Methodology for calculating emissions from ships: 2. Emission factors for 2004 reporting

As part of an on-going project to improve the quality of Swedish marine emission reporting, SMED (Swedish Methodology for Environmental Data, a collaboration between the Swedish Environmental Research Institute, Statistics Sweden and the Swedish Meteorological and Hydrological Institute) has derived emission factors for ships (> 100 Gross Register Tonnage). The basis for this type of reporting is that only emissions derived from Swedish sold marine fuels are accounted for. This work presents the agglomerated emissions factors to suit available activity data (i.e. Swedish marine fuel sales) enabling total emissions for the period 1990 – 2002 to be calculated.

When tentatively comparing the new emission totals with those reported earlier (using older emission factor data), a striking difference is that SO2 emissions have been previously underestimated (ca. 5 times too small for International sea traffic). The new HC and CO emissions are however approximately half of those calculated earlier. For NOx, the older estimates agree reasonably well with the new estimates.