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Status
Electronic Resource
Call number
Publication
DOE JPL 1060 71; Report; May 1984.
Language
Library's review
ABSTRACT:
The single most important factor in determining the cost of fuel produced by a commercial-scale solar photochemical plant is the overall efficiency which is limited primarily by the relatively low efficiency of the solar photochemical process. The results of that study are summarized in
Because of the pivotal role of photochemical efficiency in determining the economic viability of fuel production, the current status and potential of fuel-producing solar photochemical processes are discussed in this report.
Research has focused almost exclusively on splitting water to produce dihydrogen and is at a relatively early stage of development. Current emphasis is primarily directed toward understanding the basic chemistry underlying such solar quantum conversion processes.
Theoretical analyses by various investigators predict a limiting thermodynamic efficiency of 31% for devices with a single photosystem operating with unfocused sunlight at 300 K. When non-idealities are included, it appears unlikely that actual devices will have efficiencies greater than 12 to 15%. Observed efficiencies are well below theoretical limits. Cyclic homogeneous photochemical processes for splitting water have efficiencies considerably less than 1%. Efficiency can be significantly increased by addition of a sacrificial reagent; however, such systems are no longer cyclic and it is doubtful that they would be economical on a commercial scale. The observed efficiencies for photoelectrochemical processes are also low but such systems appear more promising than homogeneous photochemical systems.
Operating and systems options, including operation at elevated temperature and hybrid and coupled quantum-thermal conversion processes, are also considered.
The single most important factor in determining the cost of fuel produced by a commercial-scale solar photochemical plant is the overall efficiency which is limited primarily by the relatively low efficiency of the solar photochemical process. The results of that study are summarized in
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Section III of this report. A more detailed account is given in "Solar Photochemical Process Engineering for Production of Fuels and Chemicals."Because of the pivotal role of photochemical efficiency in determining the economic viability of fuel production, the current status and potential of fuel-producing solar photochemical processes are discussed in this report.
Research has focused almost exclusively on splitting water to produce dihydrogen and is at a relatively early stage of development. Current emphasis is primarily directed toward understanding the basic chemistry underlying such solar quantum conversion processes.
Theoretical analyses by various investigators predict a limiting thermodynamic efficiency of 31% for devices with a single photosystem operating with unfocused sunlight at 300 K. When non-idealities are included, it appears unlikely that actual devices will have efficiencies greater than 12 to 15%. Observed efficiencies are well below theoretical limits. Cyclic homogeneous photochemical processes for splitting water have efficiencies considerably less than 1%. Efficiency can be significantly increased by addition of a sacrificial reagent; however, such systems are no longer cyclic and it is doubtful that they would be economical on a commercial scale. The observed efficiencies for photoelectrochemical processes are also low but such systems appear more promising than homogeneous photochemical systems.
Operating and systems options, including operation at elevated temperature and hybrid and coupled quantum-thermal conversion processes, are also considered.
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