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Cited by 224Biofuel production and bioconversionBioeconomy and Sustainability DevelopmentMicrobial Metabolic Engineering and Bioproduction

The potential of biofuels from first to fourth generation

Open access
Cavelius, Philipp, Engelhart-Straub, Selina, Mehlmer, Norbert, Lercher, Johannes, Awad, Dania, Brück, Thomas·2023·PLOS Biology
DOI 10.1371/journal.pbio.3002063PMC PMC10063169
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Abstract

The steady increase in human population and a rising standard of living heighten global demand for energy. Fossil fuels account for more than three-quarters of energy production, releasing enormous amounts of carbon dioxide (CO 2) that drive climate change effects as well as contributing to severe air pollution in many countries. Hence, drastic reduction of CO 2 emissions, especially from fossil fuels, is essential to tackle anthropogenic climate change. To reduce CO 2 emissions and to cope with the ever-growing demand for energy, it is essential to develop renewable energy sources, of which biofuels will form an important contribution. In this Essay, liquid biofuels from first to fourth generation are discussed in detail alongside their industrial development and policy implications, with a focus on the transport sector as a complementary solution to other environmentally friendly technologies, such as electric cars.

AI snapshot

Written from the paper’s full text.

TL;DR

This Essay reviews liquid biofuels from first to fourth generation, comparing feedstocks, conversion platforms, fuel properties, industrial deployment, and EU policy. It argues that biofuels are an essential but partial climate solution for transport, requiring stable long-term policy, capital, and technology transfer from pilot to industrial scale.

Key findings

  • Fossil fuels account for around 80% of world energy demand and roughly 89% of total GHG emissions in 2020; petroleum shortage is predicted by 2070 to 2080, while global biofuel demand is set to grow by 41 to 53 billion liters, or 28%, over 2021 to 2026.
  • First-generation biofuels rely on edible feedstocks and raise food-versus-fuel and land-use concerns; second-generation biofuels use lignocellulosic and waste streams, represented about 96% of commercial production in 2019 versus 4% for first generation, and could supply up to 30% of the world’s transportation energy.
  • Third-generation biofuels from microalgae and cyanobacteria show 2- to 4-fold higher photosynthesis rates than terrestrial plants and can use waste, brackish, or salt water; in 2021, 447 algae and cyanobacteria Spirulina production units were mapped in the EU, but most biomass went to food and feed rather than biofuels.
  • Fourth-generation biofuels use genetic engineering, random mutagenesis, and experimental electrobiofuels; cyanobacterial ethanol titers reached up to 5.5 g/L and 1-butanol reached 300 mg/L, while policy recommendations include stable long-term frameworks, CO2 prices of 500 to 1,000 Euros/ton CO2, and RED II targets of 32% renewable energy and at least 14% renewable transport with a minimum 3.5% advanced biofuels.

Methods

  • Design: This is an Essay/review, not a primary research study; it compares first- through fourth-generation liquid biofuels and focuses on EU-centered industrial development and policy.
  • Data or sample: No experimental sample is reported; the text synthesizes cited literature, industrial examples such as Clariant’s sunliquid and LanzaTech, and EU legislation including RED and RED II.
  • Main analysis: Narrative comparative synthesis of feedstocks, fuel properties, commercial status, and policy recommendations; no statistical or systematic review methods are reported.

Limitations

  • Stated: the authors note that their policy recommendations are EU-centric, although many are also applicable globally.
  • Evident: the paper has no formal limitations section and, as an Essay/opinion piece, lacks systematic search or selection criteria and primary data.
  • Evident: industrial, economic, and policy figures rely on cited reports and company estimates and may be time-sensitive; no quantitative uncertainty analysis is provided.

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

Integrity signals

Registry

Crossref · 10.1371/journal.pbio.3002063

Cites

87 of 87 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

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  • Premisecitation

    Petroleum shortage is predicted by 2070 to 2080.

    “estimations predict a shortage by 2070 to 2080 [4]”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [4] S Sharma, 2020, Sustainable environmental management and related biofuel technologies, J Environ Manage source

      Not checked in the free run.

  • Premisecitation

    Closed photobioreactors allow precise control of process parameters, often leading to higher productivity.

    “The alternative, preferred for high price, low volume products, such as cosmetic ingredients, is a closed photobioreactor, where process parameters can be precisely controlled, which often leads to higher productivity [63,68].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [63] F Melcher, 2021, 9 Photosynthetic conversion of CO2 into bioenergy and materials using microalgae., Photosynthesis. source

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    • cites [68] JM Neto, 2019, Third generation biofuels: an overview., Sustainable Bioenergy. source

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  • Premisecitation

    Fargione and colleagues estimated it would take 319 years to repay the biofuel carbon debt resulting from clearing tropical rainforest in Brazil and subsequent conversion to soybean plantations.

