Fuel Saving Effect of Hybrid Propulsion System - Case: Tugboat is not in Service

Hybrid propulsion systems are attracting more attention as a way to save fuel. In an attempt to apply this system that does not have a large battery capacity to a tugboat, the authors have studied the correlation between its control method and efficiency on the condition that the tugboat was not in service. Data is calculated by using a simulation model that the authors had developed. When it comes to hybrid propulsion system, it is important to control size and direction of energy. Three control patterns were presented and evaluated in a comprehensive way taking controllability, redundancy, and efficiency of the entire system into consideration. The simulation results highlighted the main characteristics of the control patterns. They also made it clear that decreasing energy loss in a slipping clutch contributes to improving hybrid propulsion system efficiency.