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Science Technology

Carbon Nanotube Towers Could Increase Solar Power 141

Posted by Zonk from the tiny-towers-of-power dept.
Vict0r writes "Researchers at the Georgia Tech Research Institute have recently demonstrated a way to grow carbon nanotubes in towers. The article also discusses applications for solar cells." From the article: "Reflections off the Gothamesque towers would provide more opportunity for each photon of sunlight to interact with the p/n junction of the cell. That would increase the power output from PV cells of a given size, or allow cells to be made smaller while producing the same amount of power."
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Carbon Nanotube Towers Could Increase Solar Power More

Carbon Nanotube Towers Could Increase Solar Power

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  • Even better (Score:5, Funny)

    by nizo ( 81281 ) * on Tuesday March 01, 2005 @07:21PM (#11817921) Homepage Journal
    Reflections off the Gothamesque towers would provide more opportunity for each photon of sunlight to interact with the p/n junction of the cell.

    We need mirrored solar cells. Just set them up so they reflect the light back and forth between all the cells for a neverending unlimited source of energy!

    • Re:Even better (Score:2, Informative)

      by Game_Ender ( 815505 )
      That would be cool if only that pesky photo din't get absorbed ;)

    • Re:Even better (Score:5, Funny)

      by PitaBred ( 632671 ) <slashdot&pitabred,dyndns,org> on Tuesday March 01, 2005 @07:23PM (#11817943) Homepage
      "In this house, we obey the laws of thermodynamics!" - Homer S.
    • Obviously, you'd have some energy loss.... but mostly, why wouldn't this work? I'm not scientist or electrical engineer, but I would think you could point a light beam from the sun using mirrors into a chamber full of mirrors and that also had solar panels in it.........

      • Re:Even better (Score:4, Informative)

        by Umbral Blot ( 737704 ) on Tuesday March 01, 2005 @07:26PM (#11817989) Homepage
        Because solar panels take energy from the light to produce electricity. You can only extract so much energy from a given photon.
      • Once the light comes in contact with the solar panel, the light is absorbed. Why rish wasting energy reflecting it when you can just absorb it on first contact?
        • Because you can't absorb it all at once. Check how eyes [hhmi.org] try to catch as many of the fotons flying around as they can. For the same reason chlorophyl in plants has an 'antenna complex [langara.bc.ca]'.

          Bad luck you cannot patent this idea as it is already in use, see for instance this paragrpah on reflection [energy.gov] , describing such an efficiency increasing trick.
          • very true, but the nanotube structure takes care of absorbing the reflected photons... putting in mirrors will just provide a useless surface that won't be able to absorb energy.

      • Re:Even better (Score:5, Informative)

        by Issue9mm ( 97360 ) on Tuesday March 01, 2005 @07:28PM (#11818004)
        Because, as is the point, the solar panels ABSORB the light, not reflect it back. I don't have any hard numbers, but as PV cells are designed specifically to absorb sunlight, let's assume they do this pretty well. While some (let's say 20%) of a ray of sunlight is reflected back into the chamber, it would surely be caught by the next PV cell and absorbed wholly (unless, possibly, that PV cell is already working at maximum absorption, which, if is the case, negates the point of bothering to reflect in the first place.)

        -9mm-
      • Well, the photoelectric effect is the process in which the energy of a photon causes an electron to jump off of its parent atom. Do this a bunch of times and you have a current. Once a photon is "converted" in this sense, it no longer exists as a photon, and as such you can't complete the procedure a second time. Perhaps such a process might be able to increase the efficiency by capturing the light that was not utilized by the solar cell (since techincally any light that gets reflected off of them is a l
        • Mirrors have a cost, to use a mirror to reflect the nominal light reflected off of a solar cell back into the solar cell would never be as cost effective as using the same mirror to reflect the much higher energy of direct sunlight onto the cell.

          At some point the additional cost of higher effeciency isn't the best use of materials.

