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Power Technology

Invisible Solar Nano Cells Promise Clean Energy 88

An anonymous reader writes "ZDNet is reporting that Harvard scientists have developed a silicon nanowire 200 hundred times thinner than a human hair that crank out up to 200 picowatts. Charles Leiber from Harvard University, who devised the technology with colleagues, is quoted: "An individual nanoelectronic device will indeed consume very little power, but to do something interesting will require many interconnected devices and thus the power requirement — even for nanosystems — can be a challenge". Conventional sources, he added, are "bulky, non-renewable and expensive" by comparison."
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Invisible Solar Nano Cells Promise Clean Energy

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  • by Anonymous Coward
    I'd be 95 cents short of a dollar.
    • As they currently exist batteries don't work. I have lived off solar energy for over seven years now. I wrote Exposed; the Solar Energy Con which is available at This is written from a woman's perspective and is an accurate representation of what it is like to live off the utility grid. My point is that if you can read it and still support solar you need your head examined. The country is so focused on solar energy that any one who doesn't support turning the world into a solar array is an
  • by rgaginol ( 950787 ) on Wednesday October 17, 2007 @08:30PM (#21018967)
    what's sad is that this was discovered in the attempt to create a more life like toupe;P
    • Re: (Score:3, Funny)

      The really sad thing was it they didn't discover it in the 70s. A self powered neon toupe would have been huge among the middle aged disco fans.
  • Localizers (Score:4, Interesting)

    by 56 ( 527333 ) on Wednesday October 17, 2007 @08:31PM (#21018987)
    Anyone ever read Vernor Vinge's 'A Deepness in the Sky'? These things might be a great power source for the localizers he mentions.
    • Anyone ever read Vernor Vinge's 'A Deepness in the Sky'?

      Nope. I tend to avoid books by illiterates who need five words to say "height" ;)

  • The Danes call them "Magical Elves".

    Same theory pretty much. Let me know when they're around again because I need some cookies from those fuckers in the goddamn tree.
  • by Linker3000 ( 626634 ) on Wednesday October 17, 2007 @08:33PM (#21019007) Journal
    "...Charles Leiber and colleagues at Harvard University, have devised a 'silicon nanowire' that can convert light into electrical energy.... ...Two hundred billionths of a watt may not seem much, but at nanoscale it is enough to provide a steady output of electricity to run ultralow power electronics, including some that could be worn on -- or even inside -- the body. "

    Erm, how bright is the inside of a body!?
    • Re: (Score:1, Funny)

      by Anonymous Coward
      "Erm, how bright is the inside of a body!?"

      I don't know about you, but the sun shines out of MY ass.
    • Should be plenty of light inside the body, if you count infrared, and not all tissues are completely opaque. Should be some parts of the aqueous humour of the eye that aren't used for imaging, too.

      Gaah where's my fork (--recent eye surgery patient)

      • The Phrase "where the sun don't shine" applies to Goatse as well. Even more so, since the sun will be to affraid to shine and hide itself behind a cloud should it ever be brought face to orifice with Goatse.
    • Re: (Score:3, Funny)

      by vbraga ( 228124 )
      It depends on the type of body. Think of goatse. Sunshine can reach inside it. Well, almost the whole Sun.

      (Yes, I'm ashamed of thinking this...)
    • Re: (Score:3, Funny)

      Erm, how bright is the inside of a body!?

      It's being developed for people that live near Chernobyl. Kind of like the X Ray film that you just have to stand next to for five minutes and the lead lined shorts that are a fashionable item in Kiev.

    • Re: (Score:3, Funny)

      by fishthegeek ( 943099 )
      That depends. From my point of view there aren't any problems with light getting to the inside of a body.

      Hannibal Lecter
    • Outside a dog, a book is a man's best friend. Inside a dog, you need carbon nanowires to read.
    • Re: (Score:3, Insightful)

      Actually it's moderately transparent - unless you happen to be one of the subset of humanity that has a particularly dark skin pigment. (Even then it's pretty transparent except on the outer layer - not that it matters. B-( )

      Hold your hand up to a lamp. Notice the light coming through it. Very diffused, but clearly quite a bit there.

      Of course if you move the nanowires out to the skin level the transparency of the body - even with a heavily-pigmented skin - is no longer an issue.

      However, given the enorm
  • by MBCook ( 132727 ) <> on Wednesday October 17, 2007 @08:46PM (#21019149) Homepage

    Virtually invisible to the naked eye, a single strand can crank out up to 200 picowatts.

