View source for Aviation biofuel

{{Short description|Sustainable fuel used to power aircraft}}
<section begin="summary" />
[[File:Refuel EC-KNM Iberia (6218464950).jpg|thumb|upright=1.2|Refueling an [[Airbus A320]] with [[biofuel]] in 2011]]

An '''aviation biofuel''' (also known as '''bio-jet fuel'''<ref name=IU4dec2020>{{Cite web |date= 2020-12-04 |access-date= 2022-12-12|title= Sustainable aviation fuel market demand drives new product launches |url=https://investableuniverse.com/2020/12/04/sustainable-aviation-fuel-argus-price-gunvor-group/ |website= [[Investable Universe]]}} Note: ''[https://investableuniverse.com/home/about/ Investable Universe>About]''</ref> or '''bio-aviation fuel''' (BAF)<ref name="Doliente2020">{{Cite journal |last= Doliente |first= Stephen S. |display-authors=etal |date= 10 July 2020 |title= Bio-aviation Fuel: A Comprehensive Review and Analysis of the Supply Chain Components |journal= Frontiers in Energy Research |volume= 8 |doi= 10.3389/fenrg.2020.00110 |language= English |doi-access= free |url= https://purehost.bath.ac.uk/ws/files/205375761/Doliente_et_al_2020_Accepted_Manuscript_Frontiers_in_Energy_Research.pdf }}</ref>) is a [[biofuel]] used to power [[aircraft]] and is a [[Aviation biofuel#Sustainable aviation fuels|sustainable aviation fuel]] (SAF).<!-- is this correct?? it seems wrong to say that aviation biofuel is SAF --> The [[International Air Transport Association]] (IATA) considers it a key element in reducing the [[environmental impact of aviation]].<ref>{{cite web |url= https://www.iata.org/en/programs/environment/sustainable-aviation-fuels/ |title= Developing Sustainable Aviation Fuel (SAF) |publisher= IATA}}</ref> Aviation biofuel is used to [[Low-carbon economy|decarbonize]] 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 kerosene [[jet fuel]], which is often, but not always, made from biomass.

<!--Environmental impact-->
Biofuels are [[biomass]]-derived fuels from plants, animals, or waste; depending on which type of biomass is used, they could lower {{chem2|CO2}} emissions by 20–98% compared to [[Jet A1|conventional jet fuel]].<ref name="Bauen2009">{{cite CiteSeerX |last1=Bauen |first1=Ausilio |first2=Jo |last2=Howes |first3=Luca |last3=Bertuccioli |first4=Claire |last4=Chudziak |title=Review of the potential for biofuels in aviation |date= August 2009|citeseerx=10.1.1.170.8750 }}</ref>
<!--Timeline-->The first test flight using blended biofuel was in 2008,<!--ref name=IEA18mar2019/--> 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.<ref>{{Cite web |last=IATA |date=December 2023 |title=Net zero 2050: sustainable aviation fuels – December 2023 |url=https://www.iata.org/en/iata-repository/pressroom/fact-sheets/fact-sheet---alternative-fuels/#:~:text=Aviation%20fuel%20suppliers%20will%20have,rising%20to%2070%25%20in%202050. |archive-url=https://web.archive.org/web/20240224104907/https://www.iata.org/en/iata-repository/pressroom/fact-sheets/fact-sheet---alternative-fuels/ |archive-date=24 February 2024 |website=www.iata.org/flynetzero}}</ref><!--ref name=ASTMsep2011--><!--ref name=IATAmay2019-->

<!--Production-->
Aviation biofuel can be produced from plant or animal sources such as ''[[Jatropha]]'', [[algae]], [[tallows]], waste oils, [[palm oil]], [[Babassu oil|Babassu]], and ''[[Camelina]]'' (bio-SPK); from solid [[biomass]] using [[pyrolysis]] processed with a [[Fischer–Tropsch process]] (FT-SPK); with an [[Alcohol (chemistry)|alcohol]]-to-jet (ATJ) process from waste fermentation; or from [[synthetic biology]] through a [[Chemical reactor|solar reactor]]. Small piston engines can be modified to burn [[ethanol]].<!--ref name=SDSU2016-->

<!--Sustainable fuels-->
[[Sustainable biofuel]]s are an alternative to [[electrofuels]].<ref>{{Cite web|author=Mark Pilling|title=How sustainable fuel will help power aviation's green revolution|url=https://www.flightglobal.com/flight-international/how-sustainable-fuel-will-help-power-aviations-green-revolution/143044.article|date=2021-03-25|website=Flight Global}}</ref> Sustainable aviation fuel is certified as being [[sustainable]] by a third-party organisation.<section end="summary" />

{{TOCLimit}}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 advanced [[Electrofuel|e-fuels]] technology, which combines waste {{Chem2|CO2}} with [[Green hydrogen|clean 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 as [[Lignocellulosic biomass|woody biomass]] and agricultural and municipal waste, aiming to produce lower-carbon jet fuel more sustainably and efficiently.<ref>{{Cite web |date=2024-05-10 |title=New Technology Helps Advance Non-Hefa SAF Projects |url=https://www.energyintel.com/0000018f-5ac5-d00d-a7df-7ff56da40000 |access-date=2024-05-14 |website=Energy Intelligence |language=en}}</ref><ref>{{Cite web |date=2024-08-14 |title=New SAF Process Could Transform Industry |url=https://www.ainonline.com/aviation-news/aerospace/2024-08-14/new-saf-process-could-transform-industry |access-date=2024-08-14 |website=Aviation Industry News |language=en}}</ref>

==Environmental impact==
{{further|Environmental impact of aviation|Biofuel#Greenhouse gas emissions}}

Plants absorb [[Carbon Dioxide|carbon dioxide]] as they grow, therefore plant-based biofuels emit only the same amount of [[greenhouse gas]]es as they had previously absorbed. Biofuel production, processing, and transport, however, emit greenhouse gases, reducing the emissions savings.<ref name="Doliente2020" /> Biofuels with the most emission savings are those derived from photosynthetic algae (98% savings) although the technology is not developed, and those from [[Second-generation biofuels|non-food crops and forest residues]] (91–95% savings).<ref name="Doliente2020" />

