Hydrogen Storage

AbstractÐThe electrochemical compression of hydrogen is well known since years. But new developments of the polymer electrolyte membrane (PEM) fuel cells make it possible to realize the electrochemical compression in a PEM-cell with high eciency. A new cell design of PEM-cells for operation with a high pressure dierence between anode side and cathode side was developed. The puri®cation of hydrogen from carbon monoxide of the reformer gas can be integrated in the hydrogen compressor cell. Operation parameters are presented. #

We have recently highlighted that H-SSZ-13, a highly siliceous zeolite (Si/Al ¼ 11.6) with a chabazitic framework, is the most efficient zeolitic material for hydrogen storage [A. Zecchina, S. Bordiga, J. G. Vitillo, G. Ricchiardi, C. Lamberti, G. Spoto, M. Bjørgen and K. P. Lillerud, J. Am. Chem. Soc., 2005, 127, 6361]. The aim of this new study is thus to clarify both the role played by the acidic strength and by the density of the polarizing centers hosted in the same framework topology in the increase of the adsorptive capabilities of the chabazitic materials towards H 2 . To achieve this goal, the volumetric experiments of H 2 uptake (performed at 77 K) and the transmission IR experiment of H 2 adsorption at 15 K have been performed on H-SSZ-13, H-SAPO-34 (the isostructural silico-aluminophosphate material with the same Brønsted site density) and H-CHA (the standard chabazite zeolite: Si/Al ¼ 2.1) materials. We have found that a H 2 uptake improvement has been obtained by increasing the acidic strength of the Brønsted sites (moving from H-SAPO-34 to H-SSZ-13). Conversely, the important increase of the Brønsted sites density (moving from H-SSZ-13 to H-CHA) has played a negative role. This unexpected behavior has been explained as follows. The additional Brønsted sites are in mutual interaction via H-bonds inside the small cages of the chabazitic framework and for most of them the energetic cost needed to displace the adjacent OH ligand is higher than the adsorption enthalpy of the OHÁ Á ÁH 2 adduct. From our work it can be concluded that proton exchanged chabazitic frameworks represent, among zeolites, the most efficient materials for hydrogen storage. We have shown that a proper balance between available space (volume accessible to hydrogen), high contact surface, and specific interaction with strong and isolated polarizing centers are the necessary characteristics requested to design better materials for molecular H 2 storage. R E S E A R C H P A P E R PCCP www.rsc.org/pccp

This paper deals with enhancement of hydrogen storage capacity for AB5 type alloy MmNi4:6Fe0:4 from ∼ 1:5 to ∼ 2:04 wt%. It has been shown that through suitable processing involving ball milling with speciÿc parameters (200 rpm, 20 min), the alloy particles besides getting fractured to smaller particles also become strained. The maximum strain, increase in lattice constant and unit cell volume are achieved for ball milling parameters of ∼ 200 rpm and 20 min. It has been suggested that the increase in the unit cell volume results in increase of interstitial hole sizes. This induces higher number of interstitials in unit cell of the material MmNi4:6Fe0:4 to be occupied by hydrogen atoms resulting in increase of hydrogen storage capacity from its value of ∼ 1:5 wt% obtained in the as-synthesized material to ∼ 2:04 wt% for ball-milled materials which embody strained particles. ?

Since 1990, there has been an ongoing collaboration among the authors in the three laboratories to (1) prepare alloys of the AB(sub 5) and AB(sub 2) types, using arc-melting/annealing and mechanical alloying/annealing techniques; (2) examine their physico-chemical characteristics (morphology, composition); (3) determine the hydrogen absorption/desorption behavior (pressure-composition isotherms as a function of temperature); and (4) evaluate their performance characteristics as hydride electrodes (charge/discharge, capacity retention, cycle life, high rate capability). The work carried out on representative AB(sub 5) and AB(sub 2) type modified alloys (by partial substitution or with small additives of other elements) is presented. The purpose of the modification was to optimize the thermodynamics and kinetics of the hydriding/dehydriding reactions and enhance the stabilities of the alloys for the desired battery applications. The results of our collaboration, to date, demonstrate that (1) alloys prepared by arc melting/annealing and mechanical alloying/annealing techniques exhibit similar morphology, composition and hydriding/dehydriding characteristics; (2) alloys with the appropriate small amounts of substituent or additive elements: (1) retain the single phase structure, (2) improve the hydriding/dehydriding reactions for the battery applications, and (3) enhance the stability in the battery environment; and (3) the AB(sub 2) type alloys exhibit higher energy densities than the AB(sub 5) type alloys but the state-of-the-art, commercialized batteries are predominantly manufactured using Ab(sub 5) type alloys.

