Solar Hydrogen Production by a Two-Step Cycle Based on Mixed Iron Oxides

Solar Energy ◽  
2005 ◽  
Author(s):  
Martin Roeb ◽  
Christian Sattler ◽  
Ruth Klu¨ser ◽  
Nathalie Monnerie ◽  
Lamark de Oliveira ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Solar Energy ◽  
Metal Oxide ◽  
Iron Oxides ◽  
Operating Conditions ◽  
Solar Furnace ◽  
Solar Irradiation ◽  
Redox Systems ◽  
Solar Hydrogen ◽  
Solar Hydrogen Production

A very promising method for the conversion and storage of solar energy into a fuel is the dissociation of water to oxygen and hydrogen, carried out via a two-step process using metal oxide redox systems such as mixed iron oxides, coated upon multi-channeled honeycomb ceramic supports capable of absorbing solar irradiation, in a configuration similar to that encountered in automobile exhaust catalytic converters. With this configuration, the whole process can be carried out in a single solar energy converter, the process temperature can be significantly lowered compared to other thermo-chemical cycles and the re-combination of oxygen and hydrogen is prevented by fixing the oxygen in the metal oxide. For the realization of the integrated concept, research work proceeded in three parallel directions: synthesis of active redox systems, manufacture of ceramic honeycomb supports and manufacture, testing and optimization of operating conditions of a thermochemical solar receiver-reactor. The receiver-reactor has been developed and installed in the solar furnace in Cologne, Germany. It was proven that solar hydrogen production is feasible by this process demonstrating that multi cycling of the process was possible in principle.

Solar Hydrogen Production by a Two-Step Cycle Based on Mixed Iron Oxides

2005 ◽  
Vol 128 (2) ◽  
pp. 125-133 ◽  
Author(s):  
Martin Roeb ◽  
Christian Sattler ◽  
Ruth Klüser ◽  
Nathalie Monnerie ◽  
Lamark de Oliveira ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Solar Energy ◽  
Metal Oxide ◽  
Iron Oxides ◽  
Operating Conditions ◽  
Solar Furnace ◽  
Solar Irradiation ◽  
Redox Systems ◽  
Solar Hydrogen ◽  
Solar Hydrogen Production

A promising method for the conversion and storage of solar energy into hydrogen is the dissociation of water into oxygen and hydrogen, carried out via a two-step process using metal oxide redox systems such as mixed iron oxides, coated upon multi-channeled honeycomb ceramic supports capable of absorbing solar irradiation, in a configuration similar to that encountered in automobile exhaust catalytic converters. With this configuration, the whole process can be carried out in a single solar energy converter, the process temperature can be significantly lowered compared to other thermo-chemical cycles and the recombination of oxygen and hydrogen is prevented by fixing the oxygen in the metal oxide. For the realization of the integrated concept, research work proceeded in three parallel directions: synthesis of active redox systems, manufacture of ceramic honeycomb supports and manufacture, testing and optimization of operating conditions of a thermochemical solar receiver-reactor. The receiver-reactor has been developed and installed in the solar furnace in Cologne, Germany. It was proven that solar hydrogen production is feasible by this process demonstrating that multicycling of the process was possible in principle.

Kinetic Investigations of a Two-Step Thermochemical Water-Splitting Cycle Using Mixed Iron Oxides Fixed on Ceramic Substrates

2008 ◽  
Author(s):  
Martina Neises ◽  
Martin Roeb ◽  
Martin Schmu¨cker ◽  
Christian Sattler ◽  
Robert Pitz-Paal
Keyword(s):  
Activation Energy ◽  
Hydrogen Production ◽  
Metal Oxide ◽  
Water Splitting ◽  
Iron Oxides ◽  
Reaction Rate ◽  
Solar Furnace ◽  
Solar Irradiation ◽  
Test Rig ◽  
Kinetics Of