[[Jatropha oil]], a non-food oil used as a biofuel, lowers {{chem2|CO2}} emissions by 50–80% compared to Jet-A1, a [[kerosene]]-based fuel.<ref name=AImar2009>{{cite magazine |title= A Greener Future? |magazine= [[Aircraft Illustrated]] |date= March 2009}}</ref> Jatropha, used for [[biodiesel]], can thrive on [[marginal land]] where most plants produce low [[crop yield|yield]]s.<ref>{{cite news |author= Ron Oxburgh |url= https://www.theguardian.com/commentisfree/2008/feb/28/alternativeenergy.biofuels |title= Through biofuels we can reap the fruits of our labours |newspaper= [[The Guardian]] |date= 28 February 2008}}</ref><ref>{{cite news |author= Patrick Barta |title= As Biofuels Catch On, Next Task Is to Deal With Environmental, Economic Impact |url= https://www.wsj.com/articles/SB120631198956758087 |newspaper= [[Wall Street Journal]] |date= 24 March 2008 |url-access= subscription}}</ref> A [[life 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.<ref>{{Cite journal | last1 = Bailis | first1 = R. E. | last2 = Baka | first2 = J. E. | doi = 10.1021/es1019178 | title = Greenhouse Gas Emissions and Land Use Change from Jatropha Curcas-Based Jet Fuel in Brazil | journal = Environmental Science & Technology | volume = 44 | issue = 22 | pages = 8684–91 | year = 2010 | pmid = 20977266| bibcode = 2010EnST...44.8684B }}</ref>

[[Palm oil]] cultivation is constrained by scarce land resources and its expansion to forestland causes [[biodiversity loss]], along with direct and indirect emissions due to [[land-use change]].<ref name="Doliente2020" /> [[Neste Corporation]]'s renewable products include a refining [[byproduct|residue]] of food-grade palm oil, the oily waste [[Resource recovery|skimmed]] from the palm oil mill's [[wastewater]]. Other Neste sources are [[used cooking oil]] from [[Deep fryer#Oil filtration|deep fryers]] and animal fats.<ref>{{Cite web|url=https://www.neste.com/products/all-products/raw-materials/waste-and-residues|title=Waste and residues as raw materials |date=15 May 2020 |publisher=Neste Corporation website}}</ref> [https://www.neste.com/en-us/products-and-innovation/sustainable-aviation/sustainable-aviation-fuel Neste's sustainable aviation fuel] is used by [[Lufthansa]];<ref>{{Cite press release|url=https://www.neste.com/releases-and-news/aviation/neste-and-lufthansa-collaborate-and-aim-more-sustainable-aviation|title=Neste and Lufthansa collaborate and aim for a more sustainable aviation|date=October 2, 2019|publisher=Neste Corporation website}}</ref> [[Air France]] and [[KLM]] announced 2030 SAF targets in 2022<ref>{{Cite press release|url=https://news.klm.com/klm-groups-co2-emission-reduction-targets-for-2030-approved-by-sbti/|title=KLM Group's CO2 emission reduction targets for 2030 approved by SBTi|date=16 December 2022 |publisher=KLM website |access-date=2023-01-02}}</ref> including multi-year purchase contracts totaling over 2.4 million tonnes of SAF from Neste, [[TotalEnergies]], and [[DG Fuels]].<ref>{{Cite news| url=https://www.reuters.com/business/energy/totalenergies-air-france-klm-agree-sustainable-jet-fuel-deal-2022-12-05/|title=TotalEnergies and Air France KLM agree sustainable jet fuel deal|date=5 December 2022 |publisher=[[Reuters]] |access-date=2023-01-02}}</ref>

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.<ref name="auto">{{Cite journal |last1=Huq |first1=Nabila A. |last2=Hafenstine |first2=Glenn R. |last3=Huo |first3=Xiangchen |last4=Nguyen |first4=Hannah |last5=Tifft |first5=Stephen M. |last6=Conklin |first6=Davis R. |last7=Stück |first7=Daniela |last8=Stunkel |first8=Jim |last9=Yang |first9=Zhibin |last10=Heyne |first10=Joshua S. |last11=Wiatrowski |first11=Matthew R. |last12=Zhang |first12=Yimin |last13=Tao |first13=Ling |last14=Zhu |first14=Junqing |last15=McEnally |first15=Charles S. |date=2021-03-30 |title=Toward net-zero sustainable aviation fuel with wet waste-derived volatile fatty acids |journal=Proceedings of the National Academy of Sciences of the United States of America |volume=118 |issue=13 |pages=e2023008118 |doi=10.1073/pnas.2023008118 |issn=1091-6490 |pmc=8020759 |pmid=33723013 |doi-access=free |bibcode=2021PNAS..11823008H }}</ref> This lessens the need to grow crops specifically for fuel, which in itself is energy intensive and increases {{chem2|CO2}} 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.<ref name="auto"/> 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 cut [[particulate emissions]] caused by air traffic by 50–70%.<ref>{{cite news |url= http://www.flyingmag.com/nasa-confirms-biofuels-reduce-jet-emissions |work= [[Flying (magazine)|Flying magazine]] |title= NASA confirms biofuels reduce jet emissions |date= March 23, 2017}} Note: Firefox 'does not trust' the weblink 2022-12-22.</ref> Biofuels do not contain sulfur compounds and thus do not emit [[sulfur dioxide]].{{Citation needed|date=December 2022}}

==History==
{{see also|Aviation biofuel demonstrations}}{{Update section|date=March 2024|reason=Lots of plans announced years ago. No info on whether the plans were carried out.}}
The first flight using blended [[biofuel]] took place in 2008.<ref name="IEA18mar2019" /> [[Virgin Atlantic]] used it fly a commercial airliner, using feedstocks such as [[algae]].<ref>{{cite news |url= http://news.bbc.co.uk/2/hi/7261214.stm |work=[[BBC News]]|title= First biofuel flight touches down |date= 24 February 2008}}</ref> Airlines representing more than 15% of the industry formed the Sustainable Aviation Fuel Users Group, with support from NGOs such as [[Natural Resources Defense Council]] and [[Sustainable biofuel#Roundtable on Sustainable Biomaterials|The Roundtable For Sustainable Biofuels]] by 2008. They pledged to develop [[sustainable biofuels]] for aviation.<ref>{{cite news |title=Our Commitment to Sustainable Options |url=https://www.boeing.com/aboutus/environment/environmental_report_09/_inc/3.4.3-Sustainable-Aviation-Fuel-Users-group.pdf |access-date= |publisher=Sustainable Aviation Fuel Users Group}}{{dead link|date=April 2024}}</ref> That year, Boeing was co-chair of the [[Algal Biomass Organization]], joined by air carriers and biofuel technology developer [[UOP LLC]] (Honeywell).<ref>{{cite news |url= http://www.greencarcongress.com/2008/06/first-airlines.html |title= First Airlines and UOP Join Algal Biomass Organization |work= Green Car Congress |date= 19 June 2008}}</ref>

