Analysis and measurement of SOx, CO2, PM and NOx emissions in port auxiliary vessels.

The objective of this paper is to provide an estimation of air emissions (CO2, NOx, SOx and PM) released by port assistant vessels at port level. The methodology is based on the "full bottom-up" approach and starts by assessing the fuel consumed by each tug ship during its individual port exercises (movements during docking and undocking of merchant vessels). The scenario selected for the analysis and measurements is one of the most significant Port of the Mediterranean Sea, where seven auxiliary vessels were monitored for 407 calls. The analysis also gathers real-time data from the Automatic ship Identification System (AIS), tug ship particulars from IHS sea-web database ( www.maritime.ihs.com ) and emission factors established by the International Maritime Organization (IMO). The research findings show that the key indicators are inventory emissions per dock, types of towed vessels and docking and undocking manoeuvres. This paper also presents an action protocol for the assessment of the inventory of emissions produced by the main engines of tug ships operating inside ports, which can be extrapolated to other ports operating with tug ships of the same technical characteristics. Evaluating, therefore, the amounts emitted of nitrogen oxides, sulphur oxides, carbon dioxide and particulate matter.