Novel two-step SnO2/SnO water-splitting cycle for solar thermochemical production of hydrogen

Abanades, Stéphane; Charvin, Patrice; Lemont, Florent; Flamant, Gilles

doi:10.1016/j.ijhydene.2008.05.042

Cited by 224 publications

(118 citation statements)

References 25 publications

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“…The target region for low-temperature thermal water splitting (yellow shaded area, T 1 , T 2 < 1;000°C) has no overlap with the practically accessible region when using a two-step process. Additionally, existing twostep thermochemical water splitting cycles that have been reported previously all operate at above 1,000°C (5,6,11,12). The conclusion that can be derived from these results is that thermochemical water splitting cycles accomplished below 1,000°C will require more than two steps, and is consistent with the previous thermodynamic analysis of Meredig and Wolverton (14).…”

Section: Resultssupporting

confidence: 87%

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Low-temperature, manganese oxide-based, thermochemical water splitting cycle

Bhawe

Davis

2012

Proc. Natl. Acad. Sci. U.S.A.

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Thermochemical cycles that split water into stoichiometric amounts of hydrogen and oxygen below 1,000°C, and do not involve toxic or corrosive intermediates, are highly desirable because they can convert heat into chemical energy in the form of hydrogen. We report a manganese-based thermochemical cycle with a highest operating temperature of 850°C that is completely recyclable and does not involve toxic or corrosive components. The thermochemical cycle utilizes redox reactions of Mn(II)/Mn(III) oxides. The shuttling of Na þ into and out of the manganese oxides in the hydrogen and oxygen evolution steps, respectively, provides the key thermodynamic driving forces and allows for the cycle to be closed at temperatures below 1,000°C. The production of hydrogen and oxygen is fully reproducible for at least five cycles.hydrogen production | Na + extraction | multistep cycle T hermochemical production of hydrogen and oxygen from water involves a series of chemical reactions that convert water into stoichiometric amounts of hydrogen and oxygen using heat as the only energy source. Thermochemical water splitting is of interest because it directly converts thermal energy into stored chemical energy (hydrogen and oxygen). Research on thermochemical water splitting cycles largely began in the 1960s and 1970s and involved nuclear reactors (1, 2) and solar collectors (3) as the energy sources. Numerous reviews of the thermochemical cycles proposed and experimentally investigated are available, e.g., (4). A large number of thermochemical cycles for splitting water has been proposed, and generally can be grouped into two broad categories: high-temperature two-step processes (5, 6) and lowtemperature multistep processes (7,8). One of us (M.E.D.) has conducted previous research on low-temperature multistep processes in the 1970s (9).Low-temperature multistep processes, typically with the a highest operating temperature below 1,000°C, allow for the use of a broader spectrum of heat sources, such as heat from nuclear power plants, and hence have attracted considerable attention. The majority of existing low-temperature processes produces intermediates that can be complex, corrosive halide mixtures. One of these processes, the sulfur-iodine cycle, has been studied extensively, and even piloted for implementation (8). This process produces strongly acidic mixtures of sulfuric and iodic acids that create significant corrosion issues, but requires only one high-temperature step at ca. 850°C. Two-step processes typically involve simpler reactions and intermediates, e.g., solid metal oxides, than the low-temperature multistep cycles. However, the temperatures required to close these types of cycles are well above 1,000°C. Because of the requirement of high-temperature heat sources, these types of cycles have been investigated for use with solar concentrators (10, 11). These cycles typically consist of one step that involves the oxidation of a metal [such as zinc (12)] or a metal oxide [such as iron (II) oxide (6, 13)] by water to produce...

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Section: Resultssupporting

confidence: 87%

“…Numerous reviews of the thermochemical cycles proposed and experimentally investigated are available, e.g., (4). A large number of thermochemical cycles for splitting water has been proposed, and generally can be grouped into two broad categories: high-temperature two-step processes (5,6) and lowtemperature multistep processes (7,8). One of us (M.E.D.)…”

mentioning

confidence: 99%

Low-temperature, manganese oxide-based, thermochemical water splitting cycle

Bhawe

Davis

2012

Proc. Natl. Acad. Sci. U.S.A.

