NYK tests methane slip reduction system on LNG bunker vessel

Japanese shipping firm NYK Line said it has cut methane slip by 90% on an LNG dual-fuel bunker vessel.

IMAGE: The LNG dual-fuel LNG bunker vessel KEYS Azalea. Ithochu Enex

NYK Line has installed a methane oxidation catalyst system on the Keys Azalea, an LNG dual-fuel bunker vessel owned by Keys Bunkering West Japan and operating in Japan's Kyushu and Seto Inland Sea regions.

The system was developed by Mitsubishi Heavy Industries Marine Machinery & Equipment, Mitsubishi Shipbuilding and Daihatsu Infinearth.

Methane slip occurs when part of the methane used as fuel is released into the atmosphere without being fully burned inside the engine. Although LNG can reduce CO2 emissions compared to conventional marine fuels, methane is a far more potent greenhouse gas.

In the EU’s FuelEU Maritime regulation, Otto medium speed LNG engines have a default methane slip of 3.1%. At the other end of the range, diesel slow speed LNG engines have a default methane slip of 0.2%.

NYK Line's installed catalyst system is designed to reduce methane slip by treating exhaust gases before they are released from the vessel. It converts unburned methane into CO2 and water.

Earlier land-based tests showed the system could remove at least 70% of methane from exhaust gases. The first onboard measurements pushed that figure above 90%, according to NYK Line.

It should be noted that the 90% figure reflects initial onboard measurements taken during an ongoing trial on a single vessel, and cannot be interpreted as a fixed methane reduction rate across all vessel segments with different engine types.

The bunker vessel will continue to test the full-scale prototype as part of a one-year trial. NYK Line will assess the system’s performance under real operating conditions and whether it is suitable for broader commercial use.

By Konica Bhatt

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