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Recently, the industrial and public interest in hydrogen technologies has strongly risen, since hydrogen is the ideal means for medium to long term energy storage, transport and usage in combination with renewable and green energy supply. Therefore, in a future energy system the production, storage and usage of green hydrogen is a key technology. Hydrogen is and will in future be even more used for industrial production processes as reduction agent or for the production of synthetic hydrocarbons, especially in the chemical industry and refineries. Under certain conditions material based systems for hydrogen storage and compression offer advantages over the classical systems based on gaseous or liquid hydrogen. This includes in particular lower maintenance costs, higher reliability and safety. Hydrogen storage is possible at pressures and temperatures much closer to ambient conditions. Hydrogen compression is possible without any moving parts and only by using waste heat. In this paper, the newest developments of hydrogen carriers for storage and compression are summarized. In addition, an overview of the different research activities in this field are given.

A newly developed composite material has been explored based on metal hydrides in combination with polymers enriched with highly porous carbon. As metal hydride, a RHC (reactive hydride composite) was chosen (e.g., MgH2 + 2 LiBH4). The hydride is infiltrated into the pores of the porous carbon suppressing the long-range phase separation of the two different hydrides by nano-confinement. The aim is to maintain fast kinetics and achieve cycle stability of the RHC (reactive hydride composite). The combination of RHC and porous carbon is then integrated into a polymer film to allow an easy and safe handling of the material. To produce a storage system out of such a film, the thin material is rolled in the same style like a rolled membrane module; i.e., it is rolled together with a thin spacer (e.g., steel mesh) allowing an easy hydrogen access to all parts of the membrane. The last step is the implementation of the rolled storage module into the tank shell. To analyze different design concepts and the behavior of this newly developed composite storage material, extensive FEM-simulations have been realized for different cooling structures. The latter is necessary to fulfil the thermodynamic requirements and to maximize the speed of hydrogen storage. Therefore, the temperature development within the storage during hydrogen feeding are investigated. Beside this, the hydrogen flow as well as the kinetics of the chemical reaction are analyzed. Based on such extensive simulations of different design concepts, the most promising overall storage systems are developed and systematically optimized. Finally, the total hydrogen content of the overall storage system is calculated and compared between different design concepts. Based on this, conclusions are drawn about robust criteria how to construct a cooling and heating device for this new storage material.

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