FRENCH container line CMA CGM has ordered a new engine add-on to cut methane slip from its Wärtsilä 34DF LNG engines.

CMA CGM will install the engines on eight new 9,200 teu boxships being built at Shanghai Waigaoqiao Shipbuilding. The vessels had been ordered to run on methanol, but CMA CGM later switched them to LNG in late 2023.

Each ship will operate with two six-cylinder 34DF and two nine-cylinder 34DF EnviroPac engines, as well as selective catalytic reduction systems, which strip NOx pollution from exhaust. The equipment will be delivered to the shipyard in early 2026.

Wärtsilä said the EnviroPac feature would cut methane emissions by half compared with its standard 34D — although the company would not say how, when asked by Lloyd’s List.

It added that the system would not alter the power output of 520 kW per cylinder, nor its NOx Tier III compliance.

CMA CGM newbuilding vice-president Xavier Leclercq said: “We are working hard to minimise the environmental footprint throughout our fleet, and this latest technology from Wartsila provides strong support to these efforts.”

Wärtsilä said the emission reduction would result in lower EU ETS and FuelEU penalties.

Four-stroke engines leak more unburned methane — a potent greenhouse gas — than the two-stroke engines used as main propulsion on bigger deepsea ships.

Engine makers have sought to reduce methane slip from engines in recent years, but the extent of the problem and its implications for LNG’s standing as a green fuel are still unclear.