The notion of dominant designs deals with dominance in the market and the dominant design is thought to be dominant because of market selection forces. The notion thus ignores the possible selection that takes place in pre-market R&D stages of technological trajectories. In this paper we ask the question whether pre-market selection takes place and if this can lead to

This paper discusses the possibility of extraction of Hydrogen from urine and using it as a fuel to power various machinery and automobiles which could run on hydrogen fuel. The paper also attempts to show a practical layout of various processes and stages which could facilitate the conversion of urea into hydrogen molecules which can be then stored in compressed chambers and subsequently distributed as required. The design is compact, user-friendly, sustainable and is mostly based on domestic use.

A new dipolar binary liquid strategy has been developed to manganese oxide nanostructure's synthesis, in which different manganese oxide nanostructures have been easily obtained without using any templates or catalysts. It has been found that the reaction temperatures, alkali precipitators' concentrations and Mn 2þ concentrations play a significant role in our dipolar binary liquid technique. This novel approach can be potentially extended to fabricate 1D nanostructures of other anisotropic materials with interesting morphologies free of any surfactants. In addition, the research of products' electrochemical properties has demonstrated that manganese oxide nanomaterials maybe potentially applied as a material for electrochemical hydrogen storage.

The hydrogen storage alloy electrodes of the type Ti4Ni2Oy (y = 0, 0.3 and 0.6) and Ti3.5Zro.5Ni2Oy (y = 0.15 and 0.3) were investigated by impedance spectroscopy for potential application as negative electrode in alkaline secondary nickel-metal hydride (MH) batteries. The phase Ti4Ni200.30 was found to be electrochemically more stable during the cycling. The addition of copper or nickel powder as current collector improved the electrochemical behavior of the electrodes. It was possible in this way to decrease the charge transfer resistance. These additions have a negligible influence on the stability of electrode material during cycling.

This paper gives an overview of the opportunities that exist for the combination of stochastic power generation and hydrogen production, storage and end-use. It is described how hydrogen storage can be applied in both isolated and grid-connected systems, and how the produced hydrogen can be utilized for stationary energy supply and as a fuel for transportation. The paper discusses the benefits and limitations of the different hydrogen storage applications, and emphasizes the need for stochastic studies both for long-term planning and operation planning. A simulation case study of using excess wind power in a weak grid to produce hydrogen for vehicles has been presented. It is shown that the penetration of wind power can be significantly increased by introducing electrolytic hydrogen production as a controllable load

Modern photovoltaic systems wholesaling on Chinese marketplaces such as Alibaba sell for as little as $0.18/watt from RISEN ENERGY CO., LTD for monocrystalline architecture. Degradation rates are typically around 15% for 20 years, or around 0.8% per anum. That means a 1 kW system will produce 84% of its original power output after two decades. Panel type: 275-280/330-335W Multi-Module Price per watt (USD): 0.28 High, 0.175 Low, 0.185 Average. The average price for 350-watt panels is 18.5 cents per watt. The second major cost input is the DC/AC converter. Using data from Alibaba, numerous products were sampled. The most cost-competitive DC/AC rectifiers were ones used for solar-powered well water pumps. 7.5 kW units were priced around $250, yielding a price per kilowatt of $34. In our case, we only need a DC-DC converter, stepping down the voltage from the panel peak of around 35 to 12 for the electrolyzer. DC/DC converters are roughly the same price as DC/AC inverters. The Levelized Cost of Energy (LCOE) is determined by the irradiance available much more so than it is by slight differences in the panel module costs. A solar array in Scotland (880 kWh/kWp/yr) won't be nearly as cheap as one in Chile (2300 kWh/kWp/yr), or in Los Vegas (1900 kWh/kWp/yr). With the availability of low-cost photovoltaic energy without the need for balancing grid requirements, the need for storage is eliminated, this opens up the possibility of producing ultra-low cost hydrogen below the price of methane reforming. Hydrogen on its own is virtually useless, it has virtually no application as a fuel, thus we are forced to turn to ammonia. Until ammonia begins its use as a low-emission fuel in the near future, the fertilizer market is the biggest opportunity for disruption. Rather than purchasing

Battery graphite rod was modified with Ni nanoparticles with a new electroless procedure and the performance of the proposed electrode was evaluated as a non-enzymatic anode for electrocatalytic oxidation of glucose in alkaline media. Glucose fuel cells that use enzymes or microorganisms catalysts are limited by their extremely low power output and rather short durability. The structure and morphology of the electrode surface were examined with X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX) and scanning electron microscopy (SEM) techniques. Voltammetric and amperometric studies indicated that the onset potential of the glucose oxidation is low (~ 0.3 V) and the electrode stability is good. In addition to these advantageous, due to easily preparation and low cost, it will be used probably in glucose fuel cells as an anode.

