| Title | Geothermal Trenches for Recycling of Waste Heat from Closed Seasonal Thermal Energy Storage Facilities |
|---|---|
| Authors | Bott C, Hoffmann D, Akbar S, Müller S, Bayer P |
| Year | 2026 |
| Conference | World Geothermal Congress |
| Keywords | |
| Abstract | Seasonal thermal energy storage (sTES) is a key technology for innovative low-emission energy systems. The Reno-sTES concept focuses on transforming existing in-ground basin infrastructures into low-insulated sTES facilities. While this approach aims to reduce material and energy consumption in comparison to new installations, a weakness of large basins formerly used for other purposes is their limited thermal insulation in combination with unfavourable geometry, especially if they are situated in an environment with groundwater flow. Heat losses of such sTES, and any other buried “warm” infrastructure, cause adverse heat accumulation and temperature rise in the ambient ground(water), as this may negatively affect the environment. Our study proposes implementing geothermal trenches next to Reno-sTES as a solution: A vertically arranged ground heat exchanger, connected to a heat pump, is placed in the groundwater downstream of such an installation to capture heat losses. In a first feasibility study, an extension of the proven water-gravel sTES co-simulation framework “STORE” is presented. It features the geothermal trench as a novel component to analyse the benefits of this technology enhancement from an energetic (e.g., storage/system efficiency, amount of recycled heat) and environmental (i.e., moderated temperatures in the surrounding subsurface) perspective. Results reveal a high potential of the proposed solution: On the one hand, dissipated heat losses can effectively be captured by the trench, enhancing the overall efficiency of the combined sTES-trench system. On the other hand, environmental impacts can actively and effectively be mitigated, as temperatures can be kept below thresholds for ground and groundwater protection. |