Estimating greenhouse gas emissions from open-cut coal mining: application to the Sydney Basin

Quantification and Characterisation of Particulates from Australian Coal Mines: Towards Improved Emissions Estimation

A Tier 3 method to estimate fugitive gas emissions from surface coal mining

In recent years, credible atmospheric observations of methane emissions suggest that annual methane emission estimates in inventories for some Australian coal mining regions or facilities may be underestimated. A lack of well-constrained, mine-scale studies for open-cut (pit) coal mines continues to hinder discussions on emission estimates and the refinement of estimation methods for Australian open-cut coal mining facilities. Here, we present preliminary results from aircraft- and ground-based atmospheric measurements recorded in November 2024 in the Hunter Coalfield, NSW, Australia.Australia employs higher-Tier IPCC methodologies – Tier 2 (basin-specific) and Tier 3 (mine-specific, Methods 2 and 3 ) – under its National Greenhouse and Energy Reporting (NGER) Scheme to estimate open-cut coal mine emissions. These methods rely on the use of coal core gas content to estimate methane emissions from open-cut mine complexes. However, Methods 2 and 3 have never been validated using airborne or ground-based time series observations.While coarse-resolution satellites like TROPOMI can quantify coal mine emissions at regional scales (Sadavarte et al., 2021; Palmer et al., 2021), their limited spatial resolution reduces their effectiveness for verifying annual inventory reported emissions at the scale of individual mines. Additionally, the ability of point-source imaging satellites to quantify emissions from individual open-cut coal mines remains uncertain. Coal seam blasting prior to extraction can be considered a point source; however, open-cut coal mines have various continuous diffuse methane sources that also need to be quantified. The diffuse sources include, among others, emissions from beneath the pit floor, lateral diffusion along coal seams and other rock strata in the mine walls, rock waste piles, and areas of in situ biological production, such as water management ponds. Aircraft- and ground-based technologies have the potential to measure both point and diffuse sources of methane, thus providing a potential pathway for verifying greenhouse gas inventories determined using approved IPCC methodologies.During this measurement campaign in the Hunter Coalfield, a research aircraft flew instruments to collect in-situ atmospheric measurements of methane and carbon dioxide mole fractions, along with GPS and meteorological data. These data were used to make rate of methane emission estimates downwind of individual coal mine complexes. Aerosol size and particle number concentration measurements and high-resolution airborne  LiDAR imagery were also acquired to aid in source attribution. These measurements were complemented by ground-based EM27/SUN solar absorption spectrometer instruments positioned upwind and downwind of the same coal mining complexes. Comparisons between emissions derived from the aircraft-base, ground station EM27/SUN observations, and operator-reported coal mine methane emissions will be presented.Palmer, P. I., Feng, L., Lunt, M. F., Parker, R. J., Bösch, H., Lan, X., Lorente, A., and Borsdorff, T.: The added value of satellite observations of methane for understanding the contemporary methane budget, Phil. Trans. R. Soc. A., 379, 20210106, https://doi.org/10.1098/rsta.2021.0106, 2021.Sadavarte, P., Pandey, S., Maasakkers, J. D., Lorente, A., Borsdorff, T., van der Gon, H. D., Houweling, S., and Aben, I.: Methane emissions from superemitting coal mines in Australia quantified using TROPOMI satellite observations, Environmental Science & Technology, 55, 16573–16580, https://doi.org/10.1021/acs.est.1c03976, 2021.

Diversity in reservoir surface morphology and climate limits ability to compare and upscale estimates of greenhouse gas emissions

Particulate emission rates for open surfaces in Australian open cut black coal mines

Rank-order concordance among conflicting emissions estimates for informing flight choice

Open cut black coal mining: Empirical verification of PM2.5 air emission estimation techniques

Porvair makes environmental improvements across its global operations

There are three opencast Coal Mine pits in the area, namely Pandharkawda OC, Marki OC, and Mini Marki OC. The Opencast Pit at Marki has an area of 44 ha and will attain a maximum depth of 50 mbgl with open pit mine life of 10 years. Pandharkawda Opencast is having an area of 40 ha with maximum depth of 45 mbgl having opencast mine life of 9 years. Mini Marki OC is the third small Opencast Pit which will start production in 28th Year i.e., after the closure of Pandharkawda Underground. It has a small area of 7.25 ha with life span of 3 Year (28th to 30th Year). Thus, the total opencast mining area is 91.25 ha. In the area, two underground (UG) patches are proposed namely Marki and Pandharkawda UG which will commence production after completion of opencast workings. These sections will attain a maximum depth of 150 mbgl. Life span of Marki UG will be 20 Years (10th to 27th Year) and that of Pandharkawda UG will be 18 Years (9th to 27th Year). Coal Mine is producing coal @ 0.30MTPA peak since 2017. The Coal Mine was operated for 3 years from 2011 to 2013 and again resumed production since 2017. Hence, the opencast mine Pandharkawda OC, Marki OC will last its operation till first 9 years, and underground Coal Mine will continue from 9th year onwards till 27th year. Total planned mine life of Marki Mangli-I Coal Mine is around 20 years whereas Mini Marki OC will start its operation from 27th years onwards till 30th year. Study for prediction of groundwater withdrawal for subjected Coal Mine was carried out pre-monsoon and post-monsoon period in year 2016 to quantify the groundwater withdrawal from coal mining operations. The predicted quantity of groundwater withdrawal from Coal Mine is used by mine management to create groundwater recharge structure to compensate the groundwater discharge during mine operations.

