Design and Optimization of a Hybrid Energy System for an Ice-Class Research Vessel

Abstract

Hybrid energy systems are investigated as a viable alternative to conventional energy systems typically consisting of multiple diesel engines, on ice class vessels. Vessels bearing ice class notation experience significant disparities in load profiles between typical voyages and those involving occasional icy conditions. Ice class rules mandate considerably higher installed power than necessary for regular service, which can reduce the average operating efficiency of a conventional energy system. This paper demonstrates the performance of a 50-meter research vessel operating mainly in the Baltic Sea with ice class 1A. Ship resistance is calculated in open water and ice, characteristic time-based load profiles are generated for a selected route over three voyage conditions, and various hybrid energy system configurations are analyzed. The peak propulsion loads even in mild winter conditions with ice are observed to be over 4 times as high as open water operation in summer. Results indicate that modularizing the energy system with multiple gensets results in 6.9%, 7.8% and 13.8% energy savings over the three voyages. While battery hybridization does not show outright fuel savings over most voyages, it compensates for non-optimal modularity of the gensets over specific voyages by yielding up to 1.8% fuel savings and enables optimal energy system operation over a wider range of voyages. Finally, it is determined that an ice class certified energy system performs just as efficiently as a comparable downsized energy system, if the genset installation is appropriately modularized.