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[en] Hydrogen storage system development is a key enabling technology for the widespread introduction of hydrogen fuel cells. We have developed novel liquid-phase materials that undergo catalytic hydrogenation at the hydrogen production location, and are readily de-hydrogenated at the point of use. This material-based hydrogen storage approach provides a liquid fuel paradigm where the consumer and other participants within the supply chain never come into contact with gaseous or liquid hydrogen. In addition to removing hydrogen from the supply chain, this approach provides the opportunity to build on the current liquid fuel infrastructure for a smooth fuel transition. Technical details of the approach, additional advantages over other hydrogen storage technologies, and remaining challenges will be covered. (authors)
[en] Once every five years, the U.S. Department of Energy (DOE) requires that each of its Standards and Handbooks undergo a maintenance review (also known as 'sunset reviews'). There are 3 possible outcomes of a maintenance review: 1) reaffirmation as current, accurate, and of continuing value to the Department; 2) revision to be current, accurate, and of continuing value; or 3) cancellation. DOE-HDBK-1129-2008, Tritium Handling and Safe Storage, is following option 2) above; the required justification of continuing value was demonstrated by a lack of comparable technical breadth and depth available in other publications. This paper gives an overview of the updates that the Tritium Handling and Safe Storage Guide will undergo. It is expected that the update will be completed in early 2014. (authors)
[en] Highlights: • The orbitals populations of torus-type C120 are changed by substituted group. • The accumulate fields of H2 are changed by metal or nonmetal modifications. • The hydrogen storage capacity of torus-type Li-C120 is enhanced by Li. • The molecular frontier orbitals influence hydrogen storage properties of Li-C120. The hydrogen adsorption properties for the torus-type C120, and the changes of adsorption influenced by nonmetal and metal have been systematically investigated. The results show that, in the pristine torus-type C120, the inner carbon atoms have more negative static potential than the outer ones. H2 intends to accumulate at the area near inner carbon atoms. However, torus-type C120 is modified by nonmetal (N and O) or metal (Li), the accumulated fields of H2 are changed. Li can evidently enhance the hydrogen storage capacity. The most gravimetric density is predicted to be 7.21 wt% for the 8Li-C120 in 77 K and 1200 kPa.
[en] The hydrogen storage properties of pure Mg are investigated at 573 K under 12 bar H2. In addition, in order to increase the hydriding and dehydriding rates of pure Mg, it is ground under hydrogen (reactive mechanical grinding, RMG), and its hydrogen storage properties are investigated. The pure Mg absorbs hydrogen very slowly. At n = 1, the pure Mg absorbs 0.05 wt.% H for 5 min, 0.08 wt.% H for 10 min, and 0.29 wt.% H for 60 min at 573 K under 12 bar H2. The hydriding rate decreases as the number of cycles increases from n = 7. At n = 7, the pure Mg absorbs 0.96 wt.% H for 5 min, 1.29 wt.% H for 10 min, and 2.20 wt.% H for 60 min. At n = 1, the pure Mg after RMG does not absorb hydrogen. The hydriding rate of pure Mg after RMG increases as the number of cycles increases from n = 1 to n = 11. The pure Mg after RMG absorbs 1.91 wt.% H for 5 min, 2.61 wt.% H for 10 min, and 3.65 wt.% H for 60 min at n = 11. The reactive mechanical grinding of the pure Mg and the hydriding-dehydriding cycling of the pure Mg after RMG are believed to create defects on the surface and in the interior of Mg particles and to form cracks in Mg particles.
