Flexible Nanoantenna Arrays
|Photo Credit: Idaho National Laboratory
Researchers have devised an inexpensive way to produce plastic sheets containing billions of nanoantennas that collect heat energy generated by the sun and other sources. The researchers say that the technology, developed at the U.S. Department of Energy's Idaho National Laboratory (INL), is the first step toward a solar energy collector that could be mass-produced on flexible materials.
While methods to convert the energy into usable electricity still need to be developed, it is envisioned that the sheets could one day be manufactured as lightweight "skins" that power products such as hybrid cars or iPods with potentially higher efficiency than traditional solar cells. The nanoantennas also have the potential to act as cooling devices that draw waste heat from buildings or electronics without using electricity.
The nanoantennas target mid-infrared rays, which the Earth continuously radiates as heat after absorbing energy from the sun during the day. In contrast, traditional solar cells can only use visible light, rendering them idle after dark. Infrared radiation is an especially rich energy source because it also is generated by industrial processes such as coal-fired plants.
More technological advances are needed before the nanoantennas can funnel their energy into usable electricity. The 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. Today's rectifiers can't handle such high frequencies. Another possibility is to develop electrical circuitry that might slow down the current to usable frequencies.
If these technical hurdles can be overcome, nanoantennas have the potential to be efficient harvesters of solar energy. Because they can be tweaked to pick up specific wavelengths depending on their shape and size, it may be possible to create double-sided nanoantenna sheets that harvest energy from different parts of the sun's spectrum.
Cited from RenewableEnergyWorld.com.