Tokyo-based classification society ClassNK has issued an Approval in Principle (AiP) for a methane oxidation catalyst system developed by Mitsubishi Heavy Industries Marine Machinery & Equipment Co., Ltd. and Mitsubishi Shipbuilding Co., Ltd..
The AiP confirms the system’s feasibility from regulatory and safety perspectives, marking a step forward in addressing methane slip from LNG-fuelled engines—a key challenge in maritime decarbonisation.
Methane slip refers to unburned methane released during combustion, a significant concern given methane’s high global warming potential. The catalyst system is designed to oxidise methane in engine exhaust streams, thereby reducing emissions.
The technology has already been installed as a demonstration unit onboard the LNG bunkering vessel KEYS Azalea, where it is undergoing operational testing.
ClassNK conducted its review based on Chapter 21, Part D of its Rules and Guidance for the Survey and Construction of Steel Ships, confirming that the design meets applicable requirements. The AiP indicates that the concept is technically viable for marine application, while also helping to streamline future classification approvals and reduce potential redesign work.
As LNG remains a transitional marine fuel, solutions targeting methane slip are gaining traction as the industry seeks to improve the overall emissions profile of gas-fuelled vessels.
ClassNK said it will continue to support decarbonisation through safety assessments and certification of emerging technologies, including systems aimed at reducing greenhouse gas emissions.
