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Power Science

MIT's Millimeter Turbine to be Ready This Year 197

Posted by CowboyNeal
from the power-to-go dept.
Iddo Genuth writes "After a decade of work, the first millimeter size turbine engine developed by researchers at MIT should become operational by the end of this summer. The new turbine engine will allow the creation of smaller and more powerful batteries than anything currently in existence. It might also serve as the basis for tiny powerful motors with applications ranging from micro UAVs to children's toys. In the more distant future huge arrays of hydrogen fueled millimeter turbine engines could even be the basis for clean, quiet and cost effective power plants."
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MIT's Millimeter Turbine to be Ready This Year

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  • by Whiney Mac Fanboy (963289) * <whineymacfanboy@gmail.com> on Thursday February 08, 2007 @11:56PM (#17944142) Homepage Journal
    In the more distant future huge arrays of hydrogen fueled millimeter turbine engines could even be the basis for clean, quiet and cost effective power plants."

    WTF? Where's the hydrogen coming from? May as well say In the more distant future huge arrays of kitten engines could even be the basis for clean, quiet and cost effective power plants."

    Well, it could be!
    • by Max Littlemore (1001285) on Friday February 09, 2007 @12:00AM (#17944174)
      The hydrogen comes from the kittens, doofus!
    • by dbIII (701233) on Friday February 09, 2007 @12:54AM (#17944554)

      WTF? Where's the hydrogen coming from?

      From clean nuclear plants that require no mining, enrichment, hazardous waste disposal, have no concrete and so thus have no carbon dioxide impact and work far better than the tweaked 1950s dinosuars which are the only tested designs you could get built over the course of the next few years.

      Methane from kittens would be almost as difficult to organise.

      The proposal to "kickstart" the hydrogen economy consists of bizzare stuff like getting the hydrogen from methane - bizzare because methane is easier to ship, store and use and could come from biological sources (not just kittens) or from coalbeds.

      These turbines sound fantastic in very small situations and it appears a journo is missing the point by wondering what big arrays would do and setting up for dissappointment.

      • by Khyber (864651)
        Not to mention that even at that size, a large-scale operation of these would get to quite some noise level. Even a thousand whispers can get pretty loud.
        • by TropicalCoder (898500) on Friday February 09, 2007 @09:39AM (#17947080) Homepage Journal

          Even a thousand whispers can get pretty loud

          I beg to differ. Wikipedia [wikipedia.org] lists the sound pressure level of a whisper at 20 dBs. To calculate the sound of a thousand people whispering, we need to do 20 times log10(ratio). The ratio is 1000 whispers to one. log10 of 1000 is 3, so the SPL level of a thousand people whispering is only 3 time 20, or 60 dBs.

          However, though wikipedia does not state at what distance the SPL level of a whisper was measured, usually we would imagine that it would be a person standing right next to us, or certainly within a meter. Clearly you cannot have a thousand people standing right next to you. Even within a meter of you, considering perhaps two people per square meter including yourself, within a circle of a one meter radius you have only about 3 square meters - room for 5 people besides yourself at the centre. To accommodate a thousand people, you would need a circle with a radius of over twelve meters. Most of those people are going to be at least 6 meters away from you. Wikipedia says "Note that the SPL emitted by an object changes with distance d from the object with 1/d.", so that implies that well over half of these people only contribute a fraction of their potential to the total sound level.

          Beyond that, we have all these whispers generating an incoherent pattern of sound waves, sometimes reinforcing each other, and sometimes cancelling each other out, such that by the time this reaches your ears it has only a fraction of the energy that it would posses if everybody whispered in absolutely perfect unison, offset by their distance from you. In the end, the total SPL level is beyond my capability to calculate, but I would just guess that on a practical level it would not reach the level of a normal conversation between two people.

          Now, if you want to hear something loud, consider the sound of a thousand hands clapping. Going by the previous example, it is easy to calculate. We begin with an estimate of the sound pressure level of one hand clapping... Oh oh...

          • That was brilliant. It managed to be an actually interesting shaggy dog story (insofar as that's not a contradiction in terms).

