Multi-objective optimization of large cruise ship power plant configuration based on NSGA-Ⅱ algorithm and AHP-entropy weighted TOPSIS-VIKOR

• Multi-objective optimization of the power plant of a 135,500 GT cruise ship. • Economic, energy efficiency and technical criteria are jointly used to assess generator set options for the cruise ship. • NSGA-II, combined with an AHP–entropy weighted TOPSIS–VIKOR approach, is used to rank Pareto optimal configurations. • MGO, LNG and methanol dual-fuel generator set combinations are compared for the case ship. • Changes in fuel price can reverse the preferred power plant configuration within the Pareto set. Large cruise ships are characterized by intricate power loads and fluctuating operational conditions, which introduce significant safety hazards, complicate energy efficiency optimization and present challenges in the spatial arrangement of onboard systems. Optimizing the power plant configuration of large cruise ships can enhance system redundancy and reliability, mitigate failure risks, leverage diverse energy sources to improve overall efficiency, and employ modular design principles to reduce system mass and spatial footprint. This study incorporates a multi-faceted objective framework, including economic indicators, the energy efficiency design index, generator set reliability, maximum ship speed, generator set mass, and volume considerations, to comprehensively address the unique operational and structural characteristics of large cruise ships. The Non-dominated Sorting Genetic Algorithm II (NSGA-II), in combination with the Analytic Hierarchy Process (AHP)-entropy weighted TOPSIS-VIKOR method, is employed to ascertain the optimal power plant configuration by comprehensively considering all relevant assessment indicators. The results indicate that operational expenditure and maximum ship speed are the most critical factors influencing configuration optimization. Among all configurations, generator sets powered by Marine Gas Oil (MGO) exhibit the most balanced performance, whereas those utilizing alternative fuels present varying disadvantages—for instance, generators fueled by Liquefied Natural Gas (LNG) are significantly less cost-effective. Under the assumed operating profile and the reference performance parameters adopted in this study, the fuel price sensitivity analysis indicates that the MGO-fueled generator configuration (i.e., 4 × Wärtsilä 16V31 and 3 × Wärtsilä 14V31) yields the best overall performance across the examined fuel price range. In contrast, configurations using alternative fuels exhibit greater sensitivity to price fluctuations, resulting in variations in their configuration rankings. The methodology delineated in this paper enhances the evaluative criteria for cruise ship power plant configuration and provides shipowners with more viable alternatives, customized to the unique operational and structural dynamics of cruise ships. The combination of AHP entropy weight TOPSIS-VIKOR and NSGA-II is first applied to the configuration optimization of large cruise ship power systems to strengthen decision support for selecting an implementable solution.