The Abandoned Underground Cherno More Coal Mine (SE Bulgaria) - a Source of Low Grade Geothermal Energy

Bojadgieva, Klara; Benderev, Aleksey; Gerginov, Peter; Hristov, Vladimir

doi:10.7546/cr-2013-66-4-13101331-13

Cited by 4 publications

(2 citation statements)

References 1 publication

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“…Populations on the territory of present-day Bulgaria have used thermal and mineral waters since ancient times. The conditions and factors for their formation, distribution, qualities and potential uses have been the subject of numerous studies (Dobrev, 1912;Penev, 1927;Azmanov, 1940;Kusitaseva and Melamed, 1958;Shterev, 1964;Petrov et al, 1970;Velinov andBojadgieva, 1981, 1998;Pentcheva et al, 1997;Vladeva et al, 2000;Bojadgieva and Gasharov, 2001;Bojadgieva et al, 2010;Galabov and Stoyanov, 2011;Benderev et al, 2016, Hristov et al, 2019. Despite of the country's relatively small area of approximately 111,000 km 2 , there are 630 springs and wells located in 170 geothermal fields.…”

Section: Geological and Hydrogeological Backgroundmentioning

confidence: 99%

Mineral water bottling in Bulgaria

Hristov¹,

Valtchev²,

Trayanova³

et al. 2023

GeolBalc

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Bulgaria is rich in sources of mineral water of temperatures in the range of 25 °C–100 °C and various chemical compositions due to diverse geological and hydrogeological conditions. A large portion of the reservoirs of low-mineralisation water is suitable for bottling. Most of them are situated in Southern Bulgaria and related to fractured hydrothermal systems, while in Northern Bulgaria mineral waters of low mineralisation are formed in the relatively shallow levels of artesian aquifers. In the last 30 years, the utilisation of bottled mineral water has increased and, currently, there are at least 18 bottling facilities, while 12 others have closed down for various reasons. The purpose of the present study is to characterise the chemical composition of the Bulgarian mineral waters utilised for bottling, in terms of geological setting, quality, compliance with regulations and possible problems associated with mineral deposition and corrosion. The water type largely depends on the host rocks. In most cases, sodium-type waters are utilized and, in the case of anions, bicarbonate and sulphate. The only exceptions are the waters formed in limestone, dolomite and marble, which are calcium-bicarbonate and calcium-magnesium type.

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Section: Geological and Hydrogeological Backgroundmentioning

confidence: 99%

Mineral water bottling in Bulgaria

Hristov¹,

Valtchev²,

Trayanova³

et al. 2023

GeolBalc

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“…With the regard to these advantages mine water heat recovery is becoming more widespread in the post mining areas of Europe and the United States, which reduces fossil fuel consumption and facilitates "green energy" devel opment [5]. Currently almost 30 geothermal systems installed at closed mines with thermal capacity of 0.35 to 4.6 MW are under operation in different countries, most of them are situ ated in the Ruhr coalmining area of Germany [6].…”

Section: Introductionmentioning

confidence: 99%

Validation of the operation efficiency criteria for geothermal probes in flooded mine workings

Rudakov¹,

Inkin²

2020

Nauk. visn. nat. hirn. univ.

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Purpose. To develop and test the energy and cost criteria for evaluating the operation efficiency of a closed geothermal system using coaxial or U-shaped probes that can be installed in flooded workings of mines. Methodology. To justify the energy and cost criteria, we applied thermodynamic, hydraulic and cost-efficiency relationships, conducted the engineering analysis of closed geothermal systems, studied hydrogeological settings and geothermal conditions of the mines of the Selidovo group in Donbas. The developed criteria were examined within the ranges of key parameters such as the flow rate of the heat transfer fluid and the probe submerged length. Findings. We quantified the influence of the probe submerged length and the heat transfer fluid flow rate on the energy balance and the net present value NPV and identified the parameter combinations that allow achieving efficient heat recovery in terms of energy balance and cost-efficiency. The produced/spent energy ratio may reach 1.52.2 and the NPV a few dozen thousand when increasing the submerged depth to 500 m at the flow rate of 20m3/d. A higher flow rate may lead to a negative energy balance but the NPV remains positive within some ranges of the probe submerged length, thus, indicating the system profitability. The payback period can be shortened to a few years. Originality. The proposed energy criterion balances the thermal energy produced and the thermal equivalent of electric energy generated using fossil fuel and spent on system operation. This ratio as distinct from the usually applied COP parameter allows comparing the energies of the same nature and drawing more adequate conclusions on environmental acceptability of a geothermal system. Practical value. The proposed criteria can be used for prioritization of geothermal system installation and the operation efficiency evaluation among the number of potential sites in post mining areas.

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Evaluation of heat supply with maintaining a safe mine water level during operation of open geothermal systems in post-coalmining areas

Rudakov¹,

Inkin²

2022

Min. miner. depos.

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Purpose. Evaluation of the efficiency of open geothermal systems in flooded and drained mines of the Donetsk basin for heat supply of buildings with maintaining a safe mine water level. Methods. Both circulation and non-return geothermal systems for the mine water heat recovery are analyzed. We proposed the energy and cost criteria for evaluating the effectiveness of open geothermal systems based on a comparison of the produced thermal energy with the energy costs for its production. The criteria use the relationships of thermodynamics, hydraulics, analytical formulas for calculation of ground water flow and methods to calculate the heat demand of indoor spaces. Findings. The estimated ranges of thermal capacity from a few tens kW to a few MW and a coefficient of performance (COP) conversion factor of 3.5-6.8 achievable by geothermal systems for the studied closed mines of Donbas correlate well with the values of these indicators at open geothermal systems operated in different countries, which shows the technical and economic feasibility of the installation to cover local heat demands. The possibility to fully cover the needs for thermal energy is shown on the example of buildings with office spaces for staying of a few hundred people. We demonstrate how to preliminary calculate the parameters of mine water circulation with maintaining the safe level in terms of keeping the ground water quality in the areas adjacent to the mine. Originality. The developed criteria and calculation methodology allow to realistically evaluate the parameters of the efficiency of operation for open non-return and circulation geothermal systems, taking into account mining, geological and technology conditions, to prioritize the exploration of geothermal resources in mines and to evaluate the parameters of mine water circulation with maintaining the safe mine water level. Practical implications. The study showed the feasibility of installation and effective operation of open geothermal systems at the mines of the Donetsk basin for heat supply of buildings located in the adjacent areas with maintaining a safe mine water level.

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The Abandoned Underground Cherno More Coal Mine (SE Bulgaria) - a Source of Low Grade Geothermal Energy

Cited by 4 publications

References 1 publication

Mineral water bottling in Bulgaria

Mineral water bottling in Bulgaria

Validation of the operation efficiency criteria for geothermal probes in flooded mine workings

Evaluation of heat supply with maintaining a safe mine water level during operation of open geothermal systems in post-coalmining areas

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