Methodological Approaches to Battery-Powered Ro-Pax Ferries in Domestic Shipping: A Systematic Review of Route-Based Case Studies

Maritime transport is responsible for 3% of global greenhouse gas (GHG) emissions, making it a focus of decarbonization efforts. Ro-pax ferries, operating in the domestic shipping, are particularly emission-intensive due to their high operational frequency, while advances in battery-powered propulsion suggest that electrification is feasible on short to medium distance routes. This paper uses a systematic literature review of studies published between 2014 and 2024 to investigate the application of battery-powered ferries from a maritime transport system perspective. Using the PRISMA 2020 guidelines, the authors identified 15 case-study-based papers on battery-powered ferries, with a specific focus on the methodological approaches applied to domestic shipping routes. The goal of this review is to identify and systematize the methodologies used in case study research to analyze the implementation of battery-powered ferries on specific routes. The review contributes a structured synthesis of (I) methodological approaches, grouped into four clusters, and (II) route framing and selection practices using a three-level route classification, revealing an increasing methodological complexity, from single-route feasibility assessments to diversified, maritime network-integrated approaches. The paper systematically links existing methodologies to operational and conceptual case studies, providing practical insights for future decarbonization projects.