Danish startup ramps up thermoelectrics

January 19, 2017 // By Julien Happich
After years of product development in stealth mode, Danish startup TEGnology ApS is hoping to change ThermoElectric Generators (TEG) market dynamics, ramping up the production of energy harvesting modules by the tens of thousands at a competitive price.

Its first product, the FLIPTEM 36 (a 6x6 array of intertwined N & P legs) is a 21.8x18mm unit about 4mm thick, able to deliver up to 1.2mW from a 40º temperature gradient across its hot and cold sides, taken at 60 and 20ºC respectively. This device is rated for operation up to 125ºC.

Now, most competing TEG solutions today target higher temperature brackets, in the hundreds of degrees Celsius and are clearly addressed at industrial markets where they can power several Watts worth of wireless sensors mounted on hot pipes, engines or heat-dissipating process tanks.

Nevertheless, TEGnology claims it made a materials breakthrough which could potentially expand the market well beyond industrial use cases.

Thermoelectric generators based on the Seebeck effect are nothing new and there is abundant literature about the materials that qualify for energy harvesting based on temperature differentials, admits TEGnology's CEO Paul N. Egginton, but when trying to apply them in the real world, most people fail either for lack of understanding of the physics or for economic reasons, due to the materials' high cost, he says.

"Most TEG modules today are based on a scarce material, Tellurium, and this is a fundamental limitation. Go to our competition and ask them for 100,000 parts, I don't think they'll be able to produce them", the CEO told EE Times Europe in a telephone interview.

"In contrast, we manufacture our modules with readily available materials, Silicon, Zinc, Magnesium and Antimony so we can source high volumes easily" Egginton continued.

The company was founded in 2010 by TEGnology's Chairman Flemming Bjørn Hansen when he came across some interesting research results from Aarhus University (Denmark) regarding novel thermoelectric materials and their manufacture. Seminal papers published by Dr Hao Yin who later joined the company as its materials expert hint at the use of a β-phase of Zn4Sb3 directly and homogeneously synthesized through the compression of a metal powder mix under high current (spark plasma sintering). The papers report the β-Zn4Sb3 as being an excellent p-type thermoelectric semiconductor. The Silicon and Magnesium mentioned by Egginton may be in the form of a solid magnesium silicide (Mg2Si) phase obtained in a similar fashion to form the n-type legs of the TEG modules.

Hansen became a member of the Centre for Energy Materials from Aarhus University and secured exclusive rights to four initial material patents. In exchange, the Danish university received shares in the company. It took a few years to transfer the technology from university to industry and it was not until the processes were mature and stable that the company decided come out of stealth mode with a first product.