Integrating Technical Economic and Management Requirements for Successful Measurement Informed Inventory: A Case Study

There have been persistent indications that emissions estimates for facilities derived from bottom-up (BU) inventories disagree with emissions estimates from top-down (TD) observations using aircraft or mobile methods at either the facility or basin scale. This has driven increased interest in using TD observations to enhance inventory estimates, a process commonly known as measurement-informed inventory (MII). While multiple voluntary reporting programs integrate MII methods, little research has confirmed the practical implementation of such estimates or assessed the efficacy of the methods. This study evaluated MII methods at midstream facilities by deploying two TD aerial methods to inform a traditional BU inventory. The BU inventory used activity and emission factors, following an enhanced Greenhouse Gas Reporting Program (GHGRP) methodology. The study highlighted challenges in implementing MII at midstream facilities, including significant disagreement in TD methods (up to 2:1), discrepancies between TD and operator estimated inventory (OEI), limited use of measurements to improve inventories due to confusion and distrust, and underestimated analysis costs, often matching the expense of TD surveys. Results from this study show both the potential of MII methods and the current challenges associated with implementing them.