Life cycle assessment of liquid biofuels: What does the scientific literature tell us? A statistical environmental review on climate change

More than 580 peer-reviewed articles dealing with life cycle assessment (LCA) of biofuels, published from 2012 to 2020, were identified in the scientific literature. Articles without a clear and complete LCA hypothesis were discarded. This resulted into 172 useable articles, providing 566 carbon footprints. LCA of biofuels is a topic that has attracted increasing interest in recent times, with an average production of 20 papers per year on the subject. The objectives addressed range from installation optimisation and the assessment of new types of biomass to comparison of pathways and the impact of methodological choices in LCA. The analysis of published carbon footprints reveals a hierarchy in terms of the carbon footprint of diesel, gasoline, and jet fuel substitutes. The type of feedstock appears to be a determinant. Data collected from the literature highlight that biofuels’ carbon footprint varies greatly. However, the climate change mitigation potential of some pathways can be clearly confirmed. Methodological choices adopted by LCA practitioners remain an important source of differences in LCA results, as the allocation choices for co-products or the inclusion of land use change can lead to a wide range of results. The carbon neutrality principle also has the potential to influence LCA results, as described in the statistical analysis. Through an extensive literature review and a statistical analysis using econometric methods, this work provides an overview and analysis of the variability of the environmental impacts of biofuels in terms of greenhouse gas (GHG) to help shape stakeholder decision-making. • A comprehensive LCA review analysing 585 biofuel articles from 2012 to 2020. • A meta-analysis relying on 566 carbon footprints observations from 172 articles. • Diesel, gasoline, and jet fuel substitutes' GHG emissions assessed in the study. • High disparity among biofuels depending on the feedstock and the substitution pool. • Overall median value: 40 g CO 2 eq./MJ, and standard deviation: 65 g CO 2 eq./MJ.