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ISO statement on black carbon, VLSFO and ISO 8217 at IMO’s PPR meeting
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ISO statement on black carbon, VLSFO and ISO 8217 at IMO’s PPR meeting

The statement below was made by the represenative for the International Organization of Standardization (ISO),  Monique Vermeire, at the seventh session of IMO’s Sub-Committee on Pollution Prevention and Response (PPR 7) in February this year when discussing agenda item 8 – “Reduction of the impact on the Arctic of Black Carbon emissions from international shipping”. It has been reprouced here with her permission.

Mr. Chairman, distinguished delegates,

ISO thanks Germany and Finland for their submission. Having read the submission PPR 7/8  and the technical paper on “Combustion quality of low sulfur marine fuels after 2020 -will be better or worse ” referenced in PPR 7/8 and in particular paragraph 23 of PPR 7/8  recommending the introduction of a specification on aromatic content and H/C ratio in the ISO  8217 marine fuels specification standard. ISO would also like to draw attention to several pertinent facts and to have this statement recorded in the report of this meeting.

PPR 7/8 paragraph 6 states that the 0.50% S fuels tested in the black carbon measurement campaign have been selected as possible sample mixtures from refinery streams most likely to be used in 2020. This statement acknowledges the uncertainty as to whether these blends are realistic and indeed, the blends referenced to in the technical paper have been proven to be significantly different from fuels currently being supplied globally as max 0.50 % S fuel.

There are a number of reasons for this.

  • The technical paper referenced in PPR 7/8 was published in 2018, well before the max 0.50% VLSFOs were first introduced in the market.
  • Blend C referenced in the technical paper has an unusually high aromatic content and its choice at that time was not a realistic representation of the VLSFOs that refiners or traders were anticipating to supply.
  • The lack of a full characterisation of the fuels formulated, in this submission, including the methodology used for determining aromaticity, are lacking in order to make any comparison to current experiences.

In contrast:

  • Actual data available today on a few thousand samples from major testing services shows that in the period October 2019 up to 27 Jan 2020, VLSFOs have a lower average density of approximately 940 kg/m3 than HSFOs which have an approximate average density of 978 kg/m3. This points to VLSFOs being more paraffinic in nature than the Germany and Finland submission implied.

As suggested in the PPR 7/8 submission, the proposal to introduce aromatic content and H/C ratio specification into ISO 8217 can be considered by the ISO working group, however it should be understood that a number of routinely tested fuel characteristics such as density, pour point and micro carbon residue, are already good indicators for the nature of the fuels. This proposal will nevertheless be considered as to what other measures, if any, can be considered against what is already included.

Current fuel testing services data shows that:

  • Less than 5 % of the HSFOs have a pour point above 21 °C, whereas 20-25% of the VLSFOs have a pour point above 21°C. A higher pour point is indicative of a more paraffinic nature of the fuel
  • For the same period, VLSFOs have a lower average MCR (micro carbon residue) of approximately 5.8 m% than HSFOs which have an approximate average micro carbon residue of 12.8 m% also pointing to VLSFOs being more paraffinic in nature. The MCR gives an indication of the quantity and type of hydrocarbons in a fuel that have inferior combustion characteristics
  • The CCAI (Calculated Carbon Aromaticity Index) average is considerably lower for VLSFOs than HSFO, approximately 816 and 844 respectively. Low CCAI points to a more paraffinic fuel
  • Paraffinic fuels will have a higher Net Specific Energy value than more aromatic fuels, which is supported by the data drawn from the VLSFOs on the market today by as much as 2-3 %

PPR 7/8 submission shows increased black carbon emissions for fuels with high aromatic content when used in a medium speed test engine. High aromatic content may affect the combustibility of fuels, though low speed engines are less sensitive to the aromatic content than medium and high-speed engines.  This is well described in the CIMAC guide – Fuel quality -ignition and combustion and limits for CCAI (calculated carbon aromaticity index) are already included in ISO 8217. The type of engine and its settings, poor engine maintenance and certain operating conditions will contribute to the performance of the fuel and to the degree of black carbon emissions as well.

Since early analysis of VLSFOs supplied to vessels in Jan 2020 when compared with HSFO analysis data, illustrates the more paraffinic nature of VLSFOs than most of the HSFO, the ignition/combustion performance is expected to be improved and hence to result in lower BC emissions .

ISO did not take forward C/H ratio into ISO/PAS 23263:2019. In view of the revision of ISO 8217, ISO is already in the process of and will continue to monitor the VLSFO/HSFO properties and provide feedback on their performance.

ISO will also consider whether it is possible to add a further measure to what is already included to providing an approximate indication as to whether a fuel is rather more paraffinic or aromatic, based on the characteristics already included in the ISO 8217.

We should not overlook the fact that the industry is less than two months into 2020 and is still building experience with the new fuels.

Monique Vermeire of ISO making a statement at PPR 7

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