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Flywheel Energy Storage: Steel Yourself For Carbon
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.
Guys - think of it like the integrators used by Vannevar Bush in his Differential Analyzer 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...
Reason is the Path to God - Anon
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).
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.r .html
Check out http://www.amsat.org/ and
http://myweb.magicnet.net/~phase3d/newpics/sola
(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.
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).
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
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!
"How perfectly Goddamn delightful it all is, to be sure" Charles Crumb
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.
I am having a hard time deciding which is cooler, flywheels or thermophotovoltaic generators. I guess I will just have to hope for a tpv/flywheel electric hybrid car to be made. That would seriously kick ass.
"Remember, there never were pineapple-almond cookies here."
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.
I don't care if it's 90,000 hectares. That lake was not my doing.
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
There are always four sides to every story: your side, their side, the truth, and what really happened.
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...)
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?
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.
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.
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I would say this is about as lame as lead acid batteries.. THIS, however, is the shit!
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Esobofh - Currently drinking fresh mango juice.
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.
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.
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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.
Jack Valenti and the MPAA are to technology as the Boston strangler is to the woman home alone
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.
Escher was the first MC and Giger invented the HR department.
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!"
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...
This is an article from brittanica.com containing the definition and description of the flywheel. Hope this will sort things out for ya. Have fun.
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Another page here 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.
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.
--
He lives in a world where those who do not run the client software of the omnipresent meme are unacceptable.
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!
A firewall can not protect you from yourself. Turn off what you do not need. Do not use the firewall to do your work.
Ooooooh no they don't. Well, not in any way that's relevant for pretty much anyone's purposes.
I direct your attention here and here 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.
Just wondering...
Got Rhinos?
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.
If it's for-profit but free, you're not the customer -- you're the product (e.g., the Slashdot Beta's "audience").
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.
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...
- W. Blaine Dowler
http://www.bureau42.com
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.
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Infuriate left and right