An aviation biofuel (also known as bio-jet fuel [1] , sustainable aviation fuel (SAF) or bio-aviation fuel (BAF) [2] ) is a biofuel used to power aircraft. The International Air Transport Association (IATA) considers it a key element in reducing the environmental impact of aviation. [3] Aviation biofuel is used to 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.
Biofuels are biomass-derived fuels from plants, animals, or waste; depending on which type of biomass is used, they could lower CO2 emissions by 20–98% compared to conventional 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]
Aviation biofuel can be produced from plant or animal sources such as Jatropha , algae, tallows, waste oils, palm oil, Babassu, and Camelina (bio-SPK); from solid biomass using pyrolysis processed with a Fischer–Tropsch process (FT-SPK); with an alcohol-to-jet (ATJ) process from waste fermentation; or from synthetic biology through a solar reactor. Small piston engines can be modified to burn ethanol.
Sustainable biofuels are an alternative to electrofuels. [6] Sustainable aviation fuel is certified as being sustainable by a third-party organisation.
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 e-fuels technology, which combines waste CO2 with 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 woody biomass and agricultural and municipal waste, aiming to produce lower-carbon jet fuel more sustainably and efficiently. [7] [8]
Plants absorb carbon dioxide as they grow, therefore plant-based biofuels emit only the same amount of greenhouse 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 from non-food crops and forest residues (91–95% savings). [2]
Jatropha oil, a non-food oil used as a biofuel, lowers CO2 emissions by 50–80% compared to Jet-A1, a kerosene-based fuel. [9] Jatropha, used for biodiesel, can thrive on marginal land where most plants produce low yields. [10] [11] 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. [12]
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. [2] Neste Corporation's renewable products include a refining residue of food-grade palm oil, the oily waste skimmed from the palm oil mill's wastewater. Other Neste sources are used cooking oil from deep fryers and animal fats. [13] Neste's sustainable aviation fuel is used by Lufthansa; [14] Air France and KLM announced 2030 SAF targets in 2022 [15] including multi-year purchase contracts totaling over 2.4 million tonnes of SAF from Neste, TotalEnergies, and DG Fuels. [16]
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. [17] This lessens the need to grow crops specifically for fuel, which in itself is energy intensive and increases 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. [17] 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%. [18] Biofuels do not contain sulfur compounds and thus do not emit sulfur dioxide.[ citation needed ]
This section needs to be updated. The reason given is: Lots of plans announced years ago. No info on whether the plans were carried out..(March 2024) |
The first flight using blended biofuel took place in 2008. [19] Virgin Atlantic used it fly a commercial airliner, using feedstocks such as algae. [20] 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 The Roundtable For Sustainable Biofuels by 2008. They pledged to develop sustainable biofuels for aviation. [21] That year, Boeing was co-chair of the Algal Biomass Organization, joined by air carriers and biofuel technology developer UOP LLC (Honeywell). [22]
In 2009, the IATA committed to achieving carbon-neutral growth by 2020, and to halve carbon emissions by 2050. [23]
In 2010, Boeing announced a target 1% of global aviation fuels by 2015. [24]
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. [25] The safety and performance of jet fuel used in passenger flights is certified by ASTM International. [26] Biofuels were approved for commercial use after a multi-year technical review from aircraft makers, engine manufacturers and oil companies. [27] Thereafter some airlines experimented with biofuels on commercial flights. [28] As of July 2020, seven annexes to D7566 were published, including various biofuel types: [29]
In December 2011, the FAA awarded US$7.7 million to eight companies to develop drop-in sustainable fuels, especially from alcohols, sugars, biomass, and organic matter such as pyrolysis oils, within its CAAFI and CLEEN programs. [30]
Biofuel provider Solena filed for bankruptcy in 2015. [31]
By 2015, cultivation of fatty acid methyl esters and alkenones from the algae, Isochrysis, was under research. [32]
By 2016, Thomas Brueck of Munich TU was forecasting that algaculture could provide 3–5% of jet fuel needs by 2050. [33]
In fall 2016, the International Civil Aviation Organization announced plans for multiple measures including the development and deployment of sustainable aviation fuels. [34]
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 1 billion US gal (3.8 million m3) by 2012-2014. [35] By 2017 most companies had disappeared or changed their business plans to focus on other markets. [35]
