Measurements of air pollution emission factors for marine transportation in SECA

Abstract

Abstract. The chemical composition of the plumes of seagoing ships was measured during a two week long measurement campaign in the port of Rotterdam, Hoek van Holland The Netherlands, in September 2009. Altogether, 497 ships were monitored and a statistical evaluation of emission factors (g kg−1 fuel) was provided. The concerned main atmospheric components were SO2, NO2, NOx and the aerosol particle number. In addition, the elemental and water-soluble ionic composition of the emitted particulate matter was determined. Emission factors were expressed as a function of ship type, power and crankshaft rotational speed. The average SO2 emission factor was found to be roughly half of what is allowed in sulphur emission control areas (16 vs. 30 g kg−1 fuel), and exceedances of this limit were rarely registered. A significant linear relationship was observed between the SO2 and particle number emission factors. The intercept of the regression line, 4.8 × 1015 (kg fuel)−1, gives the average number of particles formed during the burning of 1 kg zero sulphur content fuel, while the slope, 2 × 1018, provides the average number of particles formed with 1 kg sulphur burnt with the fuel. Water-soluble ionic composition analysis of the aerosol samples from the plumes showed that ~144 g of particulate sulphate was emitted from 1 kg sulphur burnt with the fuel. The mass median diameter of sulphate particles estimated from the measurements was ~42 nm.

Field test of available methods to measure remotely SO<sub>x</sub> and NO<sub>x</sub> emissions from ships

“…Partially this can be caused by the fact that also SO 3 and sulphuric acid are formed by the combustion of sulphur containing fuels. During emission studies this has been found to account for between 1 and 8 % of the total sulphur content (Moldanová et al, 2009;Agrawal et al, 2008;Lack et al, 2009;Alföldy et al, 2013). During the SIRENAS-R campaign 7 % of the measured sulphur was present as particle sulphate (Alföldy et al, 2013) and consequently it cannot fully explain the observed difference.…”

“…During emission studies this has been found to account for between 1 and 8 % of the total sulphur content (Moldanová et al, 2009;Agrawal et al, 2008;Lack et al, 2009;Alföldy et al, 2013). During the SIRENAS-R campaign 7 % of the measured sulphur was present as particle sulphate (Alföldy et al, 2013) and consequently it cannot fully explain the observed difference. Thus one possibility is that part of the oxidized sulphur is not being measured because it is deposited before the sampling points; in fact it is known that the acidity of lubrification oil can increase because of sulphur contamination (ABS, 1984).…”

“…Thus the amount of fuel burned at the time of measurement is unknown and has to be estimated by modelling for the calculation of the FSC. Alföldy et al (2013).…”

“…The absolute value of the uncertainty on the FSC (expressed as percent mass of sulphur in the fuel divided by total mass of the fuel) calculated in this way is 0.06 %(m/m), thus corresponding to 6 % relative uncertainty for an FSC of 1 %(m/m) but to 60 % relative uncertainty for an FSC of 0.1 %(m/m). The average relative standard deviation on the determination of FSC values by the "sniffer" method during this campaign was estimated by Alföldy et al (2013) to be 23 % by comparing repeated determinations of emissions from the same ship. The uncertainty on the determination of the NO x emission factor (in g per kg fuel) was found in the same way to be 26 %.…”

“…In the harbour area, these auxiliary engines are likely to give a significant contribution to the overall emissions from the ship. Also the NO x emission factors for Stena Hollandica, relative to power generation (kWh) or to fuel combustion (kg fuel), will depend on the contribution from the auxiliary engines that typically have higher rotational speeds and thus lower NO x emission factors than the main engines (Alföldy et al, 2013) and, in fact, also the few available "sniffer" measurements of NO x were below the on-board stack measurement.…”