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Technology

Flywheel Energy Storage: Steel Yourself For Carbon 149

Red Leader. writes: "Hey. Here's an interesting article on flywheels and the future of batteries from Wired Magazine (8.05). Nothing super-promising yet (as always; vapourware) -- but down the road, these could make your laptop 'spin' a little longer." I'm a big fan of simple machines, and flywheels are one of my favorites. The mention of carbon nanotubes is especially interesting -- it'd be neat to see that technology enter the mainstream.
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Flywheel Energy Storage: Steel Yourself For Carbon

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  • by Anonymous Coward
    I'm just a computer scientist so this explanation is bound to have some bugs. I think the magnetic bearing play two roles here. 1. One is to keep the cylinder suspended. Less physical friction, the better. 2. The magnets may also be used to rotate the cylinder itself. If you've ever broken apart electric motors (at least the ones that were in small race cars I destroyed as a kid), the magnet doesn't completely envelop the cylinder. The cylinder has a charge opposite of what the outer magnet has. The opposite charge rotates the cylinder a little bit. Normally the cylinder wouln't keep turing because before completing a circle, the opposite ends of the magnets would meet again which would basically keep our magnatized cylinder stationary. However, just before the opposite ends of the magnet meet for the second time, demagnatize the cylinder and let it rotate (momentum, inirtia, I forget which one). Just as soon as the ends pass, re-magnatize the cylinder--the ends push off each other again--continue! At least in the motoros of my broken toys, the cylinder was magnatized through wrapping a fairly large amount of copper wire around it and connecting it to a battery. Just make the cylinder so as it rotates, it makes then breaks the wire-battery circuit at just the right moments. Despite my explanation, it is actually a fairly simple process (as far as I can tell).
  • ::but if you were to jump up in the air, you would find the station would spin out from under your feet, and you would not land in the same place you jumped from:: Try doing so on a train. you have the same forward momentium as the train. If the station were to STOP you'd fly into something.
  • Anyone thought of building a huge flywheel on the equator with the axis pointed toward the center of the earth? The rotation of the earth would rotate the axis of the flywheel and cause it to accelerate (ignoring inefficiencies) How efficient would a flywheel have to be for this to be break even (probably very)?
  • I still have major misgivings about the safety of storing so much energy in flywheels. Look around you and imagine if all the parked cars you see actually contained more kinetic energy that they would have while motoring down the freeway. Now imagine what happens when two of these flywheel enhanced cars collide -- it wouldn't matter if one of the two were parked or moving.

    Paired flywheels might balance out the precessional forces under normal conditions. (Though slopes of up to %26 occur in my city, and slopes in excess of %15 are very, very common.) But paired flywheels would actually have more failure modes to account for.

    It seems to me that any flywheel in a vehicle would have to be engineered to safely return to a zero energy state under any and all conditions. I cannot imagine how that could be done.

  • This would be a great feature. Think about it, If you bumped it, you could have only a few inches left on the table but because it wouldn't want to flip over, it'd stay on the table...
  • Guys - think of it like the integrators used by Vannevar Bush in his Differential Analyzer [mit.edu] built at MIT - you can see them in the third picture down. Now, these used a metal knife edge wheel turning a larger glass disk (set perpendicular to the knife edge wheel) to perform integration. The knife edge wheel could move radially in and out on it's shaft, varying the speed at which the glass disk turned (I think the knife edge wheel turned the glass disk - but it may have been the other way around, what with the torque amplifiers used on the shaft of the knife edge wheel - anyone know for sure?). To envision the flywheel system being imagined:

    Replace the glass disk with the flywheel, and the knife edge wheel with a motor driven rubber wheel - allow it to move in/out via some mechanism (no need to move the motor, allow the motor to remain stationary, and move the rubber drive wheel along the shaft, radially to the center of the wheel).

    That should make it clearer...
  • Counterrevolving pairs of flywheels don't work well as a substitute for good gimbaling. The reason is that, while the *external* forces are nulled out by the counterrevolving aspect, the *internal* forces remain every bit as huge. Because there's no force feedback to the outside, it becomes VERY EASY to trash the main bearings: even a very slight, effortless rotation of the main case causes incredible, huge (opposing) torques to develop in the two main bearings -- which then stop working (crash, boom, tinkle).
  • The way I read it putting them in a vacuum is't common practice, although I may very well be wrong on that. Still, how do you get a vacuum chamber w/ magnets & a spinning disk that has enough mass into something less than an inch thick?

  • Gyroscopic effects can be neutralized simply by running two identical flywheels in opposite directions.
  • Actually, the hopefully soon to be launched Phase3D Amateur Radio satellite uses 3 flywheel like devices (they call them reaction or momentum wheels) to allow the satellite to stay oriented properly in 3d space.
    Check out http://www.amsat.org/ and
    http://myweb.magicnet.net/~phase3d/newpics/solar .html
    (They've got lots of good technical info on how they solved lots of the technical aspects of keeping a satellite up... Even heat dissapation is complicated without air.)
  • Actually, with the flywheel, you can simply power things through the flywheel, as opposed to 'switching'. (same as UPS theory). Especially given the theoretical longevity of the flywheel. Power the huge underground flywheel, and the flywheel powers your city. Feed power to flywheel disappears, flywheel keeps going until it expends all it's stored energy.
  • Just thought I'd elaborate on the previous reply to this post. I'm good friends with one of the engineers working on the flywheel bus project at CEM, so I've gotten to check out a lot of their work. If you think about it, the average vehicle remains almost completely level all the time. Even fairly steep hills are generally less than 5 degrees (a 6% grade, which is quite a lot, is only 3.43 degrees). The gimbals upon which the flywheels are mounted allow 10-15 degrees travel from the verticle axis. The flywheels are, or course, mounted so that the axis of rotation is verticle, allowing the bus to turn without any problem. The system to return the flywheel to vertical is gravity-based, with the mounting point of the flywheel battery within the gimbal placed slightly above the flywheels center of gravity. Being an electrical engineer, I find the mounting and mechanical aspects of the design interesting, but the electronics required for the complete system are even more ponderous. Precise, simultaneous control of six three-phase motor/generators is required: four traction motors mounted directly to the bus wheels, which also act as regenerative brakes; the flywheel battery motor/generator; and the generator attached to the diesel motor. In addition, this control system must also set the throttle angle of the diesel motor based on the current energy demands of the bus and flywheel system, etc. It's quite a piece of work, but I'm looking forward to seeing it all in action out on the city streets here. Hopefully we'll all be buying cars with flywheel batteries and fuel cells in the not-too-distant future as well. phil
  • no, you're wrong. in your bullet example, before the impact the momentum is m*v while the energy is (m*v^2)/2 Note (a) how different the units are and (b) you can't convert one to the other.

    furthermore, immediately after the non-ideal impact of a bullet, the energy dissipates as a variety of things (heat, kinetic, sound, etc) but the momentum is strictly conserved.

    as far as the relativistic effects you describe (which would not really impact our flywheel), my memory of that stuff is much more fuzzy, but momentum remains different from energy.

