Maritime transportation company Exmar is set to add two more ammonia dual-fuel vessels to its fleet, bringing the total number of ships it operates capable of running on ammonia to four.

The company on Tuesday named Adinkerke and Aalter, its third and fourth oceangoing vessels capable of running on ammonia, Exmar announced in a LinkedIn post.

"ADINKERKE and AALTER will sail under the Belgian flag and will later be delivered in the capable hands of the captain and crew of EXMAR Ship Management," Exmar said in the post.

The two new vessels will join sister ships Antwerpen and Arlon in the company's fleet. Those earlier two ammonia-fuelled mid-sized gas carriers were delivered earlier this year as the world's first oceangoing vessels capable of running on ammonia. For Exmar, which has long specialized in the transport of liquefied gases, the move pairs its carrier expertise with a growing bet on ammonia as both a cargo and a fuel.

As Ship & Bunker reported last month, Antwerpen had completed its first commercial voyage using ammonia fuel, sailing from China to India.

Ammonia has attracted attention in the maritime sector as a potential zero-carbon bunker fuel, since it contains no carbon and can be produced from renewable energy. It is among the candidate fuels — alongside methanol, LNG, and hydrogen-derived options — being considered by shipping lines seeking to cut greenhouse gas emissions in line with targets set by the International Maritime Organization, which has called for net-zero emissions from international shipping around 2050. The fuel also presents handling challenges, as ammonia is toxic and requires careful containment and crew safety procedures, one reason seagoing deployments such as Exmar's remain closely watched across the industry.

The full report is available at Ship & Bunker.