As an alternative to conventional fossil fuels, the research community has been developing concepts for systems that can use solar energy to generate high-temperature steam for transportation fuel production. One promising approach involves using a solar thermal system to dissociate the water molecules (H2O) in steam and carbon dioxide (CO2) gas in the presence of certain catalysts, creating a stream of hydrogen (H2) gas and carbon monoxide (CO), respectively. The resulting mixture of H2 and CO, known as “syngas,” can be used as a fuel source or as a feedstock for a wide range of chemicals and fuels. This technique holds great promise, but requires robust, high-temperature structural reactor materials, such as ceramics, to contain the reactions. Few materials are well-suited to repeated exposure to high-temperature steam (1,500 °C) for long periods of time, without suffering significant degradation. Existing high-temperature coatings are limited to 1,400 ºC under combustion conditions, preventing their use in solar thermal reactors. However, certain ceramic materials appear promising due to their high-strength and chemical inertness.
Project Innovation + Advantages:
Saint-Gobain Ceramics & Plastics is conducting early-stage research to extend operating temperatures of industrial ceramics in steam-containing atmospheres up to 1,500 °C. Materials that are able to adequately withstand these punishing conditions are needed to create durable solar fuel reactors. The most attractive material based on high-temperature strength and thermal shock resistance is sintered (the process of compacting solid material without melting it) silicon carbide (SiC). However, the highly reactive H2O/H2/CO/CO2 atmosphere within a solar reactor causes most industrial ceramics, including SiC, to degrade at temperatures above 1,200 °C. At those temperatures volatile reaction products are formed, which continually eat away at the integrity of the reactor walls. The Saint-Gobain team is conducting research along three lines of inquiry: 1) Creating high-temperature coatings for the SiC material; 2) Creating “self-healing” SiC surfaces which are created via an oxidation reaction on an ongoing basis as the surface layer is damaged; and 3) Testing alternative ceramic materials which could be more robust. The results of the three lines of inquiry will be evaluated based on stability modeling and thermal cycling testing (i.e. repeatedly heating and cooling the materials) under simulated conditions. As an ARPA-E IDEAS project, this research is at a very early stage. If successful, the technology could potentially result in significant energy and cost savings to the U.S. economy by allowing liquid transportation fuel to be produced from water and carbon dioxide from the air via solar energy instead of conventional sources. In addition SiC materials with enhanced oxidation resistance could be applied to vessels and components across many industrial, thermal, chemical, and petrochemical processes.