The International Maritime Organization’s Sub-Committee on Pollution Prevention and Response has agreed amendments to enable the certification of marine engines operating on non-carbon fuels including ammonia and hydrogen, according to classification society DNV.

The amendments to the NOx Technical Code introduce hydrogen and oxygen balance methodologies to complement the existing carbon balance approach for emissions certification. The changes are expected to be approved at the Marine Environment Protection Committee’s 84th session in April 2026, with adoption planned for MEPC 85 in November 2026.

DNV reported that the 13th session of PPR, held in London from February 9–13, also commenced discussions on a legally binding framework for biofouling control to minimize the transfer of invasive aquatic species. The committee agreed that a new convention would be the most suitable approach and recommended this for consideration at MEPC 86 in 2027, with the aim of finalizing a draft legal framework by 2029.

The committee agreed to amend MARPOL Annex VI to require crude oil tankers to be fitted with pressure/vacuum valves having a minimum opening pressure of 0.20 bar as a measure to reduce volatile organic compound emissions. This requirement will apply only to crude oil tankers constructed on or after the entry-into-force date of the amendments.

PPR 13 also agreed amendments to MARPOL Annex I introducing a new Regulation 12B covering oily bilge water service tanks for controlled dewatering, including removal of water by forced evaporation. The regulation will apply to ships above 400 gross tonnage fitted with an integrated bilge water treatment system installed on or after the entry-into-force date.

The committee commenced a review of NOx emission requirements under MARPOL Annex VI and the NOx Technical Code, according to DNV. The review will address elevated NOx emissions at low engine loads, though divergent views exist on whether this should be achieved through modifications to test cycles and weighting factors or through alternative regulatory approaches.

PPR 13 examined options to enhance on-board NOx compliance verification, including the potential use of electronic diagnostic functionalities, though no preferred solution was identified. Intersessional work will continue across all areas to develop regulatory proposals for consideration at PPR 14 in 2027.

Regarding exhaust gas cleaning systems, the committee concluded that for any future Particularly Sensitive Sea Area designations, proposing member states should first undertake a risk assessment and subsequently determine whether discharge restrictions are reasonable based on the assessment’s findings.

The committee also progressed the revision of MARPOL Annex IV on sewage treatment, developing draft amendments related to the Sewage Record Book, Sewage Management Plan and associated guidance. A correspondence group was established to continue this work for PPR 14 in 2027.

PPR 13 discussed the development of a polar fuel concept to reduce black carbon emissions in the Arctic. A polar fuel standard was identified as a possible initial measure, but the committee emphasized that fuel quality alone cannot mitigate black carbon formation. Member states and organizations were invited to submit refined proposals to PPR 14, taking into account the need for consistency with other MARPOL Annex VI requirements.

The committee agreed to assign special requirement 16.2.7 to twelve additional high-viscosity or solidifying products under the International Bulk Chemical Code and approved two new tank-cleaning additives. Concerns were highlighted over adequate port reception facilities as the amount of affected cargo increases.

After considering different pathways for making mandatory measures to prevent environmental pollution from plastic pellets transported at sea, the preferred option was to develop a new mandatory code for plastic pellets under MARPOL Annex III, SOLAS or both. PPR 13 recommended MEPC 84 make a policy decision on the preferred mandatory instrument.

DNV noted that as PPR is a sub-committee, all decisions concerning rules, regulations and dates are subject to further consideration and approval by MEPC.