Differential Absorption Lidar (DIAL) Measurements of Landfill Methane Emissions

Abstract

Abstract:Methane is one of the most important gaseous hydrocarbon species for both industrial and environmental reasons. Understanding and quantifying methane emissions to atmosphere is therefore an important element of climate change research. Range-resolved infrared differential absorption Lidar (DIAL) measurements provide the means to map and quantify a wide range of different methane sources. This paper describes the DIAL measurement technique and reports the application of an infrared DIAL system to field measurements of methane emissions from active and closed landfill sites. This paper shows how the capability of the DIAL to measure the spatial distribution of methane plumes enables DIAL vertical scans to spatially separate and independently quantify emissions from different sources. It also allows DIAL horizontal scans carried out above the surface to identify emission hot-spots. An overview of the landfill emission surveys carried out over the last decade by the National Physical Laboratory (NPL) DIAL system is presented. These surveys were part of research projects and commercial works aimed to validate the method and to provide reliable information on the methane emissions measuring the total site and area-specific emissions from active areas, capped areas, and gas engine stacks. This work showed that methane emissions are significantly higher for active sites than closed sites due to the methane emitted directly to air from the uncapped active areas. On active sites, the operational tipping areas generally have higher emission levels than the capped areas, although there is considerably variation in the emission from different capped areas. The information obtained with DIAL measurements allow site operators to identify significant fugitive emission sources and validate emissions estimates, and they allow the regulators to revise and update the emission inventories. Operators' remediation actions driven by DIAL measurements have also been shown to considerably decreased total site methane emission.

Optical Gas Imaging (OGI) as a Moderator for Interdisciplinary Cooperation, Reduced Emissions and Increased Safety

“…The measurements were typically performed by a truck arriving on the site [13,14] and recording methane gas in the atmosphere upwind and downwind of the facility. Usually, the trucks had to be positioned within the "hot plant", i.e., where there should be no ignition sources.…”

“…The estimated CH 4 emissions for the chains as a fraction of production were 0.01-0.04%. But there are leaks, and when enforcing the regular scanning of hydrocarbon process plants in Norway, the Norwegian Environmental Agency (NEA) requires DIAL recordings, which are frequently used to record methane emissions from e.g., landfills [13] and industry areas [14]. The DIAL technique can also be used to record leaks from single units, such as large process units and storage tanks.…”

A Common Risk Classification Concept for Safety Related Gas Leaks and Fugitive Emissions?

“…Leak rates recorded by third-parties were used to issue taxes. The measurements were typically performed by a DIAL truck visiting the site [15,16] to record methane gas in the atmosphere upwind and downwind of the facility. Usually, the truck had to be positioned within the "hot plant," that is, where there should be no ignition sources.…”

“…The estimated CH 4 emissions were 0.01-0.04% of the production rate. But there are leaks and the Norwegian Environmental Agency (NEA) requires Differential Absorption Lidar (DIAL) recordings, which is also frequently used to record methane gas emissions from industry areas [15] and landfills [16]. In some special cases, the DIAL technique can also be used to record leaks from for example, large process units and storage tanks.…”

High Repetition Rate Mid-Infrared Differential Absorption Lidar for Atmospheric Pollution Detection

“…It is widely used in multiple fields including atmospheric, agricultural and industrial gas detection. At present, great progress has been made in the visible and ultraviolet spectral regions DIALs, which can determine and quantify the concentration of various gases in the atmosphere [4][5][6][7][8]. Ultraviolet DIAL uses Dye laser or Raman laser.…”