The lattice constants a and c of the as cast hexagonal (C14) Laves phase TiCr1.78-xMnx (x=0, 0.4, 0.6 and 0.8) have been measured by X-ray diffraction at room temperature as a function of the Mn content. It has been found that a decreases with increasing x while c remains almost unchanged. Being this alloy interesting as material for solid state hydrogen storage, pressure-composition isotherms have been traced on desorption mode for the H2 gas pressure and temperature varying from 10 to 0.01 MPa and from 209 to 307 K, respectively. From the temperature dependence of the plateau pressure the molar quantities ΔH and ΔS associated with the hydride decomposition have been determined as a function of the Mn content. With increasing x, both ΔH and ΔS progressively decrease, and the desorption pressure initially decreases (for x ≤ 0.4) then slightly increases. At the same time, the pseudo-plateaus become flatter.

The feasibility of combined metal hydride compressor and heat pump "MHCHP# has been studied through charac! terising of various synthesised and commercial alloys[ The operation of a two!stage metal hydride compressor has been demonstrated] hydrogen pressure was increased from 01Ð07 bar up to 74Ð009 bar by utilising very narrow temperature interval "19Ð59>C#[ By adding a third alloy\ TiCrMn 9[44 Fe 9[29 V 9[04 \ the hydrogen pressure close to 199 bar could be achieved[ The heat pump cycle was also demonstrated by using the same alloys as in the two!stage compressor[ A MHCHP would be very useful for self!su.cient solar energy systems] for example in a PV!hydrogen system\ a three! stage compressor can increase the storage pressure of hydrogen from 29 bar up to 199 bar\ and the heat pump can reduce the power of photovoltaics and the size of the hydrogen storage by more than 09)[ Þ 0888 International Association for Hydrogen Energy[ Published by Elsevier Science Ltd[ All rights reserved[

The article gives a comprehensive overview of hydrogen storage in carbon nanostructures, including experimental results and theoretical calculations. Soon after the discovery of carbon nanotubes in 1991, different research groups succeeded in filling carbon nanotubes with some elements, and, therefore, the question arose of filling carbon nanotubes with hydrogen by possibly using new effects such as nano-capillarity. Subsequently, very promising experiments claiming high hydrogen storage capacities in different carbon nanostructures initiated enormous research activity. Hydrogen storage capacities have been reported that exceed the benchmark for automotive application of 6.5 wt% set by the U.S. Department of Energy. However, the experimental data obtained with different methods for various carbon nanostructures show an extreme scatter. Classical calculations based on physisorption of hydrogen molecules could not explain the high storage capacities measured at ambient temperature, and, assuming chemisorption of hydrogen atoms, hydrogen release requires temperatures too high for technical applications. Up to now, only a few calculations and experiments indicate the possibility of an intermediate binding energy. Recently, serious doubt has arisen in relation to several key experiments, causing considerable controversy. Furthermore, high hydrogen storage capacities measured for carbon nanofibers did not survive cross-checking in different laboratories. Therefore, in light of today's knowledge, it is becoming less likely that at moderate pressures around room temperature carbon nanostructures can store the amount of hydrogen required for automotive applications.

Mg 2 Ni-type alloys, i.e., Mg 2 Ni, Mg 2 Ni 0.75 Cu 0.25 , Mg 2 Ni 0.6 Cu 0.4 and Mg 2 Ni 0.75 V 0.25 were synthesized by mechanical alloying and subsequent thermal treatment starting from a corresponding elemental powder mixture. The kinetics of hydrogen absorption and desorption of annealed materials were measured using a manually controlled Sieverts apparatus. The electrochemical characteristics of Mg 2 Ni-type alloys were tested for their ability to store hydrogen at room temperature by using constant current to charge and discharge the electrode. The partial substitutions of Cu and V for Ni increased hydrogen absorption and desorption at 200 • C and improved the electrochemical storage capacity and cycle life at room temperature.

