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Energy has always been the driving force in the technological and economic development of societies. The consumption of a significant amount of energy is required to provide basic living conditions of developed countries (heating, transportation, lighting, etc.). Today's energy supply has a considerable impact on the environment, since it is fuelled by the burning of fossil fuels. In addition to this, the fossil fuel reserves are decreasing while the demand for energy is rapidly rising. Climate change, the depletion and geographical segregation of fossil fuel resources, health related issues as well as energy poverty constitute the driving forces towards the pursuit of alternative energy sources. In addition, countries with no access to oil reserves are being dependent from other countries for their energy supply, with a strong impact on politics and financial issues. But apart from occasional financial recessions, the long-term need for increasing amounts of energy as countries develop will become a major rate limiting step in the growth of the world economy [1]. The last years there is an on-going research on alternative fuels in order to overcome the fossil energy dependence and to provide a sustainable growth of economies and societies.In view of the above, countries that release the largest amounts of greenhouse gases to the atmosphere compared to the energy production are expected to minimise CO 2 emission and at the same time improve the share of ''clean'' energy in total energy consumption. The renewable, non-conventional energy sources, such as solar and wind energy, will remain available for infinite period. But due to the inherent nature of renewable energy resources being intermittent, there is a need to store any surplus electrical energy produced in order to be used during high energy

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A series of hydrogenated cubic C15 and hexagonal C14 ZrCr 2 Laves phases were studied by means of semiempirical extended Hu ¨ckel tight-binding, ab initio density functional theory methods and maximally localized Wannier functions, with a goal to find the most energetically favorable positions of interstitial H atoms in the host unit cells. We consider situations with one or two H atoms per primitive cell. Crystalorbital overlap population studies, performed for the C15 structure, show repulsion between two hydrogen atoms in close proximity. This is in accord with the ab initio calculations, performed for the hydrogenated C14 and C15 structures, which clearly favor two separated hydrogen atoms instead of the formation of moleculelike pairs in five-coordinated trigonal-bipyramidal environments.

SUMMARY A reliable process for compressing hydrogen and for removing all contaminants is that of the metal hydride thermal compression. The use of metal hydride technology in hydrogen compression applications, though, requires thorough structural characterization of the alloys and investigation of their sorption properties. The samples have been synthesized by induction – levitation melting and characterized by Rietveld analysis of the X‐ray diffraction patterns. Volumetric pressure–composition isotherm measurements have been conducted at 20, 60 and 90 °C, in order to investigate the maximum pressure that can be reached from the selected alloys using water of 90 °C. Experimental evidence shows that the maximum hydrogen uptake is low since all the alloys are consisted of Laves phases, but it is of minor importance if they have fast kinetics, given a constant volumetric hydrogen flow. Hysteresis is almost absent while all the alloys release nearly all the absorbed hydrogen during desorption. Due to hardware restrictions, the maximum hydrogen pressure for the measurements was limited at 100 bars. Practically, the maximum pressure that can be reached from the last alloy is more than 150 bars. Copyright © 2014 John Wiley & Sons, Ltd.

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Hydrogen as fuel has been a promising technology toward climate change mitigation efforts. To this end, in this paper we analyze the contribution of hydrogen technology to our future environmental goals. It is assumed that hydrogen is being produced in higher efficiency across time and this is simulated on Global Change Assessment Model (GCAM). The environmental restrictions applied are the expected emissions representative concentration pathways (RCP) 2.6, 4.5, and 6.0. Our results have shown increasing hydrogen production as the environmental constraints become stricter and hydrogen more efficient in being produced. This increase has been quantified and provided on open access as Supporting Information to this manuscript.