UTES in Berlin: a systems approach to heat storage, usage, and heat pollution mitigation

Dense urban areas like Berlin face unique challenges when instituting geothermal energy, especially understanding how subsystems (e.g., transportation, people, legal framework, deep subsurface, drinking water, etc.) are linked and how the larger system is affected by changes to subsystems. The innovative approach to viewing a city as a system composed of subsystems and integrating the subsystems in a holistic energy efficiency framework is required to prevent unforeseen adverse consequences of actions such as heat pollution from thermal energy storage in deep reservoirs. The interaction between U-Bahn tubes, HT-ATES/BTES systems, groundwater flow, and the urban heat island creates a tightly coupled thermomechanical environment in which temperature, pore pressure, strain, and geochemical states evolve simultaneously and govern system efficiency and structural stability. In Berlin-Adlershof, an HT-ATES research well was completed in 2024 and drilling of the injection and production wells are slated for this year. Our new work will demonstrate the efficacy of: 1. HT-ATES in Berlin for thermal heat storage and production, 2. Using the subway system to collect heat and mitigate heat waste from the shallow subsurface heat island and heat pollution produced by HT-ATES wells. The interaction data from monitoring wells and a fiber optic experiment within the subway will provide parameters for thermomechanical models on granular scales (e.g., directly adjacent to wells, subway) and we will scale up models to interconnect ATES, subway, and groundwater, and then to district, city, and national levels. Social science and humanities data will be incorporated into the large-scale models to produce a structure for establishing UTES in other cities with unique settings in terms of geology, legal framework, drinking water sources, presence/ absence of mining, and other differences.