Across the United States and around the world, there is a growing focus on renewable energy—energy collected from sources that can be more quickly replenished. Driving this trend is a focus on reducing carbon emissions and strengthening the global energy supply chain, making it shorter and more resilient. One major component of this trend is interest in sustainable aviation fuel (SAF).
SAF is a biofuel used to power aircraft. It has similar properties to conventional jet fuel, but a smaller carbon footprint. Depending on the feedstock and technologies used to produce it, SAF can greatly reduce life cycle greenhouse gas (GHG) emissions. It is a safe, reliable and low carbon alternative to standard jet fuel.
“The aviation industry is a huge energy consumer, so it is also a very large player in carbon being released into the atmosphere,” said Ron Obermoller, a member of the Agricultural Utilization Research Institute’s Board of Directors (representing the Minnesota Soybean Research and Promotion Council). “To be greener, they either need to buy credits or use fuels with better carbon scores.”
On a national scale, the U.S. Department of Energy is working with the U.S. Department of Transportation, the U.S. Department of Agriculture and other federal government agencies to develop a comprehensive strategy for scaling up new technologies to produce sustainable aviation fuel commercially.
To further emphasize a commitment to renewable energy, these agencies launched in 2021 the Sustainable Aviation Fuel Grand Challenge (Grand Challenge) in an effort to reduce the cost, enhance the sustainability and expand the production of and use of SAF, while accomplishing two main goals: (1) Achieving a minimum 50 percent reduction in life cycle greenhouse gas emissions compared to conventional fuel, and (2) Meeting a goal of supplying sufficient SAF to meet 100 percent of aviation fuel demand by 2050.
A regional example of this work is the Commercial Aviation Alternative Fuels Initiative (CAAFI), launched in 2006, which is working to enhance energy security and environmental sustainability for aviation using alternative jet fuels. CAAFI is a coalition of airlines, aircraft and engine manufacturers, energy producers, researchers, international participants and U.S. government agencies. Together, they lead the development and deployment of alternative jet fuels for commercial aviation.
Steve Csonka, Executive Director of CAAFI, says the organization’s goal is to promote the development of alternative jet fuel options that offer equivalent safety and reasonable costs compared to petroleum-based jet fuel, while offering environmental improvement and energy supply security for the aviation industry.
According to CAAFI, volatility in petroleum prices caused fuel to become the single largest component of U.S. airline operating costs for the first time in history in 2006. Csonka states that while U.S. commercial aviation consumes about three percent of the United States’ total energy use, it drives about six percent of the U.S. gross domestic product and just under nine percent of national employment. “Secure and sustainable fuel sources are essential for its continued prosperity to the benefit of the American people,” he said.
Through chemical and biochemical processes, renewable jet fuel is derived from a variety of natural sources, including oils, greases, sugars, starches, waste streams and byproducts. The market size in the U.S. is 26 billion gallons per year, while the worldwide market size is 97 billion gallons per year. According to Csonka, jet fuel demand is expected to increase 3-5 percent per year for the foreseeable future, following a rebound from the COVID-19 pandemic.
CAAFI believes aviation is international in scope, highly integrated in its fuel supply chain and, because of a significant ability to align and coordinate within the industry, well positioned to pursue alternative fuels.
The biggest challenge to the production and commercialization of SAF is cost, with current sources costing twice as much as standard jet fuel, and with additional sources (in their infancy) costing more. Additionally, the projected cost of synthetic fuels using carbon-capture are even higher.
Reducing these costs will require investment in advanced technologies to process feedstocks more efficiently at a greater scale, as well as investment in the development of sustainable and scalable feedstock options.
According to Air bp, sustainable aviation fuel delivers greenhouse gas reductions of up to 80 percent over the traditional jet fuel it replaces, providing additional environmental benefits. CAAFI indicates there are SAF production pathways that can deliver more than 100 percent reductions (carbon negative fuels) when incorporating renewable power, renewable hydrogen and carbon capture and sequestration. Therefore, SAF plays a significant role in the airline industry’s carbon reduction targets.
Sustainable aviation fuel is a benefit to farmers by utilizing their crops and biomass production, and if cash cover crops are utilized, they provide the added benefit of helping reduce nutrient loss and improving soil quality.
In addition to reducing carbon emissions, biomass crops and cash cover crops that produce oil seeds (e.g.: pennycress, carinata, camelina) help control erosion and improve water quality. They also provide biodiversity and store carbon in the soil. Currently, the aviation industry recognizes seven processes for the production of SAF, with several more being evaluated for approval. These processes already enable the use of fats, oils, greases, starches, sugars, biomass and circular-economy byproducts and waste streams for use in SAF.
In addition, producing SAF from municipal solid waste and wet wastes, like manure and sewage sludge, reduces pollution, while also keeping methane gas out of the atmosphere.
The aviation industry and governments around the world are working to foster, catalyze, enable and facilitate the production and commercialization of sustainable aviation fuel by removing barriers and identifying pathways for fully synthetic SAF (50 percent max blend), as well as by enhancing the SAF value proposition by enabling deeper net-carbon reductions. They are also pursuing commercial agreements fostered by policy and other unique approaches.
While there is a great commitment to reduce carbon emissions, it will take even more work by governments and researchers to accelerate the growth of SAF. The CAAFI, AURI, public and private researchers and other local, state and national agencies continue to make headway in this growing industry.
“Think about the magnitude in front of us. It’s [SAF] a 100 billion gallon per year market and this past year as an industry we produced 8 million gallons, so we have a lot of runway in front of us,” said Csonka.