The new technology, known as the spin Seebeck effect *2, has conversion efficiency 10 times higher than the conventional method *3.
Thermoelectric conversion technology that converts energy abandoned as waste heat back to electric power could potentially save energy and reduce greenhouse gas emissions. Although conventional spin Seebeck thermoelectric devices have the advantage of low manufacturing costs and high versatility and durability, their energy conversion efficiency is inferior.
“We have improved the conversion efficiency of this spin Seebeck thermoelectric device by more than 10 times because of its newly developed material and device structure,” says Soichi Tsumura, General Manager, IoT Device Research Laboratories, NEC Corporation. “Furthermore, devices made of flexible material, such as resin, have been achieved using a manufacturing process that does not require high-temperature heat treatment.”
“The conversion efficiency of this new spin thermoelectric device has been improved by almost one million times when compared to the earliest device, and has taken an important step towards practical use as a generator element. The achievement of practical use as a heat flux sensor is also in sight,” says Tsumura.
The three parties aim to further the research and development of technologies to generate electricity from the large amount of waste heat emitted by things such as plants, data centers and vehicles.
These results were achieved as part of the “Saitoh Spin Quantum Rectification Project” led by Tohoku University Professor Eiji Saitoh. It is funded by the Exploratory Research for Advanced Technology (ERATO) program of the Japan Science and Technology Agency (JST).
*1 The Spin Seebeck effect is a thermoelectric effect discovered in 2008 by Prof. Eiji Saitoh and Associate Prof. Ken-ichi Uchida of Tohoku University (Keio University at that time). This is a phenomenon in which a temperature gradient applied in a magnetic material produces a spin current along the temperature gradient. The spin current is a flow of a magnetic property of an electron, so-called “spin”.
*2 A thermoelectric device is a device which converts thermal energy directly into electricity and vice versa.
*3 Compared with a test module that was produced based on a multi-layered SSE technology published by the Tohoku University group in 2015.
*4 The anomalous Nernst effect is a thermoelectric effect discovered about 100 years ago, which relates to the magnetic property of a conductive material.
*5 References are as follows, A. Kirihara et. al., Nature Materials 11, (2012) 686. M. Ishida, NEC Technical Journal 66(1), (2013). R. Ramos et. al., Phys. Rev. B 92, (2015) 220407(R)