Solar Breakthrough Could Provide Power Without Solar Cells

An anonymous reader tips a University of Michigan news release about the creation of what's being called an "optical battery" that could lead to the use of solar power without traditional solar cells (abstract). Quoting: "Light has electric and magnetic components. Until now, scientists thought the effects of the magnetic field were so weak that they could be ignored. What Rand and his colleagues found is 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.'"

Comments

The future's so bright...

[Itesh]

I gotta wear shades!

Beyond the theoretical limit

[Geoffrey.landis]

The press office at U. Michigan has gone a long way from what they actually did to what they are speculating might be theoretically be possible. What they actually did was to predict a theoretical effect which has not yet been demonstrated. The press office then suggests that if you concentrate sunlight by a factor of a hundred million-- about seven hundred times higher than the theoretical concentration limit-- that this as-yet-unidentified material might be able to convert the light into electricity.
This is a bit speculative. They've predicted an interesting theoretical effect. Let's keep it at that, which is a nice piece of work, and leave the speculation to science fiction writers (like me).

Re:Beyond the theoretical limit

[Mt._Honkey]

There's a theorem in imaging that says you cannot focus a light source to create a beam any more intense then at the surface of what is emitting the light. A consequence of this is that you cannot heat something to hotter than the surface temperature of the sun by concentrating sunlight in any way, even if you had a lens the size of the solar system. The spot size that you get will just keep getting bigger.

Incidentally if you were able to do this it would violate the 2nd law of thermodynamics, because you would be moving energy from a cooler object to a warmer one without doing any work, thus decreasing the total entropy of the universe.

Re:I've been reading about solar breakthroughs

[Anonymous Coward]

The trouble is that it's still cheap to get fossil fuels.

Re:I've been reading about solar breakthroughs

[Compaqt]

It's awesome that they are (apparently) directly generating electricity. Much better than the quaint method of boiling water to turn turbines.

Wait, what?

[pushing-robot]

Electromagnetism consists of equal parts electricity and magnetism?

You mean... That fool Maxwell was right?

Re:Wait, what?

[pclminion]

Isn't a static electric charge an example of E without M?

What is a static charge? I can choose a reference frame where the charge is in motion, and thus produces a magnetic field. If you look carefully at the fundamental equations of electromagnetism, you see things like "the force on the charge is proportional to the velocity of the charge," and "the induced magnetic field is proportional to the rate of change of magnetic flux."

Both of these statements immediately imply the question in whose reference frame are we to measure the velocity of the charge or the rate of change of magnetic flux? In one frame to another the velocity is different, as is the rate of change of flux. But no matter what reference frame you pick, the particle does the same thing. This means that the electrical force and magnetic force are actually the same force, but they appear to be different when you choose some particular reference frame in which to measure them. You could have chosen a frame in which both fields took on different values, yet the net effect on the particle is the same.

It is relativity which causes the apparent splitting of the one unified force (electromagnetism) into two different forces (electricity and magnetism). You cannot have one without the other, or rather, you can have as much or as little of one as you want, depending what frame you measure in.

They are the same and can't be separated.

Don't hold your breath.

[mark-t]

This is still all theoretical, and to the best of my understanding has not been verified by actual working prototypes.

I'm really surprised that the article didn't mention "5 years" as a time scale for when this will be viable, since that's the typical duration mentioned in these sort of articles --- far enough in the future that most will have forgotten about it by the time we get there, but near enough to still feel like it's worth anticipating (in other words, the perfect length of time for a project that needs funding to continue, but may never actually produce desired results).

Satellites not shipping products ...

[perpenso]

I agree with the general idea that there are lots of exaggerated claims and promises. I view that as most likely coming from people looking for grants or venture capitalists to fund their projects.

However I would not keep an eye to the shipping products to judge feasibility, I would keep an eye on satellites. Break throughs like the one in this story might first appear in the environment of much higher solar intensity found in space.

Re:I've been reading about solar breakthroughs

[by (1706743)]

Yeah, it's amusing that nuclear power reactors can use the same method as a 1800's steam engine.

Re:Solar power

[geekoid]

Wait till morning.

Re:I've been reading about solar breakthroughs

[smelch]

Yes, what would be great is if fossil fuels were really expensive and we actually had an energy crisis. We won't get efficient panels until all the factories are shut down.

Re:I've been reading about solar breakthroughs

[icebraining]

That's because they don't pay their due externalities.

Re:I've been reading about solar breakthroughs

[Belial6]

30 years ago, it took more energy to produce a solar panel then what it would produce in it's lifetime. Today that is not the case. That achievement alone is monumental. Your problem is that you can't see the connection between the announcement and the release of these products.

Re:I've been reading about solar breakthroughs

[Rei]

I've been reading about solar breakthroughs for 30 years

30 years ago, photovoltaic panels cost almost $40 per watt.
Today, the cheap ones are about $2 per watt.

Mods, how is ignorance insightful?

Theoretical limit to solar concentration

[Geoffrey.landis]

I wasn't aware there was a theoretical concentration limit. Where did you get that from and what's the rationale for it?

The theoretical concentration limit is straightforward-- it comes from the fact that the sun has a non-zero solid angle. Basically, a concentrator works by increasing the fraction of the sky that's filled by the sun, and the best you can do is to make the light come from the whole sky. (Well, there's also a factor of n, the refractive index).

The book Solar Electricity by T. Markvart gives a calculation (page 237-- it's available on googlebooks)

Re:I've been reading about solar breakthroughs

[demonbug]

WOOOOOOOSH

Yes, you're right, sometimes the steam lines leak.