Electricity made from hot air

More than 60 per cent of the energy produced in the world today ends up as wasted heat. One way to utilize the heat is to let hot air flow through a Thermoelectric Generator (TEG). Elkem could benefit from this both by producing silicon-based elements for the TEGs and by using TEG to make electricity at its plants.

A TEG-system has no moving parts, requires very little maintenance and, due to its modular design, can be fitted to almost any heat source, regardless of size. The core of a TEG is thermoelectric materials that convert a heat flow into electric current. The higher the temperature difference, the more electricity is generated. However, today TEG technology is relatively costly and in little use, since TEGs are often made of rare, expensive and even toxic materials.

The goal of Elkem’s R&D project TESil is to demonstrate that a TEG based on silicides will produce electricity at a considerably lower price than today’s TEG technology.

In TESil, Elkem hopes to develop the next generation thermoelectric materials based on low cost and harmless silicon mixed with other elements forms silicides. The silicides can handle higher temperatures than many of the TEG materials used today and can therefore convert heat to electricity more efficiently. This also opens up for many new applications, particularly in the field of waste heat recovery, but also as energy harvesters for wireless sensor networks or heat flux sensors and controls.

The next step is to integrate the silicides into a TEG that can be used for waste heat recovery purposes. Since a TEG is a more flexible way of transforming heat into electricity than the generators that are used today at large smelting plants, TEG can be a solution for electricity production at plants of all sizes, all over the world.

Norwegian research partners Sintef, University of Oslo and University of Agder will contribute with important modelling, characterisation and measurement of the silicides to achieve the highest possible efficiency and durability. The project is supported by The Research Council of Norway.