The milestone that bridges innovation and reality

Workers clad in red and blue coveralls are piecing together dozens of gigantic cargo ships bound for customers all over the world. Engineers, welders, forklifts, trucks, and cranes move massive components through HD Hyundai Heavy Industries’ (HHI) vast shipyard here in Ulsan, on the southeastern coast of South Korea. For an outsider visiting the complex, the scale is hard to grasp. 

But even here, the recent transport of the first Everllence dual-fuel ammonia engine from test bed to ship hull stood out—and not simply for its size. For the maritime industry, the move represents a crucial step toward operating large commercial vessels on ammonia fuel.

Shipping’s fuel dilemma

Shipping has struggled to wean itself off heavy fuel oil (HFO), the fossil fuel that has powered much of the global fleet for more than a century. International shipping produces roughly 3 percent of global CO₂ emissions — more than one billion metric tons each year — and left unchecked, its share stands to grow as global trade expands.

Methanol and liquefied natural gas (LNG) have already gained traction as low-carbon fuels in shipping, particularly in dual-fuel engines. But ammonia is increasingly attracting attention because it contains no carbon and, when produced using renewable energy, offers a potential pathway to near-zero-emission shipping.

That transition is already taking shape at Ulsan shipyard. A Very Large Ammonia Carrier (VLAC) under construction for Eastern Pacific Shipping is set to be the first vessel  powered by the Everllence B&W 6G60ME-LGIA dual-fuel ammonia engine.

From test bed to ammonia-powered vessel

The 6G60ME-LGIA engine weighs several hundred tons and stands nearly three stories tall, dwarfing the engineers around it. First developed as a concept at Everllence’s Research Centre Copenhagen (RCC), it is the product of more than 150,000 engineering hours dedicated to solving one of ammonia propulsion’s central challenges: how to reliably combust a slow-burning fuel in a large marine engine.

Building on decades of dual-fuel engine experience, engineers developed new fuel-injection systems, engine controls, and combustion strategies before validating the design through extensive full-scale testing at MITSUI E&S in Japan and delivery of the first ammonia engine by HHI in Korea.

“We began collaborating with Everllence on the development of this ammonia engine from the early stages of the project,” says Seongwoo Choi, Senior Engineer and Head of Two-Stroke Engine Design at HHI’s Engine Machinery Division (HHI-EMD). “HHI-EMD and Everllence worked closely — not only on the engine design but also on preparing the facilities and ammonia supply systems needed for R&D testing and Factory Acceptance Testing.”

In one corner of the Ulsan shipyard, a self-propelled Kamag modular transporter rolled toward the hangar where the engine had successfully completed Factory Acceptance Test (FAT), the final milestone before delivery. Guided by a remote operator, the 96-wheeled platform maneuvered into position as the engine’s lower section — wrapped in green tarp — was loaded for transport to the drydock.

There, a giant crane lifted the lower section into the engine room deep inside the hull of the ammonia carrier. Later that day, the remaining sections followed. Inside the vast hull of the VLAC, the engine that had dominated the test hall suddenly appeared almost small against the scale of the ship around it.

“This isn’t just the introduction of a new engine,” says Donghwan Kim, Sales Promotion Manager at Everllence. “It’s a moment of theory becoming reality. For years, ammonia has been considered a theoretical solution for decarbonization. By successfully installing the ME-LGIA engine, we are proving that zero-carbon propulsion is more than just a concept on paper. It’s a realistic net-zero solution for the marine industry.”

Engineering safety for ammonia propulsion

“The ME-LGIA was developed from the existing LGI platform, so many of the core gas injection concepts are based on technologies already proven in other dual-fuel engines,” says Choi. However, bringing ammonia propulsion to sea does introduce major engineering and safety challenges. 

Although ammonia has long been transported aboard liquefied gas carriers, it has not previously been at scale as a marine fuel because of its toxicity. In enclosed spaces such as engine rooms and pump rooms, even a relatively small leak can pose a risk to crew members.

“Safety has guided the ME-LGIA design from the start,” says Choi. “Because ammonia is toxic, we’ve introduced multiple safety layers, including leak detection, ventilation, purging systems, and failsafe controls.”

Additional safety measures include containment systems, sensors, system ventilation, and double-walled piping developed especially for ammonia fuel applications. 

Ammonia also produces nitrogen oxides (NOx). To counter this, the ME-LGIA is equipped with High Pressure Selective Catalytic Reduction (HP-SCR) technology, an exhaust aftertreatment system designed to remove up to 95 percent of NOx formed during combustion. 

Shipyards handling ammonia propulsion also require major changes, says Kim, including advanced fuel-gas supply systems (FGSS) to manage the safe storage and delivery of ammonia onboard, as well as precise leak detection and emergency mitigation systems, and specialized safety, welding, and handling procedures.

The next step for ammonia-powered shipping

Kim views the project as a good example of collaboration between the engine designer, the engine builder, the shipyard, and the ship owner, each solving different parts of the challenge — from combustion stability, reliability, and onboard safety to vessel integration and regulatory compliance. 

After engine delivery, the VLAC undergoes a roughly six-month buildout before sea trials begin. Once delivered in late 2026, the vessel will both transport ammonia cargo and operate using ammonia fuel. According to Choi, the next phase will be demonstrating the engine’s performance under real-world sailing conditions.

“The testing and installation of the engine signals that the wait-and-see period is coming to an end,” says Kim. “For many shipowners, the successful installation and test of ammonia engines removes the psychological barrier. This shifts the market conversation on ammonia as a fuel from ‘Can we do it?’ to ‘When should we order?’”

“Installing this engine is a meaningful moment because years of development and testing have now reached a real ship and real operations,” says Choi. “At the same time, this is not the end, but the beginning of putting the engine into actual service. ”

About the author

Timothy Hornyak is a Tokyo-based author and journalist covering technology, business, and culture in Asia.