A dynamic model of a discrete reversible fuel cell (RFC) system has been developed in a Matlab Simulink ® environment. The model incorporates first principles dynamic component models of a proton exchange membrane (PEM) fuel cell, a PEM electrolyzer, a metal hydride hydrogen storage tank, and a cooling system radiator, as well as empirical models of balance of plant components. Dynamic simulations show unique charging and discharging control issues and highlight factors contributing to overall system efficiency.

Experimental results of a combined absorption and electrodialysis process for the CO, recovery from the atmosphere are presented as the first step in an environmentally neutral fuel production. Furthermore, preliminary results on the electrochemical reduction of CO, on porous electrodes in aqueous solutions, on mixed oxide electrodes in a high pressure electrochemical cell in liquid CO, and some aspects of the electrochemical adsorption and reduction of CO, on Pd-Fe alloys are discussed.

This work deals with the investigations of hydrogen adsorption energies of the Li functionalized Covalent Organic Framework-366 (COF-366) by using the density functional theory method. Based on total energy calculations, it was found that Li atom is preferentially trapped at the center site of the tetra (p-amino-phenyl) porphyrin and the onN site of a terephthaldehyde chain. Moreover, hydrogen adsorption energies per H2 for 1e3 H2 loadings range from 0.03 to 0.22 eV. According to ab initio molecular dynamics simulations, our results found that hydrogen capacities of Li functionalized COF-366 at ambient pressure are 2.06, 1.58, and 1.05 wt% for 77, 150 and 298 K, respectively.

Hydrogen storage 2D NMR DFT calculations a b s t r a c t Liquid organic hydrides, e.g. 9-ethylcarbazole, are potentially interesting hydrogen storage materials because of their reversible hydrogen sorption properties. In the present work, hydrogenation reaction of 9-ethylcarbazole in the molten form was investigated over a wide variety of noble metal and nickel supported catalysts. The catalytic activity of 8.2 Â 10 À6 mol-ethylcarbazole/g of metal/s and selectivity of 98% towards a fully hydrogen loaded product were recorded over 5 wt% ruthenium on alumina which was prepared by mild chemical reduction of ruthenium salt. Using this catalyst the theoretical capacity of hydrogen uptake (5.7 wt%) was obtained and the rate of the reaction and activation energy were estimated. Due to its potential high hydrogen storage capacity, this system could be a promising on-board storage candidate for mobile applications. The structures of reaction products and intermediates were identified using 2D NMR techniques. These structures were also predicted to be thermodynamically stable using density functional theory (DFT), matching well with the experimental observations. (S.C. Tsang).

There is a need for numerical models capable of predicting local accumulation of hydrogen near stress con-centrators and crack tips to prevent and mitigate hydrogen assisted fracture in steels. The experimental char-acterisation of trapping parameters in metals, which is required for an accurate simulation of hydrogen transport, is usually performed through the electropermeation test. In order to study grain size influence and grain boundary trapping during permeation, two modelling approaches are explored; a 1D Finite Element model including trap density and binding energy as input parameters and a polycrystalline model based on the assignment of a lower diffusivity and solubility to the grain boundaries. Samples of pure iron after two different heat treatments-950 • C for 40 min and 1100 • C for 5 min-are tested applying three consecutive rising permeation steps and three decaying steps. Experimental results show that the finer grain microstructure promotes a diffusion delay due to grain boundary trapping. The usual methodology for the determination of trap densities and binding energies is revisited in which the limiting diluted and saturated cases are considered. To this purpose, apparent diffusivities are fitted including also the influence of boundary conditions and comparing results provided by the constant concentration with the constant flux assumption. Grain boundaries are char-acterised for pure iron with a binding energy between 37.8 and 39.9 kJ/mol and a low trap density but it is numerically demonstrated that saturated or diluted assumptions are not always verified, and a univocal determination of trapping parameters requires a broader range of charging conditions for permeation. The relationship between surface parameters, i.e. charging current, recombination current and surface concentrations, is also studied showing that trapping phenomena are stronger during the diluted steps and that recombination currents are much higher than the steady state obtained flux.

