Pollution Prevention and Response (PPR) sub-committee meetings are always an important and informative prelude to the main MEPC meetings that take place a few months later.
While there was no doubt some discussion and speculation among delegates to the January 2025 PPR 12 meeting about how far the election of Donald Trump for a second term as US President might impact forthcoming IMO measures around GHG and fossil fuels, the agenda for the meeting had been set sufficiently prior to not be affected.
Fuels did come up but primarily in connection with reduction of Black Carbon in the Arctic. Much work has been done at previous sessions and at PPR 12 was focussed on various characteristics of fuels that should be included in guidelines. It was agreed further work was needed and discussions took place over whether to include biofuels, biofuel blends and gaseous fuels in the “polar fuels” concept, as well as alternative fuels such as LNG, hydrogen, methanol and ammonia. Further submissions were invited for PPR 13 to allow discussions to progress.
SOx, NOx sewage treatment and bilge systems debated
Exhaust gases or at least treatment methods were major elements of the meeting with discharge waters from exhaust gas cleaning systems (SOx scrubbers) and amendments to the NOx Code with regard to SCR systems both featuring.
Scrubber discharge waters have been an emotive subject for many years now at this meeting too, the views expressed varied considerably. Many delegates supported restrictions on discharges and sought amendments to MARPOL Annex VI, others suggested a need for more technical improvements to scrubbers and others still proposed that coastal states be allowed to introduce national regulations. The last suggestion has in fact already been implemented by many states and port authorities with the ironic result that some states allow ships under their flag to install scrubbers but do permit their use on any ships in their own territorial waters.
The meeting held the matter over and invited further proposals to PPR 13 while also drawing up proposals for a re-established GESAMP task force on EGCS that would develop a standard methodology for calculating emission factors and consider additional emission factors for relevant chemical substances not currently listed in the 2022 Guidelines for risk assessment of the discharge water from EGCS (MEPC.1/Circ.899). Both measures will need to be approved at MEPC 83 in April this year.
On the Nox Code and the 2017 SCR Guidelines, the meeting debated the need for additional guidance on certifying systems managing multiple engines simultaneously. The Sub-Committee completed the draft 2025 SCR Guidelines and agreed that these should apply only to new installations and that existing Technical Files should not be revised. The 2025 Guidelines will be submitted to MEPC 83 for adoption.
Sewage treatment plants were another agenda item with discussions around whether the draft revision of MARPOL Annex IV should be retrospectively applied to existing sewage treatment plants. Due to a lack of consensus, it was decided to revisit this issue at a later stage, closer to the completion of the amendments. MEPC was requested to extend the target completion year for the draft amendments to 2027.
Back at MEPC 78 it was agreed that in principle that forced evaporation by integrated bilge water treatment system (IBTS) could be applied to the disposal of oily bilge water. The matter has still to be decided and PPR 12 considered two proposals to amend MARPOL Annex I. Because of lack of time this was deferred to PPR 13.
In water cleaning under the microscope
An issue that has been growing in importance in recent years is that of biofouling. The impact on vessel efficiency of a badly fouled hull can significantly increase fuel consumption and therefore GHG emissions and there is also the risk of carrying invasive species. None of this is anything new but it is now near the top of the IMO environmental agenda. In 2023, the IMO issued resolution MEPC.378(80) titled 2023 Guidelines for control and management of ships’ biofouling to minimize the transfer of invasive aquatic species with the expectation that there may soon be some mandatory regulations around the subject.
There has been some significant innovation in development of robotic hull cleaning devices some of which are intended to keep a ship’s hull in a condition where no fouling or just the initial bacterial slime is present. However, holding back take up of cleaning system sales and cleaning services has been the lack of any concrete standards. There is an ISO standard being developed but this could conflict with any potential new IMO rules.
Of particular interest is whether rules should allow for systems that do not capture any cleaning debris. Some makers of systems designed to keep hulls in a permanently clean state argue that capture is not necessary while some observers remain to be convinced that the risk of species transfer or the introduction into the environment of coatings components is negligible with such systems.
PPR 12 finalised its guidance on matters around in water cleaning and whilst it is relatively comprehensive it does not have universal support and there is still work to be done. The work needed concerns methodologies for compatibility between cleaning system and coating, for performance standards and inspections of in water cleaning results. The guidance may be approved by MEPC 83 but more alignment with the growing number of local regulations that are appearing may be necessary.
Also under discussion
There were various proposals to address the issue of the pollution risk of plastic pellets in containers but rather than choose any of these it was decided to consider mandatory measures as a new action in the 2025 Action Plan to address marine plastic litter from ships which should be completed by 2030. Another new action for a ship-specific management plan for fishing gear was also agreed.
PPR 12 revised the 2023 Guidelines for the Development of the Inventory of Hazardous Materials, clarifying the relevant threshold of cybutryne when samples are taken directly from the hull or from wet paint containers.
With biofuels increasingly being used around the globe including as fuel for ships, the meeting finalised draft interim guidance for the carriage of biofuel blends and MARPOL Annex I cargoes by conventional bunker ships engaged in transporting and delivering fuel oil to other ships. This guidance allows conventional bunker ships to transport biofuel blends containing no more than 30% biofuel by volume, provided that all residues or tank washings are discharged ashore.
Several recent pollution incidents arising from tank cleaning by vessels carrying Fatty Acid Methyl Ester (FAME) cargoes had resulted in a proposal to add operational requirement 16.2.7 to the IBC Code entry for FAME. The ESPH Technical Group, reporting back to PPR 13 in 2026, was tasked with further consideration of this proposal.
An issue brought up at MEPC 81, seeking clarification on the carriage of cargo oil in the slop tank(s) of an oil tanker, was deferred to PPR 13 due to the lack of comments.