            Well done, bravo, and all that.
          • by iplayfast (166447)
            I think this is one of the best comments I've ever seen on slashdot. Very well done!
      • Re: (Score:3, Informative)

        by mpe (36238)
        The proposal to "kickstart" the hydrogen economy consists of bizzare stuff like getting the hydrogen from methane - bizzare because methane is easier to ship, store and use and could come from biological sources (not just kittens) or from coalbeds.

        There is also a perfectly good methane distribution system in many parts of the world. Which even supplys the fuel direct to buildings. The only thing apparently lacking is bottled methane for easy use in vehicles. Though no doubt many existing fuel stations cou
        • Re: (Score:2, Insightful)

          by Radon360 (951529)

          Actually, extracting hydrogen gas from methane isn't bizarre at all. In fact, using a process known as steam reformation, it is the preferred way of producing hydrogen gas for industrial use because it is more economical than electrolysis. The industrial gas companies (BOC, Linde, APT) all use steam reformation to produce hydrogen.

          The only problem with converting methane into hydrogen gas is the same problem you have when you burn methane. It produces carbon dioxide.

          The key point to remember about hy

          • by ArsonSmith (13997)
            You could say that about pretty much all energy. The Sun is really the onlything around that is actually produceing energy, and even that is still a reaction of stored energy.
            • There are exactly two energy sources: Fusion and gravity.

              Fusion occurs in stars, H-bombs, and an infinitessimal quantity in man-made reactors. All fossil fuels on earth are stored fusion energy. Solar is obviously captured fusion energy. Wind is solar energy working on the atmosphere. Wave energy is wind energy distributed to the water.

              Tidal energy comes from the moon's kinetic energy, which is the earth's gravitational attraction of the moon.

              And nuclear fission is the controlled release of a little bit
    • Re: (Score:3, Funny)

      by brianosaurus (48471)
      Let's see... "Huge arrays of kittens" make a "QUIET [...] power plant". Yeah, right!

      I don't even want to think about the litter box.
      • by dpilot (134227)
        While you're busy getting power from your kittens, and worrying about the litter box...

        Here in Vermont we have several farms getting milk from their cows, and generating power from their "litter box." Fun thing is, once the manure comes out of the litter box after having done the methane thing, it's even *better* for fertilizing fields than the "untreated" variety.
    • Re: (Score:2, Funny)

      by kfg (145172)
      WTF? Where's the hydrogen coming from?

      Mr. Fusion!

      KFG
    • by Glock27 (446276)
      WTF? Where's the hydrogen coming from?

      Good point. Also kudos to the person advocating nuclear power, we definitely need to bump our nuclear electricity percentage above 50% (preferably far above).

      As to "huge arrays of hydrogen fueled millimeter turbine engines", various square/cube issues would seem to make the idea a non-starter. Larger turbines should be far more efficient, not to mention easier to make.

    • by mpe (36238)
      Where's the hydrogen coming from?

      There are rather easier fuels to obtain e.g. methane.
      Gas turbines don't tend to be too fussed about their fuel. Especially when not subject to the rather extreme environment of aircraft in flight.

      May as well say In the more distant future huge arrays of kitten engines could even be the basis for clean, quiet and cost effective power plants."

      Or even one based on "hamster engines". Maybe a hamster/kitten "hybrid" would be better. At least until the kittens got bored with
    • I think he's just confusing two different things -- a few mm-turbines running on hydrogen to power, say, flashlights and things, versus enormous arrays of them running on natural gas or something as a portable and inexpensive power plant.
  • by mi (197448) on Thursday February 08, 2007 @11:56PM (#17944146) Homepage

    In the more distant future huge arrays of hydrogen fueled millimeter turbine engines

    Imagine a, oh, whatever, cluster of these!..

    • by gbobeck (926553)

      Imagine a, oh, whatever, cluster of these!..

      I'm obligated to ask the following: ...But will it run Linux?
  • Huge arrays? (Score:5, Interesting)

    by Hektor_Troy (262592) on Thursday February 08, 2007 @11:59PM (#17944158)
    Doesn't turbines get more efficient as they grow in size? I mean, it's not like you'll see power plants use hundreds of tiny steam turbines - they use a few huge ones.