This study examines the use of hydrogen as an energy carrier for spreading renewable energy and mitigating environmental problems, and proposes a system for carrying clean water together with hydrogen. Practical simulations were carried out assuming the present conditions of Kazakhstan. The capital and most other large cities are located both far from clean water sources, and areas with plenty of sunshine. The proposed model consists of hydrogen generation by solar-powered electrolysis, transportation of hydrogen by railways and electric power generation using fuel cells in cities. The fuel cells also generate clean liquid water. This paper proposes a hydrogen transportation system by railway, where Ti-based hydrogen storage alloys fabricated with readily available metals in Kazakhstan are used. The railway is the most practical means of transportation compared to other methods in terms of utilities, economy, environment and time.

insight review articles NATURE | VOL 414 | 15 NOVEMBER 2001 | www.nature.com 353 E nergy can be stored in different forms: as mechanical energy (for example, potential energy or rotation energy of a flywheel); in an electric or magnetic field (capacitors and coils, respectively); as chemical energy of reactants and fuels (batteries, petrol or hydrogen); or as nuclear fuel (uranium or deuterium). Chemical and electric energy can be transmitted easily because they both involve electronic Coulomb interaction. Chemical energy is based on the energy of unpaired outer electrons (valence electrons) eager to be stabilized by electrons from other atoms. The hydrogen atom is most attractive because its electron (for charge neutrality) is accompanied by only one proton. Hydrogen thus has the best ratio of valence electrons to protons (and neutrons) of all the periodic table, and the energy gain per electron is very high.

This paper reports the major activities carried out during the failure analysis of an exploded cylinder containing hydrogen. The general cracking pattern of the cylinder, the fractographic features, and the stress analysis results were all indicative of an internal gaseous detonation. Accordingly, several specific characteristics of detonation-driven fracture of closed-end cylindrical tubes were identified. These characteristics were analyzed through detailed examinations of the fracture surfaces, cracking patterns, and dynamic stress analysis of the cylinder using a transient analytical model. Based on the size and location of special markings found on the shear lips, and using the time duration of flexural waves, the crack growth increments and speed were computed. Consequently, the basic features of the gaseous detonation and the composition of the original gas mixture were identified. The results indicated that the detonation of a low-pressure oxygen-rich mixture of hydrogen and oxygen was the cause of this failure. The presence of oxygen was attributed to an improper usage of an oxygen cylinder for hydrogen storage.

We predict the stability of a new extended two-dimensional hydrocarbon on the basis of first-principles total energy calculations. The compound that we call graphane is a fully saturated hydrocarbon derived from a single graphene sheet with formula CH. All of the carbon atoms are in sp 3 hybridization forming a hexagonal network and the hydrogen atoms are bonded to carbon on both sides of the plane in an alternating manner. Graphane is predicted to be stable with a binding energy comparable to other hydrocarbons such as benzene, cyclohexane, and polyethylene. We discuss possible routes for synthesizing graphane and potential applications as a hydrogen storage material and in two dimensional electronics.

Slush hydrogen is a mixture of liquid and frozen hydrogen in equilibrium with the gas at the triple point. Slush hydrogen is expected to be the primary propellant for the National Aero-Space Plane (NASP) because of its potential for reducing the plane's size and significantly cutting the projected gross lift-off weight. This paper provides an overview of slush hydrogen production methods and reviews the current state of knowledge regarding slush hydrogen utilization.

A new generation of porous polymers was made for various energy-related applications, e.g., as fuel cell membranes, as electrode materials for batteries, for gas storage, partly from renewable resources. This review intends to catch this emerging field by reporting on a variety of different approaches to make high performing polymers porous. This includes template techniques, polymers with inherent microporosity, polymer frameworks by ionothermal polymerization, and the polymerization of carbon from appropriate precursors and by hydrothermal polymerization. In this process, we try to not only identify the current status of the field, but also point to open question and tasks to identify the potentially relevant progress.

Nanomaterials have diverse tunable physical properties as a function of their size and shape due to strong quantum confinement effect and large surface to volume ratio. On basis of these facts, nanocomposite materials can be considered as strong candidates for hydrogen storage. In the present work, we report a novel conducting polymeric nanocomposite material for hydrogen storage. Conducting polymer-based nanocomposites were modified using carbon nanotubes as filler material. This further increased the porous structure of the nanocomposite and the number of binding sites, which in turn enhances the hydrogen storage capacity. Additionally, fine aluminum powder was added to the polymeric nanocomposite, which further increased the hydrogen sorption of the material. The modified conducting polymeric nanocomposites were characterized with various analytical techniques including FTIR, DSC, TGA and SEM. Adsorption and desorption experiments are conducted using a Sieverts-type volumetric PCT instrument. Further experiments are in progress to understand the hydrogen storage mechanism in the proposed conducting polymer nanocomposites. ᭧