Investigation on marine LNG propulsion systems for LNG carriers through an enhanced hybrid decision making model

Abstract

Since the use of LNG as an alternative fuel has drawn increasing attention from the marine industry, this paper aimed to evaluate three competitive LNG fuelled engine systems: ultrasteam turbine, four-stroke medium speed engine, and two-stroke low-speed engine systems. To achieve this goal, the paper developed an enhanced hybrid decision-making model which was applied to integrate the economic, environmental and technical performance of these systems. This model can be represented as a semi-quantitative multi-criteria decision making process in combination of several novel techniques, particularly 'life cycle cost assessment' for economic analysis, 'life cycle assessments' for environmental analysis, 'fuzzy order preference by similarity to ideal solution' for technical analysis and 'fuzzy analytic hierarchy process' for multi-criteria decision making. A case study with a 174K LNG carrier has revealed that the two-stroke low-speed engine system is the most effective overall and suggested that this type of engine system will hold the lead over the other candidates in the large LNG carrier market. It has also demonstrated the effectiveness of the proposed model to improve the inherent subjectivity in existing qualitative multi-criteria decision-making processes by guiding the overall process in a more objective direction. Finally, this paper has revealed an underlying novelty of the proposed model to enhance the level of confidence level in the decision by expanding our short-term perspective to the holistic one.

Development of Parametric Trend Life Cycle Assessment for marine SOx reduction scrubber systems

“…In addition, it is worth noting that this paper does not present emission levels at each life stage of scrubber systems. One of reasons is that a series of past research has demonstrated that the operating phase of the marine systems has the greatest contribution (as high as 99%) to the overall environmental impacts (Jeong et al, 2019). It is because the operating phase has much extensive energy consumption and longer service time compared to construction, maintenance and scrapping.…”

Evaluation of the Lifecycle Environmental Benefits of Full Battery Powered Ships: Comparative Analysis of Marine Diesel and Electricity

“…Considering the primary goal of this LCA research, it adopted the life cycle of energy pathways consisting of the production, the transport and the use stages (see Figure 6). The scope of analysis was not extended to battery or diesel engine products for the reason that a series of previous LCA studies have proven that the environmental impacts relative to manufacturing, installing and recycling of marine products to be negligibly small [7,28,29]. Figure 7 shows the overview of the LCA process for this study.…”

“…(c) Use stageThe use stage describes a way of estimating the emissions associated with the on-board use. For the past maritime LCA research, engine emissions were calculated based on the emission factors provided by the IMO[7,8,28,29,33,34]. It was noticed that such an analytical calculation would probably lead to high discrepancies between the actual and calculated emissions[14,35].…”

Life Cycle Assessment of LNG Fueled Vessel in Domestic Services

“…Hua et al [22] analyzed the total life cycle emissions of a post-Panamax container ship running in both HFO and natural gas. Jeong et al [23] presented the excellence of using LNG-fueled engines based on economic and environmental viewpoints. In the research, the life cycle cost assessment (LCCA) was advised as a useful tool for decision making across industries.…”