Energy potential of thermal waters in the Polish Lowland

The paper presents results of calculations of geothermal energy resources accumulated in the aquifers of Mesozoic and Paleozoic age in the Polish Lowlands. The analysis carried out in the project covered approximately 270 th. square km, that represents more than 87 percent of the territory of Poland. The calculations were made with regard to the classification of resources, in accordance with the McKelvey’s diagram. The static, static-recoverable geothermal resources and disposable geothermal reserves were distinguished. For calculation of disposable reserves the methodology of evaluation of economic factor efficiency of heat recovery was applied (the power factor). The methodology enabled preliminary assessment of the geothermal energy utilization profitability at the regional scale and indication of prospective areas within particular aquifers. Static geothermal energy resources accumulated in nine major reservoirs: Devonian, Carboniferous, Cisuralian, Lower Triassic, Upper Triassic, Lower Jurassic, Middle Jurassic, Upper Jurassic and Lower Cretaceousin the Polish Lowlands are estimated at 1.45 × 10²² J (3.47 × 10¹¹ toe). Total static-recoverable resources has been assessed at 2.9 × 10²¹ J (6.9 × 10¹⁰ toe). Total disposable reserves of geothermal energy accumulated accumulated in nine major geothermal reservoirs was estimated at 9.21 × 10¹⁸J/year, which corresponds to 220 × 10⁶ toe/year. It should be emphasis that admissible water and energy reserves can only be assessed after drilling operation and pumping measurements has been performed. Therefore, assessment of admissible energy resources on a regional scale is in principle not possible. Assuming the recovery of 1.5–2.5% of disposable reserves (Górecki et al., 2003), the admissible reserves of geothermal energy are estimated as 1.38–2.30 × 1017 J/year (3.3–5.5 × 10⁶ toe/year).