Half-Heusler Waste Heat Conversion Reduces CO2 Emissions of Cars

Half-Heusler Waste Heat Conversion Reduces CO2 Emissions of Cars

In the energy debate about CO2 reduction, Hesse’s oldest industrial company, Isabellenhütte, is now making a promising contribution that is about ready to launch on the market. The basic idea: generate electricity from unused waste heat. The technology uses a new class of thermoelectric material to achieve this. The aim of the technology is, for example, to save up to 4% CO2 emissions when used in a car.

Together with several partner companies, Isabellenhütte has now succeeded in getting the so-called half-Heusler material, a class of thermoelectric material newly discovered by scientists 15 years ago, ready for marketability. The aim of this cooperation was and is to depict the entire added value - from development to production to the specific application. The current EU project INTEGRAL* is now focusing on the construction of three pilot productions. The goal of the established pilot lines is to produce thermoelectric material in large quantities. Already at the project halfway point in May 2018, Isabellenhütte was able to successfully demonstrate the complete production process for material batches of 10 kg with its production line.

 

Annual Production Volume of 25 Tons of Half-Heusler Material Possible

A 150 m2 production hall was built for this purpose at the company headquarters in Dillenburg, Hesse. Overall, a total of six scientists and technician are currently working on this topic at Isabellenhütte. 10 kg of thermoelectric half-Heusler material is currently being melted there per production run and processed further into functional components. This quantity is to be increased to 50 kg by the end of the project in December 2019. Theoretically, a production volume of up to 500 kg per production run is possible with the system. This corresponds to an annual production of 25 tons.

 

Thermoelectric Waste Heat Conversion is Nearly Ready for Market

Thermoelectric waste heat conversion based on half-Heuslers is almost ready for market. The technology was and is already tested and tried in the exhaust gas systems of cars and trucks under realistic everyday conditions. With 60 to 70 grams of half-Heusler material, a vehicle with a thermoelectric generator (TEG) installed achieves an efficiency of up to 5% from the waste heat. This energy is converted into electricity and fed into the onboard electrical system. The effect: The fuel consumption is reduced and the CO2 emissions are reduced per vehicle by up to 4%.

 

Relevant for Environmental Policy and Competition 

The relevance of this technology is clear: automotive manufacturers will face strict environmental requirements in the future. This is why every gram of CO2 saved matters. The half-Heusler waste heat conversion is also competitive from an economic point of view. The production process realized as part of the EU project generally makes it possible to achieve the market-demanded cost target of EUR 0.50/ watt under mass production conditions. A half-Heusler-based thermoelectric generator that, for example, generates 400 watts of electrical energy, would cost about EUR 200.

 

Useful in High-Temperature Applications

Due to their good material properties, half-Heusler materials are useful in high-temperature applications such as combustion engines. They generate exhaust gas temperatures between 400-600°C. With the aim of reducing emissions, a half-Heusler-based recuperation is therefore recommended for continuously operating high-temperature applications in the energy, metal or chemical industries. It is also attractive for the end user because it can also be used in fireplaces or heating systems. This commitment from Isabellenhütte is no coincidence. The predecessor of the half-Heusler material class, the so-called Heusler alloys, were discovered over 100 years ago by Dr. Fritz Heusler, the great-grandfather of today’s managing director of Isabellenhütte, Dr. Felix Heusler.

More information: Isabellenhütte