Towards sustainable maritime distribution: Developing an optimal fleet distribution model

Abstract

Maritime transportation is a key component of global trade, but its contribution to greenhouse gas (GHG) emissions necessitates more sustainable fleet distribution strategies. To support compliance with International Maritime Organization (IMO) MARPOL Annex VI regulations, this study develops an optimal fleet distribution model aimed at minimizing the Carbon Intensity Indicator (CII) while ensuring operational feasibility. The model is formulated using Mixed-Integer Linear Programming (MILP) and evaluated through Variable Neighborhood Search (VNS) across multiple operational scenarios. A case study on LNG distribution in the Bali-Nusa Tenggara region is conducted to assess the model’s effectiveness. The results show that Scheme 1 and Scheme 4 consistently achieve the lowest CII values, making them the most suitable configurations under IMO compliance criteria. The comparison between VNS and MILP demonstrates that VNS can efficiently approximate MILP results while maintaining computational efficiency in optimizing fleet assignments. The scenario analysis further highlights that capacity constraints play a critical role in determining CII values, emphasizing the importance of selecting the appropriate fleet size and allocation strategy. The findings suggest that optimizing fleet selection and route distribution can significantly reduce carbon emissions while maintaining cost-effective operations. This study provides a structured and data-driven approach to sustainable maritime distribution, offering practical insights for industry stakeholders to achieve both environmental compliance and operational efficiency.