Towards chemical equilibrium in thermochemical water splitting. Part 2: Re-oxidation DOI Creative Commons
Alberto de la Calle, Ivan Ermanoski, James E. Miller

et al.

International Journal of Hydrogen Energy, Journal Year: 2024, Volume and Issue: 72, P. 1159 - 1168

Published: June 1, 2024

Chemical equilibrium represents the highest efficiency achievable by a thermochemical cycle under specific operational conditions. This study delves into two-step water splitting cycles, which dissociate hydrogen (H2) and oxygen (O2) via sequential thermal reduction re-oxidation processes. Building on analysis presented in Part 1, this paper zeroes reaction within optimal reactor framework – counter-current reactor. It elucidates pathway, delineating progression of chemical at each incremental stage re-oxidation. Using ceria (CeO2) as model redox-active metal oxide, investigation analyzes influence parameters reaction. Findings reveal theoretical feasibility maintaining near constant temperature (±2.5 °C) during re-oxidation, achieving total extent 0.038 conversion yield 32%. While adiabatic operation is also achievable, practicality constrained maximum 6.5·10−3. The explores economic implications splitting, particularly focusing steam-to-hydrogen output ratio. highlights severe hurdles associated with yields below approximately 1%. Furthermore, reveals that addition inert gas to step offers no significant advantages. Concluding analysis, comparative assessment exposes negligible differences outcomes when substituting carbon dioxide (CO2) for (H2O) oxidant low-temperature scenarios (800 °C). comprehensive not only advances understanding dynamics but informs practical considerations crucial advancement technology.

Language: Английский

An updated review and perspective on efficient hydrogen generation via solar thermal water splitting DOI Creative Commons
Justin T. Tran, Kent J. Warren, Steven A. Wilson

et al.

Wiley Interdisciplinary Reviews Energy and Environment, Journal Year: 2024, Volume and Issue: 13(4)

Published: July 1, 2024

Abstract Solar thermal water splitting (STWS) produces renewable (or green) hydrogen from using concentrated sunlight. Because STWS utilizes energy the entire solar spectrum to drive reduction–oxidation (redox) reactions that split water, it can achieve high theoretical solar‐to‐hydrogen efficiencies. In a two‐step process, metal oxide serves as redox mediator is first heated with sunlight temperatures ( T >1000°C) reduce and evolve oxygen. second step, reduced material exposed steam reoxidize its original oxidation state produce hydrogen. Various aspects of this process are comprehensively reviewed in work, including reduction chemistries active materials considered date, reactors developed facilitate reactions, effects operating conditions—including recent innovation elevated oxidant pressure—on efficiency. To conclude review, perspective on future optimization provided. This article categorized under: Sustainable Energy > Emerging Technologies Hydrogen Fuel Cells New Fuels

Language: Английский

Citations

7
Towards chemical equilibrium in thermochemical water splitting. Part 2: Re-oxidation DOI Creative Commons
Alberto de la Calle, Ivan Ermanoski, James E. Miller

et al.

International Journal of Hydrogen Energy, Journal Year: 2024, Volume and Issue: 72, P. 1159 - 1168

Published: June 1, 2024

Chemical equilibrium represents the highest efficiency achievable by a thermochemical cycle under specific operational conditions. This study delves into two-step water splitting cycles, which dissociate hydrogen (H2) and oxygen (O2) via sequential thermal reduction re-oxidation processes. Building on analysis presented in Part 1, this paper zeroes reaction within optimal reactor framework – counter-current reactor. It elucidates pathway, delineating progression of chemical at each incremental stage re-oxidation. Using ceria (CeO2) as model redox-active metal oxide, investigation analyzes influence parameters reaction. Findings reveal theoretical feasibility maintaining near constant temperature (±2.5 °C) during re-oxidation, achieving total extent 0.038 conversion yield 32%. While adiabatic operation is also achievable, practicality constrained maximum 6.5·10−3. The explores economic implications splitting, particularly focusing steam-to-hydrogen output ratio. highlights severe hurdles associated with yields below approximately 1%. Furthermore, reveals that addition inert gas to step offers no significant advantages. Concluding analysis, comparative assessment exposes negligible differences outcomes when substituting carbon dioxide (CO2) for (H2O) oxidant low-temperature scenarios (800 °C). comprehensive not only advances understanding dynamics but informs practical considerations crucial advancement technology.

Language: Английский

Citations

2