Abstract
Abstract. Other Test Method 33A (OTM 33A) is a near-source flux measurement method developed by the Environmental Protection Agency (EPA) primarily used to locate and estimate emission fluxes of methane from oil and gas (O&G) production facilities without requiring site access. A recent national estimate of methane emissions from O&G production included a large number of flux measurements of upstream O&G facilities made using OTM 33A and concluded the EPA National Emission Inventory underestimates this sector by a factor of ∼2.1 (Alvarez et al., 2018). The study presented here investigates the accuracy of OTM 33A through a series of test releases performed at the Methane Emissions Technology Evaluation Center (METEC), a facility designed to allow quantified amounts of natural gas to be released from decommissioned O&G equipment to simulate emissions from real facilities (Fig. 1). This study includes test releases from single and multiple points, from equipment locations at different heights, and spanned methane release rates ranging from 0.16 to 2.15 kg h−1. Approximately 95 % of individual measurements (N=45) fell within ±70 % of the known release rate. A simple linear regression of OTM 33A versus known release rates at the METEC site gives an average slope of 0.96 with 95 % CI (0.66,1.28), suggesting that an ensemble of OTM 33A measurements may have a small but statistically insignificant low bias.
Highlights
Methane is a potent greenhouse gas, and emissions from the oil and gas (O&G) sector are thought to account for roughly 30 % of total methane emissions in the United States (U.S Environmental Protection Agency (EPA), 2019)
Existing near-source studies of O&G basins suggest the majority of large, uncontrolled emissions are the result of faulty equipment that may not be noticed for some time (Zavala-Araiza et al, 2017; Omara et al, 2018), emphasizing the need for permanent or semi-permanent monitoring technologies instead of infrequent manual inspections (Coburn et al, 2018; van Kessel et al, 2018)
23 Other Test Method 33A (OTM 33A) test releases were measured during the CFTR; 21 passed the data quality indicators (DQI; U.S EPA, 2014) and were included in this analysis
Summary
Methane is a potent greenhouse gas, and emissions from the oil and gas (O&G) sector are thought to account for roughly 30 % of total methane emissions in the United States (U.S EPA, 2019). Attempts to quantify O&G methane emissions are hindered by inaccurate emission inventories, a lack of measurements, and variability between basins (Allen, 2016; Schwietzke et al, 2017; Robertson et al, 2017; Alvarez et al, 2018; Omara et al, 2018). Basin-wide aircraft measurements of methane emissions from different O&G basins find emissions are generally higher than official inventories published by the U.S Environmental Protection Agency (EPA; e.g., Karion et al, 2013; Pétron et al, 2014; Brandt et al, 2014; Karion et al, 2015; Schwietzke et al, 2017; Peischl et al, 2018), but the scale of aircraft measurements give little insight into the exact source of emissions on the ground.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
