Preprints
https://doi.org/10.5194/egusphere-2023-2823
https://doi.org/10.5194/egusphere-2023-2823
12 Feb 2024
 | 12 Feb 2024
Status: this preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).

Local ship speed reduction effect on black carbon emissions measured at remote marine station

Mikko Heikkilä, Krista Luoma, Timo Mäkelä, and Tiia Grönholm

Abstract. Speed restrictions for ships have been introduced locally to reduce the waves and turbulence causing erosion, and safety hazards, and to mitigate the air and underwater noise emissions. Ship speed restrictions could be used to minimise the climate impact of maritime transport since many air pollutants in ship exhaust gas are reduced when travelling at lower speeds. However, for example, methane and black carbon emissions do not linearly correlate with the load of internal combustion engines. Therefore, the effect of speed restrictions may not be trivial. Black carbon concentrations from ship plumes were examined at the remote marine site in the Finnish Southwestern archipelago. Ships with service speeds over 15 knots and equipped with an exhaust gas cleaning system were analysed for black carbon emissions as a function of speed. Both unadjusted and weather-adjusted main engine loads were modelled to determine load-based emission factors. Black carbon concentration per kilogram of fuel decreased as a function of engine load. However, as calculated per hour the black carbon emission increased as a function of ship speed except around a constant emission area, which was roughly 15–20 knots. In terms of local air quality, total black carbon emission per nautical mile was the highest around the halved speeds, 10–13 knots, or when the speed was higher than 20–23 knots. From a climate warming perspective, the CO2 emissions dominated the exhaust gas and reducing the speed decreased the global warming potential in CO2 equivalent both per hour and per nautical mile.

Mikko Heikkilä, Krista Luoma, Timo Mäkelä, and Tiia Grönholm

Status: open (until 30 Mar 2024)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
Mikko Heikkilä, Krista Luoma, Timo Mäkelä, and Tiia Grönholm

Data sets

Local ship speed reduction effect on black carbon emissions measured at remote marine station M. Heikkilä et al. https://doi.org/10.57707/fmi-b2share.b5d1040569394d498d5456435f5a5226

Model code and software

Local ship speed reduction effect on black carbon emissions measured at remote marine station Mikko Heikkilä https://doi.org/10.57707/fmi-b2share.b5d1040569394d498d5456435f5a5226

Mikko Heikkilä, Krista Luoma, Timo Mäkelä, and Tiia Grönholm

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Short summary
Black carbon (BC) concentration was measured from 211 ship exhaust gas plumes at a remote marine station. Emission factors of BC were calculated in grams/kilograms fuel. Ships using exhaust gas cleaning systems (EGCS) were found to emit 80 % less BC than ships without EGCS. Emission factors were used to model BC emissions as a function of speed to define the effect of speed reduction. BC emissions increased with a decrease in speed from the ship’s service speed.