Solution For Hydrogen Storage Research Articles

Hydrogen adsorption behavior on AXenes Na2N and K2N: a first-principles study

It is a consensus that the hydrogen economy has come to a standstill due to the lack of feasible hydrogen storage solutions, especially, the suitable hydrogen storage materials. In this work, the potential of a new kind of two-dimensional (2D) AXenes, Na2N and K2N, as hydrogen storage materials are evaluated by the first-principles calculations. In particular, we find that Na2N in T phase indicates a hydrogen storage capacity as high as 6.25 wt% with a desirable hydrogen adsorption energy of –0.167 eV per H2 molecule and a desorption temperature of 216 K, identifying T-phase Na2N to be a very promising reversible hydrogen storage material. In accordance to our results, H2–Na2N interaction causes H2 charge polarization, which is responsible for the moderate binding strength. In addition, Gibbs adsorption free energy reveals that the system will be more stable as more H2 molecules are loaded on the surface.

How a hydrogen start-up can contribute to the energy transition through the emerging hydrogen economy

How a hydrogen start-up can contribute to the energy transition through the emerging hydrogen economy

Impact of catalyst loading, ionomer content, and carbon support on the performance of direct isopropanol fuel cells

Liquid Organic Hydrogen Carriers (LOHC) offer a promising solution for hydrogen storage in the existing infrastructure for conventional fuels. Within this framework, the isopropanol/acetone couple as a light-LOHC system is used to generate electricity in a direct isopropanol fuel cell (DIFC). This work focuses on the impact of catalyst loading, ionomer content and catalyst support on the performance of DIFCs. We achieve a performance rise from 95 mW cm -2 to 219 mW cm -2 under air operation by increasing the anode catalyst loading from 0.5 mg cm -2 to 4 mg cm -2 , which can be attributed to the increased abundance of active catalyst sites with higher loadings. In contrast, we find that the cathode loading for the oxygen reduction reaction (ORR) plays a minor role in the performance of DIFCs. Therefore, the cathode loading can be minimized to decrease the total amount of platinum-group metals and, consequently, to save cost. It was also found that an ionomer content of 30% on the anode side is optimal. Additionally, different carbon supports were investigated, where advanced high surface area carbon support showed superior performance to Vulcan with an increase of 20% in power density, motivating the development of new carbon supports for DIFCs. • PtRu catalyst loading on the anode is critical for the performance of direct isopropanol fuel cells. • Cathode Pt loading plays a minor role and can be reduced or even exchanged with PGM-free ORR catalysts. • An ionomer content of 30 wt% (I/C 1.07) is optimal for the anode catalyst layer. • Advanced high surface area carbon support leads to record-high power densities with 259 mW cm −2 at 0.55 V and air operation. • Dynamic operation reveals the potential of isopropanol oxidation without catalyst poisoning.

Feasibility analysis of an innovative naval on-board power-train system with hydrogen- based PEMFC technology