  • by Anonymous Coward
    How the magnetic bearings work (esp. in the presence of the magnetic field produced by the motor/generator).

    In a well-designed system, the manetic bearings will not be affected by the motor/generator. The respective magnetic circuits can be well-isolated from one another.

    How they measure rotor position for feedback to the magnetic bearings.

    Rotor position can be measured in a number of ways, including capacitive, inductive and (probably) optical sensors (although this one would make me nervous). If you're really clever, you can combine an inductive sensor with the force coils for the mag-bearings and save yourself a set of coils, but this is tricky. Practical systems can measure rotor displacement (known in the field as 'runout') to a fraction of a mil (1/1000").

    If it's a motor/generator, there must be a rotating magnet. Is it intregated with the flywheel, or attached to the side, or what?

    There need not be a permanent magnet in a motor/generator... see induction motor, synchronous reluctance motor, etc. In fact, there are compelling reasons NOT to include rotating permanent magnets in a flywheel, such as elimination of parasitic losses due to eddy currents in motor/generator windings. However, some systems do incorporate permanent magnets.

    - j

    PS: These things are EXTREMELY tough in practice to make work... there are engineering challeges in many different disciplines that need to be solved simultaneously, which is probably why no one has gotten one to work reliably and economically yet (despite the conceptual simplicity).

  • by kornack ( 43631 ) on Saturday May 20, 2000 @11:13PM (#1058472) Homepage
    I've long loved the idea of flywheel cars but have always worried about the gyroscopic effects.

    Consider a car with a flywheel in it. If the flywheel lies in the horizontal plane, its axis of rotation (and, thus, its moment of inertia) is vertical. If such a car were to turn on a flat road, nothing would happen. But if this car were to drive onto a ramp, the flywheel acts like a gyroscope and would cause the car to violently turn to the left or right.

    Likewise, if the flywheel is oriented so that the axis is horizontal, any turn to the left or right would cause the car's nose or rear to pluge into the ground. The exact direction would depend on the direction of rotation.

    What am I missing in this account? Am I simply wrong to think that the precessional force would be so strong? I haven't checked any numbers for myself, so it could be that the effect is sufficiently weak. Indeed, the bus that was described in the article didn't seem to flip over. Of course, it was just using the flywheels as temporary storage for acceleration in combination with hybrid power (right?). So perhaps its flywheels are smaller than the ones I'm envisioning as replacements for the batteries in modern purely electric cars.

    The solution that I see is to place two counter-rotating flywheels right next to each other so that the total moment of inertia is zero. There would be tremendous stresses on the support structure for the flywheels, but the sum moment of inertia is zero.

    Tom Kornack
  • To increase the amount stored, you can make the wheel heavier, or spin it faster.

    Seems to me that there's only three ways to power a laptop w/ a flywheel:

    • Make it so heavy that it's impractical
    • Make it spin so fast that it's too hot to hold
    • Make it light, spin it at a reasonable speed, and get 10 min. use before you need to recharge

    Even with a Crusoe chip I don't see this being practical.

  • Actually, I'm most intesteted in a clockworks-driven laptop power supply. I've seen spring powered flashlights - it seems silly, but consider how useful one would be during a prolonged power outage. No batteries needed. A wind-up laptop would be a wonderful thing...crank that sucker!

  • Now THAT is funny as hell.

    My .02
    Quux26
  • ...and of course the gyroscopic effects.

  • The advent of the water dam and the diversion of water for irrigration purposes has shifted water toward the poles of the earth. Just as a figure skater brings in her arms to spin faster, our planet would spin faster if the moment of inertia is decreased in this way. Someone has claimed to actually calculate this effect. It was an article on the back of the main section of the New York Times a few years back.

    Tom Kornack
  • by flanagan ( 35585 ) on Saturday May 20, 2000 @11:31PM (#1058478)
    They solve the problem by mounting the flywheels on gimbals. When you turn the car, the gimbals allow the flywheel to maintain its axis without jerking the car around. This was described in the Scientific American article referenced above. I read it ages ago, but remember it because it was so cool!

    They also use the wheel's own momentum to power the electromagnets used to suspend the flywheel in its chamber, which I thought was rather elegant.
  • How do you heat one of these cars? The same way Volkswagen did it in the original Bug, with a gas heater.

    It's a trivial issue.
  • If you have two counterrotating flywheels, then their angular momenta are in opposite directions, but since energy has no direction (it's a scalar), the energies just add. So you still have positive energy with counterrotating flywheels.
  • I've been pretty satisfied by what I've seen of flywheel safety enclosures, so that's not too much of a worry. Precession is only a problem for a flywheel when off-center torque is applied. Proper mounting of the fly-wheel and proper design of the control system for the magnetic bearings take care of this problem and negate the need for a second flywheel. As for heat problems, mounting in a vacuum and using magnetic bearings certainly help to cut down on friction-generated heat, which is very important (of course, these are necessary to get acceptable efficiency out of the system anyway), but they create problems of their own. If you think about it for a second, you'll realize that the flywheel and rotor comprise a system which, during normal operation, touches nothing and is surrounded by a vacuum. It's still going to get hot, though, because of the induced current in the rotor windings. Where does this heat go? There's no convection or conduction, so the only cooling path is through direct radiation, which is very inefficient. High efficiency motors and electrical noise reduction become VERY important in flywheel design for this reason. phil.
  • youre essentially correct about the less energy part, in fact it states that explicitly in the article you link to

    To paraphrase a popular Pontiac automobile commercial tagline, "slower is better" in Ellis' view. His PowerBeam flywheel, operates at half the speed of the Oakridge device. Of course, this means it stores only a quarter of the energy, but it also produces only a quarter of the stress on the device's components.

    As for the axis problem, counterrotinting does solve this, in the same way it solves the torsional problem when you spin the flywheels up. Say you have two flywheels, each rotating in opposite directions, and they are encased in a sturdy sheilding material. The angular momentum of flywheel A is X N*m/s along the k-hat direction, the angular momentum of flywheel B is -X N*m/s in the k-hat direction. If flywheel A is bolted securely to flywheel B, the net angular momentum of the system is the sum of flywheel A and flywheel B which is 0. Now, youre right that when you turn that forces will be generated, A and B will try to precess in opposite directions and tear themselves apart, but as long as you have your wheels cases bolted together well enough, and your magnetic bearings are strong enough, it shoudnt be a problem. also, if A doesnt have the same mass or rpm's as B, youll have turning problems too, but were assuming that the flywheels are identical and have the same rpms.

