Mobile measurements of coal mine ventilation shafts in USCB, Poland.

In order to improve understanding and reduce methane emissions, three comprehensive measurement campaigns were conducted in June and October of 2022, as well as in June 2023. These campaigns were part of the METHANE-To-Go-Poland project, which was funded by the International Methane Emissions Observatory (IMEO) and the United Nations Environment Programme (UNEP). In addition to mobile measurements, other remote sensing techniques such as sun-viewing FTIR and hyperspectral imaging spectrometry, as well as a novel airborne approach called HELiPOD and UAV's, were deployed.

Transects were performed using Licor 7810, LGR MGGA918, or Picarro G2301i analyzers along with 2D anemometers and GPS loggers. Recognizing the significant impact of coal mines as a major source of methane emissions, these measurements aimed to enhance our understanding of the dynamics involved in methane release, contributing to ongoing efforts in addressing environmental challenges associated with coal mining.

The main focus of the campaigns was a high-emission shaft located in the Silesian Coal Basin, Southern Poland. This site had several favorable characteristics for successful measurements. The investigated ventilation shaft emitted approximately 1.5 tCH4/h of methane (based on the coal mine reporting it excavated 3457 kt of coal, which corresponds to 52.6 kt of emitted methane from the whole coal mine for the year 2021, as calculated for the national methane inventory). The shaft has good prominence, and its surroundings consist mostly of agricultural fields with intersecting roads and only a few barriers like groves and buildings.

Numerous transects were also performed at three other ventilation shafts visited during the campaigns. Emission estimates derived using an inverse Gaussian plume model ranged from 0.3±0.1 tCH4/h to 2.5±0.5 tCH4/h for these additional shafts. We attempted measurements at one of the shafts using the OTM-33A technique with the MGGA918 analyzer and a 3D anemometer. These deployments at distances exceeding 200 meters (up to 1450 meters) resulted in emission estimates ranging from 0.6±0.2 tCH4/h to 1.43±0.43 tCH4/h.

An overview of the ground-based measurements was analyzed to identify temporal variability in the emission rates from coal mine shafts. This information was also compared with measurements conducted by the coal mine operator using safety sensors (such as CH4-sensitive pellistores placed in the airflow of the ventilation shaft). A secondary goal was to compare the emission rates and measurement constraints for multiple coal mine ventilation shafts.