Retrofitting at scale: Lessons from delivering the world’s first methanol mega containership conversion

The world’s first methanol conversion project for a mega container carrier was completed at CHI‑Shanghai’s yard in September 2025. At nearly 400 metres in length and with a capacity of 20,000 TEU, the seven‑year‑old vessel became the first ship of its kind to be retrofitted to run on methanol.

Delivered through close coordination between COSCO Shipping, CHI Shanghai, designers, suppliers, and DNV, and supported by a process of continuous learning, the project demonstrated that deep, first‑of‑a‑kind retrofits can be executed safely, on time, and at industrial scale.

Designing a methanol conversion for a megaship

The vessel’s fuel system, designed only for conventional fuels, required fundamental changes to enable safe and compliant methanol operation across propulsion, auxiliaries, storage, and safety systems.

The general design was developed by MARIC, while CHI Shanghai carried out the detailed engineering and served as EPC contractor. The scope included conversion of the ship’s MAN B&W 11S90 main engine and two of its four Wärtsilä auxiliary engines to dual‑fuel operation. In parallel, new methanol fuel tanks with a total capacity exceeding 15,000 cubic metres were installed forward of the engine room, together with new fuel preparation and supply systems.

At CHI Shanghai Shipyard, a 20,000-TEU container ship was converted to methanol propulsion for the first time anywhere in the world.

Coordinating the complexity of retrofitting

Delivering this as a retrofit rather than a newbuild added complexity that is often underestimated. Existing structural arrangements could not simply be replaced, and new systems had to be integrated into confined spaces, requiring innovative construction sequences and tight interface management between suppliers.

“This was a very complex project involving many parties, including engine makers, fuel system suppliers, and automation and safety specialists,” says Yan Hao, Commercial Director at CHI‑Shanghai. “It was also the first time all of these suppliers had worked together on a methanol retrofit of this scale. Coordination was critical.”

Why phased construction proved more efficient

One of the earliest technical decisions illustrated how established assumptions had to be challenged. The original plan envisaged fabricating the methanol fuel tank and preparation room as a single integrated block, to be lifted and installed on board. In practice, this proved impractical due to extensive high-altitude work and its impact on yard productivity.

Instead, the yard adopted a phased construction strategy.

“This involved assembling major components at ground level before integrating them into the vessel,” says Yan. “The change improved safety, reduced installation risk, and ultimately proved more efficient."

Applying first vessel lessons cuts methanol retrofit yard time by weeks

Commissioning posed even a greater challenge. Converting engines to methanol operation is not simply a mechanical exercise. Control systems, automation layers, and remote-operation interfaces must function seamlessly under operating conditions that differ significantly from conventional fuels.

"For the first vessel, software commissioning took far longer than expected," Yan explains. "Because this was a fist-of-its-kind retrofit involving several suppliers, there was no baseline data. The integration of multiple systems required extensive testing and recalibration.

The result was a total yard stay of 108 days for COSCO SHIPPING Libra, including eight days of sea trials. When the sister vessel COSCO SHIPPING Gemini entered the yard later the same year, the same core team was able to apply lessons learnt from the first project. This resulted in completing the retrofit in just 90 days, demonstrating clear efficiency gains.

Early class engagement underpins safe and compliant methanol retrofits

Alongside the physical work in the yard, the project was shaped by extensive preparatory efforts well before the vessel arrived in drydock. Given the novelty and scale of the conversion, close engagement with class was essential to ensure that safety, compliance, and operability were addressed alongside engineering needs.

DNV supported the project through early design reviews and, system-integration discussions and approval processes, working closely with the owner, yard, and suppliers. This included building methanol‑specific competence within the local survey team well in advance of the conversion.

“For a project like this, early preparation is essential,” says Boris Bondarenko, Senior Vice President and Area Manager China FiS Maritime, at DNV. “This means assessing how entirely new fuel systems, engines, automation, and safety concepts interact on an existing vessel.”

Throughout retrofit and sea trials, class oversight focused on the integration of methanol systems into the vessel’s architecture and the management of operational and safety risks. The experience has since informed subsequent methanol and LNG retrofit projects.

Yard Vice general manager Jeffrey Yu is handing over appreciation letter to Central FiS manager Chang Shao You.

The owner’s perspective: From concept to operation

For COSCO Shipping, the decision to pursue a methanol retrofit was both strategic and practical. While newbuilds remain central to fleet renewal, the company recognized that existing tonnage must also be addressed to meet decarbonization targets.

“Retrofitting allows us to act now,” says Zhang Jun, Safety Supervision Manager, Technology & Innovation Department, COSCO Shipping Lines, Co., Ltd. “But it also comes with trade‑offs that have to be understood and managed.”

One visible consequence was reduced container capacity. To accommodate methanol tanks and systems COSCO Shipping Libra lost 456 TEU, requiring careful reassessment of deployment and network planning.

Fuel availability and handling were also key considerations. While methanol infrastructure is developing rapidly on major trade lanes, it remains less mature than conventional fuels. Operational teams had to adapt to new bunkering procedures, safety protocols, and fuel‑management practices.

“At the operational level, the learning curve is real,” Jun explains. “Crew training, maintenance planning, and fuel logistics all have to evolve together.”

Early operational experience

Since re‑entering service, COSCO SHIPPING Libra has demonstrated stable operation on methanol, giving COSCO confidence in the technical solution. Dual‑fuel capability allows the vessel to switch fuels as required, offering flexibility during early deployment.

“The project showed that even very large, modern container ships can be converted successfully,” Jun says. “That changes how we think about the future of the fleet.”

At the same time, the company remains realistic about limitations. Methanol fuel injectors and certain sealing systems still face durability challenges, and long-term lifecycle data is still emerging, reinforcing the need for further close collaboration with yards, suppliers, and class.

Scaling retrofit capability in China

From the yard’s perspective, the COSCO project has become a reference point for managing complexity at scale.

CHI Shanghai has since applied similar methodologies to other projects, including multi‑vessel methanol retrofits for Seaspan and potential LNG retrofits for MSC and COSCO Shipping. While individual projects differ, the underlying approach, such as detailed design ownership, phased construction, and intensive integration testing, remains consistent.

The yard has also adopted a “shipbuilding model” for retrofits, integrating design, construction, and commissioning under a single EPC framework, reducing interface risk and improving knowledge transfer.

Future proofing in an uncertain fuel landscape

Both owner and yard emphasize that methanol retrofits must be designed with flexibility in mind. Fuel strategies remain in flux, shaped by regulation, availability, and cost dynamics.

At CHI Shanghai, this has translated into preserving original fuel systems where possible, ensuring automation compatibility, and minimizing cargo‑capacity loss. COSCO shares this pragmatic view.

“We expect multiple alternative fuels to coexist,” Jun notes. “The key is flexibility, not betting everything on a single outcome.”

DNV project manager Xiang Hui is attending the commissioning along with technicians and yard personal at sea trial.

From prototype to pathway

“The significance of the COSCO Shipping Libra retrofit lies less in its status as a “first” but more in what it enabled. By converting a technically demanding megaship, the project demonstrated a credible pathway for large‑scale methanol retrofitting,” Jan-Olaf Probst, Segment Director Containerships at DNV acknowledges.

For the yard, it accelerated the development of repeatable processes. For the owner, it delivered real‑world operational insight. And for the wider industry, it showed that significant, meaningful decarbonization of existing fleets is achievable as a present‑day engineering reality.

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