In 2009, the IATA committed to achieving [[carbon-neutral]] growth by 2020, and to halve carbon emissions by 2050.<ref>{{cite press release |url= https://www.iata.org/en/pressroom/pr/2009-06-08-03/ |title= Carbon-Neutral Growth By 2020 |publisher= IATA |date= 8 June 2009 |access-date= 2020-12-06 |archive-date= 2021-04-14 |archive-url= https://web.archive.org/web/20210414025050/https://www.iata.org/en/pressroom/pr/2009-06-08-03/ |url-status= dead }}</ref>

In 2010, Boeing announced a target 1% of global aviation fuels by 2015.<ref>{{cite news |url= https://www.bloomberg.com/news/2010-07-22/commercial-airlines-may-get-1-of-fuel-from-biofuels-by-2015-boeing-says.html |title= Airlines May Get 1% of Fuel From Biofuels By 2015, Boeing Says |date=22 July 2010 |agency= Bloomberg}}</ref>

[[File:US Navy 110921-N-ZZ999-002 An AV-8B Harrier assigned to Air Test and Evaluation Squadron (VX) 31 conducts the first test flight of a mix of 50-50 j.jpg|thumb|upright|US Marine Corps [[AV-8B Harrier II]] test flight using a 50–50 biofuel blend in 2011]]

By June 2011, the revised ''Specification for Aviation Turbine Fuel Containing Synthesized Hydrocarbons'' ([[ASTM]] D7566) allowed commercial airlines to blend up to 50% biofuels with conventional jet fuel.<ref>{{cite news |url=http://www.renewableenergyworld.com/rea/news/article/2011/07/50-percent-biofuels-now-allowed-in-jet-fuel |title=50 Percent Biofuels Now Allowed in Jet Fuel |date=1 July 2011 |work=[[Renewable Energy World]] |access-date=6 December 2020 |archive-date=8 June 2020 |archive-url=https://web.archive.org/web/20200608062153/https://www.renewableenergyworld.com/2011/07/01/50-percent-biofuels-now-allowed-in-jet-fuel/ |url-status=dead }}</ref> The safety and performance of jet fuel used in passenger flights is certified by [[ASTM International]].<ref name=ASTMsep2011>{{cite web |url= http://www.astm.org/SNEWS/SO_2011/enright_so11.html |title= Aviation Fuel Standard Takes Flight |quote= D7566 Revision Adds Bioderived Components |publisher= ASTM |date= September–October 2011}}</ref> Biofuels were approved for commercial use after a multi-year technical review from [[Aerospace manufacturer|aircraft maker]]s, [[List of turbofan manufacturers|engine manufacturer]]s and [[oil companies]].<ref>{{cite news |url= https://www.bloomberg.com/news/2011-07-01/airlines-win-approval-to-use-plant-based-biofuels-on-commercial-flights.html |title= Airlines Win Approval to Use Biofuels for Commercial Flights |date= 1 July 2011 |agency= Bloomberg}}</ref> Thereafter some airlines experimented with biofuels on commercial flights.<ref>{{cite news |url= https://www.nytimes.com/2011/10/10/business/global/10iht-green10.html?_r=1 |title= Airlines Weigh the Advantages of Biofuels |newspaper= NY Times |date= 9 Oct 2011 |author= Bettina Wassener}}</ref> As of July 2020, seven annexes to D7566 were published, including various biofuel types:<ref>{{cite news|url=https://www.greencarcongress.com/2020/05/20200514-ihi.html|title=ASTM approves 7th annex to D7566 sustainable jet fuel specification: HC-HEFA|date=May 14, 2020|journal=Green Car Congress|access-date=August 8, 2021}}</ref>
* Fischer-Tropsch Synthetic Paraffinic Kerosene (FT-SPK, 2009)
* Hydroprocessed Esters and Fatty Acids Synthetic Paraffinic Kerosene (HEFA-SPK, 2011)
* usHydroprocessed Fermented Sugars to Synthetic Isoparaffins (HFS-SIP, 2014)
* Fischer-Tropsch Synthetic Paraffinic Kerosene with Aromatics (FT-SPK/A, 2015)
* Alcohol to Jet Synthetic Paraffinic Kerosene (ATJ-SPK, 2016)
* Catalytic Hydrothermolysis Synthesized Kerosene (CH-SK, or CHJ; 2020).

In December 2011, the [[FAA]] awarded US$7.7 million to eight companies to develop [[Substitute good|drop-in]] sustainable fuels, especially from [[Alcohol (chemistry)|alcohol]]s, sugars, [[biomass]], and [[organic matter]] such as [[pyrolysis oil]]s, within its {{abbr|CAAFI|Commercial Aviation Alternative Fuel Initiative}} and {{abbr|CLEEN|Continuous Lower Emissions, Energy and Noise}} programs.<ref>{{cite news |url=http://www.renewableenergyworld.com/rea/news/article/2011/12/faa-awards-7-7-million-for-advancement-of-aviation-biofuels |title=FAA Awards $7.7 Million for Advancement of Aviation Biofuels |author=Meg Cichon |date=2 December 2011 |work=[[Renewable Energy World]] |access-date=6 December 2020 |archive-date=28 March 2014 |archive-url=https://web.archive.org/web/20140328195458/http://www.renewableenergyworld.com/rea/news/article/2011/12/faa-awards-7-7-million-for-advancement-of-aviation-biofuels |url-status=dead }}</ref>

Biofuel provider Solena filed for bankruptcy in 2015.<ref>{{Cite web|title=AirportWatch {{!}} Solena, the company meant to be producing jet fuel from London waste for BA, goes bankrupt|url=https://www.airportwatch.org.uk/2015/10/solena-the-company-meant-to-be-producing-jet-fuel-from-london-waste-for-ba-goes-bankrupt/|access-date=2021-08-30|website=www.airportwatch.org.uk}}</ref>

By 2015, cultivation of [[fatty acid methyl ester]]s and [[alkenone]]s from the algae, ''Isochrysis'', was under research.<ref>{{cite web|author1=Chris Reddy|author2=Greg O'Neil|title=Jet Fuel from Algae? Scientists probe fuel potential in common ocean plant |url= https://www.whoi.edu/oceanus/feature/jet-fuel-from-algae |date=28 January 2015 |work= Oceanus magazine |publisher= [[Woods Hole Oceanographic Institution]]}}</ref>

