Mazda has begun leasing RX-8 HYDROGEN RE in Japanese market from February 2006. The RX-8 HYDROGEN RE runs clean and exhausts the water vapor produced by hydrogen combustion. And because the car can also run on gasoline by switching the dual fuel system from hydrogen to gasoline, it can be driven places where hydrogen filling stations are not yet available.

This paper focuses the development of the hydrogen rotary engine, which has been tackled as a clean energy technology from the early 1990s.

The diesel engine has a diversified variety of uses such as power generation, marine vessels, and construction machinery. A hydrogen injection engine utilizes hydrogen as fuel in place of petroleum for such conventional diesel engines. As the fuel does not include carbon or sulfur, it is the clean engine that does not emit particulate matters, SOx, or CO₂. Except for its injection system it does not differ from a conventional diesel engine. Therefore, it has high reliability. It also has the merit of being able to use low purity hydrogen such as coke oven by-product gas, which includes methane and CO.

Using a single-cylinder engine of 100 kW with a high-pressure injection system of 30 MPa, combustion tests were conducted. As the results, stable self-ignition at high loads and a start-up with intake gas at room temperature by electric spark ignition were secured. The power generation efficiency was 49.2% (low heat value) at the rated load and that of 52.0 % (likewise) can be expected on the next generation engines. The NOx emission was reduced to 835 ppm (remainder O₂ of 0%) by exhaust gas recirculation. It can be decreased to 100 ppm (likewise) by catalytic reduction.

The characteristics of hydrogen have been reviewed to show that hydrogen is good as a fuel of automobiles. There are two mixture formations in hydrogen engines. One is external mixture. And the other one is internal mixture formation. These mixture formations show different characters in engine performance. By comparing the two mixture formations、 the author would like to show which one is better for automotive engines. Based on the result、 recent technologies and prospects have been discussed.

Reducing carbon dioxide emission and enhancing energy security are the most critical energy issues for construction of future energy systems. The hydrogen energy system is widely accepted as one of the most promising system options for solving such problems. Ministry of Economy, Trade and Industry (METI) of Japanese Government made public its revised introduction scenario of fuel cell vehicles (FCVs) and stationary fuel cells with a time frame of 2005 to 2030 in March, 2004. In this paper, we describe a scenario of the infrastructure construction for achieving the Government’s targets of FCV. And prospected future hydrogen costs being included, we have estimated the additional investments in the infrastructure.

Hydrogen permselective silica membranes were prepared by using a counter diffusion chemical vapor deposition method. H₂ permeances through silica membranes were over 8x10^-8 mol m^-2 s^-1 Pa^-1, and H₂/N₂ permeance ratios were over 500 at 873 K. Reproducibility of the silica membranes were 87%. Pore size of an alumina substrate was important parameter to obtain higher H₂ permeances. H₂ permeance was lager through a silica membrane deposited on a substrate having smaller pore size. Activation energies of H₂ permeance through the silica membranes increased with increasing the deposition temperatures. However, the membranes prepared over 873 K were not stable under steam at 773 K. A 3 membranes module was employed for the simultaneous multi membranes deposition of silica layers. H₂ permeance through the module was 5.0 x 10^-8 mol m^-2 s^-1 Pa^-1, and H₂/N₂ permeance ratio was 3200 at 873 K. The deposited silica membrane properties on the membrane module was similar to that deposited on a single membrane substrate.

Fermentative hydrogen production from starch and artificial food waste was studied by using a newly isolated mesophilic bacterium HN001. This bacterium could produce H₂ from starch directly. Effect of incubation temperature, cultivation pH and starch concentration were investigated using YNU anaerobic culture. The maximum H₂ production rate decreased along with the increase of temperature from 1.2L-H₂ L-culture^-1 h^-1 at 37℃ to 0.3L-H₂ L-culture^-1 h^-1 at 50℃. The production rate was also increased from 0.6L-H₂ L-culture^-1 h^-1 to 1.8L-H₂ L-culture^-1 h^-1 along with the increase of culture pH from 5.5 to 6.5. The maximum H₂ production rate did not increase linearly along with the increase of starch concentration but approached nearly fixed rate at 1.5L-H₂ L-culture^-1 h^-1 at over 1.5%-starch. H₂ yield decreased linearly along with the increase of starch concentration because of the increased lactic acid production. There were significant differences between cultivation with entrails and without entrails on the maximum H₂ production rate, accumulated volume of H₂ and metabolites production. This bacterium produced hydrogen approximately 66L at 37℃, pH6.0 from 1kg of wet artificial food waste containing cooked rice and frozen vegetables with entrails of fishes. The hydrogen production was also carried out at repeated batch cultivation.

