Between 50% and 60% of energy consumed in the United States is lost to the environment as waste heat. There is a large opportunity to convert waste heat to electricity, especially in the U.S. industrial sector. Harvesting waste heat through solid-state devices offers a path to recovering this resource. However, current waste heat power generation research focuses mainly on boilers, steam turbines, and generators that are not compatible with most industrial equipment. Development of technologies for direct generation of electricity from waste heat will help improve the overall energy efficiency of the industrial sector.
Project Innovation + Advantages:
The Columbia University team is developing a proof-of-concept solid-state solution to generate electricity from high-temperature waste heat (~900 K) using thermal radiation between a hot object placed in extreme proximity (<100 nm) to a cooler photovoltaic (PV) cell. In this geometry, thermal radiation can be engineered such that its spectrum is quasi-monochromatic and aligned with the PV cell’s bandgap frequency. In this case, it is estimated that electricity can be generated with a conversion efficiency beyond 25% and with a power density that could greatly outperform currently available thermal photovoltaic devices and other thermoelectric generator designs. To overcome the significant challenge of maintaining the proper distance between a hot side emitter and a cooler PV junction to prevent device shorting, the team will develop microelectromechanical actuation systems to optimally orient the PV cell. By providing a universal solid-state solution that can, in principle, be mounted and scaled to any hot surface, this technology could help retrieve a significant fraction of heat wasted by U.S. industries