Demand for hydrogen is rapidly growing in the current environmental approach to meeting requirements of extremely low-sulfur and increasingly light fuels. The trend toward increase in hydrogen demand is expected to be accelerated with development and commercialization of fuel cell and synthesis fuel oil which are both attracting widespread attention as clean energy technologies.
The steam reforming process, which has been used as the most popular industrial hydrogen production technology, is outlined here. The life cycle assessment, which rates net emissions of greenhouse gases from the steam reforming process, is also introduced. In addition, efficient methods for increasing the capacity of the steam reforming process are explained in the light of increasing calls in recent years for revamping hydrogen plants.

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Hydrogen energy system is one of the solutions for the global issue of greenhouse gases emission. The hydrogen supply chain system i. e. manufacturing, transportation and storage shall be discussed for the development of hydrogen Society. From this standpoint, thermal efficiency and CO₂ emission of both hydrogen energy system and fossil energy system are evaluated in the “Well to Wheel” and “Well to Bus”.

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To solve problems of the global environment, the realization of hydrogen economy is now in strong demand among the international community. Four key technologies are necessary for hydrogen economy:hydrogen production, transportation, storage, and utilization. In this paper, the current status with respect to hydrogen storage technologies, which include high-pressure storage, liquid hydrogen, metal hydrides, and other storage materials, is summarized.
In addition, one of the promising hydrogen storage materials, metal hydride, is described in detail. Hydrogen ab⁄desorption reactions of metal hydride are associated with heat. Heat management, as well as compactness and lightweight, therefore, is required for metal hydride hydrogen storage. In order to optimize the balance between compactness and high performances (especially the hydrogen flow rate) of the storage system, appropriate heat management has to be implemented in the design of metal hydride storage tanks.
A hydrogen refueling station, a fuel cell-powered underwater vehicle, and a fuel cell-powered cell phone are described as application examples of metal hydride storage in Japan.

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Hydrogen energy will solve the global environmental issues. Fuel cell vehicles'commercialization will require the hydrogen supply infrastructure. LH₂ (Liquid hydrogen) would be the most promising medium of transporting and storing hydrogen as infrastructure. The large-scale LH₂ system would be similar to the existing LNG system.
A LH₂ container, which intends for multi-modal large scale transportation of LH₂ by road, by rail or by sea, will be one of important equipments for realizing the economical and efficient LH₂ systems. Thermal behavior and sloshing of a LH₂ container, which differ from those of a stationary tank, will influence the boil off gas loss and the pressure rise of the closed vessel. This paper reviews LH₂ systems and their features, and also describes an example of analytical results of sloshing of a LH₂ container.

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Activities of Cryogenic Materials Working Group (Task 10) in the WE-NET program are introduced with emphasizing on mechanical properties of metallic structural materials used in liquid hydrogen and compressed gaseous hydrogen. Regarding the evaluation of properties in liquid hydrogen, mechanical tests were conducted mainly using the newly designed and installed facilities for mechanical testing in liquid hydrogen. Austenitic stainless steel plates of 5mm in thickness and their welds processed with TIG, MIG and FSW showed excellent mechanical properties at cryogenic temperatures, while the thicker weld metals processed with multi-layer deposition sometimes exhibited lower toughness in cryogenic circumstances. Regarding gaseous hydrogen, SUS304L showed clear hydrogen environmental embrittlement (HEE) even at room temperature, while SUS316L showed no HEE at room temperature although some ductility decrease was recognized at low temperatures. All kinds of steels tested, including plain steel, low-alloyed steels and stainless steels, exhibited considerable hydrogen absorption when the specimens were exposed at 54°C for 1000h in compressed hydrogen gas at 27MPa pressure. In case of stainless steels, plastic deformation at room temperature enhanced this tendency.

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Hydrogen is expected to play an important role in the transportation sector for fuel cell vehicles (FCVs) . The infrastructure of hydrogen refueling stations from low cost sources like natural gas is necessary to the successful transition toward hydrogen-based society. Osaka Gas has successfully demonstrated the on-site hydrogen production system with low-pressure reformer at the first hydrogen refueling station based on steam methane reforming (SMR) in Japan under World Energy Network (WE-NET) Project. We also developed a new compact hydrogen production system with medium-pressure reformer for hydrogen infrastructure as well as industrial use. The basic unit generates 30Nm³⁄h pure hydrogen (99. 999%) , and all components are packaged on one skid. Our development effort realized to reduce 50% installation area, 50% capital cost and 30% operating cost compared with our conventional system.
The paper will describe our conventional on-site hydrogen production system based on SMR that was installed at the WE-NET hydrogen refueling station in Osaka, and subsequently focus on the detail of our new compact hydrogen production system for wide variety of applications.

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