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Flywheel UPS

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  • by Anonymous Coward
    These things have other problems not mentioned here. Most severe is the the way they deliver power; as the wheel spins down the voltage they deliver drops. Anyone counting on these things to run for a long time better way over-purchase.

  • by Anonymous Coward
    NASA Glenn Research Center was working on flywheel technology to use in lieu of the batteries on the ISS. I guess the idea is that batteries have a much shorter usable life span before they need to be replaced and transporting replacements becomes a burden. Unfortunately the project got eliminated in this year's budget for the center. I guess somebody had stock in Energizer. :-) I will remain anonymous since the last person who spoke out about the project cut in our local newspaper was fired. :-/
  • Actually a lead flywheel would destroy itself within a few seconds of spinning at those high speeds...

    Duh. Lead is soft. You encase the lead in a thin shell of harder metal. Next problem?

  • by Anonymous Coward
    Soon it will be discovered that if the device in mounted on 4 bricks, you can remove the two bricks on one side, and the device will float above ground because of the all the energy stored in angular momentum!

    How cool.

    This will be repeated at every lunch break at the company, for the amazement of everyone. After the loose side of the box has gently fallen on the ground, 10 strong employees will put back the 850 lbs Flywheel Module on 4 bricks for tomorrow's show.

    Unfortunately, this puts an enormous stress on the device, and it will break after a few show. MTBF of 100,000 Hours? Not in "normal conditions"!

  • If you put it underground, it doesn't take up any space in your equipment room.

    Not much of a problem, is it?

    Forget Napster. Why not really break the law?

  • How many would need to? If you're building a hosting facility from the ground up, this is something to consider.

    - A.P.

    Forget Napster. Why not really break the law?

  • Why not? That's the type of customer they want buying these things. Those racks of storage batteries have to be replaced sometime. They are pitching this as an alternative that doesn't have to be replaced every few years.

  • The company took great pains to discuss flywheel safety. [] As you know, there is a pretty big danger of this massive disk spinning around at high speeds and suddenly breaking apart due to physical forces and spreading shrapnel around everywhere.

    I think it is bound to happen as these devices become more popular, but it probably will be fairly unusual.

    The only reason I mention this is that I am "somewhat" amused by the idea that a new technology is creating a new way of dying as well. Perhaps there will be a day where the casual newspaper reader will come across the headline "Two engineers killed in flywheel discharge in Coeur d'Alene" and not think it out of the ordinary.

    This also goes along with the idea that mother nature will invent all sorta of gruesome ways of dying to deal with the fact that we keep on solving conventional ways of dying as time goes on. In the end, I suspect that she will be forced to rely on spontaneous human combustion as the catch-all unsolvable/incurable death once science has cured disease and engineers have prevented most accidents. Until then, expect that flywheel discharge will occasionally send a hapless individual into their next life.
  • Chagrin babbles:
    Actually, the flywheel module would be buried. Try visiting the actual link and you'll see that is what is done.
    Building an entire structure just to house the flywheel is quite rediculous.
    Suggestion: Engage brain before shooting off mouth.

    Supporting Argument: This thread is about alternatives to burying flywheels; places where burying isn't a possibility. You try paying attention to the discussion before admonishing others to re-read something.

    Resolution: The polite thing would be for you to apologize - are you up to that?

  • Flywheel Module 36" high x 27" diameter Size--Electronics Module 32" high x 18" wide x 12" deep
    Access. While the flywheel module is fairly small presumably folks will want access to it (inspections, replacement, etc.)

    Thus I imagine the stucture would resemble a block with a hallway built into it with a right-angle and some good solid doors. Presumably the walls would be free-standing as so to minimize any transmitted impact.

    Figuring six inches for the walls, 4-feet of sand and allowing some extra for supports & conduits it should all fit within a cube 15" on a side.

  • How many companies do you know of that can go digging around to make a huge hole to fit 1000 lbs of metal?
    First off 1000 lbs of metal isn't that much, it's equivalent to about 5 sysadmins or 4 coders (values may vary depending on your OS & languages.)

    The space required to store a flywheel of this size would be about the same as two parking spots. Seriously. An inner concrete wall, an outer concrete wall and a lot of sand in-between. Figure 15' on a side max, two stories high.

    One can find that sort of space in any building. Heck, that fits in the machine-rooms of many office towers alongside the water-pumps and transformer; the only issue would be the static load and inertia problems on upper floors.

    Furthermore this is about the same volume many mid-size backup generators take when one figures in clearence, muffler, etc. Lots of new tech-buildings are built with platforms in back for these & there's usually a few decks left empty for expansion.

    If one didn't want the flywheel inside the building proper (though it would be quite safe) there's always the dead-corner in a local parking structure. Heck, this could create a whole new market for the bottom of elevator-shafts - tuck the flywheels down there.

