Polski
Geothermal in Poland
Underground waters of natural origin with elevated temperatures at the outflow are called geothermal waters. According to the current Geological and Mining Law (Journal of Laws 2011, item 981), in order for groundwater to gain thermal status, it must have a temperature at the outflow higher than 20°C. Both thermal waters and therapeutic waters and brines are minerals under the law, and their exploitation requires a license. Unlike deposits of, for example, coal (also a fossil, but non-renewable), geothermal waters are considered a renewable resource, and the use of their thermal energy is one type of renewable energy source (RES).
Conditions in Poland favor the direct use of thermal waters and their energy. The largest resources and high potential of groundwater stored in aquifer rocks are found, among others. In the Inner Carpathians, specifically in Podhale. The Podhale Trough is one of the most valuable geothermal areas in Poland. The geothermal waters mined there are characterized by relatively low mineralization (1-3 g ), which avoids many of the problems associated with the operation of technical equipment, both with the hydrogeological borehole and with heat recovery systems.
Observed temperatures of geothermal water in the Podhale Basin region range from ca. 20°C to 86°C. These temperatures are usually considered too low for electricity production, but sufficient to exploit their potential for a wide range of other services, i.e. In drying and heating plants, fish farming or crop cultivation, etc. In the Podhale area, their recreational use in swimming pools is predominant.
The possibility of using geothermal water resources is provided by the high renewability of the deposit. Thus, the region of the Podhale Basin is an excellent example of the rational use of geothermal water resources. One of the facilities operating here is the Chocholow Thermal Baths. This complex will soon see the installation of an innovative and first ORC (Organic Ranking Cycle) device to produce electricity from water at a temperature of approx. 86°C.
Geothermal complex – renewable energy source or environmental burden?
It is widely recognized that RES is environmentally friendly and promotes the reduction of emissions from conventional energy sources, such as the burning of fossil fuels. The process of extracting geothermal water, as well as recovering thermal energy from it, does not lead to any pollution. They usually lie at considerable depths (on the order of several kilometers) and thus do not affect the land surface, are not a nuisance to residents and do not generate noise. With regard to geothermal, the arguments raised by RES opponents do not apply.
They do not entail the use of large areas – the well itself, along with the casing and the direct protection zone, usually takes up approx. Severalsquare meters of land. It does not pose a threat to plant or animal organisms (such as the often-cited potential collisions of birds with windmills) and does not lead to a loss of watercourse permeability (as in the case of hydropower). So does the use of geothermal resources not burden the natural environment in any way? The correct answer to a question phrased this way is, “It depends.”
The operation of facilities using geothermal water leads to the generation of used water, which by law constitutes wastewater and requires proper discharge into the environment. These waters, due to their temperature and usually high mineral content, can pose a potential threat to the environment. Thus, there are various ways to “dispose” of them. The technically and economically simplest is direct discharge into surface watercourses. However, it is necessary to meet the conditions specified in the water permits so that the wastewater is of adequate quality and does not pose a threat to aquatic ecosystems. This course of action is possible in the Podhale region, where raw geothermal waters have low mineralization.
When the captured geothermal waters are highly mineralized, being often brines, there is no possibility of discharging them into surface watercourses and there is a need to inject them back into the rock mass. For this purpose, the so-called “new” must be realized. A doublet of holes, one of which is an exploitation hole and the other an absorption hole. This is an environmentally unobtrusive option, but requires significant investment due to the need to drill two deep boreholes instead of one.
Chocholow Termy as an environmentally friendly facility
Chocholow Termy since 2016. are doing business in Podhale in the area of recreation and tourism. They operate thanks to geothermal water from the Chocholow PIG-1 well.
Chocholowski Thermal Baths implements a broadly sustainable development policy of caring for the environment and supporting community development while implementing horizontal policies. The thermal baths are carrying out a number of activities to counter environmental degradation. In addition to using renewable energy sources (a geothermal source) to produce heat for the pool complex, they are also trying to reduce their environmental impact in all their processes.
Particularly noteworthy is the use of modern technology in the thermal water treatment process, which does not adversely affect the surface water recipient. Thanks to the use of nano-silver in the water treatment process, it was possible to exclude activated carbon (which was a dangerous technological waste) from the filter bed, and thanks to three-stage disinfection, the effect of bacteriologically clean and healthy pool water with a significantly reduced dose of sodium hypochlorite was achieved.
The operation of the pool complex produces used thermal water that needs to be discharged into the environment. The conditional concession stipulated that the handling of the used thermal waters after 2025. will involve injecting them through an absorption well into the rock mass. A temporary exemption has been obtained, and the thermal waters used are now being discharged into the Black Dunajec River (under the terms of the water permit). The facility is equipped with an off-road aeration and cooling cascade with an outlet to the stream.
