Analysis of Thermoelectric Generators Replacing Low Temperature Heat Exchangers in the Biomass CHP Plant Gu¨ssing

A thermoelectric generator (TEG) produces electric power directly out of a heat flux across a certain temperature difference. This thermoelectric effect is based on interlinking effects of thermodynamic forces and fluxes (Seebeck and Peltier effect). Within the present work, a prototype unit using Bi₂Te₃ semiconductor elements is installed at the biomass combined heat and power (CHP) plant in Gu¨ssing, Austria. Different operation points are examined according to a specific test program in order to find operating figures and describe the technical and economical potential of the TEG. A model of the TEG is implemented in the simulation software IPSEpro and verified with results from the experiments. Based on the model, the test plant is extrapolated to the size of possible demonstration plants for which electric output and energetic efficiency are calculated. For the entire CHP plant, the costs for retrofitting standard heat exchangers to TEGs are calculated and compared to the expected revenues from feeding the additional electricity into the grid. It can be concluded that the TEG gives way for new concepts and ideas but the expenses, especially with respect to the high material costs of the semiconductor, do not support a technically efficient and economically lucrative application of the TEG combined with decentralized heat and power production at present time.