Methane Leaks from North American Natural Gas Systems
Abstract
Natural gas (NG) is a potential “bridge fuel” during transition to a decarbonized energy system: It emits less carbon dioxide during combustion than other fossil fuels and can be used in many industries. However, because of the high global warming potential of methane (CH4, the major component of NG), climate benefits from NG use depend on system leakage rates. Some recent estimates of leakage have challenged the benefits of switching from coal to NG, a large near-term greenhouse gas (GHG) reduction opportunity (1–3). Also, global atmospheric CH4 concentrations are on the rise, with the causes still poorly understood (4).
To improve understanding of leakage rates for policy-makers, investors, and other decision-makers, we review 20 years of technical literature on NG emissions in the United States and Canada [see supplementary materials (SM) for details]. We find (i) measurements at all scales show that official inventories consistently underestimate actual CH4 emissions, with the NG and oil sectors as important contributors; (ii) many independent experiments suggest that a small number of “superemitters” could be responsible for a large fraction of leakage; (iii) recent regional atmospheric studies with very high emissions rates are unlikely to be representative of typical NG system leakage rates; and (iv) assessments using 100-year impact indicators show system-wide leakage is unlikely to be large enough to negate climate benefits of coal-to-NG substitution.
Authors
A. R. BRANDT , G. A. HEATH, E. A. KORT, F. O'SULLIVAN, G. PÉTRON, S. M. JORDAAN, P. TANS, J. WILCOX, A. M. GOPSTEIN, D. ARENT, S. WOFSY, N. J. BROWN, R. BRADLEY, G. D. STUCKY, D. EARDLEY, AND R. HARRISS