M. Bakker1*, W. G.J. van Helden1, and A. Hauer2

1 ECN, Energy Research Centre of the Netherlands, P. O. Box 1, 1755 ZG Petten, The Netherlands
2 ZAE Bayern, Walther-Meissner-Strasse 6, D-85748 Garching, Germany
Corresponding Author, m. bakker@ecn. nl

Abstract

A new IEA SHC/ECES Joint Task will be started on January 1, 2009. The objective of this new task, designated SHC Task 42 and ECES Annex 24, is to develop advanced materials for compact thermal energy storage, which can be used for renewable heating and cooling as well as for energy conservation. The task focuses on thermochemical materials, including sorption and composite materials, as well as on phase change materials, and includes work on material engineering and development, characterisation, numerical modelling, demonstration, and dissemination.

Keywords: thermal storage materials, renewable heating and cooling.

Background

Thermal energy storage is an important technology for renewable energy systems. By improving the effectiveness of thermal storage, the effectiveness of all renewable energy technologies that supply heat can be improved.

Particularly for solar thermal systems, thermal energy storage is essential. To reach high solar fractions, it is necessary to store heat (or cold) efficiently for longer periods of time. Until now, no cost-effective compact storage technologies are available to do this. For high solar fraction systems, hot water stores are expensive and require very large volumes of space. Alternative storage technologies, such as phase change materials (PCMs) and thermochemical materials (TCMs) are available on a laboratory scale. However, more research and development is needed before these technologies can be developed into commercial solutions.

In several IEA annexes, both ongoing and completed, it was concluded that materials are the main bottleneck for finding effective solutions for compact thermal energy storage, and that there is a need for new storage materials with a higher specific energy storage density and lower material cost.

Around the world, several groups are working on either thermal energy storage materials or applications. However, these activities are not sufficiently linked. The current activities are either limited to specific applications, or to specific materials. What is needed, and what can be provided by this new task, is a way to bring the ongoing work on materials and applications together.