment-efficient means to scale-up SAF now. As the energy transition shifts to increasing volumes of renewable fuels, a natural synergy exists to leverage this existing infrastructure to support the fastest reduction in GHG emissions with the lowest cost burden.

Pathways On the Horizon

The “next generation” pathways, including synthetic fuels PtL (Power-to-Liquid), ATJ (Alcohol-to-Jet) and Biomass Gasification, are high on the desirability scale. These pathways offer the potential to supply lower carbon-intensity fuels that can be scaled to meet energy demands with industrial quantities of available feedstocks that do not compete with food or other non-energy industries. Today, the feedstock supply chains and the process technology to refine these feedstocks into lower GHG emission fuels are in their early stages.  Growing these nascent fuels into cost-efficient global scale production will likely require large capital investments over the coming decades from producers and long-term customer commitments to make them financially viable. 

The Need for Policy

In order to successfully realize society’s ambitions for GHG emissions reductions, well-designed policy is required.  Policy that is technology-neutral, market-based and science-based can enable energy solutions delivering the greatest GHG emissions reductions at the lowest cost. Technology neutrality allows all feedstock and technology solutions the opportunity to contribute to GHG emissions reduction.  Market-based approaches preserve consumer choice and foster competition that drives adoption of the best solutions.  Science-based policy that evaluates emissions on a lifecycle basis using the best available data allows for informed understanding and selection of GHG emissions reduction measures.  Policy that contains these attributes, such as a well-designed Low Carbon Fuel Standard, can most effectively enable society to meet its GHG emissions reduction ambitions.

The Time Value of GHG emission reductions

The reality is that all pathways and all feedstocks are needed to achieve a lower carbon footprint for aviation fuels in a timeframe that meets the industry’s goal.  HEFA feedstocks represent a potential 70% (2) reduction in GHG emissions compared to conventional aviation fuel and can be scaled up today using existing technology for reliable supply to a critical industry. Importantly, industry can deliver GHG emissions reductions today while continuing to develop the next generation of SAF feedstock pathways. 

At ExxonMobil, we are celebrating 120 years of supplying quality fuel for the aviation industry. Today, we are developing advanced technology product solutions that continue to propel the industry forward through our leadership and expertise in R&D, manufacturing, and supply chain logistics.


2Compared to conventional aviation fuel using CORSIA Default Life Cycle Emissions Values.  Source: 

ICAO document 06 - Default Life Cycle Emissions - June 2022.pdf

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