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Browsing Research Data - Other by Subject "Methane"

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    Dataset associated with "A cautionary report of calculating methane emissions using low-cost fence-line sensors"
    (Colorado State University. Libraries, 2022) Riddick, Stuart; Ancona, Riley
    Methane is emitted during extraction, processing, and transport processes in the natural gas industry. As a powerful greenhouse gas, methane releases are harmful to the environment. Operators aim to minimize methane loss, and continuous monitoring using low-cost fence-line sensors are now being developed to observe methane enhancements downwind of operations. However, it is not clear how useful these systems are and whether they can be used to quantify emissions or simply identify the presence of a leak. To investigate this, we deployed four calibrated low-cost sensors 30 m from emissions of known rates over a 48-hour period. The aims were to determine: 1) how much of the time a fence-line system would detect a leakage event from a single, point source of the size typically seen at oil and gas production well pads; and 2) how accurately a fence-line system can estimate emissions using a relatively simple downwind dispersion method. Our results show that during the 48-hour measurement period the sensors could detect mixing ratios greater than an enhancement threshold of 2 ppm for methane releases of 84 g h-1 40% of the time, 100% of the time for emissions of 167 g h-1 and 100% of the time downwind of the 313 g h-1. We show that emissions can be overestimated by as much as 4 x 10102 times using a simple Gaussian plume equation, which was attributed to the inability of the equation to parameterize lateral dispersion at distances less than 100 m. Using two other methods, near real-time average emissions can be calculated to be within 23% of a known emission rate of the source, however individual emissions can vary by -100% and +1,885%. This study provides evidence to support the use of low-cost sensors as autonomous fence-line monitoring systems to detect and potentially quantify emissions. If the sensors are properly calibrated and sensor deployment location is optimized for prevailing wind directions at each site, fence-line systems could be used routinely to quantify emissions from oil and gas infrastructure.