Description: Solid-state thermoelectric (TE) devices provide many advantages in refrigeration (TE coolers) and power generation (TE generators). These highly reliable devices have no moving parts, operate over a large range of temperatures, and do not emit toxic or environmentally-unfriendly gases. These devices can be easily integrated into thermal energy conversion systems that meet NASA's needs for innovative space power generation on orbiting platforms, extraterrestrial surfaces, and space transportation vehicles. To date, the adoption of TE generator (TEG) devices in energy scavenging/power recovery applications has been hampered by three primary challenges: - Lack of thermoelectric material compositions with large figures of merit, ZT, that function over a range of operating temperatures - Lack of high throughput production methods that enable large-area, conformable TEG devices - High cost-per-unit area for tiling rigid plate TE devices Production of large-area sheets of high-ZT TEG devices that conform to space vehicle and other relevant thermal gradient surfaces acting to scavenge waste heat need specific processes (e.g. roll-to-roll). Nanohmics Inc. proposes to develop thermoelectric devices based on sintering of high-ZT thermoelectric powders. This TEG fabrication method will enable large-area, conformable devices with 1) high thermal-to-electric conversion efficiency, 2) high areal power conversion (W/cm2), 3) large total power recovery (W), 4) high specific power (W/kg), 5) low fabrication cost ($/W), and 6) durability and long operational life.

Benefits: Space power engineers can use these devices to produce custom fit power generation systems directly on surfaces with high temperature differences such as the hull of a space vehicle, satellite thermal busses, and extraterrestrial shelter materials. These large-area, integrated thermoelectric sheets will provide a means to maximize the extraction of otherwise wasted heat for both NASA and commercial applications such as automotive/aerospace exhaust systems, effluent piping, and petrochemical refining equipment. The proposed device embodiment is the only significant concept amendable to attachment to the contours and surfaces of space vehicles and as such will have a significant impact on generate power during space missions.

Unrecovered waste heat from energy-consuming industrial processes is estimated by the DoE at 5-13 quads/yr (1 quad = 1015 BTU). Assuming a conservative 9 quads, 6% efficiency for TE devices constructed with our approach, 50% losses due to parasitic heat transfer losses and integration, and penetrating 10% of the waste heat market, we estimate an economically viable TE device could enable recovery of ~20 trillion BTU of waste heat/year. Additionally, the incorporation of TE devices in automobiles can improve the efficiency of their power system by up to 5%. This level of waste heat energy recovery would lower the average consumer gas consumption ~15-20 gallons per year on a 750-gallon consumption/year basis with a cost savings on the order of $70-$100/year. A low-cost manufacturing solution at the ~$100 price point would pay back in the first year, passing the savings onto the lifetime of the device, which based on non-moving parts, should be relatively long. Technologies such as our proposed effort that lead to quasi-renewable energy recovery, or energy that would otherwise by radiated as waste environmental heat, will have a far-reaching impact on the world's energy consumption, including lowering the U.S. dependence on foreign oil. Next to solar energy, waste heat recovery is the most available secondary power source.