By 2016, Thomas Brueck of [[Technical University of Munich|Munich TU]] was forecasting that [[algaculture]] could provide 3–5% of jet fuel needs by 2050.<ref>{{cite news|title=From green slime to jet fuel: algae offers airlines a cleaner future |url= https://reuters.com/article/idUSKCN0Z117F |work= Reuters |date= 15 June 2016}}</ref>

In fall 2016, the [[International Civil Aviation Organization]] announced plans for multiple measures including the development and deployment of sustainable aviation fuels.<ref name=ICAOdec2018>{{Cite web |url= https://www.icao.int/environmental-protection/Documents/Sustainable%20Aviation%20Fuels%20Guide_100519.pdf |title= Sustainable Aviation Fuels Guide |publisher= ICAO |date= Dec 2018}}</ref>

Dozens of companies received hundreds of millions in [[venture capital]] from 2005 to 2012 to extract fuel oil from algae, some promising competitively-priced fuel by 2012 and production of {{convert|1|e9USgal|e6m3|abbr=unit}} by 2012-2014.<ref name=Greentech19april2017/> By 2017 most companies had disappeared or changed their [[business plan]]s to focus on other markets.<ref name=Greentech19april2017>{{cite web|last1=Wessof|first1=Eric|title=Hard Lessons From the Great Algae Biofuel Bubble|url=https://www.greentechmedia.com/articles/read/lessons-from-the-great-algae-biofuel-bubble#gs.5jG2khs|publisher=[[Greentech Media]]|date=19 April 2017}}</ref>

In 2019, 0.1% of fuel was SAF:<ref>{{Cite web|last=2021-03-25T14:13:00+00:00|title=How sustainable fuel will help power aviation's green revolution|url=https://www.flightglobal.com/flight-international/how-sustainable-fuel-will-help-power-aviations-green-revolution/143044.article|access-date=2021-03-28|website=Flight Global }}</ref> The [[International Air Transport Association]] (IATA) supported the adoption of Sustainable Aviation fuel, aiming in 2019 for 2% share by 2025: {{convert|7|e6m3|e9USgal|abbr=unit}}.<ref name=IATAmay2019>{{cite web |url= https://www.iata.org/contentassets/ed476ad1a80f4ec7949204e0d9e34a7f/fact-sheet-alternative-fuels.pdf |title= Sustainable Aviation Fuels Fact sheet |publisher= IATA |date= May 2019}}</ref><ref name=IEA18mar2019>{{cite news |url= https://www.iea.org/commentaries/are-aviation-biofuels-ready-for-take-off |title= Are aviation biofuels ready for take off? |author= Pharoah Le Feuvre |date= 18 March 2019 |publisher= [[International Energy Agency]]}}</ref>

[[File:United Airlines - N851UA -Airbus A319 - San Francisco International Airport-0383.jpg|thumb|In 2019, [[United Airlines]] purchased up to {{convert|10|e6USgal|m3}} of SAF from [[World Energy (company)|World Energy]] over two years.<ref>{{cite press release |url= https://hub.united.com/united-biofuel-commitment-world-energy-2635867299.html |title= Expanding our commitment to powering more flights with biofuel |publisher= United Airlines |date= May 22, 2019}}</ref>]]

By that year, [[Virgin Australia]] had fueled more than 700 flights and flown more than one million kilometers, domestic and international, using [[Gevo Inc|Gevo]]'s alcohol-to-jet fuel.<ref>{{Cite press release |url= https://newsroom.virginaustralia.com/release/virgin-australia%E2%80%99s-sustainable-aviation-fuel-flies-one-million-kilometres|title=Virgin Australia's sustainable aviation fuel flies one million kilometres |publisher= Virgin Australia |date=17 June 2019}}</ref> [[Virgin Atlantic]] was working to regularly use fuel derived from the waste gases of [[steel mill]]s, with [[New Zealand Superannuation Fund#LanzaTech|LanzaTech]].<ref name=AvWeek26apr2019/> [[British Airways]] wanted to convert household waste into jet fuel with [[Fischer–Tropsch process#Velocys|Velocys]].<ref name=AvWeek26apr2019/> [[United Airlines]] committed to {{convert|900|e6USgal|m3|abbr=unit}} of sustainable aviation fuel for 10 years from Fulcrum BioEnergy (of its {{convert|4.1|e9USgal|m3|abbr=unit}} fuel consumption in 2018), after a $30 million investment in 2015.<ref name=AvWeek26apr2019/>

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 to [[JetBlue Airways]] over 10 years.<ref name="AvWeek26apr2019" /> At its sites in [[Singapore]], [[Rotterdam]] and [[Porvoo]], Finland's [[Neste]] expected to improve its renewable fuel production capacity from {{convert|2.7 to 3.0|e6t|e9lb|abbr=unit}} a year by 2020, and to increase its Singapore capacity by {{convert|1.3|e6t|e9lb|abbr=unit}} to reach {{convert|4.5|e6t|e9lb|abbr=unit}} in 2022 by investing €1.4 billion ($1.6 billion).<ref name=AvWeek26apr2019>{{cite news |url= https://aviationweek.com/commercial-aviation/biofuel-market-nearing-tipping-point |title= Biofuel Market Is Nearing A Tipping Point |date= Apr 26, 2019 |author= Kerry Reals |work= Aviation Week & Space Technology}}</ref>

By 2020, [[International Airlines Group]] had invested $400 million to convert waste into sustainable aviation fuel with [[Fischer–Tropsch process#Velocys|Velocys]].<ref name=Flight3jan2020>{{cite news |url= https://www.flightglobal.com/ba-begins-offsetting-domestic-flight-emissions/135987.article |title= BA begins offsetting domestic flight emissions |date= 3 January 2020 |work= Flightglobal}}</ref>

In early 2021, Boeing's CEO [[Dave Calhoun]] said drop-in [[sustainable aviation fuel]]s are "the only answer between now and 2050" to reduce carbon emissions.<ref name=AvWeek4feb2021>{{cite news |url= https://aviationweek.com/aerospace/manufacturing-supply-chain/boeing-moves-forward-airbus-a321xlr-competitor-plan |title= Boeing Moves Forward With Airbus A321XLR-Competitor Plan |author= Guy Norris |date= February 4, 2021 |work= Aviation Week}}</ref> In May 2021, the [[International 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.<ref>{{Cite web |title=Net Zero Roadmaps |url=https://www.iata.org/en/programs/environment/roadmaps/ |access-date=2023-11-17 |website=www.iata.org |language=en}}</ref>

