Scamardella, Filippo (2025) Methanol as fuel for innovative marine propulsion systems. [Tesi di dottorato]

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Abstract

The marine sector is undergoing a critical transformation to meet global decarbonization goals. Methanol, a liquid fuel with favorable handling properties and potential for carbon neutrality, has emerged as a viable candidate for both propulsion and onboard energy systems. This thesis explores methanol-based energy converters for ships, comprising three technologies: single fuel spark-ignition engines, Molten Carbonate Fuel Cells (MCFC) coupled with CO₂ capture, and Reformed Methanol Fuel Cells (RMFC) integrated into a hybrid system with batteries and the associated energy management. The first part of the thesis focuses on the development and simulation of a methanol-fueled spark-ignition engine. A 0D model, supported by CFD data, is used to characterize combustion behavior, engine performance, and emissions under various operational conditions. Particular attention is given to the exhaust gas composition—specifically CO₂—which forms the basis for integration with downstream carbon capture technologies and to NOx which one of the most harmful compounds that might arise from methanol combustion. The second part investigates the potential of MCFCs to directly capture CO₂ from the engine’s exhaust. A detailed DWSim model is developed based on available data on methanol and diesel engines exhaust gasses. Experimental work supported the modeling effort of the complete plant through lab-scale testing of key MCFC’s components, such ceramic matrices for the electrolyte containment. In this context the system’s ability to generate power while reducing onboard CO₂ emissions is evaluated against the requirements from international regulations on a RoPax vessel chosen as case study. The third part of the thesis presents the design, simulation, and experimental validation of an RMFC system for power generation onboard. The RMFC is modeled in DWSim and integrated with a Simulink-based control framework to implement the Equivalent Consumption Minimization Strategy (ECMS) as energy management strategy for the tuning in simulation. Laboratory testing on a commercial system provided data for the thermodynamic and electrochemical modeling of the fuel cell system while Hardware-in-the-Loop tests on the complete power plant confirms system performance under varying loads and validates its suitability for hybrid operation with a battery pack in marine environments.

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