Cost Analysis for Large Thermal Energy Storage Systems

Abstract Thermal energy storage (TES) technologies play a key role in decarbonizing heat supply and integrating renewable energy sources into heating systems. This study examines the investment costs of over 50 large-scale TES systems, including aquifer thermal energy storage (ATES), borehole thermal energy storage (BTES), pit thermal energy storage (PTES), and tank thermal energy storage (TTES) systems, based on desk and literature research. The analysis considers inflation and purchasing power parity to enable cost comparisons between regions and time periods and develops cost functions to enable investment appraisal. The results highlight significant differences in the cost structures and the scalability of TES technologies. PTES systems benefit from economies of scale, making them cost-effective for large storage volumes. Due to higher specific costs, TTES systems are more suitable for smaller applications. ATES and BTES systems show moderate economies of scale. However, they remain highly dependent on geological conditions. Furthermore, the study introduces a new framework for calculating the levelized cost of storage, which enables the comparison of different technologies by considering the cost of providing energy at the target temperature level. This framework provides a more accurate assessment of the relative competitiveness of TES. By providing a transparent basis for evaluating TES cost, the study's findings reduce uncertainty for decision-makers. Furthermore, the study recommends additional research to validate cost models and assess the practical application of TES.