In 2019, 0.1% of fuel was SAF: [36] The International 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). [37] [19]
By that year, Virgin Australia had fueled more than 700 flights and flown more than one million kilometers, domestic and international, using Gevo's alcohol-to-jet fuel. [39] Virgin Atlantic was working to regularly use fuel derived from the waste gases of steel mills, with LanzaTech. [40] British Airways wanted to convert household waste into jet fuel with Velocys. [40] 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. [40]
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. [40] At its sites in Singapore, Rotterdam and Porvoo, Finland's Neste 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). [40]
By 2020, International Airlines Group had invested $400 million to convert waste into sustainable aviation fuel with Velocys. [41]
In early 2021, Boeing's CEO Dave Calhoun said drop-in sustainable aviation fuels are "the only answer between now and 2050" to reduce carbon emissions. [42] 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. [43]
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." [44] In November, 2022, sustainable aviation fuels were a topic at COP26. [45]
As of 2023, 90% of biofuel was made from oilseed and sugarcane which are grown for this purpose only. [46]
Jet fuel is a mixture of various hydrocarbons. The mixture is restricted by product requirements, for example, freezing point and 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 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. [47] [26] Tests have been done with blending synthetic paraffinic kerosene (SPK) in considerably higher concentrations. [48]
Systems that use synthetic biology to create hydro-carbons are under development:
Small piston engines can be modified to burn ethanol. [64] Swift Fuel, a biofuel alternative to avgas, was approved as a test fuel by ASTM International in December 2009. [65] [66]
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. [67] Synthetic rubber substitutes that are not adversely affected by biofuels, such as Viton, for seals and hoses are available. [68]
The United States Air Force found harmful bacteria and fungi in their biofueled aircraft, and use pasteurization to disinfect them. [69]
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. [19] 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. [19]
As of 2020 [update] aviation biofuel was more expensive than fossil jet kerosene, [1] considering aviation taxation and subsidies at that time. [70]
As of a 2021 analysis, VFA-SAF break-even cost was $2.50/US gal ($0.66/L). [17] This number was generated considering credits and incentives at the time, such as California's LCFS (Low Carbon Fuel Standard) credits and the US Environmental Protection Agency (EPA) Renewable Fuel Standard incentives.
Sustainable biofuels do not use food crops, prime agricultural land or fresh water. Sustainable aviation fuel (SAF) is certified by a third-party such as the Roundtable For Sustainable Biofuels. [71]
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. [72]
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. [73] This marginally improves SAF's economic competitiveness versus fossil-based fuel. [74]
The first reputable body to launch a sustainable biofuel certification system was the European-based Roundtable on Sustainable Biomaterials (RSB) NGO. [75] Leading airlines and other signatories to the Sustainable Aviation Fuel Users Group (SAFUG) pledged to support RSB as their preferred certification provider. [76] [77]
Some SAF pathways procured RIN pathways under the United States's renewable fuel standard which can serve as an implicit certification if the RIN is a Q-RIN.
This section includes a list of general references, but it lacks sufficient corresponding inline citations .(February 2023) |
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 [78] that only fuels certified as sustainable by the RSB or similar body would be zero-rated. [79] 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. [80] [81]
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, [82] or the Renewable Jet Fuels initiative. [83] The latter works with companies such as LanzaTech, SG Biofuels, AltAir, Solazyme, and Sapphire. [84] [ verification needed ]
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. [85]
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 |
Biofuel is a fuel that is produced over a short time span from biomass, rather than by the very slow natural processes involved in the formation of fossil fuels such as oil. Biofuel can be produced from plants or from agricultural, domestic or industrial biowaste. Biofuels are mostly used for transportation, but can also be used for heating and electricity. Biofuels are regarded as a renewable energy source. The use of biofuel has been subject to criticism regarding the "food vs fuel" debate, varied assessments of their sustainability, and ongoing deforestation and biodiversity loss as a result of biofuel production.