    Or am I missing something completely fundamental about the ones MIT's made here?
    • Re: (Score:3, Insightful)

      That's an interseting point. Perhaps the advantage is localised generation rather than isolated power stations. Perhaps they will be used in individual PCs, laptops, etc instead of batteries. I don't get how increasing the friction of a large scale system will increase it's efficiency, and I don't really get where the hydrogen comes from either.

      I'd be a lot more exceited about artificial photosynthesis

    • I was wondering that myself; don't small ones have square/cube problems? Anyone here know about this?
    • Re: (Score:3, Funny)

      by mainform (892764)
      Well, huge ones might be useful on a large scale but they aren't practical on a small scale, hence the smaller turbine :)
    • Yep... (Score:5, Interesting)

      by Goonie (8651) * <robert@merkel.benambra@org> on Friday February 09, 2007 @12:12AM (#17944288) Homepage
      This microturbine research pops up on Slashdot every year or so.

      The thermal efficiency is the real killer - according to this post [greencarcongress.com], the expected thermal efficency is somewhere between 3 and 8%.

      That's problematic for two reasons - one, a plant made of thousands of these would use way more fuel than one using a conventional piston engine and one generator, and, two, for small-scale apps it means you end up with a massive pile of waste heat to dispose of. As somebody put it - if you want 10 watts of power, that means 100 watts of waste heat to dispose of. Go put your fingers on a 100-watt lightbulb to get an idea of how much heat we're talking about...

      • Re:Yep... (Score:5, Funny)

        by CrazyJim1 (809850) on Friday February 09, 2007 @12:50AM (#17944540) Journal
        Go put your fingers on a 100-watt lightbulb to get an idea of how much heat we're talking about... Ouch, you insensitive clod.
        • Re: (Score:2, Funny)

          by alienmole (15522)
          I just put my fingers on the bulb and didn't feel anything. Wait, does that mean I'm an insensitive clod?
          • Re:Yep... (Score:5, Funny)

            by tftp (111690) on Friday February 09, 2007 @02:32AM (#17945150) Homepage
            No, it means that you need to turn it on first.
      • Re: (Score:2, Interesting)

        by 2Bits (167227)
        Ok, I'm a computer programmer (major in CS), and I don't know much about electricity, and electro-mechanical stuff. And the question I'm going to ask might seem like it's coming from behind, so please turn up your tolerance level a bit.

        I have an issue with dealing with heat here. Since almost everything must deal with dissipating heat, why can't someone invent something that collect the heat and re-use it to generate even more power? Everyone is putting a lot of genius into all kinds of methods to dissipate
        • Re: (Score:3, Interesting)

          by PsiPsiStar (95676)
          I'm not sure I totally parse what you're suggesting, but here's the basic concept behind heat engines; (anything that produces movement, and thus possibly electricity, requires a difference between hot and cold. The term for this is a heat engine. They're also called carnot engines. ) "Waste heat" is heat that isn't sufficiently hot compared to the heat sink to generate much energy.

          The energy generated by a heat engine is determined by the difference between the heat source and the heat sink. In other words
          • by shaitand (626655)
            But why not convert the heat directly into electricity without an intermediate mechanical generator? http://web.mit.edu/newsoffice/2001/electricity-120 5.html [mit.edu]
            • Did you read the article? The semiconductor in question operates at a minimum threshold of 250-400* C (about 480-750* F). I don't think that any part of the microgenerator reach these temperatures - the whole point of these things is to generate power without the unwanted side effects of regular sized generators (mainly massive thermal waste and the related material stress). It would be far more efficient (although they would take up a large area of space) to use a kind of reverse peltier device - one that
          • by sumdumass (711423)
            I think he is trying to suggest somthing like how a coal power plants work. It has a fuel source that heats a liquid (water?) which turns a generator. Then the water cools and it goes through the exhaust of the fuel sorce to captur some of the waist heat and start over.

            But i think he is suggesting doing this in combination with existing devices that generate heat like a computer's processor or somthing. then instead of letting the heat disapate into the air, It could create power to help supply the device.

            O
            • by ArsonSmith (13997)
              How about replace the radiator in my car with a steam engine/steam water reclamation device?
        • by evilviper (135110)

          Since almost everything must deal with dissipating heat, why can't someone invent something that collect the heat and re-use it to generate even more power?