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“…For a reduction in T H to 2280 K due to the decline in oxygen partial pressure in the inert flushing gas to 10´8 bar, both η cycle and η solar´to´f uel can be increased up to 24.5% and 29.5%, respectively. These efficiency values are comparable with other MO cycles such as the ZnO/Zn cycle (29%) [5], the SnO 2 /SnO cycle (29.8%) [33], the Fe 3 O 4 /FeO cycle (30%) [34] and the ceria cycle (20.2%) [29], which all were investigated previously employing similar operating conditions. By applying heat recuperation, η cycle and η solar´to´f uel for the Sm-WS cycle can be further enhanced [19,29,35].…”

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confidence: 85%

Solar Hydrogen Production via a Samarium Oxide-Based Thermochemical Water Splitting Cycle

et al. 2016

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Abstract:The computational thermodynamic analysis of a samarium oxide-based two-step solar thermochemical water splitting cycle is reported. The analysis is performed using HSC chemistry software and databases. The first (solar-based) step drives the thermal reduction of Sm 2 O 3 into Sm and O 2 . The second (non-solar) step corresponds to the production of H 2 via a water splitting reaction and the oxidation of Sm to Sm 2 O 3 . The equilibrium thermodynamic compositions related to the thermal reduction and water splitting steps are determined. The effect of oxygen partial pressure in the inert flushing gas on the thermal reduction temperature (T H ) is examined. An analysis based on the second law of thermodynamics is performed to determine the cycle efficiency (η cycle ) and solar-to-fuel energy conversion efficiency (η solar´to´fuel ) attainable with and without heat recuperation. The results indicate that η cycle and η solar´to´fuel both increase with decreasing T H , due to the reduction in oxygen partial pressure in the inert flushing gas. Furthermore, the recuperation of heat for the operation of the cycle significantly improves the solar reactor efficiency. For instance, in the case where T H = 2280 K, η cycle = 24.4% and η solar´to´fuel = 29.5% (without heat recuperation), while η cycle = 31.3% and η solar´to´fuel = 37.8% (with 40% heat recuperation).

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“…The search for new metal-oxide cycles is ongoing and can provide solution for the recent challenges within the field of solar thermochemical processing. In 2008 Abanades and coworkers presented the SnO 2 /SnO cycle [91]. The gap between reaction temperature and the melting point of SnO is significantly lower as for the ZnO/Zn cycle, lowering the dependency of the metal dissociation on the quenching rate.…”

Section: Challengesmentioning

confidence: 99%

Functioning devices for solar to fuel conversion

Mul¹,

Schacht²,

Swaaij³

et al. 2012

Chemical Engineering and Processing: Process Intensification

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a b s t r a c tThis paper provides a perspective on the technologies capable of converting solar energy, CO 2 and H 2 O into an easy to use fuel. The paper addresses bio-based approaches, but mainly focuses on (i) the combination of photovoltaic (PV) devices and electrocatalysis, (ii) single unit operation by photocatalytic conversion, and (iii) solar thermal conversion. Each option is described in a general manner, including a brief evaluation of the advantages and disadvantages. Also suggestions for future research endeavours are given. Based on the used literature data, for electrocatalytic and photocatalytic technologies, dramatic improvements should be made in material optimization, as well as reactor design and operation. Large efficiency gains are necessary to enable use of these technologies in practice. Solar thermal conversion is more mature, and requires specific optimization in processing, as will be discussed.

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Novel two-step SnO2/SnO water-splitting cycle for solar thermochemical production of hydrogen

Cited by 224 publications

References 25 publications

Low-temperature, manganese oxide-based, thermochemical water splitting cycle

Low-temperature, manganese oxide-based, thermochemical water splitting cycle

Solar Hydrogen Production via a Samarium Oxide-Based Thermochemical Water Splitting Cycle

Functioning devices for solar to fuel conversion

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