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Cited by 228Advanced Aircraft Design and TechnologiesHeat transfer and supercritical fluidsAviation Industry Analysis and Trends

Use of sustainable fuels in aviation: a review

Open access
Cabrera, Eduardo, de Sousa, João M. Melo·2022·Energies
DOI 10.3390/en15072440
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Abstract

As the push for carbon-neutral transport continues, the aviation sector is facing increasing pressure to reduce its carbon footprint. Furthermore, commercial air traffic is expected to resume the continuous growth experienced until the pandemic, highlighting the need for reduced emissions. The use of alternative fuels plays a key role in achieving future emission goals, while also lowering the dependency on fossil fuels. The so-called sustainable aviation fuels (SAF), which encompass bio and synthetic fuels, are currently the most viable option, but hydrogen is also being considered as a long-term solution. The present paper reviews the production methods, logistical and technological barriers, and potential for future mass implementation of these alternative fuels. In general, biofuels currently present higher technological readiness levels than other alternatives. Sustainable mass production faces critical feedstock-related challenges that synthetic fuels, together with other solutions, can overcome. All conventional fuel replacements, though with different scopes, will be important in meeting long-term goals. Government support will play an important role in accelerating and facilitating the transition towards sustainable aviation.

AI snapshot

Written from the paper’s full text.

TL;DR

This review surveys sustainable aviation fuel pathways—bio-based drop-in SAF, synthetic power-to-liquid/e-fuels, hydrogen, and battery-electric propulsion—and assesses production, certification, barriers, and policy support. It concludes that drop-in SAFs are the most viable short- and medium-term option, with biofuels at higher readiness but feedstock-limited, while synthetic fuels and hydrogen/electric aircraft face cost or range barriers and are longer-term.

Key findings

  • Aviation accounted for around 2.5% of global CO₂ emissions and 3.5% of global warming including non-CO₂ contributions; 2019 jet kerosene combustion reached 1027 MtCO₂. SAF use remains less than 0.1% of jet kerosene consumption, though SAF can reduce life-cycle carbon emissions up to 80%.
  • ASTM has approved eight conversion pathways; certified blending ratios are 5–50% depending on the process, and D4054 certification takes 3–5 years and costs at least $5 million. HEFA-SPK has powered over 95% of all SAF flights to date.
  • Biofuels currently have higher technology readiness than other alternatives, but sustainable mass production faces feedstock constraints; synthetic PtL/e-fuels avoid biomass feedstock issues but are currently too expensive. Hydrogen and battery aircraft are long-term options with range limits: large battery-powered aircraft are not expected to cover more than about 500 km by 2050, and liquid hydrogen contains 2.5 times more energy per kilogram than kerosene.
  • Policy support is emphasized: ReFuelEU targets 2% SAF at EU airports in 2025 rising to 63% in 2050 for biofuels and 0.7% for e-fuels in 2030. Waste/residue lipids could account for at least 20 million tons of SAF and 20 million tons of renewable diesel, and 2030 global feedstock availability could provide around 135 million tons of SAF per year.

Methods

  • Narrative review of alternative aviation fuels, covering drop-in SAF (bio and synthetic), hydrogen, and battery-electric propulsion, including production methods, certification, logistical/technological barriers, and future implementation.
  • Draws on published literature, ASTM standards (D1655, D4054, D7566), ICAO/CORSIA, IATA, EU ReFuelEU, and third-party data/figures; no primary experimental data or systematic search protocol is reported.
  • Main analysis is a qualitative synthesis and comparison of pathways, feedstocks, blending limits, costs, and policy targets.

Limitations

  • The paper states that a complete, extensive description of possible biofuel feedstocks would fall outside its scope; it also notes that restrictions may apply to the availability of third-party data.
  • No formal limitations section is provided; as a narrative review, it lacks a systematic search/selection method and reports no primary data.
  • Evident from the text: cost, readiness, feedstock, and emissions figures rely on cited third-party sources and projections, which may change as technologies and policies evolve.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.3390/en15072440

Cites

40 of 40 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 120 cited sources checked · 0 supported · 0 flagged

  • Premisecitation

    Blending ratios for certified SAF pathways only allow between 5 and 50% mixing, depending on the conversion process.

    “blending ratios for certified pathways only allow between 5 and 50% mixing, depending on the conversion process.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [27] Chevron (2006). Alternative Jet Fuels, Chevron.

      Not checked in the free run.

  • Premisecitation

    Commercial air traffic is expected to resume the continuous growth experienced until the pandemic.

    “commercial air traffic is expected to resume the continuous growth experienced until the pandemic”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [16] European Organisation for the Safety of Air Navigation (2022, January 10). EUROCONTROL Forecast Update 2021–2027. Available online: https://www.eurocontrol.int/publication/eurocontrol-forecast-update-2021-2027.

      Not checked in the free run.

  • Premisenone given

    Power-to-liquids options are currently too expensive in comparison with biogenic feedstocks.

    “However, the latter are currently too expensive in comparison with the former”
    Quote in the paperNot a substantial claim
  • Premisecitation

    SAF can decrease life cycle carbon emissions up to 80%.

    “Studies show that SAF can decrease life cycle carbon emissions up to 80% [29]”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [29] (2022, January 07). What is Sustainable Aviation Fuel (SAF)?. Available online: https://www.bp.com/en/global/air-bp/news-and-views/views/what-is-sustainable-aviation-fuel-saf-and-why-is-it-important.html.

      Not checked in the free run.

  • Interpretationreasoning

    Drop-in alternatives to conventional jet kerosene are the best short- and medium-term choice.

    ““Drop-in” alternatives to conventional jet kerosene emerge as the best short-and medium-term choice”
    Quote in the paperSubstantial claim
  • May combine two claims. 57
  • Classified as probably not a substantial claim. 33

  • May combine two claims.

