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Title: Solar Hydrogen Production with a Metal Oxide-Based Thermochemical Cycle

Abstract

This research and development project is focused on the advancement of a technology that produces hydrogen at a cost that is competitive with fossil-based fuels for transportation.

Authors:
 [1]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Publication Date:
Research Org.:
Sandia National Lab. (SNL-CA), Livermore, CA (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1171559
Report Number(s):
SAND2014-17185R
537127
DOE Contract Number:
AC04-94AL85000
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

McDaniel, Anthony H. Solar Hydrogen Production with a Metal Oxide-Based Thermochemical Cycle. United States: N. p., 2014. Web. doi:10.2172/1171559.
McDaniel, Anthony H. Solar Hydrogen Production with a Metal Oxide-Based Thermochemical Cycle. United States. doi:10.2172/1171559.
McDaniel, Anthony H. Fri . "Solar Hydrogen Production with a Metal Oxide-Based Thermochemical Cycle". United States. doi:10.2172/1171559. https://www.osti.gov/servlets/purl/1171559.
@article{osti_1171559,
title = {Solar Hydrogen Production with a Metal Oxide-Based Thermochemical Cycle},
author = {McDaniel, Anthony H.},
abstractNote = {This research and development project is focused on the advancement of a technology that produces hydrogen at a cost that is competitive with fossil-based fuels for transportation.},
doi = {10.2172/1171559},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Aug 01 00:00:00 EDT 2014},
month = {Fri Aug 01 00:00:00 EDT 2014}
}

Technical Report:

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  • Abstract not provided.
  • One potential industrial application of solar energy is for the production of hydrogen (and oxygen) using a cycle of thermochemical reactions. This report provides a preliminary evaluation of the engineering feasibility of such an operation based on the cerium oxide-sodium phosphate/carbonate thermochemical cycle to produce 2 metric tons of hydrogen per day. Material and heat balances were developed, and equipment was sized. The preliminary pilot plant layout was then compared with a plant of the same capacity for producing hydrogen by the electrolysis of water. The use of water electrolysis seems superior and cheaper in all respects. 7 figures, 4more » tables.« less
  • Water decomposition cycles, of the hybrid type, involving an electrochemical cell producing hydrogen, and an oxide, and a subsequent thermochemical process loop which liberates oxygen and regenerates the lower oxide (or metal), are evaluated. A prototype cycle based on the oxides of lead: H/sub 2/O + PbO H/sub 2/ + PbO/sub 2/ (electrolysis) PbO/sub 2/ PbO + /sup 1///sub 2/O/sub 2/ (thermal decomposition) is presented. In principle, such cycles would allow the positive characteristics of conventional water electrolysis and those of thermochemical water-splitting cycles to be exploited to give higher enegy efficiencies. An equation correlating the energy efficiency to severalmore » of the process operating parameters has been developed. The calculated efficiencies of 28 percent to 46 percent for the hybrid cycles compare favorably to the 20 percent to 25 percent range for conventional water electrolysis. The hybrid processes are proported to offer comparable energy efficiencies to the thermochemical cycles. However, the hybrid processes offer increased flexbility since many reactions can be performed in electrolysis which could not ordinarily be accomplished by thermal means. Less difficult separations and fewer corrosion problems may be additional advantages offered by hybrid cycles. Certain physical and economic limitations of hybrid cycles are identified and discussed. The major problems facing the hybrid processes are the short supply and expense of the reactant material, high solubility of the anodic reactant (or product), incomplete reactions, difficult material handling, poor heat exchange characteristics, and difficult filtration due to degradation of the solid material. Although the hybrid cycles presented in this study are theoretically equal or superior to the other methods for water decomposition, their technological feasibility and economic promise are, nevertheless, not sufficient to contemplate their practical implementation.« less
  • The reaction of potassium chromate (VI) with potassium hydroxide produces hydrogen and oxygen in a thermochemical water decomposition cycle. A reaction was selected and investigated to determine the activity of potassium chromate (V), the equilibrium constant, and to assess the cycle with these data. The results of experiments to determine the reaction equilibrium constant indicate the existence of the reaction is questionable. Side reactions which may possibly explain the phemonena observed include oxidation of the nickel reactor, water absorption of potassium hydroxide, and hydrolysis of potassium oxide. A number of recommendations resulting from experimental observations are presented.