Utilizing the thermal energy from natural gas engines and the cold energy of liquid natural gas to satisfy the heat, power, and cooling demands of carbon capture and storage in maritime decarbonization: engineering, enhancement, and 4E analysis

The MEPC 80 session has revised the International Maritime Organization (IMO) greenhouse gas strategy, setting more ambitious decarbonization goals. Carbon capture and storage (CCS) technologies have shown promise in reducing maritime carbon emissions, although their high-energy requirements have often been neglected in previous research. This study introduces a novel system integrating a natural gas engine, CCS, an Organic Rankine Cycle (ORC), and a power turbine (PT). An exhaust gas bypass strategy is used to enhance engine performance at low and medium loads, channeling exhaust to the PT for power generation. The engine's waste heat is fully utilized for CCS via cold, heat, and power. The study compares various absorbents in the CCS system, including monoethanolamine and piperazine solutions, which show different carbon capture efficiencies. Additionally, CO2 storage conditions are analyzed and compared. The proposed system shows potential for significantly reducing the Energy Efficiency Design Index for general cargo ships. The study addresses the high-energy demands of CCS by utilizing the engine's waste heat, transforming a potential drawback into a beneficial resource. By integrating the ORC and PT, the system not only captures carbon but also improves overall energy efficiency, presenting a promising solution for maritime decarbonization. The analysis of CO2 storage conditions further enhances the understanding of effective carbon management. This innovative system demonstrates that with strategic integration and optimization, significant progress can be made toward achieving the stricter decarbonization targets set by the IMO while also enhancing the energy efficiency of maritime operations.