Global methane emissions from natural gas networks

Abstract

Given the significant global warming power and short atmospheric lifetime of methane, one of the most effective mitigation strategies for limiting global warming over the short term is to target the anthropogenic sources of methane and rapidly reduce their emissions. The unaccounted for gas phenomenon in natural gas transmission and distribution networks reflects an imbalance between what enters the gas network and what leaves it. The aim of this paper is to investigate the possibility of leaks along these gas networks, and to determine whether this leads to methane emissions, since natural gas is mainly composed of methane. First, flow data measured along gas networks are collected and used to assess unaccounted for gas by country. A global average value of 1.7% is observed, but with significant disparities between regions ranging from 0.01% to 15%. Second, unaccounted for gas values permit to assess the quantities of methane released into the atmosphere by gas networks. In total, 18 Mt of methane were emitted in 2021. The main producing countries present high unaccounted for gas volumes and methane emissions, which can be explained by the age of their gas networks. Conversely, networks in more recent markets or advanced countries have fewer leaks, leading to more moderate methane emissions. This shows than methane emissions can be reduced in well-maintained networks. The accounting method developed in this article would make it possible to verify the emissions reductions announced for gas networks in the future if repeated over time.