    On the other hand, if you used gimbals, you could make one kick ass vehicle, that would be able to turn on a dime, you could replace the conventional front wheels with just one big roller, that could rotate freely, and use the gyroscopic efect to relace friction as the rotating mechanisim, but I digress.

  • by WombatControl ( 74685 ) on Saturday May 20, 2000 @09:36PM (#1058483)
    Carbon nanotubes could be the energy source of the future. Not only are they useful for flywheels as the article mentions but they also are being tapped for use in hydrogen fuel cells. The nanotubes can trap hydrogen and make it safe for storage and use as fuel. The nanotubes need to be able to carry 6.5% of their weight in hydrogen. Some researchers have claimed that they have formulated nanotubes which can hold up to 65% of their weight in hydrogen but those results have not been revealed because of "commercial reasons." (Don't these people ever learn? You're not going to make a cent unless your process stands up to scientific review!) Still, carbon nanotubes are an exciting new prospect in the quest for a cleaner burning engine system. Between hydrogen fuel cells and flywheel power, the prospects of these structures are enormous.
  • by Anonymous Coward
    And gyroscopic forces simply need to be balanced. If you had two wheels on a typical demonstration gyroscope, spinning in opposite directions at the same rate, the gyroscopic effects completely disappear.

    For the outside, yes. But for the bearings these wheels run in, the forces would be quite real. So even if you don't feel it on the outside, the bearings and mounting frames that hold the 2 wheels will have to be able to take the highest possible forces plus a safety margin. You do not want a full powered flywheel to break loose, you really do not want this to happen...

  • Just think... with a hydro-pneumatic, 120% capacity cold fusion perpetual motion flywheel array in my laptop...

    Quake 3 would FLY!!!!!
  • Charles Sheffield, One man's universe, The continuing chronicles of Arthur Morthon McAndrew.

    Really hard Sci-Fi. Weird stuff. Although the literary quality is nowhere near, say a Iain Banks or Gibson, the Sci part of it is impressive.

    Does anyone know about more Sci-Fi novels written by this man?
  • Wow. Thats pretty cool. However, I was wondering if you knew how far the research has come with these Nanotubes. For example, has there been any actual experimentation yet, or have scientists only been able to formulate some expected results? And, if you know the answer to that, when do you think nanotubes will have developed enough to be an effective inexpensive alternative to consumers?


    --------------------------------------------
  • Does the Coriolis Effect have any influence over the operation of these? One would think there would be gyroscopic forces at work here...

    Does anyone remember "Shipstones" [wegrokit.com] from Heinlein's books? They were a super-efficient non-lossy energy storage unit, which were so sophisticated in design that the inventor didn't even bother to get a patent, because (supposedly) they were almost impossible to reverse-engineer.

    Heh; well, you can't be right about everything, I guess...

  • I am having a hard time deciding which is cooler, flywheels or thermophotovoltaic [wwu.edu] generators. I guess I will just have to hope for a tpv/flywheel electric hybrid car to be made. That would seriously kick ass.
  • "which were so sophisticated in design that the inventor didn't even bother to get a patent, because (supposedly) they were almost impossible to reverse-engineer. "

    Wasn't that what IBM said?


    --------------------------------------------
  • Oh, so if I have one gyroscope here in my town and I get you to start one turning in the opposite direction over in your town, and we both simultaneously turn them upside down, angular momentum adds to zero and there's no gyroscopic effect for either of us?

    You're correct (the above example works), with reference to the system, from a point of view outside the system. But each of the counterrotating parts creates its own separate angular momentum, and the axle or frame that you do the adding with (in this example, our hands and bodies connected by the earth) has to be one strong MF to handle the kind of changes in angular momentum that go with rotating the axis of flywheels that can run a car... And you have the problem of coming up with bearings that take that stress without burning up or wobbling.

    Sorry, I remain skeptical that such a system is practical for those kinds of flywheels.

  • A laptop with a charged-up flywheel in it might exhibit some interesting gyroscopic effects... you could pick it up, but wouldn't be able to turn it upside down?

    One other thing... I'll be really impressed if they manage to make the same spinning disk do double-duty as both hard drive platter and flywheel.

  • by trims ( 10010 ) on Saturday May 20, 2000 @11:34PM (#1058493) Homepage

    Pardon the silly title.

    yes, even the smallest flywheel has gyroscopic precession problems. Yes there is a danger that they might shatter and shoot out lots of nasty fragments. Then again, your typical battery can spontaneously burst into flames, spew acid all over the place, and generally trash your surroundings at the drop of the hat. I don't see too many peole complaining about those problems.

    The precession problem with flywheels can be almost completely negated by using two counter-rotating flywheels. yes, I am aware that there will be some problems with movement along the Z-axis, but this is managable in instances where there is little Z-movement (such as cars).

    Furthermore, the heat problem is significantly reduces (in fact, almost eliminated) if the flywheel is contained in a sealed vacuum shell. For safety's sake, making this shell from something like kevlar would reduce the small risk associated with flywheel failures at high speed.

    The biggest problem with using flywheels is that there has to be some sort of electric motor - that is, something that can change mechanical movement to electrical energy. In items like cars and UPSes, this isn't much of a problem. In your laptop (and similar compact places) this is definately a stumbling block. I wouldn't look for flywheels in laptops anytime soon.

    I expect to see flywheels in electric cars in the near future, since they offer alot of advantages over a most batteries: lighter weight, a very high energy capacity, ability to deliver large amounts of current quickly (something most non-lead-acid batteries can't do), and virtually no maintenance.

    Honestly, I can't wait for the hybrid car to come along: small, constant RPM gasoline engine, electric generator, and flywheel. You have a lead-acid to start the whole thing, and store any excess energy in the flywheel. Cool!

    -Erik

  • Perhaps the entire flywheel mechanism could be put in a cage that pivots on three axes (like those "human gyroscope" things at carnivals) so the moment is always perpendicular to normal?

  • Maybe a wind-up laptop would be a bit far away, but I think a wind-up cdrom-drive in a laptop would be very neat; spinning up the cdrom-drive eats a lot of energy which you can all save this way. For ppl that only use cdroms occasionally this would be usefull, i think. The same goes for discmans (cd don't spin as fast in them), walkmans etc.
  • Slashdot [slashdot.org] already had a discussion about a different type of batteries people are successfully researching on.

    Motorola claimed it would be 3-5 years away from producing Methanol based fuel cells with at least twice the energy density from todays batteries. These batteries should also be safe from most of the problems associated with current technology (memory effect, fuel exchange instead of timely recharge...)

  • Do you realize that you basically regurgitated the article? I read the comments to maybe get some alternate opinions or insight, not the Readers Digest version posing as.