A two-step thermochemical cycle for solar hydrogen production using mixed iron oxides as the metal oxide redox system has been investigated. A reactor concept has been developed in which the metal oxide is fixed on multi-channelled honeycomb ceramic supports capable of adsorbing solar irradiation. In the solar furnace of DLR in Cologne coated honeycomb structures were tested in a solar receiver-reactor with respect to their water splitting capability and their long term stability. The concept of this new reactor design has proven feasible and constant hydrogen production during repeated cycles has been shown. For a further optimization of the process and in order to gain reliable performance predictions more information about the process especially concerning the kinetics of the oxidation and the reduction step are essential. To examine the kinetics of the water splitting and the regeneration step a test rig has been built up on a laboratory scale. In this test rig small coated honeycombs are heated by an electric furnace. The honeycomb is placed inside a tube reactor and can be flushed with water vapour or with an inert gas. A homogeneous temperature within the sample is reached and testing conditions are reproducible. Through analysis of the product gas the hydrogen production is monitored and a reaction rate describing the hydrogen production rate per gram ferrite can be formulated. Using this test set-up, SiC honeycombs coated with a zinc-ferrite have been tested. The influences of the water splitting temperature and the water concentration on the kinetics of the water splitting step have been investigated. A mathematical approach for the reaction rate was formulated and the activation energy was calculated from the experimental data. An activation energy of 110 kJ/mole was found.

Dimensioning and Simulation of a Pilot Plant for Solar Hydrogen Production

2010 ◽  
Author(s):  
Yasmina Ziari Kerboua ◽  
Lofti Ziani ◽  
Bouziane Mahmah ◽  
Ahmed Benzaoui
Keyword(s):  
Renewable Energy ◽  
Hydrogen Production ◽  
Solar Energy ◽  
Pilot Plant ◽  
Photovoltaic System ◽  
Water Dissociation ◽  
Production Potential ◽  
Solar Hydrogen ◽  
System A ◽  
Solar Hydrogen Production

Hydrogen is regarded as the potential bearer of energy of the future. Solar hydrogen is the hydrogen produced using renewable energy, particularly solar energy [15,8]. The availability of water and hours of sunshine make Algeria a place of choice for solar hydrogen production. In this work, solar hydrogen production by electrolysis of water is considered. The required energy for water dissociation is supplied by a photovoltaic system. A design and operation study of a photovoltaic system has been done for three different regions in Algeria. The production potential is highly significant particularly in the south parts of this country.

Preparation of Mixed Iron Oxides for Solar Hydrogen Production by Means of the Pechini Technique

2007 ◽  
Author(s):  
Mari´a J. Marcos ◽  
Teresa Herna´ndez ◽  
Miguel Sa´nchez ◽  
Alberto J. Quejido ◽  
Manuel Romero
Keyword(s):  
Hydrogen Production ◽  
Iron Oxides ◽  
Mixed Oxides ◽  
Manganese Content ◽  
Test Facility ◽  
Activation Temperature ◽  
Solar Hydrogen ◽  
Operation Conditions ◽  
Mixed Ferrite ◽  
Solar Hydrogen Production

A process of synthesis of mixed iron oxides for their application to solar hydrogen production is reported. To analyze the suitability of the selected technique, different compositions in the compound MnxNi1−xFe2O4−5 were prepared by varying the Ni/Mn ratio between 0 and 3. The main objective was to identify the optimal amount of dopants for hydrogen production in such a magnetite. The powders were obtained from a solution of Ni, Mn and Fe nitrates by a polymeric method based on the Pechini process and were characterized by XRD and SEM. The characterization results indicated that the magnetite is fully developed at 1200°C by a multi-step solid state reaction between the mixed oxides produced after the resin heating (α- Fe2O3 and nickel-iron spinel). The particles have a polygonal morphology and are softly agglomerate. Their grain size vary with de manganese content and is about 1 micron for 0.25Mn in the mixed ferrite composition and 10 micron in the mixed ferrite without nickel. The activation endothermic step eventually resulting in an oxygen-deficient ferrite was carried out within a thermogravimetric balance. The TGA/DTA mixed magnetite analysis carried out with nitrogen as inert carrier gas showed a weight loss that can be attributed to the partial reduction of the magnetite. The weight losses and the activation temperature increases when the Ni/Mn ratio decreases, being 0.5% at 700°C and 2.57% at 900°C for Ni/Mn ratio 3 and 0 respectively. A series of experimental tests will follow at laboratory test facility with indirect and direct illumination, in order to select the most adequate operation conditions and to quantify the maximum cycle efficiency for a solarized process.

Metal oxide photoanodes for solar hydrogen production

2008 ◽  
Vol 18 (20) ◽  
pp. 2298 ◽  
Author(s):  
Bruce D. Alexander ◽  
Pawel J. Kulesza ◽  
Iwona Rutkowska ◽  
Renata Solarska ◽  
Jan Augustynski
Keyword(s):  
Hydrogen Production ◽  
Metal Oxide ◽  
Solar Hydrogen ◽  
Solar Hydrogen Production
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