  • see, for example, The Bunker [], which was built during the 70's and 80's, and uses rotational inertia for 'power smoothing'. Their Tech Info [] pages are an interesting read, and there's a nice photo of their 'Power Buffers' [], too. This might be a bit overkill to run in your basement, though.
  • We're going back to moving parts here. At least a battery-based UPS would have minimal moving parts, probably a few relays for overcurrent protection and a transformer with a moving center tap to regulate voltage in the traditional UPS. With a big moving part like a flywheel, we have got a fair bit of noise here. The specs [] say less than 55 dB, which is roughly the amount of noise produced by a typical conversation. And the efficiency of the system is somewhat pathetic. The system can store up to 2 kWh of energy. It takes three hours for it to store up this much energy with an input power of 2.5 kW, meaning you input 7.5 kWh of energy to it. The remaining 5.5 kWh of energy was wasted. Wasting so much energy is not the way to be environmentally friendly! True, a traditional battery based UPS would cause environmental pollution when you tried to dispose of it, but 5.5 kWh of wasted energy every time you had to recharge the thing would likely produce even more pollution in total. True, the system may have many potential advantages, especially for use in harsh environments that would ruin most battery-based systems, but to call it environmentally friendly is an absolutely laughable claim. It is probably even less environmentally friendly than the average battery UPS, it just produces a different kind of pollution (by wasting much of the energy provided to it from the power generation system). And one more thing: the thing is immense, it weighs a total of 1050 lbs!

  • Might as well coat the flywheel with oxide, put a bunch of R/W heads around it and get some use out of the thing as rotating memory while the power is on. Wish I could post some pictures of some drum memory units from the 50's - they are BIG.

  • I did some contract work for a place that used a flywheel on their old CDC mainframe. It wasn't just for emergencies, it was the power-filter too. One little spike in the AC doesn't tweak a flywheel much, so being a UPS was only part of the use.
  • by Syberghost (10557)
    EMC uses this in their Internet Solutions Group center. If you want to find out about how it works in action, or see a successful data center using it, call your EMC rep.

    It may be huge and heavy, but it's a damn sight easier to manage than a room full of lead-acid batteries, and you don't have to refill it every five years or contact the EPA every time you do any work on it.

    Makes cooler noises, too. :-)

  • The personal computer version ought to fit into a 5.25" drive bay and double as a CD-ROM drive. Most modern CD-ROM drives seem to build enough angular momentum to run a refrigirator for a couple of hours anyway.

    But then again, a friend of mine was nearly decapitated by a Toshiba X32 drive with a premature ejection problem.
  • Yeah, Wired covered this whole story about 6 months ago. One solution was to bury the things underground, with just the top access area poking out. That way if they do break, at least nobody gets hit.

    But wait! Bury enough of these things and we'll eventually have enough angular momentum to shift the Earth's axis! Think, man! This will kill us all!

    Hey, maybe this is the reason Uranus is rolling around on its side...

  • But then again, a friend of mine was nearly decapitated by a Toshiba X32 drive with a premature ejection problem.

    Perhaps one of these [] can help with your friend's problem.

  • Actually, my father once told me that some passenger busses in europe used flywheels for movement. Don't know too much about the details, a few google searches should turn up something.

  • by mlc (16290)
    Only problem is, from the website, it's too big to replace the conventional UPS that most places have. It has to be put underground, and it stores 2kWh of energy.
    // mlc, user 16290
  • On a larger scale, this could solve the current energy problems. The problem isn't one of energy presources so much as energy delivery. If flywheels could be charged (like batteries, but with much less loss in the charging process) during off-peak hours, they could be used to cover overextensions at peak hours [].

    I read an article on /. around the beginning of the year about power companies burying large flywheels underground to cover brownouts and short-duration blackouts. This could be a great growth industry.

    Kevin Fox
  • What do you define as living near? Unless you are sleeping with this next to you.... you have little to worry about.

    After all, we have thousand ton trains hurtling around with FAR more kinetic energy than this flywheel would ever have...
  • by mindstrm (20013) on Saturday May 26, 2001 @01:34AM (#197370)
    First, regarding the Gyroscope question.
    A single flywheel would act as a gyroscope, yes.
    Two equally massive flywheels spinning in opposite directions but at the same rate would effectively cancel the effect though. (This has been tried with bicycles to prove that balancing a bike is not actually due to gyroscopic effects).

    I'm no scientist, but it seems to me that flywheels, no matter what, will be more efficient the larger they are, given that friction is the only thing that will cause the flywheel to lose energy... and friction is a function of the surface area of the wheel.... wheras the amount of energy stored is based on the mass... and as surface area is a square function, wheras mass is cubic, you end up with diminishing returns as things get smaller.