The maritime transportation sector is one of the main contributors to global emissions of greenhouse gases (GHGs), volatile organic compounds (VOCs), particulate matter (PM), hazardous air pollutants, NOX and SOX. In particular, it is estimated that the CO2 emissions in this sector are about 1 Gt every year. The International Maritime Organization (IMO) adopted stringent emission limits in its Tier III regulation, most notably on NOX and SOX emissions and pledged to reach a reduction in greenhouse gas (GHG) emissions from international shipments by at least 50% by the year 2050, compared to 2008 emissions. For emission control areas (ECAs) these requirements are particularly strict and will be difficult to meet with traditional diesel engines and bunker fuels. Therefore, ship owners need to adopt solutions to bring emissions within these and other future limits by means of environmentally friendly fuels and high efficiency propulsion technologies. In this context, hydrogen and fuel cells play a crucial role, thanks to their low criteria pollutant and GHG emission. This paper presents a techno-economic feasibility study for replacing the conventional diesel engine powertrain, usually employed in Ro-Pax ferries, with an innovative system based on polymer electrolyte membrane fuel cell (PEMFC) technology. The ferry is actually powered by four diesel engines, which deliver a total output of 37.8 MW. The ferry also has two auxiliary engines which give an output of 4.0 MW and also two 2.0 MW bow thrusters for its manoeuvring. The energy analysis has allowed to define the hydrogen consumption for each cruise, as well as the optimal size of the innovative propulsion system. In particular, The PEMFC powertrain is sized at the same maximum power output as the main diesel engine and, thanks to the modular architecture of fuel cells and their flexible performance at partial load, the auxiliary engines are not contemplated. Moreover, in order to identify the best solution in terms of ship’s weight and space requirements, two hydrogen storage solutions based on compressed hydrogen technology and liquefied hydrogen technology, have been analyzed and compared. The economic assessment has been carried out by estimating the CAPEX and OPEX for each H2 storage technology by considering short-term, mid-term and long-term scenarios (from 2020 to 2050).

Stress reduction in a hydride container by the addition of a glidant agent

Hydrogen absorbing materials, such as metal hydrides, present a possible solution for hydrogen storage. During the absorption process these materials swell, which can put the mechanical integrity of its container at risk. One possibility is to increase the flowability of the absorbing material, usually a fine cohesive powder, so that it can rearrange within its container during the swelling stage. In this work, we study if this rearrangement could be improved by the addition of Aerosil, a type of colloidal silica widely used as glidant agent. The walls of a stainless steel reactor are instrumented with strain gauges to measure the accumulation of stresses due to hydrogen absorption-desorption cycles. We explore the container filled with pure LaNi5 absorbing material previously activated, so as with different Aerosil-added proportions. Results show that Aerosil allows avoiding stress build-up, for all glidant concentrations used in present study.

Fast hydrogen absorption/desorption kinetics in reactive milled Mg-8 mol% Fe nanocomposites

This study aims to better understand the Fe role in the hydrogen sorption kinetics of Mg–Fe composites. Mg-8 mol% Fe nanocomposites produced by high energy reactive milling (RM) for 10 h resulted in MgH2 mixed with free Fe and a low fraction of Mg2FeH6. Increasing milling time to 24 h allowed formation of a high fraction of Mg2FeH6 mixed with MgH2. The hydrogen absorption/desorption behavior of the nanocomposites reactive milled for 10 and 24 h was investigated by in-situ synchrotron X-ray diffraction, thermal analyses and kinetics measurements in Sieverts-type apparatus. It was found that both 10 and 24 h milled nanocomposites presents extremely fast hydrogen absorption/desorption kinetics in relatively mild conditions, i.e., 300–350 °C under 10 bar H2 for absorption and 0.13 bar H2 for desorption. Nanocomposites with MgH2, low Fe fraction and no Mg2FeH6 are suggested to be the most appropriate solution for hydrogen storage under the mild conditions studied.

Electrostimulated Desorption Hydrogen Sensor Based on Onion-Like Carbons as a Sensing Element

Within this paper, a hydrogen sensor based on onion-like carbons (OLCs) is proposed and its behaviour is assessed in detail. The OLCs prove to be ideal candidates for the development of solid-state sensing technology of hydrogen working at room temperature, due to their hydrophobic nature and their non-porous texture. Using dielectrophoreis as a method of electromanipulation, the OLCs undergo ultrasonication in ethanol and, according to the analysis results through the Fourier transform infrared (FT-IR) spectra of OLC/C2H6O nanoparticles showed significant structural changes compared to the pristine OLCs. The fullerene C60 nanoparticles exposed to ethanol can present several solvation shells around the central fullerene molecule, and in the first layer of the solvation shell, ethanol molecules tend to form non-polar alkyl groups exposed to the surface, which contributes to the stimulation of structural defects of the OLC layers. The fast decrease in resistance of the OLC/C2H6O sensor under 10 ppm H2 exposure can be attributed to the switch of the nanoparticles to n-type semiconductor behaviour together with the additional increase in the number of electrons in the conduction band. Countless carbon-based sensing devices were previously reported, but the major drawback of these solutions was the irreversible response to hydrogen because of the high energy required by the adsorbed binding molecules to desorb from the material at low working temperatures. The sensor presented exploits the binding capacity of hydrogen to OLCs/C2H6O, as demonstrated by the previously proposed hydrogen storage solutions based on these fullerenes. In order to ensure sensors enhanced operability at room temperature current, stimulated desorption was used to stimulate desorption of the analyte molecules in the absence of an external heating source.

