Coal Mine Methane Emissions Research Articles

High-resolution satellite estimates of coal mine methane emissions from local to regional scales in Shanxi, China

Coal mines are significant anthropogenic sources of methane emissions, detectable and traceable from high spatial resolution satellites. Nevertheless, estimating local or regional-scale coal mine methane emission intensities based on high-resolution satellite observations remains challenging. In this study, we devise a novel interpolation algorithm based on high-resolution satellite observations (including Gaofen5-01A/02, Ziyuan-1 02D, PRISMA, GHGSat-C1 to C5, EnMAP, and EMIT) and conduct assessments of annual mean coal mine methane emissions in Shanxi Province, China, one of the world's largest coal-producing regions, spanning the period 2019 to 2023 across various scales: point-source, local, and regional. We use high-resolution satellite observations to perform interpolation-based estimations of methane emissions from three typical coal-mining areas. This approach, known as IPLTSO (Interpolation based on Satellite Observations), provides spatially explicit maps of methane emission intensities in these areas, thereby providing a novel local-scale coal mine methane emission inventory derived from high-resolution top-down observations. For regional-scale estimation and mapping, we utilize high-resolution satellite data to complement and substitute facility-level emission inventories for interpolation (IPLTSO+GCMT, Interpolation based on Satellite Observations and Global Coal Mine Tracker). We evaluate our IPLTSO and IPLTSO+GCMT estimation with emission inventories, top-down methane emission estimates from TROPOMI observations, and TROPOMI's methane concentration enhancements. The results suggest a notable right-skewed distribution of methane emission flux rates from coal mine point sources. Our IPLTSO+GCMT estimates the annual average coal mine methane emission in Shanxi Province from 2019 to 2023 at 8.9 ± 0.5 Tg/yr, marginally surpassing top-down inversion results from TROPOMI (8.5 ± 0.6 Tg/yr in 2019 and 8.6 ± 0.6 Tg/yr in 2020). Furthermore, the spatial patterns of methane emission intensity delineated by IPLTSO+GCMT and IPLTSO closely mirror those observed in TROPOMI's methane enhancements. Our comparative assessment underscores the superior performance and substantial potential of the developed interpolation algorithm based on high-resolution satellite observations for multi-scale estimation of coal mine methane emissions.

Unveiling Unprecedented Methane Hotspots in China's Leading Coal Production Hub: A Satellite Mapping Revelation

AbstractChina is likely the world's largest anthropogenic source of methane emissions, with coal mine methane (CMM) being the predominant contributor. Here, we deploy 2 years of satellite observations to survey facility‐level CMM emitters in Shanxi, the most prolific coal mining province in China. A total of 138 detected episodic events at 82 facilities are estimated to emit 1.20 (+0.24/−0.20, 95% CI) million tons of methane per year (Mt CH4/yr) during 2021–2023, roughly equivalent to 4.2 times the integrated flux from the Permian plumes and four times of the integrated flux from the Four Corners plumes, two of the world's largest hotspots for oil and gas methane emissions. This work reveals the heavy‐tailed distribution characteristic of CMM emission sources for the first time, with 20% of emitters contributing approximately 50% of total emissions. Comparison with the Global Energy Monitor (GEM) inventory reveals that the GEM estimate is about 4.1 times our estimate.

Quantifying CH4 emissions from coal mine aggregation areas in Shanxi, China, using TROPOMI observations and the wind-assigned anomaly method