    Premisecitation

    The ASTM D4054 certification process requires different fuel volumes in each tier and takes 3-5 years with a cost of at least $5 million on candidate fuel producers.

    “The comprehensive and meticulous method set by D4054 requires different fuel volumes in each different tier, and the 3-5 year process has a cost of at least $5 million on candidate fuel producers [37,38].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [37] Heyne, 2021, Sustainable aviation fuel prescreening tools and procedures, Fuel source

      Not checked in the free run.

    • cites [38] Office of Energy Eficiency and Renewable Energy (2022, January 13). Sustainable Aviation Fuels: Review of Technical Pathways, Available online: https://www.energy.gov/sites/prod/files/2020/09/f78/beto-sust-aviation-fuel-sep-2020.pdf.

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    In January 2020, ASTM approved a Fast Track Annex to D4054, but new fuels approved under this process are limited to a 10% blend percentage.

    “in January 2020, ASTM approved a Fast Track Annex to D4054, but new fuels approved under this process are limited to a 10% blend percentage [38].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [38] Office of Energy Eficiency and Renewable Energy (2022, January 13). Sustainable Aviation Fuels: Review of Technical Pathways, Available online: https://www.energy.gov/sites/prod/files/2020/09/f78/beto-sust-aviation-fuel-sep-2020.pdf.

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Premisenone given

    Other methods such as using solar energy are still in the early development phases.

    “other methods, such as using solar energy, are still in the early development phases.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Biofuels from oil feedstocks used to be mostly produced from first-generation feedstocks such as palm oil and soybean, but these can lead to sustainability issues.

    “Biofuels from oil feedstocks used to be mostly produced from first-generation feedstocks, such as palm oil and soybean [41], but these can lead to sustainability issues”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [41] International Civil Aviation Organization (2017). Sustainable Aviation Fuels Guide, International Civil Aviation Organization.

      Not checked in the free run.

  • May combine two claims.

    Interpretationcitation

    Future fuel efficiency progress is not expected to match the projected increase in air traffic, hence will be insufficient.

    “future progress is not expected to match the projected increase in air traffic, hence will therefore be insufficient”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [21] International Civil Aviation Organization (2022, January 07). Trends in Emissions that Affect Climate Change. Available online: https://www.icao.int/environmental-protection/Pages/ClimateChange_Trends.aspx.

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S2 (checkable).

    Interpretationreasoning

    To accomplish the required results, it is necessary to lower and eventually end the dependency of commercial aviation on fossil fuels.

    “in order to accomplish the required results, it becomes necessary to lower and eventually end the dependency of commercial aviation on fossil fuels.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Aviation is widely seen as the hardest sector to decarbonize, technologically and economically.

    “aviation is widely seen as the hardest sector to decarbonize, whether it is looked at from a technological or an economical standpoint [4].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [4] Searle, S., Pavlenko, N., Kharina, A., and Giuntoli, J. (2019). Long-Term Aviation Fuel Decarbonization: Progress, Roadblocks, and Policy Opportunities, International Council on Clean Transportation.

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    SAF can lower emissions of soot, sulfur oxides, and ultrafine particles, and mitigate the climate impact of contrails.

    “while also lowering emissions of other pollutants, such as soot [30], sulfur oxides, and ultrafine particles [31], as well as mitigating the climate impact of contrails [32].”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [30] Gaspar, 2016, Impact of alternative fuels on the operational and environmental performance of a small turbofan engine, Energ. Convers. Manag. source

      Not checked in the free run.

    • cites [31] Gladstein, Neandross & Associates (2020). Sustainable Aviation Fuel: Greenhouse Gas Reductions from Bay Area Commercial Aircraft, Gladstein, Neandross & Associates.

      Not checked in the free run.

    • cites [32] Narciso, M., and Sousa, J.M.M. (2021). Influence of Sustainable Aviation Fuels on the Formation of Contrails and Their Properties. Energies, 14. source

      Not checked in the free run.

  • May combine two claims.

    Premisereasoning

    Second-generation biofuels are comprised of non-food crops and alternative raw materials that do not compete with edible feedstocks for land, and are therefore more likely to meet sustainability standards.

    “Second-generation biofuels are comprised of non-food crops and other alternative raw materials that do not seek to compete with edible feedstocks for land usage, and are therefore more likely to meet the sustainability standards required.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S4 (based).

    Interpretationnone given

    Sustainable mass production faces critical feedstock-related challenges that synthetic fuels, together with other solutions, can overcome.

    “Sustainable mass production faces critical feedstock-related challenges that synthetic fuels, together with other solutions, can overcome.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    By 2019 more than a quarter of a million SAF flights had been performed by more than 45 commercial airlines.

    “by 2019 more than a quarter of a million SAF flights had been performed by more than 45 commercial airlines [9]”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [9] International Air Transport Association (2021). Fly Net Zero Information Pack, International Air Transport Association.

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing), S4 (based).

    Interpretationnone given

    Government support will play an important role in accelerating and facilitating the transition towards sustainable aviation.

    “Government support will play an important role in accelerating and facilitating the transition towards sustainable aviation.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Current generation aircraft are 20% more efficient than the previous generation and 85% more efficient than those of the 1960s.

    “the current generation of aircraft being 20% more efficient than the previous generation, and 85% more than those of the 1960s [2]”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [2] International Energy Agency (2022, January 05). Internatonal Energy Agency, Paris. Available online: https://www.iea.org/reports/aviation.

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S4 (based). May combine two claims.

    Interpretationnone given

    SAF, encompassing bio and synthetic fuels, are currently the most viable option, but hydrogen is also being considered as a long-term solution.