The 2022 [[Inflation 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."<ref>{{Cite web |date=November 16, 2023 |title=Fueling Aviation's Sustainable Transition (FAST) Grants |url=https://www.faa.gov/general/fueling-aviations-sustainable-transition-fast-grants |access-date=November 16, 2023 |website=Federal Aviation Administration}}</ref> In November, 2022, sustainable aviation fuels were a topic at [[2021 United Nations Climate Change Conference|COP26]].<ref>{{Cite web |last=Nations |first=United |title=COP26: Together for our planet |url=https://www.un.org/en/climatechange/cop26 |access-date=2023-11-17 |website=United Nations |language=en}}</ref>

As of 2023, 90% of biofuel was made from oilseed and sugarcane which are grown for this purpose only.<ref>{{Cite web |title=Biodiesel Market Size, Share & Trends Analysis Report, 2030 |url=https://www.grandviewresearch.com/industry-analysis/biodiesel-market |access-date=2023-11-17 |website=www.grandviewresearch.com |language=en}}</ref>

==Production==
[[Jet fuel]] is a mixture of various [[hydrocarbon]]s. The mixture is restricted by product requirements, for example, [[freezing point]] and [[smoke point]]. Jet fuels are sometimes classified as [[Kerosene jet fuel|kerosene]] or [[naphtha]]-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 is [[ASTM]] approved via two routes. ASTM has found it safe to blend in 50% SPK into regular jet fuels.<ref>{{Cite web|url=https://www.astm.org/d7566-11.html|title=Standard Specification for Aviation Turbine Fuel Containing Synthesized Hydrocarbons|website=www.astm.org}}</ref><ref name=ASTMsep2011/> Tests have been done with blending synthetic paraffinic kerosene (SPK) in considerably higher concentrations.<ref>{{Cite journal|url=https://repository.tudelft.nl/islandora/object/uuid%3Aca415372-6ac0-4e7a-ab66-6e6dbf564e22|title=Evaluation of safety, performance and emissions of synthetic fuel blends in a Cessna Citation II|first1=T. A.|last1=Snijders|first2=J. A.|last2=Melkert|date=December 22, 2011|journal=Conference Proceedings of the 3AF/AIAA Aircraft Noise and Emissions Reduction Symposium, 25–27 October 2011, Marseille, France|via=repository.tudelft.nl}}</ref>

; HEFA-SPK 
: Hydroprocessed Esters and Fatty Acids Synthetic Paraffinic Kerosine (HEFA-SPK) is a specific type of hydrotreated [[vegetable oil fuel]].<ref name="Doliente2020" /> {{As of|2020|}} this was the only [[mature technology]]<ref name="IEA18mar2019" /><ref name="Doliente2020" /><ref>{{cite journal |last1=Starck |first1=Laurie |last2=Pidol |first2=Ludivine |last3=Jeuland |first3=Nicolas |last4=Chapus |first4=Thierry |last5=Bogers |first5=Paul |last6=Bauldreay |first6=Joanna |title=Production of Hydroprocessed Esters and Fatty Acids (HEFA) – Optimisation of Process Yield |journal=Oil & Gas Science and Technology – Revue d'IFP Energies nouvelles |date=January 2016 |volume=71 |issue=1 |pages=10 |doi=10.2516/ogst/2014007 |s2cid=45086444 |url=https://ogst.ifpenergiesnouvelles.fr/articles/ogst/pdf/2016/01/ogst120241.pdf |access-date=3 November 2022 |language=en}}</ref> (but by 2024 FT-SPK was commercialized as well<ref>{{Cite web |title=The feedstocks of the future has landed |url=https://www.topsoe.com/saf-feedstocks |access-date=2024-10-15 |website=www.topsoe.com |language=en}}</ref>). HEFA-SPK was approved by [[Altair Engineering]] for use in 2011.<ref>{{cite web |title=Biofuel Factsheet - Aviation Biofuels |url=https://www.etipbioenergy.eu/images/ETIP_Bioenergy_Factsheet_Aviation_Biofuels.pdf |website=European Technology Innovation Platform - Bioenergy |access-date=3 November 2022 |archive-url=https://web.archive.org/web/20220629124155/https://www.etipbioenergy.eu/images/ETIP_Bioenergy_Factsheet_Aviation_Biofuels.pdf |archive-date=29 June 2022 |language=en |date=2017 |url-status=live}}</ref> HEFA-SPK is produced by the [[deoxygenation]] and hydroprocessing of the [[Raw material|feedstock]] [[fatty acid]]s of [[algae]], [[jatropha]], and [[camelina]].<ref>{{Cite web|url=https://aviationbenefits.org/environmental-efficiency/climate-action/sustainable-aviation-fuel/producing-sustainable-aviation-fuel/|title = Producing sustainable aviation fuel}}</ref>
; Bio-SPK 
: This fuel uses oil extracted from plant or animal sources such as [[Jatropha oil|''jatropha'']], [[algae]], [[tallows]], waste oils, [[Babassu oil|babassu]], and ''[[Camelina]]'' to produce synthetic paraffinic kerosene (bio-SPK) by cracking and [[hydroprocessing]]. Using [[algae]] to make jet fuel remains an [[emerging technology]]. Companies working on algae jet fuel include [[Solazyme]], Honeywell UOP, Solena, [[Sapphire Energy]], [[Imperium Renewables]], and Aquaflow Bionomic Corporation. Universities working on algae jet fuel are [[Arizona State University]] and [[Cranfield University]]. Major investors for algae-based SPK research are [[Boeing]], [[Honeywell]]/[[UOP LLC|UOP]], [[Air New Zealand]], [[Continental Airlines]], [[Japan Airlines]], and [[General Electric]].{{Citation needed|date=February 2023}}
; FT-SPK 
: Processing solid [[biomass]] using [[pyrolysis]] can produce [[pyrolysis oil|oil]] or [[gasification]] to produce a [[syngas]] that is processed into FT SPK ([[Fischer–Tropsch process|Fischer–Tropsch]] Synthetic Paraffinic Kerosene).{{Citation needed|date=February 2023}}
; ATJ-SPK 
: The alcohol-to-jet (ATJ) pathway takes alcohols such as [[ethanol]] or [[butanol]] and de-oxygenates and processes them into jet fuels.<ref>{{Cite web|url=https://advancedbiofuelsusa.info/tag/atj-spk-alcohol-to-jet-synthetic-paraffinic-kerosene/|title=Advanced BioFuels USA – Truly Sustainable Renewable Future|website=advancedbiofuelsusa.info}}</ref> Companies such as LanzaTech have created ATJ-SPK from {{chem2|CO2}} in [[flue gas]]es.<ref>{{Cite web|url=https://www.lanzatech.com/2018/04/03/jet-fuel-derived-ethanol-now-eligible-commercial-flights/|title=Jet Fuel Derived from Ethanol Now Eligible for Commercial Flights|access-date=2020-12-22|archive-date=2022-01-25|archive-url=https://web.archive.org/web/20220125161620/https://www.lanzatech.com/2018/04/03/jet-fuel-derived-ethanol-now-eligible-commercial-flights/|url-status=dead}}</ref> The ethanol is produced from CO in the flue gases using microbes such as ''[[Clostridium autoethanogenum]]''. In 2016 LanzaTech demonstrated its technology at Pilot scale in NZ – using Industrial waste gases from the steel industry as a feedstock.<ref>Voegele, E. November 2009. "Waste to ethanol projects move forward", Ethanol Producer Magazine</ref><ref>{{Cite web|url=https://www.triplepundit.com/story/2013/interview-lanzatech-ceo-jennifer-holmgren/52196|title=Interview: LanzaTech CEO Jennifer Holmgren|website=www.triplepundit.com}}</ref><ref>{{Cite journal|url= |title=Genome editing of Clostridium autoethanogenum using CRISPR/Cas9|first1=Shilpa|last1=Nagaraju|first2=Naomi Kathleen|last2=Davies|first3=David Jeffrey Fraser|last3=Walker|first4=Michael|last4=Köpke|first5=Séan Dennis|last5=Simpson|date=October 18, 2016|journal=Biotechnology for Biofuels|volume=9|issue=1|pages=219|doi=10.1186/s13068-016-0638-3|pmid=27777621|pmc=5069954 |doi-access=free |bibcode=2016BB......9..219N }}</ref> [[Gevo]] developed technology to retrofit existing [[ethanol]] plants to produce [[isobutanol]].<ref>{{Cite web |url=https://gevo.com/wp-content/uploads/2020/05/Gevo-Whitepaper-Sustainable-Aviation-Fuel.pdf |title=Archived copy |access-date=2021-11-23 |archive-date=2021-06-23 |archive-url=https://web.archive.org/web/20210623212715/https://gevo.com/wp-content/uploads/2020/05/Gevo-Whitepaper-Sustainable-Aviation-Fuel.pdf |url-status=dead }}</ref> Alcohol-to-Jet Synthetic Paraffinic Kerosene (ATJ-SPK) is a proven pathway to deliver bio-based, low-carbon fuel.{{Citation needed|date=February 2023}}

