Influence of interfaces on the thermal conductivity of metal hydride systems for heat storage applications

Rene Albert, Max-Planck-Institut für Kohleforschung, Mülheim an der Ruhr, Germany
Michael Felderhoff, Max-Planck-Institut für Kohleforschung, Mülheim an der Ruhr, Germany

Metal hydrides systems can be utilized not only for hydrogen storage but also for thermal energy storage (TES) applications. By using TES with f.i. solar technologies, heat can be stored from sun energy to be used later and therefore enables continuous power generation. Metal hydrides which are reversibly operating at temperatures >400°C are interesting for solar applications. A typical example for heat storage at high temperatures is the 2Mg/Fe system.

2 Mg + Fe + 3 H2 ⇌ Mg2FeH6

An important aspect for these systems is the heat and mass transfer in the metal hydride storage bed during the heat generation and absorption. The bed consists of different species with low (hydride compound) and high (metal compound) thermal conductivity. The microstructure of the particles, the surface itself and the oxygen amount on the surface are important for the thermal conductivity. Also the gas atmosphere and its pressure have an impact on the heat transfer of the storage system. Investigations on the effective thermal conductivity and the microstructure of the metal hydride systems will be done before and after cycling at >400°C and 100 bar.

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