Evaluation and statistical interpretation of low-temperature geothermal energy potential for selected locations in Poland

Abstract

Fulfilling the binding national, EU and other international regulations and requirements on climate and energy implies significant growth of renewables share in the total mix of energy production in Poland. Low-temperature geothermal energy extracted with the use of the ground source heat pumps (GSHP) is an efficient and reliable source for space heating, cooling and seasonal thermal energy storage and recovery, thus it contributes to reduction of low emissions and improvement of air quality. GSHP effectiveness is to a high degree determined by local geological and hydrogeological settings, therefore identification of natural properties of the subsurface is crucial for appropriate design and subsequent operation of the GSHP installations. The thermal conductivity l of rocks and soils, a key geothermal parameter, depends on such features as the mineral composition of rocks and soils, their texture and water content. Relevant geological data is retrieved from thematic databases, atlases and serial maps and can be gathered in a unitary database with a uniform structure to enable spatial analysis with the use of GIS techniques. Reclassification of lithological properties into geothermal parameters and subsequent calculations of λ values (W/m·K) of rock and soil types can be made using a specific algorithm. The results of these calculations enables computation of four spatial layers of average geothermal conductivity coefficient λ (W/m·K), respectively for the depth intervals of 0–40, 41–70, 71–100 and 101–130 metres b.g.l.