Literature Review on Life Cycle Assessment of Transportation Alternative Fuels

Environmental concerns, such as global warming and human health damage, are intensifying, and the transportation sector significantly contributes to carbon and harmful emissions. This review examines the life cycle assessment (LCA) of alternative fuels (AF), evaluating current research on fuel types, LCA framework development, life cycle inventory (LCI), and impact selection. The objectives of this paper are: (1) to compare various AF LCA frameworks and develop a comprehensive framework for the transportation sector; (2) to identify emission hotspots of different AFs through simulations and real-world cases; (3) to review AF LCA research; (4) to extract valuable information for potential future research directions. The analysis reveals that all stages, except for hydrogen use, have an environmental impact. LCA boundaries and LCIs vary considerably depending on the raw materials, production processes, and products involved, leading to different emission hotspots. Due to knowledge or data limitations, some stages remain uncalculated in the current study, emphasizing the need for further refinement of the AF LCI. Future research should also explore the various impacts of widespread adoption of alternative fuels in transportation, encompassing social, economic, and environmental aspects. Lastly, the review provides structured recommendations for future research directions.