Hydrogen storage challenges

The main reason for the growing interest in hydrogen economy is that the hydrogen economy may be a solution to the two main challenges facing the world now: the climate change and the need for security of energy supplies. Therefore the development of new, highly-efficient energy technologies that are either carbon-neutral or low emitting technologies is required. Further, the strong need for alternative fuels, especially in the transport sector, forced the research in this field. Hydrogen can be produced directly from sunlight and water by biological organisms, has a low environmental impact, with no emissions of greenhouse gases or other pollutants and therefore is ideal solution for transportation application. Anyhow, to make transition from present carbon based economy to hydrogen economy several problems has to be solved, regarding production, safety and storage. From all possible solutions for hydrogen storage (gas cylinders, liquid tank, solid state storage), the one which relies upon storage in solid media, such as hydride is the most attractive one. Solid-state storage implies hydrides such as metal/intermetallic and complex-chemical hydrides. Since the release of hydrogen from hydrides takes place via an endothermic process, this method of storage is the safest of all mention, but the problem of slow sorption process and high temperature of desorption has to solve if hydrogen will be used as an energy carrier. In the past two decades many studies were performed, either experimental or theoretical with the same subject - how to overcome these drawbacks. Sluggish thermodynamics and slow sorption/desorption kinetics can be altered by MgH2 destabilization - throughout surface modification and structural deformation. To improve the diffusivity of hydrogen in the metal hydride, various techniques such as ball milling and ion bombardment are applied, which in turn reduces the particle size, increases the defect concentration, and shortens the diffusion paths for hydrogen Also, sufficiently fast hydrogen sorption kinetics has been achieved by using metals, metal oxides, transition metal and transition metals oxides as additives in process of milling In this short review we have try to summarize some of the results of above mentioned methods of destabilization.