Preliminary comparative analysis of underground thermal energy storage, shallow and deep geothermal energy solutions for sustainable district heating in Poland

Abstract

This paper explores shallow and deep energy technologies supporting Poland’s district heating transition, focusing on aquifer thermal energy storage (ATES), borehole thermal energy storage (BTES), deep geothermal energy, and energy piles. Heating accounts for a major share of energy consumption and emissions in Poland, where district heating networks are essential for urban energy supply. National policies promote renewable energy integration and energy security, presenting opportunities for geothermal and underground thermal storage solutions. ATES and BTES offer seasonal heat storage by cycling thermal energy in subsurface aquifers and boreholes respectively, balancing variable heat demand and renewable supply. Deep geothermal energy provides stable base- -load heat via extraction from deep reservoirs, contributing reliable renewable heat despite requiring significant investment and geological specificity. Energy piles represent an innovative technology, combining building foundation piles with embedded heat exchangers, enabling efficient ground heat use for heating and cooling without additional land or deep drilling. This method is especially suited for urban environments and contributes to cost-effective decarbonization. The paper compares technical principles, geological conditions, performance, economic and environmental aspects of these technologies, highlighting their complementary roles in enhancing heat network flexibility, efficiency, and sustainability. The findings inform strategic planning and policy development to optimize Poland’s renewable heat infrastructure, supporting climate targets and energy independence for widespread adoption.