Mitsui O.S.K. Lines (MOL) says it has achieved a 98% reduction in methane slip during onboard trials on an LNG-fuelled vessel.

The demonstration began in May 2025 aboard the large coal carrier Reimei, which operates between Japan and Australia. MOL said the result comfortably exceeded its target of 70% and also improved on the 93.8% recorded in land-based tests in 2024.

This was achieved using a methane-oxidation catalyst system developed in collaboration with Kanadevia Corporation and Yanmar Power Technology Co., Ltd. The setup places a catalyst in the exhaust pipe of LNG-fuelled engines or generators to oxidise unburned methane, while combining it with exhaust gas recirculation (EGR) can further improve performance, according to MOL.

The work was selected under the New Energy and Industrial Technology Development Organization’s ‘Development of Next-Generation Vessels’ programme.

MOL stated that the catalyst system, adapted from land-based testing for onboard use, maintained a high reduction rate despite changing weather, engine-room conditions and engine loads during actual voyages.

The Japanese shipowner plans to continue onboard trials through the end of fiscal 2026 to assess catalyst durability and overall system performance, with the aim of introducing the technology from fiscal 2027.

The latest results follow MOL’s recent installation of dual Wind Challenger sails on an LNG carrier under construction, as the group continues testing technologies aimed at reducing emissions from gas-fuelled tonnage.