Solar power towers can be used to make hydrogen on a large scale. Electrolyzers could be used to convert solar electricity produced by the power tower to hydrogen, but this process is relatively inefficient. Rather, efficiency can be much improved if solar heat is directly converted to hydrogen via a thermochemical process. In the research summarized here, the marriage of a high-temperature $(∼1000°C)$ power tower with a sulfuric acid∕hybrid thermochemical cycle was studied. The concept combines a solar power tower, a solid-particle receiver, a particle thermal energy storage system, and a hybrid-sulfuric-acid cycle. The cycle is “hybrid” because it produces hydrogen with a combination of thermal input and an electrolyzer. This solar thermochemical plant is predicted to produce hydrogen at a much lower cost than a solar-electrolyzer plant of similar size. To date, only small lab-scale tests have been conducted to demonstrate the feasibility of a few of the subsystems and a key immediate issue is demonstration of flow stability within the solid-particle receiver. The paper describes the systems analysis that led to the favorable economic conclusions and discusses the future development path.

1.
Radosevich
,
L. G.
, et al.
, 1986, “
An Assessment of Solar Central Receiver Systems for Fuels and Chemicals Applications
,” SAND86-8019, Sandia National Laboratories, October.
2.
EPRI
and
DOE
, 1997, “
Renewable Energy Technology Characterizations
,” EPRI TR 109496, December.
3.
Sargent and Lundy Consulting Group
, 2003, “
Assessment of Parabolic Trough and Power Tower Solar Technology Cost and Performance Forecasts
,” SL-5641, May.
4.
Pohl
,
P. I.
,
Brown
,
L. C.
,
Chen
,
Y.
,
Diver
,
R. B.
,
Besenbruch
,
G. E.
,
Earl
,
B. L.
,
Jones
,
S. A.
, and
Perret
,
R. F.
, 2004, “
Evaluation of Solar Thermo-Chemical Reactions for Hydrogen Production
,”
Proceedings of the 12th International Symposium Solar Power and Chemical Energy Systems
,
Oaxaca
, Mexico, Oct. http://shgr.unlv.edu/stchNew/source/login.asphttp://shgr.unlv.edu/stchNew/source/login.asp
5.
Beghi
,
G. E.
, 1986, “
A Decade of Research on Thermochemical Hydrogen at the Joint Research Centre, ISPRA
,”
Int. J. Hydrogen Energy
0360-3199,
11
(
12
), pp.
761
771
.
6.
Brown
,
L. C.
,
Besenbruch
,
G. E.
,
Lentsch
,
R. D.
,
Schultz
,
K. R.
,
Funk
,
J. F.
,
Pickard
,
P. S.
,
Marshall
,
A. C.
, and
Showalter
,
S. K.
, 2003, “
High Efficiency Generation of Hydrogen Fuels Using Nuclear Power
,” Final Technical Report for the Period August 1, 1999 through September 30, 2002, NERI Grant #, D.E.-FG03–99SF21888, GA-A24285, Dec.
7.
Westinghouse Electric Corp.
, 1982, “
Solar Thermal Hydrogen Production Process
,” DOE∕ET∕20608-1, December.
8.
Boeing Aerospace Company
, 1985, “
Small Central Receiver Brayton Cycle Study
,” Final Technical Report No. SAND84-8189, Sandia National Laboratories, Livermore, CA.
9.
Hildebrandt
,
A. F.
, and
Ross
,
K. A.
, 1985, “
Receiver Design Considerations for Solar Central Receiver Hydrogen Production
,”
Sol. Energy
0038-092X,
35
(
2
), pp.
199
206
.
10.
Hruby
,
J. M.
, 1986, “
A Technical Feasibility Study of a Solid Particle Solar Central Receiver for High Temperature Applications
,” SAND86-8211, Sandia National Laboratories, March.
11.
Babcock & Wilcox
, 1981, “
Selection and Conceptual Design of an Advanced Thermal Energy Storage Subsystem for a Commercial Scale (100 MWe) Solar Central Receiver Power Plant
,” SAND80-8190, BAW-1662, February.
12.
Kistler
,
B. L.
, 1986,
User’s Manual for DELSOL3: A Computer Code for Calculating the Optical Performance and Optimal System Design for Solar Thermal Central Receiver Plants
, SAND86-8018,
Sandia National Laboratories
,
Sandia, NM
.
13.
U.S. Department of Energy
, 2004, “
Nuclear Hydrogen R&D Plan
,” Draft—University Workshop Revision, Office of Nuclear Energy—Science and Technology, March.
14.
Evans
,
G. H.
,
Houf
,
W. G.
,
Greif
,
R.
, and
Crowe
,
C.
, 1985, “
Numerical Modeling of a Solid Particle Solar Central Receiver
,” SAND85-8249, Sandia National Laboratories, December.
15.
Houf
,
W. G.
, 2005, Personal communication with N. Siegel.
16.
National Energy Technology Lab
, “
Multiphase Flow with Interphase eXchanges (MFIX)
,” http://www.mfix.org/http://www.mfix.org/
17.
Sufrategui
,
F.
, 2004, “
Thermal Performance Evaluation of a 200 kWth “SolAir” Volumetric Solar Receiver
,” Solar Plataforma de Almeria, Spain, draft.
18.
Summers
,
W. A.
,
Gorensek
,
M. B.
, and
Buckner
,
M. B.
, 2005, “
The Hybrid Sulfur Cycle for Nuclear Hydrogen Production
,”
Proceedings of Global 2005
,
Tsukuba
, Japan, October 9–13.
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