IGLU heat storage concept (Source: IGLU-Verbundprojekt 0325547, Constantin Kinias, SCHEER; Andreas Dahmke, CAU Kiel)

Project title: Untersuchung, Modellierung und Bewertung eines intelligenten geothermischen
Langzeitwärmespeichers mit umweltneutralem Verhalten – Teilprojekt: Monitoring, numerische Methoden und Hydromechanik
(Project title – English translation: Investigation, modelling and evaluation of an intelligent geothermal long-term heat storage system with environmentally neutral behaviour – Subproject: Monitoring, numerical methods and hydromechanics)

Short project description:
To compensate the increasing fluctuating supply of heat or cooling from renewable energies (e.g., solar thermal energy), there is an urgent need for the renewal and expansion of decentralised heat storage systems, which will be of central importance for the effective and efficient heat supply of buildings in future. Despite of some successful demonstration plants, currently it is not possible to assume that near-surface geological heat storage facilities will be sufficiently available for these tasks in the medium term. In the short term technologies with widespread use can be considered that on the one hand have low environmental impacts and on the other hand are largely robust, low-maintenance and economically efficient both in new buildings and in existing buildings. These requirements are largely in line with solid-water systems, which are still in a developmental stage. In the joint project IGLU individual module components for intelligent near-surface geothermal long-term heat storage systems with environmentally neutral behaviour were further developed and tested in their entirety in laboratory and pilot plants. The IGLU concept is based on the incorporation of a high thermal capacity water-absorbent thermal filling material directly beneath or in close proximity to buildings, which at the same time inhibits the heat transfer into the groundwater. These modules are equipped with an internal heat exchanger system. Special insulation ensures a reduction of heat loss into the environment.

The main aim of the project was the development and testing of an environmentally neutral, robust, economical and quantitatively relevant heat storage system with preferably modular components which can be realised in short term. The IGLU system components should be able to serve both for the seasonal long-term storage of heat and for the buffering of "surplus electricity". Areas of application include existing buildings as well as new buildings. In IGLU, aspects relating to the building materials used (thermal filling material, insulation materials, heat exchangers, etc.), the overall system development of the storage modules, the structural-technological process organisation and the construction and operation of the storage facility were processed to develop an effective, cost-effective and environmentally friendly storage system for low-temperature solar thermal energy.

Within the context of the research that has been conducted by the UFZ as part of the IGLU joint project, numerical methods for the analysis of the considered heat storage systems were developed and implemented in the open source software platform OpenGeoSys. In thermo-hydro-mechanically coupled models, the effects of cyclic processes during operation of the systems were considered. Scenario simulations focussed on the evolution of local stress fields in the storage modules as well as on temperature field studies. Various measuring concepts were evaluated with regard to their suitability for spatially and temporally adjusted monitoring during the operation of the heat storage systems and the results obtained were validated in field trials at the pilot site. The hydrogeological measurement and monitoring concepts are primarily necessary to ensure the environmentally-neutral operation of the considered storage systems. The project results can be used by research institutions, industry and regulatory authorities to evaluate and long-term predict the behaviour of the heat storage systems under consideration.

Project duration: 08/14–06/18

Funding organisation: BMWi

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Project partners:

  • Helmholtz Centre for Environmental Research – UFZ
  • Kiel University Christian Albrechts Universität zu Kiel (CAU)
  • SCHEER Heizsysteme & Produktionstechnik GmbH – coordinator

The research for this project was conducted in close cooperation with the Chair of Soil Mechanics and Foundation Engineering at the TU Bergakademie Freiberg.

At the UFZ, research for this project was also conducted at the Department Monitoring and Exploration Technologies.

At the Department of Environmental Informatics, research for this project was being conducted at the workgroup Geothermal Systems Analysis.

Project website: not available

This research was also part of the OpenGeoSys initiative (http://www.opengeosys.org/).

Final report: sent to the TIB Leibniz Information Centre for Science and Technology Hannover in February 2019, but not entered into the database of the TIB yet.