    “In 2008, Fargione and colleagues estimated that it would take 319 years to repay the biofuel carbon debt resulting from clearing of tropical rainforest in Brazil and subsequent conversion to soybean plantations [40].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [40] J Fargione, 2008, Land clearing and the biofuel carbon debt, Science source

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  • Premisecitation

    In conventional algae cultivation systems, around 70% of supplied CO2 is used for photosynthesis and therefore biomass production.

    “In conventional cultivation systems, around 70% of supplied CO2 is used for photosynthesis and therefore biomass production [65].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [65] J Doucha, 2006, Productivity, CO2/O2 exchange and hydraulics in outdoor open high density microalgal (Chlorella sp.) photobioreactors operated in a Middle and Southern European climate, J Appl Phycol source

      Not checked in the free run.

  • Interpretationreasoning

    Second-generation biofuels by themselves will not be sufficient to supply energy for the current worldwide demand.

    “Despite the highly favorable ability to valorize waste streams, second-generation biofuels by themselves will not be sufficient to supply energy for the current worldwide demand.”
    Quote in the paperSubstantial claim
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    Premisecitation

    Fossil fuels represented roughly 89% of total greenhouse gas emissions in 2020.

    “representing roughly 89% of total greenhouse gas (GHG) emissions in 2020 [3]”
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    • cites [3] JGJ Olivier, 2020, Trends in global CO2 and total greenhouse gas emissions: 2020 report., PBL Netherlands Environmental Assessment Agency, The Hague.

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    Premisecitation

    Biofuels emit less greenhouse gases and are generally more eco-friendly (non-toxic, sulfur-free, biodegradable) than fossil fuels.

    “Biofuels emit less GHGs and are in general more eco-friendly (non-toxic, sulfur-free, biodegradable) than their fossil fuel predecessors [5].”
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    • cites [5] SJ Malode, 2021, Recent advances and viability in biofuel production, Energy Conversion and Management: X

      Not checked in the free run.

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    Premisecitation

    Global demand for biofuels is set to grow by 41 to 53 billion liters, or 28%, over 2021 to 2026.

    “Global demand for biofuels is set to grow by 41 to 53 billion liters, or 28%, over 2021 to 2026 [7].”
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    • cites [7] IEA., 2021

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    Premisecitation

    Fossil fuels account for around 80% of the world's energy demand.

    “To date, fossil fuels account for around 80% of the world’s energy demand [2]”
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    • cites [2] F Johnsson, 2018, The threat to climate change mitigation posed by the abundance of fossil fuels., Climate Policy source

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    Premisecitation

    Biofuels of first and second generation were commercially produced around 4% and 96% in 2019, respectively.

    “For the most part, biofuels of the first and in the vast majority of the second generation are commercially produced, around 4% and 96% in 2019, respectively [44].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [44] B Abdullah, 2019, Fourth generation biofuel: A review on risks and mitigation strategies., Renew Sustain Energy Rev source

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    Premisecitation

    Algae exhibit 2- to 4-fold higher photosynthesis rates than terrestrial plants, resulting in faster biomass formation.

    “Algae exhibit 2- to 4-fold higher photosynthesis rates than terrestrial plants, resulting in faster biomass formation [62].”
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    • cites [62] Y Li, 2008, Biofuels from microalgae, Biotechnol Prog source

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    Premisecitation

    Most algae/cyanobacteria production companies in the EU directed their biomass to food, feed, and related uses; commercial application of biofuels only had a very small share.

    “Most of these companies directed their biomass to the production of food, feed, and related uses; commercial application of biofuels only had a very small share.”
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    • cites [70] R Araújo, 2021, Current Status of the Algae Production Industry in Europe: An Emerging Sector of the Blue Bioeconomy., Front Mar Sci source

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    Premisecitation

    Biobutanol production on lignocellulose biomass and other waste streams is most commonly based on Clostridia fermentation, but is limited by low butanol titers and product inhibition.

    “However, similar to its first-generation predecessor, the process is limited by low butanol titers and product inhibition [11,16,18,38].”
    Quote in the paperNot a substantial claim0 of 4 sources checked
    • cites [11] R Sindhu, 2019, Biofuel Production From Biomass, Current Developments in Biotechnology and Bioengineering source

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    • cites [16] K Vamsi Krishna, 2022, An updated review on advancement in fermentative production strategies for biobutanol using Clostridium spp., Environ Sci Pollut Res Int source

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    • cites [18] C Karthick, 2021, A comprehensive review on ecological approaches of waste to wealth strategies for production of sustainable biobutanol and its suitability in automotive applications., Energ Conver Manage. source

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    • cites [38] Y Jiang, 2019, Current status and perspectives on biobutanol production using lignocellulosic feedstocks, Bioresour Technol Rep

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    Premisecitation

    Since 2022, a demonstration plant in Japan has turned municipal solid waste to ethanol, with a production target of 20 tons of ethanol per day.

