gews GEWS

Project title: Verbundvorhaben: Entwicklung und Bau eines tiefenhorizontierten Geologischen Eis-Wärme-Speichersystems (GEWS) als Demonstrationsanlage auf dem Testfeld TestUM/Wittstock (Development and construction of a deep-horizontal geological ice heat storage system (GEWS) as a demonstration plant at the TestUM/Wittstock test field)

Teilprojekt TP5: Numerische Modellierung durch Frost-Tau-Wechsel induzierter Oberflächenverformungen / Numerical modeling of surface deformations induced by freeze-thaw cycles

Project description: One of the proposed solutions to the above challenge is the use of geothermal heat pumps for building heating and cooling. Geothermal heat pump technology is currently growing rapidly in Europe and around the world. In the joint project "Development and construction of a deep-level geological ice-heat storage system (GEWS) as a demonstration system on the test field TestUM / Wittstock", the conventional geothermal heat pump concept is being further developed. It is suggested that the circulating fluid in the borehole heat exchangers operates below the freezing point of water and thus more energy is recovered from ice formation in the shallow aquifer. If the latent amount of heat is completely extracted, the GEWS can supply larger building areas with a smaller number of geothermal probes, which brings with it attractive cost-saving potential. Another advantage of GEWS is that the ice that has formed underground can be used in summer to supply cold water or for air conditioning. This further reduces operating costs, which is particularly beneficial for commercial buildings such as shopping malls. As part of the GEWS project proposal, a system with 9 geothermal probes will be built on a test field together with temperature sensors and groundwater monitoring probes. The task of the UFZ-INVINF is sophisticated modeling of ice storage for optimal design and use.

Project duration: 10/2021 - 09/2023

Project funding / support: Bundesministerium für Bildung und Forschung (BMBF) / Projektträger Jülich, Forschungszentrum Jülich GmbH, „PTJ-MGS“

bmbf ptj

Project partner

  • Universität Kiel (CAU) – Projektkoordinator
  • Helmholtz-Zentrum für Umweltforschung GmbH UFZ (Departments ENVINF, ISOBIO, MET)
  • Fraunhofer-Einrichtung für Energieinfrastrukturen und Geothermie – Fraunhofer IEG

Project team ENVINF: Dr. Haibing Shao (Teilprojektleitung), Dr. Tymofiy Gerasimov

The project aims at modeling the freezing and thawing processes in partially and fully water-saturated soils. This is (a) to understand and quantify an impact of ice formation and utilization of the latent heat of ice fusion on the efficiency of the ground source heat pump systems (GSHPS) coupled with borehole heat exchanger (BHE), and (b) to describe and study the effect of frost heaving (soil volume deformation due to ice formation) – see e.g., Figure 1 for illustration – which may result in damage of infrastructure. To this end, the existing and newly developed three-phasic thermo-hydro-mechanical formulations for saturated porous media which account for water-to-ice transition will be implemented in the UFZ open-source environment OpenGeoSys-6 with a consequent verification and validation using the experimental data and parameters obtained from the full-scale test-field TestUM / Wittstock.

gews gews Prototypical simulation results of a coupled thermo-mechanical analysis of a fully
water-saturated soil block around a BHE which contains a refrigerant fluid under negative
(-15°C) temperature: (a) geometry, (b) temperature distribution within the block after 720
hours (30 days) of cooling, (c) formation of ice, and (d) the induced soil deformation.

Links (intern): overleaf, cloud