NEAT, acronym standing for “Nanoparticle Embedded in Alloys Thermoelectrics” is a research and development project funded in the NMP (Nanotechnology and nanosciences, knowledge-based multifunctional Materials and new Production processes and devices) programme of the Seventh Framework Programme FP7, aiming at the development and demonstration of a new class of high performance thermoelectrics nanocomposites, based on eco-friendly materials.
Thermoelectric materials, when assembled in so-called Thermoelectric Generators (TEG), are an interesting technological option to harvest a fraction of the 15TW thermal power dissipated each year by human activities. In the 27 countries of Europe, traditional power plants, transformation industries (such as glass, steel, or chemical plants) and transport activities are responsible of an enormous quantity of wasted thermal energy, estimated to be more than 520 Mtoe (Million Ton of Oil Equivalent). By transforming part of this dissipated thermal energy into usable electricity, thermoelectric devices appear as a promising opportunity for renewable energy, even if materials performances is still one of the limiting factor of their industrial development.
Until recently, the best known thermoelectric materials had figures of merit (so-called ZT, representing the thermoelectric performance of the material) values near 1. Structuring the materials at a nanometric scale level has been proposed in the 1990’s as a mean to enhance the materials performances, either by increasing the material’s power factor (product of the electrical conductivity and the squared seebeck coefficient), or by reducing its thermal conductivity. The latter has been demonstrated, with reported ZT values as high as 3 at 550K, for several types of thin film nanostructured materials. For bulk materials, however, a comparable performance has not yet been obtained.
NEAT will develop an innovative bulk alloy nanocomposite approach capable of attaining ZT>3 at high and medium temperatures by considerably decreasing the material thermal conductivity. In particular, nanoparticle inclusions and grain boundaries of the host matrix alloys will be jointly optimized in order to maximize phonon scattering at multiple length scales, without increasing electron scattering significantly.
This project aims at developing two types of nanocomposites, for the medium (300-600°C) and high (600-1000°C) temperature ranges, suitable to harvest energy in the KW range. These materials, based on eco-friendly materials will have to operate in high thermal gradient such as the ones of automotive engines or industrial systems.