This article describes the importance of hydrogen production technologies and gives the brief review on the articles collected for this special fearture reports.

The technical present status of hydrogen production process using IS thermochemical cycle was introduced. This process is experimentally investigated in Japan, USA, Germany, France, Italy, India, China and Korea. Japan Atomic Energy Agency succeeded in consecutive hydrogen production as a proof examination. The trend of the research and development about the reactions, separation technology, device materials and the process equipment were reported. Thermochemical ammonia production cycle was also introduced. This new cycle is named ISN cycle which was modified from IS cycle in order to produce ammonia from water and nitrogen.

Tokyo Gas and other gas companies have developed the hydrogen production catalysts and fuel processing systems (FPS) for a lkW class residential PEFC system. High efficiency and compactness of FPS have been achieved by the integration of some hydrogen production processes. In addition, the durability for about ten years has been confirmed by the demonstration of 4,000 daily start and stop (DSS) operations and the accelerated tests for 40,000 hours.

A solid oxide fuel cell (SOFC) system can offer high efficiency. Moreover, it is a rather simple process in comparison to polymer electrolyte fuel cell (PEFC) system. The fuel processor for PEFC needs water-gas shift (WGS) and preferential oxidation (PROX) processes to remove CO that poisons the Pt anode. In contrast, SOFC does not need CO removing processes because it can use CO as a fuel source. Generally, there are three types of reactions to generate hydrogen from hydrocarbon for fuel cell, steam reforming (SR), partial oxidation (POx), and autothermal reforming (ATR, combined SR and POx reaction). SR or ATR is effective to achieve high electrical efficiency because it can balance the heat between the heat required for the endothermic reaction of reforming reaction in reformer and the heat produced by fuel cell generation. At the start-up, the exothermic reaction such as POx or ATR is useful for heating the reformer. In this paper, the features of SOFC type residential fuel cell system in comparison to PEFC type residential fuel cell system and the reforming technology used for SO FC system are explained.

The state-of-art and future prospects of BioHydrogen are overviewed, targeted on photosynthetic microorganisms (photosynthetic bacteria, cyanobacteria and green algae as main objects. We describe here our recent results, mainly hydrogen production with sugar by co-culture of photosynthetic bacteria and anaerobic bacteria. Recent efforts of genetic alteration to enhance hydrogen production in these microorganims are briefly introduced.

Dissemination of fuel cell vehicles (FCV) is one of the key issues for preservation of the environment on earth, especially for reduction of greenhouse gasses. Standardization of those technologies is important to develop the market growth of FCV. This paper reviews the progress of international standardization for the hydrogen fuel quality of proton exchange membrane (PEM) fuel cell applications for road vehicles, and indicates the prospect of the further standardization. The technical specification ISO/TS14687-2 which was for the FCVs introduction stages has been published in 2008. It is now revised for the international standard and is expected to be published in the middle of 2012. This international standard is also going to be revised because some of the items need to be reviewed for the mass production stage which will come in years before next decade.

Coal is an important fossil fuel because of its abundancy and price stability. However, coal produces more CO₂ than other fossil fuels and has disadvantage from. the standpoint of global warming. Gasified coal contains both H2 and CO, and by shift reaction CO is converted to CO₂. Hence, H₂ and CO₂ can be effectively produced from. coal when CCS (Carbon Capture & Storage (or Sequestration)) is socially accepted and commercialized, and hydrogen production by coal will be even more promising.

Experiments of the dispersion for the hydrogen gas from high pressure storage tank have been conducted to investigate the safety of the hydrogen station. For the small amount dispersion from pin-hole smaller than 2mm diam., hydrogen concentration could be arranged by the simple expression in which the non-dimensional distance is defined by the nozzle diameter and hydrogen density. For the large amount dispersion from the nozzle larger than 5mm diam., the unsteady numerical simulation was conducted, because the discharged hydrogen from high-pressure tank makes the supersonic jet. The numerical calculation method which requires not so long time could be proposed, and evaluated the validity of the method by comparing the calculation results with experimental data. Furthermore, the experimentally measured dispersion rate was different from the theoretical value calculated with the assumption that the hydrogen was ideal gas and expanded isentropically. From the one-dimensional analysis including the real gas effect and numerical simulation that reproduced the shape of the nozzle, it was concluded that the real gas effect doesn’t have much effect on the decrease of the mass flow rate and it is mainly due to the pressure loss by the shape of the nozzle.

In this article, the mid-long term energy balances in Japan taking account of the Great East Japan Earthquake was studied. Three major risks that may occur around 2050 were considered. The major risks were low acceptance for nuclear, CO2 constraint and shortage of oil and gas. It was concluded that the development of various energy technologies such as energy saving, renewable, nuclear and fossil fuels should be promoted to manage the major risks especially for the long-term energy balances. Hydrogen related technologies have a large potential to contribute to manage the major risks.