Testing Begins for System to Address Methane Slip from LNG Marine Engines

Testing is getting underway for an onboard system installed on an in-service LNG bunker vessel to address methane slip. The release of unburnt methane is one of the critical challenges facing LNG operations, with environmentalists highlighting that methane is one of the most potent greenhouse gas emissions.

The LNG industry assets that the newest generation of LNG marine engines are far more successful at reducing methane emissions. Researchers, at the same time, have been working to develop systems that could address the emissions to improve the long-term prospects for LNG.

Japan’s Mitsubishi Heavy Industries Marine Machinery & Equipment Co. reports working with Daihatsu Infinearth Mfg. Co. and its engine optimization technology, the companies developed a methane oxidation catalyst system. Onshore test equipment for the methane oxidation catalyst system for marine LNG engines showed promising results with a verified initial methane oxidation rate of 70 percent or higher.

In the next phase of the demonstration tests, the companies working with KEYS Bunkering West Japan installed the system on an in-service vessel. Testing began in May aboard the KEYS Azalea, a 2,352 dwt LNG bunkering vessel built in 2024 by Mitsubishi Shipbuilding. KEYS Azalea completed its first bunking in Hiroshima in April 2024 and provides domestic coastal transport of LNG to consumers in the Kyushu and Setouchi areas and LNG bunkering for oceangoing ships calling ports in the region.

The catalyst system for the demonstration test oxidizes slip methane contained in the exhaust gas of marine engines. Methane oxidation, the companies explained, is a chemical reaction in which methane (CH4) is converted into carbon dioxide (CO2) and water (H2O) through reaction with oxygen.

Demonstration testing will be conducted continuously for the next year as part of MHI Group’s strategic efforts to strengthen its energy transition business. MHI-MME and Mitsubishi Shipbuilding are a part of this strategy, and amid the increasing urgency for global decarbonization, the company says it will continue to work to reduce GHG emissions from marine vessels and contribute to the improvement of the environmental performance of ships on a global scale.