Illustration of nanopillars used in a new design to efficiently convert heat energy into electricity.
Credit: S. Kelley/NIST
Researchers at the National Institute of Standards and Technology (NIST) have fabricated a novel device that could dramatically boost the conversion of heat into electricity. If perfected, the technology could help recoup some of the heat energy that is wasted in the U.S. at a rate of about $100 billion each year.
The new fabrication technique — developed by NIST researcher Kris Bertness and her collaborators — involves depositing hundreds of thousands of microscopic columns of gallium nitride atop a silicon wafer. Layers of silicon are then removed from the underside of the wafer until only a thin sheet of the material remains. The interaction between the pillars and the silicon sheet slows the transport of heat in the silicon, enabling more of the heat to convert to electric current. Bertness and her collaborators at the University of Colorado Boulder reported the findings online March 23 in Advanced Materials.
Once the fabrication method is perfected, the silicon sheets could be wrapped around steam or exhaust pipes to convert heat emissions into electricity that could power nearby devices or be delivered to a power grid. Another potential application would be cooling computer chips.
Using Nanopillars to Efficiently Convert Heat into Electricity
By growing nanopillars above a silicon membrane, NIST scientists and their colleagues have reduced heat conduction by 21% without reducing electrical conductivity, a result that could dramatically boost the conversion of heat energy into electrical energy. In solids, heat energy is carried by phonons, periodic vibrations of atoms in a crystal lattice. Certain vibrations of the phonons in the membrane resonate with those in t ..
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