Recent years have seen significant strides in the advancement of direct measurement technologies used to detect and quantify methane emissions from landfills. With satellites, aircraft, drones, mobile and fixed sensors, the array of technologies is growing. Since landfill emissions can present as both a point and nonpoint source of emissions, they’re more complex to measure compared to other methane sources (e.g. oil and gas facilities).
A key reason to measure methane emissions relates to detecting unknown fugitive emissions or “hotspots” from a landfill. By regulation, landfills are required to perform surface emissions monitoring, or SEM, which historically has been time consuming and intermittent. New direct measurement technologies can significantly reduce monitoring hours allowing technicians to focus on validating and mitigating hotspots and may offer more frequent measurements at potentially lower cost.
Another important reason to measure methane emissions is to quantify collective emissions from the landfill and use this to estimate annual site emissions. Such estimates are important to understand the extent to which landfills contribute to greenhouse gas emissions relative to other sources. Emission reduction is an important ESG goal for many corporate and municipally owned landfills, and new direct measurement technologies could assist in monitoring progress towards these goals.
Given these two objectives, landfill owners have been actively evaluating direct measurement technologies as a means to enhance operations and better quantify emissions. Efforts thus far include evaluating different commercially available technologies side-by-side to compare all aspects of each technology and assess measurement consistency. This technology “stacking” has advanced the industry’s functional understanding of how they can be integrated into routine operations and, perhaps most importantly, what atmospheric or site conditions impact measurement consistency.
However, the technologies have limitations that field demonstration alone only partially addresses, one of which is the accuracy of these technologies. For example, if technologies are stacked then there are potentially two outcomes:
- Their emissions estimates are reasonably close to one another (typically this would be within 20%), or
- The rates are substantially different
It is important to note that in BOTH cases, the estimates may or may not accurately reflect total site emissions. For instance, in the first outcome, it is possible that the technologies both possess a similar measurement bias where they behave identically. As a result, both could provide similarly inaccurate estimates of emissions. In the second scenario, one technology may be more accurate than another, or all could be inaccurate, and it would be difficult to ascertain which is the case without further analysis.
Understanding measurement accuracy in an absolute sense (i.e., against a standard) allows for instrumental bias to be eliminated while understanding how well certain technologies perform under varying site conditions. In this respect, while stacking technologies is a critically important evaluation strategy, it falls short.
A study initiated by the Environmental Research & Education Foundation (EREF) aims to evaluate accuracy of measurement technologies by releasing methane at a known rate. This ‘controlled release’ of methane will then be measured by multiple technologies deployed simultaneously. Such a strategy allows for absolute quantification of accuracy under identical site conditions, which serves to minimize the site and atmospheric fluctuations. This novel approach will put participating technologies on the same playing field, so to speak. “The work, conducted in collaboration with St. Xavier University (Canada), WM and multiple emissions measurement technology providers, will significantly advance the understanding of direct emissions measurement accuracy and functionality for landfills,” noted Dr. Bryan Staley, President & CEO of EREF. “St. Xavier University has conducted emissions measurement activities on nearly 100 landfills over the past year and is excited to bring our expertise to support EREF’s efforts on this study,” stated Dr. Dave Risk, Chair of the Dept. of Earth Sciences at St. Xavier.
“WM is pleased to be able to host this important study at one of our landfills,” said Bryan Tindall, Vice President of Disposal Operations, WM. “This work will produce valuable new insights regarding direct measurement of landfill methane emissions and aligns with our ongoing sustainability initiatives to develop a landfill emissions measurement system by 2025 and reduce our emissions 42% by 2032.” The field measurement campaign is expected to take place in Summer 2023 with initial results by early 2024. In addition to this work, EREF is also collaboratively engaging with the U.S. EPA, universities, landfill owners and other NGOs to aggregate data and create synergy with other efforts.