The nickel hydrogen batteries using hydrogen storage alloy have great potential for the commercial use. However, the nickel hydrogen battery having large capacity is not commercially available, so that there are few reports on its characteristics. Therefore, we carried out a trial fabrication of the nickel hydrogen batteries. This time, we made the nickel hydrogen battery using carbon conductive enhancement instead of copper powder. For the cycle life times, the capacity has been kept 75% of the initial state after 170 cycle times. Although the cycle time characteristics were the same as the battery using copper powder enhancement, the energy density was improved from 46Wh/kg to 50Wh/kg.

The hydrogen oxidation reaction has been studied between 30 and 70℃ by means of a Pt microelectrode attached to polymer electrolytes of different equivalent weight value. Diffusion coefficients and concentration were obtained by the chronoamperornetry and the Cottrell equation. The limiting current and the diffusion coefficient increased with increase of the cell temperature. On the other hand, the solubility of hydrogen decreased with increase of temperature. It was found that the diffusion coefficient is one order higher than that of oxygen. No large difference in hydrogen overpotential, hydrogen diffusion and hydrogen dissolution was observed for the membranes of different equivalent weight.

Important roles of hydrogen as energy resources of fuel cells and combustion turbines or chemical reagents for reducing carbon dioxide exhausted from factories prompted us technology developments for long-term storage and long-distance transportation of hydrogen, where the decalin/naphthalene pair was adopted as an effective hydrogen carrier. Under boiling and refluxing conditions, catalytic dehydrogeno-aromatization of decalin under mild reaction conditions was accomplished efficiently with carbon-supported metal catalysts in liquid-film states. An equilibrium-exceeding one-path conversion (24.6%>1.2% at 210℃) was attained due to superheated catalytic active sites.

To use kelps as a substrate for fermentative hydrogen production by Enterobacter aerogenes strain E.82005, hydrogen evolution rates and yields from mannitol were measured under various salt-concentration cultures Under non-salt condition, they were 13 mmol per litter culture per hour and 1.6 mol H₂ per mol mannitol, as compared with these, under salt condition 1%, 2%, and 3%, they were 9.9 and 1.5, 4.3 and 1.2, and 3.0 and 0.9, respectively. From these results, we concluded that the production of hydrogen is suitable under non-salt condition, but lower salt condition than seawater especially around 1% i s allowable for practical production of hydrogen. The higher yield of H₂ from mannitol than from glucose was clearly shown from the mass balance between evolved H2 and calculated H2 from metabolite.

Several samples of steam reforming catalysts were picked from a pressurized phosphoric acid fuel cell demonstration power plant after operation of 23,140 hours. From the chemical and physical properties of the catalysts, it was shown that the activity of each catalyst was lost mainly due to sulfur poisoning at the inlet of the catalyst bed. At the outlet of the catalyst bed, however, the activities of reforming catalysts were maintained over the 23,140 hours operation.

A redox reaction pair of acetone hydrogenation/2-propanol dehydrogenation is used as a thermoregenerative fuel cell by converting low-quality heats into electric energy directly, where catalytic dehydrogenation of 2-propanol takes place at 90°C and is coupled with the fuel cell consisiting of hydrogen/acetone electrodes. At the positive electrode, catalytic reactions proceed among acetone, proton and electron. Carbon-supported ruthenium and ruthenium-platinum composite catalysts prepared by an impregnation method exhibted certain extents of electricity generation. Catalyst design for better fuel cell electrodes is proposed from a viewpoint such that vacant d-orbitals of the positive-electrode catalyst metals should possess proper lobe extentions and energy levels in order to have large adsorption abilities toward acetone and to yield 2-propanol by facile C-H bond formation.

JAERI(Japan Atomic Energy Research Institute) has long term projects for R&D of nuclear heat utilization technologies with HTTR(High Temperature engineering Test Reactor; thermal out-put, 30MW out-let temperature 850℃), which reactor is planted to be critical in 1998. In these technologies, mass hydrogen production by steam reforming, high efficiency electrical generation system, IS process and advanced new processes are included. In present paper, recent progress of these new technologies for high temperature nuclear energy in JAERI are reported.

An 1kW class methanol reformer which generates hydrogen gas from methaol as a raw material fuel and supplies it to Polymer Electolytc Fuel Cell (PEFC) is developed for transportable application. Original design such as plate-stack configuration and two-stage selective oxidation of carbon mono-oxide (CO) attain the prominent performance of compactness, high methanol conversion (1~3kW) and high combustion efficiency and low enough CO concentration (less than 10ppm) in the reformed gas.

With the Fuel Cell Technology, Daimler-Benzis opening the door to an automotive future without emissions and increasing energy costs: Fuel cells, which process hydrogen as “fuel”, provide an ideal range for municipal and shuttle traffic―at airports, for example. The electric drive is clean, quiet and comfortable. With internal combustion engines, utilization of the fuel is meeting natural limits. In fuel cells, by contrast, the chemical reaction between air and hydrogen produces electric energy, water vapor and heat without such restrictions.

The development of photocatalysts for H₂ production by water splitting was reviewed. TiO₂ photocatalysts have been studied extensively for a long time. ZrO₂, Ta₂O₅, KTaO₃, NaTaO₃, BaTa₂O₆, etc. have recently been found as new photocatalyst materials except for titanates. These materials possess bulk structures which do not consist of any characteristic secondary structures. In contrast, photocatalysts with microporous structures as secondary structures have been reported. K₄Nb₆O₁₇ and K₂La₂Ti₃O₁₀ with layered structures possess high activities. Na₂Ti₄O₁₃ and BaTi₄O₉ with tunnel structures and K₃Ta₃Si₂O₁₃ with a one dimensional structure are also active materials. These photocatalysts respond to only UV light because of their large band gaps. Some visible light driven-photocatalysts were developed in order to aim at an artificial photosynthesis. Under visible light irradiation, Cu-ZnS and BiVO₄ show high activities for H₂ or O₂ evolution from aqueous solutions. On the other hand, some metal oxides such as Cu₂O decompose pure water into H₂ and O₂ in stoichiometric amounts cvcn under dark condition when they are strongly stirred in liquid phase water. The mechano-catalysisis a novel reaction for water splitting.

Hydrogen production from water using inexhaustible solar light, which is considered to be an artificial photosynthesis reaction, is one of dream technologies for human beings. Here, recent progress in photocatalytic water splitting was introduced. First, it was shown that Na₂CO₃ addition method was very useful to produce H₂ and O₂ from water stoichiometrically using simple semiconductor photocatalysts such as Pt/TiO₂. Using this method, solar hydrogen production was demonstrated for the first time. Then, a two-step water splitting system, which was similar to Z-scheme of photo-synthesis, was newly proposed in order to utilize visible light.

Direct hydrogen fuel cell vehicles and methanol fuel cell vehicles are being developed as a potential alternative to the internal combustion engine vehicles. Fuel choice for fuel cell vehicles is a matter of primary concern now in automobile industries. There are many technical and cost issues for the development of commercial vehicles. Fuel choice will affect a strategy for market introduction of hydrogen refueling stations. A local natural gas reforming station and a local PEM electrolyzer station have a high potential of market introduction in Japan. These two refueling stations will be developed and demonstrated in the WE-NET program by the year 2002.