          30% effeciency is a workable number - and the cost of energy isn't affected as much by doubling this number as it is by other concerns, such as tracking the sun, storing the ene
      • Because evil gnomes will sneak in when you're not looking and hold their hands between the mirrors to block the light and foil your plans, obviously.

    • Make solar cells like leaves not like guts ! (Score:5, Interesting)

      by mishmash ( 585101 ) on Tuesday March 01, 2005 @08:02PM (#11818337) Homepage
      No. If surface area mattered then leaves (nature's way of capturing solar energy) would have folds and protrusions like the gut does to increase surface area. What leaves do is make sure that some of the light gets through to the next layer. This happens both in an individual leaf - light is not caught just at the top surface but all the way through the leaf. Also a leaves don't trap all the available light, some is left for leaves below - it's totally dark walking through a forest. Make the solar cells more transparant - thats the way to get the effect of increased surface area the article referes to.

  • Small problem (Score:5, Funny)

    by winstonmeister ( 863683 ) on Tuesday March 01, 2005 @07:23PM (#11817944)
    "Reflections off the
    Gothamesque towers would provide more opportunity for each photon of sunlight to interact with the p/n junction of the cell.
    Unfortunately, Batman tends to work at night, so solar cells won't be of too much help.
    • Unfortunately, Batman tends to work at night, so solar cells won't be of too much help.

      Have you ever seen the Batsignal [google.com]? Uses a lot of much needed power. If Gotham doesn't use solar power for that they'll soon need Captain Planet's help instead.

      • I mean storing solar energy from the day into a battery for the nighttime signal. Hopefully you could have guessed that, and not that a night light would be powered by a sun that's not "shining."
    • Maybe they could convert the batmobile to hydrogen, and use the solar for disassociation of water. Personally, I'd like to see this made into a portable nitrous oxide manufacturing machine. It could at least provide the power, and everything you need is present in air if you can figure out a way to separate out nitrogen, too. :)
    • I've got this solar powered flashlight lying about somewhere. Never found good use for it, but maybe Batman is interested.

  • Obvious geekthink (Score:1, Informative)

    by Anonymous Coward
    Even though this has only been used to generate towers that are microscopic in size, let the "and I bet this can be applied to beanstalks!" threads start in 3...2..1....

    • double insulated towers (Score:1, Interesting)

      by Anonymous Coward
      A simple and donated to the non-patentable public domain by me solution is:

      a. get double paned glass windows
      b. install on 100 story office tower
      c. channel the air from inside of one window to the one above it (chaining them until top of building)
      d. put wind turbines at top of building

  • But what could you do... (Score:5, Funny)

    by Fitzghon ( 578350 ) on Tuesday March 01, 2005 @07:24PM (#11817958)
    ... with a Beowulf cluster of these things?

    Fitzghon
    • Maybe we can power a Beowulf cluster of toaster--er, computers. Or microw--I mean, cars--dammit, GTRI, you and your confusing waffle-looking wafers! But I love'em; we should make a worldwide solar-collecting mesh covering Earth with these wafers, so anyone who needs "clean" energy can have it--using, of course, some sort of redundancy to prevent something like the 2003 Northeast Blackout. How would that go?
    • Imagine a farm of these! You could power a Beowulf cluster!

      -DrkShadow

  • Carbon Nanotubes....in towers? (Score:4, Interesting)

    by eddiegee ( 236525 ) on Tuesday March 01, 2005 @07:24PM (#11817962)
    So where's my Space Elevator?
    • I was wondering whether or not you could use this technology to grow cables for a space elevator. If you could get a spiral form going, it might be able to spew out cable (okay, it would probably be too slow to be called "spew") pre-formed.