    My .02
    Quux26
  • I agree. . .Check this out!!

    http://www.survival-tech.com/litemain.htm [survival-tech.com]

    VERY cool.

    -S

    http://students.washington.edu/steve0/ [washington.edu]
    steve0@u.washington.edu
  • I'm sorry but I just don't see the connection between Carbon Nanotubes and Flywheels.

    Can someone please enlighten me...


    Nathaniel P. Wilkerson
    NPS Internet Solutions, LLC
    www.npsis.com [npsis.com]
  • I'm not much of an expert on physics so someone might want to correct me here but they're talking about using conventional motors to spin these disks up.

    My question is would it be possible to introduce alternating magnetic particles (in a permanant arrangement) around a track of the disk somewhere near the centre? You could then use these to accelerate or draw power out of the disc directly. This eliminates all friction imposed on the disk and as such the only thing slowing the disk down translates to actual power output.

    You could use magnets around the outside area of the disk for suspension and stabilisation and I'd assume this could simplify design somewhat.

    Is there a reason why this isn't being done?
  • Wow -- sounds sorta like what I had been thinking of, oh maybe 7 years ago. And I was born in 1985. So hmmm... maybe I should listen to my absurd ideas a little more...

  • Do a sun-and-planets type gear system. I can't really remember exactly how it works, yet alone explain it without a picture, but basically what you get is the ability to control the gear ratio by (I think) a little electric motor.

    You don't really need it to vary continuously, though -- some skillz with the conventional gears could accomplish the same thing with a less mechanical effort.

    Finally, connect the pedals directly to the power train (oh yeah and of course you'd need to add a neutral setting) and charge up by pedaling really fast before you come out in front of everybody, and pedaling lighly as you go along. Yeah that really would be cool.

    A sensible "pedal"-gear size should avoid the Darwin risk.

  • >Which in itself resolves a fundamental problem,
    >emissions, which are a very serious problem,
    >getting worse, in most countries.

    Well, it doesn't really solve it, it just pushes the emission generation away from the car. You still have to generate the power somewhere, and most countries burn fossil fuels to generate their electricity (including over half the power in the US I believe). The only practical alternative to that is nuclear power, and Greenpeace et. al have pretty much put paid to any new nuclear power development.

    So, while electric cars, and now flywheels, sound cool, keep in mind that the power will still be coming mostly from burning fossil fuels with all the pollution that entails.
  • Redhat, Debian, etc.. make profits from selling their distributions, so profits aren't all bad.

    Debian does not sell their distribution; they are a nonprofit team of volunteers. If you want the distribution you either download it or buy it from cheapbytes, Corel, etc.
  • But if you move the energy production to a place that can do it more cleanly and efficiently (like a city power plant) and away from the internal combustion engine, then it's still a net good.
  • Forget bulky 25 pound flywheels rotating at a mere 60,000 RPM...
    Acheive the same thing by rotating a nanoscale 1 miligram flywheel at 208 Million RPM.

    Wee wheels win windfall -- news at eleven

    Weesner

  • From the article, talking about a cable SP installation:

    Once the wheel is in place, it is monitored and controlled remotely via a local server plugged in to the Net...

    Can you say security risk? Send a killer poke to a flywheel spinning at >60,000 rev/min, and watch the carnage fly...

    Of course, that's assuming they sell out and use WinCE for their flywheels... if they use an embedded Linux, then it's no problem. *grin*

  • I recalled seeing an article on Time magazine one or two years ago, mentioning the possible application of flywheels on automobiles. The point is that with a mechanical energy storage device like that, you can easily reclaim energies from, for example, speed brakes, which are normally turned into heat and dissipated into the atmosphere.

    However, there are still problems that were not satisfactorily answered AFAIK. Basically flywheels work by storing energies as kinetic energies of a spinning disk. So in order to increase the amount of energy stored, either you have to increase 1) the mass of the wheel, 2) the size (diameter) of the wheel, or 3) the spinning speed of the wheel. None of which seemed desirable.

    After all, the most undesirable properties of batteries are: 1) heavy, 2) bulky, 3) potentially dangerous. Just imagine what would happen if you drop such a device to the floor with an 1 Kg plate spinning at over 10K rpm... you get the idea.

    Anybody have insights into this one?

  • listen up little girl ( you are a girl since you have no penis! ) if you knew the answer, why not just show your knowledge rather than abusing the poor ignorant soul.

    since you obviously didn't know the answer:
    A flywheel is a heavy wheel on a revolving shaft used to regulate machinery or accumulate power.
  • by uninerd ( 79304 )
    Sorry, but as a high school AP Chem student, I'd have to disagree with your notion that this is a possible reaction

    (H20 + {N2, O2, etc} -> products + energy)

    the reason being that there is very little free energy contained in the molecules of any of these abundant environmental compounds; with the exception of hydrogen- but there's not too much of that floating around close the ground on earth... it tends to react chemically, or waft off up into the stratosphere.

    A fuel cell is usually based on O2 reacting with H2 (great, huh? why not get all our power that way?) (becasue there's on source for the H2; we have to electrolyse it out of water, a process that requires more energy than it yeilds) so the possibility of ambient air chemicals yeilding energy... nah- it would be happeneing in nature right now, since entropy likes stuff to fall all the way down to the lowest stable energy state.
  • As far as I know there's no such thing as an alternating permanent magnet, and I'm a physics undergrad who's just gone through a whole term of electromagnetism so I should know.

    The only way you can get an alternating magnet is by using an inductor with a soft iron core (ie a wire wound around a soft iron core). It's called an electromagnet.

    The problem with this arrangement is, of course, that it costs energy to keep on alternating the magnet from one direction to another, etc. Especially if you need to do it fast.

    By the way, when they talk about "using conventional motors to spin these things" they don't mean that you tie a string to the flywheel and to the motor and start the motor and keep it running until the flywheel is spinning fast enough *grin*. I'd be very surprised if you could get 60'000 rpm out of that!!!

    Daniel
  • One of the points in some of the articles linked in the comments, and the main article, was that increasing the mass doesn't help much. So your portable flywheel will probably be about 100 grams, not 1 kg, but spinning 3 times as fast... and it will hold the same amount of energy (almost).

    Also, it is quite likely that such a flywheel will not be encased in a plastic box. More likely, as was mentioned, would be some kevlar casing. Since the flywheel will be made of carbon fibers rather than metal, if it is torn off its bearings by being dropped, it will (perhaps) disintegrate into thin strands of carbon. These may well be going very, very fast, but they will mostly be stopped by the kevlar coating.

    Of course, even at 100g dropping one of those things on your foot could be unpleasant, but I think that's not applicable to just flywheels...