    “Since 2022, a demonstration plant in Japan has turned municipal solid waste to ethanol, with a production target of 20 tons of ethanol per day [60].”
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    • cites [60] LanzaTech, 2022, New Waste-to-Ethanol Facility in Japan Turns Municipal Solid Waste into Products.

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

    Interpretationreasoning

    Second-generation biofuels circumvent the need for agricultural land use change and do not compete with food resources.

    “Hence, second-generation biofuels circumvent the need for agricultural land use change and do not compete with food resources.”
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    Premisecitation

    Second-generation waste streams often represent more complex feedstocks than sugarcane or palm oil, potentially containing compounds able to reduce fermentation efficiency, such as lignin.

    “However, often second-generation waste streams represent more complex feedstocks than sugarcane or palm oil, potentially containing compounds able to reduce fermentation efficiency, such as lignin.”
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    • cites [5] SJ Malode, 2021, Recent advances and viability in biofuel production, Energy Conversion and Management: X

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    • cites [42] W Mischko, 2018, Modular biomanufacturing for a sustainable production of terpenoid-based insect deterrents, Green Chem source

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    • cites [43] G Joshi, 2017, Challenges and opportunities for the application of biofuel., Renew Sustain Energy Rev source

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    Interpretationreasoning

    Algal-based oil production is likely greater than that in higher plants, as lipids mainly accumulate in specific parts of the plant while in algae each cell can contain high amount of lipids, making the process more mass efficient.

    “Additionally, algal-based oil production is likely greater than that in higher plants, as lipids mainly accumulate in specific parts of the plant (e.g., in rape seeds), while in algae, each cell can contain high amount of lipids, making the process more mass efficient.”
    Quote in the paperSubstantial claim

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    Premisecitation

    Syngas fermentation has advantages over other second-generation approaches: high feedstock flexibility and high rates of energy and carbon capture.

    “Advantages of syngas fermentation compared to other second-generation approaches are high feedstock flexibility as well as high rates of energy and carbon capture.”
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    • cites [58] J Daniell, 2012, Commercial Biomass Syngas Fermentation., Energies source

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    Premisecitation

    Open pond reactors are significantly cheaper in construction and operation but have drawbacks like high water loss through evaporation and lack of temperature control, which lowers biomass productivity.

    “Open pond reactors are significantly cheaper in their construction and operation but have drawbacks like high loss of water through evaporation and lack of temperature control, which lowers biomass productivity.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [63] F Melcher, 2021, 9 Photosynthetic conversion of CO2 into bioenergy and materials using microalgae., Photosynthesis. source

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    • cites [68] JM Neto, 2019, Third generation biofuels: an overview., Sustainable Bioenergy. source

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    Premisecitation

    Application of additional pretreatment steps for second-generation feedstocks is common, increasing process time and costs.

    “Therefore, application of additional pretreatment steps are common, increasing process time and costs [5,42,43].”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [5] SJ Malode, 2021, Recent advances and viability in biofuel production, Energy Conversion and Management: X

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    • cites [42] W Mischko, 2018, Modular biomanufacturing for a sustainable production of terpenoid-based insect deterrents, Green Chem source

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    • cites [43] G Joshi, 2017, Challenges and opportunities for the application of biofuel., Renew Sustain Energy Rev source

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

    Premisecitation

    Araújo and colleagues mapped 447 algae and cyanobacteria Spirulina production units in 2021 in the EU.

    “Araújo and colleagues mapped 447 algae and cyanobacteria Spirulina production units in 2021 in the EU [70].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [70] R Araújo, 2021, Current Status of the Algae Production Industry in Europe: An Emerging Sector of the Blue Bioeconomy., Front Mar Sci source

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    Premisecitation

    LanzaTech estimates a total product capacity of 600,000 metric tons and 1,000,000 metric tons of captured carbon per year for all their plants combined.

    “They estimate a total product capacity of 600,000 metric tons as well as 1,000,000 metric tons of captured carbon per year, for all their plants combined [59].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [59] LanzaTech. Annual Report 2021. 2021. Available from: https://lanzatech.com/wp-content/uploads/2022/08/LanzaTech_2021_Annual_Report.pdf.

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    Premisecitation

    Algae do not require arable land or fresh water for cultivation; many cultures can be grown using waste water, brackish or salt water.