    Same sort of thing as why a flea can jump 50x it's own height (or whatever the number is) but a human can't... as muscle strength is proportional to cross sectional area of the muscle, but mass is proportional to volume....

    Also, one issue is the possibility of explosion in any mobile device. The fact that a chemical cell can only discharge so fast can also be viewed as a safety feature when we're talking about consumer devices. A nano-flywheel-cell or something in a phone might have a propensity to explode violently should something disturb it.

    Also, regarding some sci-fi.. I *wish* I could remember the author or title.. but I recall reading some sci-fi from the 50's or 60's that dealt partially with using some small-ish black-holes (they called them kerr-newman black holes ,or kernels for short, if it rings a bell). The idea was these things were both spinning at a great velocity, and electrically charged (so they could be magnetically manipulted) so they shielded them, moved them around, and used them as humungous flywheels for storing and retrieving energy.

  • I was visiting one of Above.Net's hosting facilities [] a few weeks ago, as my employer haqs decided to use them as a hosting facility. They use a flywheel storage/conditioning system, and have for some time now. Above Surface. And not all that big. . . Pretty slick, plus they have redundancy. As I recall, the flywheel/UPS/powerconditioner is a German product, sorry, no specs on the manufaturer. . .
  • If you use just one flywheel mounted vertically - make sure you spin it down before you park the car - otherwise your car will roll over onto its back like a turtle in the next 12 hours. Ok, it probably won't have sufficient mass/velocity to actually make this happen but the idea is nice :-)

  • Hmmm, a quick search on Google turns up plenty of hits for this stuff - it's not THAT new. [] [] [] eel/papers/powertrades-oct98/ [] - a NASA study from 1998

    All with URLs displayed, for you who fear Somehow, this doesn't look like that new of a technology. (And besides, I thought a REGULAR UPS was heavy!)
  • Reading between the lines of their web site, I believe they intend these to be useful in places where the cost of replacing batteries is significant. Even if the batteries are only a couple hundred dollars, getting a crew to the location with the batteries could cost many times more.

    I have supported sites where onsite maintanence cost $7,000 per incident (and just wasn't possible for parts of the year). Sure makes you think twice before typing each remote command. :-)

    Maybe these things will be common someday, not soon. Railroad crossing lights in the US used to be powered by large buried batteries. Periodicly trains would come by, hoist out the old one and put in a new one then haul the old one back for recharging. Maybe 40 years from now using chemical batteries in UPSs will seem just as silly.
  • Heck, this could create a whole new market for the bottom of elevator-shafts - tuck the flywheels down there.

    What if the elevator fell on the flywheel?

    I think you'd have a chain reaction on your hands...
  • Course it's not much good if the outage takes down your ISP. (Like happen to my Uni this week)
  • IBM Lexington mega facility had that for years. Basically it's a big motor generator set. It also makes for one hell of a surge protector. The motor laughs at anything less than a direct lightning strike. For blackouts, The flywheel keeps going long enough to crank up the Diesel.
  • Looking at the specs [], I read that this thing weighs over a thousand pounds and takes a full two hours to spin up.

    Reminds me of those old MFM Seagates...

    Seriously - does anyone really want something that weighs half a ton and spins so damned fast that it'll drive a generator for three hours sitting next to them?

  • digging around to make a huge hole to fit 1000 lbs of metal?

    How big a disc do you need if you use depleated uranium? Also you could mount the thing with the disc vertical. So it simply becomes a thick wall.
  • High capacity deep-cycle lead acid batteries trample all over those figures. A quality lead acid 12V battery that can deliver 25 amps (300 watts) for more than seven straight hours (more than 175Ah, at that discharge rate) costs maybe $US400, and weighs maybe 60 kilos.

    The problem is that the batteries need maintaining. Also if the idea of the UPS is to supply power whilst a generator is brought on line then being able to run for 7 hours isn't really relevant.
  • As you know, there is a pretty big danger of this massive disk spinning around at high speeds and suddenly breaking apart due to physical forces and spreading shrapnel around everywhere.

    I've only heard of this happening once, due to a manufacturing defect. Loads of people sit very close to large disks spinning at high speed every day. Parts of jet engines do not rain out of the sky constantly though.
  • The moment of inertia is proportional to mass, but also greater when mass is distributed farther away from the centre of motion, (varying as r^2), so having a physically large mass is one way of getting away with lower spinning speeds

    Thus you want a wheel rather than a simple disk. With most of the mass on the rim.
  • How are these normally installed--inline or failover?

