Wind-Assisted Propulsion Systems in the Carbon-Neutral Era: A Systematic Review of Multi-Modal Technologies

The global shipping industry faces substantial pressure to reduce greenhouse gas emissions to comply with the International Maritime Organization's stringent reduction policies. Consequently, wind-assisted propulsion systems (WAPs) have garnered extensive research interest due to their utilization of clean energy and the widespread availability of wind resources. However, previous reviews predominantly focused on literature published before 2020 or concentrated on single systems, lacking a systematic comparative analysis of multiple wind propulsion technologies. This review systematically examines WAPs, focusing on their development path, current status, and future trends. Our findings delineate three distinct developmental stages in WAPs research: aerodynamic fundamentals (2000-2015), performance optimization (2015-2020), and system integration (2021-present). Four main technologies dominate current research directions: rigid sails, Flettner rotors, kite systems, and hybrid configurations. With technological advancements, theoretical research has shifted from complex computational fluid dynamics toward systematic evaluations of the economic and environmental benefits of entire ship systems. Nevertheless, notable research gaps persist, including the absence of a comprehensive life cycle assessment framework, insufficient real-world operational data from commercial deployments, and inadequate maturity in control strategies for integrated systems. Ultimately, this review offers a comprehensive knowledge framework for researchers and practitioners, providing data-driven recommendations for technological advancement and carbon neutrality policy formulation.