Fuzzy Multi-Objective Ranking of Scenarios/Technologies Aiming at Reduction of SOx Emissions by Ships

Abstract: This work deals with multiobjective ranking of scenarios/technologies aiming at reduction of SOx (Sulphur Oxides) emissions by ships. Initially, It is proved that there is a continuum between alternative scenarios/technologies rather than candidate distinct solutions, recognized as such on an a priori basis. Subsequently, a methodological framework under the form of an algorithmic procedure is presented, where a multicriteria tool is embedded by using six criteria, namely economic cost, environmental cost, reliability in performance, flexibility/adaptability, technology maturity, and technology perspective. The available scenarios/technologies have been categorized to form the following seven quasi-distinct alternatives within an a(i,j) 6×7 preference matrix: mixed hybrid fuel, A1; marine gas oil, A2; liquefied natural gas, A3; modified fuel cell, A4; dry scrubber technology, A5; hybrid wet scrubber based on NaOH, A6; hybrid wet scrubber based on MgO, A7. Fuzzy values were assigned to the matrix elements in fuzzy triangular form by means of a modified Delphi method to count for uncertainty. The matrix solution gives the ranking A3 > A1 > A2 > A7 > A6 > A5 > A4, where the symbol '>’ stands for 'better than’. Sensitivity/robustness analysis is performed, the results obtained and the assumptions made are discussed, remarks for specialization of multi-criteria analysis are presented, and directions for further research are suggested.