    “The so-called sustainable aviation fuels (SAF), which encompass bio and synthetic fuels, are currently the most viable option, but hydrogen is also being considered as a long-term solution.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Biofuels can be produced from renewable carbon-based material, and associated carbon life cycle emissions can be significantly reduced because some CO2 is reabsorbed by the next generation of crops.

    “Since plants are the most common sources for biofuel production, associated carbon life cycle emissions can be significantly reduced, as some of the CO 2 will be reabsorbed by the next generation of crops [39].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [39] Air Transport Action Group (2011). Beginner’s Guide to Aviation Biofuels, Air Transport Action Group.

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S2 (checkable), S4 (based).

    Interpretationnone given

    All conventional fuel replacements, though with different scopes, will be important in meeting long-term goals.

    “All conventional fuel replacements, though with different scopes, will be important in meeting long-term goals.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S4 (based). May combine two claims.

    Interpretationnone given

    The use of alternative fuels plays a key role in achieving future emission goals, while also lowering dependency on fossil fuels.

    “The use of alternative fuels plays a key role in achieving future emission goals, while also lowering the dependency on fossil fuels.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisenone given

    Currently biogenic feedstocks are most used, but sustainability poses a major obstacle to larger-scale applications.

    “Currently, biogenic feedstocks are most used, but sustainability poses as a major obstacle to larger-scale applications”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Wastes from anthropogenic activities, especially industrial by-products, can also be considered a separate feedstock category.

    “Sometimes wastes from anthropogenic activities, especially industrial by-products, can also be considered as a separate feedstock category [47].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [47] Commercial Aviation Alternative Fuels Initiative (2022, January 16). Feedstocks. Available online: https://www.caafi.org/focus_areas/feedstocks.html.

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S4 (based).

    Interpretationnone given

    Biofuels currently present higher technological readiness levels than other alternatives.

    “In general, biofuels currently present higher technological readiness levels than other alternatives.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    One main advantage of producing SAF in petroleum refineries is that higher capacities allow higher fuel output and offer significant cost reduction opportunities.

    “One of the main advantages of producing SAF in petroleum refineries is the fact that the higher capacities of those refineries allows for higher fuel output, and offers significant cost reduction opportunities [72].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [72] Tanzil, 2021, Production of Sustainable Aviation Fuels in Petroleum Refineries: Evaluation of New Bio-Refinery Concepts, Front. Energy Res. source

      Not checked in the free run.

  • May combine two claims.

    Premiseown data

    Annex A7 of D7566 was approved in May 2020 and covers production and use of a type of synthesized paraffinic kerosene from hydrocarbon-hydroprocessed esters and fatty acids.

    “The final annex to D7566, namely Annex A7, was approved in May 2020 and it covers for the production and use of a type of synthesized paraffinic kerosene from hydrocarbonhydroprocessed esters and fatty acids.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    In 2018 co-processing of renewable content with conventional crude oil was approved and added to Annex A1 of ASTM D1655.

    “However, in 2018 co-processing of renewable content with conventional crude oil was approved and added to Annex A1 of ASTM D1655 [70].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [70] Commercial Aviation Alternative Fuels Initiative (2022, January 20). Co-Processing Provision Approved and Added to ASTM 1655 Annex A1, Enables Renewable Feedstocks in Jet Fuel. Available online: https://www.caafi.org/news/NewsItem.aspx?id=10408.

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Halophytes are salt-tolerant grasses that can grow in areas where plant life normally could not prosper.

    “Halophytes are a group of salt-tolerant grasses that can grow in areas where plant life normally could not prosper [39].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [39] Air Transport Action Group (2011). Beginner’s Guide to Aviation Biofuels, Air Transport Action Group.

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Feedstocks suitable for jet fuel production through catalytic hydrothermolysis are similar to those of the HEFA pathway, with carinata used during the qualification process.

    “The feedstocks suitable for jet fuel production through CH are similar to those of the HEFA pathway, with carinata being used during the qualification process [66][67][68].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [66][67][68]

      Not checked in the free run.

  • May combine two claims.

    Interpretationcitation

    Use of only a small percentage of degraded/non-arable soil could boost current SAF production numbers without competing with edible crops or being dependent on their rotation timelines.

    “A use of only a small percentage of this type of soil could boost current SAF production numbers [6], without the need to compete with edible crops or being dependent on their rotation timelines [50].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [6] World Economic Forum (2020). Clean Skies for Tomorrow: Sustainable Aviation Fuels as a Pathway to Net-Zero Aviation, World Economic Forum.

      Not checked in the free run.

    • cites [50] Hari, 2015, Aviation biofuel from renewable resources: Routes, opportunities and challenges, Renew. Sustain. Energ. Rev. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    HC-HEFA hydroprocesses bioderived hydrocarbons obtained from oils found in Botryococcus braunii, the only feedstock source for this conversion process.

    “The difference lies in that, unlike the fatty acids or fatty acid esters found in HEFA production, this addition describes the hydroprocessing of bioderived hydrocarbons obtained from oils found in a specific algae (Botryococcus braunii), the only feedstock source for this conversion process [36,46,65,66,69].”
    Quote in the paperNot a substantial claim0 of 5 sources checked
    • cites [36] Commercial Aviation Alternative Fuels Initiative (2022, January 15). Fuel Qualification. Available online: https://www.caafi.org/focus_areas/fuel_qualification.html.

      Not checked in the free run.

    • cites [46] PtX Hub (2022, January 13). How is Sustainable Aviation Fuel Produced?—Conversion Processes Explained. Available online: https://ptx-hub.org/how-is-saf-produced-conversion-processes-explained/.

      Not checked in the free run.

    • cites [65] SkyNRG (2022, January 20). Technology. Available online: https://skynrg.com/sustainable-aviation-fuel/technology/.

      Not checked in the free run.

