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Anaviation biofuel (also known asbio-jet fuel,[1]sustainable aviation fuel (SAF), orbio-aviation fuel (BAF)[2]) is abiofuel used to poweraircraft. TheInternational Air Transport Association (IATA) considers it a key element in reducing theenvironmental impact of aviation.[3] Aviation biofuel is used todecarbonize medium and long-haul air travel. These types of travel generate the most emissions and could extend the life of older aircraft types by lowering their carbon footprint.Synthetic paraffinic kerosene (SPK) refers to any non-petroleum-based fuel designed to replace kerosenejet fuel, which is often, but not always, made from biomass.
Biofuels arebiomass-derived fuels from plants, animals, or waste; depending on which type of biomass is used, they could lowerCO2 emissions by 20–98% compared toconventional jet fuel.[4]The first test flight using blended biofuel was in 2008, and in 2011, blended fuels with 50% biofuels were allowed on commercial flights. In 2023 SAF production was 600 million liters, representing 0.2% of global jet fuel use.[5] By 2024, SAF production was to increase to 1.3 billion liters (1 million tonnes), representing 0.3% of global jet fuel consumption and 11% of global renewable fuel production.[6] This increase came as major US production facilities delayed their ramp-up until 2025, having initially been expected to reach 1.9 billion liters.
Aviation biofuel can be produced from plant or animal sources such asJatropha,algae,tallows, waste oils,palm oil,Babassu, andCamelina (bio-SPK); from solidbiomass usingpyrolysis processed with aFischer–Tropsch process (FT-SPK); with analcohol-to-jet (ATJ) process from waste fermentation; or fromsynthetic biology through asolar reactor. Small piston engines can be modified to burnethanol.
Sustainable biofuels are an alternative toelectrofuels.[7] Sustainable aviation fuel is certified as beingsustainable by a third-party organisation[citation needed].
SAF technology faces significant challenges due to feedstock constraints. The oils and fats known as hydrotreated esters and fatty acids (Hefa), crucial for SAF production, are in limited supply as demand increases. Although advancede-fuels technology, which combines wasteCO2 withclean hydrogen, presents a promising solution, it is still under development and comes with high costs. To overcome these issues, SAF developers are exploring more readily available feedstocks such aswoody biomass and agricultural and municipal waste, aiming to produce lower-carbon jet fuel more sustainably and efficiently.[8][9]
Plants absorbcarbon dioxide as they grow, therefore plant-based biofuels emit only the same amount ofgreenhouse gases as they had previously absorbed. Biofuel production, processing, and transport, however, emit greenhouse gases, reducing the emissions savings.[2] Biofuels with the most emission savings are those derived from photosynthetic algae (98% savings) although the technology is not developed, and those fromnon-food crops and forest residues (91–95% savings).[2]
Jatropha oil, a non-food oil used as a biofuel, lowersCO2 emissions by 50–80% compared to Jet-A1, akerosene-based fuel.[10] Jatropha, used forbiodiesel, can thrive onmarginal land where most plants produce lowyields.[11][12] Alife cycle assessment on jatropha estimated that biofuels could reduce greenhouse gas emissions by up to 85% if former agro-pastoral land is used, or increase emissions by up to 60% if natural woodland is converted.[13]
Palm oil cultivation is constrained by scarce land resources and its expansion to forestland causesbiodiversity loss, along with direct and indirect emissions due toland-use change.[2]Neste Corporation's renewable products include a refiningresidue of food-grade palm oil, the oily wasteskimmed from the palm oil mill'swastewater. Other Neste sources areused cooking oil fromdeep fryers and animal fats.[14]Neste's sustainable aviation fuel is used byLufthansa;[15]Air France andKLM announced 2030 SAF targets in 2022[16] including multi-year purchase contracts totaling over 2.4 million tonnes of SAF from Neste,TotalEnergies, andDG Fuels.[17]
Aviation fuel from wet waste-derived feedstock ("VFA-SAF") provides an additional environmental benefit. Wet waste consists of waste from landfills, sludge from wastewater treatment plants, agricultural waste, greases, and fats. Wet waste can be converted to volatile fatty acids (VFA's), which then can be catalytically upgraded to SAF. Wet waste is a low-cost and plentiful feedstock, with the potential to replace 20% of US fossil jet fuel.[18] This lessens the need to grow crops specifically for fuel, which in itself is energy intensive and increasesCO2 emissions throughout its life cycle. Wet waste feedstocks for SAF divert waste from landfills. Diversion has the potential to eliminate 17% of US methane emissions across all sectors. VFA-SAF's carbon footprint is 165% lower than fossil aviation fuel.[18] This technology is in its infancy; although start-ups are working to make this a viable solution. Alder Renewables, BioVeritas, and ChainCraft are a few organizations committed to this.
