Selecting technological alternatives for regulatory compliance towards emissions reduction from shipping: An integrated fuzzy multi-criteria decision-making approach under vague environment

Due to the increasing pressure from stricter environmental regulations to reduce emissions in shipping, the maritime industry has been striving for finding more effective measures. Existing measures are often not enough to comply with new regulations. Among various alternative measures, it is not easy for decision-makers (shipowners and operators) to choose the most suitable alternative measure as it involves with multi-criteria decision-making where the prioritization of a number of alternatives vis-à-vis multiple criteria evaluation is undertaken. Further challenges on such analysis are the lack of information as well as its subjectivity and/or the inconsistency. This study proposes an integrative fuzzy multi-criteria decision-making method that combines fuzzy analytic hierarchy process (AHP) and fuzzy technique for order performance by similarity to ideal solution (TOPSIS) for the selection of technological alternatives for regulatory compliance under vague environment. Nine criteria within three sustainability aspects (social, economic and environmental aspects) were analysed and evaluated as regards four possible alternatives. The weights of these aspects and criteria were determined by the fuzzy AHP; meanwhile, alternatives were prioritized by the fuzzy TOPSIS. According to the outputs of the proposed decision-making framework, the study revealed that low-sulphur fuels are the best suitable alternative for regulatory compliance. The following alternatives are methanol, scrubbers and liquefied natural gas in order. Sensitivity analysis was conducted to tell us that the proposed framework is robust. This proposed method will be potentially applicable to other fields where decisions are required to make under vague information conditions.