Team Works on New Hydrogen Storage Solution

Porous materials could safely take in and release gas inside vehicles

McPhy delivers 4 MW of hydrogen production to China for P2G application with wind farm

French hydrogen technology manufacturer McPhy has delivered 4 MW of hydrogen production equipment to Jiantou Yanshan (Guyuan) Wind Energy in China, for a Power-to-Gas (P2G) application in Hebei Province. The McPhy system, in combination with a solid-state hydrogen storage solution, makes it possible to transform renewably produced electricity and store the surplus energy generated by a 200 MW wind farm.

Development of Mg[sbnd]Li[sbnd]B based advanced material for onboard hydrogen storage solution

Lithium borohydride-magnesium hydride (LiBH4–MgH2) reactive composite has been considered as one of the potential candidate for energy storage in the form of hydrogen because of its high hydrogen storage capacity. The composite requires high temperature (>500 °C) to dehydrogenate above 80% of its theoretical hydrogen storage capacity due to kinetic constraints. Therefore, a suitable catalyst is required to lower the dehydrogenation temperature. In this regard, the catalytic effect of ZrCl4 on the dehydrogenation of LiBH4–MgH2 reactive composite has been studied. It was found that the apparent activation energy of dehydrogenation decreases considerably followed by reduction in onset dehydrogenation temperature. The X-ray diffraction analysis of dehydrogenated composite has shown two phase of MgLi intermetallics. The formation of MgLi intermetallic phases eventually increases the amount of hydrogen release and, it could be beneficial during rehydrogenation. Moreover, dehydrogenation of catalyzed MgH2–LiBH4 favors the formation of MgB2 under mild conditions.

Suppression of Phase Transformation in Nb-H Thin Films below Switchover Thickness.

Hydrogen uptake in metal-hydrogen (M-H) nanosized systems (e.g., thin films, clusters) is both a fundamental and a technologically relevant topic, which is becoming more important due to the recent developments of hydrogen sensors, purification membranes, and hydrogen storage solutions. It was recently shown that hydrogen (H) absorption in nanosized systems adhered to rigid substrates can lead to ultrahigh mechanical stress in the GPa range. About -10 GPa (compressive) stress were reported for hydrogen loaded niobium (Nb) thin films. Such high stresses can be achieved when conventional stress-release channels are closed, e.g., by reducing the system size. In this paper, we demonstrate that the high stress can be used to strongly modify the system's thermodynamics. In particular, a complete suppression of the phase transformation is achieved by reducing the film thickness below a switchover value dso. Combined in situ scanning tunneling microscopy (STM) and in situ X-ray diffraction (XRD) measurements serve to determine the switchover thickness of epitaxial Nb/Al2O3 films in the thickness range from 55 to 5 nm. A switchover thickness dso = 9 ± 1 nm is found at T = 294 K. This result is supported by complementary methods such as electromotive force (EMF), electrical resistance, and mechanical stress measurements in combination with theoretical modeling.

