Aviation biofuel is a biofuel used for aircraft. Aviation biofuel is widely considered by the aviation industry to be one of the primary means by which the industry can reduce its carbon footprint. After a multi-year technical review from aircraft makers, engine manufacturers and oil companies, biofuels were approved for commercial use in July 2011. Since then, some airlines have experimented with using of biofuels on commercial flights. The focus of the industry is on second generation sustainable biofuels that do not compete with food.
Rationale for aviation biofuels 
Aviation's share of the greenhouse gas emissions is poised to grow, as air travel increases and ground vehicles use more alternative fuels like ethanol and biodiesel. Currently aviation represents 2% of global emissions, but is expected to grow to 3% by 2050. In addition to building more fuel efficient aircraft and operating them more efficiently, changing the fuel source is one of the few options the aviation industry has for reducing its carbon footprint. While solar, electric and hydrogen propelled aircraft are being researched, it is not expected they will be feasible in the near or medium term due to aviation's need for high power-to-weight ratio and globally compatible infrastructure.
Concerns and challenges 
Biodiesel that is stored for long periods of time is more likely to oxidize, especially at low temperatures, causing it to gel. Some additives improve the cold weather tolerance of biodiesel, but only by a few degrees. Nitrile-based rubber materials expand in the presence of aromatic compounds found in conventional petroleum fuel. Pure biofuels that aren't mixed with petrolum and don't contain paraffin-based additives may cause rubber seals and hoses to shrink. Manufacturers are starting to use a synthetic rubber substitute called Viton for seals and hoses. Viton isn't adversely affected by biofuels.
Industry commitments and collaborations 
The International Air Transport Association (IATA) supports research, development and deployment of alternative fuels. IATA thinks a 6% share of sustainable 2nd generation biofuels is achievable by 2020, and Boeing supports a target of 1% of global aviation fuels by 2015. This is in support of the goals of the aviation industry reaching carbon neutral growth by 2020 and a 50% decrease in carbon emissions by 2050 (relative to a 2005 baseline)
A group of interested airlines has formed the Sustainable Aviation Fuel Users Group (SAFUG). The group was formed in 2008 in cooperation with support from NGOs such as Natural Resources Defense Council and The Roundtable For Sustainable Biofuels (RSB). Member airlines represent more than 15% of the industry, and all member CEOs have signed a pledge to work on the development and use of sustainable biofuels for aviation.
Production routes and sources 
Jet fuel is a mixture of a large number of different hydrocarbons. The range of their sizes (molecular weights or carbon numbers) is restricted by the requirements for the product, for example, freezing point or smoke point. Jet fuels are sometimes classified as 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 completely interchangeable with conventional fuels. Deriving "drop-in" jet fuel from bio-based sources is ASTM approved via two routes.
The first route involves using oil which is extracted from plant sources like jatropha, algae, tallows, other waste oils, Babassu and camelina to produce bio-SPK (Bio derived synthetic paraffinic Kerosene) by cracking and hydroprocessing.
The growing of algae to make jet fuel is a promising but still emerging technology. Companies working on algae jet fuel are 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
The second route involves processing solid biomass using pyrolysis to produce pyrolysis oil or gassification to produce a syngas which is then processed into FT SPK (Fischer–Tropsch Synthetic Paraffinic Kerosene).
Future production routes 
Further research is being done on an alcohol-to-jet pathway where alcohols such as ethanol or butanol are de-oxygenated and processed into jet fuels. In addition, routes that use synthetic biology to directly create hydro-carbons are being researched.
Commercial and demonstration flights 
Since 2008, a large number of test flights have been conducted, and since ASTM approval in July 2011, several commercial flights with passengers have also occurred.
