Efficiency evaluation and improvement pathway of sulfur-oxide emissions in European ports based on Context-dependent SBM-DEA model

Sulfur-oxide (SOX) emissions from ports are a crucial environmental concern due to their impact on air quality. European ports, particularly in sulfur emission control areas (ECAs), are under a stringent regulation to reduce SOX emissions; thus, evaluating emission efficiencies and identifying improvement pathways for ports are crucial for developing effective environmental strategies. The research employs a Context-dependent Slack-Based Measure Data Envelopment Analysis (SBM-DEA) model to evaluate the SO(X )emissions efficiency of 70 major European ports from 2006 to 2018 through introducing multi-layered efficiency frontiers to categorize these ports into the efficiency levels and identify specific improvement targets. The results indicate an overall upward trend in the sulfur oxide emission efficiency of European ports, with significant improvements observed from 2006 to 2012. Ports within the North Sea and Baltic Sea, consistently maintain high emission efficiency due to proactive measures like providing shore power and using low-sulfur fuel. However, more than half of the ports still exhibit low efficiency, primarily due to the lack of effective monitoring systems. The study also provides a detailed improvement pathway for the least efficient ports, demonstrating how incremental enhancements can lead to substantial efficiency gains.