Sources of air pollutants from a Tier 2 ocean-going container vessel: Main engine, auxiliary engine, and auxiliary boiler

Abstract This study assessed the gaseous and particulate emissions from a Tier 2 oceangoing vessel using two emission control area (ECA) compliant fuels, a very low sulfur marine gasoil (MGO) and a novel ultra-low sulfur heavy fuel oil (ULSHFO). In-use emissions are reported for the main engine when the ship traveled in within California's ECA, whereas emissions for the auxiliary engine and boiler are presented when the ship was at-berth in the port of Long Beach. For the auxiliary boiler, emissions of carbonyl compounds and metallic elements were also characterized. The ULSHFO showed higher nitrogen oxide (NOx) emissions than MGO for both the main and auxiliary engines, but not at statistically significant levels, whereas for the auxiliary boiler the ULSHFO showed statistically significant increases in NOx emissions compared to MGO. NOx emissions for this vessel's main and auxiliary engines were within the certification limits for both fuels. Particulate matter (PM2.5) and black carbon emissions were higher for the ULSHFO and decreased with higher engine load conditions. The main engine PM2.5 composition was dominated by organic carbon and the auxiliary engine PM composition was primarily comprised of elemental carbon. For both engines, there was little contribution of sulfate due to the very low sulfur content in both fuels. Formaldehyde and acetaldehyde were the major aldehyde species in boiler exhaust. Sulfur, vanadium, and iron were the most abundant elements detected in PM2.5 emissions. Overall, this work demonstrated the potential global benefit of using ultra-low sulfur residual fuels, however, their use near ports will likely increase local emissions compared to middle distillate fuels.