Techno-Economic and Environmental Assessment of an ORC-Based Waste Heat Recovery and Cold Ironing System for an Offshore Platform Supply Vessel

The maritime industry is under increasing pressure to comply with International Maritime Organization (IMO) regulations targeting net-zero greenhouse gas emissions by 2050.This study evaluates an Organic Rankine Cycle (ORC)-based waste heat recovery system integrated into an offshore platform supply vessel, explicitly considering four distinct operating modes: cruising, dynamic positioning, standby, and port.A steadystate thermodynamic ORC model developed in MATLAB is employed to represent average operating conditions in each mode.Among the ten candidate working fluids, R1233zd(E) is identified as optimal, delivering a net power output of 192.74 kW at full engine load.Four energy management scenarios are examined: a conventional baseline, integration of an ORC, an ORC-battery hybrid system, and an ORC system combined with cold ironing during port operations.The results indicate that the ORC-cold ironing configuration achieves the highest environmental benefit, reducing total cycle-level CO 2-eq emissions by approximately 26.7% relative to the baseline case.From an economic perspective, direct ORC integration yields the lowest levelized cost of energy of $0.1481/kWh and a discounted payback period of 6.27 years, while the ORC-cold ironing configuration has a payback period of 7.70 years.Sensitivity analysis demonstrates that fuel price escalation and carbon taxation are the dominant drivers affecting economic feasibility.