Emissions of NO, NO₂ and PM from inland shipping

Abstract. Particulate matter (PM) and nitrogen oxides NO_x (NO_x =  NO₂+ NO) are key species for urban air quality in Europe and are emitted by mobile sources. According to European recommendations, a significant fraction of road freight should be shifted to waterborne transport in the future. In order to better consider this emission change pattern in future emission inventories, in the present study inland water transport emissions of NO_x, CO₂ and PM were investigated under real world conditions on the river Rhine, Germany, in 2013. An average NO₂ ∕ NO_x emission ratio of 0.08 ± 0.02 was obtained, which is indicative of ship diesel engines without exhaust gas aftertreatment systems. For all measured motor ship types and operation conditions, overall weighted average emission indices (EIs), as emitted mass of pollutant per kg burnt fuel of EI_NOx =  54 ± 4 g kg⁻¹ and a lower limit EI_PM1 ≥  2.0 ± 0.3 g kg⁻¹, were obtained. EIs for NO_x and PM₁ were found to be in the range of 20–161 and  ≥  0.2–8.1 g kg⁻¹ respectively. A comparison with threshold values of national German guidelines shows that the NO_x emissions of all investigated motor ship types are above the threshold values, while the obtained lower limit PM₁ emissions are just under. To reduce NO_x emissions to acceptable values, implementation of exhaust gas aftertreatment systems is recommended.