The thermal metamaterial was developed in research aimed at efficiently harvesting waste heat from power plants and factories. (Purdue University/Sean Molesky)

An international research team has used a thermal metamaterial to control the emission of radiation at high temperatures, an advance that could bring devices able to efficiently harvest waste heat from power plants and factories. Thermophotovoltaic devices that generate electricity from thermal radiation might be adapted to industrial pipes in factories and power plants, as well as on car engines and automotive exhaust systems, to recapture much of the wasted energy.

The thermal metamaterial – nanoscale layers of tungsten and hafnium oxide – was used to suppress the emission of one portion of the spectrum while enhancing emission in another. The technique used to achieve thermal suppression and enhancement is fundamentally different from existing thermal engineering approaches, harnessing a phenomenon called topological transitions.