Hydrogen production sources

Table 7.1 World Hydrogen Production Sources Today...

Figure 7.1 Feedstock share of global hydrogen production, (Source Reproduced with permission from Ref [I], Copyright 2013, Pergamon)...

Chapter 9 provides an overview of mitigation strategies that are divided into three sections (1) mitigation of hydrogen impurities in hydrogen production sources, (2) mitigation of impurities in the fuel cell system, and (3) reducing the impact of impurities on fuel cells. 

In contrast to fossil energy resources such as oil, natural gas, and coal, which are unevenly distributed geographically, primary sources for hydrogen production are available virtually eveiywhere in the world. The choice of a primary source for hydrogen production can be made based on the best local resource. 

Lewin and Cohen (1967) determined the products of dediazoniation of ben-zophenone-2-diazonium salt (10.42, Scheme 10-77) in five different aqueous systems (Table 10-7). About one-third of the yield is 2-hydroxybenzophenone (10.46) and two-thirds is fluorenone (10.45, run 1) copper has no effect (run 2). On the other hand, addition of cuprous oxide (run 3) has a striking effect on product ratio and rate. The reaction occurs practically instantaneously and yields predominantly fluorenone. As shown in Scheme 10-77, the authors propose that, after primary dediazoniation and electron transfer from Cu1 to 10.43 the sigma-complex radical 10.44 yields fluorenone by retro-electron-transfer to Cu11 and deprotonation. In the presence of the external hydrogen atom source dioxane (run 12) the reaction yields benzophenone cleanly (10.47) after hydrogen atom abstraction from dioxane by the radical 10.43. 

Because coal is an important economical source for production of hydrogen, developing new technologies to improve the efficiency of hydrogen production is an important priority. Some new approaches for producing hydrogen from coal are discussed in the following section. 

Demirbas, A., Hydrogen production from biomass by the gasification process. Energy Sources 2002, 24, 59. 

Hacker, V. Fankhauser, R. Faleschini, G. Fuchs, H. Friedrich, K. Muhr, M. Kordesch, K., Hydrogen production by steam-iron process. Journal of Power Sources 2000, 86, 531-535. 

Source Based on Saito, Y., Hodoshima, S., Shono, A., and Otake, K., Hydrogen production from cyclohexane and hydrogen production. Proceedings of 9th Asian Hydrogen Energy Conference, Tokyo, 2007. 

The new frontiers of hydrogen energy systems described in this paper will be PEM-electrolysis combined with renewable energy sources, biolysis with use of biological methods based on the genetics, and mechanolysis combined with any moving phenomenon and object, in hydrogen production area. 

Glucose, glycerol, sucrose, starch, acetate, malate and lactate were examined for the effect of carbon sources on the hydrogen production and the effects of light intensity were also examined under the different irradiances, such as 0, 3, 7, 15, 30, 50 and 110 klux/m2, by adjusting the distance between the light source and the samples of Rb. sphaeriodes KD 131 cultures. 

When acetate was used as a carbon source, the initial pH 6.8-7.0 was increased to 9.2-9.4 by the wild-type strain but 7.4-7 6 by the mutant strain. The increase in pH by the wild-type strain might be due to the accumulation of PHB in cells. Khatipov et a/. [11] also found that in nitrogen-deprived cells, the initial medium pH 7.5 increased to 10 and at the same time, PHB accumulation increased twice as compared to cells grown from an initial pH 6.8. Hydrogen production in this case decreased more than eightfold. 

Malate and lactate were better carbon sources for the hydrogen production than starch, sucrose and glycerol for the wild type and mutant strains. 

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