The NZF is the IMO’s regulatory response to the 2023 IMO GHG strategy. If adopted, this new legally binding framework will include requirements on GHG fuel intensity ‘which will be the first of its kind to cover a global industry sector’, claims DNV. The new regulations were approved by the Marine Environment Protection Committee 83 in April 2025 and are expected to take effect from 2028, applying to ships over 5,000 Gt engaged in international trade.

Environmental performance will be measured as ‘well-to-wake’ GHG emissions per energy unit used. However, shipping owners and operators are concerned that the NZF represents a new regulatory era for the sector in which ships will be required to adopt fuels that are typically three to four times more expensive than conventional fossil fuels (heavy diesel).

DNV suggests that given the long lifespan of ships, ‘shipowners should prepare now for the new net zero GHG emission regulations to ensure cost-effective compliance’.

Europe is already leading the way. FuelEU Maritime Regulations were adopted in January 2025 setting the annual average GHG intensity of ships trading within the EU (in gCO₂e/MJ), calculated from a well-to-wake perspective. Starting at 2% GHG intensity reduction in 2025 and aiming to reach 80% reduction by 2050.

The scale of the challenge
Aiming for a similar level of GHG reduction globally in the maritime sector is no mean feat. Accelleron launched its first maritime decarbonisation report at London International Shipping Week in September, with a call for the industry to join the global hydrogen economy by working with other sectors to pool demand for carbon-neutral fuels.

The report, titled Deadlock: what’s stopping shipping’s carbon neutral fuel transition?, suggests that shipping will need to address several hurdles in the switch to green hydrogen-based fuels (like methanol and ammonia) which are scarce and expensive today.

Using comparative data modelling and insights from dozens of senior executives, the report claims that ‘shipping alone cannot solve this problem’. It argues for a cross-sector approach to kickstart production of affordable carbon-neutral fuels, working with other ‘hard-to-abate’ sectors such as the steel, chemicals, cement and power-generation industries.

Christoph Rofka, President, Medium- and Low-Speed, Accelleron, points out that energy saving technologies applied to the largest 50,000 ships in the global fleet could deliver emissions cuts beyond the IMO’s 2030 reduction target of 30%.

However, he insists that ‘efficiency measures are no longer sufficient’. Less than 40% of vessels worldwide have implemented the energy-saving measures. And even if applied across the full global fleet, efficiency can only stretch the use of current fuels and slow the rise in emissions. ‘True decarbonisation requires the use of new, carbon-neutral fuels. And we could see an exponential uptake of dual-fuel capable vessels in the order book,’ says Rofka.

By 2050, the shipping sector is estimated to need 100–150mn t/y of green hydrogen, using 4,900–5,900 GW of renewable electricity to produce e-methanol and e-ammonia. What’s more, this will be competing with the green hydrogen demands of other hard-to-abate sectors like aviation, steel, power, cement and chemicals. And building the global green hydrogen supply chain is predicted to cost about $9tn.

Maritime GHG emissions reached 974mn tonnes in 2024, the highest on record. However, on the positive side, nearly 50% of all ship tonnage ordered in 2024 was dual-fuel capable.

‘Improving maritime efficiency should “go viral” as the most cost-effective decarbonisation lever today.’ – Christoph Rofka, President, Medium- and Low-Speed, Acceleron

Five major hurdles
According to the report, the shipping sector faces five major hurdles when comparing potential carbon-neutral pathways.

Rofka explains that to supply shipping’s 2050 needs, ‘any single carbon-neutral fuel would have to scale to levels that dwarf current global production’. Full decarbonisation would require 803mn t/y of methanol, 859mn t/y of ammonia or 333mn t/y of LNG. And shipping only accounts for less than 1% of biofuels’ use today. Although dual-fuel ships dominate current orderbooks, there is still a significant lack of scalable carbon-neutral fuels worldwide.

Five interlinked issues are mentioned that actually extend beyond shipping into every hard-to-abate sector.

Fuel pathway uncertainty 
A proliferation of fuel pathways are being trialled, including LNG, biofuels and e-fuels, but not at scale. Shipping, which has traditionally relied on heavy diesel, is now competing for premium fuels. The economy of scale required for competitive green hydrogen production will require long-term offtake contracts, which shipping cannot commit to until a reliable, affordable supply is available. ‘Scale matters to get the cost down,’ Rofka remarks.

Fuel geography will be critical
Carbon neutral fuels are not just costly but are geographically constrained, with vast green hydrogen hubs required. For example, the Western Green Energy Hub in Western Australia will be 30 times the size of Singapore, and is forecast to use 70 GW of renewables to produce 28mn t/y of ammonia.

