Abatement of particulate matter and SO2 emission by ships

Ship engines emit noxious gases (SO2, NOx, and VOC) and particulate matter (PM), mostly black carbon. Since 1990, the International Maritime Organization (IMO) regulations gradually restricted the level of emission of NOx, which since 2016 have to be lower than 2-3.4 g/kWh, depending on engine power. SO2 emission reduction has begun since 2010 and now the content of sulphur in marine fuels is limited to 3.5%. At the same time, the Sulphur Emission Control Areas (SECA) has been established, at which the sulphur content in fuel cannot be higher than 0.1%. Since 2020, only a fuel of 0.5% sulphur can be used at all cruising areas outside SECA. It should be noted that due to lack of efficient technology, IMO still has not issued regulations regarding the PM emission by ships. The paper discusses various electrostatic techniques used for the reduction of PM emission in Diesel engine exhausts. Electrostatic scrubber systems, using seawater, allow removal of PM from exhausts with high efficiency and simultaneously SO2 gas. Electrostatic agglomerators allow increasing submicron and nanoparticles by coagulation of those particles to the larger ones, which could be removed by conventional techniques.