    “Algae do not require arable land or fresh water for cultivation. Many cultures can be grown using waste water, brackish or salt water, which is cost efficient and circumvents competition with agricultural activity [63,64].”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [63] F Melcher, 2021, 9 Photosynthetic conversion of CO2 into bioenergy and materials using microalgae., Photosynthesis. source

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    • cites [64] MA Borowitzka, 2010, Sustainable biofuels from algae, Mitig Adapt Strat Glob Chang source

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    Premisecitation

    Cutaneotrichosporon oleaginosus yeast is capable of producing up to 90% (w/w) lipids per biomass in a fermentation process, and can be grown on residue streams.

    “the production of second-generation biodiesel is possible from microbial lipids produced by organisms, such as Cutaneotrichosporon oleaginosus, a yeast capable of producing up to 90% (w/w) lipids per biomass in a fermentation process, which can be grown on residue streams (e.g., wheat bran hydrolysate medium) [46–49].”
    Quote in the paperNot a substantial claim0 of 4 sources checked
    • cites [46] T Fuchs, 2021, Identifying carbohydrate-active enzymes of Cutaneotrichosporon oleaginosus using systems biology, Microb Cell Fact source

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    • cites [47] P Shaigani, 2021, Oleaginous yeasts- substrate preference and lipid productivity: a view on the performance of microbial lipid producers, Microb Cell Fact source

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    • cites [48] MA Masri, 2019, A sustainable, high-performance process for the economic production of waste-free microbial oils that can replace plant-based equivalents., Energ Environ Sci source

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    • cites [49] S Younes, 2020, Microbial lipid production by oleaginous yeasts grown on Scenedesmus obtusiusculus microalgae biomass hydrolysate., Bioprocess Biosyst Eng source

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

    Premisecitation

    RED II aims to increase the share of renewable energy to 32% and in transport to at least 14%, including a minimum share of 3.5% of advanced biofuels (second- and third-generation biofuels).

    “Therewith, the EU aims to increase the share of renewable energy to 32% and in transport to at least 14%, including a minimum share of 3.5% of advanced biofuels (second- and third-generation biofuels).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [95] The International Council on Clean Transportation, 2018, FINAL RECAST RENEWABLE ENERGY DIRECTIVE FOR 2021–2030 IN THE EUROPEAN UNION

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    Premisecitation

    A European-based study concluded that genetically engineered algae for biofuel production would be accepted by the majority of consumers when the safety of the systems can be guaranteed.

    “A European-based study came to the conclusion that genetically engineered algae for biofuel production would be accepted by the majority of consumers, when the safety of the systems can be guaranteed [80].”
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    • cites [80] J Varela Villarreal, 2020, Acceptability of genetically engineered algae biofuels in Europe: opinions of experts and stakeholders, Biotechnol Biofuels source

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    Premisecitation

    Transportation contributes about 17% of global CO2 emissions.

    “It contributes about 17% of global CO2 emissions [85,86]”
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    • cites [85] Carbon Leadership Forum, 2023, Embodied Carbon 101

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    • cites [86] H Ritchie, 2020, CO2 and Greenhouse Gas Emissions

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    Premisecitation

    1-butanol production reached titers of 300 mg/L, and bioethanol titers of up to 5.5 g/L were reported.

    “While 1-butanol production reached titers of 300 mg/L, bioethanol titers of up to 5.5 g/L were reported [77–79].”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [77] NK Mund, 2022, Advances in metabolic engineering of cyanobacteria for production of biofuels, Fuel

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    • cites [78] Z Zahra, 2020, Cyanobacteria: Review of Current Potentials and Applications., Environments source

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    • cites [79] X Liu, 2019, Modular engineering for efficient photosynthetic biosynthesis of 1-butanol from CO2in cyanobacteria., Energ Environ Sci source

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    Premisecitation

    Bioleaching or biomining employs microbes such as Acidithiobacillus ferrooxidans that can bind and recover metals, bypassing the need for high temperatures and toxic chemicals.

    “One alternative is bioleaching or biomining, which employs microbes such as Acidithiobacillus ferrooxidans that can bind and recover metals, bypassing the need for high temperatures and toxic chemicals [87–90].”
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    • cites [87] D Mishra, 2008, Bioleaching of metals from spent lithium ion secondary batteries using Acidithiobacillus ferrooxidans., Waste Manag. source

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    • cites [88] JJ Roy, 2021, A review on the recycling of spent lithium-ion batteries (LIBs) by the bioleaching approach, Epub 20210521

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    • cites [89] Y Xin, 2016, Bioleaching of valuable metals Li, Co, Ni and Mn from spent electric vehicle Li-ion batteries for the purpose of recovery., J Clean Prod. source

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    • cites [90] W Jurkowski, 2022, Isolation and Investigation of Natural Rare Earth Metal Chelating Agents From Calothrix brevissima—A Step Towards Unraveling the Mechanisms of Metal Biosorption., Front Bioeng Biotechnol. source

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    Premisecitation

    Overexpression of transporters is challenging as it modifies membrane composition, creating a metabolic burden and potentially overloading cellular import/export, thereby disabling homeostasis.