    The reason I ask is that if they're implemented inline, they might be able to kinda act as a proxy for the A/C. That could be important because apparently Van Eck/Tempest phreaking has become somewhat passe' in fedland. Instead it's (apparently) possible to observe what a computer is doing by reading the power lines. No, I don't have references; it's really a he-said-she-said thing.

    But what I'm wondering is if you could use a flywheel to clean and sterilize your A/C current usage.
  • My boss was recently reminiscing about something that sounded exactly the same. The computer took an entire three story building however and was freon cooled, so such a thing was a necessity. It was also hooked up to 500 horsepower generator, so it wasn't really environmentally friendly either.

    But it did have a really fast punchcard reader. :)
  • Actually one of the companies mentioned above has a mobile product, using two opposed flywheels: []

    Interesting that the currently available systems seem mainly aimed at high-drain short duration applications - would they be less efficient at much lighter loads (e.g. as primary power source)?

  • That's likely about the same amount as your desktop computer's fan. Of course your computer's fan isn't buried in the ground, but 55db isn't loud by any means. Most people's comfortable easy listening level on their radio is say around 65db @ 1 Meter.
  • by seanw (45548)
    this will be PERFECT for windows users, as they're barely a step up from hamsters anyway. oh wait, what kind of wheel?
  • > No, he dont have to go in a strait line, he can move any direction, but he must keep the briefcases in the same direction.

    Thus, if he takes a right angle corner, he'll have to walk in such a way to keep one suitcase before him, and the other one behind (rather than the usual position of one to the left, and one to the right). Not only will this be very uncomfortable (especially if heavy), but it will also look suspicious as hell...

  • > Watch as the bellhop rounds a corner and the suitcases jump out of his hands!

    Wouldn't the Bellhop notice that the suitcases are slightly trembling, as soon as he picks them up (a little bit like the feel of a holding a spinning HD in your hands)? And what about that whirring sound?

    And, as the prankster himself has to walk in a straight line with the suitcases once they're active, wouldn't this force him to do the spinning up part in a straight line before the hotel lobby (and thus probably in plain view)?

  • I know that Comnet corp. did this a long time ago in their offices in Washington, D.C. Their flywheel was able to power their mainframes for just a few minutes though, to give them time to turn on a backup diesel generator.

  • Sigh.
    Read the specs.
    It weighs 1050 pounds.

    "Weight--Flywheel Module
    850 lbs

    Weight--Electronics Module
    200 lbs"

  • >>BTW: If you built portable flywheel "batteries", would they act like gyroscopes?

    If my understanding of physics is correct, then a simple flywheel would *have* to act like a gyroscope. Maybe two wheels spinning in opposite directions or something.

  • Saw a similar device at the Allen-Bradley offices in Cleveland. Big electrical motor drove a flywheel and generator that powered their mainframes (this was about 1983).

    Probably wasn't very efficient - but as well as the UPS function, the inertial damping was extremely effective at eliminating power spikes.
  • Flywheels would solve almost all of those problems. I'm not an expert, but from what I understand, the biggest problem is developing materials that can withstand rotating the the enormous velocities requires. It sounds like fuel cells will come out sooner.

    This is more of a problem with vehicles, where the flywheel is subject to tradeoffs between operating at a very high speed to store a lot of energy, practical limits on flywheel size and weight, and the weight of the armor around the flywheel needed to prevent potentally deadly chunks from flying loose if it does disintegrate. I understand they're trying to develop graphite composite flywheels for vehicles.

    None of this has to be a huge problem for a fixed installation, however. You could make it massive and fairly fast and put three feet of reinforced concrete around it without too much trouble.
  • Well, if you had the flywheel spinning fast enough to hold a useful amount of energy, it would probably have enough rotational inertia to make steering nearly impossible

    With the flywheel hub/axle mounted vertically it would only torque the car when power was being added to or removed from it. Two counterrotating flywheels would cancel even this effect, and the engine mounts would mainly have to deal with changes in the road's incine because the gyroscopic effects would try to keep the car from leaning or pitching up and down.

    Mounted sideways, though, those effects would oppose turns and aim the car in unexpected directions when they were attempted.

    On the third hand, I'm not sure any of that would apply enough force to matter.

  • The Ampex HS-100 analog disk recorder (used to provide the original slow/stop motion instant replay in TV sports events, back in the 1960s) was a rather dangerous device. It used a heavy 18-inch platter to record up to 30 seconds of video at (I forget) either 1800 or 3600 RPM. Which had an unfortunate tendency to suddenly leave its enclosure at an extremely high speed.

    Evidently no human injuries were reported, but a few walls were casualties.

  • Back in the 1970s when I was working aboard the Hughes Glomar Explorer ( tm) (hunting manganese nodules; wink wink) the control system for the heavy lift mechanism was based on 16vdc CMOS technology. The voltage spikes aboard a 50,000 ton ship with 4480 volt mains could be truly extraordinary and to eliminate these spikes we had a flywheel-type UPS.

