Plant Biomass as Biofuels


Sustainable and renewable fuel sources are imperative to maintain future global commerce, mobility and economic prosperity, to alleviate current dependency on fossil fuels and to mitigate greenhouse gas emissions from combustion in vehicles. Plant biomass and its derivatives represent an abundant carbon source for the production of biobased alternatives to petroleum‐based transport fuel. The production of first‐generation biofuels is currently the most advanced, with bioethanol being manufactured commercially in many countries. However, the major disadvantage of first‐generation biofuels is that they introduce competition for land on which human food crops are grown. Second‐generation biofuels from lignocellulose address this issue, but their production is not yet fully commercial. Advanced biofuels from algae are an alternative biofuel technology currently in the early stages of development. Minimising renewable plant biomass feedstock cost, improving biomass feedstock yields, establishing efficient, coordinated processes for carbon neutral commercial production and changing policy in favour of developing existing and future biofuel technologies are some of the challenges that must be overcome before biofuels can become competitive with fossil fuels.

Key Concepts

  • Global prosperity is closely linked to transport of goods and people; however, for practical, political and environmental reasons, the combustion of fossil fuels is not sustainable. Biofuels offer an alternative that is minimally disruptive to the existing infrastructure at this early stage in the transition towards a biobased economy.
  • Biofuels are mainly derived from plants and are characterised according to the source of the plant material used in their production; ‘first‐generation’ (1G) biofuels (ethanol and biodiesel) are derived from the fermentation of sugar‐ or transesterification of oil‐rich food crops; ‘second‐generation’ (2G) biofuels come from plant biomass that is not suitable for human or animal consumption, such as straw, wood, energy crops or inedible plant oils; ‘advanced biofuels’ are generated by microbes, notably, oleaginous yeasts or microalgae, where the microbe does not convert the substrate to fuel but is the immediate source of the fuel.
  • Advanced biofuels can further be classified as ‘third generation’ if they are made by naturally occurring microbes or ‘fourth generation’ if the biofuels are produced by synthetic biology in engineered microbes.
  • First‐generation ethanol and biodiesel are relatively simple to produce and used in fuel blends throughout the world.
  • Lignocellulose (LC) forms the structure of plant cell walls and is the most abundant natural polymer on the Earth but is very resistant to degradations; to produce 2G ethanol, lignocellulosic biomass must be pretreated to release the sugars, which are then fermented to ethanol.
  • Advanced biofuels are largely at the experimental phase of development.
  • Whatever the source, biofuels face a number of challenges including the cost of the feedstock, the cost of conversion to biofuel and slow progress from laboratory to pilot‐scale production.

Keywords: biofuel; biomass; bioethanol; biodiesel; bioenergy; lignocellulose; first‐generation biofuel; second‐generation biofuel; advanced biofuel

Figure 1. Summary of first‐, second‐ and third‐generation biofuels and the feedstocks from which they are made.
Figure 2. First‐generation ethanol production from glucose and starch. (a) Diagram of the anaerobic conversion of glucose to ethanol by yeast (Saccharomyces cerevisiae) via the action of fermentation. (b) Schematic representation of the principle steps involved in starch hydrolysis (saccharification), before fermentation.
Figure 3. Schematic representation of the transesterification of storage lipid (triacylglycerides) with alcohol to produce biodiesel (fatty acid methyl ester; FAME) and glycerol.
Figure 4. Simplified process flowchart of the production of (a) biogas and (b) syngas.
Figure 5. Schematic representation of lignocellulose. Two molecular groups are shown, representing the structure of cellulose and a potential structure of xylan, one of the components of hemicellulose. Cellulose is composed of repeating units of glucose bound by B‐1,4,glucosidic bonds. Conversely, Xylan contains not only bonds between the xylose monomers but also additional components branching from the main chain.


Adams JMM, Ross AB, Anastasakis K, et al. (2011) Seasonal variation in the chemical composition of the bioenergy feedstock Laminaria digitata for thermochemical conversion. Bioresource Technology 102 (1): 226–234.