Trapping of hydrogen atoms inside small beryllium clusters and their ions

Structure, stability and electronic properties are evaluated computationally for small Ben (n=5–9) cluster cages accommodating atomic H inside and forming core-shell species. These parameters are predicted to vary significantly upon insertion of H, for ionic derivatives, and with the system size. In particular, the energy barrier for H-atom exit from the cage changes significantly for ions compared to the neutral counterparts. The corresponding effects predicted for cage assemblies suggest the possibility of efficient charge-control of hydrogen release. This, together with a high capacity for storing hydrogen in extended such assemblies might indicate a possible way towards feasible hydrogen-storage solutions.

In operando visualization of hydride-graphite composites during cyclic hydrogenation by high-resolution neutron imaging

Hydrogen solid-state storage in metal hydrides has attracted remarkable attention within the past decades due to their high volumetric storage densities at low operating pressures. In particular, recently emerged hydride-graphite composites (HGC) can enable a safe, reliable and very compact hydrogen storage solution for various applications. In this regard, only little is known about the activation behavior of such HGC, their cycle stability and degradation effects. Because of the high sensitivity to hydrogen, neutron imaging offers a distinctive approach to examine in operando reaction fronts, swelling effects and microstructural changes of hydrogen absorbing materials with high spatial and temporal resolution. In this contribution, a comprehensive analysis of various phenomena during activation and cycling of HGC based on a Ti–Mn hydrogen absorbing alloy and expanded natural graphite is reported for the first time. A neutron radiography and tomography set-up with a spatial resolution down to 7 μm was utilized allowing highest detection precision. During initial hydrogenation, regions with enhanced reactivity are observed which contradicts a theoretically expected homogeneous reactivity inside the HGC. These active regions grow with the number of hydrogenation-dehydrogenation cycles until the whole HGC volume uniformly participates in the hydrogen sorption reaction. With regard to long-term hydrogenation-dehydrogenation cycling, inhomogeneous swelling effects were observed from which essential conclusions for technical HGC-based tank systems can be derived.

High performance FeTi – 3.1 mass % V alloy for on board hydrogen storage solution

Single phase FeTi intermetallic and FeTi-3.1 mass % V alloy were synthesized by vacuum arc melting using high purity elemental constituents. The crystal structure of both, FeTi intermetallic and FeTi-3.1 mass % V alloy was found to be of CsCl-type. Under similar annealing conditions, crystallite size of FeTi-3.1 mass % V alloy was markedly smaller than that of FeTi intermetallic. Hydrogen absorption in FeTi intermetallic and FeTi-3.1 mass % V alloy was studied in a thermobalance attached to a Sieverts apparatus at a temperature of 327 K under 0.2 MPa hydrogen pressure. The hydrogen absorption in vanadium alloyed FeTi matrix was significantly faster than in the pure intermetallic. The maximum amount of hydrogen absorbed in the FeTi intermetallic and FeTi-3.1 mass % V alloy was of 1.2 and 1.1 mass % respectively.

Structural Characterization of Mg2CoH5-based Nanocomposites for Hydrogen Storage

Hydrogen is considered the ideal energy carrier, mainly due to its heating power, the highest among all chemical fuels, and to possibility of using it in fuel cells, therefore with efficiency and producing only water as by-product. However, the development of safe and effective hydrogen storage solutions remains as a challenge of applied research. MgH2, Mg2FeH6 and Mg2CoH5complex hydrides are promising materials for hydrogen storage, avoiding the inconvenient of gaseous or liquid storage alternatives. The main attractives of these phases are their volumetric and gravimetric hydrogen capacities, their reversibility during absorption/desorption cycles and the relatively low cost. Recently, we have achieved an important control of the synthesis of Mg-based complex hydrides with nanocrystalline structure, using reactive milling (RM) under hydrogen atmosphere as processing route [1, 2]. In this study, we present new results concerning the synthesis, hydrogen storage properties and structural characterization of MgH2–Mg2CoH5nanocomposites prepared by RM. The nanocomposites were produced by milling different Mg-Co starting compositions (2:1, 3:1, 5:1, 7:1, 1:0) for 12 h in a planetary mill under 3 MPa of H2. All samples were fully hydrogenated during milling, generating different MgH2–Mg2CoH5hydride mixtures. Mg presents the tendency of agglomerate during milling, so the sample that presents more MgH2shows larger agglomerates. This behavior causes a slight increase in the temperature of hydrogen desorption and the presence of two peaks, showed by DSC analysis for those samples which presents MgH2and Mg2CoH5. Using in-situ XRD and XANES during hydrogen desorption revealed that Mg and Co tend to remain coupled forming intermetallics after the complex hydride decomposition, differently from that was observed for Mg2FeH6. This effect is correlated to the high-reversibility exhibited by the Mg2CoH5phase. Furthermore, the nanocomposites of MgH2+Mg2CoH5showed better H-absorption/desorption kinetics than the Mg2CoH5or MgH2alone, as shown by volumetric measurements. The combination of MgH2and Mg2CoH5is therefore a promising strategy to produce hydrogen storage materials, matching the good reversibility and high capacity of magnesium hydride with the lower thermal stability.

