Environmental assessment of the scrubbers’ use in regular traffic between the Canary Islands and the Iberian Peninsula

Abstract

The exhaust gas cleaning systems (scrubbers) have proven to be an effective mitigation system for pollutant air emissions. Aside from meeting the current emissions normative (Annex VI of MARPOL 73/78), the scrubbers have resulted in broadly fulfilling the IMO 2015 Guidelines for Exhaust Gas Cleaning Systems (resolution MEPC.259(68)) related to discharge. However, in recent years’ ports have increased restrictions on the use of open-loop scrubbers, as a number of studies have identified deficiencies in the current regulations, especially regarding the limitations of metal concentrations in wash water discharge. This paper quantitatively assesses the overall environmental consequences of open and closed-loop scrubbers’ operation by considering not only air emission reductions, but also the ecotoxicity and eutrophication impact of wash water discharge. Therefore, a pollution cost model is introduced where these concepts are jointly evaluated to calculate the environmental performance of scrubbers. In order to test the model’s effectiveness and to provide quantitative information, the paper analyzes results from an application case for the regular container fleet between the Canary Islands and the Iberian Peninsula.