A submission by Finland and Germany to the IMO’s Pollution Prevention and Response (PPR) sub-committee includes the findings of a recent report which are said to ‘clearly indicate’ that new IMO 2020-compliant 0.50% sulphur fuel blends contain high aromatic compound levels, which can directly impact on black carbon (BC) emissions.
The Marine Environment and Protection Committee (MEPC) 62 originally instructed the Sub-Committee on Bulk Liquids and Gases (now PPR) to develop a definition of BC in relation to its impact on the Arctic environment. At MEPC 74, some delegations also noted that the recommended BC measurement methods needed further work to achieve convergence of results and it was also suggested that the impact of the 0.50% global sulphur limited needed to be taken into account.
Subsequently, Germany has undertaken a BC measurement campaign using two out of the three accepted BC measurement methods (FSN and PAS) to look at the impact of different fuel oil qualities on BC emissions.
The campaign, funded by the German Environment Agency, was undertaken by WTZ Roßlau with input from MAN ES, DNV GL and Marena Lt
A comparison was made between the BC emissions of 0.50% hybrid fuels and HFO and DMA, and also a synthetic Gas to Liquid (GtL) fuel, using varying engine ratings on a test bed.
The 0.50% fuels were said to be have been sourced from possible sample mixtures from refinery streams most likely to be used in 2020.
None of 0.50% fuels showed any reduction in BC emissions compared to HFO, but there was a reduction in the emissions of conventional DMA grade distillate and particularly the GtL fuel.
The highest BC emissions were said to be detected at 75% and 25% engine load, with the 0.50% sulphur fuel with 95% aromatic compounds showing the highest BC emissions at 25% load with 8 mg/Nm³, followed by 75% load with 7 mg/Nm³.
The study suggests that the results of the test indicate that it is necessary to include aromatic content in the ISO 8217 specification as this would enable a better assessment of bunker fuels in terms of their environmental performance in terms of BC emissions.