IEA ES Annex 39: Large Thermal Energy Storages for District Heating

Large-scale heat storage systems will play a central role in increasing the necessary flexibility of district heating networks and enable the further expansion of renewable energies or the integration of waste heat in these systems. In order to overcome challenges in design, realization and operation of this technology and to enable its application in as many countries as possible, the Annex 39 "Large Water Heat Storage for District Heating Systems" was initiated.

The main objective of the Annex is to determine the aspects that are important in planning, decision-making and implementing large thermal energy storages for integration into district heating systems and for industrial processes, given the boundary conditions for different locations and different system configurations.

This will include the definition of representative application scenarios and the definition of dedicated storage concepts as well as the techno-economic evaluation of best practice examples.

Furthermore, the development, improvement and implementation of new material testing methods is targeted. In addition, the number of available simulation models for large thermal storages are rare and limited or they are not publicly available, as they have been developed for specific tasks in research projects. Therefore, the Annex aims to inventory and compare numerical simulation models of large thermal energy storages.

Due to existing synergies, four types of large-scale heat storage types are considered in the Annex:

• Pit Thermal Energy Storages (PTES)
• Tank Thermal Energy Storage (TTES)
• Aquifer Thermal Energy Storages (ATES)
• Borehole Thermal Energy Storages (BTES)

Austrian partners will play an important role in the consortium. Besides leading the Annex 39 as Operating Agent (AEE INTEWC), the participating Austrian institutes also contribute valuable knowledge and experience from completed and currently ongoing projects. In particular, Austrian institutes will actively collaborate on material related challenges for polymer liners (JKU Linz), the development of storage concepts and their evaluation (AIT, SOLID, AEE INTEC) as well as on aspects of the numerical simulation of large-scale heat storage systems (UIBK, AEE INTEC; AIT).

Envisaged results of Annex 39 are:

• Elaboration of application scenarios, storage concepts, key performance indicators, techno-economic assessments, and best practices;
• Development of new material testing procedures, water quality guidelines/recommendations, and a database of materials suitable for use in large-scale thermal storage;
• Inventory and comparison of numerical models, validation datasets, and recommendations for large-scale heat storage simulation;
• Tailored information materials (technically, economically, and environmentally relevant information) for relevant stakeholder groups.

The project results of Annex 39 and the emerging networks are to be transferred to the Austrian industries active in this field, in order to further improve their international market positions.

Moreover, dedicated results of the Annex are communicated to relevant national stakeholder groups to optimally initiate the implementation of this technology in Austria.

Austria (Operating Agent), Belgium, Canada, Switzerland, Germany, Denmark, Spain, France, Italy, Netherlands, Sweden, Turkey, United Kingdom

Project leader

Dr. Wim van Helden
AEE - Institut für Nachhaltige Technologien
Feldgasse 19, 8200 Gleisdorf
E-Mail: w.vanhelden@aee.at

Project partners

Dr.-Ing. Fabian Ochs
Technikerstraße 13, 5. Stock, Raum 515
E-Mail: fabian.ochs@uibk.ac.at

ao. Univ.-Prof. DI Dr.mont. Gernot M. WALLNER
Science Park 2 - 1st Floor - Room S2 122
E-Mail: gernot.wallner@jku.at

Dipl.-Ing. Paolo Leoni
AIT – Austrian Institute of Technology GmbH, Center for Energy
Giefinggasse 4, 1210 Wien
E-Mail: paolo.leoni@ait.ac.at

Maria Moser, MSc
SOLID SOLAR ENERGY SYSTEMS GMBH
Am Pfangberg 117, 8045 Graz
E-Mail: m.moser@solid.at