Under the license currently in effect, and in accordance with the provisions of the environmental decision, handling of the used thermal water in a manner other than injection back into the rock mass through an absorption well is possible until December 31, 2025. At the same time, the decision amending the 2015 environmental decision stated that “the introduced requirement for water injection is not a mandatory condition for this type of project, and its introduction, without a prior impact assessment, should be considered premature.” Thus, if it is demonstrated that there is no negative impact of discharging used thermal waters into the Black Dunajec River, based on the analysis of multi-year data, it would potentially be possible to continue using this solution. The choice between discharging wastewater into a surface watercourse and injecting it should be based on the results of environmental analysis and the technical and economic capacity of the company.
An assessment of the impact of discharging used thermal waters on aquatic organisms and habitat conditions in the Czarny Dunajec River was carried out as part of a collaboration between Chocholow Thermal Baths and the University of Agriculture in Krakow.
Assessment of the impact of discharging used thermal waters on organisms inhabiting the Black Dunajec River
The water user is obliged under the terms of the water permit not to exceed the parameters of the discharged wastewater. However, despite this condition, a potential negative impact on aquatic organisms and their habitat conditions is possible. Therefore, Chocholowski Thermal Baths has commissioned an assessment of the impact of discharging used thermal water into the Czarny Dunajec stream based on monitoring results to date.
Aquatic macroinvertebrates (common indicators of ecological status/potential of waters) were used as a model group for biocenotic studies. Because of their sensitivity to changes in the aquatic environment (often those related to human pressures, such as saprobation, eutrophication, acydification or hydro-engineering regulations), these organisms are commonly used to assess rivers and the integrity of aquatic ecosystems and in environmental risk diagnostics.
Studies of benthic macroinvertebrates and hydromorphological conditions (inventory of microhabitats) were carried out in sections located about 100 m above the thermal water discharge site (reference sections, outside the impact of Chocholowski Thermal Baths), right at the outlet and about 100 m below it. The surveys were conducted using the kick-sampling method, in accordance with the standards for conducting macrozoobenthos surveys used in state environmental monitoring. Based on the collected material, the following indices were calculated: abundance, taxonomic richness, diversity, and the biotic index %EPT (% share of pollution-sensitive individuals, taking into account mayflies Ephemeroptera, forkbeards Plecoptera and caddisflies Trichoptera).
Throughout the study area, similar habitat conditions were observed, resulting primarily from the morphology of the Black Dunajec River channel. This watercourse is an example of a mountain river that has been subjected to strong, albeit spatially varied, anthropopressure (hydro-engineering regulations, gravel mining and deep erosion) over its considerable length over the past several decades. Only at the point of discharge of pool waters is there an artificially made rapids, which, however, ensures the proper existence of aquatic fauna, and due to the greater turbulence of water in this area, accelerates the mixing of water discharged from the thermal baths with the waters of the Black Dunajec.
Analysis of the studied parameters of aquatic macrofauna did not show a statistically significant effect of the discharge of used thermal waters on the studied bioindicators, and thus on the ecological quality of the waters of the Black Dunajec River. Abundance, taxonomic richness and diversity, as well as the % EPT index, had similar values in the water in all surveyed sections. The effect of the discharge on the taxonomic composition of macroinvertebrates in each habitat was also not recorded – it was similar, regardless of the location of the studied section.
The results of the study indicate that the discharge of used thermal water does not have a negative impact on aquatic macroinvertebrate assemblages.
Summary
The above analysis shows that the conditions of the existing water permits for the discharge of used thermal waters into the Black Dunajec River do not pose a risk to aquatic organisms living in them.
The use of geothermal water resources, although classified as an environmentally friendly renewable energy source, under conditions of domestic use mainly for recreational and bathing purposes, is associated with the need to discharge into the environment used geothermal water, classified by law as wastewater. Nevertheless, the choice of how they are discharged into the environment (into surface water or into the rock mass), the use of modern and effective solutions and monitoring make it possible to minimize the burden on the environment and even make its impact on natural components imperceptible.
Ph. Renata Kędzior is a professor at the University of Agriculture in Cracow and works in the Department of Ecology, Climatology and Air Protection. He conducts research in the field of engineering and biological sciences. He works on issues related to water ecology and the use of bioindicators in human environmental impact assessments.
Ph. Eng. Agnieszka Operacz is a professor at the University of Agriculture in Cracow and works in the Department of Sanitary Engineering and Water Management. He conducts research in the field of engineering and technical sciences. He is involved in water management, specializing in hydrogeology with a particular focus on geothermal and therapeutic waters, combining natural and engineering issues.
MA. Eng. Agnieszka Zachora-Bulawska is pursuing an implementation doctorate in the Department of Sanitary Engineering and Water Management at the University of Agriculture in Cracow. At the same time, he works as deputy head of the Technical Department/R&D Department of Chocholowski Terme.
Bis B., Mikulec A. (eds.), 2013. A guide to assessing the ecological status of rivers based on benthic macroinvertebrates. Environmental Inspectorate. Environmental Monitoring Library. Warsaw, 127 pp.
