An early-stage approach to optimise a marine energy system for liquefied natural gas carriers: Part B — Application

The present work aims to provide a comprehensive early-stage approach to optimise the design, synthesis and operation of a marine energy system for liquified gas carriers, considering their economic and technical aspects, and also weather along the route. Part A of this work details the approach that we have developed while Part B will summarise the first part, it will then describe the case study, results and discussion, as well as the conclusion. Various propellers, 16 engines and 4 operational profiles are assessed. In this part, we will apply a differential evolution optimisation algorithm, whose objective function will be maximised as the net present value. The case study is designed to use a liquefied natural gas carrier of 175,000 m3 sailing between Lake Charles (USA) and Tokyo Bay (Japan), via the Panama Canal. All of the suitable matchings for 15,023 propellers are found. This approach shows a gain of 22% between the worst individual of the initial population and the worst individual of the final population. The required brake power is approximately 22% higher for rough weather than for still water. A difference of over 120% was found by comparing varied matchings of economic scenarios and fuel profiles. Our approach shows a significant gain and highlights the value of exploring a broad range of energy system configurations in an integrated manner, especially considering the weather conditions.