Biodiesel is a renewable biofuel, a form of diesel fuel, derived from biological sources like vegetable oils, animal fats, or recycled greases, and consisting of long-chain fatty acid esters. It is typically made from fats.
Aviation fuels are petroleum-based fuels, or petroleum and synthetic fuel blends, used to power aircraft. They have more stringent requirements than fuels used for ground use, such as heating and road transport, and contain additives to enhance or maintain properties important to fuel performance or handling. They are kerosene-based for gas turbine-powered aircraft. Piston-engined aircraft use leaded gasoline and those with diesel engines may use jet fuel (kerosene). By 2012, all aircraft operated by the U.S. Air Force had been certified to use a 50-50 blend of kerosene and synthetic fuel derived from coal or natural gas as a way of stabilizing the cost of fuel.
Jet fuel or aviation turbine fuel is a type of aviation fuel designed for use in aircraft powered by gas-turbine engines. It is colorless to straw-colored in appearance. The most commonly used fuels for commercial aviation are Jet A and Jet A-1, which are produced to a standardized international specification. The only other jet fuel commonly used in civilian turbine-engine powered aviation is Jet B, which is used for its enhanced cold-weather performance.
A biorefinery is a refinery that converts biomass to energy and other beneficial byproducts. The International Energy Agency Bioenergy Task 42 defined biorefining as "the sustainable processing of biomass into a spectrum of bio-based products and bioenergy ". As refineries, biorefineries can provide multiple chemicals by fractioning an initial raw material (biomass) into multiple intermediates that can be further converted into value-added products. Each refining phase is also referred to as a "cascading phase". The use of biomass as feedstock can provide a benefit by reducing the impacts on the environment, as lower pollutants emissions and reduction in the emissions of hazard products. In addition, biorefineries are intended to achieve the following goals:
Bioenergy is a type of renewable energy that is derived from plants and animal waste. The biomass that is used as input materials consists of recently living organisms, mainly plants. Thus, fossil fuels are not regarded as biomass under this definition. Types of biomass commonly used for bioenergy include wood, food crops such as corn, energy crops and waste from forests, yards, or farms.
Synthetic fuel or synfuel is a liquid fuel, or sometimes gaseous fuel, obtained from syngas, a mixture of carbon monoxide and hydrogen, in which the syngas was derived from gasification of solid feedstocks such as coal or biomass or by reforming of natural gas.
Neste Oyj is an oil refining and marketing company located in Espoo, Finland. It produces, refines and markets oil products, provides engineering services, and licenses production technologies. Neste has operations in 14 countries.
Pyrolysis oil, sometimes also known as biocrude or bio-oil, is a synthetic fuel with few industrial application and under investigation as substitute for petroleum. It is obtained by heating dried biomass without oxygen in a reactor at a temperature of about 500 °C (900 °F) with subsequent cooling, separation from the aqueous phase and other processes. Pyrolysis oil is a kind of tar and normally contains levels of oxygen too high to be considered a pure hydrocarbon. This high oxygen content results in non-volatility, corrosiveness, partial miscibility with fossil fuels, thermal instability, and a tendency to polymerize when exposed to air. As such, it is distinctly different from petroleum products. Removing oxygen from bio-oil or nitrogen from algal bio-oil is known as upgrading.
Neste MY Renewable Diesel is a vegetable oil refining fuel production process commercialized by the Finnish oil and refining company Neste. Whether as an admixture or in its pure form, the fuel is able to supplement or partially replace conventional diesel without problems. Neste guarantees that every gallon sold meets ASTM D975 and EN 15940 specifications in compliance with OEM standards.
