Potential of liquefied natural gas cold energy recovery on board ships

Liquefied natural gas is stored on board vessels under cryogenic conditions, and hence, fuel preheating is required before injection in the engine. The cooling effect associated with this preheating phase can be utilized to decrease the vessel’s overall fuel consumption. Previous works focused on evaluating the prospects for cold energy recovery for specific applications, but failed to provide a detailed overview of the potential uses of liquefied natural gas cold energy recovery on board ships. The objective of this paper is to provide a detailed overview of the potential uses of liquefied natural gas cold energy recovery on board ships, including discussing their prospects in terms of fuel savings and constraints. The evaluations are based on the use of validated numerical models and are carried out for two reference vessels: a ferry featuring a low pressure fuel supply system, and a long-distance containership featuring a high pressure fuel supply system. The results of the study indicate that the greatest fuel savings can be attained when the vessel is powered by a low pressure fuel supply system, reaching up to 2.4%, and that the most promising solution for recovering the cold energy is its use in the organic Rankine cycle unit. The findings of this work provide the scientific basis needed for further research work and the subsequent commercialization of installations of cold energy recovery on ships.