Hybrid technology in marine vehicles can significantly reduce fuel consumption and local CO₂ emissions. It has been applied successfully to several ship-types, mostly with conventional, rule-based, strategies. To further improve performance, intelligent control strategies are necessary. This work, inspired by automotive research in Energy Management Strategies, applies the Equivalent Consumption Minimisation Strategy (ECMS) to a ship powered by a hybrid propulsion plant with hybrid power supply that can be recharged with renewable shore power. This hybrid configuration has the additional challenge to determine the optimal power-split between three or more different power sources, in real-time, and to optimally deplete the battery packs over the mission profile. To this end, a Mixed-Integer Non-Linear optimisation Problem is formulated and solved by combining Branch & Bound and Convex optimisation. Dynamic Programming (DP) is used to benchmark the real-time strategies, which are also compared to the current rule-based (RB) controller. Simulation results of a case study tugboat with validated models show that, with unknown load demand, 6% additional fuel savings can be achieved with ECMS.

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In this paper we focus on integration of batteries with ship power systems for three application cases. Presented application cases include two platform supply vessels, one equipped with diesel engines and other with dual fuel engines, and a heavy lift crane vessel. Besides reducing the number of running engines and maintaining original dynamic positioning capabilities, we also demonstrate novel possibilities of battery usage, such as harvesting of waste energy, and implementation of dual fuel engines for dynamic positioning. In all application cases, results indicate significant fuel savings and reduction of running hours due to spinning reserve function of batteries.@en