Demonstration flights 
|Feb 2008||Virgin Atlantic||Boeing 747||Coconut and Babassu||Virgin flew the very first biofuel test flight between London and Amsterdam, using a 20% blend of biofuels in one of its engines|
|Dec 2008||Air New Zealand||Boeing 747||Jatropha||A two-hour test flight using a 50-50 mixture of the new biofuel with Jet A-1 in the number one position Rolls Royce RB-211 engine of 747-400 ZK-NBS, was successfully completed on 30 December 2008. The engine was then removed to be scrutinised and studied to identify any differences between the Jatropha blend and regular Jet A1. No effects to performances were found.|
|Jan 2009||Continental Airlines||Boeing 737||Algae and jatropha||Continental Airlines ran the first flight of an algae-fueled jet. The flight from Houston's George Bush Intercontinental Airport completed a circuit over the Gulf of Mexico. The pilots on board executed a series of tests at 38,000 feet (12,000 m), including a mid-flight engine shutdown. Larry Kellner, chief executive of Continental Airlines, said they had tested a drop-in fuel which meant that no modification to the engine was required. The fuel was praised for having a low flash point and sufficiently low freezing point, issues that have been problematic for other bio-fuels.|
|Jan 2009||Japan Airlines||Boeing 747||Camelina, jatropha and algae||Japan Airlines conducted a one and a half hour flight with one engine burning a 50/50 mix of Jet-A and biofuel from the Camelina plant.|
|Apr 2010||US Navy||F/A-18||Camelina||The Navy tested this biofuel blend on the F⁄A-18 Super Hornet aka "Green Hornet". Results from those tests indicated the aircraft performed as expected through its full flight envelope with no degradation of capability.|
|Mar 2010||US Air Force||A-10||Waste cooking oil||On March 25, 2010, the United States Air Force conducted the first flight of an aircraft with all engines powered by a biofuel blend. The flight, performed on an A-10 at Eglin Air Force Base, used a 50/50 blend of JP-8 and Camelina-based fuel.|
|Jun 2010||Dutch Military||Ah-64 Apache Helicopter||Waste cooking oil|
|Jun 2010||EADS||Diamond D42||Algae||Occurred at an air show in Berlin in June 2010.|
|Nov 2010||US Navy||MH-60S Seahawk||Camelina||Flown on 50⁄50 biofuel blend Nov. 18, 2010 in Patuxent River, Md. The helicopter, from Air Test and Evaluation Squadron 21 at Naval Air Station Patuxent River tested a fuel mixture made from the Camelina seed.|
|Nov 2010||TAM||Airbus 320||Jatropha||A 50⁄50 biofuel blend of conventional and jatropha oil|
|Jun 2011||Boeing||Boeing 747-8F||Camelina||Boeing flew its new model 747-8F to the Paris Air Show with all four engines burning a 15% mix of biofuel from camelina|
|June 2011||Honeywell||Gulfstream G450||Camelina||The first transatlantic biofuels flight using a 50/50 blend of camelina-based biofuel and petroleum-based fuel.|
|Aug 2011||US Navy||T-45||Camelina||successfully flew a T-45 training aircraft using biofuels at the Naval Air Station (NAS) in Patuxent River, Maryland. The flight was completed by the “Salty Dogs” of Air Test and Evaluation Squadron 23 flying on biofuel mixture of 50/50 petroleum-based JP-5 jet fuel and plant-based camelina.|
|Sep 2011||US Navy||AV-8B||Camelina||Naval Air Warfare Center Weapons Division, China Lake performed the first bio-fuel flight test in AV-8B Harrier from Air Test and Evaluation Squadron 31.|
|Oct 2011||Air China||Boeing 747-400||Jatropha||Air China flew China's first flight using aviation biofuels. The flight was conducted using Chinese grown jatropha oil from PetroChina. The flight was 2 hours in duration above Beijing, and used 50% biofuel in 1 engine.|
|November 2011||Continental Airlines||Boeing 737-800||Algae||United / Continental flew a biofuel flight from IAH to ORD on algae jet fuel supplied by Solazyme. The fuel was partially derived from genetically modified algae that feed on plant waste and produce oil. It was the first biofuel-powered air service in the US.|
