‘We’ve all been taught that this doesn’t happen’
From the University of Michigan
A dramatic and surprising magnetic effect of light discovered by University of Michigan researchers could lead to solar power without traditional semiconductor-based solar cells.
The researchers found a way to make an “optical battery,” said Stephen Rand, a professor in the departments of Electrical Engineering and Computer Science, Physics and Applied Physics.
In the process, they overturned a century-old tenet of physics.
“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, an author of a paper on the work published in the Journal of Applied Physics. “It’s a very odd interaction. That’s why it’s been overlooked for more than 100 years.”
Light has electric and magnetic components. Until now, scientists thought the effects of the magnetic field were so weak that they could be ignored. Rand and his colleagues 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. Under these circumstances, the magnetic effects develop strength equivalent to a strong electric effect.
“This could lead 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.”
What makes this possible is a previously undetected brand of “optical rectification,” says William Fisher, a doctoral student in applied physics. In traditional optical rectification, light’s electric field causes a charge separation, or a pulling apart of the positive and negative charges in a material. This 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.
Rand and Fisher found that under the right circumstances and in other types of materials, the light’s magnetic field can also create optical rectification.
“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,” Fisher said.
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.”
In experiments this summer, the researchers will work on harnessing this power with laser light, and then with sunlight.
The paper is titled “Optically-induced charge separation and terahertz emission in unbiased dielectrics.” The university is pursuing patent protection for the intellectual property.
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Obviously, this is still in the theory/conceptual stages. I wouldn’t get too excited just yet. A practical application of this concept is still years, if not decades off. But, if it could work, it would be a boon for solar power.
Sounds like MRI – something well known already.
“Hey, Doc, we only need 1.21 gigawatts to power the flux capacitor!”
Ok, it sounds interesting, but as an useful power source…? not so sure…
polistra says: April 14, 2011 at 8:29 pm
“sounds to me like a piece of weapons research…”
Sorry, I think I did not indicate my idea clearly.
I do not expect that it is physically probable to create or to focus natural light to the required level onto a optical fiber without a space based magnifying glass and a glass fiber made from unobtainium.
I though that if the physical action is reversible it should be easily demonstrable.
The ability to create an intense light source using only a piece of glass and some wire (no pump tube, no mirrors, no gasses, no filament and no semi-conductors) would be a real breakthrough. A permanent (in human terms) light bulb.
On the light as a weapon side; the United States already has a ship based laser that they publicly demonstrated last week (in the Pacific off the California coast) to smoke another boat (moving, bobbing etc.) at a great distance; also on the same day they demonstrated a land based high power free electron laser to destroy something else. Word is there FEL can get through 12 feet of steel in about 1 second and the ship based system is good to a distance of ‘miles not feet’.
I don’t think that this student’s work is any kind of “weapons research”, if it were you would not be hearing about it, yet. Remember how long it took before the laser gyroscope became ‘public’, that was “weapons research”
Interesting post. But if, in fact, there were materials that would be more sensitive to sunlight (being far more diffuse than 10 million watts per square centimeter) so as to create this magnetic effect, wouldn’t we see electricity flowing in those materials already? I don’t think that such materials really exist. But who knows, we may find some.
I think working with lasers makes you crazy, anyway. Just kidding.
This just goes to show that the more convoluted and complicated these solar schemes are the more expensive and unreliable they become. So in that spirit I’ll see your magnetic glass fiber and raise you one Trombe wall. As always, with solar, low tech wins every single time.
tom gannett says:
April 14, 2011 at 7:01 pm
> I smell another cold fusion story coming.
Glad to oblige.
Last week the Swedish Skeptical Society (sorta like the US version, but without the record of denying climate skeptics respect) validated a Rossi E-cat device, see
http://www.nyteknik.se/nyheter/energi_miljo/energi/article3144827.ece which says, in part:
Perhaps readers are forgetting the large advances made between the discovery that radio waves can be transmitted over a distance, and the development of today’s cell phones. The work is closer to Marconi and Tesla than Vodafone.
Give the guys a break! It was embarassing to read some of the above. Have you ever worked out the W/m^2 of a well made small laser? And that for a material not even slightly optimised? Ask a HAM radio operator to show you the size, power and efficiency of an early radio transmitter.
