International shipping's path toward decarbonization remains under negotiation. Support for an International Maritime Organization-led solution appears to be holding. However, important questions about the pace and design of the transition remain unresolved.
The IMO's Intersessional Working Group on Reduction of Greenhouse Gas Emissions from Ships met September 1–4 to advance discussions surrounding the Net-Zero Framework. Further talks are scheduled for November, followed by the Marine Environment Protection Committee meeting from November 30 to December 3 and an expected Extraordinary Session on December 4.
One possible outcome is a framework that initially imposes less stringent greenhouse gas reduction requirements but later accelerates them. Such a compromise could provide the industry with more time to prepare. But it could also prolong investment uncertainty and increase the importance of bio-bunker fuels as an immediately available decarbonization option.
The Net-Zero Framework is intended to translate the ambitions of the 2023 IMO GHG Strategy into enforceable requirements. Yet countries continue to disagree over how quickly those requirements should take effect and how the framework's economic elements should operate.
One central issue is the proposed greenhouse gas fuel intensity, or GFI, trajectory. The GFI mechanism would progressively reduce the allowable emissions intensity of energy used aboard ships. This would encourage operators to transition toward lower-carbon fuels and technologies.
According to a Prima CarbonZero market report, several delegations have proposed easing the framework's initial strictness during the early years of implementation. The result could be a more gradual reduction around 2030, followed by a steeper trajectory toward 2040.
This approach may make the framework more manageable at the outset. The concession could serve a particularly important purpose while the availability, scalability and affordability of alternative marine fuels remain uncertain.
But reducing near-term ambition would not necessarily remove the industry's longer-term decarbonization obligation. Instead, it could shift more of the required change into a shorter period.
As a recent analyst commentary in Prima CarbonZero notes, shipowners, fuel producers, and infrastructure developers must make investment decisions long before the final shape of future fuel demand is known. Accordingly, uncertainty surrounding the IMO framework affects more than regulatory compliance. It influences which vessels, production facilities, and supply chains receive capital.
The one-year adjournment of the Net-Zero Framework vote in October 2025 reportedly contributed to a slowdown in some investments in low-carbon fuels and propulsion technologies. Continuing disagreements could reinforce that caution, particularly for projects dependent on a clear long-term compliance signal.
A less ambitious initial GFI trajectory could have a similar effect. If near-term compliance pressure is reduced, some market participants may have less incentive to commit immediately to fuels and technologies that require new production capacity, vessel modifications, or specialized infrastructure.
However, delaying those investments could leave the sector facing a more difficult transition as requirements tighten more rapidly.
In this environment, available bio-bunker fuels may become increasingly important.
Compared with several emerging marine fuel pathways, certain biofuel blends can be introduced with fewer changes to existing vessels and bunkering infrastructure. This can make them a more accessible option for operators seeking to reduce emissions while preserving flexibility around longer-term fleet and fuel decisions.
A softer initial compliance trajectory would not automatically translate into stronger bio-bunker demand. Actual uptake will also depend on feedstock availability, fuel pricing, sustainability requirements, lifecycle emissions, and competition from road transport, aviation and other sectors.
Nevertheless, prolonged uncertainty around the Net-Zero Framework could extend the period in which drop-in and blended biofuels serve as practical transitional tools. Rather than committing immediately to a single long-term propulsion pathway, some operators may use bio-bunker fuels to achieve incremental emissions reductions. But they must still monitor how regulation, technology, and fuel supply develop.
Although important details remain contested, the underlying GFI concept appears to retain broad support. The transfer and pooling of Surplus Units, the mechanisms that would give operators greater flexibility in meeting requirements, also appear less controversial.
The larger disagreements concern how the GFI system should be structured and how demanding its trajectory should be. Discussions include whether the IMO should retain the proposed two-tier approach or adopt a single-tier model similar to FuelEU Maritime.
Behind that technical debate is a more fundamental policy question:
Should regulation be set aggressively enough to stimulate investment and create demand for new fuels, or should its ambition reflect the fuels currently available at scalable and affordable levels?
The meetings scheduled for November and December will be critical in determining whether countries can reach sufficient agreement on the Net-Zero Framework's final design.
For biofuel producers, traders, bunker suppliers and shipowners, the outcome will help shape both the pace of marine decarbonization and the competitive position of different fuels. A softer beginning could extend the opportunity for available bio-bunker solutions. But it may also set the stage for a sharper compliance challenge later.
The direction of travel remains decarbonization. The unresolved question is how quickly the industry will be required to move and which fuels will be best positioned to bridge the gap.
As the IMO negotiations continue, marine fuel market participants will need to follow more than the final policy outcome. Shifts in regulation, regional demand, biofuel and feedstock pricing, and supply availability will all influence the role bio-bunker fuels can realistically play.
Bio-Bunkering at a Glance: Marine Biofuels Update provides a monthly overview of the developments shaping this evolving market. Each edition brings together policy and regulatory updates, regional market activity, fuel and feedstock price trends, and expert analysis to help you understand what changing conditions could mean for marine biofuel demand and strategy.