Renewable fuels are fuels produced from renewable resources. Examples include: biofuels, Hydrogen fuel, and fully synthetic fuel produced from ambient carbon dioxide and water. This is in contrast to non-renewable fuels such as natural gas, LPG (propane), petroleum and other fossil fuels and nuclear energy. Renewable fuels can include fuels that are synthesized from renewable energy sources, such as wind and solar. Renewable fuels have gained in popularity due to their sustainability, low contributions to the carbon cycle, and in some cases lower amounts of greenhouse gases. The geo-political ramifications of these fuels are also of interest, particularly to industrialized economies which desire independence from Middle Eastern oil.
Aircraft engines produce gases, noise, and particulates from fossil fuel combustion, raising environmental concerns over their global effects and their effects on local air quality. Jet airliners contribute to climate change by emitting carbon dioxide, the best understood greenhouse gas, and, with less scientific understanding, nitrogen oxides, contrails and particulates. Their radiative forcing is estimated at 1.3–1.4 that of CO2 alone, excluding induced cirrus cloud with a very low level of scientific understanding. In 2018, global commercial operations generated 2.4% of all CO2 emissions.
Biofuel is fuel that is produced from organic matter (biomass), including plant materials and animal waste. It is considered a renewable source of energy that can assist in reducing carbon emissions. The two main types of biofuel currently being produced in Australia are biodiesel and bioethanol, used as replacements for diesel and petrol (gasoline) respectively. As of 2017 Australia is a relatively small producer of biofuels, accounting for 0.2% of world bioethanol production and 0.1% of world biodiesel production.
Jatropha curcas is a species of flowering plant in the spurge family, Euphorbiaceae, that is native to the American tropics, most likely Mexico and Central America. It is originally native to the tropical areas of the Americas from Mexico to Argentina, and has been spread throughout the world in tropical and subtropical regions around the world, becoming naturalized or invasive in many areas. The specific epithet, "curcas", was first used by Portuguese doc Garcia de Orta more than 400 years ago. Common names in English include physic nut, Barbados nut, poison nut, bubble bush or purging nut. In parts of Africa and areas in Asia such as India it is often known as "castor oil plant" or "hedge castor oil plant", but it is not the same as the usual castor oil plant, Ricinus communis.
Second-generation biofuels, also known as advanced biofuels, are fuels that can be manufactured from various types of non-food biomass. Biomass in this context means plant materials and animal waste used especially as a source of fuel.
Algae fuel, algal biofuel, or algal oil is an alternative to liquid fossil fuels that uses algae as its source of energy-rich oils. Also, algae fuels are an alternative to commonly known biofuel sources, such as corn and sugarcane. When made from seaweed (macroalgae) it can be known as seaweed fuel or seaweed oil.
Hydrotreated vegetable oil (HVO) is a biofuel made by the hydrocracking or hydrogenation of vegetable oil. Hydrocracking breaks big molecules into smaller ones using hydrogen while hydrogenation adds hydrogen to molecules. These methods can be used to create substitutes for gasoline, diesel, propane, kerosene and other chemical feedstock. Diesel fuel produced from these sources is known as green diesel or renewable diesel.
Sustainable biofuel is biofuel produced in a sustainable manner. It is not based on petroleum or other fossil fuels. It includes not using plants that are used for food stuff to produce the fuel thus disrupting the world's food supply.
Strict sustainability standards for biofuel in the European Union (EU) are set by the European Commissioner on Energy. Biofuels are considered a renewable alternative to fossil fuels in the transportation sector for the EU. The EU has played a large role in increasing the use of biofuels in member states; however, it has also aimed, to some extent, to mitigate the potential negative impacts of biofuel production. Current EU legislation on biofuels includes a goal to increase renewable energy consumption by 20%, eliminate biofuel feedstock sourced from carbon-rich land, accounting for emissions caused from land use change as well as solely biofuel usage, and reducing greenhouse gas intensities from fuels used in transport and machinery.
D7566 Revision Adds Bioderived Components
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: 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