Preliminary Characterization of ST2G: Solar Thermionic-Thermoelectric Generator for Concentrating Systems

An innovative conversion module (CM) for concentrating solar power applications, named ST(2)G (Solar Thermionic-Thermoelectric Generator), has been developed and fabricated. The new technology is based on a solid-state converter that works at temperatures up to 1000 degrees C and exploits a double conversion stage: a thermionic stage and a thermoelectric one, connected thermally in series. Potentially, the CM could reach a combined solar energy-to-electrical efficiency larger than 30%, producing also additional thermal energy to be exploited as a co-generation. Different prototypes have been fabricated and the discussion on the technological key-points has been reported, relating them to the physical requirements necessary for an efficient conversion mechanism. The preliminary results obtained at a lab-level are here discussed, indicating low electrical power output, but also how to increase the performance by solving the identified issues.