    “However, the overexpression of transporters is challenging as it modifies the membrane composition, creating a metabolic burden as well as potentially overloading the cellular import and export, thereby disabling the cells ability to regulate its internal environment/homeostasis [71].”
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    • cites [71] S Malik, 2021, Developing fourth-generation biofuels secreting microbial cell factories for enhanced productivity and efficient product recovery; a review., Fuel. source

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    Premisecitation

    The EU's major trading partners are Argentina, Brazil, USA, Indonesia, and Malaysia.

    “Currently, the major trading partners of the EU are Argentina, Brazil, USA, Indonesia, and Malaysia [97].”
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    • cites [97] European Commission, 2012, Indirect Land Use Change (ILUC)

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    Premisecitation

    ILUC qualifies first-generation biofuels based on the unintended consequences of releasing carbon emissions as a result of land use changes.

    “ILUC qualifies first-generation biofuels based on the unintended consequences of releasing carbon emissions as a result of land use changes [96,97].”
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    • cites [96] SC Bhatia, 2014, Issues relating to biofuels., Advanced Renewable Energy Systems. source

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    • cites [97] European Commission, 2012, Indirect Land Use Change (ILUC)

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

    Interpretationreasoning

    A combination of synthetic and biofuels in synergy with electric cars might be an optimal solution for the years to come, partially substituting fossil fuels, thereby drastically reducing CO2 output of transportation.

    “To that point, a combination of synthetic and biofuels in synergy with electric cars might be an optimal solution for the years to come, partially substituting fossil fuels, thereby drastically reducing CO2 output of transportation.”
    Quote in the paperNot a substantial claim

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

    Premisecitation

    Deployment of renewable energy has continuously grown, exceeding 22% in 2020.

    “It is noteworthy that the deployment of renewable energy has continuously grown, exceeding 22% in 2020 [92].”
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    • cites [92] European Commission, 2023, Renewable energy directive

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    Premisecitation

    68% of the world population is projected to live in urban areas by 2050.

    “68% of the world population is projected to live in urban areas by 2050”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [102] United Nations—Department of Economic and Social Affairs, 2018, 68% of the world population projected to live in urban areas by 2050, says UN.

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  • May combine two claims.

    Premisecitation

    Most industrialized EU countries with high population density do not have sufficient land or biomass availability for large-scale biofuel production, unlike Nordic countries.

    “Contrary to Nordic countries that are the forefront of advanced biofuel processes development, most industrialized countries in the EU with a high population density do not have sufficient land or biomass availability for large-scale biofuel production [100].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [100] BAC-TO-FUEL, 2023, RED II: The renewable Energy Directive

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  • May combine two claims.

    Interpretationreasoning

    Current technologies for biofuels are not likely to completely replace fossil fuels in their entirety but can offer new routes for waste stream valorization in a circular economy and contribute significantly to minimize dependency on fossil fuels.

    “Due to their limitations, current technologies for biofuels are not likely to completely replace fossil fuels in their entirety but can offer new routes for waste stream valorization in a circular economy and contribute significantly to minimize our dependency on fossil fuels one step at a time.”
    Quote in the paperSubstantial claim

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

    Premisecitation

    The EU Renewable Energy Directive (RED) came into force in 2009 and set targets for renewable energy consumption, including a subtarget mandating 10% of energy used in transport to be produced from renewables.

    “Most notable is the Renewable Energy Directive (RED), which came into force in 2009. Through this directive, EU countries set targets for renewable energy consumption, including a subtarget mandating 10% of energy used in transport to be produced from renewables.”
    Quote in the paperNot a substantial claim0 of 4 sources checked
    • cites [91] IRENA International Renewable Energy Agency, 2023, About IRENA

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    • cites [92] European Commission, 2023, Renewable energy directive

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    • cites [93] European Environment Agency. 19.01.2023. Available from: https://www.eea.europa.eu/.

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    • cites [94] IPCC—The Intergovernmental Panel on Climate Change, 2022, Climate Change 2022: Mitigation of Climate Change.

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  • May combine two claims.

    Premisecitation

    Limiting EU countries' demand for palm oil biofuels could avoid 130,000 to 210,000 hectares of deforestation, which has detrimental effects on biodiversity and soil quality.