    Daniel
  • The point of that being...? What? Stop the Earth in its rotation? The Coriolis effect would rip everyone off its surface. Plus it would take some axle to sustain that sort of torque... Daniel
  • He didn't mean that the individual magnets would alternate... if they did, then you'd have an infinite power source and no need for a flywheel.

    He meant arranging magnets around the flywheel in a pattern.
  • good joke.
    However, water has a tendency to flow, and there is considerably more water in the oceans ( and in the atmosphere as vapour ) than could be held in place by damming projects.
    A greater effect is that of global warming melting the ice from the poles. This water will raise the water levels of the oceans, thus slightly increasing the earth's diameter. Using your skater analogy this will actually slow the earths rotation.
  • More importantly, if everyone were to knock down the skyscrapers and then lie down for a nap, the days would go by much quicker.
  • To a certain extend, I do see your point. Alot of what I posted is indeed in the article. Next time I will try to add alot more additional info.

    Perhaps I should have noted some of the interesting research being done on this:

    Physical Limits of Portable Power Storage [mit.edu]

    Batteries of the 21st Century [psu.edu]

    Hybrid Electric Vehicle research [doe.gov]

    In my defense, I do think I pointed out several things that were not obvious (and people were arguing about in the preceeding posts).

    I'll try for more content in the future.

    -Erik

  • Flywheel generators tend to be heavy. If you try to fit one onto your laptop - it would weight so much that it would be unpractical for portability.
  • melting the ice from the poles.

    you mean, "melting the ice from the south pole." the ice at the north pole is floating and if melted it would not change the water level.

  • I have seen this hydrogen idea on paper and in practice. When I was in Paris, at a Science exhibiton there, they had a working prototype, this was over a year ago.

    This is a great idea, but its really just an extension on current petrol (gasoline) engines. It is still using the age-old internal combustion idea.

    The idea behind the flywheel is revolutionary, that is, it isnt based on internal combustion engines at all. Which in itself resolves a fundamental problem, emissions, which are a very serious problem, getting worse, in most countries.

    While I think that the idea for replacing petrol and using hydrogen (much simplified, I know) is great, it still has many problems associated with it. It solves the problem of eventually running out of oil, but we still have many other issues relating to emissions to consider, this is why I think that using a flywheel to power cars is great. I know it is a fair ways off, and there are still many problems to overcome, but this is the way of the future, IMHO.
  • se the wheel's own momentum to power the electromagnets

    you can't convert momentum to energy... both are conserved :)

  • ...and upset he didn't ever follow though on his ideas.

    This might sound like a buncha BS to some of you, but when I was in 6th grade, I remember vividly his explaining a flywheel concept to me. After reading the article, it sounds like the same thing, except my dad's plan had a huge flywheel... to generate large amounts of power. I don't know how they're mounting the motor, but my dad's concept had it mounted on a rail, and a servo system could move it toward the outer edge or toward the center. This would allow a fairly small motor (like their coffee-mug job) to spin a humongous flywheel... by starting at the extreme outer edge. As the flywheel speed comes up, the motor is moved inward, toward the center of the flywheel.

    I guess it goes to show that one should never sit on a good idea, no matter how absurd-sounding it is in 1985.

    (I think the problem there was that he had no idea how to initiate a patent on anything -- who do you trust to help you patent something without having your plans plain-out stolen?)

    I think i'm going to go though my old 6th grade notebooks (yes, I still have some of them) and see if I can find any of his concept drawings. If nothing else, it'll make my old man feel like he knew what he was doing.

    -Steve

    --
  • by Money__ ( 87045 ) on Sunday May 21, 2000 @02:32AM (#1058523)
    If you've ever been on a school playground and seen kids playing on a merry-go-round, you've seen a flywheel. As the kids turn the merry-go-round, it goes faster and faster, then it coasts for a while until it slows down.

    If you put 10 kids around the outside rim of the merry-go-round and try to turn it (called "spinning up") it takes more effort to turn all that weight, but once you get it going up to speed it keeps turning longer. Another approach is to only put 5 kids on and spin it faster. Both of these methods (high weight and high speed) releases energy as it coasts.

    In the case of a flywheel, the middle of the flywheel is attached to a motor that serves both as a motor (to spin up the wheel) and as a generator (to collect the energy being released as it coasts). This time proven method of mechanical energy has a lot of potential because of how little wasted energy there is.

    The 2 methods currenty under research are

    1) Large and slow (buried inside a sub station on an electrical power grid)
    2) Small and fast (portable in an automobile)

    The issue with the small and fast approach is how you fabricate the spinning disk. If a small inacuracy in concentricity produces a "wobble" at 1000 PRM, it gets worse the faster you go. Most current methods employ a computer controled carbon fiber winding machine to collect SPC (Statistical Process Control) data as the wheel is being made and make adjustments "in process". The other area of research is air bearings and aerodynamics. Keeping the heat from friction to a minimum is important because thermal expantion can make the wheel grow a little larger, thus closing the air gap and causing a "touchdown" (this "air==bearing" thing is much like the method employed to "fly" a reader head on a hard drive above the platter).

    As material research continues to explore new materials and computer power allows researchers to model these materials in new ways, there really is very little a fly wheel can't do. At the moment they (the large and slow kind) are being used to replace large battery racks in UPS stations in big buildings and on electrical power grids.
    ___

  • by cybercuzco ( 100904 ) on Sunday May 21, 2000 @05:34AM (#1058524) Homepage Journal
    The best way to avoid this problem, and i believe the way the specify in the article, is not gimballing, which requires extra equipment, complexity and cost, but to simply install another flywheel rotating in the opposite direction, so that the forces created by turning one flywheel are equal and opposite to the forces generated by turning the other flywheel. Yes, this requires two flywheels, but any flywheel powered car would require many flywheels, so this shouldnt be a problem, you just have to install an even number.

  • "...they were almost impossible to reverse-engineer."

    IIRC, that's because whenever someone tried to open one, it blew up violently and killed everyone nearby.
  • I would say this is about as lame as lead acid batteries.. THIS [ballard.com], however, is the shit!

    ----------------------------
  • It would be really cool to develop a mechanism to generate electricity using H20 and the chemical compunds found in air (Nitrogen, Hydrogen, Oxygen, etc.) on the spot.

    This is completely impossible. First of all, your composition of air is way off, there is no hydrogen in air, as free hydrogen. Hydrogen reacts violently with air (remember the hindenburg?) to produce water, which is why we have so much water. In a larger sense, space wise, there is massively much more hydrogen than water or oxygen, mainly because the sun is made of hydrogen, fusion doesnt produce as much oxygen etc, but I digress). Everything in the atmosphere is at a low energy state except for trace amounts of methane due to life, but thats an anomoly and not the rule. It is physically impossible to have an energetic reaction using common atmospheric elements, if it were possible then we would be screwed, because it would very quickly occur, all the energy would be released, and we would be fried to a crisp.

