Mega-boxship successfully converted to dual-fuel methanol operation

DNV says the successful methanol conversion of the 20,000-TEU containership COSCO Shipping Libra demonstrates that meaningful decarbonisation of existing fleets is already technically achievable, following one of the largest low-carbon fuel retrofits undertaken in the container sector.

The vessel, a seven-year-old mega-boxship, underwent conversion at a Shanghai shipyard in 2025 as part of a project involving COSCO Shipping, CHI Shanghai, MARIC, equipment suppliers and DNV. The retrofit transformed the vessel from conventional fuel operation to dual-fuel methanol operation, providing a practical blueprint for future large-scale conversions.

The work included converting the MAN B&W 11S90 main engine and two of the vessel's four Wärtsilä auxiliary engines to operate on methanol. New methanol storage tanks with a combined capacity of more than 15,000m3 were installed forward of the engine room, alongside fuel preparation and supply systems required for safe methanol handling and operation.

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

For COSCO Shipping, the project formed part of a broader strategy to reduce emissions from existing tonnage while continuing to invest in newbuildings. However, the conversion came with operational trade-offs, including the loss of 456 TEU of cargo capacity to accommodate methanol tanks and associated systems.

"Retrofitting allows us to act now, but it also comes with trade-offs that have to be understood and managed," said Zhang Jun, Safety Supervision manager in COSCO Shipping Lines' Technology & Innovation Department.

Since returning to service, COSCO Shipping Libra has operated successfully on methanol, while retaining the flexibility to switch between fuels. DNV said the project delivered valuable operational experience for the owner, established repeatable retrofit processes for the shipyard, and demonstrated that substantial emissions reductions from existing vessels can be achieved using currently available technology.

The news follows this month’s completion of a methanol retrofit on the smaller Seaspan Yangtze, which had its own MAN S90 engine retrofitted to dual-fuel methanol operation.