Alternative Green Technology for Power Generation Using Waste-Heat Energy And Advanced Thermoelectric Materials

NASA is interested in advancing green technology research for achieving sustainable and environmentally friendly energy sources. Thermo-electric power generation (TEPG) has exceptionally rich potential to fulfill this need. A TEPG module requires (1) material that can provide high figure of merit while still providing efficient heat control; (2) low resistance ohmic contacts that operate at high temperature; and (3) efficient heat sink material to provide optimal temperature difference between hot and cold junctions. In Phase I, we addressed all of these issues. We successfully produced device quality n-type and p-type, single crystalline and bulk nano-composite PbTe material suitable for TEPG device fabrication. We also developed a novel electrical contact technology having low electrical resistance and capability to withstand significantly elevated temperatures (>800 degree C). And we developed a light weight, highly thermal conductive (50 to 60 % better than copper) heat sink material with tailored low coefficient of thermal expansion (CTE). These improvements allowed us to develop the design and technique for fabrication of large scale TEPG on a manufacturing level. In Phase II we will expand upon these developments and implement them. We will fabricate TEPG devices using the nano-composite materials. These devices will utilize the ohmic contacts and the heat sink technology that we developed. We will also utilize another approach that we developed in which two materials (PbTe and (Bi-Sb)2(Se-Te)3 based alloys) are segmented into a two-part material that has high efficiency over the entire temperature range from 200-500 degreeC, PbTe being at the hot end and the (Bi-Sb)2(Se-Te)3 based material at the cold end. Our ultimate goal will be to build a TEPG module using such segmented devices to demonstrate the generation of 1kWatt of power. We will develop the technology of fabricating these modules at a large scale manufacturing level, at low cost.