Development of thermoelectric devices
 
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Further Information on our Thermoelectric Research
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Thermoelectric waste heat recovery 
using environmentally benign Mg2Si
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Climate Change
Thermoelectric_E.html
Automotive
Waste Heat
Thermal-to-electric
Energy Conversion
Environmentally Benign
Semiconducting
Thermoelectric Material
Thermoelectric (TE) power generation is one of the most promising waste heat utilization methods for use in vehicles. TE power generators using Mg2Si, which is an abundant, durable, lightweight material with good TE properties at ~600 °C, are being developed for automotive use.
Climate change is a real problem, 
so we are taking real action.
The automotive industry is anxious to install thermoelectric generators (TEG) because of the strict fuel consumption regulations being introduced by the EU starting from 2020. With increasing energy prices and climate change, the interest in TE conversion for producing electric power from waste heat is strong. The main advantage of TE conversion compared to thermodynamic conversion is the absence of any moving parts. Being entirely static, and not relying on vibration to operate, the device is unaffected by wear. About seventy percent of gasoline is emitted as waste heat when we drive, so, if some percentage of this discarded heat can be reused, then fuel consumption can be improved.
 Having an on-board TEG system is one possible way of conserving fuel and supplying electricity. A successfully powerful TEG system could release auxiliary components, such as the water pump, air-conditioning compressor, power-alternator etc., from the engine, resulting in better fuel consumption. For this purpose, the automotive side typically requires a practical conversion efficiency of 7~10 %. A promising solution for the demand is to have tandem power generation structures consisting of low-temperature and mid-temperature TEGs.
Promising TE materials for automotive applications are silicides such as magnesium silicides, Mg2Si, and manganese silicides, MnSix, and Half-Heuslers such as Hf-Zr-Ni-Sn or Zr-Hf-Co-Sb-Sn. Mg2Si has emerged as one of the most promising TE materials for automotive applications, especially in Europe. This is mainly due to its light weight, the abundance of its constituent elements with a little or no risk to the material supply, and its good TE properties with sufficient durability at high operating temperatures up to ~600 °C. In order to satisfy the requirements of automotive developers wishing to install waste-heat recovery systems in vehicles, the establishment of scalable and reproducible processes is required in order to take Mg2Si TE generators into production.
Value Proposition / Achievements
Mg2Si is known to be a good TE material, but, in the past, it has been very difficult to synthesize with good crystalline quality. We successfully developed a method for synthesizing Mg2Si, providing a "breakthrough" for its introduction to TEGs. We then reduced the fabrication costs for mass production while maintaining sufficiently good TE properties and durability at 600 °C. The technology for synthesizing the material was transferred to the company. For practical use, we have recently developed a uni-leg TEG which consists of a series of n-type Mg2Si elements. The TEGs consists of easy-to-assemble TE elements housed in insulating ceramic substrates with integrated electrode plating. This provides good thermal durability at high temperatures, the potential for making a compact design, and has both low electrical& heat resistance. The power generating performance was 0.5 W/cm2 at 600/100 °C. We note that others have written reports on Mg2Si1-xSnx, which show it to have superior TE properties to Mg2Si; however, degradation due to the Sn is significant at elevated temperatures. Currently, Mg2Si TE chips are already being exported to the EU and the US.
Potential Applicability to Industrialization
We established the Waste Heat Recovery Technology Consortium of Japan (WHR) in 2009 and our laboratory has transferred related technologies in an enthusiastic manner. The members of the WHR consortium now provide Mg2Si raw materials and TE power generation chips, commercially. Our future advanced technological developments will be oriented toward the construction of TEGs and power generation systems. For future TEG systems, we expect to be focusing on the following areas; (1) pioneering brand-new TEGs with non-critical Mg2Si elements, (2) achieving sufficient power collection from TEGs and conditioning with DC-DC convertors, (3) integrating TEGs into waste-heat recovery systems, (4) the production and industrialization of TEGs to enable the automotive community to reduce CO2 emissions from vehicles. We recognize that we have to realize TE automotive waste heat recovery systems within 5 years due to EU regulations, and are sure that our current and coming fundamental mutual resources and appropriate joint schemes will contribute to satisfying the demands on TEG systems for the automotive industry.
