Solar Power at Night
7 January 2008, 08:21
Categories: smt-energy-photovoltaic optics--photonics
Idaho National Laboratory (INL) reports that research conducted in conjunction with partners at Microcontinuum Inc. (Cambridge, MA) and Patrick Pinhero of the University of Missouri is promising a method for developing cheap solar energy technology that could be imprinted on flexible materials and still draw energy after the sun has set.
The technology uses a special manufacturing process to stamp tiny square spirals, or “nanoantennas”, of conduction metal onto a sheet of plastic. The nanoantennas absorb energy in the infrared part of the spectrum, just outside the range of what is visible to the eye. Since the sun radiates a lot of infrared energy, some of which is soaked up by the earth and later released as radiation for hours after sunset, nanoantennas can take in energy from both sunlight and the earth’s heat, with higher efficiency than conventional solar cells.
The team estimates individual nanoantennas can absorb close to 80 percent of the available energy in comparison to current commercial solar panels which usually transform less that 20 percent of the usable energy that strikes them into electricity; this is even more impressive than the 30% conversion rate offered by the recently discussed development of nano flakes by SunFlake.
While the energy can be harvested, the scientists have found no solution yet to convert the energy into electricity. According to the scientists, “more technological advances” are necessary to turn this vision into reality. 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.
Posted by: The Editors
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