Process design and optimization of PEMFC-methanol engine hybrid propulsion system with life cycle assessment

With increasing environmental regulations from the International Maritime Organization and the Environmental Protection Agency, the transition to low carbon alternatives to fossil fuels has become a significant challenge for the maritime industry. Methanol has emerged as a promising low carbon fuel due to its liquid state at ambient conditions and compatibility with existing infrastructure. However, the carbon content of methanol raises concerns about its long-term carbon neutrality. In this study, we proposed a hybrid system by integrating a methanol fueled internal combustion engine with a polymer electrolyte membrane fuel cell and a methanol recycling process including carbon capture and resynthesis. The entire system was modeled using Honeywell UniSim Design and evaluated under container ship conditions for a single voyage through a life cycle assessment. The simulation and LCA results showed that the hybrid configuration significantly reduces CO2 emissions compared to a conventional methanol only engine. Under optimal operating conditions, the methanol conversion rate reached 60.17 %, enabling effective CO2 recycling. This study confirms the technical feasibility and environmental potential of methanol as a bridge fuel and provides a quantitative basis for decision making on sustainable marine fuel strategies in line with international regulatory targets.