# "Battery-like device", a.k.a. ultracapatitor...plausible? **URL:** \ **Category:** Great Debates\ **Created:** [September 7, 2007, 4:06pm UTC](https://boards.straightdope.com/t/battery-like-device-a-k-a-ultracapatitor-plausible/418376 "2007-09-07T16:06:11Z")\ **Posts on this page:** 19\ **Page:** 3
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [September 9, 2007, 12:00am UTC](https://boards.straightdope.com/t/battery-like-device-a-k-a-ultracapatitor-plausible/418376/41 "2007-09-09T00:00:07Z")
[QUOTE=Q.E.D.] So that if the flywheel asplodes or breaks free, it won’t kill people? [/QUOTE] See my post #25 ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [September 9, 2007, 2:19am UTC](https://boards.straightdope.com/t/battery-like-device-a-k-a-ultracapatitor-plausible/418376/42 "2007-09-09T02:19:44Z")
[QUOTE=beowulff] See my post #25 [/QUOTE] So you claim. But, the folks from Beacon claim they have such a flywheel. Whether they do or not is irrelevant to the point of my post which was that if such a flywheel existed, putting it underground would make sense because there IS a risk of it flying apart or breaking free. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [September 9, 2007, 2:37am UTC](https://boards.straightdope.com/t/battery-like-device-a-k-a-ultracapatitor-plausible/418376/43 "2007-09-09T02:37:45Z")
[QUOTE=Q.E.D.] So you claim. But, the folks from Beacon claim they have such a flywheel. Whether they do or not is irrelevant to the point of my post which was that if such a flywheel existed, putting it underground would make sense because there IS a risk of it flying apart or breaking free. [/QUOTE] Well, duh. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [September 9, 2007, 2:40am UTC](https://boards.straightdope.com/t/battery-like-device-a-k-a-ultracapatitor-plausible/418376/44 "2007-09-09T02:40:11Z")
Then why did you ask? ---
**Author:** ![Enter\_the\_Flagon](https://avatars.discourse-cdn.com/v4/letter/e/b9bd4f/32.png) [@Enter\_the\_Flagon](https://boards.straightdope.com/u/Enter_the_Flagon)\ **Post date:** [September 9, 2007, 4:55am UTC](https://boards.straightdope.com/t/battery-like-device-a-k-a-ultracapatitor-plausible/418376/45 "2007-09-09T04:55:55Z")
These guys are behind the times. The folks at MIT announced the development of a carbon nanotube ultracapacitor over a year ago: > **[Researchers fired up over new battery](https://news.mit.edu/2006/batteries-0208)** "Joel E. Schindall, the Bernard Gordon Professor of Electrical Engineering and Computer Science (EECS) and associate director of the Laboratory for Electromagnetic and Electronic Systems; John G. Kassakian, EECS professor and director of LEES; and Ph.D. candidate Riccardo Signorelli are using nanotube structures to improve on an energy storage device called an ultracapacitor… …This work was presented at the 15th International Seminar on Double Layer Capacitors and Hybrid Energy Storage Devices in Deerfield Beach, Fla., in December 2005." At least the people at MIT have a solid reputation… ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [September 9, 2007, 12:38pm UTC](https://boards.straightdope.com/t/battery-like-device-a-k-a-ultracapatitor-plausible/418376/46 "2007-09-09T12:38:48Z")
[QUOTE=beowulff] Great. Another AstroPower. You want to know how much money I lost on them? Until Beacon’s technology is proven, manufacturable, and cost-competitive, they’re just blowing smoke, as far as I’m concerned. And, I notice these things are buried underground. I wonder why? [/QUOTE] Hey, I’m not promoting the stock or the product. I am not shareholder and for good reason. It _isn’t_ cost competitive with batteries and batteries will only get lighter and cheaper. Their niche is for locations where changing batteries out is extremely difficult or in which conditions are so harsh that batteries do not work well and that is a small niche indeed. But that speaks to the advances in batteries not to the false claim that “Nobody has ever designed a flywheel that can store a reasonable amount of energy, and still not fail catastrophically (and dangerously).” From [Beacon’s website:](http://www.beaconpower.com/products/EnergyStorageSystems/faqs.htm) > [@](#): > > 1. Are flywheels safe? > Based on extensive analysis, careful design and thorough testing, the flywheel energy storage system units have been UL listed for electrical and mechanical safety. More recently, the Smart Energy flywheel system passed with flying colors the Telcordia Level 4 earthquake test - the equivalent of a 7.6-Richter scale disturbance for 40 seconds - without failure. These industry standard ratings are results of the extensive work Beacon Power has invested in verifying safety through real world testing. In addition to several redundant software and hardware systems to prevent over-speeds, Beacon Power has conducted testing to ensure that, in the event