In the maritime domain, hydrogen fuel cell propulsion and autonomous vessels are two important issues that are yet to be implemented together because of a few challenges. It is obvious that there are several individual safety studies on Maritime Autonomous Surface Ships and hydrogen storage as well as fuel cells based on various risk assessment tools but the combined safety studies that include hydrogen fuel cells on autonomous vessels with recent risk analysis methods are extremely limited. This research chooses the “System-Theoretic Process Analysis” (STPA) method which is a recent method for potential risk identification and mitigation. Both hydrogen and autonomous vessels are analyzed and assessed together with the STPA method. Results are not speculative but rather flexible compared to conventional systems. The study finds a total of 44 unsafe control actions (UCAs) evolved from human and central control unit controllers through STPA. Further, the loss scenarios (LS) are identified that lead to those UCAs so that loss scenarios can be assessed and UCAs can be mitigated for safe operation. The objective of this study is to ensure adequate safety for hydrogen fuel cell propulsion on autonomous vessels.

A critical challenge in the safe operation of autonomous vessels is ensuring that control commands are executed accurately and promptly by both shore-side and onboard systems. In this paper, we build on a use case of an autonomous ship, where the control hierarchy includes Human Operators on the shoreside, along with the Ship Motion Controller, Power Management System, and Battery Management System, among other controllers on the shipside. Incorrect execution of control actions by these controllers can lead to hazardous situations of varying severity. This study aims to identify and analyze hazards related to these four controllers and provide insights into how inadequate control may occur and create hazardous situations with the controllers. Recently, STPA has emerged as the mainstream approach for identifying hazards resulting from control action failures. Therefore, this study applies the System Theoretic Process Analysis (STPA) method to explore how control actions of different controllers might fail, ensuring safe operation. A control structure hierarchy has been developed that identifies (1) control actions and (2) feedback signals between controllers based on their responsibilities. Using STPA, a total of 127 unsafe control actions are identified that could result in hazards. We classify the significance of Unsafe Control Actions based on hazard severity, operational mode, and suggest the level of attention each controller requires. The results offer a structured foundation for prioritizing safety–critical control actions in battery-powered autonomous ships, facilitating more effective risk mitigation strategies for designers, operators, and regulators.