Regional infrastructure repurposing: Pathways from assessment to geothermal energy production and storage

Addressing the growing demand for sustainable energy, we explore the innovative potential of repurposing existing subsurface infrastructure for geothermal energy production and energy storage. We present an integrated technical, economic, and legal framework for repurposing regional-scale infrastructure to systematically evaluate and optimize geothermal resource utilization. The states of Berlin and Brandenburg in Germany serve as a model area, with field studies in Groß Schönebeck and Lusatia demonstrating practical infrastructure repurposing. Results show that 12 of the 17 evaluated wells are potentially suitable for repurposing, with hydrothermal energy (HE) emerging as the most promising option. Economic viability is achievable by targeting the Middle Buntsandstein formation at depths exceeding 2400 meters and temperatures above 86 ∘ C, utilizing well doublets with a minimum of 750-meter spacing. Reservoir simulations indicate that optimized development schemes can achieve gross thermal power ranging from 2.9 to 7.6 M W t h with a Levelized Cost of Heat (LCOH) ranging from € 0.035/kWh to € 0.08/kWh. This is achievable through exploration near existing wells and direct connection to district heating networks. While Borehole Heat Exchangers (BHEs) offer faster implementation, their economic viability is challenging due to low thermal power and proximity requirements. Recognizing a mismatch between existing subsurface data and heat demand areas, the Landesamt für Bergbau, Geologie und Rohstoffe (LBGR) has initiated a new 2D seismic exploration campaign in 2025 for the Lower Lusatia area, leveraging well-established district heating and hydrocarbon infrastructure. This research demonstrates an economic strategy for reusing infrastructure for heating and energy storage, supported by strategic government initiatives, and provides a replicable decision-making workflow to guide geothermal energy development.