IEA SHC Task 67: Compact Thermal Energy Storage Materials within Components within Systems

This Task aims to push forward the compact thermal energy storage (CTES) technology developments to accelerate their market introduction through the international collaboration of experts from materials research, components development and system integration. These technologies are based on the classes of phase change materials (PCM) and thermochemical materials (TCM). Materials from these classes will be studied, improved, characterized and tested in components.

Short Description

In order to reach the long-term climate goals, the transformation of the energy system, especially of the heating sector, is of decisive societal importance. The heating sector accounts for more than half of the Austrian energy consumption and is covered by more than 60% by fossil energy sources. Therefore, the energy transition and the increase of the renewable share is essential for achieving the climate and energy targets. One of the key technologies to achieve these goals are compact thermal energy storage technologies, as they enable the increased usage of waste heat, of solar energy (solar thermal and excess solar power from PV) and other renewable energy carriers in our energy system. They also increase the efficiency and availability of flexibility in the sectors of buildings, industry and power (sector coupling).


The main objectives of the Task are to 1) better understand the factors that influence the storage density and the performance degradation of CTES materials, 2) characterize these materials in a reliable and reproducible manner, 3) develop methods to effectively determine the State of Charge of a CTES, and 4) increase the knowledge base on how to design optimized heat exchangers and reactors for CTES technologies.
CTES technologies are based on the classes of phase change materials (PCM) and thermochemical materials (TCM). Materials from these classes will be studied, improved, characterized and tested in components. The main components for these technologies are heat exchangers and reactors which are also studied and further improved in the Task.


To achieve these objectives, the work is organized in 5 Subtasks:

Subtask A: Material Characterization and Database
Planned results: Several standardized measurement procedures for CTES materials were developed and validated and the materials database and knowledge database were further expanded and maintained.

Subtask B: CTES Material Improvement
Planned results: Proper strategies were identified that allow for tuning the reactivity of CTES materials thus improving their properties and final performances.

Subtask C: State of Charge – SoC Determination
Planned results: Techniques with which the SoC of a CTES can be determined in a reliable and cost-efficient way were identified.

Subtask D: Stability of PCM and TCM
Planned results: PCM and TCM with a predictable and improved stability were identified.

Subtask E: Effective Component Performance with Innovative Materials
Planned results: The material-component interaction was improved for an optimal system performance.

Subtask A is led by the AIT, which works on the development of standardized test methods for determining the viscosity and specific heat capacity of PCM and TCM and the optimization of these using round-robin tests. In Subtask B, the Institute for Applied Synthetic Chemistry at the Vienna University of Technology is developing a volume-stable copper sulfate by applying it to a carrier. AEE INTEC and FHOÖ participate in Subtask C by creating measurement techniques and experiments to determine the state of charge of the material. TU Vienna (Institute for Energy Technology and Thermodynamics), AEE INTEC and FHOÖ are developing fixed-bed and fluidized-bed reactors for sorption materials in Subtask E.


Australia, Austria (Operating Agent), Belgium, Canada, China, Denmark, Germany, Great Britain, Greece, France, India, Israel, Italy, Netherlands, Norway, Poland, Portugal, Slovenia, Spain, Sweden, Switzerland, Turkey, USA

Contact Address

Project leader

Dr. Wim van Helden
AEE – Institute for sustainable technologies
Feldgasse 19, 8200 Gleisdorf

Projekt partner

Dr. Daniel Lager
AIT – Austrian Institute of Technology Gmbh
Giefinggasse 4, 1210 Vienna

Dr. Peter Weinberger
TU Wien, Institut für angewandte Synthesechemie
Getreidemarkt 9/163, 1060 Viennna

Dr. Bernhard Zettl
FH Oberösterreich
Roseggerstraße 15, 4600 Wels

Dr. Andreas Werner
TU Wien, Institut für Energietechnik und Thermodynamik
Getreidemarkt 9/302, 1060 Vienna