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.