The Methane Slip Solution: How Japan’s New Catalyst Could Clean Up LNG Shipping

A Joint Venture Tackles LNG’s Dirty Secret

LNG-fueled ships have long been touted as a greener alternative to heavy fuel oil, but they come with an invisible problem: methane slip. When unburned methane escapes engine exhaust, it’s 80 times more potent than CO2 over 20 years. Now, Mitsubishi Heavy Industries Marine Machinery & Equipment (MHI-MME) and Daihatsu Infinearth Mfg. are teaming up to solve it—with a catalytic system that turns methane into less harmful byproducts.

“This isn’t just about compliance—it’s about making LNG a genuinely sustainable fuel,” says an MHI-MME engineer involved in the project.

The system works by oxidizing methane (CH4) into carbon dioxide (CO2) and water (H2O), drastically reducing emissions. Early results are promising: onshore engine tests achieved a methane oxidation rate of at least 70%. But the real test is happening at sea. Since May, KEYS Bunkering West Japan’s LNG bunkering vessel, KEYS Azalea, has been the proving ground. Built by Mitsubishi Shipbuilding, the ship is now the first to trial the technology under real-world conditions.

Three-Way Tech Synergy

The collaboration leverages each company’s strengths: MHI-MME’s catalyst expertise, Mitsubishi Shipbuilding’s vessel integration know-how, and Daihatsu Infinearth’s engine tuning capabilities. The onboard demonstration will run for one year, monitoring performance across seasons and operational loads. If successful, it could set a new standard for LNG vessels—especially as regulators tighten methane emission rules.

“Methane slip has been the elephant in the room for LNG shipping. This system could finally address it,” notes a maritime emissions analyst.

For now, the industry is watching closely. With LNG demand growing as a bridge fuel, cutting methane slip could make or break its environmental credibility. And if the numbers hold, Japan’s joint venture might just have the key.