Abstract. China stands out as a major contributor to anthropogenic methane (CH4) emissions, with coal mine methane (CMM) playing a crucial role. To control and reduce CH4 emissions, China has made a dedicated commitment and formulated an ambitious mitigation plan. To verify the progress made, the consistent acquisition of independent CH4 emission data is required. This paper aims to implement a wind-assigned anomaly method for the precise determination of regional-scale CMM emissions within the coal-rich Shanxi province. We use the TROPOspheric Monitoring Instrument (TROPOMI) CH4 observations from May 2018 to May 2023, coupled with ERA5 wind and a bottom-up inventory dataset based on the IPCC (Intergovernmental Panel on Climate Change) Tier 2 approach covering the Changzhi, Jincheng, and Yangquan regions of the Shanxi province. The derived emission strengths are 8.4 × 1026 molec. s−1 (0.706 Tg yr−1, ±25 %), 1.4 × 1027 molec. s−1 (1.176 Tg yr−1, ±20 %), and 4.9 × 1026 molec. s−1 (0.412 Tg yr−1, ±21 %), respectively. Our results exhibit biases of −18 %, 8 %, and 14 %, respectively, when compared to the IPCC Tier 2 bottom-up inventory. Larger discrepancies are found when comparing the estimates to the Copernicus Atmosphere Monitoring Service global anthropogenic emissions (CAMS-GLOB-ANT) and Emissions Database for Global Atmospheric Research (EDGARv7.0) inventories (64 %–176 %), suggesting that the two inventories may be overestimating CH4 emissions from the studied coal mining regions. Our estimates provide a comprehensive characterization of the regions within the Shanxi province, contribute to the validation of emission inventories, and provide additional insights into CMM emission mitigation.

Methane mitigation potentials and related costs of China's coal mines

Mitigating methane (CH4) emissions from China's coal mines as the largest contributor to anthropogenic CH4 emissions is vital for limiting global warming. However, the knowledge about CH4 mitigation potentials and economic costs of Chinese coal mines remain poorly understood, which hinders the formulation of tailored CH4 mitigation strategies. Here, we estimate and project China's provincial coal mine methane (CMM) emissions, mitigation potentials and costs under various coal production scenarios, by integrating the dynamic emission factors of CMM and key abatement technologies. We find that through continuous coal cuts and available CMM mitigation measures, China's CMM emissions can be reduced by 65%-78% (10.9 Tg-13.1 Tg) in 2060, compared with the 2021 level. CH4 emissions from abandoned coal mines will far exceed those from coal mining under the 2060 carbon-neutral scenario, especially in northeastern China. It was also found that CMM mitigation is not economically feasible at present, but may be the most cost-effective solution as CO2 prices increase. All coal-producing provinces can achieve CMM mitigation below 50 RMB/t CO2e in 2060. Inner Mongolia is identified as a hotspot for CMM mitigation with huge potential and lower cost. Our prospective assessment can provide insights into China's CMM mitigation in response to climate change.

High-resolution assessment of coal mining methane emissions by satellite in Shanxi, China

Accurate assessment of coal mine methane (CMM) emissions is a prerequisite for defining baselines and assessing the effectiveness of mitigation measures. Such an endeavor is jeopardized, however, by large uncertainties in current CMM estimates. Here, we assimilated atmospheric methane column concentrations observed by the TROPOMI space borne instrument in a high-resolution regional inversion to estimate CMM emissions in Shanxi, a province representing 15% of the global coal production. The emissions are estimated to be 8.5± 0.6 and 8.6± 0.6 Tg CH4 yr-1 in 2019 and 2020, respectively, close to upper bound of current bottom-up estimates. Data from more than a thousand of individual mines indicate that our estimated emission factors increase significantly with coal mining depth at prefecture level, suggesting that ongoing deeper mining will increase CMM emission intensity. Our results show robustness of estimating CMM emissions utilizing TROPOMI images and highlight potential of monitoring methane leakages and emissions from satellites.

Developing basin-specific emission factors for accurate methane inventory and emission reduction strategies in Zonguldak Coal Basin, Turkey: Implications for enhancing safety and sustainability

This study develops basin-specific emission factors using historical coal production and methane emissions data to enhance methane inventories and emission reduction strategies in Turkey's Zonguldak Coal Basin. The basin is known for high levels of coal mine methane (CMM) emissions, posing a serious safety hazard to miners and affecting mine productivity. However, limited data on in-situ parameters related to Coal Mine Methane (CMM) emissions have been available. The study analyzes historical trends in CMM emissions (1980–2020) from the basin's underground coal mines, revealing declining emissions alongside coal production. Over this period, approximately 2.28 billion cubic meters of CMM were released. Continued historical coal production rates suggest a significant 6.63 MWe power generation potential. The investigation into coal production, average mining depth, and coal seam gas content reveal that CMM emissions primarily depend on coal production and mining depth. Utilizing available methane mitigation technologies could prevent an estimated 55.7 million tons of methane annually (equivalent to around 692,000 tons of CO2e). Importantly, the study calculates basin-specific emission factors (ranging from 7.24 m3/t to 21.66 m3/t) based on historical measurements, providing a more accurate regional representation than the Intergovernmental Panel on Climate Change (IPCC) default values. These factors are vital for identifying high-emission areas and guiding emission reduction strategy development. This study addresses a critical data gap in Turkey's estimation of methane emissions from underground coal mining, particularly in the Zonguldak coal basin. It establishes a foundation for future research on methane emissions from coal mines at various scales, contributing to improved understanding, emissions mitigation, safety enhancement, and sustainable coal mining practices.

