Given that using LNG as a marine fuel has increasingly drawn more and more attraction from the marine industry, this paper was aimed to evaluate the optimal selection of three credible LNG engine systems by identifying environmental perspective; they are ultra steam turbine, four-stroke medium speed engine, and two-stroke low speed engine systems. To achieve this goal, this study has chosen one of the various novel techniques as life cycle assessment using software ‘Gabi.’ Research findings from a case study with a 174K LNG carrier have revealed that two-stroke low speed engine systems are the most effective overall, suggesting that this type of engine systems will hold a lead over the other candidates in the-not-too distance future. This paper has finally presented an underlying novelty of the proposed model that could extend our short-term view to the long-term one. Therefore, the impact of the proposed model was strongly believed to be extensive and remarkable to various studies which need proper decision-makings, not necessarily limited to the marine systems.