Performance assessment of a methanol-fueled SOFC-ICE system as a marine power solution: Thermodynamic analysis and comprehensive optimization

To meet the demand for low-carbon and high-efficiency marine power systems, this study investigates a hybrid system integrating a methanol-fueled solid oxide fuel cell (SOFC) with an internal combustion engine (ICE). Existing research often pursues efficiency improvement through complex thermodynamic cycles, leading to high system complexity and insufficient discussion and optimization of load regulation capability. Thus, this paper proposes a system configuration featuring efficient thermal integration and fuel coupling based on a fuel distribution strategy. Through thermodynamic analysis, the influence of key parameters on system performance and the safe adjustable range of the fuel distribution ratio (RF) is examined. Two improved integration strategies are further proposed: Option A reduces reformer heat demand via partial methanol reforming; Option B integrates a fuel turbine top cycle to enhance waste heat recovery from the SOFC cathode. Results show that both strategies improve system energy efficiency. Option A offers a wider load regulation range (RF: 0–0.82), enhancing operational flexibility under varying power demands while reducing reformer volume and system cost. Option B significantly improves system efficiency, achieving a peak efficiency of 57.92% after removing water from the ICE fuel. This study provides an efficient and flexible design basis for marine SOFC-ICE hybrid systems.