NASA has determined that 50% aviation biofuel mixture can cutparticulate emissions caused by air traffic by 50–70%.[19] Biofuels do not contain sulfur compounds and thus do not emitsulfur dioxide.[citation needed]
 | This section needs to beupdated. The reason given is: Lots of plans announced years ago. No info on whether the plans were carried out.. Please help update this article to reflect recent events or newly available information.(March 2024) |
The first flight using blendedbiofuel took place in 2008.[20]Virgin Atlantic used it fly a commercial airliner, using feedstocks such asalgae.[21] Airlines representing more than 15% of the industry formed the Sustainable Aviation Fuel Users Group, with support from NGOs such asNatural Resources Defense Council andThe Roundtable For Sustainable Biofuels by 2008. They pledged to developsustainable biofuels for aviation.[22] That year, Boeing was co-chair of theAlgal Biomass Organization, joined by air carriers and biofuel technology developerUOP LLC (Honeywell).[23]
In 2009, the IATA committed to achievingcarbon-neutral growth by 2020, and to halve carbon emissions by 2050.[24]
In 2010, Boeing announced a target 1% of global aviation fuels by 2015.[25]
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By June 2011, the revisedSpecification for Aviation Turbine Fuel Containing Synthesized Hydrocarbons (ASTM D7566) allowed commercial airlines to blend up to 50% biofuels with conventional jet fuel.[26] The safety and performance of jet fuel used in passenger flights is certified byASTM International.[27] Biofuels were approved for commercial use after a multi-year technical review fromaircraft makers,engine manufacturers andoil companies.[28] Thereafter some airlines experimented with biofuels on commercial flights.[29] As of July 2020, seven annexes to D7566 were published, including various biofuel types:[30]
In December 2011, theFAA awarded US$7.7 million to eight companies to developdrop-in sustainable fuels, especially fromalcohols, sugars,biomass, andorganic matter such aspyrolysis oils, within itsCAAFI andCLEEN programs.[31]
Biofuel provider Solena filed for bankruptcy in 2015.[32]
By 2015, cultivation offatty acid methyl esters andalkenones from the algae,Isochrysis, was under research.[33]
By 2016, Thomas Brueck ofMunich TU was forecasting thatalgaculture could provide 3–5% of jet fuel needs by 2050.[34]
In fall 2016, theInternational Civil Aviation Organization announced plans for multiple measures including the development and deployment of sustainable aviation fuels.[35]
Dozens of companies received hundreds of millions inventure capital from 2005 to 2012 to extract fuel oil from algae, some promising competitively-priced fuel by 2012 and production of 1 billion US gal (3.8 million m3) by 2012-2014.[36] By 2017 most companies had disappeared or changed theirbusiness plans to focus on other markets.[36]
In 2019, 0.1% of fuel was SAF:[37] TheInternational Air Transport Association (IATA) supported the adoption of Sustainable Aviation fuel, aiming in 2019 for 2% share by 2025: 7 million m3 (1.8 billion US gal).[38][20]
In early 2021, Boeing's CEODave Calhoun said drop-insustainable aviation fuels are "the only answer between now and 2050" to reduce carbon emissions.[40] In May 2021, theInternational Air Transport Association (IATA) set a goal for the aviation industry to achieve net-zero carbon emissions by 2050 with SAF as the key component.[41]
The 2022Inflation Reduction Act introduced the Fueling Aviation's Sustainable Transition (FAST) Grant Program. The program provides $244.5 million in grants for SAF-related "production, transportation, blending, and storage."[42] In November, 2022, sustainable aviation fuels were a topic atCOP26.[43]
As of 2023, 90% of biofuel was made from oilseed and sugarcane which are grown for this purpose only.[44]
Jet fuel is a mixture of varioushydrocarbons. The mixture is restricted by product requirements, for example,freezing point andsmoke point. Jet fuels are sometimes classified askerosene ornaphtha-type. Kerosene-type fuels include Jet A, Jet A-1, JP-5 and JP-8. Naphtha-type jet fuels, sometimes referred to as "wide-cut" jet fuel, include Jet B and JP-4.
