By Gary Thomas
A thermal storage system is currently being developed by scientists from the Fraunhofer Institute for Interfacial Engineering and Biotechnology in Stuttgart along with industrial partner ZeoSys in Berlin.
This system stores heat for longer time periods and can be used even at temperatures more that 100°C. Zeolites pellets are used in this new system. Zeolites are porous and offer a large surface area. Heat is generated when the pellets contact water vapor and the steam is bound within the pores through a physicochemical reaction. Energy is thus stored after the water is removed from the material. The capacity to adsorb water is what is actually stored and heat is released in the process. The term used to describe these kind of systems is sorptive thermal storage. In case the dried zeolite material can be kept away from contacting water, heat can be stored for an unlimited time period.
Mike Blicker, group manager of heat and sorption systems in the IGB stated that the researchers at first analyzed the implementation of the thermal storage principle and the locations where valves, heat exchangers and pumps need to be installed. The development partners of the institute were in charge of selecting appropriate zeolites and deciding on the size of the zeolite pellets. They also checked on the stability of the pellets after a number of storage cycles. The researchers have thus proved that heat can be stored and discharged in the thermal storage system without damaging the system.
Blicker stated that the final goal is to store heat in power plants utilized in residential and industrial buildings besides aiming to expand the usage of the thermal storage system and reducing its production cost.
The principles of the thermal storage system will be demonstrated by Fraunhofer researchers by using a model of this system. This demonstration will take place from 18 to 22 June at ACHEMA 2012 in Frankfurt.