Quantum Physics Unlocks Hidden Energy for a Cleaner Future

BY RICE UNIVERSITYNOVEMBER 23, 2024

Using quantum physics, researchers at Rice University designed a highly efficient thermal emitter for turning heat into electricity. With potential applications in renewable energy, industry, and even space exploration, this innovation promises a cleaner and more sustainable future. Credit: SciTechDaily.com

A breakthrough at Rice University enhances thermophotovoltaic systems with a new thermal emitter design, achieving over 60% efficiency.

Researchers at Rice University have developed an innovative way to enhance thermophotovoltaic (TPV) systems, which convert heat into electricity using light. Drawing inspiration from quantum physics, engineer Gururaj Naik and his team designed a highly efficient thermal emitter that works within realistic design constraints.

A new thermal emitter developed by Rice University engineers composed of a tungsten metal sheet, a thin layer of a spacer material and a network of silicon nanocylinders promises efficiencies of over 60%. Credit: Gustavo Raskosky/Rice University

Impact on Sustainable Energy and Economy

This breakthrough has the potential to advance thermal energy storage, offering an affordable and scalable alternative to batteries for grid-scale energy solutions. More broadly, efficient TPV systems could drive renewable energy adoption, a crucial step toward achieving net-zero emissions. Additionally, improved TPV technologies could significantly reduce industrial waste heat, making manufacturing processes more sustainable. Currently, 20-50% of the heat used in producing consumer goods is wasted, resulting in over $200 billion in annual economic losses in the United States alone.

TPV systems involve two main components ⎯ photovoltaic (PV) cells that convert light into electricity and thermal emitters that turn heat into light. Both of these components have to work well in order for the system to be efficient, but efforts to optimize them have focused more on the PV cell.

“Using conventional design approaches limits thermal emitters’ design space, and what you end up with is one of two scenarios: practical, low-performance devices or high-performance emitters that are hard to integrate in real-world applications,” said Naik, associate professor of electrical and computer engineering.

Breakthrough in Thermal Emitter Design

In a new study published on November 21 in npj Nanophotonics, Naik and his former Ph.D. student Ciril Samuel Prasad ⎯ who has since earned a doctorate in electrical and computer engineering from Rice and has taken on a role as a postdoctoral research associate at Oak Ridge National Laboratory ⎯ demonstrated a new thermal emitter that promises efficiencies of over 60% despite being application-ready.

“We essentially showed how to achieve the best possible performance for the emitter given realistic, practical design constraints,” said Prasad, who is the first author on the study.

Gururaj Naik. Credit: Gustavo Raskosky/Rice University

Enhancing Emitter Performance Through Quantum Physics

The emitter is composed of a tungsten metal sheet, a thin layer of a spacer material and a network of silicon nanocylinders. When heated, the base layers accumulate thermal radiation, which can be thought of as a bath of photons. The tiny resonators sitting on top “talk” to each other in a way that allows them to “pluck photon by photon” from this bath, controlling the brightness and bandwidth of the light sent to the PV cell.

“Instead of focusing on the performance of single-resonator systems, we instead took into account the way these resonators interact, which opened up new possibilities,” Naik explained. “This gave us control over how the photons are stored and released.”

This selective emission, achieved through insights from quantum physics, maximizes energy conversion and allows for higher efficiencies than previously possible, operating at the limit of the materials’ properties. To improve on the newly achieved 60% efficiency, new materials with better properties would need to be developed or discovered.

Implications for Energy Conversion Technologies

These gains could make TPV a competitive alternative to other energy storage and conversion technologies like lithium-ion batteries, particularly in scenarios where long-term energy storage is needed. Naik noted that this innovation has significant implications for industries that generate large amounts of waste heat such as nuclear power plants and manufacturing facilities.

“I feel confident that what we have demonstrated here, coupled with a very efficient low bandgap PV cell, has very promising potential,” Naik said. “Based on my own experience working with NASA and launching a startup in the renewable energy space, I think that energy conversion technologies are very much in need today.”

Potential Applications in Space and Beyond

The team’s technology could also be used in space applications such as powering rovers on Mars.

“If our approach could lead to an increase in efficiency from 2% to 5% in such systems, that would represent a significant boost for missions that rely on efficient power generation in extreme environments,” Naik said.

Reference: “Non-Hermitian selective thermal emitter for thermophotovoltaics” by Ciril Samuel Prasad, and Gururaj V. Naik, 21 November 2024, npj Nanophotonics.
DOI: 10.1038/s44310-024-00044-3

The research was supported by the National Science Foundation (1935446) and the U.S. Army Research Office.

https://scitechdaily.com/quantum-physics-unlocks-hidden-energy-for-a-cleaner-future/