- Ammonia engine technology has matured, with 39 newbuilds on order by 2025, led by ammonia carriers.
- Ammonia requires nearly three times the storage space of MGO, and containment systems remain less efficient.
- High capital costs for ammonia-fueled ships vary by vessel type and fuel technology.
- Fuel availability and bunkering infrastructure have improved, but production, distribution, and safety remain key challenges.
Ammonia is gaining momentum as a possible zero-carbon fuel for shipping, offering a pathway to help the industry meet decarbonization targets. A new whitepaper from DNV, highlights the growing interest in ammonia following the International Maritime Organization’s (IMO) approval of the Net-Zero Framework in April 2025. While the fuel holds promise, the paper also points out safety concerns and barriers compared with conventional fuels, according to Safety4Sea.
Key Barriers to Ammonia Adoption in Shipping
The adoption of ammonia as a marine fuel has advanced since 2020, but several barriers remain. Technical maturity has improved significantly, with progress in engine technology and systems for both 4-stroke and 2-stroke engines. By August 2025, 39 ammonia-capable newbuilds were on order, led by first movers in the ammonia carrier segment, which accounts for 21 vessels, followed by 12 bulk carriers.
Volumetric energy density remains a challenge. Ammonia requires nearly three times the storage space of marine gas oil (MGO) for the same energy content. Its containment systems are less space-efficient than conventional integral tanks, and usable tank volume is further reduced by filling limitations and the need for additional structures such as cofferdams and connection spaces.
Capital expenditures (CAPEX) for ammonia-fueled ships are substantial, varying with fuel technology, vessel type, and size. Alternative fuel technologies make up a larger share of total costs for smaller vessels. As many newbuilds are still pending delivery in 2025, precise cost data remain limited and may not be widely disclosed.
The question of whether the fuel can be supplied is another critical factor. This includes energy costs, availability, and infrastructure. To support ammonia adoption, production and distribution of green and blue ammonia must meet the growing demand from ammonia-capable ships, while ensuring well-to-tank greenhouse gas (GHG) emissions align with stricter IMO and regulatory requirements.
Infrastructure development has progressed since 2020, although ammonia bunkering still poses safety and operational challenges. Demonstrations and preparations in multiple regions, along with the establishment of green shipping corridors, have lowered this barrier, paving the way for wider adoption.
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Source: DNV