Ahmad AL, Mat Yasin NH, Derek CJC and Lim JK (2011) Microalgae as a sustainable energy source for biodiesel production: a review. Renewable and Sustainable Energy Reviews 15 (1): 584–593.

Al‐Abdullah MH, Kalghatgi GT and Babiker H (2015) Flash points and volatility characteristics of gasoline/diesel blends. Fuel 153: 67–69.

Al‐Hasan M (2003) Effect of ethanol–unleaded gasoline blends on engine performance and exhaust emission. Energy Conversion and Management 44 (9): 1547–1561.

Berchmans HJ and Hirata S (2008) Biodiesel production from crude Jatropha curcas L. seed oil with a high content of free fatty acids. Bioresource Technology 99: 1716–1721.

Berlin A, Balakshin M, Gilkes N, et al. (2006) Inhibition of cellulase, xylanase and β‐glucosidase activities by softwood lignin preparations. Journal of Biotechnology 125 (2): 198–209.

Carriquiry MA, Dub X and Timilsina GR (2011) Second generation biofuels: economics and policies. Energy Policy 39: 4222–4234.

Chakravorty U, Hubert M‐H and Nøstbakken L (2009) Fuel versus food. Annual Review of Resource Economics 1 (1): 645–663.

Chisti Y (2007) Biodiesel from microalgae. Biotechnology Advances 25: 294–306.

Cohen Z and Ratledge C (eds) (2002) Single Cell Oils: Microbial and Algal Oils. Urbana, IL: AOCS Press. ISBN: 9781893997738.

Demirbas A (2009) Political, economic and environmental impacts of biofuels: a review. Applied Energy 86: S108–S117.

EASAC (2012) The Current Status of Biofuels in the European Union, their Environmental Impacts and Future Prospects. EASAC policy report 19, ISBN: 978-3-8047-3118-9, ePublication available at:

FAO (2014) FAOSTAT. Food and Agriculture Organization of the United Nations. Available at: (accessed 13 January 2017).

Gelfand I, Zenone T, Jasrotia P, et al. (2011) Carbon debt of Conservation Reserve Program (CRP) grasslands converted to bioenergy production. Proceedings of the National Academy of Sciences of the United States of America 108 (33): 13864–13869.

Ghosh A (2016) Systems and synthetic biology for the microbial production of biofuels. Current Metabolomics 4: 5–13.

Goldemberg J and Guardabassi P (2010) The potential for first‐generation ethanol production from sugarcane. Biofuels, Bioprod. Bioref. 4: 17–24. DOI: 10.1002/bbb.186.

Hess JR, Wright CT and Kenney KL (2007) Cellulosic biomass feedstocks and logistics for ethanol production. Biofuels, Bioproducts and Biorefining 1: 181–190.

Hill J, Nelson E, Tilman D, Polasky S and Tiffany D (2006) Environmental, economic, and energetic costs and benefits of biodiesel and ethanol biofuels. Proceedings of the National academy of Sciences of the United States of America 103 (30): 11206–11210.

Hill N (2016) SULTAN Modelling to Explore the Wider Potential Impacts of Transport GHG Reduction Policies in 2030. Ricardo Energy & Environment for the European Climate Foundation. Ref. DG‐1509‐55582, ePublication available at:‐content/uploads/2016/02/ECF‐Transport‐GHG‐reduction‐for‐2030_Final_Issue21.pdf

Hillen LW, Pollard G, Wake LV and White (1982) Hydrocracking of the oils of Botryococcus braunii to transport fuels. Biotechnology and Bioengineering 24: 193–205.

Hook M and Tang X (2012) Depletion of fossil fuels and anthropogenic climate change – a review. Energy Policy 52: 797–809.

Hoekman SK, Broch A, Robbins C, Ceniceros E and Natarajan M (2012) Review of biodiesel composition, properties and specifications. Renewable and Sustainable Energy Reviews 16: 143–169.

Howard TP, Middelhauffe S, Edner C, et al. (2013) Production of drop‐in transport fuel by Escherichia coli. Proceedings of the National Academy of Sciences of the United States of America 110: 7636–7641.

