Comparative Analysis of Different On-Board CCS Molten Carbonate Fuel Cell Solutions for IMO Compliance

Abstract

This study analysed the use of a CCS system on board ships to reduce CO₂ emissions, in line with the new maritime regulations issued by the International Maritime Organisation (IMO). To achieve the desired removal rates, two innovative plant configurations were investigated: the first approach uses a traditional reforming reactor (thermally heated steam methane reformer [tSMR]) heated with burners, whereas the second employs an electrified reforming reactor (electrically heated steam methane reformer [eSMR]). The two solutions were compared considering fuel consumption, system footprint, simplicity of implementation, the ratio between liquefied CO₂ and removed CO₂, and thermal integration, which are crucial parameters for integrating a CCS system on board ships. Simulation results showed that the eSMR system offers significant advantages in terms of footprint, design simplicity and thermal integration. However, the tSMR system exhibits greater efficiency in liquefied CO₂ storage and fuel consumption reduction for engines running on HFO with a specific fuel oil consumption (SFOC) of approximately 180 g/kWh. Additionally, it has a smaller footprint at low CO₂ removal rates. Consequently, the optimal solution depends on several factors, including the type of vessel (short- or long-range routes), engine characteristics and specific fuel consumption, the type of fuel used and the CO₂ reduction target. In conclusion, both solutions demonstrate superior performance compared to traditional systems described in the literature.