The world's first operational ammonia bunker vessel has entered service, Swedish naval architecture firm FKAB reports, marking the first time a vessel has received an ammonia bunkering class certificate and become operationally ready for ship-to-ship liquid ammonia fuel transfer.

The vessel, Shenghang Yongle, was originally designed as a flexible liquefied gas carrier before being converted into a dual-purpose vessel capable of both transporting liquid ammonia and delivering it as fuel through ship-to-ship bunkering. The conversion was led by Jiangsu Andefu Energy Development, with FKAB and cargo handling supplier Gloryholder providing the technical drawing documentation, and China Classification Society overseeing the certification process.

The 5,500-cbm semi-refrigerated and semi-pressurised liquefied gas carrier was designed by FKAB, built by China Merchants Shipbuilding Industry Dingheng shipyard, and is managed by Shenghang Shipping Co., Ltd. Designed for unrestricted navigation, the vessel is capable of carrying several liquefied gas cargoes including ammonia, LPG and vinyl chloride monomer. Its cargo tanks have a minimum design temperature of −48°C, and the vessel is equipped with two low-temperature reliquefaction systems.

While several ammonia bunker vessel projects have reached design, feasibility or construction stages in recent years, the Shenghang Yongle is said to be the first to have progressed into operational readiness.

The conversion work included modifications to the bunkering system, development of operating procedures, risk assessments, and the establishment of safety and emergency-response arrangements. According to FKAB, particular attention was given to the challenges associated with ammonia, including its toxicity, material compatibility, low-temperature operation, leak detection and risk control during bunkering operations.

Ammonia is regarded by parts of the shipping industry as one of the most promising potential zero-carbon marine fuels when produced using renewable energy. Its wider adoption, however, is widely considered to depend not only on ammonia-capable ships but also on a reliable supply chain, encompassing production, storage, transport and bunkering infrastructure. The absence of operational ammonia bunkering vessels has been cited as one of the gaps in that chain.

FKAB said the project demonstrates the value of designing vessels with operational flexibility, noting that having developed the original vessel design, it was able to support the conversion by preparing the technical drawing documentation. "Shenghang Yongle was designed and built as a capable, versatile working vessel," the company said. "Its conversion into an ammonia bunker vessel shows how robust naval architecture, adaptable cargo systems and carefully developed conversion documentation can help turn the marine energy transition into operational reality."