Highwall mining is a method that involves using a continuous highwall miner system (CHM) to extract coal from the remaining coal seams, which has proven to be an effective and safe method for extracting coal after open-pit mining. However, application cases globally have shown that the feasibility of highwall mining in open-pit coal mines is subject to geological conditions, mining techniques, and other factors. If application conditions are not suitable, equipment may be trapped under collapsed coal–rock masses and unable to be retrieved, resulting in severe safety issues for slope stability. To meet the real-world demand for extracting the remaining coal in open-pit coal mines in China, it is urgent to conduct a feasibility evaluation of highwall mining in these areas. This paper establishes a mathematical evaluation framework for assessing the feasibility of highwall mining by summarizing a large number of engineering application cases globally and analyzing various technical characteristics such as geological deposit conditions, mining techniques, and technical equipment. The analytic hierarchy process (AHP), fuzzy comprehensive evaluation (FCE) and variable weight theory (VWT) are utilized in conjunction to form this framework, which includes four secondary indicators: geological deposit factors, mining technique factors, safety impact factors, and economic evaluation factors, and 20 tertiary sub-indicators, along with their corresponding characteristic values. The feasibility sub-set is divided into four categories: infeasible, basically feasible, relatively feasible, and highly feasible, and the values of the sub-indicators strictly follow and represent these four levels of feasibility. Weight vectors for the sub-indicators are obtained through a judgment matrix established within the mathematical evaluation framework. The fuzzy relationship matrix of the sub-indicators is constructed using fuzzy mathematical membership functions, and the final feasibility evaluation is determined through two-level comprehensive evaluation. The accuracy of the model is verified using the characteristic parameters of open-pit coal mines under two different conditions (JZT coal mine in Inner Mongolia, China, and GC coal mine in Australia). The results demonstrate that the maximum evaluation membership degree for the JZT mine is 0.7113, belonging to the “highly feasible” level, while the GC mine is 0.3304, belonging to the “basically feasible” level, which aligns well with real-world usage, proving that the evaluation model can effectively reveal the performance and membership degree of each indicator in different application cases. By quantitatively characterizing the feasibility level of highwall mining technology under different application conditions, this evaluation model can provide scientific guidance for coal mining enterprises to introduce CHM for highwall mining operation in open-pit coal mines.

Abstract. Conferences, meetings and congresses are an important part of today's economic and scientific world. But the environmental impact, especially from greenhouse gas emissions associated with travel, can be extensive. Anthropogenic greenhouse gas (GHG) emissions account for the warming of the atmosphere and oceans. This study draws on the need to quantify and reduce greenhouse gas emissions associated with travel activities and aims to give suggestions for organizers and participants on possible ways to reduce greenhouse gas emissions, demonstrated on the example of the European Geography Association (EGEA) Annual Congress 2013 in Wasilkow, Poland. The lack of a comprehensive methodology for the estimation of greenhouse gas emissions from travel led to an outline of a methodology that uses geographic information systems (GIS) to calculate travel distances. The calculation of travel distances in GIS is adapted from actual transportation infrastructure, derived from the open-source platform OpenStreetMap. The methodology also aims to assess the possibilities to reduce GHG emissions by choosing different means of transportation and a more central conference location. The results of the participants of the EGEA congress, who shared their travel data for this study, show that the total travel distance adds up to 238 000 km, with average travel distance of 2429 km per participant. The travel activities of the participants in the study result in total GHG emissions of 39 300 kg CO2-eq including both outward and return trip. On average a participant caused GHG emissions of 401 kg CO2-eq. In addition, the analysis of the travel data showed differences in travel behaviour depending on the distance between conference site and point of origin. The findings on travel behaviour have then been used to give an estimation of total greenhouse gas emissions from travel for all participants of the conference, which result in a total amount of 79 711 kg CO2-eq. The potential for reducing greenhouse gas emissions by substituting short flights with train rides and car rides with bus and train rides is limited. Only 6 % of greenhouse gas emissions could be saved by applying these measures. Further considerable savings could only be made by substituting longer flights (32.6 %) or choosing a more central conference location (26.3 %).

