Multi-scenario assessment of waste heat recovery retrofits in modern passenger ships: A fleet-wide case study

This study presents a comprehensive framework for assessing and enhancing energy efficiency across a fleet of passenger ships through waste heat recovery (WHR) integration. Leveraging operational data from 49 ships of different classes, sizes, ages, and operational locations, typical thermal demand and waste heat availability patterns have been characterized. Six representative scenarios of onboard energy demand have been identified through such analyses, and a scalable thermal demand management strategy has been proposed, considering heat pumps, organic Rankine cycles, and absorption chillers as potential WHR retrofit candidates. The impact of WHR integration has been assessed under varied operating and climatic conditions at both ship and fleet levels. Results show substantial electrical savings by reducing auxiliary boiler use and increasing utilization of recoverable heat. Across the fleet, total WHR improvement potential has been found ranging from approximately 2000 to 33,000 MWh/yr, with corresponding electrical savings up to 186,000 MWh/yr. The findings also highlight significant fleet-wide variability in terms of choice of technology and their impact linked to ship class, size, age, and duty. This emphasizes the need for data-driven retrofit strategies rather than a one-size-fits-all approach. The method and findings from this study provide valuable insights for decision-makers to select optimal technology combinations and deployment strategies to maximize energy efficiency and accelerate maritime decarbonization.