Metal Hydride Hydrogen Storage Research Articles

CONCEPT OF THE AUTONOMOUS HYDROGEN FUELLING STATION BASED ON PHOTOVOLTAIC AND METAL-HYDRIDE TECHNOLOGIES FOR FUEL CELL ELECRIC VEHICLE. DEVELOPMENT OF A GENERAL CONCEPT FOR AN AUTONOMOUS HYDROGEN FUELLING STATION WITH METAL HYDRIDE COMPRESSORS FOR VEHICLES ON FUEL CELLS

At present time internal combustion engines (ICE) are the most spread as main and auxiliary ICE for vehicles, vessels, power generation, etc. Their application is associated with low energy efficiency, negative impact on the environment due to high emissions of harmful substances and the use of oil fuels. The vehicles with electric motors are alternative upon to existing ones. There are two modern concepts of the electric vehicles: battery electric vehicles and electric vehicles with fuel cells. The main advantage of the battery electric vehicles is the developed infrastructure of power grids and charging stations, but the charging time is too prolonged (from 20 minutes in the fast charging mode and up to 8…10 hours. Unfortunately the fast mode significantly reduces life cycle of the electric batteries. One of the advanced alternatives is concept of the fuel cell and hydrogen powered vehicles. It exist some problems which limit its wide implementation. There are the following: high cost of hydrogen production, insufficient amount of electricity production and transmission capacity of electric networks for mass charging of electric vehicles. These problems can be solved by creation of the complexes for local hydrogen production by water electrolysis on the base of photovoltaic panels, hydrogen purification and compression on the base of metal-hydride technologies and hydrogen storage in ultra-light-weight high pressure thanks on the base of reinforced with carbon nanotubes or composite materials. Implementation of this concept will allow to get rid of disadvantages which are inherent in vehicles with electrical batteries. The most of these are the following: high mass and cost, limited run distance and long charging time, short life cycle and recycling batteries pollution. The charging duration of hydrogen high pressure tanks is 5...15 min and is comparable with the ICE diesel/gasoline fueling terms and conditions. One of the main obstacles to expanding vehicles on fuel cells is the deficit of hydrogen and its filling stations. At present it is known a number of solutions for the creation of hydrogen fueling. However, today there is no single standard solution for hydrogen charging. Until today, vehicles running on hydrogen (both fuel cells and equipped with ICE that consume hydrogen), several options for its storage are used. There are high pressure tanks with hydrogen gas compressed at 35…70 MPa. Judging by the vehicles technologies and concepts the combination of fuel cells with tanks at 70 MPa will be the most common variant of hydrogen technology promotion in the coming years. In connection with the variety of hydrogen storage options on board vehicles, it is actual to develop autonomous fueling stations with photovoltaic panels for electricity production with following hydrogen production by electrolysis, hydrogen purification and compression by metal-hydride technology and hydrogen storage in super high pressure tanks or metalhydride tanks with the possibility of hydrogen charging at different pressures from 35 MPa up to 150 MPa.

Parametric optimization and control toward the design of a smart metal hydride refueling system

AbstractIn this paper, we present an extension of the parametric optimization and control (PAROC) framework toward the design of a novel smart metal hydride storage system. Both in silico and laboratory implementation are considered toward a smart prototype system application. In silico PAROC considerations include the development and validation of high‐fidelity model and the derivation of explicit optimal feedback law through the solution of a receding horizon parametric optimization problem formulation. The derived explicit parametric control strategy is validated first in silico then in real time. A laboratory scale metal hydride hydrogen storage system is designed and built as a prototype to replicate the refueling process of a fuel cell electric vehicle (FCEV) in a hydrogen gas station. Integration of the explicit model predictive control feedback law into the prototype system creates a smart metal hydride storage technology that can be deployed for onboard hydrogen storage in an FCEV. The results obtained from the real‐time implementation of the explicit feedback law demonstrate an effective thermal management of the refueling operation in a metal hydride system.

