DNV on key lessons learned from a 20,000 TEU methanol retrofit delivered by global partners

Classification society DNV recently highlighted how complex methanol retrofits can be carried out in practice through a project involving COSCO Shipping, CHI Shanghai, MARIC, suppliers, and DNV. 

Its latest Maritime Impact article detailed challenges in design integration, construction, commissioning, and operations, while demonstrating how close collaboration and early planning support more efficient delivery and knowledge transfer: 

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.

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.”

Note: The full article by DNV can be read here.

Photo credit: DNV and COSCO Shipping
Published: 15 June, 2026