In response to the NASA STTR solicitation topic T3.01, "Energy Harvesting, Transformation and Multifunctional Power Dissemination", Advanced Cooling Technologies, Inc. (ACT) and Carnegie Mellon University (CMU) propose to develop a thermo-radiative cell to harvest energy from waste heat, for example, from radiators. Currently NASA's Top Technical Challenge is the need to "increase available power". Additionally, NASA has a Grand Challenge as "Affordable and Abundant Power" for NASA mission activities. The thermo-radiative cell technology uses semiconductor p-n junctions, similar to the photovoltaic cell but with smaller band gap semiconductor, to convert heat to electricity. This technology makes use of the extremely cold dark universe (~3K) as the natural heat sink and low-grade waste heat (~50-100℃) as the heat source. The imbalance of the thermal radiation emitted and absorbed by the cell will cause the imbalance of the charge carrier motion in the p-n junction, i.e., generating electrical power. The overall technical objective of Phase I and Phase II projects is to develop a thermo-radiative cell system that can generate practically usable power as supplementary power for the electronics on space vehicles, platforms or habitats. During Phase I, ACT will fabricate a cryogenic system to investigate the performance the thermo-radiative cell made of commercial available InSb, HgCdZnTe, PbSe, or InAs wafers. The cryogenic system will use liquid nitrogen to create a stable low temperature environment. Performance investigation includes the power density and energy efficiency at different heat source temperatures for the non-optimized cell material component and structure in Phase I.