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Hydrogen has difficulties in handling in a fuel cell vehicle, and has a fault with taking a big space there. The authors have proposed a hydrogen generation system using ammonia as a liquid fuel for fuel-cell electric vehicles. Ammonia has an advantage not to emit greenhouse effect gases because it does not contain a carbon atom. Hydrogen content of ammonia is 17.6 wt% and hydrogen quantity per unit mass is large. Ammonia can be easily dissociated to hydrogen and nitrogen by heating. Therefore, ammonia is an attractive hydrogen supply source for fuel cell vehicles. The ammonia hydrogen generation system of this study consists of a vaporizer, a heat exchanger and a cracking reactor with a separator. Ammonia is heated with the heat exchanger and sent to the cracking reactor, after it is evaporated through the vaporizer from the liquid ammonia. The ammonia is cracked to hydrogen and nitrogen with an appropriate catalyst.

Dimethyl ether (DME) has received a lot of attention recently as a possible alternative to diesel engines for little environmental effects and stable distribution. DME can be made from various resources in large quantities and easily transported. It has the same cetane number as that of diesel fuel and emits no smoke from diesel engines. Moreover it is also expected to be a fuel for fuel cells because much hydrogen can be obtained by steam reforming. This paper focuses on a hybrid power system for commercial vehicles with a diesel engine and a fuel cell fueled with DME as a single fuel. The system obtains a driving power by diesel engines with DME combustion and at the same time generates electricity by a fuel cell with hydrogen generated from DME reforming. The electric power can be supplied to a refrigerator or batteries. The total energy loss will be less in DME reforming by recovering the exhaust heat from the engine.

In this paper, the authors have described a fuel-cell electric vehicle for trial purposes with the hydrogen generation system fueled with ammonia for compact vehicles. The system consists of a dissociator with Ruthenium/Alumina catalyst, a heat exchanger and an ammonia separator to remove residual ammonia. The dissociation system compactly unifies the heat exchanger and the dissociator to effectively rise the temperature of the system by installing some alumina balls just before catalyst. Therefore the system can be small in size enough to be installed on-board in the vehicle. The cruising time is about 160 minutes in the system. If the concentration of residual ammonia in the dissociated gas becomes 13 ppm or more, the residual ammonia will poison the proton exchange membrane (electrolyte) of the fuel cell, and cause the fuel cell to decrease the output.

Fuel without carbon is essential effective in preventing global warming by carbon dioxide. Hydrogen has no carbon and can be made also from the resources such as nuclear energy or renewable energies. However hydrogen is lack of portability for automobiles because of its difficulty in liquefying. Ammonia also has an advantage in terms of global warming because of carbon-free fuel. A hydrogen generation system fueled with ammonia from urea for a fuel-cell electric vehicle is described in this paper. In ammonia, the handling must be careful of safety specifically because toxicity of ammonia affects a human body and a fuel cell. On the other hand, urea can be easily changed into ammonia and dealt with safety. The license for handling of urea is unnecessary, and there are also achievements as a NOx reducing agent for diesel engines. The authors have proposed urea as a hydrogen carrier via ammonia.