|November 2011||Alaska Airlines||Boeing 737 and Bombardier Q400||Algae||Alaska Airlines and its sister carrier, Horizon Air, converted 75 flights on their schedules to run on a fuel mixture of 80% kerosene and 20% biofuel derived from used cooking oil. The biofuel was made by Dynamic Fuels, a joint venture of Tyson Foods and Syntroleum Corp.|
|Jan 2012||Etihad Airways||Boeing 777-300ER||vegetable cooking oil||Etihad Airways conducted a biofuel flight from Abu Dhabi to Seattle using a combination of traditional jet fuel and fuel based on recycled vegetable cooking oil|
|October 2012||NRC||Dassault Falcon 20||Carinata||First jet to fly on 100% biofuels that meet petroleum specifications without blending. Fuel was produced by Applied Research Associates (ARA) and Chevron Lummus Global (CLG) from carinata oil supplied by Agrisoma Biosciences.|
|March 2013||Paramus Flying Club||Cessna 182||Waste cooking oil||First piston engine aircraft to fly with a 50/50 blend of aviation biofuel and conventional Jet-A (as specified by ASTM D7566). First piston engine aircraft to fly with a biofuel blend operating under a standard (not experimental) airworthiness certificate. Demonstration flight from North Central State Airport (KSFZ) in Rhode Island to First Flight Airport (KFFA) in North Carolina took place on March 2, 2013. The Cessna 182 had been converted under STC to be powered by an SMA jet-fuel diesel cycle piston engine, and the blended biofuel was provided by SkyNRG of Holland.|
Commercial flights 
|Jun 2011||KLM||Boeing 737-800||Used cooking oil||KLM flew the world's first commercial biofuel flight, carrying 171 passengers from Amsterdam to Paris|
|Jul 2011||Lufthansa||Airbus A321||Jatropha, camelina plants and animal fats||First German commercial biofuel's flight, and the start of 6 month regular series of flights from Hamburg to Frankfurt with one of the two engines use biofuel. It officially end at January 12, 2012 with a flight from Frankfurt to Washington and would not take biofuel further unless the biofuel was more widely produced.|
|Jul 2011||Finnair||Airbus A319||Used cooking oil||The 1,500 km journey between Amsterdam and Helsinki was fuelled with a mix of 50 per cent biofuel derived from used cooking oil and 50 per cent conventional jet fuel. Finnair says it will conduct at least three weekly Amsterdam-to-Helsinki flights using the biofuel blend in both of the aircraft's engines. Refueling will be done at Amsterdam Airport Schiphol.|
|Jul 2011||Interjet||Airbus A320||Jatropha||Flight was powered by 27% jatropha between Mexico City and Tuxtla Gutierrez|
|Aug 2011||AeroMexico||Boeing 777-200||Jatropha||Aeromexico flew the world's first trans-Atlantic revenue flight, from Mexico City to Madrid with passengers|
|Oct 2011||Thomson Airways||Boeing 757-200||Used cooking oil||Thomson flew the UK's first commercial biofuel flight from Birmingham Airport on one engine using biofuel from used cooking oil, supplied by SkyNRG|
|November 2011||Continental Airlines||Boeing 737-800||Algae||United / Continental flew biofuel flight from IAH to ORD on algae jet fuel, which supplied by Solazyme|
Environmental effects 
A life cycle assessment by the Yale School of Forestry on jatropha, one source of potential biofuels, estimated using it 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 to use. In addition, biofuels do not contain sulfur compounds and thus do not emit sulfur dioxide.
Many different standards exist for certification of sustainable biofuels. One such standard often cited by airlines is the one developed by the The Roundtable For Sustainable Biofuels. Nearly all such standards include a minimum amount of greenhouse gas reduction and consideration that biofuels do not compete with food.
