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Currently, there is an increasing number of research studies on underground storage of hydrogen in porous rocks (aquifers and depleted hydrocarbon fields). An important aspect of this process is the efficiency of hydrogen storage, which is defined as the correct operation of a storage facility (the ability to inject and withdraw an appropriate quantity of gas) and the safety of storage, which is influenced by numerous factors, including geological factors. With an increasing number of publications, gathering knowledge and keeping track of scientific progress is becoming increasingly complex. In addition to the technical interdependence of the parameters analysed, there are also interrelationships between scientific publications addressing issues related to underground hydrogen storage in porous rocks. The aim of this paper is to analyse the literature on hydrogen storage efficiency in porous rocks and, on the basis of the analysis, to identify the most important research trends and issues relevant to their implementation. This article presents an analysis of publications indexed in the SCOPUS database. The analysis included publications that contained expressions related to the relevant search phrases in their title, abstract or keywords. The dynamics of changes in the interest of researchers on the problem of hydrogen storage in porous rocks and the distribution of studies by geographical location (countries) are presented. Based on an analysis of the number of citations, the most influential publications were identified. Using the VOSviewer version 1.6.19 software, clusters reflecting research sub-areas were identified based on co-occurrence analysis, such as geological and reservoir aspects, reservoir engineering aspects, hydrogeological aspects and petrophysical aspects. Bibliometric methods have great potential for performing quantitative confirmation of subjectively delineated research fields and/or examining unexplored areas. The literature on underground hydrogen storage in porous rocks has been growing rapidly since at least 2018, with researchers conducting their studies in four major research streams: geological and reservoir aspects, reservoir engineering aspects, hydrogeological aspects and petrophysical aspects. [ABSTRACT FROM AUTHOR]

The subject of the study was the No. 116/2 coal seam belonging to the Cracow Sandstone Series of the Upper Silesian Coal Basin. Reflectograms of the samples taking into account all the vitrinite group macerals present in the coal were recorded for ΔR° close to the standard deviation and in the standard range. A careful analysis of vitrinite reflectograms reveals the presence of three or four clearly distinguished peaks. When assessing the rank of coal, only the main maximum, peak No. 4, was considered to be significant. Measurements of the average reflectance of collotelinite were made only on the vitrinite surfaces with a thickness of more than 1 mm. Only two maxima were revealed on detailed reflectograms. These maxima correlate with the peaks marked as No. 3 and 4 in the sample reflectograms taking into account all the vitrinite group macerals. The Cdaf content in the tested coal from the Janina coal mine is between 75.9 and 77.5 wt%, while for vitrain, it ranges from 71.1 to 75.5 wt%. This relationship is an exponential regression with a correlation coefficient of r = 0.95h and can be approximated by a linear correlation of r = 0.94. The correlation strength between the volatile matter content and the coefficient of average reflectance in the vitrinite of the tested coal was also examined. The statistically significant correlation is strong, which is expressed by the exponential correlation coefficient "r" being close to 0.99 and its linear approximation with the correlation coefficient r = 0.98. However, no correlation was found between the measured reflectance values and the GI coefficient calculated for the examined samples. [ABSTRACT FROM AUTHOR]

The concentration of critical elements, including such REE as Fe, Co, W, Zn, Cr, Ni, V, Mn, Ti, Ag, Ga, Ta, Sr, Li, and Cu, in the so-called fly ash obtained from the 9 Polish power plants and 1 thermal power station has been determined. The obtained values, compared with the global average concentration in bituminous coal ash and sedimentary rocks (Clarke values), have shown that the enrichment of fly ash in the specified elements takes place in only a few bituminous coal processing sites in Poland. The enrichment factor (EF) is only slightly higher (the same order of magnitude) than the Clarke values. The enrichment factor in relation to the Clarke value in the Earth’s crust reached values above 10 in all of the examined ashes for the following elements: Cr, Ni, V, W, and, in some ash samples, also Cu and Zn. The obtained values are low, only slightly higher than the global average concentrations in sedimentary rocks and bituminous coal ashes. The ferromagnetic grains (microspheres) found in bituminous coal fly ashes seem to be the most economically prospective in recovery of selected critical elements. The microanalysis has shown that iron cenospheres and plerospheres in fly ash contain, in addition to enamel and iron oxides (magnetite and hematite), iron spinels enriched in Co, Cr, Cu, Mn, Ni, W, and Zn.

