CO2 and H2O conversion to solar fuels via two-step solar thermochemical looping using iron oxide redox pair

2011 ◽  
Vol 175 ◽  
pp. 368-375 ◽  
Author(s):  
Stéphane Abanades ◽  
Heidi Isabel Villafan-Vidales
Keyword(s):  
Iron Oxide ◽  
Solar Fuels ◽  
Redox Pair ◽  
Solar Thermochemical

Solar Thermochemical Water-Splitting Ferrite-Cycle Heat Engines

Solar Energy ◽  
2006 ◽  
Author(s):  
Richard B. Diver ◽  
James E. Miller ◽  
Mark D. Allendorf ◽  
Nathan P. Siegel ◽  
Roy E. Hogan
Keyword(s):  
Iron Oxide ◽  
High Efficiency ◽  
Heat Engine ◽  
High Concentration ◽  
Thermochemical Cycles ◽  
Design Concepts ◽  
Heat Engines ◽  
Close Proximity ◽  
Solar Thermochemical ◽  
Development Approach

Thermochemical cycles are a type of heat engine that utilize high-temperature heat to produce chemical work. Like their mechanical work-producing counterparts, their efficiency depends on operating temperature and on the irreversibilities of their internal processes. With this in mind, we have invented innovative design concepts for two-step solar-driven thermochemical heat engines based on iron oxide and iron oxide mixed with other metal oxides (ferrites). These concepts utilize two sets of moving beds of ferrite reactant material in close proximity and moving in opposite directions to overcome a major impediment to achieving high efficiency – thermal recuperation between solids in efficient counter-current arrangements. They also provide inherent separation of the product hydrogen and oxygen and are an excellent match with high-concentration solar flux. However, they also impose unique requirements on the ferrite reactants and materials of construction as well as an understanding of the chemical and cycle thermodynamics. In this paper, the Counter-Rotating-Ring Receiver/Reactor/Recuperator (CR5) solar thermochemical heat engine concept is introduced and its basic operating principals are described. Preliminary thermal efficiency estimates are presented and discussed. Our results and development approach are also outlined.

scholarly journals Solar Thermochemical Water-Splitting Ferrite-Cycle Heat Engines

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Richard B. Diver ◽  
James E. Miller ◽  
Mark D. Allendorf ◽  
Nathan P. Siegel ◽  
Roy E. Hogan
Keyword(s):  
Iron Oxide ◽  
High Efficiency ◽  
Heat Engine ◽  
High Concentration ◽  
Thermochemical Cycles ◽  
Design Concepts ◽  
Heat Engines ◽  
Close Proximity ◽  
Solar Thermochemical ◽  
Development Approach

Thermochemical cycles are a type of heat engine that utilize high-temperature heat to produce chemical work. Like their mechanical work producing counterparts, their efficiency depends on the operating temperature and on the irreversibility of their internal processes. With this in mind, we have invented innovative design concepts for two-step solar-driven thermochemical heat engines based on iron oxide and iron oxide mixed with other metal oxide (ferrites) working materials. The design concepts utilize two sets of moving beds of ferrite reactant materials in close proximity and moving in opposite directions to overcome a major impediment to achieving high efficiency—thermal recuperation between solids in efficient countercurrent arrangements. They also provide an inherent separation of the product hydrogen and oxygen and are an excellent match with a high-concentration solar flux. However, they also impose unique requirements on the ferrite reactants and materials of construction as well as an understanding of the chemical and cycle thermodynamics. In this paper, the counter-rotating-ring receiver∕reactor∕recuperator solar thermochemical heat engine concept is introduced, and its basic operating principles are described. Preliminary thermal efficiency estimates are presented and discussed. Our results and development approach are also outlined.

Design of a Novel High Temperature Gravity-Fed Solar Thermochemical Reactor for Solar-Fuels Production: Case Study - ZnO Powder

2011 ◽  
Author(s):  
Erik Koepf ◽  
Suresh G. Advani ◽  
Ajay K. Prasad
Keyword(s):  
Large Scale ◽  
High Efficiency ◽  
Combustion Engine ◽  
The United States ◽  
Solar Fuels ◽  
Thermochemical Cycle ◽  
Carbon Neutrality ◽  
Gravity Driven ◽  
Solar Thermochemical ◽  
Zno Powder

Solar fuels are emerging as a viable pathway towards closing the gap between fuel production and consumption in the United States. If these fuels can be produced on large scale and achieve carbon-neutrality, a truly sustainable energy solution may be realized. Hydrogen is among the list of attractive solar fuels. Whether used in a PEM fuel cell or combustion engine, hydrogen as a fuel produced from sunlight and water represents an elegant energy harvesting cycle, with zero-emissions, high efficiency, and exceptional power-density. A novel solar-thermochemical reactor has been designed and constructed for the reduction of ZnO at temperatures close to 2000K as the first step in a closed two-step thermochemical cycle to produce hydrogen from water as a solar fuel. Abbreviated as GRAFSTRR (Gravity-Fed Solar-Thermochemical Receiver/Reactor), the reactor is closed to the atmosphere, and features an inverted conical-shaped reaction surface along which ZnO powder descends continuously as a falling sheet and undergoes a thermochemical reaction upon exposure to highly concentrated sunlight. The reactant feed is vibration-induced, metered, and gravity-driven. Beam-down, highly concentrated sunlight enters the reaction cavity through a water-cooled aperture, and Zn product gas is siphoned into a centrally-located exit stream via a stabilized vortex flow of inert gas originating from above the aperture plane. Unreacted or partially reacted solids exit annularly around the product stream. In this paper the GRAFSTRR concept is presented. Select design choices and investigations are summarized.