    I hate science reporting. It's also nice to know the editors aren't doing their jobs (ZDNet, I don't blame /.). What is a single strand? Is that 10mm long? 10cm? 1m? There is a big difference between those three. The summary just chops that sentence up worse. And why do they always use human hair as a comparison? Who's hair is that? Some people have very thin hair. For some people it is quite a bit thicker. If you are comparing it to the average, you should include that word. Also are we talking theoretical maximum or a practical estimation under normal daylight conditions?

    It's great to know this generates 200 picowatts per something. How about comparing it to a normal production solar cell. I'm glad you can make it thin, but it must need some kind of support structure to survive, so how much thicker does it need to be so it is actually useful? After all, the silicon part of a solar cell is just a fraction of it's thickness.

    • If you are comparing it to the average, you should include that word.
      No, they shouldn't.

      In the case where a reasonable person would understand that "average" is meant, then "average" is just a useless word cluttering up the sentence. Its presence or omission is best left to the writer, subject to the needs of the surrounding text and the work as a whole.

      • You're forgetting that this is "/." and is populated with Geeks... and a few way-out-there Geeks.

        These way-out-there Geeky-Geeks often have a hard rationalizing value comparisons that the closer to average type Geeks might consider common sense.
    • by sumdumass ( 711423 ) on Wednesday October 17, 2007 @09:33PM (#21019573) Journal
      Well, I too would like to know more about it. Like can it be woven into a yarn or thread and made into clothing? A 200 pico watts isn't much power but if it is 1 strand 10 centimeters long and something like 10 strands can be spun/woven into a single thread similar to wool and cotton that can be used to weave and overcoat, how much power would that be? Could it be possible to make cover for your hybrid electric car or even a soft top that is also a solar charger so the batteries are at full charge sitting in the parking lot waiting for you to get off work. Even a ball cap that can power your Ipod or Walkman would be great.

      I mean the possibilities are endless depending on the properties of the stuff. It is made out is silicon it is small, and it produces power. It should be Usable in a lot of ways.
      • I'm guessing it could be made into a larger fiber, but I don't think it would make any sense to do so.

        Since this is solar power, any of the nano-fibers that are inside the larger fiber wouldn't generate any power since they wouldn't receive any light. Also, I'm guessing that there would be problems "lining up" the different layers of the nano-fibers resulting in some sort of short in the system. Another question I have is, dealing with this small scale, does the internal resistance in the wire cause scal

    • by Falstius ( 963333 ) on Wednesday October 17, 2007 @09:35PM (#21019591)
      As someone who teaches MEMs technology, I find myself frequently using the human hair comparison with new students. It is the closet thing to a microstructure that people have daily physical experience with, and helps give a feeling of scale. A 200 micron wide bridge is an abstract number until you understand it is about 1 to 4 hair-widths (depending on whose hair). Its not nearly as meaningless of a unit as LOCs (Libraries of Congress). If you have a better suggestion for a comparison, I'd love to hear it.

      Your point about leaving off the length is a good one. Science journalists don't seem to understand enough about what they're covering to know which points are important or which claims are plausible.

      • by salec ( 791463 )

        If you have a better suggestion for a comparison, I'd love to hear it.
        Width of spider silk thread? It seems to be rather uniform (or perhaps it is just too thin to tell).
        • Width of spider silk thread? It seems to be rather uniform (or perhaps it is just too thin to tell).
          Which strand? The anchor strands one can clearly see or the capture strands? Which species of spider? And of course, I live in an area where the only spiders are taratulas you insensitive clod!
          • by salec ( 791463 )

            Which strand? The anchor strands one can clearly see or the capture strands? Which species of spider? And of course, I live in an area where the only spiders are taratulas you insensitive clod!

            I see... the nature doesn't provide enough precision (or nothing at all). Then I propose strands of industrial artificial material(such as, i.e, lycra, used for ladies stockings) assorted by their width. You can have samples made into microscope slides (you can have free strands too), students can see them through wi

            • If I wanted to show them precision widths under a microscope, I could show them .... I know, MEMS!