=== Future production routes ===
Systems that use [[synthetic biology]] to create hydro-carbons are under development:
* The SUN-to-LIQUID project is examining Fischer-Tropsch hydro-carbon fuels (solar kerosine) through the use of a [[Chemical reactor|solar reactor]].<ref>{{Cite web|url=https://solar-jet.aero/page/about-solar-jet/news-events.php|title=SOLAR-JET project terminated and succeeded by SUN-TO-LIQUID project|website=solar-jet.aero}}</ref><ref>{{Cite web|url=https://ec.europa.eu/commission/presscorner/home/en|title=Press corner|website=European Commission - European Commission}}</ref><ref>{{Cite web|url=https://www.sun-to-liquid.eu/|title=SUN to LIQUID project - SUN to LIQUID project|website=www.sun-to-liquid.eu}}</ref> 
* Alder Fuels is proposing to convert [[lignocellulosic biomass]] (a common type of waste from forestry and agriculture) into a hydrocarbon-rich "greencrude" via [[pyrolysis]] (see: [[pyrolysis oil]]). Greencrude can be turned into fuel in refineries like crude oil.<ref>{{Cite news |date=August 17, 2022 |title=Ways to make aviation fuel green |newspaper=The Economist |url=https://www.economist.com/science-and-technology/2022/08/17/ways-to-make-aviation-fuel-green |access-date=2023-02-23 |issn=0013-0613}}</ref>
* Universal Fuel Technologies is marketing its Flexiforming technology that can use different feedstocks and even the byproducts from existing renewable fuel manufacturing processes to produce SAF.<ref>{{Cite news |date=August 14, 2024 |title=New SAF Process Could Transform Industry |newspaper=Aviation Industry News |url=https://www.ainonline.com/aviation-news/aerospace/2024-08-14/new-saf-process-could-transform-industry}}</ref>

=== Piston engines ===
Small piston engines can be modified to burn [[ethanol]].<ref name="SDSU2016">{{cite web |url= http://www.age85.org/index.htm |archive-url= https://web.archive.org/web/20080515192245/http://www.age85.org/index.htm |url-status= dead |archive-date= 2008-05-15 |title= AGE-85 (Aviation Grade Ethanol) |publisher= South Dakota State University |year = 2006 }}</ref> [[Swift Fuel]], a biofuel alternative to [[avgas]], was approved as a test fuel by [[ASTM International]] in December 2009.<ref>{{cite press release |title=Indiana Airline Fuel Developer Moves Ahead With Testing |publisher=Purdue Research Park |date= December 14, 2009 |url= https://www.purdue.edu/uns/x/2009b/091214SwiftASTM.html }}</ref><ref>{{cite news |url= https://www.avweb.com/news/efforts-move-forward-to-produce-alternative-aviation-fuels/ |title= Efforts Move Forward To Produce Alternative Aviation Fuels |last= Grady |first= Mary |date= December 15, 2009}}</ref>

=== Technical challenges ===
[[Nitrile]]-based rubber materials expand in the presence of aromatic compounds found in conventional petroleum fuel. Pure biofuels that aren't mixed with petroleum and don't contain paraffin-based additives may cause rubber seals and hoses to shrink.<ref>{{cite web | title =Technical Report: Near-Term Feasibility of Alternative Jet Fuels | publisher =Sponsored by the FAA. Authored by MIT staff. Published by RAND Corporation| url =http://web.mit.edu/aeroastro/partner/reports/proj17/altfuelfeasrpt.pdf | access-date =August 22, 2012 }}</ref> Synthetic rubber substitutes that are not adversely affected by biofuels, such as [[Viton]], for seals and hoses are available.<ref>{{cite web | title =Biodiesel FAQ | publisher =[[University of Kentucky College of Agriculture, Food, and Environment]] | year =2006 | url =http://www.ca.uky.edu/agc/pubs/aen/aen90/aen90.pdf | access-date =August 22, 2012 }}</ref>

