Hydrogen occluding alloys are finding their practical positions in various application fields, after they resolved sophisticated issues on regulations for the carriage and storage of dangerous goods. The present situation of stationary hydrogen storage using the alloys was overviewed, and the widely spreading scope of the materials was discussed.
Hydrogen storage alloys are able to store a large amount of hydrogen safely and easily. Therefore, hydrogen storage alloys have received much attention for energy conversion and storage material. The application field of hydrogen storage alloys as a functional material covers a wide range, and the alloys were already commercialized for Nickel-metal hydride battery as a negative electrode material. Recently, the hydrogen energy system consisted of renewable energy, batteries, electrolyzer, hydrogen storage alloy tank and water tank, and fuel cells was developed. Electricity generated from the renewable energy is inputted to the electrolyzer for electrolyzing water and producing hydrogen directory. Hydrogen is stored in the hydrogen storage alloy tank which contains the hydrogen storage alloy supporting much improved high-density storage. This new hydrogen storage alloy tank is less than one-tenth of the size of the conventional type hydrogen gas tank, and most suitable model for use even in small spaces.
The nanostructured FeTi alloy produced by mechanical alloying exhibited a high rate of the initial activation compared with an untreated polycrystalline FeTi alloy. A ball-milling system was developed for a mass production of the nanostructured FeTi (n-FeTi) alloy. Using this system, an amount over 300 kilograms of the n-FeTi alloy can be produced by a butch. The n-FeTi alloy exhibits high rates ofthe initial activation and cyclic hydrogen absorption-desorption reactions, and a high cyclic stability at room temperature under 1MPa of hydrogen gas with a purity of 99.99%. The produced n-FeTi alloy was certified as a non-hazardous material under the Fire Defense Law of Japan. A manufactured hydrogen storage tank containing of the produced alloy was examined in terms of hydrogen absorption-desorption rates, and renewable energy storage performance. Obtained results showed a high availability of the tank in the practical storage of renewable energy.
Metal hydrides can absorb large quantities of hydrogen at room temperature and ordinary pressure. Metal hydrides become pulverized with absorbing and desorbing hydrogen, and this phenomenon sometimes causes the tank transformation owing to the uneven distribution of powders in the tank. Our metal hydride, named “Hydrage™” was made using a technique of combining the metal hydride powders with polymer materials preventing decrease of the hydrogen absorption and desorption rate. With this technique, the metal hydride powders were immobilized, and strain of the tank was reduced. Furthermore, “Hydrage™” enabled uniform dispersion of the metal hydride powders. These effects achieved high filling density in the tank relative to that of conventional metal hydride tank. As an application of “Hydrage™”, we made a large MH tank system which could store around 100kg of hydrogen. Dimension of one metal hydride tank system with a capacity of 100 kg is 1.8m in width, 3.1m in length, and 2.1m in height. This system consists of 9 cylindrical tanks. Metal hydride tank system, which can store a large amount of hydrogen safely and compactly, has the potential to become popular with various applications in the future.
Development research on Metal Hydrides was actively conducted in Japan from the 1970s as a dream new material that hydrogen storage density is comparable to liquid hydrogen. However, people other than limited researchers also got metal hydrides in the 1980s, and now they can actually use them. In the early 1980’s, it became a big opportunity that aluminum Canister filled with Metal Hydride called AHT 5 of Billings became available in Japan as well. I think the Metal Hydride Canister is the simplest and clearest one as a usage form of the Metal Hydride. However, when trying to put Metal Hydride Canister into practical use in Japan, it is necessary to overcome various obstacles such as laws and regulations. I would like to explain the situation around here in this paper.
In this paper, hydrogen storage alloys are considered to be a material for hydrogen compression by means of its thermodynamic properties. The hydrogen absorbed in a hydrogen storage alloy at room temperature can be drastically increased with the increase of temperature. Actually, the well known-“van’t Hoff equation” shows that logarithmic value of pressure is depending on the inverse of temperature. Eventually, we have succeeded in the compression from around ambient pressure up to 82 MPa by means of Ti-Cr-V alloy and Ti-Cr-Mn alloy only by the heat below 300°C.
Binary metal-hydrogen systems were reviewed on the basis of thermodynamics and inorganic chemistry, and typical pseudo-binary alloy-hydrogen systems were overviewed in terms of practical interests. Van’t Hoff plots comprising both alloys and their component metals clearly indicated the progress of researches and developments of hydrogen storage materials.
Aichi Synchrotron Radiation Center (AichiSR) has been operated for industry users and academic users since 26th March 2013 as the eighth synchrotron radiation facility in Japan. The use shifts (1 shift = 4 hours) of all beam-lines of AichiSR were over 1,600 and the industry users accounted for about seventy percent in 2015. Outline of synchrotron radiation accelerators, beam-lines, and facility management are presented. The in situ measurements by powder X-ray diffractions during hydrogen absorption and desorption process of pure palladium powder and XAFS measurements of magnesium hydride by soft X-ray are described.