This web story will cover just what is Sustainable Aviation Fuel, how it will be made and how it will be used in aviation?
The acronym for Sustainable Aviation Fuel is SAF. This product naming points to its likely replacement as a critical future aviation fuel. A key benefit of SAF is that it can be sourced from many non-traditional locales; most importantly, it can be sourced near urban areas where aviation is also centred.
SAF sources include biological sources, such as plant and animal materials, as well as from other sources, including non-biological sources such as textiles, packaging and industrial wastes. Figure 1 shows the several possible feedstock sources of Sustainable Aviation Fuel. A key feature noted in Figure 1 is the considerable emphasis on waste recovery to produce SAF.
Figure 1
Nextly, there are several conditions for fuels to meet in order to be considered sustainable. These conditions include lifecycle carbon emissions, conservation of fresh water, the absence of competition with food production, and as well avoiding deforestation. These combined requirements are a tall order to fill.
The global aviation industry clearly understands that it produces around 2% of all human-induced carbon dioxide (CO2) emissions. Consequently, it has made a series of short, medium and long-term climate action goals. In the short term, 1.5% average annual fuel efficiency improvements were proposed. The industry will then stabilize net aviation CO2 emissions at 2020 levels through carbon-neutral growth in the medium term. And in the long term, the sector will halve net CO2 emissions by 2050 – compared to 2005 levels. SAF is a crucial component of this plan throughout the three periods.
When considering SAF and carbon emissions, proponents believe that SAF can achieve up to 80% of CO2 lifecycle emission reductions. Also, SAF contains fewer other chemical impurities, such as sulphur, which reduces sulphur dioxide and related particulate matter emissions.
SAF was first used by the aviation industry in 2008 and has now powered over 250,000 flights worldwide. However, SAF fuel volumes currently remain very low, and less than 0.1% of the aviation fuel requirements are provided here. This weakness in supply calls for the development of supply chains and the establishment of community partners.
In 2011 SAF blended fuel with 50% biofuels were allowed on commercial flights. IATA is now aiming for a 2% SAF market penetration by 2025.
Further SAF deployment and testing were demonstrated in December 2021 when a Boeing 737 MAX 8 jet operated by United Airlines flew from Chicago’s – O’Hare Airport to Washington’s – Reagan National Airport with 115 people on board. On this occasion, it was the first commercial flight with passengers on board to use 100% drop-in[1] sustainable aviation fuel (SAF) for one of the aircraft’s two engines.[2]
Elsewhere in the industry, Airbus indicated in March 2022 that all of their aircraft were certified to fly using up to 50 percent SAF. Airbus aims to take things a step further by earning 100 percent SAF flight certification before 2030. [3]
Figure 2: Airbus A380 making its first SAF fuelled flight
Aviation industry leaders are beginning to understand that drop-in SAF is a very important answer between now and 2050 to reduce carbon emissions.
To this end, certain refiners, including Neste, have contracted with logistics provider DHL to provide approximately 105 million gallons of SAF over the next five years. While this seems like a lot of fuel, for context, in 2019, when global airline travel was at a peak, global fuel consumption was at an all-time high of 95 billion gallons. The U.S. aviation industry alone consumed just over 18 billion gallons.
This all points to a set of significant challenges that the Aviation Sector needs to make, has committed to, and is providing first-examples of how they will proceed.
[1] Drop-In fuel refers to SAF being a synthetic and completely interchangeable substitute for conventional petroleum-derived hydrocarbons (jet fuel in this case). This means that the fuel does not require adaptation of the engine, fuel system or the fuel distribution network and can be used as is.
[2] https://www.ge.com/news/reports/united-flies-worlds-first-passenger-flight-on-100-sustainable-aviation-fuel-supplying-one
[3] https://interestingengineering.com/a380-100-sustainable-fuel