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The paper addresses the problem of geomechanical effects in the vicinity of production/injection wells and their impacts on the processes of enhanced oil recovery by CO2 injection and CO2 sequestration in a partially depleted oil reservoir. In particular, it focuses on natural fracture systems and their dynamics caused by variations in the rock geomechanical state due to reservoir pressure changes during production/injection processes. The comprehensive approach to the problem requires the combined modeling of both geomechanical and flow phenomena associated with effective coupling simulations of their evolution. The paper applies such an approach to a real, partially depleted oil reservoir in Poland. An effective method of coupled geomechanical and dynamic simulations was used together with the natural boundary and initial conditions for both simulation types. In addition, typical operating conditions were applied in analyzing the processes of enhanced oil recovery by CO2 injection and CO2 sequestration. The detailed results of relevant modeling and simulations are presented and discussed focusing on various scale consequences, including the reservoir, well, and completion ones. Both general conclusions as well as the ones specific to the analyzed geological structure are drawn; they confirm the significant dependence of well performance on geomechanical effects and point out several key factors for this dependence. The conclusions specific to the analyzed structure concern fracture reactivation in tensile/hybrid failure mode caused by pressure build-up during CO2 injection and the importance of the fracture-induced aperture changes resulting from the normal stress, while the shear stress is found to be negligible. [ABSTRACT FROM AUTHOR]

The role of interzonal airflows is especially pronounced in naturally ventilated buildings. In such buildings, reversed airflows in the ventilation stacks might occur as well. This affects the air exchange rate and contaminant distribution in buildings. A significant increase in carbon dioxide concentration is a characteristic phenomenon for poorly ventilated rooms. This paper demonstrates the application of metabolic carbon dioxide concentration measurements for interzonal airflow estimation in naturally ventilated buildings. The presented method is based on the continuous measurements of CO2 concentration at one point in each zone. These measurements are used to estimate airflow pattern in a multizone building by applying an inverse analysis. The developed methodology employs an iterative Levenberg-Marquardt procedure to maximise the nonlinear likelihood function. The validity of the method was verified against measurements carried out in a single naturally ventilated room. Further, the method was applied to calculate the airflow pattern in two apartments in Poland, containing 4 and 6 zones. The obtained results revealed very poor ventilation in both investigated apartments and reversed airflow in exhaust ducts. The amount of fresh air entering the rooms was insufficient to ensure good indoor air quality. The developed methodology can be effectively used as a diagnostic tool to identify the potential problems with ventilation systems. [ABSTRACT FROM AUTHOR]

The authors compare the energy consumption and CO2 emissions from vehicles using internal combustion engines (ICE), battery electric vehicles (BEV), fuel cell electric vehicles (FCEV), and two types of hybrid vehicles, BEV-ICE hybrid and BEV-FCEV hybrid. This paper considers several scenarios for four countries' electricity production from primary energy sources to estimate total CO2 release. Energy consumption of the vehicle per 100 km, emissions during manufacturing, battery production, and lifecycle of the vehicle are considered in the total amount evaluation of CO2 released. The results show that with current technologies for battery manufacturing, and a significant proportion of national grid electricity delivered by fossil fuels, BEV is the best choice to reduce carbon emissions for shorter driving ranges. In the case of electricity generation mainly by low-carbon sources, FCEV and BEV-FCEV hybrid vehicles end up with lower carbon dioxide emissions. In contrast, with electricity mainly generated from fossil fuels, electric vehicles do not reduce CO2 emissions compared to combustion cars. [ABSTRACT FROM AUTHOR]