          A few reasons (off the top of my head)...

          You need very high temperature differences to get any reasonable amount of usable energy. This precludes most heat sources, because the difference is small.

          If you try to get something to put out higher temperature waste, you adversely affect the operation of that device. Whether it's computers or air conditioner

        • Since almost everything must deal with dissipating heat, why can't someone invent something that collect the heat and re-use it to generate even more power?
          see combined heat & power [wikipedia.org] plants
        • Re:Yep... (Score:4, Informative)

          by Bander (2001) on Friday February 09, 2007 @01:52AM (#17944928) Homepage

          Since almost everything must deal with dissipating heat, why can't someone invent something that collect the heat and re-use it to generate even more power?

          Because of a little thing called the Second Law of Thermodynamics. Basically, if you use the waste heat to generate energy, you do so by exploiting the difference between the heat (probably stored in a medium that doesn't dissipate heat easily) and something else that's cold -- this makes the cold thing warm at the same time your heat storage medium cools down. Eventually, everything in your system reaches a uniform temperature, and the fat lady sings.

          If the universe is a closed system... http://en.wikipedia.org/wiki/Heat_death/ [wikipedia.org]

          More about the Second Law, including math and quotable quotes: http://en.wikipedia.org/wiki/Second_law_of_thermod ynamics/ [wikipedia.org]
          • by Gabrill (556503)
            Wast heat is being generated by the primary energy source. The cold part is the ambient temperature. How is this not a sustained heat difference until the primary energy source is depleted?
        • by Khyber (864651)
          Look into Sterling engines. that shoudl give you some insight into the limitations of the idea you're thinking. But, it may also give you ideas on how this could be used. For example, I use the heat from my two computers to keep my room warm in the winter. :) That's just a passive effect. You may find more benefit in using the difference between warm and cold temperatures to some degree, similar to OTEC stuff. Though I'm not sure how that could be done with anything other than the ocean. Keep on thinking
        • Re: (Score:3, Insightful)

          by maxwell demon (590494)
          Ok, let's do the math for some realistic example: Say, you want to generate energy from the waste heat of an Athlon 64 3000+ (I've taken this model because that's the first one I've found the required technical data. [planet64bit.de].

          Now the maximum temperature allowed for this procesor is 65C (that's 149F, according to Google), or 338K. Now let's assume that it's in a room with 18C (64.4F, according to Google), or 291K. Now let's assume you attach an ideal heat engine to your Athlon 64 (i.e. a heat engine which converts as
      • by Khyber (864651)
        Considering how powerful a hydrogen explosion really is with a proper accelerant mixture, at that scale I'd only expect about that efficiency, until we get far stronger materials.
      • by mpe (36238)
        As somebody put it - if you want 10 watts of power, that means 100 watts of waste heat to dispose of. Go put your fingers on a 100-watt lightbulb to get an idea of how much heat we're talking about...

        Some laptops can be bad enough when it comes to heat output just on conventional battery power. So who's going to be the first to make one with an EGT guage?
    • So we have a millimetre scale turbine. That's only half the electrical generation problem. How much of a coil can you make at that scale? How strong of a magnet can you have at that scale?
      • by dbIII (701233)
        I think the reporter missed the point on many levels - you would use this thing for mechanical work you want to do right next to where the turbine is. Forget the silly array idea when a big turbine would be so much better - think about stuff like rock drills with the motor at the head and just a fuel line going back or dozens of other tight situations.
    • by ceoyoyo (59147)
      Considering the number of errors in that article I just assumed the writer didn't know much about turbines.