The [[United States Air Force]] found harmful bacteria and fungi in their biofueled aircraft, and use [[pasteurization]] to disinfect them.<ref>{{Cite web|url=https://www.af.mil/News/Article-Display/Article/939659/afrl-discovering-whats-bugging-military-aircraft/|title=AFRL discovering what's "bugging" military aircraft|website=U.S. Air Force|date=11 September 2016 }}</ref>

==Economics==
In 2019 the [[International 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.<ref name=IEA18mar2019/> By 2019, fossil jet fuel production cost was $0.3-0.6 per L given a $50–100 crude [[oil barrel]], while aviation biofuel production cost was $0.7-1.6, needing a $110–260 crude oil barrel to [[break-even]].<ref name=IEA18mar2019/>

{{As of|2020|}} aviation biofuel was more expensive than fossil jet kerosene,<ref name=IU4dec2020/> considering [[aviation taxation and subsidies]] at that time.<ref>{{Cite web |title= Sustainable Aviation Fuel: Review of Technical Pathways |url= https://www.energy.gov/sites/prod/files/2020/09/f78/beto-sust-aviation-fuel-sep-2020.pdf |date= Sep 2020 |publisher= [[United States Department of Energy]]}}</ref>

As of a 2021 analysis, VFA-SAF break-even cost was {{Convert|2.50|$/gal|$/l|abbr=on}}.<ref name="auto"/> This number was generated considering credits and incentives at the time, such as [[LCFS|California's LCFS]] (Low Carbon Fuel Standard) credits and the US Environmental Protection Agency (EPA) [[Renewable Fuel Standard (United States)|Renewable Fuel Standard]] incentives.

==Sustainable aviation fuels==
[[File:Oslo Airport terminal night view.jpg|thumb|In 2016, [[Oslo Airport]] became the first international airport to offer sustainable aviation fuel as part of the fuel mix.]]

[[Sustainable biofuel]]s do not use [[food crop]]s, prime [[agricultural land]] or fresh water. '''Sustainable aviation fuel''' (SAF) is certified by a third-party such as the [[Sustainable biofuel#Roundtable on Sustainable Biomaterials|Roundtable For Sustainable Biofuels]].<ref>{{cite news |url= http://aviationweek.com/commercial-aviation/glacial-pace-advancements-biofuel-threatens-emissions-targets |title= Glacial Pace Of Advancements In Biofuel Threatens Emissions Targets |date= Oct 10, 2017 |author= Kerry Reals |work=[[Aviation Week & Space Technology]]}}</ref>

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 or [[kerosene]].<ref name=Economist18aug2022>{{Cite news |title=Ways to make aviation fuel green |newspaper=The Economist |url=https://www.economist.com/science-and-technology/2022/08/17/ways-to-make-aviation-fuel-green |date=2022-08-17 |issn=0013-0613}}</ref>

===Certification===
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 the [[European Union Emissions Trading Scheme]] (EUTS), a certified SAF product may be exempted from carbon compliance liability costs.<ref>{{cite web|url=http://ec.europa.eu/energy/renewables/biofuels/sustainability_schemes_en.htm|title=Sustainability schemes for biofuels|work=European Commission/Energy/Renewable energy/Biofuels|access-date=1 April 2012}}</ref> This marginally improves SAF's economic competitiveness versus fossil-based fuel.<ref>{{cite web|url=http://www.qantas.com.au/travel/airlines/sustainable-aviation-fuel/global/en#jump4 |title=Sustainable Aviation Fuel |publisher=Qantas |access-date=2013-10-24}}</ref>

The first reputable body to launch a sustainable biofuel certification system was the European-based Roundtable on Sustainable Biomaterials (RSB) NGO.<ref>{{cite web |url=http://rsb.epfl.ch/files/content/sites/rsb2/files/Biofuels/Documents%20and%20Resources/11-10-07_RSB_Fact_Sheet_EN.pdf |title=RSB Roundtable on Sustainable Biomaterials &#124; Roundtable on Sustainable Biomaterials |website=Rsb.epfl.ch |date=2013-10-17 |access-date=2013-10-24 |archive-date=2011-12-22 |archive-url=https://web.archive.org/web/20111222050201/http://rsb.epfl.ch/files/content/sites/rsb2/files/Biofuels/Documents%20and%20Resources/11-10-07_RSB_Fact_Sheet_EN.pdf |url-status=dead }}</ref> Leading airlines and other signatories to the Sustainable Aviation Fuel Users Group (SAFUG) pledged to support RSB as their preferred certification provider.<ref>{{cite web|url=http://www.safug.org/information/pledge/ |access-date=March 29, 2012 |url-status=dead |archive-url=https://web.archive.org/web/20120425051329/http://www.safug.org/information/pledge/ |archive-date=April 25, 2012 |title=Our Commitment to Sustainable Options}}</ref><ref>{{cite web|url=http://www.safug.org/ |title=Sustainable Aviation Fuel Users Group – SAFUG |website=Safug.org |access-date=2013-10-24}}</ref>

Some SAF pathways procured [[Renewable Identification Number|RIN]] pathways under the United States's [[Renewable Fuel Standard (United States)|renewable fuel standard]] which can serve as an implicit certification if the RIN is a [[Renewable Identification Number|Q-RIN]].

====Criteria====
{{More footnotes needed|section|date=February 2023}}
; EU RED II Recast (2018) 
: Greenhouse gas emissions from sustainable fuels must be lower than those from the fuels they replace: at least 50% for production built before 5 October 2015, 60% after that date and 65% after 2021. Raw materials cannot be sourced from land with high biodiversity or high carbon stocks (i.e. primary and protected forests, biodiversity-rich grasslands, wetlands and [[peatland]]s). Other sustainability issues are set out in the Governance Regulation and may be covered voluntarily.

; ICAO 'CORSIA'
: GHG Reduction - Criterion 1: lifecycle reductions of at least 10% compared to fossil fuel. Carbon Stock - Criterion 1: not produced from biomass obtained from land whose uses changed after 1 January 2008 from primeval forests, wetlands or peatlands, as all these lands have high carbon stocks. Criterion 2: For [[land use change]]s after 1 January 2008, (using IPCC land categories), if emissions from direct land use change (DLUC) exceed the default value of the induced land use change (ILUC), the value of the DLUC replaces the default (ILUC) value.

