Waste heat is often dumped into the environment and there have not been many cost-effective ways so far to harness it especially if it is of a low grade. Thermal radiation is the predominant form of heat transport between Space and Earth but it is often not considered to be efficient for waste heat applications. Here, we utilize the concept of non-imaging optics to enhance the capture of waste heat from a hot object in the form of thermal radiation. We designed and fabricated a compound parabolic concentrator (CPC) that is purely reflective in the mid-infrared using geometric non-imaging optics. With the CPC present, in between a hot plate and a target separated 10 cm apart under ambient conditions, we were able to increase the temperature of the target by as much as 20 oC. At the same time, our simulations and experiment demonstrate remarkable improvement in thermoelectric (TE) efficiency and output power compared to a bare TE exposed to the same radiative heat flux. Our work serves as a proof-of-concept for demonstrating the potential to collect waste heat remotely using pure thermal radiation.