      You're not the one missing something.
  • by TinBromide (921574) on Friday February 09, 2007 @12:00AM (#17944172)
    Who's willing to bet that within a week of these things becoming operational, they're put to use by some MIT nerds making a portable air hockey set?
    • Re: (Score:3, Funny)

      by edwardpickman (965122)
      It is MIT remember, it'll fit inside a matchbook and will have to be played with waldo arms but hey we did it. Wonder how many geek points they get for that one? Next challenge will be to make a Foosball table that will fit on the head of a pin and has to be played with a tunneling electron microscope.
    • Women everywhere will rejoice in the development of newer, more powerful...er...massagers.
  • by Loopy (41728) on Friday February 09, 2007 @12:06AM (#17944222) Journal
    This is all well and good but what about all the little bugs that will get shredded in those little turbines? Are they going to paste millimeter-size warning signs? I think it's the least we could do for our tiny houseguests.
  • by Speare (84249) on Friday February 09, 2007 @12:09AM (#17944250) Homepage Journal

    Yeah, it COULD revolutionize the whole world as we know it and make the Jetsons' lifestyle seem antiquated, OR...

    A toy company puts out a few gimmick Pokemon-tied concept toys long after the end of the Pokemon marketing age, and nobody buys them. Despite the technological benefits of using the power components, the company management gets a sour taste of market performance and buries the whole thing under ten feet of peat and recycles them as firelighters. The technology is not used by other companies for a couple of extra decades because of the patents and other intellectual property entanglements. It is finally redeemed and used in an inadequately-explained Elvis-Presley-tied concept doohickey comes out in 2040 and sells from a Hammacher Schlemmer catalogue for $20K but only if ordered from the seat pocket from LEO during a Virgin Galactic flight.

    • Well, I see I'm not the only one that caught Good Will Hunting on TV the other day.
    • Worse yet, I'd hate to see them go amok, fragment and get tiny & sharp turbine blades in my air supply. May as well go back to asbestos.
  • Moo (Score:5, Funny)

    by Chacham (981) on Friday February 09, 2007 @12:10AM (#17944264) Homepage Journal
    Millimeter Turbins? Must be for really small Muslims.
  • Gah! (Score:2, Insightful)

    by Anonymous Coward
    A micro-turbine is not a fucking battery! An ultra-capacitor is not a battery! A fuel cell is not a battery!
    • by QuantumG (50515) *
      Hey, if The Matrix can call a human being a battery, you can call ANYTHING a battery.
      • No, the matrix used the word correctly: they did in fact use an array of similar things together.

        Just like an electronic battery is an array of electrochemical cells for generating electricity, the matrix held an array of people for some vague use not actually related to power generation (they had "a new form of fusion power" for that). The characters however (Morpheus specifically), believed it was for power but Morpheus is an unreliable narrator [wikipedia.org].
        • by QuantumG (50515) *
          The reason why the machines kept humans around was clearly revealed by the reliable narator in the third movie: the architect. It's really simple: the AI isn't that great. They need humans for all those traditional AI sci-fi reasons: we're more creative, intuitive, etc.

  • Do they lift and cut as they're generating all that electricity, too?
  • by mdsolar (1045926) on Friday February 09, 2007 @12:29AM (#17944404) Homepage Journal
    The thing about these is that they are so small. The figures given are not all that much greater than the Li ion batteries, so in terms of applications is transportation, one does a whole lot better putting five 5 gal gas cans in your trunk for a 1400 mile range. For compact applications getting more power in a tight spot is a great advantage. If you are carrying a lot of electronics this really helps in reducing the weight. But, I'm not sure you'd want to use these to replace the two stroke in an chainsaw.
    --
    1000 W/m^2 http://mdsolar.blogspot.com/2007/01/slashdot-users -selling-solar.html [blogspot.com]
  • I hope this works out. I am interested in any invention that provides an environmentally clean method of power generation. The final goal of which is to increase the available per capita of energy. Forget conservation. The true progressive ideal is to find the means to allow for an increase in personal energy consumption.
    • Re: (Score:2, Interesting)

      by mdsolar (1045926)
      I agree, the motivation to conserve is to reduce environmental impact, (or to save money) but it is not a virtue in itself. I would rather not even use the word conserve. I'd much rather see a goal to eliminate the use of fossil fuels. In doing that, I'd like to create a situation where we can use as much power as we like, play with it, enjoy it, leave the lights on all night just for fun (though draw the shades cause I like to see the stars when I'm out at night). Right now we live in a scarcity driven
  • by GameMaster (148118) on Friday February 09, 2007 @01:07AM (#17944648)
    Let me see if I get this straight:

    He says that he expects the initial products to be about 500-700 Watt-Hours/kg. and to, potentially, go as high as 1200-1500 Watt-Hours/kg. in the distant future.