The earliest studies of the Moon consisted of observations from Earth and meteorites containing lunar material. As technology progressed, the observations were made using remote sensing techniques. The next stage of the Moon reconnaissance consisted of unmanned flights, and later manned flights, with the help of which, in-situ tests were performed. The obtained materials enable the formulation of conclusions both about the geological structure and the mineral resources of the moon. The latest maps provided by the United States Geological Survey (USGS) and NASA Planetary Data System (PDS) enable a detailed analysis of the geological structure of the moon. Since they are available in shapefile format for QGIS and ArcGIS software, they can be freely modified and processed. On the basis of these, it is possible to analyze the complexity of the geological structure of the moon, especially with regard to the structure of its substrate and the surface covered with craters. Data obtained from the observation of the Moon with the use of research satellites and research carried out during landings related to the collection of samples enabled the formulation of conclusions about the raw materials present there. These raw materials are related to the surface layer of the so-called regolith, the recognition of which is relatively good because it is based not only on remote studies but also on the basis of collected samples. Additionally, there are indications of the possible presence of mineral resources related to the substrate, but its recognition is relatively poor because it is based on remote and geophysical surveys. The presented analysis shows that the Moon has such minerals as rare earth elements (REE) and Th and U found in the KREEP area. Fe and Ti are found to be in basaltic lava flows occurring in the mares and aluminum, silicon and Helium-3 occur in the regolith. [ABSTRACT FROM AUTHOR]

The new boreholes drilled between 2009 and 2012 enabled a detailed exploration of the profile of the Kraków sandstone series in the Dąb area between the "Sobieski" and "Janina" mining plants, USCB (Upper Silesian Coal Basin). The core from the No. 111. bituminous coal seam was selected for further analysis. 30 intervals corresponding to the defined lithotypes were separated in tire seam with a thickness of 116.8 cm. The thickness of lithotypes ranges from 10 mm to 89 mm. A microprofile of the examined seam was made using the modified method of determining microlithotypes. A quantitative determination of the macérai composition was performed for each interval corresponding to the separated lithotypes. This allowed petrographic and facies characteristics of the seam to be determined. Its lower part is dominated by lithotypes with a large share of bright coal - vitrain coal. This section of the profile was formed under conditions of a strongly flooded wet forest swamp. In the upper section of the seam, a higher macroscopic share of dull coal - durain was observed. The microscopic analysis has shown that the conditions dominant during the formation of this section were typical for swamp forest peats. New technologies also require expanding knowledge about the structure of coal seams. This is only possible with a detailed profiling of the coal seam on a macro scale combined with micro-profiling and a detailed petrographic description of the isolated lithotypes. This methodology is also useful in tire facies analysis of bituminous coal seams. [ABSTRACT FROM AUTHOR]

The Bogdanka coal mine, the only currently operating mine in the Lublin Coal Basin (LCB), extracts coal from the Upper Carboniferous formations of the LCB. The average sulfur content in the No. 385/2 seam is 0.98%, while in the case of the No. 391 seam it is slightly higher and amounts to 1.15%. The iron sulfides (pyrite and marcasite) in bituminous coal seams form macroscopically visible massive, vein, and dispersed forms. A microscopic examination has confirmed their complex structure. Massive forms contain euhedral crystals and framboids. The sulfide aggregations are often associated with a halo of dispersed veins and framboids. Pyrite and marcasite often fill the fusinite cells. Framboids are highly variable when it comes to their size and the degree of compaction within the carbonaceous matter. Their large aggregations form polyframboids. The cracks are often filled with crystalline accumulations of iron sulfides (octaedric crystals). The Wavelenth Dispersive Spectrometry (WDS) microanalysis allowed the chemical composition of sulfides in coal samples from the examined depoists to be analyzed. It has been shown that they are dominated by iron sulfides FeS2 - pyrite and marcasite. The examined sulfides contain small admixtures of Pb, Hg, Zn, Cu, Ag, Sb, Co, Ni, As, and Cd. When it comes to the examined admixtures, the highest concentration of up to 0.24%, is observed for As. In addition, small amounts of galena, siderite, and barite have also been found in the examined coal samples. The amounts of the critical elements in the examined samples do not allow for their economically justified exploitation. Higher concentrations of these elements can be found in the ashes resulting from the combustion process. [ABSTRACT FROM AUTHOR]

