Solar Power without Solar CellsA dramatic and surprising magneticeffect of light discovere
Solar Power without Solar Cells
A dramatic and surprising magneticeffect of light discovered by University of Michigan1researcherscould lead to solar power without traditional semiconductor-based solar cells.The researchers found a way to make an“optical51 ,” said Stephen Rand, a professor in thedepartments of Electrical Engineering and Computer Science, Physics and AppliedPhysics.
Light has electric and magnetic52 .Until now, scientists thought the effect of the magnetic field were so weakthat they could be 53 . What Rand and his colleagues found isthat at the right intensity, when light is traveling through a material thatdoes not 54 electricity, the light field cangenerate magnetic effects that
are 100 million times stronger than previouslyexpected. Under these circumstances, the magnetic effects develop strength55 toa strong electric effect.
“This could lead to a new kind of solarcell without semiconductors and without absorption to produce charge separation,” Rand said. “In solar cells, the 56 goesinto a material, gets absorbed and creates heat. Here, we expect to have a verylow heat load2. Instead of the light being absorbed, energy is stored in themagnetic moment3. Intense magnetization can be induced by intense light andthen it is ultimately capable of providing a capacitive power 57 Whatmakes this possible is a previously undetected brand of “opticalrectification,” says William Fisher, a doctoral student in applied physics. Intraditional optical rectification, light's electric field causes a chargeseparation, or a pulling58of the positive and negative charges ina material. This sets up a voltage, similar to59in a battery.
Rand and Fisher found that under the rightcircumstances and in right types of materials, the light's magnetic field canalso create optical rectification. The light must be shone througha 60 thatdoes not conduct electricity, such as glass. And it must be focused to anintensity of 10 million watts per square centimeter8. Sunlight isn't this61 onits own, but new materials are being sought that would work at lowerintensities, Fisher said.
“In our most recent paper, we show thatincoherent light9 like sunlight is theoretically almost62effectivein producing charge separation as laser light is,” Fisher said.
This new63 couldmake solar power cheaper, the researchers say. They predict that with improvedmaterials they could achieve 10 percent efficiency in converting solar power touseable energy. That's equivalent to today's commercial-grade solar cells.
“To manufacture modem solar cells, youhave to do64 semiconductor processing,” Fisher said.“All we would need are lenses to focus the light and a fiber to guide it. Glassworks for65 .It's already made in bulk, and itdoesn't require as much processing. Transparent ceramics might be even better.”
51.A.disc
B.fiber
C.instrument
D.battery
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