    This UPS wasn't really used as a UPS because a loss of power would affect more than just the control system (the hydraulic systems ran off of pumps which were operated by electric motors) but it sure ironed out the spikes nicely.
  • UPS trucks are brown. Not FedEx trucks.
  • The first thing the casual newspaper would think is "where in the hell is "Core da lane" :)
  • Ya know you should look up the word
    hyperbole (h-pûrb-l) n.

    Now some quick calulations

    I found a reference for the energy release of good ole TNT or trinitrotoluene is around 4680 joules/gram.

    Lets see 1 Jjoule is 1 watt*sec therefore

    2 Kw*H ~ 1.5 Kilo of pure TNT.

    I think that could destroy a masonary wall quite nicely. The time period the energy is release is very important.

    BTW, Just cross checked the above calculation with a cool site
  • If you removed the bricks on one side then you would get a (huge )torque induced at an 90 angle or horizonal in this case. A top can balance horizonally and seem to defy gravity only as long as it can rotate itself along the vertical axis. Stop it and falls immediately.

    If you attempted what you suggest your flywheel would start spinning uncontrolled and would reduce 10 city blocks to rumble and hence why they bury this thing.
  • Close... KE = .5 m*v^2 Too much relativity in a nonrealistic world...
  • Heh, that was my first thought too. Flywheels WOULD make a lot of sense for delivery trucks though, with their constant stops. Flywheel brakes transfer energy to a flywheel to stop the vehicle, instead of just creating waste heat through friction. The energy in the spinning flywheel can then be used to accelerate again.
  • Kinetic energy weapon. I read their safety page and I'm still nervous. Their odds of one in a million for failure modes still seem rather high to me.

    Another thing that springs to mind is reference to flywheels as energy storage in science fiction. Harry Harrison uses flywheels as a technological prop for powering motorcycles/monocycles in his Stainless Steel Rat series. You charge (spin up) the flywheel at night and use the stored kinetic energy by day. Use regenerative braking to get back some energy for "free" while you ride. And you get the gyroscope effect to keep the bike upright. Very quiet, simple and clean. Neat idea.

  • by shaper (88544) on Friday May 25, 2001 @09:14PM (#197406) Homepage

    Does it also work for FedEX vehicles? ... So that's how those big brown trucks full of packages get around!

    Oh, the horror :-) Sorry if this is off-topic, but the image that just sprang to mind is so compelling ...

    Right now I'm seeing scores of marketeers at FedEx and UPS clutching there hearts over that comment. I don't know which group would be more apoplectic, the FedEx guys for misidentifying their mortal enemy (UPS)'s trucks as FedEx delivery vehicles or UPS for hanging FedEx's our-name-is-a-verb on that oh so distinctive brown truck. You just wiped out two different companies' marketing droids with one swift blow!

  • Woah.. with that nifty thing, rig up a pedal powered system to pick up where the ups stops-- for those Rolling blackouts you just get your employees to move from their desks to their designated stationary bicycle.

    Who'da thunk it? -- an employee fitness program and disaster contingency program all in one!

  • by Above (100351)
    One of the leading companies in this market: Piller [], has a lot of very useful information on their web site.
  • "One in a million odds happen eight times a day in New York." -- Penn Jilette
  • One of the biggest potential uses for flywheel technology is for satelites. At the moment the lifetime of a sat is (amongst other factors) determined by the cycle limit of its batteries. Since sat batteries are cycled EVERY day as they go into and out of the sun, they take quite a hit, and they are obviously quite tricky to replace.

    If you were to use high speed vacuum sealed flywheels on magnetic bearings then the friction is obviously very low, and the limit on the lifetime of the system is a material limit. Currently a fair amount of development cash is beiong spent on making fibre materials to use in flywheels which don't fail catastrophically, have predictable and high failure stresses and low creep.

    There was an article [] about this in Wired a few months back.

  • why? Stick it in a vacuum, and put it on magnetic bearings: voila - almmost zero drag therefore no energy loss.

  • Most modern CD-ROM drives seem to build enough angular momentum to run a refrigirator for a couple of hours anyway.

    bollocks. Rotational energy, not angular momentum is the name of the game. 1/2 MJw^2 with a 40X drive getting up to about 900 rads/s, the mass of a CD at about 20 grams, and the polar second moment of area of a circle being piR^4/4 then the rotational energy is less than a Joule.

  • which is how the hubble aligns itself.

  • In the unlikely event of failure, our composite rim is designed to delaminate in a safe and controllable manner.

    I guess 'explode into shreds' didn't score well with the managers...

