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In Poland, thermal waters of economic importance can be found throughout the Lowland of Podhale in the Early Cretaceous or Early Jurassic formations, in the Carpathians (Podhale Basin), and in the Sudeten. According to the Polish law the thermal waters with the outlet temperature exceeding 20 °C are considered as minerals. The extraction of thermal waters for the therapeutic and medical purposes has a long tradition in Poland and the earliest records of this date back to the 13th century. Currently such waters have been documented in 24 water intakes situated in 14 different locations while still 11 of them are actively working health resorts.
Research on geothermal heat flow in Poland base on the oil and gas drilling, which has been conducted since the 1960's. Studies focused on heat of the thermal waters applications have started 15 years ago. Those types of research evolve rapidly and they are supported from the state budget. The main objective of those studies is to meet the EU commitments concerning the increase of renewable sources of energy in gross inland energy production. In order to asses the possible use of thermal waters with the temperature of 86 °C and mineralised at less than 3.12 g/dm3 as sources of energy, detailed geological works were undertaken in 12 boreholes in Podhale Basin and 2 in the Sudeten. In the region of Polish Lowland the possible extraction of thermal waters within the range of 40-88 °C from porous aquifers were investigated in 12 boreholes. The level of mineralisation of analysed waters ranged from 0.5 to 126 g/dm3. Thermal waters are utilized for the heating purposes in 5 geothermal plants in Poland (boreholes depth varies from 1625 to 3572 m). In four of these plants the cooled water is injected back into the rock formation, while in the fifth one it is used as tap water by the municipal water-pipe network. In two of the plants the boreholes were originally drilled for other purposes and were adapted for the extraction of thermal waters. The remaining boreholes were originally designed for thermal water heat acquisition.
Heat acquired from the thermal waters changes throughout the year and it depends mainly on the climate and the needs of the energy consumers. In general geothermal plants can process more energy than is currently used, so temperature of the water injected back into the rock formations is higher than was originally intended. The main problem with the extraction of this mineral is the high aggressiveness of the waters taken, as well as the difficulties with injecting them back into the porous aquifers. In the case of salt-springs, it is necessary to carry expensive works every 2,5 years in order to increase the absorptivity of the boreholes used for injection.
Within this work the current state of knowledge and the experience gained by the Polish experts in the field of the thermal waters extraction and utilisation for both therapeutic/medical and heating purposes will be presented.
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