    My understanding is that this thing is supposed to run off of Hydrogen. It'd almost have, to as many consumer electronics are run indoors and most other fuels I know about give off toxic fumes when used in combustion engines.

    Hydrogen has an energy density of ~33.3 Watt-Hours/kg. ( http://hypertextbook.com/facts/2005/MichelleFung.s html/ [hypertextbook.com] )

    Now, assuming that the weight of the turbine (~4mm square) and packaging is negligible, most of the weight is fuel. In that case, we are looking at an efficiency of 1.5% - 2.1% for the initial models and 3.6% - 4.5% for the extreme upper end of what this guy thinks is foreseeable with this technology. 1.5% - 4.5% efficiency? That's horrible! Remember, pure hydrogen doesn't exist naturally on this planet. You had to spend large amounts of energy in the first place to produce the hydrogen that will be stored in these batteries (how exactly they plan on storing it I don't know because even the best, present day, techniques leak like a sieve because of the extremely small size of the hydrogen molecule).

    Don't get me wrong, I can see where people would want something like this. The potential energy density compared to the compact form factor would open up new possibilities for portable equipment. There in lies the problem. The instant gratification of this technology will be almost impossible to fight. If every piece of small electronics had this kind of power source, cell phones, PDAs, laptops, etc. would become leaps-and-bounds more powerful and, at the same time, would be consuming energy at, potential, an exponentially higher rate.

    The only way I can see this not becoming ubiquitous is if some other technology, like batteries, beats it to that energy density level. I don't think that's likely to happen because, even at these miserable efficiency rates, liquid fuels still have a massive lead in energy density over even the most promising, potential, battery technology known.

    I hope there is an error in my math. Another possibility is that, as is so often the case, the author of the article doesn't have a clue of what he's talking about and had warped the facts of the story. The fact that he has suggested the possibility of replacing full-sized power plants with massive arrays of these turbines gives me hope that that's the case. If any of you have a correction for my math, please let me know.

    -GameMaster

    • by mdsolar (1045926)
      You've got a typo which threw me, you want 33 kWh/kg. But isn't a low efficiency to be expected? One wants a big delta T for high efficiency and that is going to be hard to achieve on small scales. However, if these are very durable, connecting them is series rather than in parallel might get you something. You might build up to a very high delta T having one feed into another. But, then you've just built a modular large turbine so there might not be any point.

      Since fuel cells don't depend of delta T,
      • Ah, yes. I did intend that to be 33.3 kWH/kg. The math should still be correct though as far as the efficiency values are concerned. I typed 33.3 WH/kg. but assumed 33.3 kWH/kg. in my calculations.

        Everything I've ever heard about turbine engines suggests that the smaller they get the less efficient they are. The efficiency numbers are completely in the realm I can believe based on that. I guess I was hoping that someone would find a mistake to suggest that the efficiency wasn't quite that bad. One pot
    • by khallow (566160)
      They're not going to achieve optimal energy densities because of the difficulty of storing hydrogen. Storage will probably be a metal hydride or a pressurized container. Both will substantially reduce the energy density.
    • by mpe (36238)
      My understanding is that this thing is supposed to run off of Hydrogen. It'd almost have, to as many consumer electronics are run indoors and most other fuels I know about give off toxic fumes when used in combustion engines.

      Steam is quite nasty when hot. Also if you are burning in air you need to be careful about nitrogen and oxygen reacting...
  • by Bob54321 (911744)
    What is a UAV. Is it like an SUV but smaller - Urban Ant Vehicle?
  • Please can I have one of those micro SUVs...

    Oh its UAVs... thats a shame!

  • It might also serve as the basis for tiny powerful motors with applications ranging from micro UAVs to children's toys.

    Hey, anyone here have Micro Machines [wikipedia.org] as a kid? Imagine having a Micro Machine jet with real working engines.
    • by lahi (316099)
      Oy! I'm a modeller - haven't been into flying models because the damn things are just to BIG for my taste (and available space.) But imagine having a whole squadron of remote controlled 1/350 F-14's flying in close formation in the living room, and practicing deck landings on a Tamiya carrier!!! THAT would be cool!