  • Unfortunately, the average person can only maintain about 75 watts output while pedaling. People who train, and bike regularly have been known to do 120 watts. Note, this is sustained for long periods of time, not burst output, which can be 300 or more watts for short periods. This flywheel unit does 500 watts for 4 hours.


  • When I was a kid, my dad was a mainframe operator. They had something similar for power conditioning in a 4 foot high 6x8 foot box with an IBM label on it. I only found out about it because it was the only thing making noise after I hit the EPO switch (I was like 6 years old, and they didn't have a Molly guard on it... Gimme a break.). In retrospect, it was remarkable that he continued to answer my questions at that point. :-)


  • Caterpillar and several other companies make smaller ones (file cabinet sized). Check out Cat here [].

  • idaho. the town full of aryan nutbags.


  • The average home washing machine consumes about 520 watts of power. So in four hours it uses 2.1 kWH of energy. But if a washing machine goes crazy for four hours, I really doubt that it could reduce a building to rubble

    That's the thing about kinetics: a 150# washing machine spinning at 2-5 rps is a whole hell of a lot less dangerous than an 850# disk spinning at 1000+rps.

    Kind of the same way you can stand under a 60 watt lightbulb for 4 hours and not notice, while a 50 watt laser will cut your arm off in 5 minutes.

  • It's not unusual to use AC motor-generator sets with flywheels for power cleanup. Before switching power supplies, IBM and Cray mainframes used to come with such units, converting power to 400Hz to allow smaller transformers.

    I used to work in a mainframe installation that had a M/G set with a small flywheel, just to get rid of power spikes. It was synchronous, 60Hz in and out, vertical shaft, and about half the size of an oil drum. The installation was in an R&D facility for heavy hydraulic equipment (up to locomotive size), so big surges were common. Worked fine. It wasn't intended to maintain power over a power loss, but it completely stopped surges and spikes.

  • I would disagree with this, and claim that the future looks even more divided. The poor will get poorer (and more numerous) while the rich get richer and play with all their new toys. It's been a constant trend over the whole of human history - the greater the number of people, the less fair the division of resources. There are exceptions to this trend, as with all generalisations, but the statistics bear the argument out. And population will increase, despite (almost) all that War, Famine, Pestilence & Stupidity throw in our way.

  • Sadly, the actual power output contributed by a rigged-up exercise bike is pretty minimal - you have to go at a pretty high rate to provide the same output as a normal lightbulb would require, & not many people can keep up a decent speed for very long. The costs of installing such a system would well outweigh the power benefits, although the exercise provided would undeniably be helpful. A small wind turbine or solar panel system on the roof would almost certainly do much better as a power source.

  • Stanby power generators usually have adjustable Jacket Water Heaters and will start and be ready for full load within 10 seconds per the requirments of NFPA. A flywheel solution is the best because if the flywheel is spinning, you know you have power protection. With batteies, one cell can be bad and your entire system could possible not work. Flywheel backup only lasts for a sort period of time, but if your generator won't start within 10 second, it's not going to... so your S.O.L. I quess you should have bought better equipment like Caterpillar and you generator would have started!
  • The specs page for this thing quotes only a two kilowatt-hour capacity, and a one kilowatt maximum output, with a two hour recharge time (the flywheel's still spinning pretty fast when it's "discharged"; the spin-up time from a dead stop is higher than the recharge time).

    High capacity deep-cycle lead acid batteries trample all over those figures. A quality lead acid 12V battery that can deliver 25 amps (300 watts) for more than seven straight hours (more than 175Ah, at that discharge rate) costs maybe $US400, and weighs maybe 60 kilos. That price might be high; I'm not an expert on the pricing of any battery I can't carry up stairs :-).

    Four of those suckers in parallel feeding your inverter and you've got the flywheel system's sustained output, with more than three times the capacity.

    A plain 1.5kW inverter with output at least somewhat like a sine wave is $US350 or so, for a basic model - more, no doubt, for a fancy standby-power-control pure-sine-wave thingummy. But since Beacon Power don't even quote pricing for their buried half-ton humming monster, you can bet that traditional systems are FAR cheaper.

    OK, I suppose you pay for reliability, and if the thing really does last 20 years with zero maintenance then that's something. But properly treated high-grade lead acid batteries have ten year service lives. And the lead's recyclable; dedicated recycling places will pay you by weight for dead wet lead acid batteries.

  • > The problem is that the batteries need maintaining.

    If they're non-sealed super-long-life units, yes. If they're sealed lead acid (SLA) disposables, no. Even cheap and nasty SLAs manage a five year lifespan; ones with ten or better year spans (as long as they don't get more than a few hundred full cycles in that time - many hundreds of partial cycles are fine) are also widely available. Lead acid has unexciting energy density, but it's an evolved technology, folks :-).