      • Re:Carbon Nanotubes....in towers? (Score:5, Interesting)

        by Rei ( 128717 ) on Tuesday March 01, 2005 @07:51PM (#11818194) Homepage
        No. The problem with tubes this small is that there is insufficient van der waals force holding them together; the tubes are strong, but the force keeping them as a single bundle isn't. And probably won't be unless we can produce quite large tubes. One alternative is that, under high pressures, nanotubes interlink and trade their strong sp2 bonds (graphite) for weaker, but still quite strong sp3 bonds (diamond) between tubes. In theory, these interlinked ropes (not really nanotubes, but a new material) should be quite producable once regular vdw-bonded nanotube ropes without any sort of binder in them become producable and affordable.

        There's another problem with space elevators, though: not only would interlinked tubes prove somewhat weaker than non-interlinked tubes in all likelyhood, but non-interlinked SWNTs proved rather weak in direct tensile strength tests. One test that I read about had a maximum strength of just over 60GPa, instead of the >100 typically called for to produce a reasonable space elevator on Earth. Now there are many different types of SWNTs depending on how the graphite is rolled up, so they could vary, but signs don't look good.
        • Also, the cost of production of CNTs is still rather high, a CNT space elevator many, many kilometers long is probably still to expensive for government to be interested (since they'll probably be the ones to fund it).

          However, Double Walled Nanotubes [nanotechweb.org] have some interesting properties that might be able to surpass the listed "short" comings of SWNT, specifically the thermal and chemical properties.

          I hope this isn't considered nested posting or something like that.

          • Unfortunately, that won't work - these will be denser. The two critical factors for keeping the distance-to-width-doubling low for a space elevator: material density and tensile strength. Lets say that these are twice as dense. If the tensile strength is the same but the density is doubled, the distance between width-doublings of the cable is halved, which means that the cable has to double in width twice as many times, which is generally a completely unacceptable situation.

            Still, they're interesting :)
        • It's not just van der Waals holding nanotubes in bundles together; it's also pi-pi stacking. And let me tell you, those bundles are pretty tough to exfoliate, at least from a chemical standpoint.
          • And let me tell you, those bundles are pretty tough to exfoliate, at least from a chemical standpoing

            Unfortunately, not from a tensile strength standpoint. The strongest nanotube rope strengths I've read about simply used nanotubes in a binder, and were about as strong as kevlar. Pure nanotube ropes tended to be under 1GPa, if I'm remembering the articles I've read correctly.

  • Slightly OT (Score:4, Interesting)

    by frankthechicken ( 607647 ) on Tuesday March 01, 2005 @07:24PM (#11817963) Journal
    For soldiers operating in the field, especially in desert areas that receive lots of sunlight, the new "solar tube" cells could provide an alternate power source for the growing number of electronic devices they use

    Given the amount of energy this "growing number of electronic devices" probably puts out, doesn't it make the slodiers easier to spot due to the energy signatures they are putting out? If so, doesn't it slightly impact on the actual usefulness of the electronic devices?

    I'm guessing this is factored in, but how much shielding is possible, and how far would the new "solar tube" be able to be shield it's energy signature from the enemy?
    • I doubt the enemy will be carrying tricorders with them to pick up the energy signal. They'll probably be using eyes just like the other soldiers.
    • While it COULD be possible to detect solidlers using similar technology, it would still be VERY difficult.

      #1 as you stated most of the electronics are probably well shielded so as no to put out much radiation.

      #2 a single soldier or even a squad is a very small target from any distance and if you are close enough to really zero in then you just use your eyes.

      #3 By it's very nature a photovoltaic cell will NOT put out radiation. It is built to absorb radiation, not put it out! Radio waves are produced by
    • You mean, unlike the energy signal of the fricken humvee they're riding in? I suspect the soldiers doing covert ops on foot don't carry as many gadgets, and probably keep what they do carry turned off most of the time. Anybody else is putting out a huge infrared, sound, and electromagnetic signature from their vehicle anyway...
    • That depends, how do you 'spot' the energy signature of a Magellan Meridian Platinum Mapping handheld? (A very nice GPS unit that has seen action in Iraq). The other big item would be personal cell phones. Anything else is probably supplied by the military and will be shielded (sat phones, laser finders, etc) so it's not that big of a deal.