    • cites [66] International Air Transport Association (2020). Fact Sheet 2: Sustainable Aviation Fuel: Technical Certification, International Air Transport Association.

      Not checked in the free run.

    • cites [69] Green Car Congress (2022, January 20). ASTM Approves 7th Annex to D7566 Sustainable Jet Fuel Specification: HC-HEFA. Available online: https://www.greencarcongress.com/2020/05/20200514-ihi.html.

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing). May combine two claims.

    Interpretationreasoning

    Though research is not as advanced as with bio SAFs, e-fuels could potentially become the best choice for short- and medium-term decarbonization efforts.

    “which in turn implies that, though research is not as advanced as is the case with bio SAFs, e-fuels could potentially become the best choice for short-and medium-term decarbonization efforts.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    SOEL is a recent, less developed technology compared with AEL and PEMEL, just now entering the market, but considered a more promising long-term option for carbon-neutrality pursuit.

    “Solid oxide electrolysis (SOEL) is a recent, less developed technology when compared with AEL and PEMEL that is just now entering the market [83,85], but it is considered a more promising long-term option for carbon-neutrality pursuit [86].”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [83] Wulf, 2020, Review of Power-to-X Demonstration Projects in Europe, Front. Energy Res. source

      Not checked in the free run.

    • cites [85] Varone, 2015, Power to liquid and power to gas: An option for the German Energiewende, Renew. Sustain. Energ. Rev. source

      Not checked in the free run.

    • cites [86] Herz, 2021, Economic assessment of Power-to-Liquid processes—Influence of electrolysis technology and operating conditions, Appl. Energy source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Cover crops can improve soil quality compared with monocropping, reduce erosion, improve water infiltration and carbon sequestration, though sustainability benefits are not completely clear and need further analysis.

    “cover crops can also improve soil quality in comparison with monocropping [39], as it reduces erosion and improves water infiltration and carbon sequestration [6], though the sustainability benefits of this practice are still not completely clear and need further analysis”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [6] World Economic Forum (2020). Clean Skies for Tomorrow: Sustainable Aviation Fuels as a Pathway to Net-Zero Aviation, World Economic Forum.

      Not checked in the free run.

    • cites [39] Air Transport Action Group (2011). Beginner’s Guide to Aviation Biofuels, Air Transport Action Group.

      Not checked in the free run.

    • cites [48] O’Malley, J., Pavlenko, N., Kharina, A., and Searle, S. (2021). Estimating Sustainable Aviation Fuel Feedstock Availability to Meet Growing European Union Demand, International Council on Clean Transportation.

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Providing the FT process employs iron or cobalt catalysts, ASTM does not restrict feedstock origin for drop-in FT fuels, and this pathway can already be used in commercial aircraft up to 50% blends.

    “Providing that the FT process employs iron or cobalt catalysts, ASTM does not restrict the feedstock origin for drop-in FT fuels, and so this pathway can already be used in commercial aircraft up to 50% blends [63,74].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [63] Schmidt, 2018, Power-to-Liquids as Renewable Fuel Option for Aviation: A Review, Chem. Ing. Tech. source

      Not checked in the free run.

    • cites [74] Ricardo Energy and Environment (2020). Targeted Aviation Advanced Biofuels Demonstration Competition—Feasibility Study. Report for Department for Transport, UK, Ricardo Energy and Environment.

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Camelina can be used as a rotational cover crop.

    “Camelina can be used as a rotational cover crop [6].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [6] World Economic Forum (2020). Clean Skies for Tomorrow: Sustainable Aviation Fuels as a Pathway to Net-Zero Aviation, World Economic Forum.

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Methanol is currently produced especially from syngas through a sequence of exothermic reactions and requires a stoichiometric H2/CO ratio of 2 for maximum efficiency.

    “Methanol is currently produced especially from syngas, through a sequence of exothermic reactions, and requires a stoichiometric H 2 /CO ratio of 2 for maximum efficiency [79].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [79] National Energy Technology Laboratory (2022, January 08). 10.3. Syngas Conversion to Methanol, Available online: https://netl.doe.gov/research/coal/energy-systems/gasification/gasifipedia/methanol.

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Swedish Biofuels and Byogy are developing a variation of the ATJ process that can produce jet fuel with higher aromatic content (ATJ-SKA) through an aromatization step, currently in Phase 1 Testing of D4054.

    “Finally, Swedish Biofuels and Byogy are currently developing a variation of the ATJ process that can produce jet fuel with a higher level of aromatic content (ATJ-SKA) through the addition of an aromatization step, which is currently in Phase 1 Testing of D4054 [36,67].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [36] Commercial Aviation Alternative Fuels Initiative (2022, January 15). Fuel Qualification. Available online: https://www.caafi.org/focus_areas/fuel_qualification.html.

      Not checked in the free run.

    • cites [67] Directorate-General for Energy (2017). High Biofuel Blends in Aviation, European Commission.

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    HEFA+ has a higher freezing point, requires fewer processing steps, and has a production cost advantage over HEFA-SPK.

    “This leads to a higher freezing point, which in turn means that less processing steps are required, giving it a production cost advantage over HEFA-SPK [74].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [74] Ricardo Energy and Environment (2020). Targeted Aviation Advanced Biofuels Demonstration Competition—Feasibility Study. Report for Department for Transport, UK, Ricardo Energy and Environment.

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Camelina is a non-edible energy crop with high lipid oil content, used as feedstock for fuel production, and leftover material can be used as feed supplement for livestock.

    “Camelina (Camelina sativa) falls under this category.It is a non-edible energy crop with a high lipid oil content, its main use is precisely as a feedstock for fuel production and, after the oil extraction process, leftover material can also be used as feed supplement for livestock [39].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [39] Air Transport Action Group (2011). Beginner’s Guide to Aviation Biofuels, Air Transport Action Group.