ABSTRACTThere are a significant number of uncontrolled coal mine fires (primarily due to spontaneous combustion of coal), which are currently burning all over the world. These spontaneous combustion sources emit greenhouse gases (GHGs). A critical review reveals that there are no standard measurement methods to estimate GHG emissions from mine fire/spontaneous combustion areas. The objective of this research paper was to estimate GHGs emissions from spontaneous combustion of coals in the Indian context. A sampling chamber (SC) method was successfully used to assess emissions at two locations of the Enna Opencast Project (OCP), Jharia Coalfield (JCF), for 3 months. The study reveals that measured cumulative average emission rate for CO2 varies from 75.02 to 286.03 gs−1m−1 and CH4 varies from 41.49 to 40.34 gs−1m−1 for low- and medium-temperature zones. The total GHG emissions predicted from this single fire affecting mines of JCF vary from 16.86 to 20.19 Mtyr−1.

The main types of accidents in 6–10 kV power supply systems of mining enterprises are considered, such as short circuits, single-phase earth faults, phase failures, with their percentage relationships established. Mining enterprises are divided into three groups: open-cut mining enterprises (quarries and open coal pits); enterprises for extraction of minerals by underground method (underground coal and ore mines); mining & processing enterprises (concentrating factories, alumina plants, fertilizer production enterprises). The analysis of the accident rate of power supply systems of mining enterprises carried out for the period from 1995 to 2015 makes it possible to trace the dynamics of the above types of accidents and determine their most common form — single-phase earth fault. Over the above period, in the 6 – 10 kV power supply systems of quarries and open coal pits, underground coal and ore mines, and mining & processing enterprises, the share of single-phase earth faults was found to be within the following ranges: 65 – 76%; 60 – 69%; 58 – 67%, respectively. The greatest increase in accidents during the period under review was observed in 6 –10 kV power supply systems of quarries and open coal pits; with the total accident rate having risen with a factor of 3.21 from 1995 to 2015. The accident rate growth factor for underground coal and ore mines, and mining & processing enterprises amounted to 2.06 and 2.72, respectively. The changes are shown in specifi c types of accidents and general accident rate in the systems of electricity supply to quarries and open pits, underground coal and ore mines, and mining & processing enterprises. It is established that in the 6 – 10 kV power supply systems of the above-mentioned mining enterprises, the changes in single-phase earth faults and general accident rate are described by linear equations. On the basis of established patterns, a forecast is made of the change in the accident rates in power supply systems of the mining enterprises under consideration up to the years 2020 ÷ 2025.

According to statistical reports of coal enterprises for 2015–2019 43 open-pit mines are working in the methane zone. At the same time, it can be stated that enterprises are not developing measures to reduce greenhouse gas emissions. This is largely due to the lack of a model for methane emission into the working area of the mine. The main sources of methane emissions from open-pit mines and the factors influencing them have not been identified. The purpose of the study is to determine the main sources of methane emissions during open-pit coal mining and the main characteristics on which gas emission depends. In this regard, the paper presents the results of modeling methane emissions during open-pit coal mining and solving the analytical problem of methane emissions. The analysis was carried out for three sources of methane emissions: when drilling wells; from exposure of a carbon rock massif; and during coal transportation. Based on the results of the study, the main sources of methane emissions into the atmosphere from open-pit coal mining were considered. It was also taken into account that methane can be emitted from both coal seams and host rocks. An averaged cross section was analyzed, leading in the methane zone. Gas emission patterns depending on the permeability value, geometric parameters of the section field, drilling and blasting wells, coal particle sizes and other parameters were identified. It was determined that the values of gas emission can affect the concentration of methane in the atmosphere of the section, as well as the fire safety of surface mining operations. Studies on determining the possibility of exceeding the maximum permissible concentration of methane in the atmosphere of the cut and the possibility of its ignition have been updated.

One of the most difficult challenges facing the coal mining industry is rehabilitation of open cut mines in the absence of sufficient quality and quantity of topsoil. As a result, the growth medium for rehabilitation of open cut mines is often mine spoil that has poor chemical and structural properties. Microorganisms play a critical role in natural soil forming processes, nutrient cycling and soil aggregate stabilisation. However, soil microbiota and their impact on soil chemistry and structure has traditionally been overlooked in mine site remediation and mine spoil amelioration. Soil bioengineering, using microbial inoculants to modify soil chemistry and structure, is a novel approach that has the potential to positively alter the chemical and physical limitations prevented by mine spoil and improve mine site rehabilitation outcomes. This review focuses on the importance of microbiology in the spoil-to-soil transformation after open cut coal mining and discusses the ways that microbial inoculants could be used to accelerate the amelioration of coal mine spoil during rehabilitation. The work seeks to establish a platform for soil bioengineering approaches to be considered during rehabilitation of open cut coal mines. The review focuses on Australian open cut coal mines but has application for all mines with nutrient limited substrates and/or saline or sodic spoil that is prone to erosion.