Life Cycle Assessment of Battery-Based Ship Electrification: A Methodological Review of Assumptions, Comparability, and Limitations

Battery-based electrification is increasingly recognised as a key pathway for reducing greenhouse-gas emissions in maritime transport, particularly for vessel segments characterised with short, predictable operation profiles. To ensure an environmentally sustainable transition, it is essential to quantify the potential environmental benefits of these solutions. Life Cycle Assessment (LCA), standardised by ISO 14040 and ISO 14044, is the internationally recognised methodology for evaluating environmental impacts across the entire life cycle and for consistently comparing options providing the same function. This study presents a methodological review of LCA applications to battery-based ship electrification, with the objective of analysing key assumptions, comparability issues, and limitations across the existing literature. A systematic review was conducted on 24 studies, focusing on core methodological aspects, including product system definition, functional unit selection, system boundaries, life cycle inventory modelling, and impact assessment methods, while considering contextual elements such as fleet segmentation and propulsion configurations to support the interpretation of methodological choices. The analysis reveals significant methodological heterogeneity across studies, particularly in product-system definitions, functional unit selection, modelling detail, and impact category coverage, which limits cross-study comparability. This review also highlights a strong concentration of applications on short-route passenger ferries, while other vessel categories remain underrepresented, further constraining the generalisability of the findings. Although a direct quantitative comparison of results is not methodologically appropriate due to this heterogeneity, climate change mitigation consistently emerges as a key benefit across the analysed studies. At the same time, the multi-impact perspective of LCA highlights relevant trade-offs related to material use, toxicity, and resource depletion. Overall, the findings underline the need for more harmonised methodological approaches and a holistic life cycle perspective to support robust and comparable environmental assessments as battery-based solutions expand within the maritime sector. This review provides a structured interpretation of methodological variability and identifies priorities for future LCA applications.