GeoTES

July 1, 2022 – June 30, 2025

The use of seasonal high-temperature aquifer storage systems (HT-ATES) in combination with large-scale heat pumps has not yet been adequately addressed. Therefore, the goal of the GeoTES collaborative project is to develop a mathematical model for an optimized above- and below-ground heating system, as well as for its integration into heating and electricity grids. The GeoTES concept involves extracting heat from deep aquifers with temperatures exceeding 40°C to supply heat pumps and integrate them into heating networks. The aquifer storage systems are to be recharged using a large-scale heat pump powered by renewable energy, as well as industrial waste heat and solar thermal energy. Due to the thermal capacity of the geological subsurface, which offers high and low temperatures available year-round, the efficiency of large-scale heat pumps, and the use of renewable energy sources and industrial waste heat, the project pursues a sustainable approach to implementing the heat transition. The development of a comprehensive geothermal storage concept for heating and cooling supply is to be carried out using the example site of Burgwedel in the Hanover region. The deep thermal waters at this site, with their high salt content, represent typical conditions for the northern German region. The excellent seismic exploration data for the pilot site and the results of a nearby deep borehole allow for a comprehensive reservoir characterization of the thermal water-bearing sandstones. Similar geological conditions with suitable sandstone formations are found in deep aquifers across large parts of Germany.

GeoTES consists of a total of five subprojects (SP). As part of the first subproject, a numerical reservoir model for simulating ATES systems is to be developed using the open-source simulator DuMu^x, which takes into account both geohydraulic and geochemical effects as well as storage efficiency and operational safety. SP2 focuses on above-ground supply systems, which will be integrated into a comprehensive model. For this purpose, a generally applicable neighborhood model will be created, along with standard load profiles representing the electrical load side. Furthermore, the development of a strategy for the system integration of large-scale heat pumps is planned. The third subproject involves the optimization of well and production parameters. To this end, a thermal well model is to be coupled with the reservoir and neighborhood models and extended for application to multiphase fluids. The objective of WP4 is to create an integrated ATES simulation model and apply it to the example site in Burgwedel, where both different borehole configurations and alternative configurations for storage optimization will be tested. The models will be formulated in a general manner and parameterized using the available data from the example location. In addition to validating the modeling approaches, this will enable the transferability of the overall model to other sites. The fifth subproject is dedicated to project coordination. Ultimately, the GeoTES project aims to identify the possibilities and limitations of using thermal energy storage in aquifers for the emission-neutral energy supply of new and existing neighborhoods, regardless of location, and to provide numerical simulation tools for this purpose.