TECHBRIEF

Greener Skies Could Be on the Horizon

As airlines explore approaches to decarbonize the aviation industry, sustainable aviation fuel has emerged as a leading sky-friendly solution.


In March 2021, Airlines for America boldly joined the decarbonization conversation. The trade organization that represents major U.S. airlines announced that its members had pledged to achieve net zero carbon emissions by 2050. One way to achieve this decarbonization goal is through increased production of sustainable aviation fuel (SAF) as an alternative for airlines to fuel their aircraft.

According to the U.S. Department of Energy, SAF is a biofuel that — just like conventional jet fuel — can fuel aircraft. However, one of the major benefits that separates SAF from conventional jet fuel is that its production has a smaller carbon footprint. SAF is produced from alternative, non-petroleum feedstocks, such as fats, oils and greases, farm residues, and municipal waste.

An additional benefit is that SAF is considered a drop-in fuel, meaning that with proper blending requirements in place it can be dropped directly into the existing fueling infrastructure and modern aircraft — no modifications needed.

 

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In March 2021, Airlines for America boldly joined the decarbonization conversation. The trade organization that represents major U.S. airlines announced that its members had pledged to achieve net zero carbon emissions by 2050. One way to achieve this decarbonization goal is through increased production of sustainable aviation fuel (SAF) as an alternative for airlines to fuel their aircraft.

According to the U.S. Department of Energy, SAF is a biofuel that — just like conventional jet fuel — can fuel aircraft. However, one of the major benefits that separates SAF from conventional jet fuel is that its production has a smaller carbon footprint. SAF is produced from alternative, non-petroleum feedstocks, such as fats, oils and greases, farm residues, and municipal waste.

An additional benefit is that SAF is considered a drop-in fuel, meaning that with proper blending requirements in place it can be dropped directly into the existing fueling infrastructure and modern aircraft — no modifications needed.

From Airlines to Refineries

As various airlines and federal government agencies seek out sustainable fueling options, conversations among oil refiners are shifting from the prospects of producing triglyceride-based renewable diesel to producing SAF using either fractionation or hydrocracking methods to meet growing demand.

While producing SAF might seem like an obvious win for the renewable fuels market, refiners could face an obstacle in the already-limited volume of triglyceride feedstock that is available today. From cover crops to waste grease and algae oil, there are some alternative pathways available, but given their limited quantities, triglycerides are unlikely able to meet SAF production needs to fully support the aviation industry’s net zero carbon goals.

Amid a deeper look into possible alternative feedstocks, there is a renewed interest in corn ethanol. This bio-based renewable feedstock is most commonly blended into gasoline to boost octane and lower the greenhouse gas emissions of light-duty vehicles. In anticipation of an ethanol surplus and reduced gasoline demand over time, the ethanol-to-jet pathway to SAF can be highly viable and is worth exploration. In addition to its availability, feedstock price is another advantage corn ethanol has over triglycerides within current market conditions.

Clearing SAF for Takeoff

Though the production and adoption rate of SAF may appear slow at this time, it is already being provided to a few major airports as a drop-in jet fuel. In December 2021, United Airlines completed the first commercial flight powered by 100% SAF. More than 100 passengers were along for the ride from Chicago O’Hare International Airport to Ronald Reagan Washington National Airport, arriving on time.

“Despite the demand for and excitement around SAF, bringing its high cost down will allow it to play an even bigger role in aviation fueling,” says Dan Eekhoff, an aviation project manager at Burns & McDonnell.

The U.S. Department of Energy, U.S. Department of Transportation, U.S. Department of Agriculture and other federal agencies have created the Sustainable Aviation Fuel Grand Challenge, a governmentwide Memorandum of Understanding that will work toward reducing costs, enhancing sustainability, and expanding the production and use of SAF. Part of this challenge aims to increase production of SAF from 180 million gallons currently to 3 billion gallons per year by 2030. If this lofty goal is met, SAF would replace close to 10% of conventional jet fuel sources.

Thought Leaders

Dave Collings

Senior Technical Advisory Consultant
1898 & Co.

Dan Eekhoff

Project Manager
Burns & McDonnell

Meaghan McCaffrey

Managing Director
Burns & McDonnell