Iron Oxide Nanostructures for the Reduction of Bicarbonate to Solar Fuels

2018 ◽  
Vol 61 (7-8) ◽  
pp. 601-609 ◽  
Author(s):  
Hanqing Pan ◽  
Kristian R. Martindale ◽  
Michael D. Heagy
Keyword(s):  
Iron Oxide ◽  
Solar Fuels ◽  
Oxide Nanostructures ◽  
Iron Oxide Nanostructures

Production mechanism analysis of H 2 and CO via solar thermochemical cycles based on iron oxide (Fe 3 O 4 ) at high temperature

Solar Energy ◽  
2017 ◽  
Vol 148 ◽  
pp. 117-127 ◽  
Author(s):  
Bachirou Guene Lougou ◽  
Jiarong Hong ◽  
Yong Shuai ◽  
Xing Huang ◽  
Yuan Yuan ◽  
...  
Keyword(s):  
High Temperature ◽  
Iron Oxide ◽  
Mechanism Analysis ◽  
Production Mechanism ◽  
Thermochemical Cycles ◽  
Solar Thermochemical

scholarly journals Utilization of Crystalline and Amorphous Silica as a Sintering Inhibitor in Iron/Iron Oxide Thermochemical Water Splitting Cycle

2021 ◽  
Vol 3 ◽  
Author(s):  
Fotouh Al-Ragom
Keyword(s):  
Iron Oxide ◽  
Solid State ◽  
Hydrogen Production ◽  
Amorphous Silica ◽  
Experimental Investigations ◽  
Hydrogen Yield ◽  
Redox Cycles ◽  
Redox Pair ◽  
Iron Iron ◽  
State Mixing

Hydrogen as a chemical fuel and energy carrier can provide the path to solar energy storage to overcome the intermittency issues. Hydrogen can be produced by various methods; among them is the thermochemical water splitting of metal/metal oxide reduction oxidization (redox) reactions. Many redox cycles were identified, including the non-volatile redox pair, such as the iron/iron oxide. This redox pair has the capability to produce Hydrogen with rapid reaction rates especially when it is used in powder form due to the high specific reactive surface area. Yet, this pair suffers from sintering at temperatures exceeding 500°C. Sintering adversely affects the Hydrogen production process and inhibits the recycling of the powder. To overcome sintering, experimental investigations using elemental iron and silica were conducted as detailed in this paper. The oxidation of elemental iron (Fe) powder by steam to produce Hydrogen was carried out using a fluidized bed reactor. The investigations aimed at developing a practical sintering inhibition technique that can allow repeated redox cycles, stabilize the powder reactivity, and maintain Hydrogen production. The experimental investigations involved varying the fluidized bed temperature between 630–968°C. The steam mass flow rate was set to 2 g/min. To inhibit sintering, solid-state mixing of crystalline, or amorphous silica with porous iron powder was used at various iron/silica volume fractions. The investigations showed that mixing iron with silica hinders the sintering but reduces the Hydrogen yield. Mixing iron with crystalline silica with 0.5, 0.67, and 0.75 apparent volume fraction reduces the Hydrogen yield compared to pure iron by 20, 30, and 45%, respectively. Mixing iron with amorphous silica reduces the Hydrogen yield by 35 and 45%, as compared to pure iron, for iron 0–250 and 125–355 µm particle size distribution, respectively. The Hydrogen production rate for iron/amorphous silica mixtures surpassed that of the iron/crystalline silica. Mixing iron with amorphous silica prevented sintering at elevated bed temperatures in the range of 850°C, and only clumping occurred. The clumped samples restored their original powder condition with minimum agitation. Thus, solid-state mixing of amorphous silica with iron powder can be a promising technique to retard iron/iron oxide particles sintering.

scholarly journals Compositional and operational impacts on the thermochemical reduction of CO2 to CO by iron oxide/yttria-stabilized zirconia

RSC Advances ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 1493-1502
Author(s):  
Eric N. Coker ◽  
Andrea Ambrosini ◽  
James E. Miller
Keyword(s):  
Iron Oxide ◽  
Redox Chemistry ◽  
Yttria Stabilized Zirconia ◽  
Stabilized Zirconia ◽  
Synthetic Fuels ◽  
Active Materials ◽  
Thermochemical Reduction ◽  
Solar Thermochemical ◽  
Reduction Of Co2 ◽  
Operational Impacts

The versatile redox chemistry of ferrites makes them useful as active materials for the solar-thermochemical production of synthetic fuels. Optimization of the distribution of iron in a YSZ matrix allows the performance of ferrites to be enhanced.

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