Demystifying the lifecycle environmental benefits and harms of LNG as marine fuel

This paper was to answer a fundamental question on whether LNG truly contribute to reducing environmental impacts from shipping activities. Given this, it was intent to determine the holistic association between LNG and environmental impacts. An enhanced method, known as the parametric trend lifecycle assessment, was introduced. To obtain a general observation, the analysis was coupled with the extensive dataset of over 7,000 ships consisting of bulk carriers, container ships, LNG carriers and Ro-Ro ships under various scenarios. Results demystified the environmental strengths and limitations of LNG engines that fell into three representative types: low-speed high-pressure dual-fuel engines, low-speed low-pressure dual-fuel engines, and medium-speed low-pressure dual-fuel engines. The first engine type was confirmed effective compared to diesel fuel, whereas the other two types required further optimization. Research findings also revealed that the operational phase generally contributed twice the global warming effect and about ten times more local pollutants than the production phase. A substantial contribution to the industry could be made by the environmental indicators developed in this paper. They are highly expected to help stakeholders to break through the discrepancy problem raised in previous studies that were so different from case to case that the scope, boundary of analysis, data, and assumptions they used were far away from contributing to standardization. In addition, the proposed approaches taken to develop those indicators are also strongly believed to offer a meaningful insight into future regulatory and decision-making frameworks.