Metal hydrides storage

Chemical storage of hydrogen through absorption/desorption, which involves the chemical binding of atomic hydrogen within the structure of a solid material. Hydrogen release from metal hydrides can be achieved in two main ways, mostly via heating (thermolysis) or through reaction with water (hydrolysis). Storage materials should have certain characteristics such as rapid kinetics, good reversibility, high safety, affordable price and high storage capacity at moderate operating temperature and pressure. Metallic based hydrides can compress hydrogen based on their thermodynamic stability by using waste heat. It is expected as metal hydride compressor to supply high pressure hydrogen. Several metallic/metallic-based materials can absorb hydrogen with those characteristics, and hydrides of lightweight elements such as boron and aluminium and some transition metals, such as titanium and zirconium have shown potential for use as hydrogen storage materials. Metallic based hydrides suitable for hydrogen storage are elemental hydrides (e.g. MgH2), interstitial hydrides (e.g. LaNi5, TiFe) and complex metal hydrides (e.g. NaAlH4, LiBH4, NaBH4, Mg(BH4)2). Challenges associated with the use of hydrides are high weight and low hydrogen storage capacity for low-temperature hydrides and slow kinetics and high temperatures for relatively lighter hydrides. Latest research seeks to enhance hydrogen absorption/desorption kinetics at moderate temperatures and high storage capacity by adding catalysts, alloying with other elements and nano-structuring. Metal hydrides are good solutions for stationary use where the weight is not a problem and could also be used in some maritime applications. Furthermore, hydrogen storage in metal hydrides does not pose safety challenges, as it is stored at low pressure, use rather low temperatures and hydrogen is only released from the material when it is heated up.