Optimal Solutions for container ship alternative fuels under EU ETS: a comprehensive evaluation based on entropy weight-TOPSIS-grey relational analysis

Against the backdrop of intensifying carbon emission reduction pressures in the international shipping industry and the gradual implementation of the EU ETS and FuelEU policies, the selection of alternative fuels for ships has become a key issue affecting shipping companies’ operational costs and emission reduction performance. This paper takes a 20, 000 TEU container ship on the Asia-Europe route as the research object, constructs a multi-level evaluation index system covering technical parameters, cost parameters, and emission parameters, and selects four fuel options—VLSFO, LNG, methanol, and ammonia—for comparative analysis. In terms of methodology, the entropy weight method is used to determine indicator weights to enhance the objectivity of weight allocation. This is combined with the TOPSIS-grey relational analysis method to construct a comprehensive evaluation model, ranking the advantages and disadvantages of different fuel options. The robustness of the model results is tested through sensitivity analysis. The research results indicate that the LNG option achieves the optimal balance among technological maturity, operational economy, and emission reduction effects, making it the optimal choice at the current stage. The ammonia option has outstanding zero-carbon potential but faces high retrofit costs, limiting its application in the short term, and its comprehensive performance follows closely behind. Traditional VLSFO faces serious compliance risks, while the methanol option is less competitive due to infrastructure constraints. The comprehensive evaluation method constructed in this paper has strong applicability and reliability, providing theoretical support and practical reference for shipping companies in making alternative fuel decisions under the constraints of the EU ETS.