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Solar Thermochemical Hydrogen Cycle Database Now Available
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By Herbert Robert Perret
University of Nevada - Las Vegas Research Foundation

Lloyd Brown and Ken Schultz
General Atomics - San Diego, CA

The University of Nevada - Las Vegas, General Atomics, Sandia National Laboratories, the University of Colorado, the National Renewable Energy Laboratory and the University of Hawaii, under DOE Hydrogen Program support are investigating thermochemical water-splitting cycles for production of hydrogen from solar energy. The study will methodically evaluate the known thermochemical water-splitting cycles for their application to solar energy. The best of these will form the basis for pilot plant design development and implementation. The project is developing an extensive database that is now available on the University of Nevada - Las Vegas Solar Hydrogen Generation Research Program web site. [1]

An extensive literature survey identified the known thermochemical cycles. These were subjected to a weighted screening technique to establish their relative merits under solar power provided by either a trough, a standard tower, an advanced tower or a dish collector. Sixteen performance or risk criteria were applied to estimate a cycle's desirability. The literature data describing over 300 distinct chemical cycles were organized into a web-based database along with the screening methodology used to reduce the number of cycles for detailed evaluation. The screening process does not determine the best process, but does eliminate cycles that have low probability of success.

Cycles that passed the initial screening were subjected to further screening, including thermodynamic analysis and preliminary chemical flowsheet development. A short list of candidates was selected based on maximum thermal efficiency of the cycle. Information from the second screening was incorporated into the database.

The web-based database and automated scoring software are available to the hydrogen community. Default settings invoke the weights used in our screening exercise, but users may investigate the effect of alternate criteria weightings.

The database and screening process are available at http://shgr.unlv.edu/ by choosing Thermochemical Cycle Automated Scoring. The database is a "Living Document" that will be updated as new data are discovered. The listing of a cycle in the SHGR database is not a certification of the cycle in any sense, as is explained in the disclaimer found on the SHGR web site. We encourage feedback from the hydrogen community on how to continue to improve the usefulness of the site.

Reference
[1] "A Database of Solar Thermochemical Hydrogen Cycles," National Hydrogen Association Meeting, 29-31 March 2005, Lloyd Brown1, Gottfried E. Besenbruch1, Yitung Chen2, Richard Diver3, Boyd Earl2, Sean Hsieh2, Kenny Kwan2, Barry W. McQuillan1, Christopher Perkins4, Phillip Pohl3, and Alan Weimer4. (1) General Atomics, (2) University of Nevada-Las Vegas, (3) Sandia National Laboratories, (4) University of Colorado

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