              Most MEMS have features that are visible to the naked eye, if not easy to identify. The point is not to have an accurate unit of measure (we have tools for that) but to give a sense of scale that students can easily internalize. The same is true in science reporting, precision is not necessary so long as the analogy gives a reasonable feel for the scale.
              So specifying something in hair widths is okay (va
      • Where I live, we have a nice little measure of length that is millimeter; 200 micron is a fifth of a millimeter, easy to visualize, not all that abstract. On the other hand, 1/200 of a hair-width is an abstract number, it's probably practically just as invisible as 1/20 or 1/2000 of a hairwidth. If it's invisible, it's abstract, and there's little that can be done about it. So I don't quite see hair width as a useful measure.
    • In other words, we need a car analogy.
    • by fractoid ( 1076465 ) on Wednesday October 17, 2007 @11:51PM (#21020737) Homepage
      The article also contains this gem:

      Incoming light generates electrons in the outer shell, which are then swept into the second layer and the inner core along micropores.
      Nice to see that they're actually generating electrons instead of just moving them around like most of those lazy-ass photovoltaics. I hope they generate positrons at the same time to balance out the overall charge of the universe...
    • How many of these can fit in the Library of Congress?
    • Well the Human Hair Anology is just so a person has some basic reference for small things. Giving exact size for the general audence is a waist, if you are more interested read the sciencetific papers. 200 times the size of a human hair even if they have corse hair is still unobservably small. Small enough to be wove into fabric without feeling it (like wires) or placed in the body without feeling it. Some Bacteria could use it as swords to fight of other bactera.
  • I wonder (Score:5, Interesting)

    by Dr. Eggman ( 932300 ) on Wednesday October 17, 2007 @08:47PM (#21019157)
    Any biologists out there who wishes to inform me of how this solar cell compares in efficiency and equivalent energy production for photosynthesis. I understand that they're are two very different forms of energy (storage medium may be a better comparison) but I would be interested as I have thought that perhaps natural evolution had already long ago derived the most efficient ways of recovering energy to drive its organisms. I wonder if the real future of small scale generators/batteries lies with organic synthesis of energy through genetically modified organism with some medium transforming the resulting chemical energy into electrical energy (not unlike a battery but with it's own complications necessary for dealing in the organic compounds) rather than straight up developing life-facsimiles.

    Then again maybe I'm just rambling on after approaching the 40th consecutive waking hour... It'd be nice to know.
    • Dr. Eggman asked: Any biologists out there who wishes to inform me of how this solar cell compares in efficiency and equivalent energy production for photosynthesis?

      I'm a photovoltaics expert, not a biologist, but I can answer that question. The answer is, they don't quote any efficiency numbers.

      That's usually a suspicious sign.

      • 1)what is your take on the magic PV cleaning on the rovers, especially some get cleaned, some don't. Is it all dust devil cleaning, or is there perhaps some other static situation going on?

        2)what do you think of the thin film printed PV that is hitting the market now or "real soon"? Any bets or SWAGS on which company has a realistic and decent product? I realize you most likely work with very high end, maximum watts per sq. meter, wheras on ye olde earth, watts per dollar is probably more of a practical bus
        • Well, from what we know there ought to be some electrostatic effects going on... but all the clearing events we've seen so far look like they've been wind events. (Not necessarily dust devils-- some of the clearing events have occurred at night. And we see them on Opportunity, where we haven't seen actual dust devils.) Many of the images--e.g., this one [] show clear wind tails on the shadow post of the cal target and elsewhere. For terrestrial use, thin-film PV has to be both cheap and also durable-- the
    • Re:I wonder (Score:5, Interesting)

      by StikyPad ( 445176 ) on Wednesday October 17, 2007 @10:48PM (#21020201) Homepage
      I have thought that perhaps natural evolution had already long ago derived the most efficient ways of recovering energy to drive its organisms.

      Not usually true. Plants and animals have plenty of other concerns, such as the efficient storage thereof, combating predators, reproducing, etc., any one of which could take precedence over obtaining energy. Is fat the most economical storage medium? It's pretty good, but other factors come into play: it's not toxic to the body, it's pliable, which permits relatively free movement, it's a good insulator, and it provides protection to bones and internal organs (any of which may or may not be an evolutionary side effect). Natural selection is about favoring the most competitive in a particular environment, and obtaining the most energy, while ignoring other factors, is not always the best strategy. A design that extracts more energy from sunlight than pine needles might be more prone to wind damage, pests, molds, fungus, etc. Even if an organism is more efficient at extracting energy than its competitors, that's no guarantee that its the *most* efficient possible design, just that it was good enough.

      Additionally, what we're primarily concerned with is electromagnetic energy. There are always losses in any conversion, and if we convert the sunlight into chemical energy, then back into electromagnetic energy, we're guaranteeing more losses than if we can harness/store the sunlight directly. That's why it's often more efficient to use net metering rather than off-grid battery storage alone. Many people opt to include batteries in their solar systems, but that's typically for the purpose of grid independence and/or backup power. Of course there are losses inherent in converting DC to AC, so that must be considered as well. Overall, the more directly you can transfer the power from the source to the load, the more efficient that transition will be.

