All ships that use an internal combustion engine with LNG let more or less methane escape into the air depending on the engine type. This includes the five Wartsila 4-stroke 14V46DF engines the MSC World Europa is equipped with, says an article published on Transport&Environment.
Methane EscapeThe IMO estimates that this type of four-stroke, low pressure engine lets on average 3.5% of methane escape into the air. The European Union, on the other hand, estimates that...
https://mfame.guru/filming-of-methane-slips-onboard-the-msc-world-europa/