Investigation of BOG management during marine LNG transport focusing on its use for ship propulsion

Abstract

This thesis is aimed firstly at comparing BOG utilization as fuel by different vessel propulsion plants and secondly by proposing a BOG management method for said propulsion plant arrangements. Maritime LNG transport is the way one of the largest quantities of LNG are transported, due to the BOG generated though, quantity of the cargo is wasted. The purpose of this thesis is to analyze the natural gas history, highlight its maritime transport and the BOG problem, examine the different propulsion plants and compare how each one differs and utilizes the BOG. How this is going to be achieved is by setting up a virtual case study vessel and deciding which propulsion plant system arrangements are interesting in comparing to one another. After that, the BOG rate for the case study vessel size will be estimated using at least two different methods. Following BOG supply calculations, the propulsion plant energy and thus BOG supply demands will be calculated. It will be found that the BOG in most cases is more than enough to supply the vessel’s fuel needs. Lastly, a way to treat the excess BOG and some calculations evaluating its effectiveness will be conducted. The whole procedure of gathering the information and specific characteristics will result in an easy comparison between the chosen propulsion plants and possible BOG treatment methods. Concluding, key takeaways will be pinpointed and future research ideas will be given.