As global regulations and International Maritime Organization (IMO) targets intensify, the maritime sector faces increasing pressure for decarbonization, reduction of greenhouse gas emissions and improvement of energy efficiency. Conventional marine auxiliary power systems, typically marine diesel generators, operate at low electrical efficiencies (25–45 %) and produce significant emissions. Bio-methanol, a renewable liquid fuel produced from biomass or renewable electricity, offers an attractive alternative for the yachting sector due to its high energy density, ambient-condition storage, compatibility with existing infrastructure, and ability to yield hydrogen-rich reformate gas for fuel cells. However, integrating methanol steam reforming (MSR) with solid oxide fuel cells (SOFCs) in marine environments remains largely unexplored in the literature.

This thesis investigates the design and modeling of an integrated bio-methanol steam reforming (MSR)–solid oxide fuel cell (SOFC)–Organic Rankine Cycle (ORC) system for a Feadship superyacht, developed in Aspen Plus. The bio-methanol reformer supplies hydrogen-rich gas to the SOFC stack, which subsequently drives both electric generation and heat recovery. Component integration includes thermal coupling between the MSR reactor, the afterburner, preheaters, and the ORC. The system meets auxiliary power demands from 225 kW to 325 kW and is modeled at three representative auxiliary power levels: 225 kW, 275 kW, and 325 kW. Motivated by the need to optimize both system efficiency and heat management, this work addresses a critical research gap in the techno-economic assessment of renewable methanol-based SOFC power systems for maritime applications.

The model incorporates MSR kinetics, SOFC electrochemistry—including activation, ohmic, and concentration losses—and waste heat recovery. Iterative SOFC area sizing and heat integration strategies are developed and validated, while an analysis of the operational expenditure of the system is also included. Sensitivity analyses investigate the influence of SOFC fuel utilization and operating temperature on the system’s performance and consumption of resources. Analyzing key performance indicators, such as electrical generation efficiency and combined heat and power (CHP) efficiency, under different load conditions, has revealed that at the 225 kW partial-load condition, the system achieves a maximum electrical generation efficiency of 57.2% and a CHP efficiency of 79.4%, significantly outperforming conventional marine diesel generators. At the intermediate 275 kW load, the system reaches an electrical generation efficiency of 54.3% and a CHP efficiency of 71.5%. At full load (325 kW), the corresponding efficiencies are equal to 52.0% and 65.9% respectively.

The results confirm the technical feasibility of bio-methanol-fueled SOFC systems for superyacht applications and demonstrate their potential for significant efficiency gains. The developed model provides a foundation for future optimization, hybridization strategies, and onboard integration, supporting sustainable decarbonization in the maritime sector.

In the context of maritime decarbonization, methanol has emerged as a promising alternative fuel due to its favorable storage properties and potential for renewable production. This thesis investigates the techno-economic performance of integrating methanol steam reforming with low-temperature proton exchange membrane fuel cells (LT-PEMFCs) for on-board power generation on a super-yacht. The primary objective is to conduct a comparative analysis of two distinct system architectures: an integrated membrane reactor where reaction and separation occur simultaneously (Configuration A), and a conventional packed-bed reactor followed by a separate membrane purification unit (Configuration B).

To evaluate these systems, two detailed, steady-state process models were developed using the Aspen Plus V12 simulation software. The core unit operations, including the coaxial membrane reformer and the PEM fuel cell, were modelled using custom-developed User2 Fortran subroutines. These subroutines implement detailed, literature-based models for the MSR kinetics (Peppley et al.), hydrogen permeation (Sieverts’ Law), and PEMFC electrochemistry (Correa et al.). The systems were sized to meet a 325 kW net power demand derived from real-world Feadship vessel load data, and comprehensive heat integration strategies were implemented for both.

The simulation results reveal a fundamental trade-off between unit-level conversion efficiency and system-level thermal efficiency across the different power loads. While the membrane reactor (Configuration A) achieved superior methanol conversion due to in-situ hydrogen removal, its fuel-depleted retentate stream necessitated a significant supplementary fuel flow to the burner for heat integration. In contrast, the conventional packed-bed reactor (Configuration B), despite a lower conversion, produced a fuel-rich retentate that greatly improved the effectiveness of its heat recovery loop.

Consequently, Configuration B demonstrated a higher overall system efficiency (59%) and lower specific methanol consumption compared to Configuration A (57%) at the design point. The operational cost analysis further confirmed this advantage, showing lower annual fuel and membrane replacement costs for Configuration B. This study concludes that for an integrated onboard power system where retentate fuel value is critical for thermal self-sufficiency, the conventional reactor with a separate purification unit represents the more efficient and economically viable architecture. Both modelled systems, however, show significant efficiency and emissions advantages over traditional marine diesel engines, validating the promise of methanol-reforming PEMFC technology for sustainable maritime applications.