    An Air/Water Cell is the next logical step.

    You are implying then that some catalyist can be found to allow the reaction to proceed, but there has to be a possibl reaction first, and there is no possible reaction between air and water. All a catalyist does is lower the temperature that the reaction occurs at. In a conventional fuel cell, platinum allows hydrogen to be combined with oxygen without a giant fireball. If there were such a high temperature reaction, various above ground nuclear tests would have set it off. In fact, various scientists at the manhattan project were worried about this reaction occuring, i.e that the nitrogen in the air would combine exothermally with the oxygen and produce enough heat to sustain the reaction, and thus making the earth an oven. Lucky for us, it didnt happen, but it also empirically proved that there can be NO reaction between atmospheric constituants that is exothermal.

  • Basically the first half of the wired article linked to above is with the guy in the discover article. If you read the wired article youll not that it mentions USFS was trying to get a deal with GM to manufacture the things and that it fell through,P>
  • Hmm.. seems to me no one has really considered other options in flywheel technology. How 'bout eliminating inertia altogether - Rotate the flywheel in two directions at once. Forget the electric motor and use superconducting magnets in the rotor itself. Before you poopoo this comment check out the guys at
    • http://www.inertialessdrive.co.nz
    who are fiddling with this concept as we speak. They have some pretty awesome applications for this technology already. NO, IM NOT AN EMPLOYEE. (I'm gonna buy the water magnetiser just because it sounds so avante garde)
  • This hasn't much to do with flywheel technology... its with the opening paragraphs of the article.. It mentions that cars are built "backwards". UGH!

    An airfoil is shaped the way it is in order to cause a low pressure airstream on top and a high pressure airstream on the bottom. This causes lift.

    Now... lets apply this to a car... what happens... your car flys away? No.. but close.. it would hover a little more while moving... especially on highways (ie when your going fast)... add rain and your fscked... you would hydrofoil and die. Or come close... the reason cars are tapered at the front is to help push the rest of the car down on the wheels giving it traction. Its an essential compromise of aerodynamics and safety.

    Stupid rant I know.. but it bugged me.



    - Xabbu
  • A bus with some flywheel energy storage was built in the 1970s. The flywheel was steel and ran in vacuum. Worked OK, wasn't worth the trouble after the end of the oil embargo.

    Some early USAF energy weapon work used a "homopolar generator", basically a flywheel spun up to high speed with the field off. The field current was then turned on, and most of the energy in the flywheel came out in a rev or two, producing a big power pulse. I think this technology was actually flown in the 1980s as an experimental system.

    Flywheels for short power-outage ride through have been around since the early days of computers. Lots of mainframes came with motor-generator sets to improve power quality. Some vendors, notably IBM and Cray, liked to convert incoming power to 400Hz, simplifying linear power supply design in the computer itself. Switching power supplies are much less vulnerable to power sags, so we don't see those big MG sets any more. No great loss, either. Still, it was nice to know that no power glitch short of total lights-out could make it though the MG and flywheel.

    Incidentally, you can build flywheels which fully cancel their own gyroscopic action, using pairs of coaxial counter-rotating wheels. Early Sony Walkman units used such a mechanism.

    So flywheel energy storage is a technology that's been around for a while, looking for a killer app. Maybe this time.

  • Is this going to conflict with the flux capacitor on my Linux box?

    You should be okay as long as you keep the bus speed below 88 Mhz.

  • Have you ever seen Carot Top? That lound and lame read headed prop comedian? Then you know what his hair looks like?

    These wheels are made of fiber with much the same consistancy at Carot Tops nappy-doo. When the wheel begins to fail, a few of these strands begin to split off and compromises the airbearing, thus slowing the wheel and causing an imbalance. This further stresses the wheel causing even more strand to split off and slowing the wheel even more. Eventially, there are so many loose strands of fibre that the gap between the wheel and the housing is gone and the wheel grinds to a hault.

    This small "seized up" flywheel poses very little threat for the same reason an internal combustion engine doesn't toss pistons through the hood of your car: Because there are forces acting on the wheel with an apposing force.

    When they fail, they tend to fray (like carot tops hair) and seize up in their housing long before any pieces can cause damage.
    ___

  • Working for one of those industrial behemoths that does a lot of government contracting, I don't think they would be taking flywheel business away from the people that are already doing it. First of all, industrial behemoths like to partner up with someone who knows what they are doing, and perhaps more importantly, they don't own all the patents.
  • Put two of those flywheels spinning in opposite directions. They have to be adjusted to spin at equal speeds. Then you will have eliminated any gyro effects, because the net angular momentum == 0.

    IIRC the article mentioned that satellites would use this configuration, and they could adjust orientations by deliberately changing the balance between the speeds, thus introducing a net angular momentum.

  • by httptech ( 5553 ) on Sunday May 21, 2000 @04:16AM (#1058544) Homepage
    this comment from the article: The wheels are then derated to - that is, run at - 50 percent of maximum speed made you think: "Ooh! I could
    overclock that puppy!"
  • The Baygen torches use a coiled spring and some nice gearing. No need for flywheels. There is an "Instant Torch - never needs batteries" thing you can sweeze for a burst of light that uses the flywheel concept (I have a clear one with coloured plasic parts) but it's pretty cheap. Problem with handheld stuff is that good flywheels are heavy, and there's that annoying gyroscopic effect.

    To anyone in the industry reading these posts, produce a Flywheel UPS suitable for a PC server at no more than 50% more expensive than a decent lead-acid UPS and I'll buy one for home and I'll recommend them as replacements at work the next time a UPS battery fails...

  • by Tony_Cross ( 168832 ) on Saturday May 20, 2000 @10:01PM (#1058557)
    This [britannica.com] is an article from brittanica.com containing the definition and description of the flywheel. Hope this will sort things out for ya. Have fun.


    --------------------------------------------
  • I'd also like to walk through the holes in this post (or feed the troll, you pick).
    1. You always have need to store energy if you're trying to rely on natural sources because they have a cycle, usually 24hours. There are times that it's sunny, windy or raining and times that it isn't.
    2. Storing hydrogen or some other fuel created from air or water can still be considered a battery - or maybe a reservior.
    3. Water is not available everywhere. Some people in the world have to walk 30km each day for drinking water.
    4. Short of using nuclear fission/fusion I'm fairly sure that the flywheels being discussed have a much higher energy density than hydrogen-in-a-bottle. And the conversion two/from electrical energy is more efficient (well, the to part has to be better than an ICE, but maybe modern fuel-cells rival flywheels.)
  • by phandel ( 178702 ) on Saturday May 20, 2000 @10:03PM (#1058561) Journal
    Another page here [8k.com] proposes to use this same technology in a next-generation UPS. They make some pretty bold claims:

    Conventional UPS is mainly a combination of high-maintenance diesel-generators and lead-acid batteries. Other flywheel batteries offer only short-term (most "tens of seconds") ride-through power, during utility line outages; and while the utility or on-site generator supplies power, they constantly consume typically kilowatts while idling. That's over 1000x more losses than RPM's Flywheel Battery; which runs far cooler, will have far longer service life, negligible self-discharge, far higher reliability, far lower life-cycle cost, no wear-out, and no maintenance!

