• The Transactions of the Korean Institute of Electrical Engineers P
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• v.67 no.2
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• pp.94-99
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• 2018

Depending on how the energy storage system(ESS) is used in a system that can construct a microgrid by using an independent power source such as campus, surplus power can be generated that can not be charged to the ESS. For example, assuming that heat is supplied by a fuel cell in the case of a system in which thermal self-sustaining is prioritized, the fuel cell capacity required differs depending on the heat load. The amount of surplus power that can not be stored in the ESS will appear differently depending on the load operation of the fuel cell for each cycle. This power is hydrogenated through a water electrolytic device to present the amount of hydrogen energy that can be operated for each cycle. Therefore, this paper propose the possibility of utilizing University campus as a hydrogen station.

• Journal of Hydrogen and New Energy
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• v.16 no.2
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• pp.122-129
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• 2005

The characteristics of hydrogen storage have been investigated in the Ti-Cr-Mo and Ti-Cr-V ternary alloys with bcc structure. The alloys were melted by arc furnace and remelted 4-5 times for homogeneity. The lattice parameters, microstructures and phases of the alloys were examined by SEM, EDX and XRD, and the Pressure-Composition isotherms of the alloys were measured. From these data the relationship of the maximum and effective hydrogen storage capacities vs. chemical composition, lattice parameter and the radius of tetrahedral site were analyzed and discussed. The results showed that all of these alloy, in the range of the this study, had mainly bcc solid solutions with small amount of Ti segregation due to a lower melting point of Ti compared with other elements. Lattice parameters of the alloys were very near to the atomic average values of lattice parameters of the constituent elements. It was also found that maximum hydrogen storage capacities of the Ti-Cr-Mo alloys increased with increasing Ti content and the radius of tetrahedral site but the effective hydrogen storage capacities decreased after showing the maximum. The hydrogen storage capacities of the Ti-Cr-V alloys were almost same even though the V contens were quite different from alloy to alloy and this could be attributed to the almost same Ti/Cr ratio of the alloys. The maximum effective hydrogen storage capacity of the Ti-Cr-Mo alloys was revealed at Ti content of about 40${\sim}$50 at% and radius of tetrahedral site of 0.43${\sim}$0.45 nm. The Ti-Cr-V alloys showed the hydrogen storage capacities of 3.0 wt% and effective hydrogen storage capacities of 1.5 wt%.

• Journal of Hydrogen and New Energy
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• v.9 no.1
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• pp.31-37
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• 1998

The crystal structures, the lattice parameters and the characteristics of hydrogen storage at 303K has been investigated in the ternary alloys of Ti-Cr-V system. All of these alloys, in the range of this study, have shown a bcc structure. The hydrogen storage capacities and the effective hydrogen storage capacities of the alloys were strongly dependant on the composition ratio of Ti/Cr, showing their maximum values at the Ti/Cr ratio of about 0.75. It was also found that the lattice parameters of the alloys increased linearly with an increase of the Ti/Cr ratio. The differences in affinities to hydrogen and lattice parameters of pure metal states of the three elements have been adopted in oder to explain the Ti/Cr ratio dependance of the lattice parameter and hydrogen storage capacity of the alloys.

• Journal of Hydrogen and New Energy
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• v.33 no.2
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• pp.148-157
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• 2022

Research on hydrogen storage is active to properly deal with hydrogen, which is considered a next-generation energy medium. In particular, research on metal hydride with excellent safety and energy efficiency has attracted attention, and among them, magnesium-based hydrogen storage alloys have been studied for a long time due to their high storage density, low cost, and abundance. However, Mg-based alloys require high temperature conditions due to strong binding enthalpy, and have many difficulties due to slow hydrogenation kinetics and reduction in hydrogen storage capacity due to oxidation, and various strategies have been proposed for this. This research manufactured Mg₂Ni to improve hydrogenation kinetics and synthesize about 5, 10, 20 wt% of CaF₂ as a catalyst for controlling oxidation. Mg₂NiHx-CaF₂ produced by hydrogen induced mechanical alloying analyzed hydrogenation kinetics through an automatic PCT measurement system under conditions of 423 K, 523 K, and 623 K. In addition, material life cycle assessment was conducted through Gabi software and CML 2001 and Eco-Indicator 99' methodology, and the environmental impact characteristics of the manufacturing process of the composites were analyzed. In conclusion, it was found that the effects of resource depletion (ARD) and fossil fuels had a higher burden than other impact categories.

• Journal of Hydrogen and New Energy
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• v.8 no.2
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• pp.51-56
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• 1997

The Zr-based Laves phase, $ZrV_2$ hydrogen storage alloy is not suited for the electrode of Ni-MH battery, because the binding strength of that with hydrogen is too strong although the storage capacity is high. For an application to electrode a part of V in alloys is substituted with Ni to make weaken the binding strength. The electrochemical and thermodynamic properties of Zr-V-Ni system alloys are investigated from the equilibrium potential and studied the possibility for the application to the rechargeable battery electrode.