Application of data science tools to determine feature correlation and cluster metal hydrides for hydrogen storage

In this paper, the openly available database provided by the US Department of Energy on hydride metals for hydrogen energy were studied through unsupervised machine learning to identify the similarities in samples which are originally classified in various material classes. We employed k-means algorithm to investigate the similar behaviour of different materials classes in relation to hydrogen weight percent and operating parameters. It was found that the optimal number of clusters within the dataset is 3 despite the fact that the data points are classified in eight different material classes. We employed discrete linear convolution method for anomaly detection and to identified irregularities and outliers in the dataset. In addition, kernel density estimations was employed and the results showed that most data points are located in the temperature range between 0 and 200 ∘C, pressure between 0 to 5 atm and hydrogen weight percent between 0-2 wt.%. Our investigation showed that most of the outliers belong to complex material class. The analysis of clustering behaviour showed that A2B, complex hydrides and Mg-based alloys clustered together, which is supported by the fact that many samples with the same structures belong to these three classes simultaneously. It was also found that the removal of temperature or heat of formation significantly changes the clustering behaviour. The proposed method in this study can be used to find the closest material chemistry for a desired set of properties.

Nitrogen-stimulated superior catalytic activity of niobium oxide for fast full hydrogenation of magnesium at ambient temperature

Magnesium hydride (MgH2) is one of the most promising high-capacity hydrogen storage materials. However, limited progress has been made in storing hydrogen in Mg under ambient conditions. Here, we demonstrate for the first time that the dehydrogenated MgH2 is fully hydrogenated below 100 °C with the presence of N-containing Nb2O5 (N-Nb2O5). MgH2 composites doped with N-Nb2O5 (10 wt%) releases hydrogen from 170 °C, which is lowered by 130 °C compared with pristine MgH2, while still having 6.3 wt% hydrogen capacity available. Most importantly, full hydrogenation can be achieved by the dehydrogenated N-Nb2O5-containing sample at temperature as low as 70 °C under 50 atm of hydrogen, which is superior to other known catalyst-doped MgH2 systems. The in-situ formed NbN0.9O0.1 plays the critical catalyst role due to the joint action of N and Nb as elucidated by density functional theory (DFT) calculations. This finding remarkably facilitates the future design and exploration of much higher-performance catalysts for room-temperature hydrogen storage in metal hydrides.

Thermal management of metal hydride hydrogen storage reservoir using phase change materials

Metal hydride hydrogen storage reservoir should be carefully designed to achieve acceptable performance due to significant thermal effect on the system during hydriding/dehydriding. Phase change materials can be applied to metal hydride hydrogen storage system in order to improve the system performance. A transient two-dimensional axisymmetric numerical model for the metal hydride reservoir packed with LaNi5 has been developed on Comsol platform, which was validated by comparing the simulation results with the experiment data from other work. Then, the performances of metal hydride hydrogen storage reservoir using phase change materials were predicted. The effects of some parameters, such as the thermal conductivity, the mass and the latent heat of fusion of the phase change materials, on the metal hydride hydrogen storage reservoir were discussed. The results shown that it was good way to improve the efficiency of the system by increasing the thermal conductivity of phase change materials and selecting a relatively larger latent heat of fusion. Due to the relatively lower thermal conductivity of phase change materials, different metal foams were composited with the phase change materials in order to improve the heat transfer from the metal hydride bed to the phase change materials and the hydrogen storage efficiency. The effect of aluminium foam on the metal hydride reservoir was studied and validated. The phase change materials composited with copper foam shown better performance than that composited with aluminium foam.

Concept of the autonomous hydrogen fuelling station based on photovoltaic and metal-hydride technologies for fuel cell elecric vehicle. Analysis of existing fuelling stations types and vehicles using hydrogen, hydrogen production and storing methods