Unintended mitigation benefits of China's coal de-capacity policies on methane emissions

Coal de-capacity policies are often used to promote the integration of coal resources and optimize the production structure in China. This study used a bottom-up approach to evaluate the unintended effect of China's coal de-capacity policies on methane emissions mitigation from 2011 to 2019. Under the effect of such policies, the closed coal capacity was 46% of the total coal capacity in 2011. A total of 9567 coal mines with 1610 Mt of capacity were closed. The capacity of low CH4-content coal mines accounted for 77% in 2019, and the capacity of high and outburst CH4-content coal mines decreased by 9% compared to 2011. The adjustment in coal production structure in turn affects coal mine methane emission intensity, hence the national average coal mine emission factor decreased from 9 m3/t in 2011 to 8 m3/t in 2019. The coal de-capacity policies generated a cumulative 10.70 Tg of methane emissions mitigation from 2011 to 2019, even with rebounded coal production. As the number of coal mine closures continues to increase, the priority phase-out of high and outburst CH4-content mines will further lead to greater methane mitigation. In the future, more attention should be paid to methane emissions from abandoned mines.

Strategies for heat recovery in a reverse flow reactor designed to lessen coal mine methane emissions test

ABSTRACT Thermal pollution resulting from the release of ventilation air methane (VAM) has emerged as a pressing concern in coal mining. This study aims to address this issue by harnessing the waste VAM energy and converting it into reusable resources, employing an efficient thermal flow reversal reactor. The research investigates five distinct heat extraction strategies and compares their performance. The numerical analysis focuses on transient heat recovery performance by employing a two-step reaction mechanism. Furthermore, the study uncovers the heat transfer characteristics of heat exchange tubes and conducts an analysis of construction costs and profit periods for the different strategies. The findings indicate that the central heat recovery strategy exhibits inferior recovery performance, resulting in higher outlet temperatures and lower extracted power. Conversely, the end recovery strategy successfully reduces heat loss by 56%. The two-sided strategy demonstrates better recovery performance, maintaining an average outlet temperature of 311 K. Additionally, the heat recovery efficiency of the heat exchange tube is approximately 85.6%. Although the combination strategy appears to reduce outlet heat loss, it results in an extended investment payback period.

Configurational Path of Decarbonisation Based on Coal Mine Methane (CMM): An Econometric Model for the Polish Mining Industry

This study presents the econometric model for the Polish mining industry on the topic of the configuration path of decarbonisation based on coal mine methane (CMM). CMM is released from coal mines around the world, including Poland. CMM is taken into account in the decarbonisation of countries with the highest underground coal production. Over the past ten years, CMM emissions have been gaining greater attention due to their status as We accept greenhouse gas (GHG) and their potential use as a clean energy resource. The very important problem for the mining plants is the system of controlling the level of methane. In this paper, we present an econometric model for mine production linear programming, taking into account both market considerations and controlling the amount of methane released into the air from mines. This model can use to control methane in the Polish mining industry. Moreover, this model can be used in the strategy of decarbonisation of the Polish industry according to the European strategy toward net zero (2050).