[en] Hydrogen is now one of the potential vectors of energy for the future. To overcome the problems of hydrogen storage, many works are focused towards the development of new materials. In this paper, new composite materials Mg metal catalysts (Ni or Pd) are synthesized with an original route, the chemical fluid deposition process in supercritical fluids. The two studied materials (Mg-Ni and Mg-Pd) show the potentiality of the CFD route in supercritical fluids to decor surfaces with a structuration from the micrometer scale down to the nanometer one. Regarding hydrogen sorption, the catalytic effect of Ni is higher than the one of palladium. The cyclability is hugely improved with 'SCF materials' in comparison with ball milling ones because the catalysts stay always on the magnesium particle surface. (authors)
[en] Although hydrogen is one of the most efficient fuel per unit of mass, its low density per unit volume requires high pressure gaseous storage or cyrogenic storage in liquid form for practical applications. A promising technique to reduce the pressure requirements for gaseous storage is to use the adsorption properties of carbon materials. However, physisorption of hydrogen on activated carbon requires operating temperatures of the order of 77K and a proper densification of the carbon to exhibit appreciable gains over compression. Large absorbed densities of hydrogen have been reported on carbon nanostructures such as nanotubes and nanofibers, at or near room temperature. Adsorption storage of hydrogen using such carbon materials may therefore be possible at much higher temperatures than activated carbon. The precise mechanisms that could explain the large adsorbed densities is still not understood. Although physiosorption does not appear to be sufficient to explain by itself the large reported values of the adsorption density of nanotubes and nanofibers, it is interesting to study its contribution to the absorbed density and to compare it to other carbon structures such as activated carbon, particularly in view of the controversy surrounding the actual values of the absorbed density in carbon nanostructures. In this work, we will study the adsorption isotherms of hydrogen on caped and uncaped carbon nanotubes and nanotube ropes in the limit of Henry's Law by calculating the second virial coefficient for gas solid interaction and compare them to layered carbon structures
[en] The possibilities of hydrogen storage using borohydrides are presented and discussed specially in regard of the recoverable hydrogen amount and related to the recovering conditions. A rapid analysis of storage possibilities is proposed taking in account the two main ways for hydrogen evolution: the dehydrogenation obtained through thermal decomposition or the hydrolysis of solids or solutions. The recoverable hydrogen is related to the dehydrogenation conditions and the real hydrogen useful percentage is determined for each case of use. The high temperature required for dehydrogenation even when using catalyzed compounds lead to poor outlooks for this storage way. The hydrolysis conditions direct the chemical yield of the water consuming, and this must be related to the experimental conditions which rule the storage capacity of the 'fuel' derived from the borohydride. (authors)
[en] Highlights: • First principles is employed to study the structure of K2B12H12. • Predict the thermodynamic reversible hydrogen reactions in the KBH4/M(M = Li, Na, Ca)(BH4)n(n = 1,2) system. • Predict two new hydrogen storage reactions involving KBH4 for on-board hydrogen storage. - Abstract: Potassium borohydrides [KBH4] is an attractive candidate for on-board storage because it contains high densities of hydrogen by weight and volume. Using a set of recently developed theoretical first-principles methods, we predict hydrogen storage reactions in the K-M(Li, Na, Ca)-B-H system. Hydrogen release from KBH4 is predicted to proceed via intermediate K2B12H12 phase. In the present study, we predict two new hydrogen storage reactions that are some of the most attractive among the presently known ones. They are predicted to have thermodynamics for hydrogen release within the target window for on-board storage being actively considered for hydrogen storage applications
[en] The possibilities of hydrogen storage using borohydrides are presented and discussed specially in regard to the recoverable hydrogen amount and to the recovery conditions. A rapid analysis of storage possibilities is proposed taking in account the two main ways for hydrogen evolution: the thermolysis of borohydrides or the hydrolysis of solid or dissolved borohydrides. The recoverable hydrogen is related to the dehydrogenation conditions and the real hydrogen useful percentage is determined for each case of use. (authors)
[en] In the present study, hydrogen absorption experiments using Zr(zirconium) and Ti(titanium) in the form of metal sponge, strip and rod were carried out to investigate the hydrogen absorption characteristics with reaction temperature, the type of metal, activation conditions, and the presence of helium in hydrogen. Zr and Ti sponges showed a high hydrogen absorption capacity inspite of a low reaction temperature. The H/M which indicates the capacity of hydrogen absorption, was measured at 2.0 for the Zr/Ti sponge under experimental condition of 25 .deg. C. However, in the case of the Zr/Ti strip and rod, the hydrogen absorption capacity was very low at 25 .deg. C