Development of a Compact Heat Storage System Based on Salt Hydrates

Abstract

Thermochemical reactions are one of the most promising means for compact, low loss and long term storage of solar heat in the built environment.The heat can be stored by making use of a reversible chemical reaction.In theory, an energy density 5-10 times higher than water can be reached.Additionally, no storage losses are associated with thermochemical heat storage.Thermochemical materials have been identified that are cheap, non-toxic, have sufficient energy density and have reaction temperatures that can be reached by a vacuum tube collector.These requirements are fulfilled by a number of salt hydrates.A detailed study at ECN identified MgCl 2 .6H 2 O as the most promising salt hydrate for compact seasonal heat storage.The material was found to be capable of storing and releasing heat under practical conditions.In the present paper, the results on MgCl 2 .6H 2 O characterization and the first results using a fixed bed reactor will be presented.