      I was the idjut during desert storm that had to repair most types of the electronics and crypto units used in the field and never ran into a problem with anyone 'spott

    • Re:Slightly OT (Score:5, Interesting)

      by Rei ( 128717 ) on Tuesday March 01, 2005 @08:00PM (#11818300) Homepage
      I'd actually been thinking about that. For example, picture the speaker on a communications device. Speakers give off a lot of EMF (they're effectively a big fluctuating electromagnet pulling on a diaphragm) - even shielded ones are generally pretty easy to detect and tell what sound was coming from the speaker. CRT monitors (not that common on portables) pump out lots of EMF, too (run "Tempest for Eliza" some time - you don't even need a sensitive directional antenna to listen in). I've read about keyboards have been tempested from over 50 feet away.

      What good is an encrypted signal when the people that you're hunting in a city have a good parabolic antenna pointed at you through a wall that they're hiding behind and are listening to the signal from your radio? Heck, they don't even need to know what you're saying, just that you're there.

      Of course, pretty much everything about warfare would be a heck of a lot harder if the US actually fought a *real* enemy instead of collapsing third-world nations armed with reject Soviet equipment from the 1950s and 1960s.
      • What good is an encrypted signal when the people that you're hunting in a city have a good parabolic antenna pointed at you through a wall that they're hiding behind and are listening to the signal from your radio? Heck, they don't even need to know what you're saying, just that you're there. Answer: you don't get that close. Even in the "close in" fighting of a city, chances of being 50 feet from someone is really, really slim. Unless they're moving very fast, in which case you'd have other problems.
        • I have be told numerous times, and I won't stand by it (nor do I know where the source is) that in the first Gulf War no more than 10% of the percision guided missiles ever hit their target. I'm assuming that smart bombs haven't improved that much since that point. Perhaps that means a single us aircraft can expect to get multiple kills every time out, but they aren't legit (under the Geneva convention ;) ). Err. I'z iz takin us farther in to OT territory.. :) couldn't resist, Mike
      • You mention two things - spying via EMF and sound.

        Trying to pick up a speaker's EMF will be quite difficult because a 1kHz electromagnetic oscillation will have a wavelength of about 300 km! Try making a stealth quarter-wave antenna with that frequency. Of course you can inefficiently pick up signals with non-matched antennas, but I don't know how efficiently you can do this for such a huge wavelength mismatch.

        You mention CRT scanners (I remember reading about such raster scanners awhile back), but th

      • Someone needs to explain to me how Iraq was a collapsing third world nation before the US invaded. Sure they were controlled by a slightly sadistic dictator, but sitting on the bed of oil that they do, they could hardly be considered third world.

        I won't even get in the point where, in all honesty, how else do expect you expect these nations to fight the 'world's greatest military machine'.
    • For soldiers operating in the field, especially in desert areas that receive lots of sunlight, the new "solar tube" cells could provide an alternate power source for the growing number of electronic devices they use

      Woah, let's back it up a bit here - if we have a more efficient form of generating electricity, we will reduce the cost of producing hydrogen which will make it cheaper and more viable to move to a hydrogen economy so we won't need all these soldiers in desert countries protecting the oil^h^h^h
    • I'm guessing it's factored in, but honestly, soldiers put out kilocalories of EM in the infrared range already; it's called BODY HEAT. The few additional watts from electronic devices are probably not going to make that big of a difference, unless you're a pathfinder or something...
  • You might say they were grown in ivory towers, even.

    Ar ar, sorry couldn't resist.

  • But not word... (Score:5, Interesting)

    by davecrusoe ( 861547 ) on Tuesday March 01, 2005 @07:27PM (#11817996) Homepage
    "For soldiers operating in the field, especially in desert areas that receive lots of sunlight, the new "solar tube" cells could provide an alternate power source for the growing number of electronic devices they use. Without the need for trucking in fuel, compact PV cells could directly power certain applications or be used to recharge batteries in soldiers' equipment..." But, no word about innovative residential or consumer uses for the material? What about powering mobile computing systems for rural schools in India, or for use in purifying water in Africa? Sigh.
    • Military applications drive innovation. The consumer applications of the technology are coming.