Abstract The objective of this paper is to evaluate the possible migration of coal-bed methane and carbon dioxide to the earth's surface in a selected areas from the southern part of the Upper Silesian Coal Basin (USCB) and resulted hazards produced by near-surface gas migration, referred to the geological setting and the origin of these gases. The surface geochemical survey was run over the areas of both the operating and the abandoned bituminous coal mines, including the remediated shafts and the regional tectonic dislocations: the Bzie-Czechowice and the Jawiszowice fault zones. The survey included a total of 453 soil gas samples collected at a depth of about 1.2 m and along 7 horizontal profiles as well as in the vicinities of remediated shafts. All collected gas samples were chromatographically analysed for methane and carbon dioxide concentrations. Selected samples showing increased concentrations of methane and/or carbon dioxide were analysed also for stable carbon isotopes of these gases. Additionally, gas emission was measured at 5 sites selected due to the increased concentrations of the gases. The maximum detected concentrations of methane and carbon dioxide in soil gas samples were 52.8 and 17.4 vol%, respectively. The closure of high methane-emitting bituminous coal mines in the USCB, including the termination of mine ventilation, caused the increase of average methane concentrations in the near-surface zone. Vast anomalies of both gases can be the effects of migration from secondary accumulations of "free" methane present in the elevated parts of Carboniferous formation capped by Miocene claystones and mudstones. Methane originated from primary accumulations located beneath the degassing zone and migrated along fault zones. However, carbon dioxide migrated from both the primary and the secondary accumulations, and, sometimes, it originated also from secondary oxidation of methane. The methane recovery captured with degassing wells run in the area of the abandoned "Morcinek" Mine disturbed the naturaly, vertically migrating methane towards the earth's surface and caused the local decrease of average methane concentrations in soil gas collected along the D-D' sampling line. It was additionally confirmed by relatively high methane concentrations (over 50 vol%) detected in samples collected from the wells degassing the shafts I, II and III of the closed "Morcinek" Mine. The methane is of microbial origin and migrated from secondary accumulation located within the Carboniferous (Pennsylvanian) coal-bearing strata. In the regional tectonic zone of the Bzie-Czechowice Fault, over 4 times higher average carbon dioxide concentrations were detected, in comparison with those analysed in the Jawiszowice Fault Zone. Carbon dioxide was of microbial origin, migrating from a secondary accumulation. Relatively low values of both the methane and carbon dioxide emissions were noticed at sampling sites, where elevated concentrations of both gases were encountered previously in the near-surface zone. This suggests that gases may accumulate in the near-surface zone as a result of long-term, and relatively slow migration from the depth. Hence, and in this case the potential gas hazard caused by uncontrolled and fast inflow of methane and carbon dioxide to a basements of buildings is insignificant. Highlights • The closure of coal mines caused the increase of methane concentrations in soil gas. • Methane recovery with wells disturb vertical migration of gases towards the surface. • Thermogenic and microbial CH 4 and CO 2 migrate from Pennsylvanian coal-bearing strata. • Low values of CH 4 and CO 2 emission shows insignificant gas hazard at the surface. [ABSTRACT FROM AUTHOR]

Our paper presents a simplified model of carbon dioxide concentrations in classrooms equipped with stack ventilation systems, based on experimental research. The test was conducted in six classrooms in the building of the Faculty of Civil and Environmental Engineering of Białystok University of Technology in northeastern Poland. The research included both classrooms that were not mechanically ventilated and classrooms that were ventilated by opening the windows during breaks between classes. In all classrooms, a linear increase in the concentration of carbon dioxide during the classes was observed. The increase of the concentration of carbon dioxide in spaces of this type depends mostly on the volume of and the number of persons present in the space. [ABSTRACT FROM AUTHOR]

The objective of this paper is to determine the reasons, origin and character of periodical changes of methane and carbon dioxide concentrations in the near-surface zone as well as emission of these gases to atmosphere after closing bituminous coal and anthracite mines in the former Wałbrzych Coal District (SW Poland). The measurements were performed during the period including the active impact of “water piston effect” on the migration of a coal-bearing gases as well as the period of stabilization of water table of the Pennsylvanian aquifer. In the years 1997–2005, 20 sampling sessions were completed during which 3210 soil gas samples were collected at a depth of about 1.2 m and along 4 measurement lines located in the Gorce and the Sobięcin depressions. Maximum methane and carbon dioxide concentrations measured in soil gas samples reached 32.4 and 15.7 vol%, respectively. Isotopic study shows that coal-bed gases, recent microbial methane, and multigenetic carbon dioxide from degassing of ground-waters of the Upper Pennsylvanian aquifer occur within the near-surface zone of the Wałbrzych Coal District. Within the Serpukhovian Wałbrzych and Upper Bashkirian-Moscovian Žacleř coal-bearing formations three genetic types of coal-bed gases occur: Variscan thermogenic (methane, higher gaseous hydrocarbons and carbon dioxide), endogenic (abiogenic) carbon dioxide and “late” (Late Cretaceous) and recent microbial methane and carbon dioxide. Changes of mean concentrations of methane and carbon dioxide in the near-surface zone recorded during years of studies demonstrated the influence of “water piston effect”, which drives migration of coalbed gases towards the earth surface. In both the Gorce and the Sobięcin depressions, gas migrates with various intensity. Generally, the lower methane emission measured in the years 2004–2005, and compared with the period 1999–2000, resulted from the stabilization of groundwater table whereas higher carbon dioxide emission confirms the degassing of shallow groundwaters. Anomalous concentrations of methane and carbon dioxide were related to numerous faults and fracture systems cutting the steeply dipping Upper Mississippian and Pennsylvanian coal-bearing formations, and to the outcrops of these rocks. However, in the near-surface zone, multiproportional mixing of coal-bed gases, recent microbial methane and carbon dioxide is observed. Periodical changes of stable carbon isotope composition of methane and carbon dioxide of near-surface zone in particular sessions are caused by the time-related change of location of water table of Pennsylvanian aquifer in the complicated structure of the Gorce and Sobięcin depressions. Persistently anomalous concentrations of methane and carbon dioxide in the near surface zone, still observed after several-years-long stabilization of groundwater table, seem to indicate a continuous supply of coalbed gases to the near-surface zone through pervious dislocations. Such an interpretation is confirmed by the extreme value of methane emission detected at a particular sampling site after the cessation of the “water piston” effect. It was presumably caused by the secondary intensification of gas flux from deep sources, triggered by neotectonic movements in the study area. [ABSTRACT FROM AUTHOR]

