Development of solid electrolytes for water electrolysis at intermediate temperatures
- Florida Solar Energy Center, Cape Canaveral, FL (United States)
If an electrolyzer could operate at higher temperatures, several benefits would accrue. The first is that the thermodynamic electrical energy requirement to drive the reaction would be reduced. Supplying the total enthalpy of reaction at any temperature involves a combination of electrical and thermal energy inputs. Because of the positive entropy associated with water decomposition, the thermal contribution increases as temperature rises, allowing the free energy requirement to decrease. Thus the open circuit voltage, V{sub oc}, for water splitting drops as temperature rises. At room temperature, V{sub oc} for water decomposition is 1.229 V. At 400{degrees}C, voltage requirement has dropped to 1.1 V; at 1000{degrees}C, it is only 0.92 V. Since electricity is a more expensive form of energy on a btu basis, the more energy taken from the thermal surroundings the better. Moreover, this thermal energy content could be solar-derived. While the cost of solar thermal energy varies in the range of $360-900/peak kilowatt, the installed cost of photovoltaic electricity is in the range of $4,000-5,000/peak kilowatt. Thus if one is compelled to erect an array of photovoltaic panels to generate the e.m.f. necessary to split water, substituting as much area with thermal collectors as possible represents a substantial cost savings.
- Research Organization:
- National Renewable Energy Lab. (NREL), Golden, CO (United States)
- OSTI ID:
- 183302
- Report Number(s):
- NREL/CP-430-20036-Vol.2; CONF-9504160-VOL.2; ON: DE95009296; TRN: 95:008711-0014
- Resource Relation:
- Journal Volume: 18; Journal Issue: 8; Conference: 1995 DOE/NREL hydrogen program review, Coral Gables, FL (United States), 18-21 Apr 1995; Other Information: PBD: Sep 1995; Related Information: Is Part Of Proceedings of the 1995 US DOE hydrogen program review, Volume II; PB: 876 p.
- Country of Publication:
- United States
- Language:
- English
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