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.
The researchers studied the behavior of various materials — including gold, manganese and copper — under infrared rays and used the resulting data to build computer models of nanoantennas.
They found that with the right materials, shape and size, the simulated nanoantennas could harvest up to 92 percent of the energy at infrared wavelengths.
They said that infrared rays create alternating currents in the nanoantennas that oscillate trillions of times per second, requiring a component called a rectifier to convert the alternating current to direct current and today’s rectifiers can’t handle such high frequencies.
A nanoscale rectifier suited for this application in fact would need to be about 1,000 times smaller than current commercial devices and will require new manufacturing methods, according to the scientists.
“At this point, these antennas are good at capturing energy, but they’re not very good at converting it,” says INL engineer Dale Kotter, “but we have very promising exploratory research under way.” Kotter and Novack are also exploring ways to transform the high-frequency alternating current (AC) to direct current (DC) that can be stored in batteries.
“Every process in our industrial world creates waste heat,” says INL physicist Steven Novack. “It’s energy that we just throw away.” Novack led the research team, which included INL engineer Dale Kotter, W. Dennis Slafer of MicroContinuum, Inc. (Cambridge, Mass.) and Patrick Pinhero, now at the University of Missouri.