• Energy storage efficiency for analysed system ranges from 56.4% to 76.2% • Energy capacity of the system using 60,000 m3 post-mine shaft ranges from 6 to 78 MWh. • Levelized Cost of Storage for analysed system ranges from 314.6 to 439.4 €/MWh. • The higher the pressure in the low-pressure tank, the higher the energy capacity. • Economically, it is most preferable to use low pressure in the low-pressure reservoir. The paper presents the results of thermodynamic and economic analysis of a compressed carbon dioxide energy storage system using low-pressure reservoir, where carbon dioxide cannot be stored at a high-pressure, like in standard concepts. Such limitations may occur in post-mining underground excavations, the availability of which will increase in the coming years due to the ongoing decarbonisation of economies in many countries. In this paper the concepts of two systems using an isobaric high-pressure tank and a non-isobaric low-pressure reservoir which are built within a post-mine shaft are presented. The paper presents the results of technical analysis for systems with various structures. The results of the analysis show the storage potential and effectiveness of the compressed carbon dioxide energy storage system, which includes one, two or three sections of carbon dioxide compressor together with thermal energy storage tanks and the same number of expander's sections. The analyses were carried out for various ranges of allowable pressure change in the low-pressure reservoir. The paper identifies the pros and cons of the systems, such as high values of energy storage efficiency (which may reach almost 80%) and their technical complexity. The storage capacity and the required tank volumes were also assessed. For the system with single-section compressor and single-section expander, more in-depth analyses were carried out. The analyses were carried out for the assumed geometry of the mine shaft. For this solution economic analysis were also carried out. For the decision variables considered, the Levelized Cost of Storage ranges from 314.6 to 439.4 €/MWh. The inspiration for the development of the system was the high storage potential of underground mine infrastructure available in the region of the Upper Silesia located in Poland; however, the solution is universal and may be applied in other industrial regions. [ABSTRACT FROM AUTHOR]

The objective of this paper is to determine the origin and variability of methane and carbon dioxide concentrations in the near-surface zone and of coalbed methane in the SW part of the Chwałowice Trough and adjacent areas of the Main Syncline of the Upper Silesian Coal Basin (USCB). For this purpose soil-gas samples were taken at 202 measuring points, arranged along 5 profiles located in the mining area of the abandoned 1 Maja mine and directly adjacent areas as well as in the vicinity of four abandoned and remediated mining shafts. The maximum methane and carbon dioxide concentrations in the gas samples measured exceeds 22 and 9 vol%, respectively. The carbon isotope composition of methane and carbon dioxide was determined in samples in which elevated concentrations of these gases were found. Moreover, seven coalbed gas samples and bituminous coals were collected from coal seams exclusively from virgin parts of the Anna, Marcel, Jastrzębie, and Zofiówka mines. These data were supplemented with results of archival research for genetic interpretation of coalbed gases. Research reveals that typical humic low- and medium-volatile bituminous coals occur in Mississippian and Pennsylvanian coal-bearing strata in the study area. Fluctuations in methane and carbon dioxide concentration in the near-surface zone are related to the lithostratigraphy and tectonics of the area as well as to complicated methane depth distribution. Faults may play an important role in the microseepage of gases from deep to the near-surface zone. The connection of near-surface gases with subsurface gases was confirmed by similar stable carbon isotope composition in the methane recorded in the soil-gas samples and in the gas samples from the coal seams and sandstones of the Carboniferous formations. Distribution of anomalous methane concentrations recorded in soil-gas samples taken from profiles may indicate natural gas accumulations in the top zone of the Pennsylvanian coal-bearing formations. One example of this kind of accumulation is the Marklowice natural gas field, located within the mining area of the Marcel coal mine. Relatively high methane concentrations measured in soil gas in the vicinity of shafts I and III indicate that the degassing systems of closed and remediated mining shafts are not fully effective. Increases in carbon dioxide concentrations in the surface zone and frequent associated decreases in methane concentration were most often the result of microbial methane oxidation. • Both microbial and thermogenic methane zone of Upper Carboniferous strata occurs. • Accumulation of microbial methane in the upper part of Carboniferous strata occurs. • Results of soil gas measurements can help in location of free methane accumulations. • The degassing system of abandoned and remediated mining shafts is not effective enough. • Microbial oxidation of methane to carbon dioxide in the near-surface zone occur. [ABSTRACT FROM AUTHOR]