    There are quite a few additional links at the bottom of that page.
  • Would two flywheels with opposite rotational directions fixed to the same object cancel the effects of each other out?
    On the outside of the system, sure, but inside they'd be trying to tear themselves apart.

    Putting flywheels in moving objects is not the major thrust of the article (I read it in the print version of Wired ages ago, even referenced it in a /. discussion) - simply using a sensible, even retro, technology like this in any application is the point. There's reference to using them as batteries / UPSes for huge installations - factories, power plants. They're very effecient, low maintenance, large batteries. If you're just worried about whether or not they could be used in your car, you're missing the point.

  • The lead-acid battery is on the way out. It doesn't work all that well, takes up a lot of room, weighs a ton, and royally screws the environment.

    I really dig the advanced flywheel and carbon nanotube stuff. But wouldn't it be even better if no batteries were necesary? We have lots and lots of water and we have lots and lots of air. It would be really cool to develop a mechanism to generate electricity using H20 and the chemical compunds found in air (Nitrogen, Hydrogen, Oxygen, etc.) on the spot. Fuel cells are becoming better and better. An Air/Water Cell is the next logical step.

    A machine which converted water and air to electricity sounds much like the goal of alchemy. It is a pipe dream. Yes. But e- wants to be free.

    Once external energy becomes freely available to everyone anywhere, all manners of political change would follow, not least which would be more free software.
  • by Spoing ( 152917 ) on Sunday May 21, 2000 @04:29AM (#1058569) Homepage

    A laptop with a charged-up flywheel in it might exhibit some interesting gyroscopic effects... you could pick it up, but wouldn't be able to turn it upside down?

    Hell, put little feet on it, have it purr, and you'll have a replacement for a cat!

  • > Ni-Cads have the memory problem.

    Ooooooh no they don't. Well, not in any way that's relevant for pretty much anyone's purposes.

    I direct your attention here [repairfaq.org] and here [repairfaq.org] for a detailed explanation.

    In brief, what most people call "memory effect" is really a combination of voltage depression resulting from the overcharge performed by all consumer battery chargers, and natural cell aging. Voltage depression does not greatly reduce cell capacity, but it does change the shape of the cell discharge curve - the cell's voltage drops abnormally early in the discharge cycle from the normal 1.2 volts to 1.05 volts or so, which may cause some devices to believe the cell is flat, because a normal NiCd IS very nearly flat when its terminal voltage has fallen this far. A voltage depresed cell, however, can actually deliver about the same amount of energy as it ordinarily would.

    Genuine memory effect is very, VERY seldom seen, only occurs in sintered plate NiCd cells, and is in fact CURED by overcharging! Nickel metal hydride batteries are utterly immune to genuine memory effect, although they, too, can suffer from voltage depression.

  • Comment removed based on user account deletion
  • My physics professor from Ukraine once told us a story from his years spent in the Army. They had a general coming to visit and the generals car was a ZIM - it is sort of a JFK's Cadillac shape and size Russian made car - very heavy and bullet proof (I think those are almost rocket proof) anyway, there was a gyroscope in that car, they have it on purpose so that the car will never tilt over even in case of an accident or an explostion. So the driver of the car showed the soldiers a trick: he asked the men to lift the car from one side so that it would only stay on its two side tires and not on all 4 tires. They lifted the car and he turned the gyroscope on. The car just was standing there on two tires and it did not move at all. It was hanging in the air with only 2 points on the ground. Then he slowed down the gyroscope a little and the car started falling down very very slowly and at some point it just touched the ground lightly with the other 4 tires.

    That's why my physics professor decided to continue his education in physics after the army and became a professor - he was impressed with the effects of gyroscope, I think I also would be impressed.

    Back to our story, I wonder if it would be possible to use the fly wheel as a gyroscope to keep a car in the air? I lived in Montreal (Canada) for 2 years and the Local Hydro there was working on the electric cars powered by fly wheels and hydrogen cells. They also invented an engine that goes into a tire and each tire became an engine, but the project stopped due to some resistence of SHELL and Oil production companies.
  • but those results have not been revealed because of "commercial reasons." (Don't these people ever learn? You're not going to make a cent unless your process stands up to scientific review!)
    Back in the real world (non-Open Source, non-Software, there is such a place), corporations aren't always nice communities of people that will respond to your emails and modify their software distributions accordingly (in fact, there are actually some corporations that don't sell software). Many corporations in this so-called 'Real World' are greedy, capitalistic scum-suckers that care about only making the most money, instead of ethics. (You can relate those to Microsoft). Now, when you simply reveal the blueprints (source code) to the scientific community without either an NDA or a patent (real world equivalent of the GPL), these greedy, evil corporations (read: Microsoft-esque) will steal/ borrow/ use your new product in theirs. Now, you're not going to spend the time to patent something that doesn't work, simply stated, so your product needs to go through scientific review before you patent it. The only other option is going to be an NDA, or (more likely), an in-house team of scientists. Now, if they're not revealing it for 'commercial reasons', then they're probably planning to (gasp) make a profit on it. Now, that might sound like an absurd concept to you, but there are companies out there that make a profit. Redhat, Debian, etc.. make profits from selling their distributions, so profits aren't all bad. Look up. That banner ad is a profit for Andover. People like profits. Not everything is Open Source (at least, outside of the realm of software). Don't complain. They're just trying to remain competitive.

    BTW, 'you' in that post refered to the Slashdot community at large, not just you.
    BTW, the last 'you' in that message refered to the you, not the Slashdot community at large.
    BTW, the last 'you' in that message refered to the you, not the Slashdot community at large.
    ...
  • Is this going to conflict with the flux capacitor on my Linux box?

    Just wondering...