      • Re:But no word... (Score:1, Insightful)

        by davecrusoe ( 861547 )
        But that's only because we emphasize military spending, and military might. Personally, I'm of the belief that education and educational applications - such as invention, or innovative teaching and learning - in addition to practical humanitarian applications should drive technological innovation.

        If we maintain the mindset that military applications drive innovation, then that's all we'll receive. On the other hand, if we start applying for grants, and applying our funding in new directions, it's forseea
        • If we maintain the mindset that military applications drive innovation, then that's all we'll receive.
          The military is just the ultimate "early adopter" of technology. The underlying research and science is driven by educational institutions.
          One of the reasons the military is such a driving force in innovation is because, like the space program, they are constantly trying to solve problems at the "extremes". Questions like "what if half the country was nuked" was one of the main reasons for the decentra
          • One of the reasons the military is such a driving force in innovation is because, like the space program, they are constantly trying to solve problems at the "extremes".

            Another is that they have lots of money. I imagine if we funded the department of education the way we funded the military, we might have all sorts of research grants for building new education tools.
            • I imagine if we funded the department of education the way we funded the military, we might have all sorts of research grants for building new education tools.
              I doubt it, while the problems for military applications are complicated, they are easy to identify. While I agree schools are under funded, what exactly innovative would you get with $40 billion more in education? Building more schools and hiring more teachers is not innovative. If you're thinking giving more money to universities to do research

        • Personally, I'm of the belief that education and educational applications - such as invention, or innovative teaching and learning - in addition to practical humanitarian applications should drive technological innovation.

          Um, is this technology not being research by Georgia Tech? Granted, they are seeking military funding, but does that make their invention somehow more evil?

          If they military wanted to fund research into the production of highly nutritious high-caloric food for cheap, would you be again

      • That's because the military contractors have control of hundreds of billions in unaccountable budgets. So we have to wait while their braindrain sucks up the innovators, then maybe kills a lot of people so they can't keep it secret anymore, then we can get started on consumer apps. That's pretty wasteful.
    • You should start up a company that does just that!

      Imagine the great things you could bring about in the world!

      Or did you mean that somebody else should do it?
    • The three-dimensional cells could also be useful in space applications, where power is in constant demand and launch weight is critical. Ultimately, they also could be used in developing nations where low-cost electrical power is vital to expanding economies.

      Missed this paragraph, did you?
    • it is probably a US army grant
      and they need some more money right about now
    • What about powering mobile computing systems for rural schools in India, or for use in purifying water in Africa?

      Until India and Africa come up with the money to drive this technology, they'll have to wait for those that are actually paying for it to develop it.

      Sigh.

    • Re:But not word... (Score:2, Insightful)

      by Adeax ( 167630 )
      Powering mobile computing systems for rural schools in India isn't mentioned because the rural school system of India isn't paying for the research - the DoD is.

    • Re:But not word... (Score:3, Insightful)

      by gmcraff ( 61718 )
      Remember that a lot of technologies start in military applications long before they move out to civilian use.

      Why is this?

      Firstly, because military problems attract money. Privates bitch to Sergeants, Sergeants bitch to Captains, Captains bitch to Colonels, Colonels bitch to Generals, Generals bitch to Congress, who has the people's money. If a private is too hot, too cold, too vulnerable, lacking ammo, too slow, too visible, etc, it becomes a problem that the Generals will address in order that the so

      • Look at the solid-state accelerometers and gyros used in state-of-the art automotives. (Subaru's Vehicle Dynamics Control, and the similar Volvo system they plug in their ads for the XC90, etc.)

        Take a guess what those solid-state accelerometers and gyros were originally created for...
      • Firstly, because military problems attract money. Privates bitch to Sergeants, ...

