Assessment of Technologies for Estimating Methane Destruction Removal Efficiency of Flares

Abstract

Globally, the upstream oil and gas industry flared more than 150 billion m³ of natural gas in 2024. Flaring has traditionally been assumed to oxidize nearly all high global warming potential (GWP) constituents of flare gas—chiefly methane—into carbon dioxide and water vapor, which have lower GWPs. However, increasing evidence shows this assumption is not always valid. Growing awareness of flaring’s climate impact has driven the development of performance-based regulations, voluntary reporting frameworks, and a rapidly evolving set of techniques for measuring flare emissions. These techniques may quantify emission rates directly, but more commonly assess combustion performance in terms of combustion efficiency (CE) or destruction removal efficiency (DRE) for species such as methane. The definitions of CE and DRE vary across technologies, which complicates the interpretation of these quantities, while the uncertainties associated with many estimates remain unvalidated or absent altogether. This report reviews the quantities used to characterize flare performance, explains the challenges of measuring these parameters under field conditions, surveys current and emerging measurement approaches, and concludes with a recommended procedure for establishing uncertainty in CE/DRE estimates—an essential step for ensuring that reported values are scientifically meaningful and policy-relevant. The capabilities and operating parameters of the most relevant technologies available for measuring flare emissions are summarized in an annex.