Abstract
The maritime sector faces increasing pressure to align with the International Maritime Organization (IMO)’s 2050 net-zero greenhouse gas (GHG) goals. Compared with traditional measures such as technical efficiency improvements or operational speed adjustments, the substitution of fossil fuels with zero-and net-zero (ZNZ) fuels (such as methanol, ammonia, and hydrogen) offers the most transformative pathway for deep decarbonization. Recognizing this potential, it is crucial to assess the practical reduction in emissions that these fuels can achieve and to investigate their effective deployment in ports and on international shipping routes. To address this challenge, this thesis develops an integrated, multi-scale assessment framework through three interrelated studies.At the fuel level, the first study assesses the environmental performance of alternative marine fuels from a lifecycle perspective, encompassing both upstream production and downstream consumption processes in accordance with the IMO’s fuel assessment standards. An uncertainty-integrated lifecycle assessment (LCA) framework is developed by combining Monte Carlo simulations and sensitivity analysis with Automatic Identification System (AIS) data. This framework not only captures the influence of upstream regional electricity sources for fuel production but also assesses key operational factors such as pilot fuel ratios in dual-fuel engines, vessel speeds, and the performance of onboard carbon capture systems. Results demonstrate that such factors can significantly shift emission reduction outcomes, underscoring the need for uncertainty-integrated assessments to provide credible evidence for carbon pricing and investment decisions.
Building on the fuel-level evidence, the second study focuses on the adoption of alternative fuels in the port, where harbour craft, particularly heavy-duty tugboats, are major contributors to local emissions and are often prioritized for early fuel transition. To support fleet renewal decisions under real-world uncertainty, a two-stage robust optimization model is proposed to determine optimal tugboat fleet transition strategies across six fuel options (biodiesel, liquefied natural gas, methanol, hydrogen, ammonia, and electricity) under varying decarbonization targets. Using operational data from the Port of Singapore, the results reveal fuel-mix transition pathways that balance emission reduction objectives with operational reliability and cost considerations in port environments.
Extending the analysis to the system scale, the third study examines the feasibility of alternative fuels on long-distance shipping routes, where fuel characteristics directly influence vessel design, cargo capacity, and operational logistics. Using the Rotterdam–Singapore corridor as a case study, a comprehensive evaluation framework is developed that integrates AIS-derived vessel activity data with LCA and techno-economic analysis. The framework explicitly quantifies trade-offs associated with expanded fuel storage, increased refueling frequency, cargo capacity losses, and total cost of ownership. Comparative results indicate that renewable methanol, when combined with onboard carbon capture technologies, offers the most balanced pathway for long-haul container shipping, achieving near-zero GHG emissions while maintaining operational viability.
Overall, this thesis advances an integrated perspective on maritime decarbonization by systematically linking uncertainty-integrated lifecycle environmental assessment with port-level deployment strategies and corridor-level feasibility analysis. The findings provide decision-relevant evidence for policymakers, shipowners, and port authorities, supporting the scalable adoption of alternative marine fuels while enhancing the resilience and practicality of decarbonization strategies in the maritime sector.
| Date of Award | 2025 |
|---|---|
| Original language | English |
| Awarding Institution |
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| Supervisor | Hai YANG (Supervisor) |
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