• Energy Research

In an overwhelming number of cases, the closure of a coal mine in Poland, for safety reasons, requires the installation of a pumping station and systems for the drainage of inflowing water due to its connection via roadways, goaves, or water-leaking pillars with other adjacent active mines. Due to operational costs, stationary pumping stations are being replaced with submersible pumping stations, wherever the geological/mining conditions allow this. The key factors to be considered when designing a submersible pumping station include the estimated water influx and the storage and emergency reservoir fill-up time. If the water level in the emergency reservoir exceeds the level of the maximum ordinate, there is the risk of water flooding an adjacent active mine, which poses a serious safety risk to this mine. A pumping station design must ensure that water can be pumped out also in emergency situations and must ensure permanent control over the level of the water table. The pumped-out water, after potential treatment, can be utilized as technological water in industrial plants. In the designed pumping station, it is also feasible to establish underground pumped-storage hydropower. This would enable the storage of energy from renewable sources, thereby contributing to CO2 emission reduction.

Accuracy of hydrogeological and geotechnical investigation in place of shaft sinking is a key factor for selection of sinking method and design of the shaft lining. The following work presents the influence of the rising level of accuracy of geological data gathered in the area of shaft sinking in the Silesian Coal Basin and technical projects of shaft lining and technology of its sinking, which have been changing over the years. The initial project of the shaft was repeatedly modified. Each modification eventuated in rising requirements for the shaft lining, such as increasing its thickness or changing concrete class. It has become necessary to use additional methods of reinforcing rock mass around the shaft.

Water is one of the most important resources found on Earth, essential for all forms of life. Both the quantity and quality of water resources are crucial for the health of the population and for economic sectors, making water a factor in determining a society’s standard of living. Mine water serves as an appealing source of both drinking and technological water. Regardless of the exploitation method, it must be pumped to the surface and, usually, treated to meet environmental standards. In most cases, it is discharged to rivers. In this article, we present a model of the use of mine water from three pumping stations of decommissioned coal mines in the Upper Silesian Coal Basin—Jan Kanty, Saturn, and Boże Dary. Water from these pumping stations is characterized by good qualitative and quantitative parameters. The results of the physico-chemical composition analyses carried out in the years 2012–2022 did not reveal any excessive amounts of toxic components or treatment difficulties. Given the long operational lifespan of these pumping stations and their existing water extraction infrastructure, they emerge as promising sources of both potable and industrial water supply, demanding minimal treatment efforts.

Excessive water inflow in a mine poses a great threat to its operation, especially in the case of a salt mine. In 1992, a rapid outflow of water occurred in the Mina traverse in the Wieliczka Salt Mine, and a number of investigations were undertaken to assess the causes of the outflow and the condition of the rock mass, including the gravity and microgravity surveys discussed in this paper. The first of these was to investigate the rock mass with respect to its geological, hydrogeological properties and mining. The aim of study was to monitor the changes in the rock mass density and the impact of these changes on the subsidence of the ground surface. The surveys provided information on the geological structure of the study area and helped to identify possible routes for water migration. The first data confirmed density changes in the shallow parts of the rock mass, manifested by subsidence of the land surface. However, the subsequent measurements failed to show any significant density changes in the shallow parts of the rock mass, despite the subsidence of the land surface. Therefore, it can be argued that the processes in the rock mass did not cause voids in the shallow parts of the rock mass that could lead to discontinuous deformations. These processes run deep and caused only continuous deformations in the form of subsidence basins.

Long-term coal mining activities in the Upper Silesia significantly affect the environment in southern Poland. Discharges of brines (with TDS reaching over 110 g/L) from mines are the main source of pollution of many rivers in Poland, including the Vistula River. The Zakrzówek horst is a small geological structure composed of the Upper Jurassic limestones. These limestones were exploited in several quarries. In the largest one (the “Zakrzówek” quarry), exploitation reached the depth of 36 m below the water table, i.e., about 32 m below the average water level in Vistula River which flows 700 m from the quarry. An important part of this inflow into quarries came from the contaminated Vistula River, with a chloride concentration over 2 g/L. The exploitation ceased in 1991, and dewatering ended in 1992. In the old quarry area, pit lakes appeared, which are unique because they present an example of a post-mining site affected by the riverine water contaminated with brines. Investigations of physicochemical parameters of water in the Zakrzówek area were carried out in the period of 1990–2020. Results showed that the largest pit lake was initially meromictic with a distinct stratification. After several years, holomictic conditions developed due to the surface layer freshening and convective mixing.

Chlorides are considered as an important factor promoting the development of the golden algae (Prymnesium parvum) and their presence was crucial during the Oder River ecological disaster in 2022. Since industrial waters from mining activities in the Upper Silesia region are discharged not only into the Oder River, but also into the other large European River (Vistula), there is growing concern about a possible re-occurrence of such an event. Combining catchment modeling and in-situ monitoring, the impact of mining discharges from 17 active and inactive hard coal mines on the calculation profile of the Vistula River, located in a potential risk zone of golden algal blooms, has been investigated. Moreover, future chloride concentrations have been predicted through model simulations for two time horizons: near- (2024–2050) and far-future (2074–2099), and for two Representative Concentration Pathways: RCP 4.5 and RCP 8.5. The results showed significant variability in chloride concentrations with monitoring data, indicating concentrations already exceeding those observed during severe algal bloom events. Furthermore, despite the selected scenario and time horizons, the simulated chloride concentrations may still promote golden algae development under both dry- and wet-climate scenarios, with extreme values potentially surpassing 3000 mg/L. Our results emphasize the urgent need for proactive water management strategies to reduce chloride contamination, and to protect aquatic ecosystems in this river. Failure to act in this area may lead to a repetition of catastrophic ecological events.

The energy sector in Poland is primarily based on fossil fuels, mainly coal. Hard coal mining is one of the most important industries in Poland. Hard coal deposits in Poland are found in three basins, but mining is currently carried out in the Upper Silesian Coal Basin (USCB) and the Lublin Coal Basin (LCB). The Upper Silesian Coal Basin is Poland’s central hard coal basin, with the most significant coal production extending across Poland and the Czech Republic. Approximately 80% of proven hard coal resources in Poland are found in the Upper Silesian Coal Basin (USCB). There is a tremendous amount of water in active and abandoned hard coal mines, which must be drained daily. Relatively high temperatures characterize mine water. This study analyzed the geological and hydrogeological conditions of the Upper Silesian Coal Basin and determined the potential for the use of mine waters for energy purposes. Depending on the location of the mine, the volume of mine water inflow ranges from 1 to 60 m3/min. The temperature of the pumped water is between 13 and 25 °C. In Poland, several such pilot installations have already been created; it is worth taking a closer look at the following examples. Heat recovery from mine drainage water can significantly reduce atmospheric emissions, which is particularly important in mining areas affected by low emissions. Therefore, Poland must raise the issue of using mined water for energy purposes, especially when making decisions related to decommissioning mines and developing post-mining areas.