      -Lasse
  • With this device, you can finally play the smallest electric violin for someone! Weeeh!
  • If you read the fine print of the article, you see, and Don't see:
    • How to cut and lift the rotor off the silicon base. ( Difficult, slow, and sloppy)
    • How to balance the rotor to one part in a million.
    • How to overcome the bad effects of scale (boundary layer, and friction)
    • The efficiency of the device, vs larger turbines (is very poor)
    • How to couple the rotor to a generator.
    • How to build a generator of the same size.
    • The cost of the device compared to the competition.
    • The thing HAS NOT BEEN RUN YET.

    So n

    • microgenerators (Score:3, Interesting)

      by mdsolar (1045926)
      At least one of your objections has already been covered on slashdot. http://science.slashdot.org/article.pl?sid=04/11/ 2 5/1331227 [slashdot.org]

      This link also covers the effort reported in the present post. Your comment on the efficiency of the proposed turbine anticipates some comments here. http://science.slashdot.org/comments.pl?sid=130810 &cid=10918320 [slashdot.org].

      It was one of Bucky Fuller's favorite things to point out that heat management becomes easier with scale since the ratio of surface area (where heat escapes)
      • >It was one of Bucky Fuller's favorite things to point out that heat management becomes easier with scale since the ratio of surface area (where heat escapes)-to-volume (where heat is stored) goes down in inverse proportion to the increase in linear dimension. This is why he felt that enclosing cities with his domes would be a good idea. --

        Yep, that's another problem with this turbine-- how do you generate hot gas for it? There's a certain minimum size for a flame-- any smaller and the surface area

  • If I have a little milliturbine battery with 3 turbines, each rotating in one of the X, Y and Z axes, their combined gyroscopic motion will resist being moved in any direction. It's as if the battery is heavier - the faster the spin, the heavier the battery.

    If I rotate the milliturbines backwards, will it get lighter, until the battery weighs nothing?

    And can I move the turbines off the power the battery produces?
  • "with applications ranging from micro UAVs"...

    The Diamond Age? =)
  • The MIT microturbine is interesting, but in the "what can you do for me today" category, the IHI Dynajet caught my eye.

    Product PDF :: http://www.ihi.co.jp/ihi/file/technologygihou2/100 04_6.pdf [ihi.co.jp] which mentions this interesting phrase:

    The Dynajet 2.6 is also undergoing development of mobile dry toilets featuring its Merit (3).
    From :: http://www.ufto.com/clients-only/uftonotes02.html [ufto.com]

    Originally built for military and civilian use, IHI's Dynajet 2.6 KW microturbine genset is selling commercially in Japan is 1.2 million Yen (about $9000) "for use in Japan only" (kerosene fuel). There are no plans for export. They don't have a natural gas version. Very little information is available, though I do have a 2-page product description and spec sheet (*available). The unit measures 30"x10"x11" and weighs 140 lb. [The contact at IHI prefers not to be listed.]
    from (PDF) :: http://www.jaif.or.jp/english/aij/member/2003/PDF/ May.pdf [jaif.or.jp]

    Last year, about 90,000 small power generators were sold in Japan. Japanese manufacturers are now working hard to expand their sales and add new models to their product lines. IHI Aerospace, for example, has released a portable model, the Dynajet 2.6, driven by a microgas turbine. Fueled by kerosene, which is easier to store than gasoline, the generator retails for ¥1.2-1.3 million ($10,100-10,900). It is the lightest gas turbine-driven model on the market. The company is also developing a cogeneration system that utilizes waste heat from gas turbines.
  • These little engines resemble a modified "Tesla" bladeless turbine, with internal winglets such as in the experiment [phoenixnavigation.com] by Phoenix Turbine Builders Club [phoenixnavigation.com] back in March of 2002. From their article:

    Based on other experimenter's test results with direct combustion and the Tesla configuration, we should expect our overall fuel to shaft efficiency to come in around 31% -- placing our design right between gas piston and diesel piston efficiencies.

    Wouldn't it be interesting if MIT engineered a bladeless turbin at

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