Advancing greener LNG-fueled vessels: Compact simultaneous reduction system for CH₄, NO_X and CO₂ emissions

Stringent ship regulations necessitate simultaneous emission reductions, challenged by cargo loss and energy constraints. This study proposes a compact reduction system that simultaneously mitigate CH₄, NO_X, and CO₂ emissions onboard LNG-fueled vessels. The proposed system integrates two pivotal technologies: a metal support-based compact methane oxidation catalyst (MOC)-selective catalytic reduction (SCR) system to capture CH₄ and NO_X, and a cryogenic CO₂ capture (CCC) system to capture and store CO₂ in its solid phase utilizing LNG's cold energy. This innovative approach addresses two challenges. First, the compact MOC-SCR system employs metal support with an enhanced surface area-to-volume ratio surpassing the capabilities of ceramic support materials, achieving a volume reduction of 80.02% and 79.82% respectively. Secondly, the CCC system significantly lowers specific energy consumption by 61.54% by harnessing LNG's cold energy compared to the absorption-based CO₂ capture system. As a result, the proposed system not only reduces CH₄, NO_X, and CO₂ emissions simultaneously with a high capture rate but also reduces volume and weight. Furthermore, it achieves a high CO₂ capture rate of 92.12%, while diminishing cargo losses by 25.30%. These findings provide valuable guidance for developing environmentally sustainable vessels, aligning with the continuously increasing stringency of regulations.