===Global impact===
As [[emissions 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<ref>{{cite web |title=Revision of the EU Energy Tax Directive - technical press briefing |url=http://ec.europa.eu/taxation_customs/resources/documents/taxation/review_of_regulation_en.pdf |access-date=2013-10-24 |website=Ec.europa.eu}}</ref> that only fuels certified as sustainable by the RSB or similar body would be zero-rated.<ref>{{cite web|url=http://www.safug.org/assets/docs/SAFUG_Brochure.pdf |title=Sustainable Aviation Fuel Users Group : European Section |website=Safug.org |access-date=2013-10-24}}</ref> SAFUG was formed by a group of interested airlines in 2008 under the auspices of [[Boeing Commercial Airplanes]]. Member airlines represented more than 15% of the industry, and signed a pledge to work towards SAF.<ref>{{cite web|url=http://www.boeing.com/newairplane/environment/#/SustainableAviationBiofuel/UsersGroup |title=Environment and Biofuels &#124; Boeing Commercial Airplanes |website=Boeing.com |access-date=2013-10-24}}</ref><ref>{{cite web|url=http://www.safug.org/safug-pledge/ |title= SAFUG Pledge; Boeing Commercial Airplanes |website=Safug.org |access-date=2015-07-10}}</ref>

In addition to SAF certification, the integrity of aviation biofuel producers and their products could be assessed by means such as [[Richard Branson]]'s Carbon War Room,<ref>{{cite web |url=http://www.carbonwarroom.com/sectors/transport/aviation/operation-renewablejetfuels#mission |title=Renewable Jet Fuels |publisher=Carbon War Room |access-date=2013-10-24 |archive-date=2013-10-30 |archive-url=https://web.archive.org/web/20131030013036/http://www.carbonwarroom.com/sectors/transport/aviation/operation-renewablejetfuels#mission |url-status=dead }}</ref> or the Renewable Jet Fuels initiative.<ref>{{cite web |url=http://renewablejetfuels.org/ |title=Welcome |publisher=Renewable Jet Fuels |access-date=2013-10-24 |archive-date=2013-10-29 |archive-url=https://web.archive.org/web/20131029205231/http://renewablejetfuels.org/ |url-status=dead }}</ref> The latter works with companies such as LanzaTech, SG Biofuels, AltAir, Solazyme, and Sapphire.<ref>{{cite web|url=http://www.sustainablesky.com |title=Sustainable Sky Institute |publisher=Sustainable Sky Institute |access-date=2016-04-26}}</ref>{{verify source|date=February 2023}}

Along with her co-authors, [[Candelaria Bergero]] of the [[University of California]]'s [[Earth System Science]] Department stated that "main challenges to scaling up such sustainable fuel production include technology costs and process efficiencies", and widespread production would undermine [[food security]] and [[land use]].<ref>{{cite journal |last1=Bergero |first1=Candelaria |display-authors= etal |title=Pathways to net-zero emissions from aviation |journal= [[Nature Sustainability]] |date=30 January 2023 |volume=6 |issue=4 |pages=404–414 |doi=10.1038/s41893-022-01046-9 |s2cid=256449498 |doi-access=free |bibcode=2023NatSu...6..404B |url=https://www.researchsquare.com/article/rs-1871023/latest.pdf }}</ref>

=== Certified processes ===
{| class="wikitable"
|-
! 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)]], [[Total S.A.]]
|-
| 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
|}

== See also ==
* [[Biodiesel]]
* [[Fossil fuel phase-out]]
* [[List of emerging technologies]]
* [[Vegetable oil fuel]]

==References==
{{Reflist}}

==Further reading==

* {{cite news |url= http://aviationweek.com/technology/opinion-biofuels-sustainable-essential-aviation-s-future |title= Opinion: Biofuels Sustainable, Essential To Aviation's Future |date= Oct 23, 2017 |author=Adam Klauber ([[Rocky Mountain Institute]]) |author2=Isaac Toussie (Rocky Mountain Institute) |author3=Steve Csonka (Commercial Aviation Alternative Fuels Initiative) |author4=Barbara Bramble ([[National Wildlife Federation]]) |work=Aviation Week & Space Technology}}
* {{cite web |url= https://aim-builds.s3.amazonaws.com/gevo/Gevo+WP_aviation+fuel.pdf  |title= Sustainable Aviation Fuel |quote= Alcohol-to-Jet Synthetic Paraffinic Kerosene Is a Proven Pathway to Deliver a Bio-Based, Low-Carbon Option to Travelers |publisher= [[Gevo]] |date= December 2019 }}
* {{cite report |url= https://www3.weforum.org/docs/WEF_Clean_Skies_Tomorrow_SAF_Analytics_2020.pdf |title= Clean Skies for Tomorrow |quote= Sustainable Aviation Fuels as a Pathway to Net-Zero Aviation |date= Nov 2020 |publisher= World Economic Forum |author= McKinsey & Company}}

==External links==
* {{cite web |url= https://www.sustainablesky.com/  |title= Sustainable Sky Institute |quote= non-profit think tank/do tank focused on [...] the market transformation of the world's air transport system towards a [...] sustainable long-term future}}
* {{cite web |url= https://aviationbenefits.org/environmental-efficiency/climate-action |publisher= [[Air Transport Action Group]] |work= Aviation: Benefits Beyond Borders |title= Aviation industry reducing its environmental footprint}}
* {{cite web  |url= http://www.cleancluster.dk/NISA  |title= Nordic Initiative for Sustainable Aviation  |quote= Nordic association working to promote and develop a more sustainable aviation industry, with a specific focus on alternative sustainable fuels  |access-date= 2015-03-27  |archive-date= 2015-04-02  |archive-url= https://web.archive.org/web/20150402212013/http://cleancluster.dk/NISA  |url-status= dead  }}
* {{cite web |url= https://rsb.org/ |title= Roundtable on Sustainable Biofuels |quote= The RSB is supporting the development of a sustainable bioeconomy}}
* {{cite web |url= http://www.inderscience.com/jhome.php?jcode=ijsa  |title= International Journal of Sustainable Aviation |publisher= [[Inderscience Publishers]]}}
* {{cite web |url= https://ec.europa.eu/energy/topics/renewable-energy/biofuels/biofuels-aviation_en |title= Biofuels for aviation |date= 5 September 2023 |publisher= European Commission}}
* {{cite news |url= https://www.flightglobal.com/flight-international-opinion/why-industry-needs-global-standards-for-sustainable-fuel-use/143384.article |title= Why industry needs global standards for sustainable fuel use |date= 22 April 2021 |author= Geoff Hunt |work= Flightglobal}}

[[Category:Algae fuel]]
[[Category:Aviation and the environment]]
[[Category:Aviation fuels]]
[[Category:Biofuels]]