Materials for solar thermochemistry

Materials for solar thermochemistry

The solar refinery is a novel concept in which the combustion gases generated in a thermal power plant, rich in CO2 and water vapour, are reused as raw material to produce fuels through processes activated by solar power.
Conversion of abundant, but intermittent, solar energy to liquid hydrocarbon fuels can potentially provide a seamless transition for the integration of renewable fuel sources in the existing transportation infrastructure. Thermochemical processes using concentrated solar energy offer the potential to achieve high solar-to-fuel energy conversion efficiencies because solar thermal processes inherently operate at high temperatures and utilize the entire solar spectrum, providing a thermodynamically favourable path to solar fuels production. Particularly, two steps thermochemical cycles using non-stoichiometric mixed metal oxides are based in the reduction of these materials at high temperature, releasing oxygen, followed by exothermic oxidation with CO2 and H2O mixtures, with the simultaneous production of H2 and CO (syngas). The resultant product is a valuable feedstock for clean energy production (renewable liquid hydrocarbon fuels via Fischer-Tropsch processes) and chemical manufacturing applications (from polymers to acetic acid).
In this way, the aim of this research line is the development of materials for new thermochemical systems to produce syngas (CO+H2) by combined CO2/H2O splitting. The temperatures required for the process (1000-1500 °C) are reached by means of concentrating solar thermal energy systems.
The successful of these technologies requires the study of relatively inexpensive materials that efficiently extract valuable feedstock from resources that are either readily available, in the case of water, or are very relevant greenhouse gases, in the case of CO2. If both feedstock (H2O and CO2) come from the flue gas in a thermal power plant, generation of syngas as solar fuel would be considered as a part of a so-called solar refinery coupled to the thermal power plant. This would allow a drastic reduction of CO2 emissions to the atmosphere and the consequent savings in the consumption of fossil fuels at the same time.
The activities of this research line will be carried out simultaneously at the facilities of the Rey Juan Carlos University and IMDEA Energy Institute, whose research groups have been collaborating for a long time in the joint execution of research projects. The activities of the IMDEA Energy research group are focused on concentrating solar thermal energy, more specifically on the study and development of modular, dispatchable and efficient solar concentration systems.
IMDEA Energy has high scale unique R&D experimental facilities (high-flux solar simulators and solar tower) specially designed to provide high flux/high temperature conditions required for solar thermochemical research. The two high flux solar simulators are indoor facilities capable of supplying high-power density beams in well-controlled and stable operating conditions. Experimentation on solar thermochemistry at IMDEA Energy is at present performed in the framework of EU projects Sun-To-Liquids (Integrated solar-thermochemical synthesis of liquid hydrocarbon fuels, www.sun-to-liquid.eu) and SFERA III (Solar Facilities for the European Research Area – Third Phase) in addition to other national and regional research programs.