Lower NO_x but higher particle and black carbon emissions from renewable diesel compared to ultra low sulfur diesel in at-sea operations of a research vessel

Abstract

Gas and particle emissions from R/V Robert Gordon Sproul were measured for ultra low sulfur diesel (ULSD) and hydrogenation derived renewable diesel (HDRD) during dedicated aerosol measurement cruises in 2014 (29 September-3 October) and 2015 (4-7 and 26-28 September). CO, CO 2 , and NO X were measured directly from the starboard stack from the 2-stroke, small bore, high speed engine, while number and mass size distributions for both particles and black carbon (BC) were measured by intercepting the ship plume. Measurements at constant engine speeds (1600 rpm, 1300 rpm, 1000 rpm, and 700 rpm) had emission factors of CO (EF CO ) and NO X EF NOX ð Þ that were lower by 20% and 13%, respectively, for HDRD compared to ULSD at 700 rpm. However, at 1600 rpm, EF CO and EF NOX were within one standard deviation for both ULSD (EF CO : 4.0 § 0.1 g [kg-fuel] ¡1 ; EF NOX : 51 § 0.8 g [kg-fuel] ¡1 ) and HDRD (EF CO : 3.9 § 0.2 g [kg-fuel] ¡1 ; EF NOX : 51 § 2 g [kg-fuel] ¡1 ). HDRD emission factors of particle number and mass concentrations were higher than ULSD by 46% to 107% and 36% to 150%, respectively, at 1600, 1300, and 1000 rpm, but the differences were smaller than the cycle-to-cycle variability at 700 rpm. BC mass emission factors were nearly 200% larger for 700, 1000, and 1300 rpm for HDRD compared to ULSD, but the mass differences were smaller than cycle-to-cycle variability at 1600 rpm. BC mass size distributions showed that the peak diameter of the BC mass mode for ULSD (»120 nm) is about 20 nm larger than for HDRD (»100 nm), even though the particle mass and number size distributions are quite similar.

Hydroxyl radical formation and soluble trace metal content in particulate matter from renewable diesel and ultra low sulfur diesel in at-sea operations of a research vessel

“…OH production normalized to kilograms of fuel burned is shown in Figure 1b. Values are shown only for 2015, as in 2014 stack sample CO 2 measurements were not available due to instrument problems (Betha et al 2017). Consistent with the observation that PM mass emissions were higher for HDRD than ULSD (Betha et al 2017), once normalized to fuel burned, the differences between 2015 ULSD and HDRD OH generation activity is larger than the PM-mass normalized data.…”

“…The results indicate a large fraction of OH generation is controlled by soluble redox-active transition metals, Total "Metals" includes 13 metals and Se, but was dominated by Mg, Ca, and Zn (Table S2). BC mass concentrations in all 2014 samples were measured with an Aethalometer (Paulson et al 2016) and BC mass concentrations in 2015 samples were measured with an SP2 (Betha et al 2017).…”

“…Since the ship was not equipped with an engine dynamometer, sampling was conducted at four engine speeds (1600 rpm, 1300 rpm, 1000 rpm, 700 rpm). Nonetheless, emissions at any engine speed did vary with sea state and other conditions (Betha et al 2017). Simultaneous measurements of gas and particle emissions are described in companion papers (Betha et al 2017;Price et al 2017).…”

“…Simultaneous measurements of particle and gas mass emission and chemical composition and concentrations are reported in two companion papers (Betha et al 2017;Price et al 2017). Betha et al (2017) showed that emission factors for CO and NO x were higher for ULSD than HDRD, and EFs decreased with increasing engine speed. Different trends were observed for black carbon and particle number, with higher number and mass emission factors for HDRD.…”

Ship plumes in the Baltic Sea Sulphur Emission Control Area: Chemical characterization and contribution to coastal aerosol concentrations

“…Most particles emitted from ships are in the sub-micrometre range, typically with a diameter below 100 nm (Lack et al, 25 2009). Studies have shown a decrease in mean particle diameter when switching to a lower fuel sulphur content (Betha et al, 2017;Zetterdahl et al, 2016) as well as a decrease in emitted particulate matter (PM) (Lack et al, 2009;Diesch et al, 2013;Mueller et al, 2015;. The International Maritime Organization (IMO) have regulated fuel sulphur content in several steps in recent years, from 1.5% to 0.1% mass fraction between the years 2010 and 2015 in sulphur emission control areas (SECA).…”