Multiscale Measurements of Greenhouse Gas Emissions at U.S. Natural Gas Liquefaction Terminals.

Addressing methane emissions across the liquefied natural gas (LNG) supply chain is key to reducing climate impacts of LNG. Actions to address methane emissions have emphasized the importance of the use of measurement-informed emissions inventories given the systematic underestimation in official greenhouse gas (GHG) emission inventories. Despite significant progress in field measurements of GHG emissions across the natural gas supply chain, no detailed measurements at US liquefaction terminals are publicly available. In this work, we conduct multiscale, periodic measurements of methane and carbon dioxide emissions at two US LNG terminals over a 16-month campaign. We find that methane emission intensity varied from 0.007% to 0.045%, normalized to methane in LNG production. Carbon dioxide emissions accounted for over 95% of total GHG emissions using 100-year global warming potential (GWP) for methane. Thus, contrary to observations across other natural gas supply chain segments, we find that reported GHG emissions intensity closely matches measurement informed GHG emissions intensity of 0.24-0.27 kg CO₂e/kg CH₄. In the context of developing LNG supply chain emissions intensity, we conclude that the use of the Greenhouse Gas Reporting Program emissions intensity provides reasonably accurate estimates of total GHG emissions at LNG terminals.