Study: New Blends of Marine Fuels Have Higher BC Emissions than HFO

New blends of marine fuels with 0.50% sulphur content can contain a large percentage of aromatic compounds, which have a direct impact on black carbon emissions, a recently conducted black carbon measurement campaign finds.

The results of the study were cited in a submission made by Finland and Germany to the IMO’s Pollution Prevention and Response (PPR) sub-committee for revision at its session scheduled for February, seeking adequate action be taken.

The measurement campaign was conducted by a German non-profit-making research institute WTZ Roßlau and was assisted by MAN ES, DNV GL and Marena Ltd. The project was funded by the German Environment Agency.

The study was carried out on the recommendation from MEPC delegates to further develop BC measurement methods in the light of the sulphur cap implementation and reducing the impact of black carbon emissions from shipping on the Arctic.

Under the new regulation, which entered into force on January 1, 2020, the limit for sulphur in fuel oil used on board ships operating outside designated emission control areas is reduced to 0.5% from 3.5%. This is expected to significantly reduce the amount of sulphur oxides emanating from ships.

The international shipping community has had to switch to low sulphur fuel, start using scrubbers or turn to LNG or other alternative fuels like LPG, methanol, biofuels or even ammonia.

However, the relatively new marine fuel blends are yet to be put to the test when it comes to their friendliness to the environment.

Shipowners have voiced their fears that the new fuel blends might pose a risk of contamination to a ship’s systems, causing breakdowns and safety risks to the crew.

The latest study casts a darker shadow on the new blends, increasing the pressure on bunker suppliers and refineries to up their game.

As indicated in the submission, the emphasis of the measurement campaign was to analyse the BC emissions of future hybrid fuels with 0.50% sulphur content from different sources and different production processes, in comparison to two conventional fuels, heavy fuel oil and Distillate Marine Fuel (DMA), and a possible future synthetic Gas to Liquid (GtL) fuel, at varying engine ratings on a test bed.

All tests were performed with the same lube oil.

The tested 0.50% sulphur fuels have been ordered as possible sample mixtures from refinery-streams most likely to be used in 2020. As informed, high aromatic content in future low sulphur marine fuels after 2020 is expected.

The research found that new hybrid fuels with 0.50% sulphur content used in the study contained a high proportion of aromatic compounds in a range of 70% to 95%, which resulted in increased BC emissions in a range of 10% to 85% compared to HFO and in a range of 67% to 145% (a factor of 2.45) compared to DMA.

“The results of this measurement campaign imply that it is necessary to implement aromatic content, or H/C ratio, in the specification of marine fuels of the ISO 8217 petroleum standard. This would enable a better qualification of marine fuels with respect to their environmental performance in terms of BC emissions and benefit their characterization for ignition and combustion quality.

“It is suggested that the International Organization for Standardization review ISO 8217 to include specifications taking into account these results,” the study concludes.