ISCO have called for two key response parameters to be made available on Bunker Delivery Notes, in order to facilitate rapid planning for oil spill recovery in a presentation given by Peter Taylor (Petronia) and Rob Cox (ISCO) at the 2025 ITAC meeting hosted by CEDRE in Brest, France this week.
The authors explained that the decision in October 2016 at MEPC 70 to set a limit of 0.50% sulphur content in low sulphur fuel oil from 1st January 2020 set in train several issues. The primary issue of concern until at least mid- 2019 was whether there would be sufficient supplies of <0.50% sulphur fuel available globally. Manufacturers rose to the challenge, and while there were occasional shortages at some ports, in general there was an adequate supply by the implementation date. However, it was already becoming clear, from testing by a consortium which included ISO, CONCAWE and Fuels Europe, that the way that these fuels potentially interacted with each other could in some cases lead to instability and the asphaltene precipitation. This led to the concern that incompatibility could occur when new bunkers were “loaded on top” of unused bunkers from a previous voyage.
Going into 2020 the focus was therefore on compatibility and the Joint Industry Guidance concentrated on this. It was recognized from the above testing that the increasing demand for very-low-sulphur fuel oil (VLSFO) was leading to an increase in the blending of lighter blend stocks to bring the sulphur content down to 0.50%, and many of these blend stocks were expected to be distillates. It was predicted that the new fuels would have a lower viscosity and be more paraffinic, i.e. prone to the formation of wax residues in cold temperatures, depending on the pour point. Quite what the variation in actual values would be was unknown as there was little operational experience.
For this reason, the Joint Industry Guidance (“The supply and use of 0.50%-sulphur marine fuel, available at: https://tinyurl.com/4vcurj9p) recommended a fuel supplier provide the following to the ship (page 27):
Typically, the specific information to be supplied should, at a minimum, include:
- confirmation of the ordering specification;
- viscosity;
- density;
- cold flow properties such as pour point and CFPP/CP as applicable to the grade of fuel;
- any other information that the supplier considers operationally useful for the ship to know; and
- a full CoQ related to the current fuel.
Although it was recognized that not all these parameters were required to be specified on the BDN and at the time, many shippers expressed a reluctance to pay for a full Certificate of Quality (CoQ) for each bunker stem.
There is a growing body of evidence on the variability of VLSFO composition. This has significant implications for oil spill preparedness. The fate and behaviour of spilled VLSFOs will vary widely, depending on their composition and ambient environmental conditions, including sea temperatures. Any general guidance on spill response options for VLSFOs would be necessarily broad and of limited use. Responders need specific information about a spilled oil for effective decision making.
In addition to informal discussions with ITOPF, on their experience with the MV WAKASHIO (Mauritius), AM GHENT (Gibraltar), EXPRESS PEARL (Sri Lanka), FELICITY ACE (Azores) and other incidents we have reviewed the following with a view to the properties of VLSFO as they inform clean up and recovery strategies:
- IMAROS(EU/Norway) study
- Interspill June 2022 presentation Session 6 (Chever, Le Masurier et al)
- ISO/PAS 23363 & ISO 8217 specifications
- SINTEF & CEDRE Studies
- CONCAWE/Fuels Europe/ISO studies
- MEPC 78/14/1 (Iceland and Norway)
The conclusion we have come to is that while nominal VLSFO specifications are useful for fuel suppliers and their customers, they provide limited clues to fate and behaviour if spilled to water. While a VLSFO will (hopefully) always meet the 0.50% sulphur limit, there can be wide variations in density, viscosity, cold-flow properties and stability, due to the wide variation in their component make-up. Spilled VLSFO may spread very quickly and flow freely or have a thicker consistency and even form waxy lumps. This depends on the oil properties such as pour point as well as the ambient sea temperature; physical properties will also change over time as the spilled oil loses volatile hydrocarbons.
Responders need rapid access to information concerning key properties of spilled fuel oils to mount a technologically appropriate response. It was to be hoped that the Safety Data Sheet would give this information, but our review has demonstrated that this is not the case. These parameters are often given as “typical” or provided as ranges which are not useful for response purposes given the high variability of these new fuels.
Following a discussion with ITOPF, we believe a possible solution may be to ask MEPC to add two parameters (viscosity and pour point) to the BDN parameters already specified under MARPOL Annex VI, to enable rapid and informed response. We note that MEPC 79 has been asked to adopt the inclusion of flashpoint to the BDN (MEPC 79/3/3), though this is not related to oil spill preparedness and response issues.
We do note, however, that in MEPC/78/14/1 (Iceland and Norway) paragraph 34 says:
“In the view of the co-sponsors, an upper pour point limit should be included in the definition of HFO in regulation 43.1.2 of MARPOL Annex I. The limit should be set to 0⁰C and would lead to an indirect requirement for the fuel oil composition in relation to wax content and other components in the fuel oil influencing the pour point.”
While accepting that this only pertains to the Arctic, the consequence of the above is surely the same as with maximum sulphur content which has to be recorded on the BDN; if the pour point is subject to a mandated limit under Marpol Annex VI then surely it also should be recorded on the BDN.
In closing we note that there is a caveat in this approach – given that ships usually load bunkers “on top” of each other, and do not have the tankage to segregate different bunker stems, it cannot necessarily be guaranteed that the spilled bunkers are from a single source, however having the Pour Point listed on the BDN would provide information as to the range of possibilities, thereby facilitating informed decision making.
