A Preliminary Study on the Application of Thermal Storage to Merchant Ships

The shipping industry is focusing more and more on reducing fuel consumption and greenhouse gas emissions. A non-negligible amount of fuel is consumed while ships are in port, waiting for loading or unloading, for heating up accommodation spaces and fuel tanks, while when at sea waste heat from engines exhaust is under-used because of low demand. In this paper we propose the use of thermal energy storage as a solution for the mismatch between heat availability and demand. A simplified system is proposed and the influence of design parameters (storage size, heat exchangers surface, secondary fluid mass flow rate, storage temperature) on the performance of the system is analyzed. The results of the application of a thermal energy storage system to a case study ship show that the installation of a storage tank of 1000 m3 could reduce the fuel consumption from the boilers by 80%, which would lead to yearly savings of 268,000 USD. This preliminary analysis shows that there is potential of both economic and environmental benefits from the application of thermal energy storage to merchant vessels.