Conversion of biomass to biofuels and life cycle assessment: a review

Ahmed I. Osman*, Neha Mehta, Ahmed M. Elgarahy, Amer Al-Hinai, Ala’a H. Al-Muhtaseb, David W. Rooney

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

287 Citations (Scopus)


The global energy demand is projected to rise by almost 28% by 2040 compared to current levels. Biomass is a promising energy source for producing either solid or liquid fuels. Biofuels are alternatives to fossil fuels to reduce anthropogenic greenhouse gas emissions. Nonetheless, policy decisions for biofuels should be based on evidence that biofuels are produced in a sustainable manner. To this end, life cycle assessment (LCA) provides information on environmental impacts associated with biofuel production chains. Here, we review advances in biomass conversion to biofuels and their environmental impact by life cycle assessment. Processes are gasification, combustion, pyrolysis, enzymatic hydrolysis routes and fermentation. Thermochemical processes are classified into low temperature, below 300 °C, and high temperature, higher than 300 °C, i.e. gasification, combustion and pyrolysis. Pyrolysis is promising because it operates at a relatively lower temperature of up to 500 °C, compared to gasification, which operates at 800–1300 °C. We focus on 1) the drawbacks and advantages of the thermochemical and biochemical conversion routes of biomass into various fuels and the possibility of integrating these routes for better process efficiency; 2) methodological approaches and key findings from 40 LCA studies on biomass to biofuel conversion pathways published from 2019 to 2021; and 3) bibliometric trends and knowledge gaps in biomass conversion into biofuels using thermochemical and biochemical routes. The integration of hydrothermal and biochemical routes is promising for the circular economy.

Original languageEnglish
Pages (from-to)4075-4118
Number of pages44
JournalEnvironmental Chemistry Letters
Issue number6
Publication statusAccepted/In press - 2021


  • Biochemical
  • Biofuel
  • Biomass
  • Life cycle assessment
  • Thermochemical

ASJC Scopus subject areas

  • Environmental Chemistry


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