High-temperature water splitting

High-temperature splitting of water occurs at about 3000°C. At this temperature, 10% of the water is decomposed and the remaining 90% can be recycled. To reduce the temperature, other processes for high-temperature water splitting have been suggested, such as (Marban et al., 2001) ... 

High-Temperature Water Splitting Using Nuclear Energy.601... 

High-temperature water splitting (a thermochemical process) is a long-term technology in the early stages of development. High-temperature heat (500°C-2000°C) drives a series of chemical reactions that produce hydrogen. 

High-temperature water splitting is most suitable for a large-scale and centralized production of hydrogen even though semi-central production from solar-driven cycles might be possible. 

Balachandran, U., Wang, S., Dorris, S.E., and Lee, T.H. (2004) Hydrogen production by high temperature water splitting using electron conducting membranes. US Patent Appl. 2004/ 0098914 Al. 

Hydrogen can be produced from splitting of water through various processes ranging from water electrolysis, photo(solar)-electrolysis, photo-biological production to high-temperature water decomposition. 

Multistep Thermochemical Water Splitting. Multistep thermochemical hydrogen production methods are designed to avoid the problems of one-step water spHtting, ie, the high temperatures needed to achieve appreciable AG reduction, and the low efficiencies of water electrolysis. Although water electrolysis itself is quite efficient, the production of electricity is inefficient (30—40%). This results in an overall efficiency of 24—35% for water electrolysis. 

High temperature (often exceeding 1000 K) drives the endothermic chemical reactions. Multistep cycles for water splitting are used because very high temperatures are required before an appreciable amount of water decomposes in single-step cycles. Thus, in one or more subsequent chemical reactions, the intermediary compounds can be recovered to the original substance, which is used repeatedly. The thermochemical water decomposition steps involve the following five principal reactions ... 

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