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    There is not a consensus regarding sustainability and potential for GHG reduction in co-processing, with some companies arguing that fuel from co-processing should be ineligible for SAF classification.

    “However, there is not a consensus regarding the sustainability and potential for GHG reduction in this process, with some companies arguing that fuel resultant from co-processing should be ineligible for SAF classification [73].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [73] Environmental + Energy Leader (2022, January 20). Biofuel, Transportation Companies Ask Congress To Exclude Co-Processed Petroleum from Sustainable Aviation Fuel Credit. Available online: https://www.environmentalleader.com/2021/12/biofuel-transportation-companies-ask-congress-to-exclude-co-processed-petroleum-from-sustainable-aviation-fuel-credit/.

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Although electrolysis is still far from being the most industrially used method to obtain H2, it is a growing market and the most promising process to achieve carbon-free hydrogen production.

    “Although it is still far from being the most industrially used method to obtain H 2 [81], it is a growing market and the most promising process to achieve carbon-free hydrogen production [82].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [81] International Energy Agency (2022, January 05). The Future of Hydrogen. International Energy Agency, Paris, Available online: https://www.iea.org/reports/the-future-of-hydrogen.

      Not checked in the free run.

    • cites [82] Office of Energy Efficiency and Renewable Energy (2022, January 09). Hydrogen Production: Electrolysis, Available online: https://www.energy.gov/eere/fuelcells/hydrogen-production-electrolysis.

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Catalytic hydrothermolysis is one of the two pathways most recently certified for commercial use in 2020, with a maximum blending ratio of 50% (Annex A6 of D7566).

    “Catalytic hydrothermolysis is one of the two pathways that were most recently certified for commercial use -again, with a maximum blending ratio of 50%-in 2020 (Annex A6 of D7566 in the case of CH).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Annex A6 of D7566

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Jatropha has long-lasting production challenges: low seed yield, susceptibility to viral infections and pests, and high complexity and cost of efficient oil extraction.

    “These include low seed yield (and limited biogenetic studies on technologies that could help boost breeding programs, such as cloning and gene expression), susceptibility to viral infections and pests such as insects and rodents, and high complexity and cost of efficient oil extraction methods [51].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [51] Jacob-Lopes, E., and Zepka, L.Q. (2017). Jatropha Biofuel industry: The challenges. Frontiers in Bioenergy and Biofuels, IntechOpen. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Advancements in direct CO2 to methanol conversion would eliminate the need for CO2 reduction through RWGS and improve cost efficiency of the whole production line.

    “There have been, however, advancements in direct CO 2 to methanol conversion [80], which would eliminate the need for CO 2 reduction through RWGS, and thus improve cost efficiency of the whole production line.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [80] Bos, 2015, A novel condensation reactor for efficient CO2 to methanol conversion for storage of renewable electric energy, Chem. Eng. J. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Jatropha is poisonous to humans and animals, so leftovers from oil extraction cannot be reused as fodder.

    “It is also poisonous both to humans and animals so, unlike Camelina, leftovers from the oil extraction cannot be reused as fodder [49].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [49] Farm Energy eXtension (2022, January 16). Jatropha: Biodiesel and More. Available online: https://farm-energy.extension.org/jatropha-biodiesel-and-more/.

      Not checked in the free run.

  • May combine two claims.

    Interpretationcitation

    Hydrogen- and battery-powered aircraft have limited potential flight coverage but can still play an important role in decarbonizing aviation.

    “and though their potential flight coverage is limited, they can still play an important role in decarbonizing aviation, which is why numerous projects involving several airlines are currently under development [101].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [101] Aviation Today (2022, January 09). 10 Airlines That Made Electric and Hydrogen-Powered Aircraft Investments, Partnerships in 2021. Available online: https://www.aviationtoday.com/2022/01/01/10-airlines-made-electric-hydrogen-powered-aircraft-investments-partnerships-2021/.

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Studies show that HHO has advantages over H2 in reducing CO and CO2, and increased efficiency and reduction in some GHG emissions have been reported with duel-fuel setups in diesel engines.

    “Studies show that HHO has advantages over H 2 in reducing CO and CO 2 , and increased efficiency and reduction in some GHG emissions have been reported with duel-fuel setups in diesel engines [88].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [88] Sekar, 2022, Optimisation of dry cell electrolyser and hydroxy gas production to utilise in a diesel engine operated with blends of orange peel oil in dual-fuel mode, Int. J. Hydrogen Energy source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Unlike SAFs, which rely mostly on carbon offsetting to reduce life cycle emissions, hydrogen- and battery-powered aircraft would eliminate in-flight CO2 emissions.

    “Unlike SAFs, which rely mostly on carbon offsetting to reduce life cycle emissions, the latter technologies would eliminate in-flight CO 2 emissions, and though their potential flight coverage is limited, they can still play an important role in decarbonizing aviation, which is why numerous projects involving several airlines are currently under development [101].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [101] Aviation Today (2022, January 09). 10 Airlines That Made Electric and Hydrogen-Powered Aircraft Investments, Partnerships in 2021. Available online: https://www.aviationtoday.com/2022/01/01/10-airlines-made-electric-hydrogen-powered-aircraft-investments-partnerships-2021/.

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    The European Commission's ReFuelEU Aviation mandate sets specific targets for SAF integration in EU airports, from 2% in 2025 to 63% in 2050, for biofuels, and to 0.7% for 2030, for e-fuels.

    “Another way to promote SAF use is through legislation, such as the European Commission's ReFuelEU Aviation, a mandate that sets specific targets for SAF integration in EU airports, from 2% in 2025 to 63% in 2050, for biofuels, and to 0.7% for 2030, for e-fuels [114].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [114] GreenAir (2022, January 27). European Commission’s ReFuelEU Aviation Proposal Details SAF Blending Obligation on Fuel Suppliers. Available online: https://www.greenairnews.com/?p=1374.