Huang H, Long S and Singh V (2016) Techno‐economic analysis of biodiesel and ethanol co‐production from lipid‐producing sugarcane. Biofuels, Bioproducts and Biorefining 10 (3): 299–315.

IEA (2011) Key World Energy Statistics. IEA.‐worldenergy‐statistics.html

Janssen R and Rutz DD (2011) Sustainability of biofuels in Latin America: risks and opportunities. Energy Policy 39 (10): 5717–5725.

Jones JA, Toparlak OD and Koffas MAG (2015) Metabolic pathway balancing and its role in the production of biofuels and chemicals. Current Opinion in Biotechnology 33: 52–59.

Koçar G and Civaş N (2013) An overview of biofuels from energy crops: current status and future prospects. Renewable and Sustainable Energy Reviews 28: 900–916.

Koh MY, Idaty T and Ghazi M (2011) A review of biodiesel production from Jatropha curcas L. oil. Renewable and Sustainable Energy Reviews 15: 2240–2251.

Kumar P, Barrett DM, Delwiche MJ and Stroeve P (2009) Methods for Pretreatment of Lignocellulosic Biomass for Efficient Hydrolysis and Biofuel Production. Industrial and Engineering Chemistry Research 48: 3713–3729.

Kwanchareon P, Luengnaruemitchai A and Jai‐In S (2006) Solubility of a diesel–biodiesel–ethanol blend, its fuel properties, and its emission characteristics from diesel engine. Fuel 86: 1053–1061.

Lee S, Speight J and Loyalka S (2007) Handbook of Alternative Fuel Technologies. Second Edition, USA: CRC Press, Taylor & Francis Group. ISBN 9781466594562

Lee SY, Kim HM and Cheon S (2015) Metabolic engineering for the production of hydrocarbon fuels. Current Opinion in Biotechnology 33: 15–22.

Leite GB, Abdelaziz AEM and Hallenbeck PC (2013) Algal biofuels: challenges and opportunities. Bioresource Technology 145: 134–141.

Margeot A, Hahn‐Hagerdal B, Edlund M, Slade R and Monot F (2009) New improvements for lignocellulosic ethanol. Current Opinion in Biotechnology 20: 372–380.

Mata TM, Martins AA and Caetano NS (2010) Microalgae for biodiesel production and other applications: a review. Renewable and Sustainable Energy Reviews 14: 217–232.

Martien JI and Amador‐Noguez D (2017) Recent applications of metabolomics to advance microbial biofuel production. Current Opinion in Biotechnology 43: 118–126.

Mathews JA (2008) Carbon‐negative biofuels. Energy Policy 36 (3): 940–945.

McKendry P (2002) Energy production from biomass (part 1): overview of biomass. Bioresource Technology 83 (1): 37–46.

McKennedy J and Sherlock O (2015) Anaerobic digestion of marine macroalgae: a review. Renewable & Sustainable Energy Reviews 52: 1781–1790.

Mullet J, Morishige D, McCormick R, et al. (2014) Energy Sorghum – a genetic model for the design of C4 grass bioenergy crops. Journal of Experimental Botany 65: 3479–3489.

Murray SC, Rooney WL, Hamblin MT, et al. (2009) Sweet sorghum genetic diversity and association mapping for Brix and height. Plant Genome 2 (1): 48–62.

Murugesan A, Umarani C, Subramanian R and Nedunchezhian N (2009) Bio‐diesel as an alternative fuel for diesel engines – a review. Renewable and Sustainable Energy Reviews 13: 653–662.

Naik SN, Goud VV, Rout PK and Dala AK (2010) Production of first and second generation biofuels: a comprehensive review. Renewable and Sustainable Energy Reviews 14 (2): 578–597.

Office of Energy Efficiency and Renewable Energy (2016) Fuel Economy Guide. Washington, DC: DOE/EE‐1249, US Department of Energy/US Environmental Protection Agency.

Olsson L and Hahn‐Hägerdal B (1996) Fermentation of lignocellulosic hydrolysates for ethanol production. Enzyme and Microbial Technology 18 (5): 312–331.