        Uhm, not quite. The real mechanism is...

        Privates DIE, newspapers and parents of dead privates bitch to Congress, who has the people's money.

        Same end result, of course.

  • 20 um vertical structures?!? (Score:4, Interesting)

    by Sebastopol ( 189276 ) on Tuesday March 01, 2005 @07:47PM (#11818159) Homepage

    preface: my nanotech is limited to semiconductor process only.

    looking at the image, the towers appear to be 20um cubes, and the tubes look incredibly uniform. That is some impressive feat to build such a tall structure!

    this makes me think of 3D model creation tools that use a laser and a tank of epoxy-like goop to 'draw' a 3D prototype of a design.

    can this accomplishment be extended to this technique to "render" nanodevices (er, microdevice machines), out of tubes?

    • 20um towers? OLD NEWS! (Score:1, Interesting)

      by Anonymous Coward
      This is really silly. The only thing new about this is the application idea. People have been growing multiwall nanotube towers since 1998... All the new nanotube field emission displays are based on them. Single-walled towers (which this MAY be refering to, but the article is too sparse to be sure) have been around for at least 2 years, vertical SWNT published first by Maruyama in japan, followed by a much better paper (all sorts of shapes of nanotube towers, up to 2.5mm tall... yes, MILIMETERS) by Iiji

      • Nanotube researcher--

        So can we fabricate things out of these tube structures, like that modeling I mentioned in the original post? Or are these more like tubes that carry liquids or individual atoms?

        Any word on what they are good for, or is it just a milestone in nanotech???

        --Someone fascinated by nanotech

  • a lot of solar news lately (Score:5, Informative)

    by grqb ( 410789 ) on Tuesday March 01, 2005 @07:48PM (#11818172) Homepage Journal
    So far this week we've had quite a bit of solar news...solar power airplane to fly around the world [thewatt.com], another breakthrough in solar power that brings the price of solar from $8/watt to about $1/watt [thewatt.com] and now this...hmmm I should get into this business it seems!


    Carbon nanotubes are also all over the map these days so why not nanotubes and solar? I guess we'll have to wait a while until this becomes commercial though because I don't think carbon nanotubes can be scaled up very easily.

    • Yeah. (Score:3, Interesting)

      by Grendel Drago ( 41496 )
      And I'm sure we'll have solar as a major component of distributed power generation right after that commercial fusion plant gets built.

      --grendel drago
      • One irony,

        Effecient solar energy is dangerous.

        Any solar collector in the hands of a moron could evaporate a target. You think ants have it bad - wait until your average home solar dish blows a gear and the focal point drifts into something else.

        BAM

        AIK

        • Re:Yeah. (Score:2)

          by njh ( 24312 )
          A parabolic dish has only one focal point, in the obvious spot. Furthermore, an off axis parabolic reflector cannot focus properly, so they only work when they are pointed in the right direction.

          The ?irony? is that people who post anti-solar posts invariably demonstrate that they have no clue.
          • First - I'm not anti-Solar.

            Solar energy is really the only renewable that has a positive correlation with Supply/Demand.

            Wind and Waves all drop out during peak months.

            I'm concerned about the saftey of concentrators in residential settings - I do understand the astimatism of a scewed reflector - how can we be sure that even with astigmatism, the focus will be rendered harmless?

            Is there a size limit?

            Fires occassionally start because of refractive materials - such as bottles in the wrong position - How ca

            • Re:Yeah. (Score:2)

              by njh ( 24312 )
              Ok, I was grumpy when I wrote that from the sheer idiocy I see on slashdot (makes me wonder why I even read it :). Sorry.

              I'm not sure what the model is for your steerable solar dish, are you thinking of having one per household? This seems unlikely as dishes only become reasonable around the 20m diameter mark, which would be too large for any but the largest houses. On the other hand, panels are economic even for 1cm squares for powering calculators. So I very much doubt that people will have their own
              • In order to conceive of a zero-carbon world which meets current per capita energy consumption for an dramatically increasing consumer base (think china with air-conditioners and hummers), We cannot take anything off the table - our buildings need to capture Solar energy at high rates of effeciency at competative rates.

