SBIR-STTR Award

NASA is interested in advancing green technology research for achieving sustainable and environmentally friendly energy sources for both terrestrial and space applications. It has been reported that thermo-electric power generation (TEPG) can contribute to electrical power generation scavenged from waste heat sources. Significant advantages to TE technology include: no moving parts, low-weight, modularity, covertness, high power density, low amortized cost, and long service life with no required maintenance. TEPG also has the potential of enabling large-scale electric power generation. We propose to continue are on-going research of PbTe single crystals and investigate the FAST technique, developed by Penn State Univ., to produce bulk nano-composites. We will assemble the material into TE devices and optimize the high temperature electrical contacts for minimal resistivity. We expect to standardize the processes to produce device with efficiency up to 10% (we currently have efficiency of 4.4%) by the end of Phase II. The major goal of the proposed work is to establish the feasibility that kilowatt levels of power can be produced in an environmentally clean (pollution free) manner using TEPG.

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.