Characteristics of the methanotroph used in coalbed methane emission reduction: Methane oxidation efficiency and coal wettability

In the process of coal mining, a large amount of methane is emitted into the atmosphere every year, which enhances the greenhouse effect of the atmosphere. Microbial methane oxidation technology provides a new idea for methane emission reduction and methane control in coal mines. To improve the environmental adaptability of microorganisms, mixed methanotrophic consortia were selected from the natural environment. During the growth process, microorganisms grew most vigorously in the 4th–10th days and peaked on the 7th day. Affected by microbial metabolism, the pH (potential of hydrogen) of the solution increased, and the ORP (oxidation–reduction potential) decreased, both of which were negatively correlated. The selected mixed methanotrophic consortia have extremely strong methane-oxidizing ability, the volume of methane gas decreased by 71.19 %. It is particularly important that the microorganisms still have a certain methane oxidation capacity, after which the oxygen in the device is exhausted. The results showed that the mixed methanotrophic consortia adjusted the population structure to adapt to the changes in the surrounding environment and continued to exert methane oxidation ability. The contact angle between the bacterial solution and coal sample surface was far lower than that of pure water and culture medium. Microorganisms adsorbed onto the surface of the coal sample through self-movement, greatly improving the contact ability between the bacterial solution and the coal sample. The retention of microorganisms in the coal sample was affected by the flow velocity and the particle size of the coal sample. A low flow velocity and large contact area can improve the contact efficiency of microorganisms on the coal surface. Mixed methanotrophic consortia have high application value and feasibility in coal mine methane emission reduction and underground methane treatment.

Factors influencing the temporal variability of atmospheric methane emissions from Upper Silesia coal mines: a case study from the CoMet mission

Abstract. Methane is a powerful greenhouse gas responsible for around 20 % of radiative forcing (relative to the pre-industrial era) caused by all long-lived greenhouse gases (WMO, 2021). About 60 % of the global emissions are from anthropogenic sources, and coal mining is one of the largest contributors. Emissions are either estimated by bottom-up approaches (based on inventories) or top-down approaches (based on atmospheric measurements). Combining those with an accurate error estimation allows us to better characterise model errors e.g. caused by transport mechanisms. Here we provide a detailed description of factors influencing the coal mine methane emission variability. We use high-frequency (up to hourly) temporal data from seven coal mines in the Upper Silesian Coal Basin during the Carbon dioxide and Methane (CoMet 1.0) mission from 14 May to 13 June 2018. Knowledge of these factors for the individual ventilation shaft is essential for linking the observations achieved during the CoMet 1.0 mission with models, as most publicly available data in the bottom-up worldwide inventories provide annual emissions only. The methane concentrations in examined shafts ranged from 0.10 % to 0.55 %±0.1 % during the study period. Due to the changing scope of mining works performed underground, they were subjected to a significant variation on a day-to-day basis. The yearly methane average emission rate calculated based on 1 month's set of temporal data of the analysed subset of mines was of the order of 142.68 kt yr−1 (σ=18.63 kt yr−1), an estimate 27 % lower than the officially published State Mining Authority (WUG) data and 36 % lower than reported to the European Pollutant Release and Transfer Register (E-PRTR). We also found that emissions from individual coal mine facilities were over- and underestimated by between 4 % to 60 %, compared to the E-PRTR, when short-term records were analysed. We show that the observed discrepancies between annual emissions based on temporal data and public inventories result from (1) the incorrect assumption that the methane emissions are time-invariant, (2) the methodology of measurements, and lastly, (3) the frequency and timing of measurements. From the emission monitoring perspective, we recommend using a standardised emission measurement system for all coal mines, similar to the Methane Fire Teletransmission Monitoring System (SMP-NT/A). Legal safety requirements require all coal mines to implement this system. After an adaptation, the system could allow for gas flow quantification, necessary for accurate and precise estimations of methane emissions at a high temporal resolution. Using this system will also reduce the emission uncertainty due to factors like frequency and timing of measurements. In addition, it would be beneficial to separately identify the emissions from individual ventilation shafts and methane drainage stations. That would bridge the gap between bottom-up and top-down approaches for coal mine emissions. The intermittent releases of unutilised methane from the drainage stations are currently not considered when constructing regional methane budgets.

Managing Methane Emissions in Abandoned Coal Mines: Comparison of Different Recovery Technologies by Integrating Techno-Economic Analysis and Life-Cycle Assessment.

