### 排熱を電気に(温度差発電)

efficiency Z=(α×α)/ (ρ×κ)　（α；electromotive force , ρ; electrical resistivity and

κ;  thermal conductivity ).  To get higher Z of the material, it is important to make

electrical resistivity lower (higer electrical conductivity) and to make thermal conductivity lower as well.  However, it is difficult to obtain both reducing  thermal conductivity and increasing thermal electromotive force (TEF) since it often happens that TEF decreased by reduction of thermal conductivity.  One of the solutions is to add oxide thermal electrical semiconductor to original device.

さて、この二律背反的な特性をどのように制御し、熱電半導体の効率を上げるか、

これが達成されていないから、熱電半導体は排熱利用の、そして再生可能エネルギーの有力候補であるのに、なかなか世にデビューしないのです。冷却の方はワインクーラーボックスや光ファイバー、さらにはCCDカメラなどで利用されています。

waht is the solution of this antinomy to improve the performance of thermoelectricity ?  We have to make thermoelectric semiconductor a progressive debut by finding the solution of this problem.  We know application of "cooling" using thermoelectric semiconductor such as wine cooler, optical fibre, CCD camera, etc.,but not application of "electric power generation".  As you can see in above formula, thermal conductivity and electrical resistivity ( in other words, good electrical conductivity ) should be reduced.  However, when electrical conductiity increases, thermal conductivity enhances in generally.  The oxide may be a rescuer !