Simulative Approach to Waste Heat Recovery in Solar Thermochemical Cycles by Thermoelectric Generators

Kurzfassung

Combining carbon monoxide with hydrogen (synthesis gas or syngas) results in the generation of methanol, which serves as the fundamental building block for various fuel synthesis processes. An innovative technique for the production of syngas is the combination of thermal and chemical energy obtained through the REDOX reaction of metal oxides. The process is energy-intensive, requiring high reduction temperatures of 1500 to 2000 °C emitting a significant amount of waste heat. One approach of increasing the efficiency in thermochemical cycles is to feed the released thermal energy into process heat or convert it into other useful forms of energy (e.g. electrical energy). Conversion of thermal energy into electricity is feasible using thermoelectric generators (TEG). Prototype thermoelectric modules for application temperatures up to 550 °C have been developed and characterised under various boundary temperatures. Based on the experimental material properties, a simulative analysis of different integration schemes of TEG into heat flow paths in the thermochemical cycle is presented together with modelling of the expected power output and comparison to alternative energy integration schemes (e.g. Rankine cycle). An estimation of the techno-economical feasibility under certain boundary conditions is provided.