Methane emissions from worldwide increasing abandoned coal mines have posed multiple challenges of global warming, energy waste, and explosion risk. This study first profiles the dynamic patterns of coal mine methane emissions in different recovery technologies, methane extraction with drainage (MEWD, mine-water concurrently extracted and treated) and direct methane extraction (DME, noncontrol on mine-water), in two abandoned mines from Ningxia and Inner Mongolia as China's leading coal provinces. Then, we conducted a techno-economic analysis and life-cycle assessment to quantify their comprehensive benefits. The key findings are as follows: (1) MEWD can long recover methane, although the economic profits decrease with declining methane extraction volume. DME can only work for ∼5 years, after which the mine is flooded, where methane is sealed underground and not recoverable. (2) MEWD drains and further treats the mine-water with an additional 29.4-35.9 million CNY cost compared with DME, while MEWD can achieve greater life-cycle environmental benefits with more cumulative methane recovery, whose CO2-eq (GWP-100) and SO2 reductions are 64.4 and 53.4% higher than those of DME. (3) MEWD is more promising for large-scale implementation, where feed-in tariffs and carbon market measures can improve the economics for sustainable management of incremental abandoned mine methane.

A high-resolution gridded inventory of coal mine methane emissions for India and Australia

Coal mines are globally an important source of methane and also one of the largest point sources of methane. We present a high-resolution 0.1° × 0.1° bottom-up gridded emission inventory for methane emissions from coal mines in India and Australia, which are among the top 5 coal producing countries in 2018. The aim is to reduce the uncertainty in local coal mine methane emissions and to improve the spatial localization to support monitoring and mitigation of these emissions. For India, we improve the spatial allocation of the emissions (CH4 emissions: 825 [min: 166 – max: 1484] Gg yr−1) by identifying the exact location of surface and underground coal mines and we use a Tier-2 Intergovernmental Panel on Climate Change (IPCC) methodology to estimate the emissions from each coal mine using country-specific emission factors. For Australia (CH4 emissions: 972 [min: 863 – max: 1081] Gg yr−1), we estimate the emission for each coal mine by distributing the state-level reported total emissions using proxies of coal production and the coal basin-specific gas content profile of underground mines. Comparison of our total coal mine methane emission from India with existing global inventories showed our estimates are about a factor 3 lower, but well within range of the national Indian estimate reported to United Nations Framework Convention on Climate Change. For both the countries, the new spatial distribution of the emissions show large difference from the current global inventories. Our improved emissions dataset will be useful for air quality or climate modeling and while assessing the satellite methane observations.

Coal Mine Methane Emissions and Utilization Potential for the Zonguldak Coal Basin, Turkey

Coal Mine Methane Emissions and Utilization Potential for the Zonguldak Coal Basin, Turkey

Coal Mine Methane Emissions and Utilization Potential for the Zonguldak Coal Basin, Turkey

Coal Mine Methane Emissions and Utilization Potential for the Zonguldak Coal Basin, Turkey

Decreasing methane emissions from China’s coal mining with rebounded coal production

China is the world’s largest anthropogenic methane (CH4) emitter, with coal mine methane (CMM) as one of the main contributors. However, previous studies have not reach consensus on the magnitude and trend of China’s CMM emissions since 2010. Through distribution fitting and Monte Carlo methods, dynamic emission factors (EFs) of CMM at the province-level were derived with high confidence; along with the updated data on surface mining, abandoned coal mines, and methane utilization, we revealed that China’s annual CMM emissions were estimated at 20.11 Tg between 2010 and 2019 with a decline of 0.93 Tg yr−1. Although coal production was revived in 2017, we found that the growing trend of China’s CMM emissions since 2012 were curbed by the previously-overlooked factors including the growth of CMM utilization and coal production from surface mining, and decrease of EFs driven by the closure of high CH4-content coal mines and a regional production shift to lower-emission areas.

