Low quality heat constitutes a 2 TW untapped source of energy in the US. High coefficient of performance thermoelectrics with a figure of merit (ZT) exceeding 1, can potentially harness approximately 4.3% of this waste heat and add up to 23% to the current electricity production at zero additional carbon or noise emission. Existing commercial thermoelectric materials based on Bi2Te3 possess ZT~1 at room temperatures but are not scalable due to the extremely low abundance of Te. The University of Illinois will collaborate with MC10, Inc. (a startup) to develop an economic and highly scalable approach to fabricate flexible thermoelectric junctions based on silicon nanotubes and optimize the energy conversion efficiency. The end of phase deliverable is a 1 square inch flexible thermoelectric module with effective ZT over 1.2. Such flexible modules will convert waste heat in power plants, data centers and automobiles.