Comprehensive techno-economic assessment of SOFC hybrid system in marine applications: A carbon emission framework perspective

This study investigates the techno-economic feasibility of a hybrid electric propulsion system that integrates solid oxide fuel cells (SOFC), energy storage systems (ESS), and dual fuel generators (DF Gen) for large commercial vessels. A 20-year operational analysis was conducted using 500 h load profiles from a 174,000 m³ liquefied natural gas (LNG) carrier. Carbon dioxide (CO 2 ) emissions and total cost of ownership (TCO) were assessed under varying SOFC capital costs, carbon tax levels, and fuel prices within a full carbon life-cycle framework. Unlike conventional approaches that consider only Tank-to-Wake (TTW) emissions, this study adopts a Well-to-Wake (WTW) and CO 2 -equivalent perspective to comprehensively evaluate greenhouse gas impacts. The results show that the SOFC + ESS hybrid system improves electrical efficiency and achieves CO 2 emission reductions of up to 3 % compared with conventional mechanical propulsion systems under TTW conditions. When the analysis expands to include WTW CO 2 -equivalent emissions based on a 20-year global warming potential (GWP20), the reduction reaches approximately 30 %. Economic competitiveness is sensitive to multiple parameters, including SOFC capital cost, carbon tax level, and fuel price, and the hybrid system becomes favorable under scenarios with higher carbon tax or reduced SOFC investment cost. Although the SOFC hybrid cannot fully meet the International Maritime Organization (IMO) 2050 decarbonization target when operated on fossil fuels alone, it represents a promising transitional technology—particularly when combined with carbon capture or carbon-neutral fuels such as ammonia or hydrogen. • A hybrid marine propulsion system integrating SOFC, ESS, and DF Gen is evaluated. • Life-cycle CO 2-eq emissions are analyzed under current and future regulatory frameworks. • The SOFC system becomes cost-effective with rising carbon tax and LNG prices. • Full CO 2-eq evaluation shows SOFC systems reduce emissions vs. conventional engines. • SOFC hybrid systems are promising for IMO goals when paired with CCS or green fuels.