See also 
- 'ASTM approval of biofuels'
- Airlines Weigh the Advantages of Biofuels
- 'IPCC Special Report on Aviation Global Emissions'
- "Renewable and Alternative Energy Fact Sheet". Agricultural Research and Cooperative Extension. Penn State College of Agricultural Science. Retrieved March 7, 2012.
- "Technical Report: Near-Term Feasibility of Alternative Jet Fuels". Sponsored by the FAA. Authored by MIT staff. Published by RAND Corporation. Retrieved August 22, 2012.
- "Biodiesel FAQ". University of Kentucky College of Agriculture. 2006. Retrieved August 22, 2012.
- 'IATA Fact Sheet: Alternative Fuels'
- 'Boeing targets 1% of aviation fuel'
- 'IATA Emission Targets'
- 'SAFUG Pledge'
- First Airlines and UOP Join Algal Biomass Organization, Green Car Congress, 19 June 2008.
- Dunn, Graham (24 February 2008). "Partners carry out first biofuel flight using Virgin 747". Flight International. Retrieved 25 August 2012.
- 'Virgin flight for biofuels'
- 'Air New Zealand Demonstration Flight'
- Lane, Jim (2009-01-08). "Continental Airlines tests aviation biofuel; first use of algae; first US biofuel test flight; first two-engine flight". Biofuels Digest. Retrieved 2009-09-20.
- "First flight of algae-fuelled jet". BBC. 2009-01-08.
- Morris, John (2010-06-07). "EADS Sets First Public Algae-Biofuel Flight At ILA Berlin". Aviation Week. Retrieved 2010-07-12.
- 'Test flight for TAM'
- 'Boeing 747-8F flies to Paris on biofuel'
- Cattermole, Tannith (June 26, 2011). "Gulfstream G450 crosses the Atlantic on 50/50 biofuel-jetfuel blend". GizMag. Retrieved March 7, 2012.
- Paur, Jason (June 17, 2011). "Trans-Atlantic Biofuel Flights Kick Off Paris Air Show". WIRED. Retrieved March 7, 2012.
- http://www.chinadaily.com.cn/bizchina/2011-10/29/content_14000985.htm 'China's first biofuels flight'
- Hilkevitch, Jon (November 11, 2011). "Continental Airlines flight is first in U.S. to use biofuel". LA Times. Retrieved April 16, 2012.
- "Alaska Airlines Launching Biofuel-Powered Commercial Service In The United States" (Press release). Alaska Airlines. November 7, 2011. Retrieved December 30, 2011.
- "NRC Flies World's First Civil Jet Powered by 100 Percent Biofuel". Aero-news Network. 7 November 2012. Retrieved 21 November 2012.
- 'First commercial biofuel flight'
- 'Lufthansa kicks off regular biofuel flight'
- "Lufthansa Wraps up Biofuel Test on German Flights". January 12, 2012.
- 'First biofuel flight in Latin-America'
- 'First Trans-Continental biofuel flight'
- 'First UK commercial flight'
- Hilkevitch, Jon (2011-11-11). "Continental Airlines flight is first in U.S. to use biofuel". Los Angeles Times.
- Bailis, R. E.; Baka, J. E. (2010). "Greenhouse Gas Emissions and Land Use Change fromJatropha Curcas-Based Jet Fuel in Brazil". Environmental Science & Technology 44 (22): 8684. doi:10.1021/es1019178.
Further reading 
- "Beginner’s Guide to Aviation Biofuels". Air Transport Action Group. May 2009. Retrieved 2011-11-20.
- Sustainable Aviation Fuels Pacific Northwest regional roadmap
- "Sustainable Aviation Fuels regional roadmap for Australia". June 2011.
- Airbus - Alternative fuels
- Boeing - 2010 Environment report Sustainable Biofuels
- International Air Transport Association - Fact Sheet: Alternative Fuels
- www.enviro.aero (Air Transport Action Group) - Sustainable biofuels
- Air travel, climate change, and green consumerism
- Aviation Environment Federation - Biofuel