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Interpretationcitation

    Though water demand is substantially lower compared with biofuel production, sustainability issues may emerge if the used water source conflicts with agricultural land requirements, and such factors need to be evaluated before future large-scale facilities enter production.

    “Though demand is substantially lower when compared with biofuel production [75,78], sustainability issues may emerge if, for example, the used water source conflicts with agricultural land requirements, and such factors need to be evaluated before any future large-scale facilities enter production.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [75] German Environment Agency (2016). Power-to-Liquids: Potentials and Perspectives for the Future Supply of Renewable Aviation Fuel, German Environment Agency.

      Not checked in the free run.

    • cites [78] International Civil Aviation Organization (2019). Power-to-Liquids (PTL): Sustainable Fuels for Aviation, International Civil Aviation Organization.

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    There is some skepticism regarding the capability of biogenic feedstocks to address expected future fuel demand without compromising obligations.

    “There is some skepticism regarding the capability of biogenic feedstocks to address expected future fuel demand without compromising some of these obligations [63].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [63] Schmidt, 2018, Power-to-Liquids as Renewable Fuel Option for Aviation: A Review, Chem. Ing. Tech. source

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    The CO2 cascade process would still increase CO2 atmospheric levels, and so it is not a realistic option towards achieving future goals.

    “However, this process would still nevertheless increase CO 2 atmospheric levels, and so it is not a realistic option towards achieving future goals.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Biofuels are closer to wide-scale commercialization than other alternatives, but no pathway has yet achieved the highest technological readiness level.

    “Biofuels are closer to wide-scale commercialization than other alternatives, but, despite increasing number of flights using SAFs, especially employing HEFA-SPK, no pathway has yet achieved the highest technological readiness level [74]”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [74] Ricardo Energy and Environment (2020). Targeted Aviation Advanced Biofuels Demonstration Competition—Feasibility Study. Report for Department for Transport, UK, Ricardo Energy and Environment.

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Water is necessary for hydrogen production (1.3-1.4 liters of water per liter of jet fuel), as well as cooling and heating purposes during other phases.

    “Water is necessary for hydrogen production (1.3-1.4 liters of water per liter of jet fuel [75]), as well as cooling and heating purposes during other phases [76].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [75] German Environment Agency (2016). Power-to-Liquids: Potentials and Perspectives for the Future Supply of Renewable Aviation Fuel, German Environment Agency.

      Not checked in the free run.

    • cites [76] Neuling, 2020, Power-to-Liquid fuels for aviation—Processes, resources and supply potential under German conditions, Appl. Energy source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    One main advantage of SOEL is its high operational temperature range (up to 1000°C), enabling waste heat reuse from exothermic FT reaction or methanol synthesis, reducing energy demand and resulting in significantly higher efficiencies than AEL or PEMEL.

    “One of the main advantages of this technology is the high operational temperature range (up to 1000 • C [84]); this enables that waste heat to be reused from both the exothermic FT reaction or methanol synthesis [75], which reduces the energy demand and results in significantly higher efficiencies than AEL or PEMEL [87].”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [84] Gandía, L.M., Arzamendi, G., and Diéguez, P.M. (2013). Chapter 2–Water Electrolysis Technologies. Renewable Hydrogen Technologies, Elsevier. source

      Not checked in the free run.

    • cites [75] German Environment Agency (2016). Power-to-Liquids: Potentials and Perspectives for the Future Supply of Renewable Aviation Fuel, German Environment Agency.

      Not checked in the free run.

    • cites [87] Buttler, 2018, Current status of water electrolysis for energy storage, grid balancing and sector coupling via power-to-gas and power-to-liquids: A review, Renew. Sustain. Energ. Rev. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    PtL processes are relying on new improvements in both high temperatures and co-electrolysis, and while currently not cost-competitive with biofuels, it is expected that in the long-term this pathway becomes the most economically competitive.

    “Power-to-liquid processes are also relying on new improvements in both high temperatures and co-electrolysis, and while at the moment they are nowhere near as close to compete with biofuels in terms of cost, it is expected that in the long-term this pathway becomes the most economically competitive [6].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [6] World Economic Forum (2020). Clean Skies for Tomorrow: Sustainable Aviation Fuels as a Pathway to Net-Zero Aviation, World Economic Forum.

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Hydrogen consumption has been progressively increasing in recent decades, but not sustainably, being mostly produced from gasification of coal or reforming of natural gas, with associated CO2 emissions exceeding 800 million tons per year.

    “Hydrogen consumption has been progressively increasing in recent decades, but not on a sustainable manner, being mostly produced from gasification of coal or reforming of natural gas, with associated CO 2 emissions exceeding 800 million tons per year [81].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [81] International Energy Agency (2022, January 05). The Future of Hydrogen. International Energy Agency, Paris, Available online: https://www.iea.org/reports/the-future-of-hydrogen.

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    Drop-in fuels have the advantage over other alternatives due to being more matured technologies and because their compatibility with current aircraft and logistics makes it possible to address the urgency of the problem.

    “Drop-in fuels have the advantage on other alternatives, not only due to being more matured technologies, but also because their compatibility with current aircraft and logistics makes it possible to address the urgency of the problem.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S4 (based). May combine two claims.

    Interpretationnone given

    Within drop-in fuels, jet fuel from biogenic sources is currently easier and less expensive to produce in meaningful quantities, and can be achieved through several different pathways.

    “Within this category, jet fuel from biogenic sources is currently easier and less expensive to produce in meaningful quantities, and can be achieved through several different pathways.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Most fuel production pathways also generate other products, and even if production is optimized to obtain jet fuel, valorization of co-products should not be neglected.

