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Hydrogen offers a route to storing renewable electricity and lowering greenhouse gas emissions. Metal–organic framework (MOF) adsorbents are promising candidates for hydrogen storage, but a deep understanding of their potential for large-scale, stationary back-up power applications has been lacking. Here we utilize techno-economic analysis and process modelling, which leverage molecular simulation and experimental results, to evaluate the future opportunities of MOF-stored hydrogen for back-up power applications and set critical targets for future material development. We show that with carefully designed charging–discharging patterns, MOFs coupled with electrolysers and fuel cells are economically comparable with contemporary incumbent energy-storage technologies in back-up power applications. Future research should target developing MOFs with 15 g kg−1 of recoverable hydrogen adsorbed (excess uptake) and could be manufactured for under US$10 kg−1 to make the on-site storage system a leading option for back-up power applications.

Hydrogen offers a route to storing renewable electricity and lowering greenhouse gas emissions. Metal–organic framework (MOF) adsorbents are promising candidates for hydrogen storage, but a deep understanding of their potential for large-scale, stationary back-up power applications has been lacking. Here we utilize techno-economic analysis and process modelling, which leverage molecular simulation and experimental results, to evaluate the future opportunities of MOF-stored hydrogen for back-up power applications and set critical targets for future material development. We show that with carefully designed charging–discharging patterns, MOFs coupled with electrolysers and fuel cells are economically comparable with contemporary incumbent energy-storage technologies in back-up power applications. Future research should target developing MOFs with 15 g kg−1 of recoverable hydrogen adsorbed (excess uptake) and could be manufactured for under US$10 kg−1 to make the on-site storage system a leading option for back-up power applications.

Nanoporous adsorbents are a diverse category of solid-state materials that hold considerable promise for vehicular hydrogen storage. Although impressive storage capacities have been demonstrated for several materials, particularly at cryogenic temperatures, materials meeting all of the targets established by the U.S. Department of Energy have yet to be identified. In this Perspective, we provide an overview of the major known and proposed strategies for hydrogen adsorbents, with the aim of guiding ongoing research as well as future new storage concepts. The discussion of each strategy includes current relevant literature, strengths and weaknesses, and outstanding challenges that preclude implementation. We consider in particular metal-organic frameworks (MOFs), including surface area/volume tailoring, open metal sites, and the binding of multiple H2 molecules to a single metal site. Two related classes of porous framework materials, covalent organic frameworks (COFs) and porous aromatic frameworks (PAFs), are also discussed, as are graphene and graphene oxide and doped porous carbons. We additionally introduce criteria for evaluating the merits of a particular materials design strategy. Computation has become an important tool in the discovery of new storage materials, and a brief introduction to the benefits and limitations of computational predictions of H2 physisorption is therefore presented. Finally, considerations for the synthesis and characterization of hydrogen storage adsorbents are discussed.

Nanoporous adsorbents are a diverse category of solid-state materials that hold considerable promise for vehicular hydrogen storage. Although impressive storage capacities have been demonstrated for several materials, particularly at cryogenic temperatures, materials meeting all of the targets established by the U.S. Department of Energy have yet to be identified. In this Perspective, we provide an overview of the major known and proposed strategies for hydrogen adsorbents, with the aim of guiding ongoing research as well as future new storage concepts. The discussion of each strategy includes current relevant literature, strengths and weaknesses, and outstanding challenges that preclude implementation. We consider in particular metal-organic frameworks (MOFs), including surface area/volume tailoring, open metal sites, and the binding of multiple H2 molecules to a single metal site. Two related classes of porous framework materials, covalent organic frameworks (COFs) and porous aromatic frameworks (PAFs), are also discussed, as are graphene and graphene oxide and doped porous carbons. We additionally introduce criteria for evaluating the merits of a particular materials design strategy. Computation has become an important tool in the discovery of new storage materials, and a brief introduction to the benefits and limitations of computational predictions of H2 physisorption is therefore presented. Finally, considerations for the synthesis and characterization of hydrogen storage adsorbents are discussed.

© 2016, Springer-Verlag Berlin Heidelberg.The research on complex hydrides for hydrogen storage was initiated by the discovery of Ti as a hydrogen sorption catalyst in NaAlH4 by Boris Bogdanovic in 1996. A large number of new complex hydride materials in various forms and combinations have been synthesized and characterized, and the knowledge regarding the properties of complex hydrides and the synthesis methods has grown enormously since then. A significant portion of the research groups active in the field of complex hydrides is collaborators in the International Energy Agreement Task 32. This paper reports about the important issues in the field of complex hydride research, i.e. the synthesis of borohydrides, the thermodynamics of complex hydrides, the effects of size and confinement, the hydrogen sorption mechanism and the complex hydride composites as well as the properties of liquid complex hydrides. This paper is the result of the collaboration of several groups and is an excellent summary of the recent achievements.