At present time internal combustion engines (ICE) are the most spread as main and auxiliary ICE for vehicles, vessels, power generation, etc. Their application is associated with low energy efficiency, negative impact on the environment due to high emissions of harmful substances and the use of oil fuels. The vehicles with electric motors are alternative upon to existing ones. There are two modern concepts of the electric vehicles: battery electric vehicles and electric vehicles with fuel cells. The main advantage of the battery electric vehicles is the developed infrastructure of power grids and charging stations, but the charging time is too prolonged (from 20 minutes in the fast charging mode and up to 8…10 hours. Unfortunately the fast mode significantly reduces life cycle of the electric batteries. One of the advanced alternatives is concept of the fuel cell and hydrogen powered vehicles. It exist some problems which limit its wide implementation. There are the following: high cost of hydrogen production, insufficient amount of electricity production and transmission capacity of electric networks for mass charging of electric vehicles. These problems can be solved by creation of the complexes for local hydrogen production by water electrolysis on the base of photovoltaic panels, hydrogen purification and compression on the base of metal-hydride technologies and hydrogen storage in ultra-light-weight high pressure thanks on the base of reinforced with carbon nanotubes or composite materials. Implementation of this concept will allow to get rid of disadvantages which are inherent in vehicles with electrical batteries. The most of these are the following: high mass and cost, limited run distance and long charging time, short life cycle and recycling batteries pollution. The charging duration of hydrogen high pressure tanks is 5...15 min and is comparable with the ICE diesel/gasoline fueling terms and conditions. One of the main obstacles to expanding vehicles on fuel cells is the deficit of hydrogen and its filling stations. At present it is known a number of solutions for the creation of hydrogen fueling. However, today there is no single standard solution for hydrogen charging. Until today, vehicles running on hydrogen (both fuel cells and equipped with ICE that consume hydrogen), several options for its storage are used. There are high pressure tanks with hydrogen gas compressed at 35…70 MPa. Judging by the vehicles technologies and concepts the combination of fuel cells with tanks at 70 MPa will be the most common variant of hydrogen technology promotion in the coming years. In connection with the variety of hydrogen storage options on board vehicles, it is actual to develop autonomous fueling stations with photovoltaic panels for electricity production with following hydrogen production by electrolysis, hydrogen purification and compression by metal-hydride technology and hydrogen storage in super high pressure tanks or metalhydride tanks with the possibility of hydrogen charging at different pressures from 35 MPa up to 150 MPa.

Metal hydride hydrogen storage tank for fuel cell utility vehicles

The “low-temperature” intermetallic hydrides with hydrogen storage capacities below 2 wt% can provide compact H2 storage simultaneously serving as a ballast. Thus, their low weight capacity, which is usually considered as a major disadvantage to their use in vehicular H2 storage applications, is an advantage for the heavy duty utility vehicles. Here, we present new engineering solutions of a MH hydrogen storage tank for fuel cell utility vehicles which combines compactness, adjustable high weight, as well as good dynamics of hydrogen charge/discharge. The tank is an assembly of several MH cassettes each comprising several MH containers made of stainless steel tube with embedded (pressed-in) perforated copper fins and filled with a powder of a composite MH material which contains AB2- and AB5-type hydride forming alloys and expanded natural graphite. The assembly of the MH containers staggered together with heating/cooling tubes in the cassette is encased in molten lead followed by the solidification of the latter. The tank can provide >2 h long H2 supply to the fuel cell stack operated at 11 kWe (H2 flow rate of 120 NL/min). The refuelling time of the MH tank (T = 15–20 °C, P(H2) = 100–150 bar) is about 15–20 min.

Machine learning based prediction of metal hydrides for hydrogen storage, part I: Prediction of hydrogen weight percent

The openly available database provided by the US Department of Energy on hydrides for hydrogen storage were analyzed through supervised machine learning to rank features in terms of their importance for determining hydrogen storage capacity referred to as hydrogen weight percent. In this part: we employed four models, namely linear regression, neural network, Bayesian linear regression and boosted decision tree to predict the hydrogen weight percent. For each algorithm, the scored labels were compared to the actual values of hydrogen weight percent. Our investigation showed that boosted decision tree regression performed better than the other algorithms achieving a coefficient of determination of 0.83.

Machine learning based prediction of metal hydrides for hydrogen storage, part II: Prediction of material class

The openly available dataset on hydrogen storage materials provided by the US Department of Energy was used to predict the optimal materials class of metal hydrides based on the desired properties, which included hydrogen-weight percent, heat of formation and operating temperature and pressure. We performed correlation and statistical analyses to investigate the statistical characteristics of each numeric features. We employed four classification algorithms: multiclass logistic regression, multiclass decision forest, multiclass decision jungle and multiclass neural network. Feature importance analysis was carried out to investigate how each classifier utilises the information available in the dataset. In overall, multiclass neural network classifier had better classification performance obtaining an accuracy of 0.80. The results suggest that the complex material class, followed by Mg is applicable for the most wide range of operating temperatures. Positive correlation was found between hydrogen weight percent, heat of formation and temperature, suggesting that the maximum hydrogen weight percent would be achieved in the complex material class operated at a high temperature.