Environmentally Benign
Semiconducting
Thermoelectric Material
Environmentally Benign
Semiconducting
Thermoelectric Material
Environmentally Benign
Semiconducting
Thermoelectric Material
Waste Heat Recovery Technology
Consortium in Japanhttp://www.whr-conso.net
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Link
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JAPANESEhttp://www.tus-iidalab.net/jpn/Thermoelectric_Top.html
Mg2Si is known to be a good TE material, but, in the past, it has been very difficult to synthesize with good crystalline quality. We successfully developed a method for synthesizing Mg2Si, providing a "breakthrough" for its introduction to TEGs. We then reduced the fabrication costs for mass production while maintaining sufficiently good TE properties and durability at 600 °C. The technology for synthesizing the material was transferred to the company. For practical use, we have recently developed a uni-leg TEG which consists of a series of n-type Mg2Si elements. The TEGs consists of easy-to-assemble TE elements housed in insulating ceramic substrates with integrated electrode plating. This provides good thermal durability at high temperatures, the potential for making a compact design, and has both low electrical& heat resistance. The power generating performance was 0.5 W/cm2 at 600/100 °C. We note that others have written reports on Mg2Si1-xSnx, which show it to have superior TE properties to Mg2Si; however, degradation due to the Sn is significant at elevated temperatures. Currently, Mg2Si TE chips are already being exported to the EU and the US.
We established the Waste Heat Recovery Technology Consortium of Japan (WHR) in 2009 and our laboratory has transferred related technologies in an enthusiastic manner. The members of the WHR consortium now provide Mg2Si raw materials and TE power generation chips, commercially. Our future advanced technological developments will be oriented toward the construction of TEGs and power generation systems. For future TEG systems, we expect to be focusing on the following areas; (1) pioneering brand-new TEGs with non-critical Mg2Si elements, (2) achieving sufficient power collection from TEGs and conditioning with DC-DC convertors, (3) integrating TEGs into waste-heat recovery systems, (4) the production and industrialization of TEGs to enable the automotive community to reduce CO2 emissions from vehicles. We recognize that we have to realize TE automotive waste heat recovery systems within 5 years due to EU regulations, and are sure that our current and coming fundamental mutual resources and appropriate joint schemes will contribute to satisfying the demands on TEG systems for the automotive industry.
 Having an on-board TEG system is one possible way of conserving fuel and supplying electricity. A successfully powerful TEG system could release auxiliary components, such as the water pump, air-conditioning compressor, power-alternator etc., from the engine, resulting in better fuel consumption. For this purpose, the automotive side typically requires a practical conversion efficiency of 7~10 %. A promising solution for the demand is to have tandem power generation structures consisting of low-temperature and mid-temperature TEGs.
Promising TE materials for automotive applications are silicides such as magnesium silicides, Mg2Si, and manganese silicides, MnSix, and Half-Heuslers such as Hf-Zr-Ni-Sn or Zr-Hf-Co-Sb-Sn. Mg2Si has emerged as one of the most promising TE materials for automotive applications, especially in Europe. This is mainly due to its light weight, the abundance of its constituent elements with a little or no risk to the material supply, and its good TE properties with sufficient durability at high operating temperatures up to ~600 °C. In order to satisfy the requirements of automotive developers wishing to install waste-heat recovery systems in vehicles, the establishment of scalable and reproducible processes is required in order to take Mg2Si TE generators into production.
The automotive industry is anxious to install thermoelectric generators (TEG) because of the strict fuel consumption regulations being introduced by the EU starting from 2020. With increasing energy prices and climate change, the interest in TE conversion for producing electric power from waste heat is strong. The main advantage of TE conversion compared to thermodynamic conversion is the absence of any moving parts. Being entirely static, and not relying on vibration to operate, the device is unaffected by wear. About seventy percent of gasoline is emitted as waste heat when we drive, so, if some percentage of this discarded heat can be reused, then fuel consumption can be improved.