Understanding the Accuracy Limitations of Quantifying Methane Emissions Using Other Test Method 33A
Understanding the Accuracy Limitations of Quantifying Methane Emissions Using Other Test Method 33A
复制标题
DOI：
10.3390/environments9040047
复制
发表时间：
2022-04-01
期刊：
影响因子：
3.7
通讯作者：
Abdul-Aziz, Omar, I
中科院分区：
文献类型：
--
作者：
Heltzel, Robert;Johnson, Derek;Abdul-Aziz, Omar, I
研究人员利用其他测试方法（OTM）33 A来量化天然气基础设施的甲烷排放量。从历史上看，与已知的甲烷受控释放相比，根据大量测量结果报告了错误。这些误差被报告为+/-70%的2 σ误差。然而，很少有研究已经进行的任何一个测量的最小可达到的不确定度。我们提出了两种方法的不确定性估计。第一个是最先进设备的测量不确定性，确定为估计值的+/- 3.8%。这是通过自举测量与控制释放相比较来确定的。第二种不确定性估计方法是改进的Hollinger和Richardson（H&R）方法，该方法用于量化涡度相关测量的不确定性。使用该方法的修改版本应用于OTM 33 A测量，确定任何给定测量的不确定度为+/-17%。将测量不确定性与随机性相结合，产生了17.4%的总最小不确定性。由于目前固定的单传感器测量的性质和大气数据的随机性，这种不确定性将始终存在。这对于理解甲烷排放的传输和从天然气工业获得的间接测量至关重要。
Researchers have utilized Other Test Method (OTM) 33A to quantify methane emissions from natural gas infrastructure. Historically, errors have been reported based on a population of measurements compared to known controlled releases of methane. These errors have been reported as 2 sigma errors of +/- 70%. However, little research has been performed on the minimum attainable uncertainty of any one measurement. We present two methods of uncertainty estimation. The first was the measurement uncertainty of the state-of-the-art equipment, which was determined to be +/- 3.8% of the estimate. This was determined from bootstrapped measurements compared to controlled releases. The second approach of uncertainty estimation was a modified Hollinger and Richardson (H&R) method which was developed for quantifying the uncertainty of eddy covariance measurements. Using a modified version of this method applied to OTM 33A measurements, it was determined that uncertainty of any given measurement was +/- 17%. Combining measurement uncertainty with that of stochasticity produced a total minimum uncertainty of 17.4%. Due to the current nature of stationary single-sensor measurements and the stochasticity of atmospheric data, such uncertainties will always be present. This is critical in understanding the transport of methane emissions and indirect measurements obtained from the natural gas industry.