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Subject: "New solar cell achives near 100% efficiency" Previous topic | Next topic
zewari
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Sat Oct-25-08 03:25 AM

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"New solar cell achives near 100% efficiency"


  

          

New solar cell material achieves almost 100% efficiency, could solve world-wide energy problems

http://www.tgdaily.com/content/view/39807/113/

Columbus (OH) - Researchers at Ohio State University have accidentally discovered a new solar cell material capable of absorbing all of the sun's visible light energy. The material is comprised of a hybrid of plastics, molybdenum and titanium. The team discovered it not only fluoresces (as most solar cells do), but also phosphoresces. Electrons in a phosphorescent state remain at a place where they can be "siphoned off" as electricity over 7 million times longer than those generated in a fluorescent state. This combination of materials also utilizes the entire visible spectrum of light energy, translating into a theoretical potential of almost 100% efficiency. Commercial products are still years away, but this foundational work may well pave the way for a truly renewable form of clean, global energy.


A complete study of the team's work appears in the current issue of "Proceedings of the National Academy of Sciences" (PNAS).


Fluorescence and phosphorescence

Traditional solar cell materials use a property called fluorescence to gather electricity. Energy from the sun strikes whatever material they are made of resulting in a momentary "dislodging" of electrons into an excited state. The excited electrons exist due to a property called fluorescence. They last only a dozen or so picoseconds (trillionths of a second) in this state, which is also called a "singlet state." The many picosecond dwell there is fairly typical among traditional solar cell material in use today.

The new material, which was accidentally discovered using supercomputers to determine possible theoretical molecular configurations, causes not only fluorescing electrons in the singlet state to be created, but also phosphorescing electrons in what's called a "triplet state."

These triplet state electrons remain in their excited state of phosphorescence for scores of microseconds (up to about 200 microseconds, or 0.0002 seconds). With such a long lasting state of free electron flow, their ability to be captured is theoretically significantly greater than existing technologies.

And if the research team's current efforts (of using only a few molecules of the hybrid materials suspended in a liquid solution) can be extended into practical real-world scales, then products yielding nearly 100% solar efficiency may soon be achievable.


Solar cell technology

Today's best solar cell technologies utilize several material layers to convert the infrared, ultraviolet and visible portions of the spectrum into electrical energy. This equates to about 61% efficiency in the furthest extremes of the technology, though something around mid-40% is far more typical. Solar cells like these are also incredibly expensive, fragile and impractical for mass production, making them useful for projects like satellites. They have no real potential to become real alternatives for the base consumer's energy needs.

Quite recently, plastic solar cells have been created which achieve between 7% and 11% efficiency. While this may not sound like a lot, such products and materials are extremely inexpensive to produce in bulk quantities, costing about $3 per square meter. The idea of having a rooftop covered by plastic solar cells in place of tar-based shingles has drawn many a consumer's thought since being first reported in 2007. Commercial consumer products based on the technology, which could offer up to 14% efficiency if theories are to be believed, are promised within the next five years.


Alternate forms of using solar power

One of the biggest downfalls of using solar energy on the Earth's surface is that it only works when there is strong sunlight. If it is overcast or if there are clouds, then the resulting efficiency drops sharply and much less power is generated. Also, on most places during most of the year it is dark about 50% of the time. This means some kind of battery storage system must be used to gather the energy during the sun's brilliance in daylight hours, only to then rely on batteries during the night. This adds expense and complexity to solar cell solutions and produces a solution which has peaks and valleys of available power.

Another form of solar power, however, has bypassed some of those limitations. A phenomenal heat absorbing material (made primarily of sodium) uses a relatively simple technology to power itself. By directing the sun's rays through a large array of mirrors which focus the sun's heat and light onto a single spot of the material, it quickly heats up to a few thousand degrees. The material's properties allow it to absorb and store much heat, and then release it slowly over time.

Building technologies around this solution have allowed the sun's direct energy to continue to give off power during darkened times, much like a battery solution but without the need of a battery. The heat is stored in an insulating container, only to be tapped to power steam turbines or some other form of heat-sensitive motor technology.


Still not enough, more to come

The materials these researchers have created is not ready for prime time. Only a few molecules were created through a joint effort of the Ohio State University team and a team of chemists from the National Taiwan University. They synthesized enough of the material to carry out preliminary tests. And while these early findings are truly remarkable, there are still more on the horizon.

Supercomputers are enabling an entire new area of materials. No longer do scientists have to physically create samples of every possible material in the lab, only to test and document everything they find about it. Today they can set up a series of parameters and instruct a supercomputing machine to find the one that best aligns with their desires, wants and wishes. And while such computations often takes many days or even weeks for each trial material, it's more economical and feasible than the old route. Plus, it enables materials like these which were, in this context, accidentally discovered using computers.

The materials analysis these supercomputers carry out is only as good as they are properly designed, and the machine is powerful. Technology sciences like semiconductors and machine manufacturing are quickly overcoming every aspect of limitations regarding the machine's power. And ironically, faster computers are allowing research teams to develop better and more comprehensive models for materials research.