"Drop-in" biofuels are biofuels that are interchangeable with conventional fuels. Deriving "drop-in" jet fuel from bio-based sources isASTM approved via two routes. ASTM has found it safe to blend in 50% SPK into regular jet fuels.[45][27] Tests have been done with blending synthetic paraffinic kerosene (SPK) in considerably higher concentrations.[46]
Systems that usesynthetic biology to create hydro-carbons are under development:
Small piston engines can be modified to burnethanol.[66]Swift Fuel, a biofuel alternative toavgas, was approved as a test fuel byASTM International in December 2009.[67][68]
Nitrile-based rubber materials expand in the presence of aromatic compounds found in conventional petroleum fuel. Pure biofuels without petroleum and paraffin-based additives may cause rubber seals and hoses to shrink.[69] Synthetic rubber substitutes that are not adversely affected by biofuels, such asViton, for seals and hoses are available.[70]
TheUnited States Air Force found harmful bacteria and fungi in their biofueled aircraft, and usepasteurization to disinfect them.[71]
As of May 2025[update] SAF is generally required to be blended with fossil fuel—because jet fuel needscycloalkanes andaromatics, which are generally deficient in SAF; as well as the more prevalent in SAFn-alkanes andisoalkanes.[72]
In 2019 theInternational Energy Agency forecast SAF production should grow from 18 to 75 billion litres between 2025 and 2040, representing a 5% to 19% share of aviation fuel.[20] By 2019, fossil jet fuel production cost was $0.3-0.6 per L given a $50–100 crudeoil barrel, while aviation biofuel production cost was $0.7-1.6, needing a $110–260 crude oil barrel tobreak-even.[20]
As of 2020[update] aviation biofuel was more expensive than fossil jet kerosene,[1] consideringaviation taxation and subsidies at that time.[73]
As of a 2021 analysis, VFA-SAF break-even cost was $2.50/US gal ($0.66/L).[18] This number was generated considering credits and incentives at the time, such asCalifornia's LCFS (Low Carbon Fuel Standard) credits and the US Environmental Protection Agency (EPA)Renewable Fuel Standard incentives.
Sustainable biofuels do not usefood crops, primeagricultural land or fresh water.Sustainable aviation fuel (SAF) is certified by a third-party such as theRoundtable For Sustainable Biofuels.[74]
As of 2022, some 450,000 flights had used sustainable fuels as part of the fuel mix, although such fuels were ~3x more expensive than the traditional fossil jet fuel orkerosene.[75] In 2023, SAFs account for less than 0.1% of all aviation fuels consumed.[76] Throughout 2024,Alaska Airlines was the leader among U.S. airlines in SAF implementation, accounting for 0.68% of its fuel usage. Other major airlines including United, Delta and JetBlue used SAF in roughly .3% of fuel.[51]
A SAF sustainability certification ensures that the product satisfies criteria focused on environmental, social, and economic "triple-bottom-line" considerations. Under many emission regulation schemes, such as theEuropean Union Emissions Trading Scheme (EUTS), a certified SAF product may be exempted from carbon compliance liability costs.[77] This marginally improves SAF's economic competitiveness versus fossil-based fuel.[78]
The first reputable body to launch a sustainable biofuel certification system was the European-based Roundtable on Sustainable Biomaterials (RSB) NGO.[79] Leading airlines and other signatories to the Sustainable Aviation Fuel Users Group (SAFUG) pledged to support RSB as their preferred certification provider.[80][81]
Some SAF pathways procuredRIN pathways under the United States'srenewable fuel standard which can serve as an implicit certification if the RIN is aQ-RIN.
