Modeling and dynamic optimization strategy for the thermo-electric-carbon coupling of onboard carbon capture system

Objective To comply with increasingly stringent carbon emission regulations in the shipping industry and achieve efficient and cost-effective decarbonization of ship exhaust gases, this study investigates the energy efficiency, economic performance, and operational optimization of onboard carbon capture systems (OCCS).

Method Using a 14000 TEU container ship as the case study, a thermo-electric-carbon coupled energy-mass flow model covering the main engine, auxiliary engine, boiler and OCCS was developed in Simulink. The operational response characteristics of the amine-based carbon capture process were analyzed through fixed-point steady-state simulations and historical voyage simulations, and its economic competitiveness was quantitatively evaluated. A dynamic capture-rate optimization strategy based on main engine load intervals was proposed. The optimization problem was solved using a hybrid RTPSO-PS (Ring Topology Particle Swarm Optimization-Pattern Search) algorithm.

Results The developed model satisfies the accuracy requirements for engineering applications. The specific energy consumption for carbon capture is non-uniformly distributed. At the target capture rate of 40%, the additional voyage fuel consumption attributable to the thermal and electrical loads accounts for approximately 12% and 2.5% of the main engine fuel consumption, respectively, and the net emission reduction performance satisfies the phased decarbonization requirements established by IMO. Under the EU Emissions Trading System (EU ETS), the system payback period is approximately 3.7 years, and its economic performance is significantly superior to that of an LNG retrofit solution. The proposed differentiated capture-rate optimization strategy can simultaneously improve the voyage decarbonization benefits and regulatory compliance, while the RTPSO-PS algorithm demonstrates robust optimization performance.

Conclusion The OCCS possesses excellent technical and economic feasibility. The proposed coupling model and dynamic optimization strategy can provide theoretical support for engineering applications.