    “Reports estimate that 130,000 to 210,000 hectares of deforestation, which has detrimental effect on biodiversity and soil quality, could be avoided by limiting the demand of EU countries for palm oil biofuels [98].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [98] Transport & Environment, 2019, High & low ILUC risk biofuels Policy recommendations for the EU delegated act

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

    Interpretationreasoning

    The fundamental transition toward sustainable bio-based technologies will require long-sighted, fact-driven legislative guidance and immense capital investments across the private and governmental sectors.

    “This fundamental transition toward sustainable bio-based technologies will require long-sighted, fact-driven legislative guidance and immense capital investments across the private and governmental sectors.”
    Quote in the paperNot a substantial claim

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

    Interpretationnone given

    Once production with a base process has commenced, these processes can be iteratively refined or modulated at scale to evolve toward the next technology generation.

    “Once production with a base process has commenced, these processes can be iteratively refined or modulated at scale to evolve toward the next technology generation.”
    Quote in the paperNot a substantial claim

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

    Interpretationreasoning

    EU-level funding measures do not translate into national actions and legislation on a member state level, which impedes regional mobilization of capital and leads to slow uptake and implementation of new technologies.

    “these measures do not translate into national actions and legislation on a member state level, which impedes the regional mobilization of capital, leading to a slow uptake and implementation of new technologies.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: On an EU level, specific funding mechanisms such as European Innovation Council (EIC) pathfinder, EIC Transition, and EIC Accelerator already exist.
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  • The paper relies on this without support.

    Increased market values of palm oil and other biofuel cultures prompted extended deforestation of tropical rainforests for biofuel crop plantations, which releases more CO2 than the emission saved by those biofuels.

    “Furthermore, increased market values of palm oil and other biofuel cultures prompted extended deforestation of tropical rainforests for biofuel crop plantations, which releases more CO2 than the emission saved by those biofuels.”

  • The paper relies on this without support.

    More than half of biologically stored carbon is bound in marine biomass, especially macroalgae and seagrass.

    “More than half of the biologically stored carbon is bound in marine biomass, especially macroalgae and seagrass.”

  • The paper relies on this without support.

    For most native producers of biofuels, the genetic engineering toolbox is far more limited than for model organisms.

    “Unfortunately, for most native producers of biofuels, the genetic engineering toolbox is far more limited.”

  • The paper relies on this without support.

    Random mutagenesis can be performed with little knowledge about the production organism and production pathway.

    “Furthermore, this technique can be performed with little knowledge about the production organism and production pathway.”

  • The paper relies on this without support.

    Biofuel production requires more processing steps compared with conventional methods of drilling and refining.

    “However, to fully exploit all the positive traits of biofuels, further research and investments are necessary, as the production of biofuels requires more processing steps compared with the conventional methods of drilling into the ground to obtain crude oil, followed by refining.”

  • The paper relies on this without support.

    Raw materials for biofuel production do not compare to crude oil in energy density, requiring far greater amounts of biomass for the same energy output compared to fossil sources.

    “Furthermore, raw materials for biofuel production do not compare to crude oil in energy density, requiring far greater amounts of biomass for the same energy output compared to fossil sources.”

  • The paper relies on this without support.

    At present, industrial biofuel production is dominated by first- and second-generation processes.

    “At present, the industrial biofuel production is dominated by first- and second-generation processes, respectively.”

  • The paper relies on this without support.

    While technical process development for third- and fourth-generation biofuels is advancing rapidly in academic and start-up settings, large-scale industrial implementation remains lagging.

    “While technical process development for third- and fourth-generation biofuels is advancing rapidly in academic and start-up settings, large-scale industrial implementation remains lagging.”

  • The paper relies on this without support.

    In the past, one of the greatest barriers for industry to adopt new biofuel technologies in the EU was the constantly changing regulatory and provisions framework, which led to waves of market and company consolidation for first-generation fuels.

    “In the past, one of the greatest barriers for industry to adopt new biofuel technologies, at least in the EU, was the constantly changing regulatory and provisions framework, which ultimately led to waves of market and company consolidation for first-generation fuels such as crop-based biodiesel, corn and sugar beet-based bioethanol, and, more recently, corn-based biogas products.”

  • The paper relies on this without support.

    The implementation of industrial biofuel production sites is associated with immense capital investments.

    “As the implementation of industrial biofuel production sites are associated with immense capital investments, it is crucial to shed light on the financial aspect linked to these policies”

  • The paper relies on this without support.

    Technology development from proof of concept (TRL 2 to 4) in academic settings to pilot plant level often requires time periods exceeding 5 to 7 years.

    “As technology development from proof of concept (TRL 2 to 4) in academic settings to pilot plant level often requires time periods exceeding 5 to 7 years, synergistic midterm private funding resources also have to be mobilized.”