Sustained methane emissions from China after 2012 despite declining coal production and rice-cultivated area

China’s anthropogenic methane emissions are the largest of any country in the world. A recent study using atmospheric observations suggested that recent policies aimed at reducing emissions of methane due to coal production in China after 2010 had been largely ineffective. Here, based on a longer observational record and an updated modelling approach, we find a statistically significant positive linear trend (0.36 ± 0.04 () Tg CH4 yr−2) in China’s methane emissions for 2010–2017. This trend was slowing down at a statistically significant rate of -0.1 ± 0.04 Tg CH4 yr−3. We find that this decrease in growth rate can in part be attributed to a decline in China’s coal production. However, coal mine methane emissions have not declined as rapidly as production, implying that there may be substantial fugitive emissions from abandoned coal mines that have previously been overlooked. We also find that emissions over rice-growing and aquaculture-farming regions show a positive trend (0.13 ± 0.05 Tg CH4 yr−2 for 2010–2017) despite reports of shrinking rice paddy areas, implying potentially significant emissions from new aquaculture activities, which are thought to be primarily located on converted rice paddies.

Estimating Upper Silesian coal mine methane emissions from airborne in situ observations and dispersion modeling

Abstract. Abundant mining and industrial activities located in the Upper Silesian Coal Basin (USCB) lead to large emissions of the potent greenhouse gas (GHG) methane (CH4). The strong localization of CH4 emitters (mostly confined to known coal mine ventilation shafts) and the large emissions of 448 and 720 kt CH4 yr−1 reported in the European Pollutant Release and Transfer Register (E-PRTR 2017) and the Emissions Database for Global Atmospheric Research (EDGAR v4.3.2), respectively, make the USCB a prime research target for validating and improving CH4 flux estimation techniques. High-precision observations of this GHG were made downwind of local (e.g., single facilities) to regional-scale (e.g., agglomerations) sources in the context of the CoMet 1.0 campaign in early summer 2018. A quantum cascade–interband cascade laser (QCL–ICL)-based spectrometer adapted for airborne research was deployed aboard the German Aerospace Center (DLR) Cessna 208B to sample the planetary boundary layer (PBL) in situ. Regional CH4 emission estimates for the USCB are derived using a model approach including assimilated wind soundings from three ground-based Doppler lidars. Although retrieving estimates for individual emitters is difficult using only single flights due to sparse data availability, the combination of two flights allows for exploiting different meteorological conditions (analogous to a sparse tomography algorithm) to establish confidence on facility-level estimates. Emission rates from individual sources not only are needed for unambiguous comparisons between bottom-up and top-down inventories but also become indispensable if (independently verifiable) sanctions are to be imposed on individual companies emitting GHGs. An uncertainty analysis is presented for both the regional-scale and facility-level emission estimates. We find instantaneous coal mine emission estimates of 451/423 ± 77/79 kt CH4 yr−1 for the morning/afternoon flight of 6 June 2018. The derived fuel-exploitation emission rates coincide (±6 %) with annual-average inventorial data from E-PRTR 2017 although they are distinctly lower (−28 %/−32 %) than values reported in EDGAR v4.3.2. Discrepancies in available emission inventories could potentially be narrowed down with sufficient observations using the method described herein to bridge the gap between instantaneous emission estimates and yearly averaged inventories.

Site Trials and Demonstration of a Novel Pilot Ventilation Air Methane Mitigator

Ventilation air methane (VAM) mitigation has been challenging to the coal mining industry because (1) VAM represents the largest proportion of coal mine methane emissions, (2) its air volume flow r...

CMM emission laws and the sub-source drainage methods in coal mining: a case study in Yuwu coal mine, Northeastern Qinshui basin, China

ABSTRACT With the expansion of the coal mining depth and scales, the content of coal mine methane (CMM) is increasing, bringing the great challenge to the safe coal mining and greenhouse gas control. Researching CMM emission laws and its drainage technologies in underground coal mining is essential. This paper analyzed the sources of CMM emission in the workface and then put forward the grid method to measure the CMM emission laws in the single coal seam, which error was verified by the integral method. The CMM emission laws of the S2107 workface of the Yuwu mine, northeastern Qinshui basin, China were researched as a case study and it is found that the upper corner was the key position of CMM control in the workface. The sub-source CMM drainage methods by the strike high-level roadway and long vertical buried pipes were applied against the different CMM sources in the S2107 workface. The gas concentration in the return air was less than 0.6% during the CMM drainage, verifying the effectiveness of the sub-source CMM drainage methods.