                Assuming energy demand to be part heat, part A/C, part light, and part electricity, we should ask first how much of that could be extracted from a 40% effecient Solar roof, and second, how ca
    • You know, you'd figure that the entire field of solar power got one of those special deals with /. like the one Apple has...
  • Can someone tell details about how they do it ? The sighted news articles doesn't give any details. Can they grow individual carbon nanotubes vertically ? There had been earlier work on controlled alignment of carbon nanofibers [aip.org] from ORNL folks. Their technique could grow the nanotubes in different directions using electric field. There is also an option of controlling the direction of growth using polarized light.

    If precise formation as well as placement can be achieved, it will get over the biggest hurdle in getting into the electronics. There are still other issues (eg. contacts, surface adsorbtion etc) to be addressed though.

  • Hmm.... (Score:3, Insightful)

    by Squirmy McPhee ( 856939 ) on Tuesday March 01, 2005 @09:17PM (#11819172)
    The nanometer-scale scale towers, which would be coated by the special p-type and n-type semiconductor (p/n) junction materials used to generate electrical current, would increase the surface area available to produce electricity.

    Generally, increasing surface area on solar cells is detrimental to producing electricity, particularly if the semiconductor material is very thin. (Yes, I am well aware that it is more than counteracted by the additional light coupled into the cell, but the writer makes it sound as though increasing surface area is a magical formula for making more power. And the increase in surface area, by itself, is still detrimental.) I would very much like to know what are the "special" semiconductor materials they plan to coat the towers with.

    I don't think this is so much a breakthrough as it is just another in a long line of textured substrates for thin-film solar cells that don't even work yet and won't be hitting the market for another 10 years.

    Because their cells will be more efficient, Ready believes they can use older and more mature p/n-type material technologies and less costly silicon wafers to hold down costs and rapidly advance the project into products that can be used in the field.

    If he is going to use silicon wafers as simple substrates then his cells had better be substantially more efficient than standard crystalline silicon solar cells -- otherwise, he is guaranteed to be priced out of the market. Silicon wafers make up half the cost of a solar module, and the module materials and assembly make up another 30-35%. Assuming he can actually deposit these nanotowers and their semiconductor coatings at a cost similar to that of converting a silicon wafer to a silicon solar cell, it doesn't give him much choice but to leverage efficiency to get a lower cost per watt.

  • BLAR, damn you /. damn you

    When I hear towers of nanotubes, I'm thinking of god-damn space elevators

    2 microns is not exactly sky-scraping

    • Actually if you think about it, it is no less than a tower

      A typical carbon nanotube is ~1-5 nm in diameter. A 2 micrometer long nanotube means an aspect ratio (length/height to diameter) of almost 1000. Even the tallest skyscraper don't go beyond 7:1. WTC had height to width ratios of 6.49 to 1. Bank of American plaza has the highest with 7.24 to 1.

  • ...for the ultimate advance in environmentalism where we finally get to be as comfortable as we're shooting for with present tech and yet as organic as you can get: living everything. They're going in the right direction but this is very early nanotech theorizing. I'll wait for the nano-engineered biomechanical living buildings which eat all waste output from the residents, absorb ambient thermal and light energy, and are self-repairing. I'll be dead before they manage it, but it's a reassuring and hopeful
    • There are many applications for which mechanical methods are inherently superior to biological ones due to limitations of biological life. For example, despite its obvious efficiency, why do you think that no life on Earth has evovled wheels? Why are hydraulics not subject to the cube-square rule that limits muscular efficiency? How much food do you think it would take to feed a city of living skyscrapers, and how long would it take to grow them instead of build them? How would you air condition the bui
  • I was in DDL lab today and overheard some dude at random discussing your post on the front page of /. Congrats dude, you made it to the big leages. N|=

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