Many of us remember the scene from the “Back to the Future” movie trilogy when Emmett “Doc” Brown used household garbage from Marty McFly’s trash can to power the “flux capacitor” on his time-traveling DeLorean. At the time, this was a fanciful invention for the entertainment of audiences around the world, but today there are real developments underway for using biomass as aviation jet fuel.
According to the U.S. Environmental Protection Agency, when we dispose of garbage in landfills, a large amount of methane comes out of the ground as the garbage decomposes. Methane accounts for 20% of global greenhouse gas (GHG) emissions and is 25 times more potent than carbon dioxide in trapping Earth’s heat. It follows that if we can convert biomass to a useful fuel product, we can significantly reduce GHGs. For jet aviation, that product is known as sustainable aviation fuel (SAF).
SAF blends components derived from renewable or waste-based biomass that, compared to today’s kerosene-based jet fuel, provides a significant reduction in GHG emissions. As stated by aviation sustainability company 4AIR, “SAF contains the same hydrocarbons (and thus the same tailpipe emissions) as fossil-based kerosene, but the difference is that the hydrocarbons came from a more sustainable source. This results in a net reduction of emissions when comparing to fossil jet fuel on a life cycle basis.” In essence, the SAF production life cycle means a reduction in overall emissions into the atmosphere.
The U.S. Department of Energy is working with other government and private agencies to establish an economical, drop-in fuel that is also practical, storable and deliverable in the existing supply chain. Several companies already collect waste products (such as used cooking oil from restaurants), process the waste and convert it to the building blocks of SAF; however, the cost to convert the biomass to fuel is estimated at three to six times higher than refining traditional jet fuel.
While costs to produce SAF are still considered high, the U.S. goal is to have at least 3 billion gallons of SAF available by 2030 and 35 billion gallons by 2050. In a statement from Sept. 9, 2021, the U.S. federal government called for partnerships with the private sector to achieve a rapid development and use of SAF.
Are airlines and airports on board?
In December 2021, United Airlines flew passengers from Chicago to Washington, D.C., using 100% SAF in one engine and regular Jet A in the other, proving that SAF can be a reliable fuel. Other airlines have signed contracts to purchase SAF as part of their efforts to reduce carbon emissions from their operations. According to Neste, one of the world’s largest producers of SAF, more than 40 airlines and 13 major airports worldwide already use and supply SAF, and its numbers are growing. SAF is already being used at some major U.S. airports, including Dallas-Fort Worth International, Los Angeles International and San Francisco International.
More recently, according to Aviation International News, the U.S. Air Force awarded a $65 million contract to SAF developer Air Company, which derives its SAF from carbon dioxide and water – with no need for a specific biomass other than air. After testing in an unmanned aerial vehicle, the Air Force noted that the new SAF is net-carbon neutral, “requiring as much captured carbon input as is emitted when the fuel is burned.” As the next step, the military is considering production and fueling facilities necessary to use the SAF in large quantities.
But at many civilian airports, the fueling system may not immediately lend itself to SAF use. If the airport has a hydrant system, in which the tenant airlines share the fuel supply, it might not be practical for only one airline to use SAF. Once the fuel is delivered to the airport, there is no differentiation during fueling operations as to which airline the fuel is delivered. To move forward, the airport would likely want all the airlines to agree to use (and pay for) the product. In addition, pure Jet A and pure SAF should be stored in separate tanks; a third tank would be needed for the combined, usable new fuel. This would allow control of the blend for SAF to be no more than 50% of the new SAF/Jet A fuel (as currently accepted). Finally, introducing SAF into the fuel storage facility would require recertification of the fuel, among other concerns.
Quality AND quantity
Beyond cost, the biggest challenge is meeting the demand. To meet an expanding commercial airline market, the production of SAF will need to match the existing availability of traditional kerosene-based jet fuel. This is no small hurdle. According to a Business Insider article, the U.S. produced about 4.5 million gallons of SAF in 2022, but the nation’s aviation fuel needs were 4.5 billion gallons. While many private companies are working to meet this huge challenge, the production capacity for SAF is still negligible compared to the economies of scale and supply chain benefits enjoyed by well-established facilities.
Over time and with private sector support, the SAF sustainability goals set by world government organizations may be met, but there is still plenty of work to be done.
Eric Menger is a business development manager at Hanson who can be reached at firstname.lastname@example.org.