• Journal of Hydrogen and New Energy
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• v.17 no.4
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• pp.389-394
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• 2006

Mg and Mg-based alloys are promising hydrogen storage alloys for renewable clean energy applications. It is a lightweight and low cost material with high hydrogen storage capacity. However, commercial applications of the Mg hydride are currently hindered by its high absorption/desorption temperature, and very slow reaction kinetics. In this work, we aim to study the absorption properties of the $Mg_2Ni$-5mass% Nb composite prepared by mechanical alloying under hydrogen. The absorption capacity of the sample is found to be about 3.0 wt.% at T=573 K and P=1.0 MPa. The absorption characteristics observed have been compared with those of the prepared $Mg_2Ni$.

• Journal of Hydrogen and New Energy
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• v.10 no.4
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• pp.197-210
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• 1999

The hydrogen storage performance and electrochemical properties of $Zr_{1-X}Ti_X(Mn_{0.2}V_{0.2}Ni_{0.6})_{1.8}$(X=0.0, 0.2, 0.4, 0.6) alloys are investigated. The relationship between discharge performance and alloy characteristics such as P-C-T characteristics and crystallographic parameters is also discussed. All of these alloys are found to have mainly a C14-type Laves phase structure by X-ray diffraction analysis. As the mole fraction of Ti in the alloy increases, the reversible hydrogen storage capacity decreases while the equilibrium hydrogen pressure of alloy increases. Furthermore, the discharge capacity shows a maxima behavior and the rate-capability is increased, but the cycling durability is rapidly degraded with increasing Ti content in the alloy. In order to analyze the above phenomena, the phase distribution, surface composition, and dissolution amount of alloy constituting elements are examined by S.E.M., A.E.S. and I.C.P. respectively. The decrease of secondary phase amount with increasing Ti content in the alloy explains that the micro-galvanic corrosion by multiphase formation is little related with the degradation of the alloys. The analysis of surface composition shows that the rapid degradation of Ti-substituted Zr base alloy electrode is due to the growth of oxygen penetration layer. After comparing the radii of atoms and ions in the electrolyte, it is clear that the electrode surface becomes more porous, and that is the source of growth of oxygen penetration layer while accelerating the dissolution of alloy constituting elements with increasing Ti content. Consequently, the rapid degradation (fast growth of the oxygen-penetrated layer) with increasing Ti substitution in Zr-based alloy is ascribed to the formation of porous surface oxide through which the oxygen atom and hydroxyl ion with relatively large radius can easily transport into the electrode surface.

• Journal of Hydrogen and New Energy
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• v.27 no.4
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• pp.349-356
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• 2016

Volumetric capacity metrics at cryogenic condition are critical for technological and commercial development. It must be calculated and reported in a uniform and consistent manner to allow comparisons among different materials. In this paper, we propose a simple and universal protocol for the determination of volumetric capacity of sorbent materials at cryogenic condition. Usually, the sample container volume containing porous sample at RT can be directly determined by a helium expansion test. At cryogenic temperatures, however, this direct helium expansion test results in inaccurate values of the sample container volume for microporous materials due to a significant helium adsorption, resulting significant errors in hydrogen uptake. For reducing this container volume error, therefore, we introduced and applied the indirect method such as 'volume correction using a non-porous material', showing a reliable cold volume correction.

• Journal of Hydrogen and New Energy
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• v.8 no.1
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• pp.11-21
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• 1997

$ZrV_{0.7}Mn_{0.5}Ni_{1.2}$ alloy is attractive for anode material in Ni/MH secondary battery because of its large hydrogen storage capacity in gas-solid reaction and long cycling durability in KOH electrolyte. In this work, in order to further improve the discharge performance of this alloy electrode, the alloy was annealed by optimal condition which is for 12 hours at $1000^{\circ}C$. The alloy annealed under optimal condition had higher rate capability and discharge capacity than as-cast one. The microstructure of the as-cast and annealed alloy was investigated by scanning electron microscopy and energy dispersive spectroscopy. Ni content in the matrix was increased, being this homogenized after annealing. Additionally, The measurement of the surface area by B.E.T. analysis showed that there was little difference as-cast and annealed alloy. Therefore, improvement in the rate capability of the annealed alloy is due to increase of Ni content in the matrix.

• Journal of Hydrogen and New Energy
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• v.16 no.3
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• pp.238-243
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• 2005

Mg and Mg-based alloys are most important hydrogen storage materials. It is a lightweight and low-cost materials with high hydrogen storage capacity. However, the formation of hydride at high temperature, the deterioration effect, the hydriding and dehydriding kinetics are bad factor for application. In this study, Mg and Ni have been produced by hydrogen induced mechanical alloying(HIMA) process. The raw materials, Mg(purity 99.9%) chip and Ni(purity 99.95%) chip was prepared by using a planetary ball mill apparatus(FRITSCH pulverisette 5). The balls to chips mass ratio(BCR) are 30:1. The hydrogen pressure induced 2.0MPa and milling times were 12, 24, 48, 72, 96 hours with a rotating speed of 200rpm. X-ray diffraction(XRD) analysis was made to characterize the crystallite size and misfit strain. The crystallite size measured by laser particle size analysis(PSA). Microstructure changes were investigated by scanning electron microscopy(SEM) and the transmission electron microscopy(TEM). The hydrogen storage properties were evaluated by using an Sivert's type automatic pressure-composition-therm(PCT) apparatus.