The maritime sector faces mounting pressure to decarbonise in alignment with global climate objectives and regional frameworks such as the EU Fit-for-55 package and the IMO net-zero targets. For fleet operators such as the Port of Rotterdam, which aims to reduce Scope 1 and 2 emissions by 90% in 2030 and sail emissions-free from 2035, this involves navigating complex trade-offs between sustainability, cost-efficiency, and operational readiness. This thesis investigates how the Port of Rotterdam can optimise its fleet renewal strategy to minimise total polluting emissions and transition costs while maintaining functional capacity.

To address this challenge, a hybrid decision-support framework was developed, combining multi -objective optimisation with multi-criteria decision analysis. The optimisation model produced Pareto optimal strategies, using the ε-constraint method, that balance lifecycle CO2 emissions, total cost of ownership, and local air pollution. Multi-criteria decision analysis, using TOPSIS, enabled inclusion of stakeholder preferences in the classification of different transition schedules under varying assumptions about fuel types, material choice, and production location. Scenario analyses were performed to assess the robustness of the combined framework against various economic outlooks and environmental choices, such as fuel type, hull material, and production location.

The results show that lifecycle emissions are largely shaped by design decisions such as material and energy source, whereas local pollutants are very sensitive to the replacement schedule. The total cost of ownership shows limited sensitivity to scheduling (1–2% variation), while battery production and dismantling emerge as the dominant drivers of greenhouse gas emissions and financial impact. The inclusion of CO2 emission depreciation significantly altered the schedules of optimal results, raising ethical and policy considerations. Certain vessel classes demonstrated robust scheduling behaviour, in various strategic choices and economic scenarios, identifying them as low regret alternatives. Other classes were more sensitive to changes in the strategic choices or stakeholder preferences.

The framework successfully supported trade-off navigation, revealing how rankings changed under varying stakeholder preferences and scenario assumptions. However, several simplifications remain. The decoupled class structure limited the ability to model shared infrastructure and battery packs. The cost structures did not reflect strategic procurement differences, and the lifecycle assessment focused solely on CO2-equivalent emissions, excluding other impact categories such as toxicity or resource depletion. These limitations suggest that future extensions should integrate infrastructure co-optimisation, procurement variation, and broader environmental metrics to fully capture the system-level implications
of fleet renewal.

This research contributes a replicable, stakeholder-aligned methodology for sustainable fleet transition planning. It provides the Port of Rotterdam with a transparent and data-driven tool to align its environmental commitments with long-term operational and financial viability, providing critical insights for fleet operators pursuing low-emission transitions.