    “In addi-tion, most fuel production pathways also generate other products, and even if production is optimized to obtain jet fuel, valorization of co-products should not be neglected [83].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [83] Wulf, 2020, Review of Power-to-X Demonstration Projects in Europe, Front. Energy Res. source

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    The combination of these issues produces negative effects on cost-effectiveness of SAFs, which could lead to deceleration in decarbonization efforts and prevent the sector from achieving set objectives.

    “The combination of all these issues produce negative effects on the cost-effectiveness of SAFs, which, if these problems were to be left unaddressed, and the economic viability of these fuels remained questioned, could lead to a deceleration in the decarbonization efforts, thereby undoubtedly preventing the sector from achieving the set objectives for the next decades.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    Hydrogen turbine aircraft are expected to be capable of flying larger distances, but not expected to cover long-distance flights.

    “H 2 fuel cell aircraft in development are only targeting short-range flights, and though hydrogen turbine aircraft are expected to be capable of flying larger distances, it is not expected that they will be able to cover long-distance flights [6].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [6] World Economic Forum (2020). Clean Skies for Tomorrow: Sustainable Aviation Fuels as a Pathway to Net-Zero Aviation, World Economic Forum.

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Another possible feature of SOEL is co-electrolysis of CO2 and steam to produce syngas, which would eliminate the need for RWGS, but this technology is in an early development stage.

    “Another possible feature form SOEL is the ability of co-electrolysis of CO 2 and steam to produce syngas, which would be of extreme interest since it would also eliminate the need for RWGS, but this technology is in an early development stage [63,87].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [63] Schmidt, 2018, Power-to-Liquids as Renewable Fuel Option for Aviation: A Review, Chem. Ing. Tech. source

      Not checked in the free run.

    • cites [87] Buttler, 2018, Current status of water electrolysis for energy storage, grid balancing and sector coupling via power-to-gas and power-to-liquids: A review, Renew. Sustain. Energ. Rev. source

      Not checked in the free run.

  • May combine two claims.

    Interpretationcitation

    Hybrid electric systems combining electric and combustion engines can provide a better alternative since they explore advantages of both systems, and will play an essential role in maturing electric aircraft technology.

    “Hybrid electric systems that combine electric and combustion engines can, therefore, provide a better alternative since these explore the advantages of both systems, and will also play an essential role in maturing electric aircraft technology [9].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [9] International Air Transport Association (2021). Fly Net Zero Information Pack, International Air Transport Association.

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    CO2 from fossil origin is not a sustainable long-term solution but could be of interest in the short-term to prove production of scale.

    “CO 2 from fossil origin is not a sustainable long-term solution but could be of interest in the short-term to prove production of scale [89].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [89] World Economic Forum (2020). Joint Policy Proposal to Accelerate the Deployment of Sustainable Aviation Fuels in Europe. A Clean Skies for Tomorrow Publication, World Economic Forum.

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    The two-step redox cycle guarantees that syngas and O2 are generated in separate steps, which avoids formation of explosive mixtures while also removing the necessity for high-temperature gas separation.

    “The two-step redox cycle guarantees that the syngas and O 2 are generated in separate steps, which avoids the formation of explosive mixtures while also removing the necessity for high-temperature gas separation [95].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [95] Rutz, 2022, Drop-in fuels from sunlight and air, Nature source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    DAC is still an underdeveloped technology, and disputes regarding its feasibility for larger scale production due to high operating costs are ongoing.

    “However, at the moment this is still an underdeveloped technology, and disputes regarding its feasibility for larger scale production due to high operating costs are ongoing [90].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [90] Keith, 2018, A Process for Capturing CO2 from the Atmosphere, Joule source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    E-Fan X, an Airbus partnership with Rolls-Royce and Siemens, was developed with the goal of building a hybrid electric demonstrator that could accommodate 50-100 passengers, but was canceled in 2020 before any flights were made.

    “E-Fan X, an Airbus partnership with Rolls-Royce and Siemens, was developed with the goal of building a hybrid electric demonstrator that could accommodate 50-100 passengers, but was canceled in 2020 before any flights were made [110].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [110] Airbus (2022, January 27). E-Fan X: A Giant Leap Towards Zero-Emission Flight. Available online: https://www.airbus.com/en/innovation/zero-emission/electric-flight/e-fan-x.

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Gasoline molecules have 4-12 carbon atoms.

    “gasoline ranges from molecules with 4-12 carbon atoms”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [38] Office of Energy Eficiency and Renewable Energy (2022, January 13). Sustainable Aviation Fuels: Review of Technical Pathways, Available online: https://www.energy.gov/sites/prod/files/2020/09/f78/beto-sust-aviation-fuel-sep-2020.pdf.

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S2 (checkable), S4 (based).

    Interpretationnone given

    Synthetic fuels, especially from PtL methods, will likely become a protagonist in decarbonization, once current technological barriers are surpassed.

    “Synthetic fuels, especially from PtL methods, will likely become a protagonist in decarbonization, once current technological barriers are surpassed.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Interpretationnone given

    Hydrogen- and battery-powered aircraft can contribute, in the long term, to eliminate fossil dependency.

    “Similarly, hydrogen-and battery-powered aircraft can contribute, in the long term, to eliminate fossil dependency.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Jet fuel molecules have 8-16 carbon atoms.

    “Jet fuel, on the other hand, is a middle distillate of the two products-its molecules have 8-16 carbon atoms.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [38] Office of Energy Eficiency and Renewable Energy (2022, January 13). Sustainable Aviation Fuels: Review of Technical Pathways, Available online: https://www.energy.gov/sites/prod/files/2020/09/f78/beto-sust-aviation-fuel-sep-2020.pdf.

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Diesel molecules vary between 8 and 23 carbon atoms.

