Environmental sustainability analysis of biofuels: a critical review of LCA studies

The use of fossil fuels in the transportation sector has significantly increased the greenhouse gas (GHG) emissions, leading to concerns about their environmental impact. As a result, biofuels have been promoted as a promising alternative to fossil fuels to mitigate GHG emissions. However, while biofuels are considered a low-carbon solution, there are concerns that its widespread use could have unforeseen environmental effects. This study analyzes the intricacies involved in biofuel's life cycle assessment (LCA). Fifty-three peer-reviewed studies were examined, covering a broad range of biofuels produced from over 25 different feedstocks. The literature review focused mainly on research published from 2012 to 2022 to avoid outdated information. The study found that second-generation biofuels have a greater potential for reducing GHG emissions than first-generation biofuels. However, the GHG emissions from third-generation biofuels are higher than those from conventional fuel, ranging from 10.2 to 1910 g CO2 eq. / MJ. The net energy ratio for biofuels ranges from 1.23 to 12.49 for first-generation, 0.003 to 15.04 for second-generation, and 3 to 18.5 for third-generation biofuels. The analysis also shows that the water footprint of biofuels is 50-240 times greater than fossil fuels. The study also examines the critical methodological aspects and sources of uncertainty in the LCA of biofuels and suggests solutions to address these problems. Overall, the study highlights the importance of taking a comprehensive approach when assessing the environmental impact of biofuels and the need for continued research to develop sustainable and effective biofuels.