It won't be too long before supercomputers light the way for the truly revolutionary form of renewable energy generation. Who knows, it may come from a bacteria inside the digestive tract of a beetle. But, if you believe anything in science then you must believe it's out there. We just have to find it. And tools like supercomputers, and efforts like these at Ohio State University, are proving time and time again how valuable they are in increasing man's knowledge.
__________________________

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Topic Outline
Subject Author Message Date ID
I hear a version of this story like every three months.
Oct 25th 2008
1
my happy thought for the day
Oct 25th 2008
2
damn... first an asian kid comes close with 3D panels....
Oct 25th 2008
3
and its a shame that all we do with oil is burn it
Oct 26th 2008
4
Well, let's be careful.
Oct 26th 2008
5
      How do you feel about nuclear energy?
Oct 26th 2008
6
           Well of course there's nuclear and there's nuclear.
Oct 26th 2008
7

Triptych
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Sat Oct-25-08 12:24 PM

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1. "I hear a version of this story like every three months."
In response to Reply # 0


  

          

hopefully this one pans out.

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Drizzit
Member since Sep 19th 2002
6467 posts
Sat Oct-25-08 04:25 PM

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2. "my happy thought for the day"
In response to Reply # 0


  

          

thanks.

hopefully it all comes together.

  

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Illadelph Nerd Swagga
Member since Aug 31st 2008
1883 posts
Sat Oct-25-08 06:31 PM

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3. "damn... first an asian kid comes close with 3D panels...."
In response to Reply # 0


  

          

And beforehand a bunch of folks come up with a way to store energy created from solar, wind, or h20. Seriously there's no excuse to rely on oil period. We coming out with fewer excuses to stay on something that'll completely deplete eventually.

------------------------------------------

My president is black, my Linksys router's blue!!!

  

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zewari
Charter member
7113 posts
Sun Oct-26-08 01:35 AM

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4. "and its a shame that all we do with oil is burn it"
In response to Reply # 3


  

          

what a waste of potential

  

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stravinskian
Member since Feb 24th 2003
12698 posts
Sun Oct-26-08 03:03 PM

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5. "Well, let's be careful."
In response to Reply # 3


          


That story about the kid was very misleading. He was involved in some research, but he didn't build anything, or even model anything.

This story actually is real science. The PNAS doesn't publish anything that isn't really important. But it's basic research. We have very little idea of how this material might translate into full-scale devices, and even less about how difficult it would be to produce them.

It's very good news, but we can't get our hopes up. A lot more research still needs to be done before we have any idea if we could turn solar energy into a realistic replacement for fossil fuels. It's possible, but by no means guaranteed.

It's true that we have no excuse for swallowing up so much petroleum. But for now, the only tool that we really have is conservation.

  

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Warp and Woof
Member since Dec 05th 2002
9999 posts
Sun Oct-26-08 09:17 PM

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6. "How do you feel about nuclear energy?"
In response to Reply # 5


          

Because with the limited amount of knowledge that I have on the subject, I feel that it might be the best thing to bridge the gap between fossil fuels and the 'perfect' energy sources like the one mentioned in this article.


I'm #ffffff

  

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stravinskian
Member since Feb 24th 2003
12698 posts
Sun Oct-26-08 09:49 PM

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7. "Well of course there's nuclear and there's nuclear."
In response to Reply # 6


          

In talking about it as a bridge, I assume you're meaning fission energy. And I guess I basically agree with you. It has extremely serious drawbacks, but it's probably a necessary evil. In the US, we're having trouble figuring out a way to deal with the nuclear waste we're producing already; that problem would get substantially more serious if we attempted to increase fission to supplant fossil fuels. Also, as I remember, there is some question about the long-term availability of fissionable uranium. Uranium 235 is pretty rare, and I don't think it's particularly clear that it would last us all that much longer, as a primary energy source, than fossil fuel. That said, it is the one energy source we're aware of by which we could, in principle, supplant a substantial fraction of our petroleum usage. So it deserves to be taken seriously.

The other story, of course, is fusion. I'm a huge believer in fusion. It promises practically limitless energy, with practically negligible waste and no danger of fallout if there were an accident. The problem is, it's much harder to contain a sustained fusion reaction. We have to deal with extremely high-temperature plasmas. And we simply don't understand the physics of these plasmas well enough to know how to sustain them in a reaction, or whether it's even possible. A great deal of fundamental and applied research will be needed to suss this out. So it's obviously not a short-term strategy. If I had to list off the top five fuckups of the US government over the last decade, then the way we've dicked around with funding our commitment to the ITER project,
http://en.wikipedia.org/wiki/ITER ,
would certainly be somewhere on that list. And even more sadly, this can't even be blamed cleanly on George Bush. The latest disgrace came at the hands of my very own party, against the stated wishes of the Bush administration. We, as a country, are really dropping the ball on this.

  

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