    > Also if the idea of the UPS is to supply power whilst a generator is brought on line
    > then being able to run for 7 hours isn't really relevant.

    OK, no problem. Go for little dinky SLAs that any schmuck can hump around in a backpack then, if you only want a one hour run time.

  • This is the best thing since sliced bread! But... if sliced bread had never come around, I have to ask, what would have been the previous best thing?
  • Just so someone knows, this was not a trolling post. I was actually attempting humor and/or satire, probably rather poorly.

    So, in this case, I think it is a fair assessment that nearly all first posts that are not on topic are deemed flamebait, troll, or overrated. Would you not agree? So being first is bad timing... Word to being the sacrificial lamb!

  • Not to mention that the angular momentum probably had some effect in keeping the ship stable :)

    Well, ok, small flywheel vs. big ship, but eh.

  • Actually, the flywheel module would be buried. Try visiting the actual link and you'll see that is what is done. As far as access for inspections, a well-constructed unit shouldn't require it (I don't know what you'd expect to see anyway - you going to rebalance the flywheel by hand or something?). Perhaps ten years after installation you might need to pull it up, but that could easily be done with a backhoe and about 4 hours time.

    Building an entire structure just to house the flywheel is quite rediculous.

  • You'd never build a support structure like this for this type of generator because it would be too expensive. You'd simply use a different type of generator if you had no place to bury a flywheel type like this.

    ...and you're still a dumbass.

  • Two equally massive flywheels spinning in opposite directions but at the same rate would effectively cancel the effect though. (This has been tried with bicycles to prove that balancing a bike is not actually due to gyroscopic effects).

    Counter rotating flywheels do not cancel gyroscopic effects. Having flywheels in a counter rotating configuration doesn't cancel the tendency of their axes to keep pointing in the same direction. It just reduces the "twisting" effects when you try to point their axes somewhere else.

    Also the other way to get more out of the flywheel is to have a relatively small one spin very very fast, using magnetic or some other near frictionless bearings. Strong materials like carbon fibre are commonly used for such flywheels.

    And many chemical cells can explode violently when discharged at rates higher than their spec allows, especially those high energy+power density cells commonly used in modern power hungry mobile devices.


  • So you put two flywheels inside the satellite, each rotating in a different direction. Not much of a problem really.

    Actually, you have to do this for another reason too; it would be pretty hard to change the direction the satellite is pointing at with a flywheel (gyro) spinning inside it. Put two flywheels spinning in the opposite direction of each other, and the effects pretty much cancel each other out.

  • Yeah, Wired covered this whole story about 6 months ago. One solution was to bury the things underground, with just the top access area poking out. That way if they do break, at least nobody gets hit.

  • From their technical specifications page . . .

    Weight--Flywheel Module: 850 lbs
    Weight--Electronics Module: 200 lbs

    That's a total of 1050 pounds! I'll stick with my 5 pound APC UPS for now. Plus, my landlord would not appreciate 1/2 ton of weight in our second floor computer room!

    The specs [] on the flywheel system are pretty interesting, too. It is definitely big and noisy - more so than my 586 full tower web server box.

  • Flywheel brakes transfer energy to a flywheel to stop the vehicle, instead of just creating waste heat through friction. The energy in the spinning flywheel can then be used to accelerate again.

    Scientific American had an issue dedicated to hybrid automobiles a few years back (I'm too lazy to look up the issue, though I did check their on-line archives -- not there) and there was an article about a research team that designed and built a car with a high-tech flywheel.

    It was a really cool car. It actually used a small jet turbine as the primary power source, because it's an extremely energy-efficient type of engine, but the slick part was the flywheel. In order to make sure the flywheel would hold a "charge" for a long time, they tried to make it completely frictionless. The flywheel didn't have any mechanical supports at all; it rested on a magnetic field inside a vacuum-filled spherical enclosure. A magnetized arm that rotated around the enclosure was used to accelerate and slow the flywheel.

    They said when the flywheel was up to full speed, it would take several months to spin down. The main downside of the flywheel was weight, not only of the wheel itself, but also of its enclosure. The wheel was obviously designed to store a lot of kinetic energy, and the designers worried about what would happen if the enclosure were cracked open during an accident, so they designed it to withstand incredible forces.

  • It's about as heavy as my car. I presume under heavy load it would come to a halt about as fast as my car coasting uphill.

