Organic Rankine cycle-based waste heat recovery system combined with thermal energy storage for emission-free power generation on ships during harbor stays

The pollutant emissions from ships in harbor are a pressing concern due to their direct impact on the health of the population. The use of electric-battery propulsion is a viable solution to reduce the emissions in coastal areas, but it is only applicable to small ferries. Large cruise ships commonly utilize shore power connection to provide onboard electricity, avoiding pollution during harbor stays. However, this solution is not applicable during short stays. This paper presents a novel and energy-efficient way to supply zero-emission power during harbor stays of marine vessels. The proposed system combines the use of a thermal energy storage and a waste heat recovery system based on the organic Rankine cycle technology. The objective of this work is to investigate the technical feasibility of the proposed system and to compare its cost-effectiveness with the alternative solution of using batteries during harbor stays. The study is based on a case study of a hypothetical ferry requiring 1 MW of auxiliary power during harbor stays. The results suggest that the proposed system would require the installation of a storage tank of around 82 m3, and that it could be economically competitive with the battery-based solution, especially when considering its installation on newly built ships. Lastly, it is estimated that the installation of the proposed concept would lead to reduction of the ferry’s carbon dioxide emissions by 8%.