New Technics For Solar Energy 1
Solar Power Without Solar Cells By a Hidden Magnetic Effect of Light
Science can be pretty crazy sometimes, and the craziness has allowed researchers to find a new discovery that could lead to solar power without the usual semiconductor-based solar cells.
Researchers in the departments of Electrical Engineering and Computer Science, Physics and Applied Physics in the University of Michigan, led by Professor Stephen Rand, discovered a dramatic and surprising magnetic effect of light. They found a way to make an “optical battery,” overturning a century-old tenet of physics.
As you may know, light has electric and magnetic components. And up until now, scientists thought the effects of the magnetic field were so weak that they could be ignored. The researchers found that at the right intensity, when light is traveling through a material that does not conduct electricity, the light field can generate magnetic effects that are 100 million times stronger than previously expected. With these conditions, the magnetic effects stimulate strength equal to a robust electric effect, leading to a new kind of solar cell without semiconductors and without absorption to produce charge separation,” Rand said. “In solar cells, the light goes into a material, gets absorbed and creates heat. Here, we expect to have a very low heat load. Instead of the light being absorbed, energy is stored in the magnetic moment. Intense magnetization can be induced by intense light and then it is ultimately capable of providing a capacitive power source.”
A previously undetected brand of “optical rectification” makes this ‘magic’ possible, according to William Fisher, a doctoral student in applied physics and the the co-author of the study published recently in the Journal of Applied Physics.
In traditional optical rectification, light’s electric field causes a charge separation that sets up a voltage, similar to that in a battery. This electric effect had previously been detected only in crystalline materials that possessed a certain symmetry, but found now that the light’s magnetic field can also create optical rectification under the right circumstances and in other types of materials.
“It turns out that the magnetic field starts curving the electrons into a C-shape and they move forward a little each time,” Fisher said. “That C-shape of charge motion generates both an electric dipole and a magnetic dipole. If we can set up many of these in a row in a long fiber, we can make a huge voltage and by extracting that voltage, we can use it as a power source.”
The light must be shone through a material that does not conduct electricity, such as glass. And it must be focused to an intensity of 10 million watts per square centimeter. Sunlight isn’t this intense on its own, but new materials are being sought that would work at lower intensities, Fisher said. “In our most recent paper, we show that incoherent light like sunlight is theoretically almost as effective in producing charge separation as laser light is.”
“You could stare at the equations of motion all day and you will not see this possibility. We’ve all been taught that this doesn’t happen,” said Rand. “It’s a very odd interaction. That’s why it’s been overlooked for more than 100 years.”
This new technique could make solar power cheaper, the researchers say. They predict that with improved materials they could achieve 10 percent efficiency in converting solar power to useable energy. That’s equivalent to today’s commercial-grade solar cells.
“To manufacture modern solar cells, you have to do extensive semiconductor processing,” Fisher said. “All we would need are lenses to focus the light and a fiber to guide it. Glass works for both. It’s already made in bulk, and it doesn’t require as much processing. Transparent ceramics might be even better.”
The University of Michigan is pursuing patent protection for the intellectual property.
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Original Publishing Date: 06-06-2011
Republishing Date: 23-07-2016
Republishing Date: 20-12-2016