      I'm not a biologist, but I did stay at a Holiday Inn last night.
      • "I have thought that perhaps natural evolution had already long ago derived the most efficient ways of recovering energy to drive its organisms."

        Nope. Photosynthesis typically runs at about 1-2% energy conversion efficiency; the best plants ever are about 4%. The best solar cells are now hitting 40%.

        On the other hand, photosynthesis isn't just about energy conversion-- plants also synthesize sugars.

    • Re: (Score:3, Interesting)

      I had a graduate professor (in bioengineering/nanotechnology) who claimed that the light absorptive complexes in plant cells (chloroplasts) were on the order of 95% efficient(I've forgotten the exact number) in certain wavelengths. (not green since that all gets reflected for you to see the nice green color of the leaf)

      Unfortunately comparing the efficiency of plants to this wire thing isn't that simple. Chloroplasts have lots of internal complexes(Thylakoid disks) full of organized protein structures th
  • Where is the promise that this will be commercialized in a few years and we can paint our houses with it? What kind of solar article is this?
    • Yeah, will we have it on the shelves powering a ridiculous product that nobody wants in 5 years or not?

      I want my ridiculously glowing nano-wire powered useless product!
    • Oh, come on! Give it some credit! In the title of the submission *alone* there are three terms that throw up a red flag:

      -invisible solar cell (Yeah, light ignores it, but is also absorbed by it.)
      -clean energy

      (Btw just got back from a /. anniversary party. Fun stuff.)

  • We all want to look for macro-applications right away, but it seems pretty obvious that this is meant for the micro.

    I'm not going to stoop to doing the math (*ahem*), but I'm imagining we're not talking about a huge efficiency gain over high-end conventional sources.

    Not to mention the "assembly barrier" to something like this. You though installing that modchip to put Fedora on your XBox was hard, that was just a few fiddly wires. Imagine some poor Chinese factory slave-labor dude with his soldering iron an
    • Good thing those chinese got small hands. And I think it serves them right for making the compact car that requires small hands and fingers to work on anything. Oh wait, that's the Japaneses. Or am I just confusing all my ethnic stereotypes?

      Anyways, this is one job that I wouldn't complain if a robot took from us.
  • Hey.... (Score:5, Funny)

    by DoofusOfDeath ( 636671 ) on Wednesday October 17, 2007 @09:22PM (#21019485)
    "Invisible" "Solar" "Nano" "Cells" ... "Clean Energy"

  • I think this article was meant for Dora the Explorer club, and not /.

    The journalist is either completely clueless or trying to make it comprehensible for kindergarten. The result is so wrong and incomprehensible that it is worthless: ...The cable itself looks, like the cables used to hook up cable television networks...But the similarity stops there...Incoming light generates electrons in the outer shell, which are then swept into the second layer and the inner core along micropores. These "holes", as they
  • by Nullav ( 1053766 ) <moc@CURIEliamg.valluN minus physicist> on Wednesday October 17, 2007 @09:53PM (#21019745)
    Curious, does that mean 20,000, or is it just redundant moonspeak? I've heard people say things like 'a thousand million', but never for such small numbers.
    • Of course outside the US a billion is one million million (bi-million). Thats why people say one thousand million - because it's completely different.
      • I don't see what the sexual orientation of numbers has to do with anything
      • Of course in Europe a billion is one million million (bi-million). Thats why people say one thousand million - because it's completely different.

        Fixed that for you. The "US" usage of billion is more common worldwide, and increasingly more so. It keeps us all from having to deviate from the systematic approach. A trillion isn't a million million million, is it?

        It gets really confusing when you're talking in powers of higher than that. A novemdecillion, for instance, is easy to calculate - that's nove - 9, dec-10, so 19 groups of "000" after the first. The formula for understanding the number is more complex under the french system, which is why

        • Yes, using the British/French/German... system a trillion is a million million million, or 1 000 000^3. I'm in Australia and we seem to use both notations.

          In the US, a novemdecillion is 10^60, or 20 groups of '000' (19 after the first). In long scale a novemdecillion is 1 000 000^19. No harder to calculate, just completely different. My preference is for the latter simply because I am familiar with it.

          The truth is that the US system is commonly used in many english speaking countries due largely to the Amer
    • by caluml ( 551744 )

      'a thousand million'
      It's because in the UK, a billion was (is still?) a million million, although it's pretty much taken as standard now as a 1000 million. I assume they wanted to avoid confusion.
  • If it's a solar cell doesn't it have to absorb some wavelength of electromagnetic radiation?