Papini M, Nookaew I, Uhlén M and Nielsen J (2012) Scheffersomyces stipitis: a comparative systems biology study with the Crabtree positive yeast Saccharomyces cerevisiae. Microbial Cell Factories 11: 136.

Palmqvist E and Hahn‐Hägerdal B (2000) Fermentation of lignocellulosic hydrolysates. II: inhibitors and mechanisms of inhibition. Bioresource Technology 74 (1): 25–33.

Pimentel D and Patzek TW (2005) Ethanol production using corn, switchgrass, and wood; biodiesel production using soybean and sunflower. Natural Resources Research 14 (1): 65–76.

Ra K, Shiotsu F, Abe J and Morita S (2012) Biomass yield and nitrogen use efficiency of cellulosic energy crops for ethanol production. Biomass and Bioenergy 37: 330–334.

Renninger NS, Ryder JA and Fisher KJ (2011) Jet Fuel Compositions and Methods of Making and using the Same. US Patent 7,935,156.

Richardson Y, Blin J and Julbe A (2012) A short overview on purification and conditioning of syngas produced by biomass gasification: catalytic strategies, process intensification and new concepts. Progress in Energy and Combustion Science 38: 765–781.

Sarath G, Mitchell RB, Sattler SE et al. (2008) Opportunities and roadblocks in utilizing forages and small grains for liquid fuels. J Ind Microbiol Biotechnol 35: 343–354. DOI: 10.1007/s10295-007-0296-3.

Scott SA, Davey MP, Dennis JS, et al. (2010) Biodiesel from algae: challenges and prospects. Current Opinion in Biotechnology 21: 277–286.

Shapouri H, Duffield JA and Wang M (2002) The Energy Balance of Corn Ethanol: An Update. U.S. Department of Agriculture, Office of Chief Economist, Office of Energy Policy and New Use, Agricultural Economic Report No. 814, Washington, DC, p. 16.

Shaw AJ, Podkaminer KK, Desai SG, et al. (2008) Metabolic engineering of a thermophilic bacterium to produce ethanol at high yield. Proceedings of the National Academy of Sciences of the United States of America 105 (37): 13769–13774.

Shekiro J III, Kuhn EM, Nagle NJ, et al. (2014) Characterization of pilot‐scale dilute acid pretreatment performance using deacetylated corn stover. Biotechnology for Biofuels 7 (1): 23.

Shoemaker CE and Bransby DI (2010) The role of sorghum as a bioenergy feedstock. In: Ross Braun, Doug Karlen and Dewayne Johnson Sustainable Alternative Fuel Feedstock Opportunities, Challenges and Roadmaps for Six U.S. Regions. Proceedings of the Sustainable Feedstocks for Advanced Biofuels Workshop.

Sims REH, Mabee W, Saddler JN and Taylor M (2009) An overview of second generation biofuel technologies. Bioresource Technology 101: 1570–1580.

Smeets EMW, Bouwman AF, Stehfest E, van Vuuren DP and Posthuma A (2009) Contribution of N2O to the greenhouse gas balance of first‐generation biofuels. Global Change Biology 15 (1): 1–23.

Weiland P (2010) Biogas production: current state and perspectives. Applied Microbiology and Biotechnology 85: 849–860.

Further Reading

Chiaramonti D, Prussi M, Ferrero S, et al. (2012) Review of pretreatment processes for lignocellulosic ethanol production, and development of an innovative method. Biomass and Bioenergy 46: 25–35.

Hu F and Ragauskas A (2012) Pretreatment and lignocellulosic chemistry. Bioenergy Research 5 (4): 1043–1066.

Liao JC, Luo M, Pontrelli S and Luo S (2016) Fuelling the future: microbial engineering for the production of sustainable biofuels. Nature Reviews. Microbiology 14: 288–304.

Love J and Bryant JA (eds) (2017) Biofuels and Bioenergy. ISBN: 978-1-118-35056-0.

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Wojcik, Emilia Z, Singleton, Chloe, Chapman, Liam NM, Parker, David A, and Love, John(Jun 2017) Plant Biomass as Biofuels. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1002/9780470015902.a0023716]