Asemissions trading schemes and other carbon compliance regimes emerge, certain biofuels are likely to be exempted ("zero-rated") by governments from compliance due to their closed-loop nature, if they can demonstrate appropriate credentials. For example, in the EUTS, SAFUG's proposal was accepted[83] that only fuels certified as sustainable by the RSB or similar body would be zero-rated.[84] SAFUG was formed by a group of interested airlines in 2008 under the auspices ofBoeing Commercial Airplanes. Member airlines represented more than 15% of the industry, and signed a pledge to work towards SAF.[85][86]
In addition to SAF certification, the integrity of aviation biofuel producers and their products could be assessed by means such asRichard Branson's Carbon War Room,[87] or the Renewable Jet Fuels initiative.[88] The latter works with companies such as LanzaTech, SG Biofuels, AltAir, Solazyme, and Sapphire.[89][verification needed]
Along with her co-authors,Candelaria Bergero of theUniversity of California'sEarth System Science Department stated that "main challenges to scaling up such sustainable fuel production include technology costs and process efficiencies", and widespread production would underminefood security andland use.[90]
By 2019,Virgin Australia had fueled more than 700 flights and flown more than one million kilometers, domestic and international, usingGevo's alcohol-to-jet fuel.[91]Virgin Atlantic was working to regularly use fuel derived from the waste gases ofsteel mills, withLanzaTech.[92]British Airways wanted to convert household waste into jet fuel withVelocys.[92]United Airlines committed to 900 million US gal (3,400,000 m3) of sustainable aviation fuel for 10 years from Fulcrum BioEnergy (of its 4.1 billion US gal (16,000,000 m3) fuel consumption in 2018), after a $30 million investment in 2015.[92]
From 2020,Qantas planned to use a 50/50 blend of SG Preston's biofuel on its Los Angeles-Australia flights. SG Preston also planned to provide fuel toJetBlue over 10 years.[92] At its sites inSingapore,Rotterdam andPorvoo, Finland'sNeste expected to improve its renewable fuel production capacity from 2.7 to 3.0 million t (6.0 to 6.6 billion lb) a year by 2020, and to increase its Singapore capacity by 1.3 million t (2.9 billion lb) to reach 4.5 million t (9.9 billion lb) in 2022 by investing €1.4 billion ($1.6 billion).[92]
By 2020,International Airlines Group had invested $400 million to convert waste into sustainable aviation fuel withVelocys.[93]
United Airlines has expanded SAF use across multiple airports worldwide, includingAmsterdam in 2022,[94]San Francisco andLondon in 2023,[95] andChicago O'Hare andLos Angeles in 2024.[96]
In March 2024, regular use of SAF began in the Northeastern United States atJohn F. Kennedy International Airport, as part of a new effort by JetBlue.[97]Southwest Airlines began using sustainable jet fuel atChicago Midway International Airport in October 2024.[98]
| Abbreviation | Conversion Process | Possible Feedstocks | Blending Ratio | Commercialization Proposals / Projects |
|---|---|---|---|---|
| HEFA-SPK | Synthesized paraffinic kerosene produced from hydroprocessed esters and fatty acids | Bio-Oils, Animal Fat, Recycled Oils | 50% | World Energy,Universal Oil Products,Neste, Dynamic Fuels, EERC |
| FT-SPK | Fischer-Tropsch hydroprocessed synthesized paraffinic kerosene | Coal, Natural Gas, Biomass | 50% | Fulcrum Bioenergy, Red Rock Biofuels, SG Preston,Kaidi Finland,Sasol,Shell Oil Company,Syntroleum |
| SIP-HFS | Synthesized kerosene isoparaffins produced from hydroprocessed fermented sugars | Biomass-derived sugar | 10% | Amyris (company),TotalEnergies |
| SPK/A | Synthesized kerosene with aromatics derived by alkylation of light aromatics from non-petroleum sources | Coal, Natural Gas, Biomass | 50% | Sasol |
| ATJ-SPK | Alcohol-to-jet synthetic paraffinic kerosene | Biomass-derived ethanol or isobutanol | 50% | Gevo, Cobalt,Universal Oil Products, Lanzatech, Swedish Biofuels, Byogy |
D7566 Revision Adds Bioderived Components
{{cite web}}: CS1 maint: numeric names: authors list (link){{cite web}}: CS1 maint: archived copy as title (link)Alcohol-to-Jet Synthetic Paraffinic Kerosene Is a Proven Pathway to Deliver a Bio-Based, Low-Carbon Option to Travelers
Sustainable Aviation Fuels as a Pathway to Net-Zero Aviation
non-profit think tank/do tank focused on [...] the market transformation of the world's air transport system towards a [...] sustainable long-term future
Nordic association working to promote and develop a more sustainable aviation industry, with a specific focus on alternative sustainable fuels
The RSB is supporting the development of a sustainable bioeconomy