2024, Volume 70(74), Issue 1 (January), pp. 59 - 68

Detection of High CH4 Concentrations at Natural Gas End-Use Distribution Network in Urban Areas

MUSTAFA HMOUDAH, Faculty of Environmental Science and Engineering, University of Babeş-Bolyai, Cluj-Napoca, Romania, mustafa.hmoudah@gmail.com
CRISTIAN POP, Faculty of Environmental Science and Engineering, University of Babeş-Bolyai, Cluj-Napoca, Romania
CĂLIN BACIU, Faculty of Environmental Science and Engineering, University of Babeş-Bolyai, Cluj-Napoca, Romania

pages 59 - 68   Download
DOI: 10.5281/zenodo.11145577
Abstract
Since the industrial revolution, CH4 emissions have increased by 150%. Urban Areas are responsible for approximately 60% of these emissions, mainly coming from anthropogenic activities. Besides, urbanization caused changes in land use and reduced CH4 sinks. The sources of CH4 emissions in Urban Areas still have a high degree of uncertainty. Recent studies have stated that leaks from natural gas distribution networks are significant sources of CH4 in the atmosphere, and they also represent a potential loss of energy resources. However, emissions from end-use natural gas networks are poorly explored in the literature. The main contributors in the Romanian CH4 budget are the agriculture and energy sectors. Over the period 1989–2000, methane emissions rate decreased by 34% due to sectoral changes in agriculture and fossil fuels. Nevertheless, the Romanian national inventory doesn’t report CH4 emissions from urban areas. This study investigates CH4 concentration from the end-use natural gas distribution networks in Cluj-Napoca, the second-largest city in Romania in terms of population. These points can be identified as part of the natural gas distribution networks that serve natural gas to end users for gas consumption. The detected points were pipeline junctions and natural gas meters. The estimation of CH4 concentration in the atmosphere was carried out based on a laser CH4 sensor Tunable Diode Laser Absorption Spectroscopy (TDLAS) with high measuring accuracy of 0.1 ppmv. This CH4 concentration detection was performed from December 2022 to January 2023 at 74 natural gas end-use points. The determination of whether to represent leaks or not was quite after estimating the background level in the city and comparing the obtained concentrations with this background. This study has revealed that 76% of the detected end-use natural gas distribution points have gas leaks and represent continuous contributors to CH4 annual budget. However, this contribution to the annual budget should be estimated. Moreover, the results of this study indicate the presence of high leaks from natural gas end-use points in urban areas. They suggest in-depth investigation and allocation of all natural gas leaks at the end-use points, in order to take certain reduction measures regarding CH4 mitigation.
Keywords: greenhouse gas, methane, atmosphere, urban areas, natural gas end-use networks, gas leaks.