Wind-assisted propulsion systems for green shipping: A techno-economic review

Wind-assisted propulsion systems (WAPSs) are emerging and promising technologies for maritime decarbonization. Although WAPSs have witnessed rapid growth and commercial deployment in recent years, several challenges remain such as its inadequate propulsion efficiency, uncertain operational safety, insufficient economic assessment, and lack of standards and policy frameworks. The implementation of WAPSs is inherently multidisciplinary, with key concerns centered on safety, efficiency, and cost. To address these concerns, a state-of-the-art review of scientific research, industrial developments, and life cycle impact assessments of WAPSs is presented herein. Four types of WAPSs, namely rotor, boundary-layer control, wing, and kite sails, are classified and defined. This review covers critical aspects, including industrial and academic developments, unit aerodynamic characteristics, design procedure and considerations, operational challenges, and environmental, economic, social, and political impacts of WAPS deployment. Key limitations and challenges are also discussed, and nine critical future research directions are outlined. This review aims to provide a reference for guiding the safe, efficient, and cost-effective integration of WAPSs into green shipping.