  • The paper relies on this without support.

    Legislatively guided de-risking of capital investment into new technologies is already implemented in the United States of America and the United Kingdom, as well as in other, less compliance-driven, financial markets.

    “This legislatively guided de-risking of capital investment into new technologies is already implemented in the United States of America and the United Kingdom, as well as in other, less compliance-driven, financial markets.”

  • The paper relies on this without support.

    Capital is short at the infrastructure and logistics level.

    “Capital is also short at the infrastructure and logistics level.”

  • The paper relies on this without support.

    There is little information on correlative carbon storage, which is mostly limited to terrestrial biomass, while there is a good overview of regional carbon emissions.

    “While we have a good overview of regional carbon emissions, there is little information on correlative carbon storage, which is mostly limited to terrestrial biomass.”

  • The paper relies on this without support.

    People outside scientific communities are ready to accept change of the status quo in order to curb climate change effects and transition to a sustainable society.

    “Even outside the scientific communities, people are ready to accept change of the status quo in order to curb climate change effects and transition to a sustainable society.”

  • The paper relies on this without support.

    The EU's major trading partners' practices do not ensure level field sustainability over the long term.

    “These trading practices do not ensure level field sustainability over the long term.”

  • The paper relies on this without support.

    On an EU level, specific funding mechanisms such as European Innovation Council (EIC) pathfinder, EIC Transition, and EIC Accelerator already exist.

    “On an EU level, specific funding mechanisms such as European Innovation Council (EIC) pathfinder, EIC Transition, and EIC Accelerator that aim to enable and accelerate the scaling trajectory of new technologies toward market entry already exist.”

  • The paper relies on this without support.

    Two routes for biofuels production are viable in the EU: a large production plant located in a region with abundant, long-term feedstock/biomass supply or secured trade routes; or a network of smaller, decentralized production facilities.

    “Two routes for biofuels production are viable in the EU: a large production plant located in a region with abundant, long-term feedstock/biomass supply or secured trade routes; or a network of smaller, decentralized production facilities.”

  • The paper relies on this without support.

    The implementation of biofuels in industrial processes requires a secured feedstock supply.

    “In parallel to technology market readiness, the implementation of biofuels in industrial processes requires a secured feedstock supply.”
19 of 19

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?

  • Fifth-generation biofuels represent a conceptual frontier beyond fourth-generation advancements and remain largely conceptual, often characterized by the integration of synthetic biology, potentially nanotechnology, and novel process designs like electro-biofuel or direct solar fuel production using highly engineered organisms to overcome fundamental efficiency, cost, and feedstock limitations,虽然尚

    “Fifth-generation (5-G) biofuels represent a conceptual frontier beyond fourth-generation advancements and remain largely conceptual, often characterized by the integration of synthetic biology, potentially nanotechnology, and novel process designs like electro-biofuel or direct solar fuel production using highly engineered organisms to overcome fundamental efficiency, cost, and feedstock”

    From Biofuels, E-Fuels, and Waste-Derived Fuels: Advances, Challenges, and Future Directions (2025) · cites this paper as [170]

    Split into 2 atoms — 0 confirmed, 0 partially supported, 2 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

    Checked by a reasoning model — may be wrong.

    Experimental — accuracy not yet measured

  • Anticipated advantages of 5-G biofuels center on potentially achieving superior energy conversion efficiencies, utilizing ubiquitous feedstocks like CO2 and sunlight thereby minimizing land and water resource competition, and offering pathways towards truly carbon-neutral or even carbon-negative fuel cycles.

    “Anticipated advantages center on potentially achieving superior energy conversion efficiencies, utilizing ubiquitous feedstocks like CO 2 and sunlight thereby minimizing land and water resource competition, and offering pathways towards truly carbon-neutral or even carbon-negative fuel cycles [170].”

    From Biofuels, E-Fuels, and Waste-Derived Fuels: Advances, Challenges, and Future Directions (2025) · cites this paper as [170]

    Split into 2 atoms — 0 confirmed, 2 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

    Experimental — accuracy not yet measured

  • Earlier biofuel generations, particularly 1-G, faced significant resource-related criticism regarding competition with food production and extensive land and water use, sometimes leading to negative ILUC impacts like deforestation.

    “This contrasts sharply with earlier biofuel generations, particularly 1-G, which faced significant resource-related criticism regarding competition with food production and extensive land and water use, sometimes leading to negative ILUC impacts like deforestation [170].”