    In reality, when I was in the military (DEC PDP11/35 era/pre IBM PC) we ran off a rotary no break. It had a motor, generator, big electric clutch, and diesel engine. It was the least reliable UPS we had. The problem was related to the big fan load on the system. When the flywheel was used to start the generator after an outage of 5-6 AC cycles, the speed became low quickly causing the inertia of the fan load to reverse current the system while starting the engine. After the engine started, the current by the slowed fans combined with the voltage sag (frequency about 50-55 HZ) from the slow generator tended to drop things offline as overcurrent protection operated, which then spiked the system. Most 60 HZ motors tend to draw lots more current at 50 HZ. To make matters worse, sometimes the engine didn't start right away.

    The best system we had was a fulltime UPS (not standby) with about 20 minutes of battery backed by 4 conventional standby generators. The UPS was online all the time, not a standby UPS. This provided excelent spike protection. It was handeled by the battery charger and battery bank. There was no voltage or frequency changes during an outage. It simply worked. It had two banks of batteries so the batteries could be changed without shutting down. I remember the battery room. Rows and rows of 2 volt cells in fiberglass racks connected to produce 300 volts and fused at 900 amps. To check the water, you needed to break up the groups to 25 cell blocks with switches. About once a year a bank of batteries was deep cycled to test for capacity and all terminal connections were cleaned and checked.

  • I'd love to see their entrprise solution. Would it be larger or smaller than the computer room it was designed to power...

    I'd expect though that you could be a happy energy concious 21st century citizen by reading the Mother Earth news [] which would recommend scrapping the computer instead of getting a flywheel to power it.

    I have to say though, It's certainly an interesting concept.


  • by sacremon (244448) on Friday May 25, 2001 @09:10PM (#197462)
    Do folks realize what the UPS's that server farms are like? Try 5000lb. Where I work, we've got ten such UPS's. For media or bandwidth providers, all you really are looking for your UPS's to do is be on line till the diesel generators can in. Our 25 tons of batteries will last us about 15 minutes. That's enough time to get the 4MW of diesel generators going.

    The real attraction to these is that they live for a long time. Even if you have power problems, they won't be stressed very much, and in the long run, you save money by not having to keep on buying new batteries when the old ones inevitably die, regardless of use.

  • ...but nice technology. I worked for three years with a company who had their own home-made version - 15Kw motor, huge (way bigger than 150lb) flywheel, 10Kva alternator providing power to servers and computers. No vacuum or super bearings but it worked like a charm. We switched over from main (275Kva) genset to small (55Kva) at lunchtimes and at the end of the working day. All this in Guyana where the power company simply couldnt deliver enough power. And I have watched "smart" ups boxes smoulder and fry...
  • Wouldn't you therefore want the flywheel to be as massive as possible? This is a fairly common misconception. When it's something like the flywheel on an internal combustion engine where the RPM's are limited by what it is attached to, then more weight may be necessary. But for energy storage, linked electrically, the limit on RPM's is usually just the strength/density ratio of the material.
    e = m * v^2

    So 2x the rotational rate (at a given diameter) gives 4x the energy stored. So what works best is to use a very strong material and spin it as fast as possible without coming apart.
  • It's so big because it's NOT for PC's. It provides 1,000 W for 4 hours, and their suggested market is telecommunications. Typical small UPS's provide 250 to 500 W for about 15 minutes. 99% of power outages are much less than that. If the lights are out in an office for 15 minutes, they'll probably send people home -- but the phone company switches work just fine in the dark, and should stay up through the longest outages. I can also see this unit as a server backup system when you need extremely high availability, except I didn't drill down deep enough to see the output voltages -- I think telecom systems run on 48VDC, so you'd need a different electronics module for computers.

    It probably could be made in smaller size for a PC, but some of the costs don't scale down well, so I'd expect it to be too expensive.
  • Thus you want a wheel rather than a simple disk. With most of the mass on the rim. No. The energy stored is proportional to the moment of inertia times the square of the rotational rate -- so speeding it up pays off much more than increased moment of inertia. But high speed requires great strength so the flywheel doesn't fly apart. High energy flywheels are usually disks of high strength material, and sometimes even thicker in the middle to give it the strength to hold the rim together.
  • Heh, this reminds me of a practical joke Richard Feynman did using flywheels...

    2 large suitcases
    2 large flywheels
    A nice hotel

    Fasten the flywheels inside of the suitcases, one in each. Point them in the direction of the hotel and spin them up, then close them (looks like two innocent suitcases). Take both suitcases and walk in to the hotel (in a straight line). Get a bellhop to take your luggage. Watch as the bellhop rounds a corner and the suitcases jump out of his hands! He'll probably think your suitcases have been posessed by the devil :-)

  • by President of The US (443103) on Friday May 25, 2001 @08:41PM (#197487) Homepage often do I have to change the hamster?

"Someone's been mean to you! Tell me who it is, so I can punch him tastefully." -- Ralph Bakshi's Mighty Mouse