How much does LNG emit before it burns on a ship?

Oil and gas majors and some shipping companies present liquefied fossil natural gas (LNG) as a cleaner alternative to traditional marine fuels and a transitional fuel in shipping’s decarbonisation journey. While LNG combustion emits fewer local air pollutants and less CO₂ than conventional marine fuels, unburned methane that slips from LNG engines, especially the most polluting ones, commonly used in passenger and cruise ships, undermines its potential climate benefits. 

Whereas the uncombusted methane issue is increasingly recognised as problematic by policymakers, the upstream greenhouse gas emissions that occur during the extraction, processing, liquefaction, and transport phases of LNG largely go under the radar. Known as well-to-tank emissions, they vary considerably depending on the LNG production location, influencing the overall climate impact of LNG-fueled ships. To better quantify the effects of these upstream emissions, T&E commissioned Energy and Environmental Research Associates to research the carbon-intensity and greenhouse gas emissions from the LNG supply chain of Europe’s largest import sources.