In order to impart resistance against water vapor, a Laves phase alloy, (Ti_0.5Zr_0.5)(Fe_0.2Mn_0.8)_1.5, was encapsulated by ceramic cover layer derived from tetraethoxysilane (TEOS), which was one of the raw materials for sol-gel encapsulating method developed earlier. Although TEOS treated samples showed substantially no capacity loss under humidified hydrogen (partial pressure of water: 0.61 kPa), they showed unfavorable increase in apparent equilibrium pressures. Another problem to be resolved was lack of cyclic durability. Isotherms for TEOS treated samples approaches those for untreated ones through cycling. An improvement comprising introduction of rubber-like segments into sol-gel capsules brought about durability on cycling. Extrinsic loss of hydrogen capacity was minimized for a typical BCC alloy, Ti_0.1Cr_0.1V_0.8, which was assessed by a temperature swung hydriding-dehydriding cycles.

Experiments on the hydrogen gas explosion were performed to achieve the safe use of hydrogen energy, and the effect of explosion accidents on peripheral reinforced concrete (RC) structures was studied. Hydrogen gas with 37m³ in volume and 30% in volume concentration was detonated, and the response of the walls settled near the explosion center was measured in displacement, stress, cracks and damage situation. As the result, the damage mechanism of RC structures was studied. Fundamental data for the safety design of protective walls was obtained.

The purpose of our research is to construct the numerical model which can simulate the pressure characteristics and the damage of the RC-structure subjected to the hydrogen explosion. In order to validate a numerical model, we performed a hydrogen explosion tests performed. In part 1, we show the applicability of Autodyn2D to the phenomenon of hydrogen explosion. The computed results are compared with the experimental data. Next, the effects of the protect wall on the characteristics of the pressure propagation as a function of the height, the location of the wall and the height of the explosion source are clarified by using Autodyn.

In order to develop non-platinum cathode of polymer electrolyte fuel cells, TiO_xN_y which was prepared by a reactive sputtering was evaluated. The effect of heat treatment during sputtering and sputtering atmosphere on both the catalytic activity for oxygen reduction reaction (ORR) and the physical properties of TiO_xN_y has been evaluated. The solubility of TiOxNy was less than 2.5×10^-7 mol dm^-3 in 0.1 mol dm^-3 sulfuric acid at 30℃ and the cyclic voltammogram of TiOxNy did not change after hundreds of cycles. Therefore, TiO_xN_y which were prepared by a reactive sputtering had high stability chemically as well as electrochemically in acid solution. The ORR current density of heating specimens increased with increasing the heat treatment temperature during the sputtering. TiO_xN_y which were prepared under oxygen containing condition had higher catalytic activity than that prepared under nitrogen condition.

One of the dangers latent in the hydrogen society is that hydrogen has wider flammable range and smaller minimum ignition energy than hydrocarbons. Elucidating the mechanisms of turbulent combustion and establishing a model of turbulent burning velocity for hydrogen mixtures are expected to be developed for prediction and prevention of serious fire or explosion. In our previous studies, the local burning velocity of turbulent flames could be changed from the laminar burning velocity caused by the preferential diffusion effect, and play an important role in the turbulent burning velocity. The present study is performed to investigate directly the local flame properties of hydrogen premixed turbulent flames at the weak turbulence condition. Lean and rich hydrogen mixtures having nearly the same laminar burning velocity are prepared. Propane fueled mixtures are also examined for comparison. A two-dimensional sequential laser tomography technique is used to obtain the temporal statistical relationship between the flame shape and the flame displacement. In order to examine the local burning velocity, the local flame displacement velocity SF is quantitatively obtained as the key parameters of the turbulent combustion. The obtained SF is also discussed by the concept of the Markstein number as well as the preferential diffusion effect.