Metal hydride hydrogen storage tank for light fuel cell vehicle

We describe a metal hydride (MH) hydrogen storage tank for light fuel cell vehicle application developed at HySA Systems. A multi-component AB2-type hydrogen storage alloy was produced by vacuum induction melting (10 kg per a load) at our industrial-scale facility. The MH alloy has acceptable H sorption performance, including reversible H storage capacity up to ∼170 NL/kg (1.5 wt% H). The cassette-type MH tank was made up of 2 cylindrical aluminium canisters with transversal internal copper fins and external aluminium fins for improving the heat exchange between the heating medium and the MH tank. Heat supply and removal was provided from the outside using air at T = 15–25 °C. The MH tank was tested at the conditions of natural or forced (velocity ∼2 m/s) air convection. The tests included H2 charge of the tank at P = 15–40 bar and its discharge at P = 1 bar. The tank in the H2 discharge mode was also tested together with open cathode low-temperature proton exchange membrane fuel cell (LT PEMFC).

Application of hydrides in hydrogen storage and compression: Achievements, outlook and perspectives

Metal hydrides are known as a potential efficient, low-risk option for high-density hydrogen storage since the late 1970s. In this paper, the present status and the future perspectives of the use of metal hydrides for hydrogen storage are discussed. Since the early 1990s, interstitial metal hydrides are known as base materials for Ni – metal hydride rechargeable batteries. For hydrogen storage, metal hydride systems have been developed in the 2010s [1] for use in emergency or backup power units, i. e. for stationary applications.With the development and completion of the first submarines of the U212 A series by HDW (now Thyssen Krupp Marine Systems) in 2003 and its export class U214 in 2004, the use of metal hydrides for hydrogen storage in mobile applications has been established, with new application fields coming into focus.In the last decades, a huge number of new intermetallic and partially covalent hydrogen absorbing compounds has been identified and partly more, partly less extensively characterized.In addition, based on the thermodynamic properties of metal hydrides, this class of materials gives the opportunity to develop a new hydrogen compression technology. They allow the direct conversion from thermal energy into the compression of hydrogen gas without the need of any moving parts. Such compressors have been developed and are nowadays commercially available for pressures up to 200 bar. Metal hydride based compressors for higher pressures are under development. Moreover, storage systems consisting of the combination of metal hydrides and high-pressure vessels have been proposed as a realistic solution for on-board hydrogen storage on fuel cell vehicles.In the frame of the “Hydrogen Storage Systems for Mobile and Stationary Applications” Group in the International Energy Agency (IEA) Hydrogen Task 32 “Hydrogen-based energy storage”, different compounds have been and will be scaled-up in the near future and tested in the range of 500 g to several hundred kg for use in hydrogen storage applications.

Open-cathode PEMFC heat utilisation to enhance hydrogen supply rate of metal hydride canisters

In this paper, the hydrogen supply to an open-cathode PEM fuel cell (FC) by using metal hydride (MH) storage and thermal coupling between these two components are investigated theoretically. One of the challenges in using MH hydrogen storage canisters is their limited hydrogen supply rate as the hydrogen release from MH is an endothermic reaction. Therefore, in order to meet the required hydrogen supply rate, high amounts of MH should be employed that usually suggests storage of hydrogen to be higher than necessary for the application, adding to the size, weight and cost of the system. On the other hand, the exhaust heat (i.e. that is usually wasted if not utilised for this purpose) from open-cathode FCs is a low-grade heat. However, this heat can be transferred to MH canisters through convection to heat them up and increase their hydrogen release rate. A mathematical model is used to simulate the heat transfer between PEMFC exhaust heat and MH storage. This enables the prediction of the required MH for different FC power levels with and without heat supply to the MH storage. A 2.5-kW open-cathode FC is used to measure the exhaust air temperature at different output powers. It was found that in the absence of heat supply from the FC to the MH canisters, significantly higher number of MH canisters are required to achieve the required rate of hydrogen supply to the FC for sustained operation (specially at high power outputs). However, using the exhaust hot air from the FC to supply heat to the MH storage, can reduce the number of the MH canisters required by around 40% to 70% for power output levels ranging from 500 W to 2000 W.

