Hydrogen, energy conversion production

Ti02 and Ti02-based films are extensively studied as materials for light-to-energy conversion, production of hydrogen and cleaning of environments and are fabricated by the sol-gel method. 

Keywords chemical energy conversion energy storage chemical heat pump separation hydrogen production reaction equilibrium... 

To calculate the amount of hydrogen produced by electrolysis powered from a wind energy conversion system within a year, the efficiency of the AC/DC (or DC-DC ) conversion 0/c) and the energy consumption of the electrolyzer (ecel) per newton cubic meter of H2 production need to be defined. The efficiency of a standard AC/DC converter ranges from 80% to 95% [41]. High values of t]c occur in the conversion of large amounts of power. Typical values of ecel range from 5 to 6 kWh/Nm3. 

Heat from all the hot exhaust gas streams is used for steam generation to drive the steam turbine. Thus, the final products from the GE fuel-flexible process are pure hydrogen from the first reactor, C02 from the second reactor, and heat for electricity production from the third reactor. A portion of the solids in the chemical loops needs to be purged to avoid ash accumulation and maintain solid reactivity (Rizeq et al., 2002). The overall energy conversion efficiency for the GE fuel-flexible process is estimated to be 60% (Rizeq et al., 2003). 

At the exit of the WGS reactor, the reacted CaC03 particles are captured by a high-temperature cyclone and the spent solids are then sent to a rotary calciner to thermally decompose the CaC03 back to CaO at temperatures between 660°C and 900°C with pure C02 formed in the outlet gas stream. The pure C02 gas can be economically compressed, cooled, liquefied, and transported for its safe sequestration. Hydrogen can be used for various energy conversion systems or hydrogen-enriched fuel production without any further low-temperature cleanup requirement. 

The rate of H2 production by one unit of photobioreactor s volume is not useful for estimation of strain capabilities or for measurements of efficiency of light energy conversion. However, it is useful unit of measurements for optimization of hydrogen production by particular photobioreactor. From practical point of view it does not matter how much cells are in the photobioreactor or how much hydrogen is produced by one unit of illuminated surface. The rate of hydrogen production by the whole photobioreactor is of first importance. For a comparison of different photobioreactors it is better to express rate of hydrogen photoproduction per unit of its volume. So, it is practical unit for estimation of actual hydrogen photoproduction. 

The scope of this chapter is to present a concise and fundamental overview of the relationship between modem catalysis and chemical reaction engineering through one of the topics that will certainly be present among the future directions in both fields production of hydrogen fuel from fossil and renewable energy sources and its use in the fuel cells-based energy conversion technology. 

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