The International Maritime Organization (IMO) has introduced interim guidance on the carriage of biofuel blends mixed with MARPOL Annex I cargoes by conventional bunker ships.
The guidance applies to bunker ships classified as oil tankers under MARPOL Annex I Regulation 1.5, which must hold certification to transport and deliver marine fuel oil.
Under the new rules, crews are required to discharge all tank residues or washings ashore, unless the vessel’s oil discharge monitoring equipment is approved for the specific biofuel blend carried.
If these requirements are met, ships can retain their existing International Oil Pollution Prevention Certificate without the need for modification.
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For bunker ships carrying biofuel blends above 30 per cent, compliance with MARPOL Annex II and Chapter 17 of the International Bulk Chemical (IBC) Code is mandatory.
Meanwhile, on vessels other than bunker ships, biofuel blends containing 25 per cent or less biofuel remain regulated under MARPOL Annex I. Blends exceeding 25 per cent fall under MARPOL Annex II and must meet IBC Code provisions.
The IMO has also outlined the approved biofuels under these regulations, detailed in MEPC.2/Circular, Annex 11.
This guidance represents a key step as the maritime sector transitions toward greater use of alternative fuels while maintaining environmental safety and regulatory compliance.
