Structured review of maritime life cycle assessment: Applications, methods, and challenges

The maritime industry, a fundamental component of global commerce, is currently undergoing a significant transformation driven due to technological advancements, environmental imperatives, and dynamic geopolitical conditions. Life Cycle Assessment (LCA) provides a comprehensive methodology for evaluating emission reduction technologies across their full life cycle. This study presents a structured and criteria-based literature review of LCA applications in the maritime sector. Literature was identified using predefined search strings in the Scopus and Web of Science databases and screened through explicit inclusion and exclusion criteria, resulting in a final sample of 70 peer-reviewed articles from an initial set of 826 publications. The selected studies were evaluated according to the ISO 14,044 framework and the documentation quality assessment developed by Keiser et al., which comprises 13 categories assessed using a binary scoring system. The evaluation reveals an overall methodological compliance rate of 49 %, indicating substantial heterogeneity in implementation and reporting. While system boundaries and functional units are generally well defined, significant gaps persist in data quality requirements, allocation procedures, and uncertainty analysis. Overall, the review demonstrates that maritime LCA research has expanded rapidly but remains methodologically inconsistent. Strengthening methodological transparency, expanding system boundaries, improving access to primary operational data, and incorporating systematic uncertainty analysis are essential steps to enhance the reliability and policy relevance of future environmental assessments in the maritime sector.