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HighTEG: New ways to generate electricity from waste heat

There is great potential in the utilisation of waste heat as an energy source, since many processes generate heat that remains unexploited to date. For example, it is possible to convert waste heat through the use of thermoelectric generators with semiconductor materials that convert heat into electrical energy. Such generators have not yet been used extensively, however, due to their time-consuming and expensive manufacturing. Evonik Creavis GmbH has developed a new manufacturing process that allows for significantly more cost-effective production in order to advance the technology and utilise the existing potential.

Thermoelectric generators offer great potential as an additional power source for waste heat conversion by converting waste heat into electrical energy without producing any emissions or noise. The generators are being tested, for example, in the automotive industry to obtain electrical power for the onboard vehicle systems from the exhaust waste heat. According to information from car manufacturers, this can save about three to four per cent of the consumed fuel. A great deal of waste heat is also produced in industrial processes and represents a potential energy resource that has hardly been exploited until now, with 300 terawatt-hours per year in Germany.

Engine for progress:

CLIMATE PROTECTION AS AN ENGINE FOR PROGRESS:

  • Expanded area of application in waste heat conversion
  • Affordable production processes
  • Low material loss
  • Robust construction
  • Easy recycling
  • Low-maintenance operation

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Photo: Evonik Creavis GmbH

This is what a thermoelectric module manufactured according to the new production process by Creavis looks like.



New manufacturing process is cheaper and more effective

Various aspects currently impede the utilisation of the generators. The traditional production process of the generators is very complex and contains a multitude of manual steps that result in high costs. Added to this is the fact that the range of application until now has typically been limited to temperatures below 200 degrees Celsius. This eliminates many industrial waste heat sources. Evonik Creavis GmbH thus developed a process intended to pave the way for the technology. The new, efficient, high-performance process for manufacturing energy converters is fully automated, thereby reducing costs. Even the size of the required generators, which depends on the amount of the processed exhaust heat, is now easier to customise and control. Additionally, there is far less material loss because no excess residue is produced due to optimised processing of the conductor material. The module is also stable and resistant as a result of the new flat surface design with fully-integrated semiconductors. A further benefit is the extended use through higher application temperatures. The generators manufactured here can be used at temperatures of up to 280 degrees.

Expanded range of application in the energy-intensive industry

A maximum of five per cent of the heat fed into the generators can be converted. However, utilising them can pay off – especially due to the extended temperature range. Possible applications arise anywhere that constant high heat flows are transferred, like in truck or marine diesel engine exhaust systems. There are also interesting potential fields of application in the energy-intensive industries like cement, glass, ceramics and metal production/processing or in foundries.

The generators with the product name ESPRYX are currently being manufactured in low volume at Evnik Creavis GmbH. The next step is to integrate systems with selected development partners. Batch production in large quantities is currently being discussed.


Photo: Evonik Creavis GmbH

“For us, the HighTEG Project, which earned us the 2016 German Sustainability Award for research, is more than just another demonstration of our innovative strength. The revolutionary design created from process innovation can significantly contribute to make the conversion of waste heat into electrical energy more affordable. The level of interest in the modules is very high. We are now just as excited as we are optimistic to receive the first positive reactions from the market in the first half of 2018.”

Prof. Dr. Stefan Buchholz, Managing Director of Evonik Creavis GmbH