Alternatives for internal combustion engine waste heat recovery in electric RoPax ferries

Abstract

Driven by increasingly stringent emissions regulations by the IMO to become net zero by 2050, electrification is being viewed as an attractive alternative to the traditional and modern maritime fuels. However, electrification presents unique challenges of its own, the loss of waste heat recovery (WHR) due to the elimination of combustion engine. Traditionally, WHR compensated for 70% of the heating demand and thus with electrification the battery must now supply all the heating load, increasing battery strain and operational complexity. The thesis provides a methodology to find an economically viable, energy efficient and environmentally responsible solution. It develops a structured flux-based modelling approach to quantify the thermal loads of a representative electric RoPax vessel. It provides a range of alternative heating solutions such as heat pumps, district heating integration, thermal energy storage and waste heat recovery from batteries and greywater. The solutions are then systematically evaluated based on economics, battery strain and emission reductions using Viking Line XPRS as a case vessel.

Comparative analysis shows that advanced heat pump systems, especially combined with selective ventilation or shore-side support can reduce battery strain up to 35-60% (seasonal dependency). All proposed solutions eliminate operational greenhouse gas emissions when supplied with renewable sources. The results confirm that no single strategy provides a complete solution, instead, a combination of efficient heating systems and smart integration strategies is necessary to meet both economic and environmental goals. The methodology and findings offer actionable guidance for ship designers and operators as the maritime industry moves towards energy-efficient and low-emission vessel operations.