Nanoantennas envisioned as possible replacement for solar cells
Imagine the possibilities of harvesting waste heat and converting it into electricity. Computer processors could be the source of power for their own cooling devices and solar cells could become dramatically more efficient by leveraging energy that is not being used today. If everything goes right, nanoantennas could even replace solar cells one day, researchers believe.
Scientists from the U.S. Department of Energy's Idaho National Laboratory believe that plastic sheets containing billions of nanoantennas that collect heat energy generated by the sun and other sources could dramatically improve the use of a type of energy we are all aware of, but have no use for so far – heat. According to research results that will be presented on August 13 at the American Society of Mechanical Engineers 2008 2nd International Conference on Energy, the sheets could one day be manufactured as lightweight "skins" that power everything from hybrid cars to iPods with higher efficiency than traditional solar cells.
While described by the authors of research as solar energy, the approach does not focus on collecting sunlight, but flexible nanoantenna arrays that capture abundant solar energy mid-infrared rays radiated by the Earth as heat after absorbing energy from the sun during the day. The clear advantage of this thought is that energy can be generated at all times and not just during times when sun light is available. The scientists said that infrared radiation is an especially rich energy source because it also is generated by industrial processes such as coal-fired plants.
The nanoantennas are tiny gold squares or spirals set in a specially treated form of polyethylene, a material used in plastic bags. While others have successfully invented antennas that collect energy from lower-frequency regions of the electromagnetic spectrum, such as microwaves, infrared rays have proven more elusive. Part of the reason is that materials' properties change drastically at high-frequency wavelengths.
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