Advancing Green Maritime Propulsion: A Comprehensive Study of Electric and Hybrid Systems and Emerging Trends

The maritime sector is increasingly focused on green propulsion technologies to address stringent regulations on greenhouse gas emissions and other pollutants. In recent years, research has proposed novel electric and hybrid propulsion architectures and advanced energy management systems. This paper reviews the fundamentals and the most recent developments of hybrid and electric propulsion technologies, evaluating their environmental and economic implications. Particular attention is given to the various onboard energy storage, conversion, and generation technologies, outlining their potential and limitations. Through the analysis of numerous research studies in alternative marine propulsion, the suitability of Li-ion batteries, supercapacitors, flywheels, and different types of fuel cells for maritime transport needs is evaluated, along with the possibilities offered by renewable energy to reduce the environmental impact of marine energy systems. Additionally, it discusses important future directions, research gaps, and emerging paradigms in sustaining maritime eco-systems. Unlike previous reviews that mainly focus on individual technologies, this study provides an integrated analysis connecting propulsion architectures, energy storage systems, fuel cells, alternative fuels, renewable energy integration, and energy management strategies. The review also discusses technology limitations, operational suitability for different vessel categories, and future research challenges toward maritime decarbonization. In presenting these issues, the author’s intention is to promote interdisciplinary cooperation between shipbuilders, policymakers, and researchers for the benefit of more sustainable development of the maritime industry.