What’s the point of having a website for new and interesting technologies (for skeptics, no less) if all you think about is diminishing new ideas! These are hardly the first people to demonstrate that there are fundamental misunderstandings about life, the universe and everything held high. Perhaps read Lee Smolin’s book on problems with physics. There is a lot of room for improvement and this would be a good one.
There are evidently more minds than before accepting that there is some sort of ether, which obviously does not have the properties of a gas as was thought in Victorian times. One has to be very careful not to offend the mullahs of science so it is given various names that often include the word ‘continuum’.
Tesla had a very different understanding of what fills space. He was right on a couple of other things as people may recall, but he did not demonstrate anything I would accept to support his understanding of it. Maybe he was wrong, but there is no shortage of ideas. So we should stand on middle ground when looking at breakthrough understandings.
Light, gravity and electricity are probably waves through some etherial field or material of indeterminate, perhaps directly undetectable ‘continuum’. This is hardly a new idea and appeared in books over a century ago. As electricity and magnetism are directly linked they can be viewed as ‘one’. To find that light interacts with selected materials creating both electrical and magnetic effects is surely not a surprise.
Congratulations to Rand and Fisher. May they overturn the dogma that clutters the minds of so many, and establish sound principles in its place. The principles do not have to be narrow and exclusive or in the possession of an elite, particularly and most dangerously, a self-appointed one.
Is the energy density mentioned available near the sun? What is the falsefiable statement in this case?
Well said Crispin in Johannesburg.
Come on, the allusion to solar power is the standard PhD student pick-up line at a bar. If you are forced to describe your work to a vaguely attractive girl are you going to say
“I am working on optically induced magnetism in solids”
to which she replies
“goodbye”
Or do you say
“I am working on improving solar energy for the benefit of all humanity”
at which point she might not walk away. Which for most PhD physics students is a win. Anyone who has been a PhD physics student has either (a) done this or (b) seen their friends do it. No matter how tenuous or far-off the link to something a chick might dig, you play it up. Back in the department conferences no one gives a stuff, because they think it is cool, just because it is.
on April 14, 2011 at 6:43 pm
Jonathan said:
“Simplifying the solar radiation on Earth to 1kw/m^2, we obtain 0.1w/cm^2.
(10 million w/cm^2) / (0.1 w/cm^2) = 100 million suns of focusing power.
I think that “sunlight is not this intense on its own” is a vast understatement.”
No, the sunlight can do that indeed. Just put their 1cm^2 fiber into the focus of one lens or parabolic mirror which focuses a 1000m^2 area (sarc).
The real problem is: what’s the outgoing energy we could get from that so wide device?
“The paper is titled Optically-induced charge separation and terahertz emission in unbiased dielectrics.
That reminds me of the lab engineer who needed a mirror in his lab.
But there was no way he could get it into the budget. So he changed it to “Optical reflector device” and there was no problem.
Aliens figured this stuff out a long time ago.
The energy density is not a problem .
Take 1 kw/m² (just the usual sunny day) and concentrate all the rays on a surface of 1 mm² .
You’ll still get “only” 1 kw in total but the energy density on this 1 mm² became 1 kw/mm² what gives in other units 1000 MW/m² or 0.1 MW/cm² .
To get their 10 MW/cm² , they need a factor 100 over the above focusing power so they need to focus 1m² on a square of 0.1 mm x 0.1 mm .
This is hard but not unfeasible .
What I suspect is that producing a lens (or a curved reflector surface) with such an accuracy would cost far more than the value of a power generating capacity of 1 kw .
Of course creating a lens or surface 1000 times bigger with the same accuracy would cost more than 1000 times the price of a 1 m² module so there would be no economies of scale .
So if this theory is true , it would just be a more expensive alternative to the traditional photovoltaic cell .
And as we know that photovoltaic cells are already 10 times more expensive than coal or gas alternatives , this “new” technology would become economically interesting the day we run out of sand .
I don’t expect it happening in the next few millions of years .
10,000,000 watts per cm2 is a crazy amount of concentration.
Until and unless this drops by many orders of magnitude, it will be no more significant to actually doing anything than those ftl quantum effect demonstrations have been until now.
“Intense magnetization can be induced by intense light and then it is ultimately capable of providing a capacitive power source.”
I find that statement odd. Capacitors work based on an electric field. They have two (or more plates) in close proximity, separated by an insulator (dielectric). Differences in electron density between the two plates result in energy stored in the electric field.
