Development of thermoelectric generating stacked modules aiming for 15% of conversion efficiency

Under NEDO project "The development for advanced thermoelectric conversion system", Komatsu Ltd. is involved in R&D for suicide, Bi-Te and their cascading modules. Aiming to 15% of conversion efficiency /spl eta/ under the hot side T/sub h/=580/spl deg/C and the cold side T/sub c/=30/spl deg/C until March, 2007, 12% as midterm target was already well attained. In the next 2 years, module designing as well as materials tuning are surely the major topics in terms of superior durability. Bi-Te module, which is established as Peltier cooler, was adjusted to be suitable for generation purpose. So far, better than 7.8% of conversion efficiency with T/sub h/=280/spl deg/C and T/sub c/=30/spl deg/C was obtained and reproducibility was also well confirmed. Komatsu started investigation for suicide materials as well as module fabrication together with this NEDO project. The performance of suicide module using n-type Mg-Si and p-type MnSi are being steadily improved due to not only the elevation of Z-values of the materials but also maturity of module fabrication technique. Then, better than 8% of efficiency has been maintained at T/sub h/=550/spl deg/C and T/sub c/=30/spl deg/C. Besides each single module, the cascading one was successfully stacked and the performance was achieved almost as expected. /spl eta/=12.1% with T/sub h/=550/spl deg/C and T/sub c/=30/spl deg/C was actually accomplished up to now.