Hydrogen-oxygen fuel cell Subject

A transit bus fitted with hydrogen-oxygen fuel cells. The use of fuel cells could dramatically reduce urban air pollution. The conversion of chemical energy into electrical energy is one of the main subjects of this chapter. 

One new way in which electrolysis could be used is by simply electrolyzing sea water to hydrogen and oxygen and then converting these to water in a fuel cell, which would supply the energy to decompose more water. Such enormous amounts of energy are used in this process that to be competitive, the over-all efficiency of the electrolysis fuel cell combination would have to be over 99.5%. It is doubtful that this could ever be attained. Other schemes of electrolysis in which sodium and chlorine are removed are subject to the same disadvantage. 

One of the first fuel cell designs was low-temperature alkaline fuel cells (AFCs) used in the U.S. space program. They served to produce both water and electricity on the spacecraft. Some of their disadvantages are that they are subject to carbon monoxide poisoning, are expensive, and have short operating lives. The AFC electrodes are made of porous carbon plates laced with a catalyst. The electrolyte is potassium hydroxide. At the cathode, oxygen forms hydroxide ions, which are recycled back to the anode. At the anode, hydrogen gas combines with the hydroxide ions to produce water vapor and electrons that are forced out of the anode to produce electric current. 

Hydrogen would be burned in a fuel cell to power an electric vehicle. The only product would be water. This is the reverse of the electrolysis of water to produce hydrogen and oxygen. The system is not subject to the Carnot cycle, which limits... 

This chapter attempts to provide a critical review of the work carried out on alkaline fuel cell, which directly uses hydrogen rich liquid fuel and oxygen or air as an oxidant. The subjects covered are electrode materials, electrolyte, half-cell analysis and single cell performance in alkaline medium. Koscher et al. (2003) brought out elaborate review work on direct methanol alkaline fuel cell. Earlier Parsons et al. (1988) reviewed literature on anode electrode where, the oxidation of small organic molecules in acid as well as in alkaline conditions was considered. A review work on electro-oxidation of boron compounds was done by Morris et al. (1985). However, in this chapter use of three specific fuels, e.g., methanol, ethanol and sodium borohydride in alkaline fuel cell is discussed. 

---