    Then it isn't invisible, is it?
    • I'd presume they're saying it's invisible due to its size, not its transparency. Make a sizable array of them and I guess they'd be a similar colour to other solar cells.
  • Two hundred whole picowatts?!!
    • Yes, isn't it amazing? 0.2 entire nanowatts! You'd only need about 5 billion of them to provide you with a single useful watt.

      Actually, when you come to think of it that's pretty good for such a nanostructure. But I wonder if stringing such structures together in a scale that would permit reasonably measurable current flow wouldn't generate enough heat to let the magic smoke out at ambient STP? Is there a point of diminishing returns, or could they perhaps be partially embedded in a matrix of something th

  • A picowatt is a unit of power equal to 10^-12 watts, or one-millionth of a microwatt. That's a lot of zeros and a really tiny number.

    Lets do some questimating! An average hair is around 50 micrometers thick, so lets guess they are talking about a 0.25 micrometer thick wire. Lets guess they are talking about a 10 cm long piece. Plugging the numbers and their stated power yields a whopping 0.008 watts/squaremeter. A cheap 6% efficient solar cell in bright sunlight (1 sol = 1000watts/sqmeter) gives you 60
    • Re: (Score:3, Interesting)

      by marcosdumay ( 620877 )

      1 pico watt is still 1.6e8 eV/s. See, a huge number. A hypotetical nano-assembly powered by that could ionize near 6.5e7 hydrogen atoms per second, and, while 250nm is a bit big for such application, you could still put 4e6 such machines in a centimeter, leading to 26e13 atoms/(s cm).

      Of course, everything depends on how long is the cell. You got 10cm from nowhere, it would even be hard to make it that long. If you are right about the length, it is useless. But if its length is 4 times bigger than the width

  • Would someone do the:

    "I for one, welcome my invisible solar nano cell overlords" bit.
    I miss it.....
  • Problem is, they're not green.
  • You mean future AI's won't place me in a jar and hook me up to the Matrix to farm me for electricity? WTF? Are you saying that was like 'science fiction' or something?

  • Let's see, we've got nanowire that's "Thinner than a human hair", and generates 200 picowatts of electricity. So, if we use these things tethered at one end and free to sway loose at the other, we have a mat of electric-generating "fur". Fuzzy satellites? Implant into the human scalp (To cover those bald spots) and you could power your cybernetic implants. Self-powering Electro-Luminescent wire (Charges when off)?

    Weave these things into a cloth, and we could have spaceships with a power-generating solar sa

  • Let's do a little math. 200 picowatts. At 1 volt, that's 200 picoamps. So you can drive a circuit with a resistance of ( R=E/I), wait for it--- 5,000 megohms. That's about 100,000 times a typical circuit resistance. I'm not saying it can't be done, but it's going to be mighty tricky to design a useful circuit at those power levels. Even more challenging-- eventually the circuit has to drive some interface, be it a USB port, a LED, or a buzzer, and those require millions of times more power than
    • Even worse, it's more likely to be something like a microamp at 200 microvolts. Sure, that might only have to drive into 200 ohms, but still...
  • You can bet the good ol' developers of the Land Warrior [] will be keeping an eye on this. The concept of the Land Warrior in it's current form sucks, as pointed out by numerous posts, but one of the major downfalls (aside from the ironic decrease in situational awareness) is humping around 30 pounds of batteries... Of course, the suit would only be good in the day time if they used this, but hey, that is their problem to figure out!
  • is all over the place. First they talk about a solar cell. Then they talk about implantation. Someone should tell the journalist that ther is very little sunlight inside our bodies. I think they are talking about a new type of nanocell (tube?). However, that nfo was lost in all of the vague applications. The journalist should have reported on the difference b/w this nano-cell and other related research such as [carbon] nanotubes. These cell are compsed of 3 layers. What are the layers? Are all 3 layers Si?
  • hybrid solar that was built in Pulau Kapas is not only the first in Malaysia but also the first in SouthEast Asia...
  • With DHCP pools you often end up with multiple people making edits from the same IP. This means that you can't really consider an anoymous editor to be one person. FWIW, it can be interesting to look at the edits previously made by my co-workers on my work IP address.
    • Well, to be pedantic, you'd need either NAT or an HTTP proxy. DHCP might be used to assign the off-network addresses to the machines behind that single routeable IP, but that's not necessary.
  • well ofcourse with my invissible dollars..
    Or Euro's you wont see the difference

    And since it's also nano you wont even feel it it's thinner the a hair and smaller then pencil point...


"Laugh while you can, monkey-boy." -- Dr. Emilio Lizardo