Low Cost Thermoelectric Energy Harvesting for Efficient Power Generation

This SBIR Phase I project will address the technological risks in bringing silicon-based nanostructured thermoelectric materials from a proven laboratory concept to a scalable prototype device. Thermoelectric materials offer great promise for energy efficiency through waste heat recovery in military aircraft applications. They are compact, lightweight, highly reliable and virtually maintenance free. Implementation to date has been precluded by the high cost per watt and the low design temperature of existing thermoelectric materials. Alphabet Energy’s silicon nanowire thermoelectric materials, a breakthrough from the Lawrence Berkeley National Laboratory, use low-grade silicon as a raw material and a manufacturing process that utilizes standard semiconductor fabrication tools and facilities. This leads to a device cost in the order of 20¢/Watt, 50-100 times cheaper than existing thermoelectrics. Silicon nanowire thermoelectric materials have been tested at temperatures up to 600C without loss of performance and we project that they will continue to perform at temperatures up to 1000C. The currently measured ZT of above 1 at 400-600C temperature gradient provides an ~10% efficient device. We have an established pathway through optimization of the roughness and morphology of the nanowires to raise ZT above 2 and achieve much higher efficiencies of 20% or more. BENEFIT: Beyond applications in aircraft energy harvesting and other military applications, Alphabet Energy''s technology will open up the $200 billion potential world market for civilian waste heat recovery. Up to 17% of the US''s electricity needs could be provided by power generated from heat in exhaust streams from power plants, heavy manufacturing and transportation, thus eliminating 430 million tonnes of US carbon dioxide emissions.