Bituminous coal samples were collected from mine excavations of six mines in the Upper Silesian Coal Basin. In the mentioned mining excavations, the stratighaphic sections, in the form of spot samples, were measured. Based on the macroscopic and microscopic observation, an attempt was made to determine the different lithotypes of coal. Vitrain coal is made of tellinite and collotelinite; the thickness of the layers varies from very thin, thin, medium, to coarse. Durain, which is dominated by macerals from the vitrinite group, is characterized by a darker, almost black color, genetically linked to heavily flooded peat areas, where the deposited phytogenic material is subjected to humification and gelification processes. A brighter durain, with a dark gray color, is dominated by macerals from the inertinite group that originated in the shallower areas of peat bogs where the water level was periodically lowered, which has led to the oxidation of the material deposited in the peat bog. Fusain is another coal component or constituent; it is produced as a result of peat bog fires. It is a charred (not burned) material deposited in the form of layers, lenses, usually with a thickness of up to several millimeters (or, less commonly, several centimeters), or dispersed in the form of shreds in the durain. The petrographic composition is dominated by fusinite and inertodetrinite. Fusain occurs in two varieties: soft (empty cellular spaces) and hard, usually mineralized with carbonates (siderite) or sulphides (pyrite, marcasite). The structure of bituminous coal is, due to its origin, most often laminated and consists of alternating dull and bright layers. Occasionally, such layering can be observed in bright coal, which is the result of layering of large parts of gelified plant materials. When it comes to larger sections of dull coal (without bright coal) in the profile, a solid structure can be observed. Some of the sections in the coal seam profiles show a distorted structure; warped, sometimes shredded layers of vitrain in durain, often containing lenses or shreds of fusain, can be observed. [ABSTRACT FROM AUTHOR]

Due to dynamic climatic changes resulting, among others, from the use of coal, the content of harmful substances in coal is of particular importance. Dangerous air pollution resulting from the burning of coal (e.g. As, S e, Hg, Pb, S b) is often associated with sulfide minerals in coal. The study focused on the sulphides occurring in Polish hard coal deposits. S ulfides are one of the forms of occurrence of sulfur in coal. I n this paper, an emphasis has been placed on on the characteristics of forms of occurrence of sulphides on both macroscopic and microscopic scale and on the chemical analysis in the micro area. The study has been conducted for the No. 301-308 seams from the eastern part of the Upper S ilesian C oal Basin, stratigraphically belonging to the highest part of the Orzesze Beds s.s. (Westphalian B). The coal samples have been collected from the coal seams in the underground excavations of the following coal mines: Jan Kanty, S obieski Jaworzno III, Wesoła and Z iemowit hard coal mine. Iron sulfides (pyrite, marcasite) in coal seams of the Orzesze Beds s.s. form various forms of macroscopically visible aggregates. These include massive, vein, pocket-like (impregnation) or dispersed forms. On the basis of microscopic observations, the following forms of occurence of iron sulphides in the tested coal have been determined: skeletal and massive vein forms, massive pocket-like (impregnation) forms, framboidal pyrite and euhedral crystals. The most common form of sulfides in the studied coal seams are vein forms cutting across bedding, usually creating complex dendritic and skeletal forms. I ron sulfides often occur in pocket-like (impregnation) forms, not directly linked with vein forms and fusinite. The WDS analysis in the micro area has revealed the chemical composition of sulfides in eight coal samples. As follows from the analysis, the tested coal seams are dominated by FeS2 iron sulfides. I t has been shown that the iron sulfides contained small admixtures of Pb, Hg, Z n, Cu, Ag, C o S b and Ni. The admixtures of As and C d have been observed only in individual minerals. Lead, reaching up to 1.06%, has the highest concentration out of all admixtures in pyrite and marcasite. S mall amounts of galena, titanium oxides (rutile), monazite and barite have also been found in the tested coal samples. L ocally, vein forms, pyrite and dolomite were interlaying each other; the same applies to pyrite and apatite. I n addition, dolomite fills part of the cells in fusinite. [ABSTRACT FROM AUTHOR]