Remote power supply 223 hydrogen

Finally, the techno-economic analysis of specific case studies of already existing autonomous power systems revealed that such systems can be a significant short- to medium-term market niche. In the presented case studies it was shown that specific hydrogen-based autonomous power systems can be financially competitive to respective power systems using conventional power-generation equipment, even in the short term. Moreover, the introduction of hydrogen in autonomous power systems has significant environmental benefits and it can contribute to the security of power supply of remote communities. 

Flow cells are ideal for stors e systems in remote locations. Vanadium redox systems, for instance, deliver up to 500 kW for up to ten hours. Zinc-bromine systems have been produced for 50-kWh and 500-kWh systems to reinforce weak distribution networks or prevent power fluctuations. Hydrogen fuel cells can potentially do almost anything a battery can do provide backup power, perform power leveling, run handheld devices, and supply primary or auxiliary power to cars, trucks, buses, and boats. In many cases they are more efficient than petrochemical fuels. A hydrogen fuel cell in a vehicle that uses an electric motor, for example, can be 40 to 60 percent efficient, compared with the 35 percent peak efficiency of the internal combustion engine. 

In practice, the suitability of a reaction system is determined by the kinetics of the reaction, which depends on temperature, pressure of gases, electrode polarization, surface area of electrodes, and presence of a catalyst. A fuel cell that is thermodynamically and kinetically feasible must be considered from an econonuc viewpoint before it is accepted. Thus, since hydrogen, hydrazine, and methanol are too expensive for general application, their use in fuel cells has been limited to special cases. Hydrogen has been used for fuel cells in satellites and space vehicles, in which reliability and lightness are more important than cost. Hydrazine fuel cells have been used in portable-radio power supplies for the United States Army because of their truly silent operation. Methanol fuel cells have been used to power navigation buoys and remote alpine television repeater stations because such power systems are comparatively free from maintenance problems over periods of a year or more. The polarization at the electrodes of a fuel cell is the most important single factor that limits the usefulness of the cell. The various polarization characteristics for a typical fuel cell are plotted separately as a function of current density in Fig. 9.11. 

Power plants using fuel cells can now take the place of the present polluting coal or oil-based (indirect) electricity-producing plants. However, in a further development, it would be possible to extract COz from the atmosphere, and H2 from solar-driven electrolysis, to produce methanol with zero net injection of C02 into the atmosphere. These plants would at first ran on hydrogen from these fossil fuels, the attraction being the reduction of pollution and the increase in the conversion efficiency. To what extent the latter two commodities would be supplied from remote sites, or collected onsite at... 

The two applications for which this reactor is being developed viz., as a source of process heat for hydrogen production by splitting water and as a compact nuclear power pack to supply electricity in remote areas unconnected to the grid system, have a large potential market, especially in developing countries. 

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