Mobile measurements of ship emissions in two harbour areas in Finland

Abstract. Four measurement campaigns were performed in two different environments – inside the harbour areas in the city centre of Helsinki, and along the narrow shipping channel near the city of Turku, Finland – using a mobile laboratory van during winter and summer conditions in 2010–2011. The characteristics of gaseous (CO, CO₂, SO₂, NO, NO₂, NO_x) and particulate (number and volume size distributions as well as PM_2.5) emissions for 11 ships regularly operating on the Baltic Sea were studied to determine the emission parameters. The highest particle concentrations were 1.5 × 10⁶ and 1.6 × 10⁵ cm⁻³ in Helsinki and Turku, respectively, and the particle number size distributions had two modes. The dominating mode peaked at 20–30 nm, and the accumulation mode at 80–100 nm. The majority of the particle mass was volatile, since after heating the sample to 265 °C, the particle volume of the studied ship decreased by around 70%. The emission factors for NO_x varied in the range of 25–100 g (kg fuel)⁻¹, for SO₂ in the range of 2.5–17.0 g (kg fuel)⁻¹, for particle number in the range of (0.32–2.26) × 10¹⁶ # (kg fuel)⁻¹, and for PM_2.5 between 1.0–4.9 g (kg fuel)⁻¹. The ships equipped with SCR (selective catalytic reduction) had the lowest NO_x emissions, whereas the ships with DWI (direct water injection) and HAMs (humid air motors) had the lowest SO₂ emissions but the highest particulate emissions. For all ships, the averaged fuel sulphur contents (FSCs) were less than 1% (by mass) but none of them was below 0.1% which will be the new EU directive starting 1 January 2015 in the SO_x emission control areas; this indicates that ships operating on the Baltic Sea will face large challenges.