Final Report Summary - NEXTEC (Next Generation Nano-engineered Thermoelectric Converters - from concept to industrial validation) Executive Summary:Thermoelectric (TE) materials are semiconductor materials that can convert waste heat to electrical energy or utilizing electrical energy can cause a cooling/heating effect. The key material parameters, namely Seebeck coefficient, electrical conductivity, and thermal conductivity are all interdependent material properties. Due to this, designing a high performance TE material is not a straight-forward matter of material choice, but involves smart design of material interfaces.In this project, the key strategy was to use Nanotechnology to improve performance of promising TE materials in the bulk form. Selected materials were then further processed into modules, which were tested by key industry partners. As a result of this project, new scientific knowledge and technologies were developed in the material concept as well as the module concept, which constitutes a comprehensive step forward in the field of TEs.In NEXTEC project, we first narrowed the potential industrial applications of thermoelectric modules and their implications for material development. The most attractive applications for the industry partners involved generating electricity from hot waste gases in car exhausts and industrial processes, with a maximum temperature of 600 °C. Due to the chosen temperature, skutterudites (SKT) were therefore the main focus of the material and module development in this project. The key material properties required for a stable operation of the device were identified, for example, minimum figure of merit, allowable thermal stresses, match of thermal expansion of the materials, choice of electrodes, amongst others. In addition, nanostructured bismuth telluride was also chosen for their potential in cooling applications.Material fabrication was performed with extensive support from theoretical modeling. SKT with various dopants, fillers, and other novel material concepts, such as ‘graded nanoporous’ TE materials, were investigated. During the project period, the most promising material for n- and p-type SKT was chosen and fabricated in large scales to produce prototypes of the energy generation modules. Bismuth telluride-based materials were also developed and prepared in sufficient quantities to produce cooling modules.Our SME partners developed three different prototype modules within this project. They were namely, traditional planar modules with bismuth telluride for cooling applications, planar modules with SKT for energy generation, and a novel ring module for energy generation, also with SKT. The latter was developed as a novel conceptual prototype to be introduced into the exhaust stream of cars. We have also developed application oriented test benches and simulation models for testing the performance of our energy generation modules.In addition, due to the largely unknown environmental and toxicological impact of nanomaterials, a comprehensive Life Cycle Assessment was done for SKT-based TE modules used for power generation in automobiles. The potential environmental impacts of these modules over their entire life were quantified. Hot spots were identified and the stage of synthesis of nanostructured materials appeared as the most impacting stage. LCA results showed potential benefits from energy generation during use stage and recycling at end-of-life. Besides the environmental assessment, the toxicological risk of the materials along their life cycle was evaluated. Cytotoxicity studies with the SKTs suggested that their toxicity could be similar to that of their metal components.In summary, this project, “Next Generation Nano-engineered Thermoelectric Converters – from concept to industrial validation” has largely achieved its objectives. We have investigated in-depth the physics of TE materials, and validated them with material fabrication. This has resulted in over forty journal and conference publications and the concepts were well accepted by the scientific community. In addition, we are among the pioneers in developing a prototype ring module for energy harvesting from the car exhaust gases, which is being further developed by our industrial partners. Six patents have been filed, retaining the intellectual property rights within the consortium members for future exploitation to preserve the technological edge of the European Union.Project Context and Objectives:Please See Attachment "Project context and the main objectives.pdf"Project Results:Please See Attachment "Main Results and Foreground.pdf"Potential Impact:Please See Attachment "Project Impact.pdf"List of Websites:www.eu-nextec.euwebsite is generated by KTH as the coordinator of the project. Related documents final1-nextec-final-report-v12.pdf