Cover Picture: Realizing the Storage of Pressurized Hydrogen in Carbon Nanotubes Sealed with Aqueous Valves (Energy Technol. 5‐6/2013)

Nanoscale Tanks for Pressurized Hydrogen Storage: Hydrogen has long been recognized as a clean and renewable fuel with great promise, as water is the only by-product from the consumption of abundantly available hydrogen fuel. However, the practical utilization of hydrogen fuel is severely restricted by the lack of a viable solution for hydrogen storage. In automotive applications, the use of heavy stainless-steel cylinders of pressurized hydrogen not only reduces the energy efficiency substantially, but also poses a serious safety issue. The Communication by Ka-wai Wong and colleagues at Chengdu Green Energy and Green Manufacturing R & D Center on page page 309 demonstrates that single-walled carbon nanotubes can be used to store pressurized hydrogen by using aqueous valves to seal the ends. The storage and release of hydrogen with these nanocapsules was thermally controlled by heating the nanotubes above the melting temperature of the ice. In this proof of concept, hydrogen was stored at a pressure of 5.0 MPa without significant leakage. Preliminary estimation reveals that an attractive gravimetric energy efficiency as high as 9 % would be achieved at a storage pressure of 1 GPa hydrogen.

Solid-state hydrogen storage in Hydralloy–graphite composites

Hydrogen-based power systems require safe, efficient and robust hydrogen storage solutions. In this regard, metal hydrides become increasingly important because of their extremely high volumetric hydrogen capacity and their moderate operation pressures. The loading and unloading dynamics of hydride-based hydrogen tanks is mainly influenced by the intrinsic hydrogen sorption kinetics of the storage material as well as by the heat and gas transport properties of the hydride bed.In this contribution, pelletized composites of the room-temperature hydrogen storage material Hydralloy C52 (AB2-type) with expanded natural graphite (ENG) are discussed in view of high-dynamic hydrogen solid-state storage applications. Powdery Hydralloy C52 is blended with up to 12.5 wt.% ENG. The blend is pelletized at compaction pressures up to 600 MPa. The Hydralloy–ENG pellets exhibit an increased effective thermal conductivity and provide an increased volumetric H2 storage capacity compared to loose powders. The hydrogenation behavior at different temperatures and for various hydrogenation–dehydrogenation cycles is discussed. Furthermore, the stability of the pellets throughout cyclic hydrogenation is evaluated. High gas permeability in radial direction and sufficient thermal conductivity in combination with a stable pellet structure underline the potential of Hydralloy–ENG composites for hydrogen storage applications with high loading dynamics.

