Researchers at Rice University have unveiled a groundbreaking thermal emitter that significantly boosts the efficiency of thermophotovoltaic (TPV) systems, which convert heat into electricity using light. This development could pave the way for more affordable alternatives to batteries on a large scale and facilitate the transition to a zero-emission world.
Traditional designs for thermal emitters have often been constrained, resulting in either low-performance devices or high-performance emitters that are challenging to integrate into practical applications. By leveraging principles from quantum physics, engineer Gururaj Naik and his team created a thermal emitter that achieves high efficiency within realistic design parameters.
“Essentially, we demonstrated how to achieve the best possible performance from an emitter while considering realistic, practical design constraints,” said Cyril Samuel Prasad, the study's lead author and a former graduate student of Naik.
The new thermal emitter consists of a sheet of tungsten, a thin layer of separating material, and a network of silicon nanocylinders. When heated, the base layers accumulate thermal radiation, likened to a bath of photons. Tiny resonators positioned on top interact in a manner that allows them to “capture photon after photon” from this bath, controlling the brightness and bandwidth of light sent to the photovoltaic cell.
“Instead of focusing on the performance of single resonator systems, we considered how these resonators interact, which opened new possibilities. This provided control over how photons are stored and released,” Naik explained.
This selective emission maximizes energy conversion, achieving higher efficiency than previously possible while operating at the limits of material properties. The new technology could render TPV a competitive alternative to other energy storage and conversion technologies, especially in scenarios requiring long-term energy storage.
“I am confident that what we have demonstrated, coupled with a highly efficient photovoltaic cell with a small bandgap, holds great promise. Based on my experience with NASA and launching a renewable energy startup, I believe energy conversion technologies are in high demand today,” Naik stated.
Moreover, this technology could find applications in space, such as powering Mars rovers. “If our approach can enhance the efficiency of such systems from 2% to 5%, it would provide a significant boost for missions that rely on effective electricity generation in extreme conditions,” Naik added.
This development also has the potential to recover waste heat from industrial processes, making them more sustainable. It is estimated that 20%-50% of the heat used for converting raw materials into consumer goods is wasted, costing the U.S. economy over $200 billion annually.