Maritime transport moves goods, people and resources by sea, river and through ports. It includes international shipping, coastal freight, bulk export vessels, ferries, workboats, cruise vessels, fishing vessels and port operations. Low carbon liquid fuels can play a role where vessels need long range, high power, fast refuelling and reliable operation away from shore.
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99%of Australia’s international trade by volume
Australian ports move around 99% of Australia’s international trade by volume, about 1.6 billion tonnes of imports and exports a year, worth around $650 billion.
31,000ship visits a year
Australian ports receive around 31,000 international trading vessel visits each year, alongside 1.25 million cruise passengers.
Around 3%of global greenhouse gas emissions
International shipping accounts for around 3% of global greenhouse gas emissions.
Net zeroby or around 2050
The International Maritime Organization (IMO) 2023 strategy targets net zero greenhouse gas emissions from international shipping by or around 2050, with indicative checkpoints for 2030 and 2040.
How maritime is reducing emissions
Maritime decarbonisation involves a combination of measures rather than a single solution. The mix differs by vessel type, route and cargo.
More efficient vessel design and engines
Newer hull designs, propulsion systems and engine improvements can reduce fuel use per tonne-kilometre and lower emissions over time.
Operational improvements
Slow steaming, weather routing, just-in-time arrivals at ports, hull cleaning and trim optimisation can reduce fuel burn on existing vessels.
Increased use of low carbon liquid fuels
Drop-in fuels such as renewable diesel can be supplied through some existing bunkering networks once they meet the relevant marine fuel specification. Other low carbon fuels need vessels and infrastructure designed for them.
Wind-assist, shore power and emerging propulsion
Wind-assisted propulsion, shore power at berth, batteries on shorter routes and hydrogen fuel cells are being trialled but are not yet mainstream replacements for liquid fuels in deep-sea shipping.
Low carbon liquid fuels for maritime
Several low carbon liquid fuels are being explored for marine use. They differ in feedstocks, maturity, and how they interact with existing engines and bunkering infrastructure. Low carbon maritime fuel use is at an early stage globally and maritime fleet is slow to change because ships have long operating lives, and new fuel choices affect vessel design and port infrastructure.
| Fuel | Application |
|---|---|
| Renewable diesel | Suitable for some marine diesel applications where it meets the relevant fuel specification and engine-maker requirements. A drop-in fuel where compatible. |
| Biodiesel | Used as a blend within marine fuel specifications. Compatibility depends on the vessel, fuel grade, storage conditions, fuel testing and engine-maker guidance. |
| Renewable methanol | Used in methanol-compatible marine engines and fuel systems. |
| Renewable liquefied natural gas (LNG) | Used in LNG-compatible marine engines and fuel systems, requiring cryogenic storage and LNG bunkering infrastructure. A drop-in fuel where compatible. |
| Renewable ammonia | A specialist marine fuel pathway, requiring dedicated vessel designs, appropriate onboard storage systems, and new port-side bunkering infrastructure. |
Bunkering and port logistics
Bunkering means supplying fuel to a vessel, through fixed port infrastructure, road tankers, barges or ship-to-ship transfer. For maritime, the supply chain is more than the fuel itself: it also covers moving the fuel to the right port, storing it in suitable tanks, testing and documenting fuel quality, transferring it to vessels, using compatible on-board equipment, training staff, and meeting port and environmental requirements.
Drop-in diesel-type fuels can use much of the existing bunkering network where they meet specifications. Renewable methanol and renewable ammonia generally need new or modified storage, transfer equipment and procedures.
where the fuel is made
moving fuel to port
in port tanks
fuel quality checks
transfer to vessel
in vessel engines
Maritime fuels today
Low carbon liquid fuel use in maritime is at an early stage globally. A number of demonstration vessels are now operating on renewable diesel, biodiesel blends, renewable methanol or renewable ammonia, and a growing number of standards and policy frameworks are in place to guide expanded use.
More than 2,000 alternative-fuelled vessels
In operation or on order globally, including ships using liquefied natural gas, methanol, ammonia, biofuels and battery-hybrid systems.
Bunkering at major international ports
Renewable methanol bunkering is operating or being established at a small number of major international ports including Rotterdam, Antwerp, Singapore, Houston and Ulsan.
Multiple low carbon marine fuel pathways
Renewable diesel, biodiesel and fatty acid methyl ester blends, renewable methanol, renewable ammonia and synthetic diesel-type fuels are at varying stages of demonstration and early commercial deployment for marine use.
Australia
CSIRO · 2025
Bioenergy Australia · 2025
ARENA · 2021
International
IRENA · 2019
IEA · 2025
IEA Bioenergy Task 39 · 2024
Policy, regulation and technical guidance
The sections below cover the standards, policy, certification criteria and mandates shaping low carbon liquid fuel use across the maritime sector, grouped by the role they play.
Australia’s maritime safety regulator. Represents Australia at the International Maritime Organization (IMO) and oversees vessel compliance for Australian and foreign ships in Australian waters, including air pollution and fuel quality requirements.
Publishes the international marine fuel specifications used by ships, ports and bunkering operations. ISO 8217:2024 covers conventional marine fuels with new provisions for fatty acid methyl ester content; ISO 6583:2024 covers methanol as a marine fuel.
Sets international shipping safety and pollution prevention standards through the International Convention for the Prevention of Pollution from Ships (MARPOL) and associated codes, including the International Code of Safety for Ships Using Gases or Other Low-flashpoint Fuels (the IGF Code), which applies to gas and other low-flashpoint fuels. Methanol and ammonia fuelled vessels are covered by separate IMO interim guidelines rather than by the Code itself.
Provides funding and support for low carbon liquid fuel studies, demonstrations and infrastructure work, including renewable diesel and renewable methanol projects with maritime applications.
Australia’s Guarantee of Origin scheme, which is administered by the Clean Energy Regulator, provides a transparent, publicly accessible record of the emissions associated with the production of key commodities. The scheme is being expanded to cover low carbon liquid fuels, including fuels for maritime use.
Sets the well-to-wake life-cycle greenhouse gas methodology for marine fuels through the 2024 Life Cycle Assessment Guidelines (Resolution MEPC.391(81)), which underpin the IMO Net-Zero Framework and provide a common basis for assessing emissions across the fuel life cycle.
Independent global certification scheme covering sustainable biomass, bio-based materials, renewable fuels and circular economy products. ISCC is widely used across European Union renewable fuel pathways including marine biofuels supplied under FuelEU Maritime.
The 2023 IMO Strategy on Reduction of GHG Emissions from Ships sets the global ambition of net-zero international shipping emissions by or around 2050, with indicative checkpoints to cut total annual emissions by at least 20% (striving for 30%) by 2030 and at least 70% (striving for 80%) by 2040, both compared with 2008, and a target for at least 5% (striving for 10%) of international shipping energy to come from zero or near-zero emission fuels and technologies by 2030.
The IMO Net-Zero Framework was approved at MEPC 83 in April 2025 as a new Chapter 5 of MARPOL Annex VI. It would introduce a global fuel standard with annual greenhouse gas fuel intensity reduction targets and a credit trading scheme for vessels over 5,000 gross tonnage. Adoption was deferred at the extraordinary MEPC session in October 2025; the session is scheduled to reconvene in late 2026, pushing earliest entry into force to 2028.
Administers FuelEU Maritime, the European Union regulation requiring rising greenhouse gas intensity reductions for ships calling at European Union ports. Begins with a 2% reduction in 2025 and rising to 80% by 2050 in well-to-wake greenhouse gas intensity.
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