Complex inorganic structures from powder diffraction:case of tetrahydroborates of light metals

Abstract Powder diffraction plays a central role in the characterization of light metal tetrahydroborates (borohydrides), novel boron based hydrides recognized as a potential solution for hydrogen storage. Numerous novel BH– 4 based materials have been investigated during the past few years and this class of materials has a fascinating structural chemistry. We review the powder diffraction methods, problems and solutions which are specific for these weakly diffracting and badly crystallized materials. Examples of highlights and pitfalls of the powder diffraction are given. Complex structures with as many as 55 independent atoms were fully characterized, and P-T phase diagrams accessible from in-situ powder diffraction enable understanding of these ionic crystals with important directional bonding.

The Hype About Hydrogen

Review: The Hype About Hydrogen By Joseph J. Romm Reviewed by Umar Karim Mirza Pakistan Institute of Engineering and Applied Sciences, Pakistan Joseph J. Romm. The Hype About Hydrogen. Washington, DC: Island Press, 2004. 256 pp. ISBN: 1-55963-703-X. US$ 25.00. (Hardcover). Acid-free Paper. During Clinton administration the author, Joseph J. Romm, served in various positions in the Department of Energy. Currently he is the Executive Director of the Center for Energy and Climate Solutions, and a Principal with the Capital E Group. He has authored two other useful books: Cool Companies: How the Best Businesses Boost Profits and Productivity by Cutting Greenhouse Gas Emissions. The Hype About Hydrogen describes in detail what is going on in the world of hydrogen. Many as the solution to all our energy problems, both resource- related and environmental ones label hydrogen economy. Romm’s position is that we must eventually have a hydrogen economy based on the hydrogen fuel cell, but this cannot be expected to happen soon or without some major technological breakthroughs. He warns that the global warming clock is ticking very fast, and something needs to be done now to avoid a possible catastrophe. In the introduction to the book, Romm explains what ‘Hydrogen Economy’ means, how it relates to climate and what is the realistic view about it. The first chapter answers the fundamental question: why do we need hydrogen and why now? The growing energy and environmental risks have prompted us to look toward hydrogen. Fuel cell basics, simplified working principle and different types are described in chapter 2. The following chapter introduces the path to fuel cell commercialization. Hydrogen production is dealt with in chapter 4. Presently steam methane reforming generates about 90 percent of U.S. hydrogen. Other common sources include water, gasoline, methanol, coal and biomass. Electricity generated from nuclear power or renewable energy resources can also be used to produce hydrogen through electrolysis of water. Hydrogen-based transportation systems are discussed in the next chapter. Hydrogen must be liquefied or compressed before it could be used as a transportation fuel. Metal hydrides are another promising solution for hydrogen storage. However, huge infrastructure is needed for nationwide storage and delivery, and there are safety issues as well with hydrogen use. Romm explains the long road to commercialization of fuel cell vehicles in chapter 6. Global warming and climate change issues are discussed in

Room temperature micro-hydrogen-generator

A new compact and cost-effective hydrogen-gas generator has been made that is well suited for supplying hydrogen to a fuel-cell for providing base electrical power to hand-carried appliances. This hydrogen-generator operates at room temperature, ambient pressure and is orientation-independent. The hydrogen-gas is generated by the heterogeneous catalytic hydrolysis of aqueous alkaline borohydride solution as it flows into a micro-reactor. This reactor has a membrane as one wall. Using the membrane keeps the liquid in the reactor, but allows the hydrogen-gas to pass out of the reactor to a fuel-cell anode. Aqueous alkaline 30 wt% borohydride solution is safe and promotes long application life, because this solution is non-toxic, non-flammable, and is a high energy-density (≥2200 W-h per liter or per kilogram) hydrogen-storage solution. The hydrogen is released from this storage-solution only when it passes over the solid catalyst surface in the reactor, so controlling the flow of the solution over the catalyst controls the rate of hydrogen-gas generation. This allows hydrogen generation to be matched to hydrogen consumption in the fuel-cell, so there is virtually no free hydrogen-gas during power generation. A hydrogen-generator scaled for a system to provide about 10 W electrical power is described here. However, the technology is expected to be scalable for systems providing power spanning from 1 W to kW levels.