Carbon dioxide liquefaction and transport optimization for marine carbon sequestration: A comprehensive review

As global demand to reduce carbon emissions intensity, the liquefaction and transportation stages of ocean-based CO 2 sequestration have become major bottlenecks in system energy consumption and overall economic feasibility. This review develops an integrated analytical framework to examine optimization strategies for CO 2 liquefaction and transportation. It synthesizes progress in multi-stage liquefaction cycle structures, alternative working fluid, and thermodynamic integration schemes, and compares the performance, energy consumption, safety, and application scenarios of liquid (LCO 2 ), gaseous (GCO 2 ), and solid (SCO 2 ) transportation modes. The review also evaluates advances in boil-off gas management, including onboard reliquefaction, ammonia refrigeration, and hybrid refrigeration cycles, and highlights the synergistic use of LNG cold energy, industrial waste heat, and solar energy. Furthermore, emerging operational approaches such as multi-objective optimization and AI-enabled predictive control are assessed for their potential to enhance adaptability and dynamic system stability. Across the literature, the review identifies consistent trends toward multi-energy gradient utilization, modular integration, and intelligent scheduling, while also highlighting gaps in full-chain techno-economic assessment and large-scale demonstration data. Overall, the findings provide a structured understanding of current technologies and outline key research directions to support the large-scale deployment of CO 2 ocean sequestration.