  • Actually, there's another method for storing and retrieving energy from a flywheel based on embedding magnets in the flywheel and keeping it levitated in a vacuum. You use the rotating magnets to drive an electric motor and charge them up by reversing the polarity. Since there's no mechanical attachment to an engine and next to no friction, you can theoretically keep the momentum stored in the flywheel indefinitely. I remember reading about a guy who had come up with an automobile engine based on this design in Discover magazine about a few years ago. Unfortunately, the guy was a bit of a patriotic zealot and refused to sell the design to anybody but American auto manufacturers who had only a passing interest in making it into a backup for a hybrid engine design. The Japanese were biting at the bit to buy his technology for use in non-hybrid applications, but he refused to sell. A shame. People all over the world might be using his engine design now if he hadn't been so against letting a foreign company use it.
  • You're not going to make a cent unless your process stands up to scientific review!)

    With due respect to your otherwise insightful post, I must disagree with this assertion: while affirmative scientific review may gain you credibility, it does not affect profits. What determines whether you're going to make a cent is (a) whether you can sell it, and (b) whether it works. Edison sold an awful lot of lightbulbs before photon emission from Bohr shell level transitions was understood.

    --

  • Coriolis Effect is not directly related to gyroscopic properties.

    Coriolis Effect (not force) simply describes the behavior of objectsin freefall when the reference point is fixed to a spinning surface.

    Say.. you were on one of those sci-fi 'spinning' space stations, standing on the inside of a ring, (you know... simulated gravity). It feels like gravity.. but if you were to jump up in the air, you would find the station would spin out from under your feet, and you would not land in the same place you jumped from. If you went to pour a drink cocktail-style, you'd find you have to angle things differently, as anything dropped will follow an arc away from the direction of spin, not straight down.

    And gyroscopic forces simply need to be balanced. If you had two wheels on a typical demonstration gyroscope, spinning in opposite directions at the same rate, the gyroscopic effects completely disappear.
  • An old sci-fi book I found by accident... I can't even remember the author (though I did recognize it) or the name. (very useful information, I know..)
    One of the concepts in this book, however, was the idea of using a (sci-fi) kerr-newman black hole as an extremely massive flywheel. The (sci-fi) theory is that a kerr-neuman black hole is basically a very tiny black hole (event horizon of perhaps 200 meters or so.. something human manageable) that is electrically charged. It is also spinning, rapidly. Remember, a black hole this size STILL weighs an unimaginable ammount.
    So they built these huge shielding chambers, they'd put a black hole in side it (it's got an electric charge.. they can move them around using this...), and it sits in there and spins. Fast. By feeding energy into the chamber, they can spin it faster, and by tapping the Electric field (generator?) they can take power, causing it to slow. The deal was, though, that one of these jobs, even without replenishing hte power, could, once charged (and they were naturally charged when found) could hold enough energy to power cities (or planets) for years.
  • by mindstrm ( 20013 ) on Sunday May 21, 2000 @08:59AM (#1058601)
    Unfortunately, it's not criminal... nobody who discovers something is obliged to share it.
    If your tax dolars fund the military, who funds research, who develops cold fusion for powering weapons (like subs and planes).. they aren't obliged to share it with you. Nope. Not at all. It would be against 'national security' to do so.

    In the corporate world, this is what patents were supposed to be about... so people would be encouraged to share.

  • Is anyone else concerned by this? First off, the gyroscopic effects already mentioned would be real, and prominent. Richard Feynman used to put a flywheel in a suitcase and give it to a bellhop as a practical joke. (The suitcase would almost fly out of the poor sap's hand at the first corner.)

    Secondly, angular momentum is conserved. If you get enough flywheels spinning with the proper orientation, you could (in theory) have a serious effect on the Earth's rotation. They'd have to be spinning pretty bloody fast and be aligned just right, but it's possible. What happens when the factory ships a truckload of these? I hope they design two models, with spins oriented anti-parallel...
  • by A nonymous Coward ( 7548 ) on Saturday May 20, 2000 @10:33PM (#1058603)
    My high school chemistry teacher was a former naval officer. As a midshipman in the 1920s, he and some buddies installed a big gyroscope in a suitcase, spun it up on the sidewalk in front of the hotel, walked straight in to the front desk, set it down, booked a room, and laughed their middie asses off when the poor bellhop picked it up and tried to turn around.

    --
  • by Anonymous Coward on Saturday May 20, 2000 @10:34PM (#1058604)
    The research has gone pretty far in the last few years. I worked on producing carbon nanotubes for my undergraduate thesis in physics in 1994-1995, when metal doping of the carbon electrodes was first described for generating single-wall nanotubes (SWNT's). Since then, fullerene research has pretty much continued at a feverish rate, with numerous papers published each year describing improved methodology, fullerene properties, and new practical applications. These have for the most part born out the incredible theoretical predictions about their unique properties, including astronomical length to width ratio, superb tensile strength and geometry-dependent conductivity. Like the laser, fullerenes hold the promise of being a solution looking for a problem.

    In answer to the question specifically on carbon nanotubes, there has been a lot of experimentation done on them. Carbon nanotubes come in a variety of geometries that can be thought of conceptually as rolling chicken wire (a hexagonal array) up with varying amounts of stagger or offset. They can range in conductivity from metallic to semiconducting, depending on this geometry (Science, 288(5465):494-7). They have been used as tips for atomic force microscopes (PNAS, 97(8):3809-13). Tensile strength studies have found individual nanotubes with a Young's modulus E of nearly 1 TPa, or 1000 GPa (Science, 287(5453):637-40). Various other electromechanical applications like field emission effect (Science, 283(5401):512-4) have been dreamed up.

    Not being in the field any longer, I can't make any predictions about timescales of the integration of carbon nanotubes into new technologies. However, you can usually tell that a material is no longer just a laboratory curiosity when the major chemical distributors start selling it, like Sigma-Aldrich [sigma-aldrich.com]. The fact is that carbon nanotube production is incredibly cheap and easy (doable by a fresh undergrad student, yours truly...). It is the purification of the desired nanotube type from the mishmash of soot you obtain from the arc that is the real challenge.

    Ryan.

  • Ummm... I'm no chem major, but H2O is already a low-energy molecule, i.e. you can't react water with [something in the] air to produce an exothermic reaction, because it doesn't have any energy to release.

    Now, if you're talking about electrolyzing the water first (separating it into H2 and O2), and then reacting the hydrogen and oxygen together, then you have something that works. Hydrogen power.

    The idea being, you can electrolyze water in a large, stationary facility, and load up vehicles with hydrogen as fuel. In theory, the vehicles burn the H2 + O2 from the air, and give off nothing more than water vapor as exhaust. In practice, N2 in the air screws things up royally (makes nitrous oxides in the exhaust, IIRC), and storing hydrogen is a whole issue unto itself (since it tends to be explosive and all...)

    Still, it's a cool idea, and it's being worked on. I believe H2 engines are supposed to be quite strong, even compared to gasoline ones. At least the H2-O2 reaction is *incredibly* powerful.

The Tao is like a glob pattern: used but never used up. It is like the extern void: filled with infinite possibilities.

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