    “diesel can vary between 8 and 23 carbon atoms”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [38] Office of Energy Eficiency and Renewable Energy (2022, January 13). Sustainable Aviation Fuels: Review of Technical Pathways, Available online: https://www.energy.gov/sites/prod/files/2020/09/f78/beto-sust-aviation-fuel-sep-2020.pdf.

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Jet fuel additives include anti-static chemicals, deicing agents, anticorrosive agents, and antibacterial agents.

    “Among the additives used in jet fuel are anti-static chemicals, deicing agents, anticorrosive agents, and antibacterial agents [35,38,115]”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [35] Chevron (2007). Aviation Fuels: Technical Review, Chevron.

      Not checked in the free run.

    • cites [38] Office of Energy Eficiency and Renewable Energy (2022, January 13). Sustainable Aviation Fuels: Review of Technical Pathways, Available online: https://www.energy.gov/sites/prod/files/2020/09/f78/beto-sust-aviation-fuel-sep-2020.pdf.

      Not checked in the free run.

    • cites [115] Interesting Engineering (2022, January 27). What is the Difference between Jet Fuel and Gasoline?. Available online: https://interestingengineering.com/whats-the-difference-between-jet-fuel-and-gasoline.

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    Specification regarding approval and use of additives in jet fuel is more complex than for non-aviation fuels, with some additives mandatory and others optional, because of the particularities of air travel.

    “due to the particularities of air travel, specification regarding approval and use of additives is more complex, with some being mandatory while others are optional.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: The particularities of air travel make the specification for approval and use of additives more complex.

  • Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing). May combine two claims.

    Interpretationreasoning

    Future technological breakthroughs in emission-reducing additives are likely to be applied to SAF and could help boost their environmental benefits.

    “future technological breakthroughs are likely to be applied to SAF as well, which could help in boosting their environmental benefits.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning

    The main difference between jet fuel and other fuels lies in the hydrocarbons that compose each type, most importantly the number of carbon atoms.

    “The main difference lies in the hydrocarbons that compose each type of fuel, most importantly the number of carbon atoms.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Required emissions reductions to meet the 2050 net-zero goal are obtained through technology developments, operations and infrastructure improvements, use of sustainable aviation fuels, and offsets and other carbon mitigation options.

    “Required emissions reductions are obtained through technology developments (T), operations and infrastructure improvements (O), use of sustainable aviation fuels (F), and offsets and other carbon mitigation options (M).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [17] Air Transport Action Group (2021). Waypoint 2050, Air Transport Action Group.

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning

    Jet fuel specifications must inherently differ from those of other fuels such as gasoline and diesel because air travel faces different and more challenging operating conditions.

    “Due to the different and more challenging operating conditions faced by air travel, jet fuel specifications must inherently differ from other types of fuels, such as gasoline and diesel.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: Air travel faces different and more challenging operating conditions than other fuel uses.
76 of 76

  • The paper relies on this without support.

    The need for sustainable aviation is undeniable.

    “The need for sustainable aviation is undeniable as it is expected that the sector will occupy an increasingly prominent position in global transportation.”

  • The paper relies on this without support.

    Sustainable fuels will play an important role in the transition to carbon neutrality.

    “Sustainable fuels will play an important role in this transition.”

  • The paper relies on this without support.

    Air travel faces different and more challenging operating conditions than other fuel uses.

    “Due to the different and more challenging operating conditions faced by air travel”

  • The paper relies on this without support.

    The particularities of air travel make the specification for approval and use of additives more complex.

    “due to the particularities of air travel, specification regarding approval and use of additives is more complex”
4 of 4

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

Cites

Flagged first, then by citations

1 of the 41 references couldn’t be matched to a known paper.

Research works printed but not linked: 4

  1. United Nations (December, January 30). Framework Convention on Climate Change. Adoption of the Paris Agreement. Proceedings of the 21st Conference of the Parties, Paris, France.
  2. United Nations (November, January 31). International Aviation Climate Ambition Coalition. Proceedings of the 26th United Nations Climate Change Conference, Glasgow, UK.
  3. Chevron (2007). Aviation Fuels: Technical Review, Chevron.
  4. Roberts, W.L. (2008, January 7). Bio jet fuels. Proceedings of the 5th International Biofuels Conference, New Delhi, India.

Cited by

Sorted by citations

Related

Authors
Cabrera, E., & de Sousa, J. M. M.
Affiliations
  • Instituto Superior Técnico (PT)
  • IDMEC, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
ORCID
Venue
Energies
Publisher
MDPI AG
Published
2022-03-26
Volume
15
Issue
7
Pages
2440
ISSN
1996-1073 (ISSN-L)
DOI
10.3390/en15072440
OpenAlex
W4221122404
Cited by
217
References
41
Citations by year
2026: 51 · 2025: 67 · 2024: 54 · 2023: 36 · 2022: 8 · 2021: 1
FWCI
16.44
Type
journal article
Language
en
Open access
Licence
Locations
  • Energies (publishedVersion, cc-by)
  • RePEc: Research Papers in Economics (submittedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
Funders
Fundação para a Ciência e Tecnologia (UIDB/50022/2020)
Topics
  • Physical Sciences › Environmental Science › Global and Planetary Change › Advanced Aircraft Design and Technologies
  • Physical Sciences › Engineering › Computational Mechanics › Heat transfer and supercritical fluids
  • Social Sciences › Economics, Econometrics and Finance › General Economics, Econometrics and Finance › Aviation Industry Analysis and Trends
Keywords
sustainable aviation fuel, biofuels, synthetic fuels, hydrogen aviation, aircraft emissions reduction, technology readiness, fossil fuel dependence

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-10.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-10.

Statistics and arithmetic are recomputed, not judged.

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