INVESTIGATION OF EFFECTS OF HEAT RELEASE IN ELECTROCHEMICAL SYSTEMS AND THEIR USE IN TECHNOLOGIES FOR PRODUCTION OF ENERGY-INTENSIVE SOURCES FOR AIRCRAFT

The search for new, more energy-intensive types of fuel for the operation of the power plants of aircraft is the most important task in aviation. The unique fuel that has no analogues is hydrogen. The paper attempts to substantiate the technology of metal hydride hydrogen storage in electrochemical systems based on aluminum and its alloys as the most affordable materials from fossil metals, since the traditional methods based on the use of cylinders and cryostats are not effective in transport systems. It is shown that the volumetric storage of hydrogen in the porous structure of metals with the formation of hydrides on atomic bond defects is maximally suitable for the implementation of the system, eliminating the excessive pressure and the low temperatures. The porous structure of the material provides both a high degree of availability of the electrolyte solution to the electrode for the accumulation of hydrides in the entire volume of the metal, and not only on its surface, but also the conditions for the realization of the reduction effect that excludes the explosive nature of hydrogen extraction. The problem of increasing the temperature in the reaction zone, which sometimes causes a slowdown in the rate of certain stages of the electrochemical process, is considered. Using the example of galvanic chrome plating, it has been established that an increase in the temperature inhibits the process of the reducing of the metallic chromium. Therefore, the detailed account of the thermal effects in the electrochemical system allows us to determine the mechanism of the processes. The work revealed that the thermal effects arising at the cathode determine the kinetics of the hydrogen reduction processes during the formation of a hydride. And the thermal effects at the anode determine the kinetics of the formation of a porous structure in the metal. The authors proposed to use the principle of action associated with the transition to the technologies of the volumetric storage of hydrogen in a solid-phase system based on a metal hydride compound for the formation of a new class of aircraft - diaplan.

LIFE-CYCLE PERFORMANCE OF HYDROGEN AS AN ENERGY MANAGEMENT SOLUTION IN HYDROPOWER PLANTS: A CASE STUDY IN CENTRAL ITALY

The suitability of hydrogen as an energy management solution in a run-of-river hydropower plant inCentral Italyis evaluated from a life-cycle perspective. Hydrogen production at off-peak hours via electrolysis is considered, as well as potential hydrogen storage in metal hydrides followed by hydrogen use at peak hours for power generation using fuel cell technology. Hydropower generation and hydrogen production are identified as the subsystems contributing most to the nine evaluated impact categories (e.g., global warming, abiotic depletion and cumulative energy demand). The renewable hydrogen produced shows a more favourable life-cycle environmental and energy performance than conventional hydrogen generated via steam methane reforming. Furthermore, when enlarging the system with hydrogen use for power generation, the renewable electricity product shows a better life-cycle profile than conventional electricity for the Italian electrical grid. Overall, under life-cycle aspects, hydrogen is found to be a suitable energy solution in hydropower plants both as a hydrogen product itself (e.g., for transportation) and as a feedstock for subsequent power generation at peak hours.

Integration of metal hydride devices with polymer electrolyte fuel cells and electrolyzers for stationary applications

This paper presents the experimental results of the system integration of a fuel cell (FC), an electrolyzer and a metal hydride hydrogen storage and purification system. A pilot scale experimental power installation H2Smart with an electric power of 1 kW is developed, and the results of its operation in different regimes are presented. The problems of hydrogen desorption for the supply of FC and hydrogen sorption from the electrolyzer at the start are shown. Possible solutions of this problem are proposed.