Inductors are the magnetic equivalent of capacitors and they store energy in the form of a current flow induced by the magnetic field.
Surely to capture this magnetic energy, an inductor will be required to generate a current flow in order to charge the capacitance although I would have thought it would be easier to simply deliver the current derived from the magnetic field straight into a battery.
Anyway as others have pointed out, the light density required is so extreme that this is unlikely to ever become practical, even if it is an interesting discovery in the field of physics.
I believe the book by Lee Smolin is “Three Roads to Quantum Gravity” which discusses space itself as having a Planck size. The theory is called Loop quantum gravity and has interesting implications. I recommend the book for anyone with interests along this line. It also discusses some of the problems with string theory.
The book is about 10 years old but I have not found any follow up. Maybe someone here has followed this more closely.
A factor of great importance in laser work is the focus. During my foray of research into it, we had (a) an inquiry from a wheat farmer who wanted to cut his stubble to the ground by sweeping a laser beam through it from a central point (b) a maker of coconut ice candy whose cutting knives would clog up, better to use a laser and slice with high heat – workable (c) a major maker of cardboard boxed, whose knives also used to clog up – workable, but expensive … and many others. The point in common was a confusion of energy density in the tiny voulme of a fine focus, with the false thought that such power and cutting ability could be applied over large distances.
Weapons reserach has seen lasers in large aircraft, but the limit is the weight of the power supply and (presumably) slabs, plus the refrigeration system. Maybe that’s why they are concentrating on ships. Not so familiar with the free electron laser, but a 12 foot sheet of steel seems highly improbable for practicality. One would have to keep the focus in exactly the same spot, which is hard to imagine on bobbing ships.
The lead article is quite unclear. I can’t envisage energy capture using capacitance principles, but we need a better description. Don’t write it off until there is one. That’s anti-science.
Or Steve Martin’s bit about “How to be a Millionaire, and never pay taxes”
First… get a million dollars.
Right.
Reminds me of the formula for time travel –
“First you start with a small black hole …”
The Sun’s surface puts out 63,200,000 watts/m2 or 6,320 watts/cm2 (per second).
So the energy levels quoted in the article are 1,500 times more powerful than the surface of the Sun.
Very Interesting…. How does this fit with the Plasma Universe theory/idea. Where electo magnetic interactions have more effect on the motions of Galaxies than does gravity?
…… This is quite astounding.
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TomVonk says:
April 15, 2011 at 4:22 am
The energy density is not a problem.
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No, it certainly still is. You can’t get past the fact that to capture a reasonable amount of low-density solar energy (compared to fossil or nuclear), you’ll need a comparatively enormous area & amount of hardware to do so.
You can’t cheat simple physical realities of low-power-density sunlight, and in addition to that, cloudy days or nighttime.
Sounds like “anal rectification” instead of “optical rectification” to me and another grasp for grants.
See: (It’s an hour long. Watch all of it.)
http://www.youtube.com/watch?v=V7jKL2-B0QA&feature=player_embedded
Photonic energy induces charge separation in water – this is a much more prominent
effect than heating the water by photons.
Another thought:
“Gravity lenses”.
“Astronomers assigned the phenomena to gravity only because they were already in search of such “proofs.” They needed the bending to be caused by gravity, so they ignored the more likely explanations. As in so many other instances, they let the theory determine the data. Instead of having data, and then developing a theory to contain it, they had a theory, and then went in search of data to support it. ”
http://milesmathis.com/lens.html
see also
http://tallbloke.wordpress.com/2011/02/09/ed-dowdye-light-bending-proposal/
DirkH says:
April 15, 2011 at 6:38 am
“Photonic energy induces charge separation in water – this is a much more prominent
effect than heating the water by photons. ”
Well, i wrote it that way because that’s how Dr. Gerald Pollack explained it in the video but maybe it’s not simply the photonic energy but the electromagnetic effect of light that is suggested by Stephen Rand.
Well DirkH to be fair you should have some reason to be proposing hypotheses (data if you will) and then test a set of possible hypotheses to see which best survives the data that is then collected to invalidate them.
Developing a hypothesis solely from data observations is the inductivist trap. On the other hand, searching for data to support a hypothesis is the cherry-picking trap.