Kofka makes the point that ‘though such scale can drive costs down, it also concentrates supply in just a handful of locations’. Whereas many shipping companies rely on accessing fuel all over the globe. ‘Fuel availability constraints will fracture shipping’s traditional operational flexibility and reshape the sector’s business model,’ he says.

The green finance paradox
Green finance capital remains inaccessible to the scale of investment required, due to fundamental mismatches between shipping’s commercial structures and environmental, social and governance (ESG) investor requirements. Only a fraction of ESG-related capital is targeted at shipping, due to its fragmented ownership base, long vessel lifespans, hazy ESG reporting and uncertain regulation. ‘Without aggregated, cross-sector commitments to boost returns and share risk, the green finance gap will persist,’ asserts Rofka.

Misalignment between ambitious regulatory frameworks and the reality of implementation
Despite shipping having a good record in terms of global regulation, ‘the IMO is almost always a bit late’, remarks Rofka. Alhough the NZF was adopted in April 2025, incentives will not flow until 2028. This may be too late for projects that must reach final investment decision now to deliver fuels by the 2030s. ‘Without a solid regulatory framework, decarbonisation will just not happen, as long-term certainty is essential,’ says Rofka.

Infrastructure bottlenecks at ports 
Even if the fuels are produced, they cannot reach ships without sufficient port infrastructure, connecting shipping to pipelines, water and storage networks. Considering the scale of the problem, each tonne of hydrogen requires 50–55 MWh of electricity and 20–30 litres of water. So, competition for electrons and water will be acute. Permitting adds further delays. And there will be both a challenge and opportunity maintaining legacy bunkering while phasing in carbon neutral fuels.

Furthermore, these issues are interlinked. ‘Shipping’s 300mn tonnes of annual fuel demand looks vast. But even when it isn’t spread out across multiple fuel pathways, it is too small to trigger green hydrogen development,’ argues Rofka. Aggregating cross-sector demand will be vital – given that ports are the natural focus of maritime, industrial and energy systems.

Delving a little deeper: ‘The IMO is calling for a minimum of 5% net zero fuels by 2030. But as it stands, only 90% of this 5% can be achieved, and less than half of this is scalable,’ Rofka explains. ‘So, it’s a question of making multiple choices between biofuels, LNG, methanol, ammonia and others. These are all competing for investment, and big ship owners are creating individual agreements, which are not scalable. The fuel choices are fragmented, silo thinking, which prevents it from scaling.’

Breaking the deadlock
The report highlights several key findings.

First, ‘improving maritime efficiency should “go viral” as the most cost-effective decarbonisation lever today’, says Rofka. Technical and operational efficiency measures could cut GHG emissions over 30% by 2030. They also amplify the impact of every scarce tonne of carbon-neutral fuel used.

Notably, the ships are ready to handle dual-fuel, but the fuels are missing. Dual-fuel vessels dominate the order books, but planned e-fuels cover only 4–8% of the IMO’s 2030 target.

Green hydrogen is indispensable, but shipping, in concert with other hard-to-abate sectors, requires a total of 500mn t/y of green hydrogen by 2050. Here again Rofka insists: ‘Cross-sector alliances are the only way to trigger this level of production at scale.’

Furthermore, biofuels are only a stopgap, capable of supplying only a tiny proportion of maritime demand.

On the financial front, it is an imperative that green finance gaps must be closed. Without new structures to de-risk mega-projects, trillions in capital will remain idle.

As a rule of thumb, ‘global goals need local action’, says Rofka. ‘The IMO represents 85% of international shipping. That’s a strength as many other industries are not regulated at international level. Marine has the advantage to be global, but it’s a complex environment. National energy policy must create incentives on supply and demand sides to stimulate hydrogen production, and support IMO’s net zero goals,’ he says.

Finally, ports can provide the platform for shipping to play a more significant role in the energy transition, but who will lead?

Rofka concludes: ‘The money is available to finance the transition to carbon-neutral fuels. The shipping industry has only attracted a small portion of global ESG assets so far. The reason is clear – shipping does not provide enough evidence, enough commitment [to ESG], forward looking and also in volume… If the maritime sector takes action, then it will become a lot more attractive for companies and majors to invest in energy.’

• Further reading: ‘Maritime decarbonisation: ports and green shipping corridors’. The Port of Huelva is assisting in the development of both alternative maritime fuels and green shipping corridors, thanks to its geographical position in the southern part of Spain. Director of the Port Authority of Huelva, Ignacio Álvarez-Ossorio Ramos, explains.
• Find more about the UK government’s updated plans to decarbonise the shipping sector, including new emissions targets for 2030 and 2040 as well as fresh measures to support alternative fuels and electrification.