In-depth characterization of exhaust particles performed on-board a modern cruise ship applying a scrubber

• Published in: The Science of the total environment Vol. 946; p. 174052
• Main Authors: Kuittinen, N., Timonen, H., Karjalainen, P., Murtonen, T., Vesala, H., Bloss, M., Honkanen, M., Lehtoranta, K., Aakko-Saksa, P., Rönkkö, T.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 10.10.2024
• Subjects: Exhaust aerosol; Marine engine; Particle emissions; SCR; Scrubber; Particle emissions; Scrubber; Exhaust aerosol; SCR; Marine engine
• DOI: 10.1016/j.scitotenv.2024.174052
• ISSN: 0048-9697; 1879-1026

To comply with environmental regulations, ship operators may adopt exhaust after-treatment devices such as scrubbers or selective catalytic reduction (SCR). Beyond gaseous emission control, these technologies impact the exhaust particles emitted from marine engines to the atmosphere. This study characterizes comprehensively the chemical composition and physical properties of exhaust aerosol particles upstream and downstream a hybrid scrubber operating in open loop mode on-board a modern cruise ship. The study considers two engines, one equipped with SCR and both with scrubber, during engine load conditions of 75 % and 40 %, and the influence of marine gas oil (MGO) use in addition to heavy fuel oil (HFO). At least 4 different particle types were observed in the exhaust based on transmission electron microscopy (TEM) studies both upstream and downstream scrubber, and both scrubber and SCR affected the particle number size distribution (PSD). The geometric mean diameter (GMD) of the particles increased over scrubber both due to removal of nucleation mode particles and particle growth in the scrubber. The scrubber effectively decreased particle number (PN) and, also, non-volatile particles, but the effect depended on particle size and no significant decrease was observed in number of particles above 50 nm, typically comprising black carbon (BC) and in the case of HFO combustion, also asymmetrical metal containing particles. In addition to PN, concentrations of PAH compounds were reduced in the scrubber. The results may be further utilized when including the exhaust aerosol characteristics from ships applying scrubbers to emission inventories, as well as climate and air quality models. [Display omitted] •Increasing number of sulfur scrubbers also affect the exhaust particle emissions.•Particle properties comprehensively characterized on-board a modern cruise ship•Particle number and PAH compounds reduced by scrubber and SCR•Several characterized particle types in the exhaust also downstream scrubber•Scrubber effects to be considered in emission mitigation and inventories