The paper provides the results of the inventory of greenhouse gases (GHGs) from road transport in Poland over the period 1990–2017. To estimate GHGs' emission from road transport, a standardized methodology was applied, consistent with 2006 IPCC Guidelines for National Greenhouse Gas Inventories and EEA/EMEP Emission Inventory Guidebook 2019, as well as the COPERT 5 software. In the analysis, emissions of fossil carbon dioxide, methane and nitrous oxide were taken into account. Emissions of all considered GHGs were converted to equivalent carbon dioxide. Throughout the subsequent years of emission inventory, emissions of all GHGs revealed an increasing trend, except for methane. The main cause underlying this increase is the dynamic development of motorization in Poland. Thus, GHGs' emissions were analyzed, taking into account the number of road vehicles and the intensity of their use. An increase in the average specific distance emission was found for fossil carbon dioxide (by ca. 5%) and for nitrous oxide (by ca. 10%), while for methane, there was a decrease (by more than 150%). The GHGs' emissions from road transport in Poland could be significantly lower if more emphasis was placed on the use of fuels from renewable energy sources. [ABSTRACT FROM AUTHOR]

The objective of this paper was to characterize the variability of methane (CH 4) and carbon dioxide (CO 2) concentrations in the near-surface zone, measured along 4 selected sampling lines positioned perpendicularly to regional fault zones, in the SE part of the Upper Silesian Coal Basin (USCB), Poland. This way it was possible to check the migration activity of these gases to the surface through low-permeable Miocene strata. It was also possible to evaluate the applicability of surface geochemical survey methodology to the identification of potential accumulations of free natural gas in the topmost parts of the Carboniferous formations in the USCB. The results of 319 soil-gas samples were supported by stable isotope analyses and related to the geological setting and the distribution of methane potential at various depths. Moreover, the sampling included the area of the closed and remediated Andrzej VII mining shaft, where 5 soil-gas samples were taken. Additionally, gas flux was evaluated at 3 measurement points at which increased gas concentrations were detected. The maximum concentrations of CH 4 and CO 2 in soil gases were 15.4 and 9.39 vol%, respectively. Soil gases contain both thermogenic and microbial CH 4 and CO 2 that migrated from secondary and primary gas zones within the Pennsylvanian coal-bearing strata. In some sites, CO 2 was also generated by the oxidation of soil organic matter and/or CH 4 in a near-surface zone. Anomalous CH 4 concentrations were generally found over elevated fragments of erosional structures of Carboniferous coal-bearing formations. This indicates the presence of free CH 4 accumulations beneath the Miocene overburden. However, the surface anomalies did not always correlate with the zones of CH 4 secondary accumulations. Anomalous concentrations of CH 4 and CO 2 correlated with the regional fault zones that cut through the Carboniferous formations. This indicates the potential presence of fault traps saturated with free CH 4 in the upper parts of Carboniferous formations. Relatively low values were observed for both CH 4 and CO 2 emissions (maximum: 25 and 4320 mg m−2 d−1, respectively). This suggests relatively low dynamics of gas migration from the depth to the soil zone. • Soil gases contain both thermogenic and microbial CH 4 and organic CO 2. • Anomalous CH 4 values are present over the erosional elevations of Carboniferous strata. • Anomalous CH 4 and CO 2 concentrations appear over the regional fault zones. • Gases migrate from secondary and primary CH 4 zones within the Pennsylvanian strata. • Concentration of CO 2 in soil gases is affected by changing seasonal conditions. [ABSTRACT FROM AUTHOR]