    From Biofuels, E-Fuels, and Waste-Derived Fuels: Advances, Challenges, and Future Directions (2025) · cites this paper as [170]

    The First-generation biofuels section (page not provided) describes the food-versus-fuel debate, large land requirements, and deforestation associated with biofuel crop plantations. The EU policy recommendations section discusses freshwater use as a consideration for biofuels generally, but does not establish extensive water use as a specific criticism of first-generation biofuels. (LLM, conf=0.86)

    Experimental — accuracy not yet measured

  • Realizing the potential of third-generation (algae-based) and fourth-generation (genetically engineered organisms) bioenergy necessitates critical advancements in harvesting techniques, downstream processing efficiency, cost reduction, and managing public acceptance and safety concerns related to genetic modification.

    “Realizing the potential of 3-G (algae-based) and 4-G (genetically engineered organisms) bioenergy necessitates critical advancements in harvesting techniques (especially for microalgae), downstream processing efficiency, cost reduction, and managing public acceptance and safety concerns related to genetic modification [170,173].”

    From Biofuels, E-Fuels, and Waste-Derived Fuels: Advances, Challenges, and Future Directions (2025) · cites this paper as [170]

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

  • Biodiesel fuel equivalence conflicts with listed heating values

    Minor

    Table 1 gives biodiesel and gasoline heating values of 32.65 and 32.48 MJ/L. Using gasoline as the table's 1 L reference gives biodiesel a fuel equivalence of about 1.005, rather than the reported 0.91.

    Reported 0.91 · recomputed 1.005234

1 of 1

Cites

Flagged first, then by citations

Research works printed but not linked: 14

  1. PJ Jørgensen, 2023, Biogas—Green_Energy
  2. FNR Fachagentur Nachwachsende Rohstoffe e.V., 2019, BIOENERGY IN GERMANY FACTS AND FIGURES 2020
  3. AP Daniel Trost, 2020, Mathematical models for temperature dependent viscosity of biobutanol and gasoline blends., MendelNet., 27, 486
  4. S. Katemann, 2023, Was kostet eine Biogasanlage?, Mit diesen Kosten sollten Sie rechnen
  5. Chemanalyst, 2023, n-Butanol Price Trend and Forecast
  6. Neste, 2023, Biodiesel prices (SME & FAME)
  7. fuel-prices.eu, 2023, Fuel prices in Europe: Diesel (B7), Petrol (E5) & LPG
  8. LanzaTech, 2022, New Waste-to-Ethanol Facility in Japan Turns Municipal Solid Waste into Products.
  9. Carbon Leadership Forum, 2023, Embodied Carbon 101
  10. H Ritchie, 2020, CO2 and Greenhouse Gas Emissions
  11. The International Council on Clean Transportation, 2018, FINAL RECAST RENEWABLE ENERGY DIRECTIVE FOR 2021–2030 IN THE EUROPEAN UNION
  12. European Commission, 2012, Indirect Land Use Change (ILUC)
  13. Bundesministerium für Wirtschaft und Klimatschutz, 2023, EXIST-Gründerstipendium Das Programm in Kürze
  14. OECD, 2023, Promoting Technological Innovation to Address Climate Change.

Cited by

Sorted by citations

Related

Authors
Cavelius, P., Engelhart-Straub, S., Mehlmer, N., Lercher, J., Awad, D., & Brück, T.
Affiliations
Technical University of Munich (DE)
Corresponding author
  • Awad, Dania
  • Brück, Thomas
ORCID
Venue
PLOS Biology
Publisher
Public Library of Science (PLoS)
Published
2023-03-30
Volume
21
Issue
3
Pages
e3002063
ISSN
  • 1544-9173 (ISSN-L)
  • 1545-7885
DOI
10.1371/journal.pbio.3002063
PMC
PMC10063169
OpenAlex
W4361255782
Semantic Scholar
096e049284a45a389750f678cd082cb3b460533e
Cited by
224
References
87
Citations by year
2026: 62 · 2025: 93 · 2024: 58 · 2023: 11
FWCI
17.69
Type
journal article
Language
en
Open access
Licence
Locations
  • PLoS Biology (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
Funders
Bundesministerium für Bildung und Forschung (031B0853A)
Topics
  • Physical Sciences › Engineering › Biomedical Engineering › Biofuel production and bioconversion
  • Life Sciences › Agricultural and Biological Sciences › General Agricultural and Biological Sciences › Bioeconomy and Sustainability Development
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Microbial Metabolic Engineering and Bioproduction
Keywords
biofuels, first-generation biofuels, second-generation biofuels, third-generation biofuels, fourth-generation biofuels, renewable energy, CO2 emission reduction, climate change mitigation, fossil fuel dependence, biofuel policy, transport sector, liquid biofuels
MeSH terms
Air Pollution, Carbon Dioxide, Fossil Fuels, Humans, Biofuels, Climate Change

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.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

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