Metal hydride technologies for renewable energy

Significant progress in the installation of renewable energy requires the improvement of energy production and storage technologies. Hydrogen energy storage systems based on reversible metal hydride materials can be used as an energy backup system. Metal hydride hydrogen storage systems are distinguished by a high degree of safety of their use, since hydrogen is stored in a solid phase, a high volumetric density of stored hydrogen, and the possibility of long-term storage without losses. A distinctive feature of metal hydride materials is the reversible and selective absorption and release of high-purity hydrogen. This paper presents experimental studies of LaNi5-based metal hydride materials with a useful hydrogen capacity of 1.0–1.3 wt.% H2with equilibrium pressures of 0.025 - 0.05 MPa and 0.1 - 1.2 MPa at moderate temperatures of 295 - 353 K for the hydrogen purification systems and hydrogen long-term storage systems, respectively. The applicability of metal hydride technologies for renewable energy sources as energy storage systems in the form of hydrogen is also shown.

Hydrogen storage in metal hydrides, synthesis and characterization

One of the keys to the implementation of the hydrogen economy is its safe and efficient storage. One of the most promising methods is metal hydrides. In this work, the influence of the mechanical grinding process on the properties of the TiCr1.1V0.9 alloy, specifically the absorption and desorption capacities, and structure of the hydride was studied. The maximum storage capacity was 3.2% wt. at a temperature of 40°C and pressure of 10bars, observing two types of hydrides TiCr1.8H5.3 with a body centred cubic (BCC) structure and TiH2 with face centred cubic (FCC) structure, which release hydrogen in two temperature ranges.

Influence of high thermal conductivity addition on PCT-isotherms of hydrogen storage alloy

High reaction heat of an interaction between intermetallic compounds and hydrogen along with low thermal conductivity of fine dispersed metal hydride powders lead to crisis phenomena in metal hydride hydrogen storage facilities. Thus investigations of composite materials with improved heat transfer are of great interest for development of hydrogen storage technologies. A composite material was made of powders of activated La0.9Ce0.1Ni5-alloy and copper. PCT-isotherms of hydrogen sorption and desorption was measured and compared for the composite and the pure alloy at temperature of 313, 333 and 353K. Values of ΔH and ΔS of the hydrogen sorption and desorption reactions were calculated, and temperature and pressure relaxation in the pure alloy and the composite material beds were studied. A significant difference between hydrogen storage behaviour of the pure alloy and the composite has been revealed.

Experimental investigations of thermal processes in the flow-throw hydrogen purification reactor

The paper presents experimental results of thermal processes investigations in flow type metal hydride hydrogen storage and purification reactor RSP-8(I). Thermal processes in the reactor during hydrogen separation from carbon dioxide are studied. Optimal operation parameters for hydrogen purification and performance efficiency of metal hydride reactor RSP-8(I) are defined experimentally. Investigations of heat and mass transfer inside a vertical metal hydride reactor RSP-8(I) with 1 kg of LaFe0.1Mn0.3Ni4.8 show considerable non-uniformity of pressure inside the bed. If the reactor is charged from the top, the hydrogen pressure at the bottom is lower by 0.2-0.3 MPa, which results in earlier occurrence of heat and mass transfer crisis.

Nanostructured Metal Hydrides for Hydrogen Storage.

Knowledge and foundational understanding of phenomena associated with the behavior of materials at the nanoscale is one of the key scientific challenges toward a sustainable energy future. Size reduction from bulk to the nanoscale leads to a variety of exciting and anomalous phenomena due to enhanced surface-to-volume ratio, reduced transport length, and tunable nanointerfaces. Nanostructured metal hydrides are an important class of materials with significant potential for energy storage applications. Hydrogen storage in nanoscale metal hydrides has been recognized as a potentially transformative technology, and the field is now growing steadily due to the ability to tune the material properties more independently and drastically compared to those of their bulk counterparts. The numerous advantages of nanostructured metal hydrides compared to bulk include improved reversibility, altered heats of hydrogen absorption/desorption, nanointerfacial reaction pathways with faster rates, and new surface states capable of activating chemical bonds. This review aims to summarize the progress to date in the area of nanostructured metal hydrides and intends to understand and explain the underpinnings of the innovative concepts and strategies developed over the past decade to tune the thermodynamics and kinetics of hydrogen storage reactions. These recent achievements have the potential to propel further the prospects of tuning the hydride properties at nanoscale, with several promising directions and strategies that could lead to the next generation of solid-state materials for hydrogen storage applications.