of failure, our flywheels shut down benignly. Since flywheels do store a tremendous amount of energy, which should not be released quickly, the composite rim is designed to contain rotor components. The system engineering has proven to release energy slowly, thus preventing any potential risk. > > 2. How are flywheels installed? > It depends on the model. The Smart Power ESU is typically installed above ground on a concrete/steel mounting plate. Smart Energy series ESUs are typically installed underground on a prefabricated concrete pad, and the FEM is installed above ground, generally on an existing or prefabricated pad. Alternative installation plans and configurations are possible, depending on customer requirements. and from a linked page > [@](#): > > Beacon’s flywheels are installed underground to free space and improve site aesthetics. All of which is a hijack from the op and just meant as a simple correction of a mistaken belief. **Enter the Flagon** the issue isn’t if carbon nanotube ultracapacitors are possible or exist. The issue is if EEstor’s performance claims are real or even possible. [MIT’s team](http://www.technologyreview.com/NanoTech/wtr_16326,303,p1.html) claims they > [@](#): > > have found what they believe is a way to improve the endurance of ultracapacitors several-fold – allowing the devices to retain the power and longevity advantages, while storing about as much energy as the batteries used in hybrids. … The main hurdle the new technology is likely to face is not technical but economic. “The nanomaterials are probably a hundred or a thousand times more expensive, today, than the materials that we use,” says Michael Sund, spokesperson at Maxwell Technologies … However, the MIT researchers hope that over time, and with help from economies of scale, nanotube ultracapacitors can be made for the same cost as batteries. (Maxwell, btw, is indeed using ultracaps in the Chinese bus market where their regeneration advantages with braking are a plus.) Meanwhile EEstor’s claims are not a just a several fold increase, they claim a [whole 'nuther thing](http://www.autobloggreen.com/2007/01/31/more-on-eestors-ultracapacitor-can-we-believe-the-hype/) > [@](#): > > EEStor’s EESU, a ceramic ultracapacitor with a barium-titanate dielectric, or insulator, is claimed to break free of the traditional limitations of small energy storage found in other ultracapacitors. Apparently they have achieved an exceptionally high specific energy and permittivity - the ability of an substance to store electrical energy in an electric field. Normally an ultracapacitor has a permittivity rating of 20 to 30, compared to the claimed EESU rating of 18,500 plus. As you can imagine, such claims have raised questions amongst experts who hold concerns that such ceramic materials can survive and function properly in vehicle applications. So the questions are:[ul] [li]Can they make it at all?[/li][li]Can they make it so that it will survive use in a car?[/li][li]Can they make it with the capacity as advertised at a price point that is competitive with Li-ion or Li-polymer batteries?[/li][li]Is their claim of a five minute recharge for 500 miles more than BS or minimally something that is theoretically possible but not ever going to be realistically possible in a home setting and maybe not ever even in a special power charging station setting?[/li][/ul]Making claims is easy. Making an ultracap that does what they say theirs will be able to do, that will be the hard part and they have not shown any evidence of having done so. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [September 10, 2007, 7:59am UTC](https://boards.straightdope.com/t/battery-like-device-a-k-a-ultracapatitor-plausible/418376/47 "2007-09-10T07:59:32Z")
[QUOTE=gazpacho] Don’t they get around gyroscopic effects with counter rotating flywheels? [/QUOTE] I don’t think that will make it anything but worse - counter-rotating wheels would aleviate torsion effects, but not the gyroscopic ones - which are rooted in the law of conservation of momentum - when you try to tilt a gyroscope, you’re essentially trying to divert a fast-moving object onto a different path. ---
**Author:** ![brossa](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/brossa/32/3040_2.png) [@brossa](https://boards.straightdope.com/u/brossa)\ **Post date:** [September 10, 2007, 12:40pm UTC](https://boards.straightdope.com/t/battery-like-device-a-k-a-ultracapatitor-plausible/418376/48 "2007-09-10T12:40:03Z")
[QUOTE=Mangetout] Unless the flywheel was spinning on a vertical axis, but then it would descend hills on its rear wheels only and ascend them on the front pair. [/QUOTE] Sure, it starts out that way, but next thing you know it hops up onto one tire and then throws itself right off the hill. Fucking precession! ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [September 10, 2007, 3:15pm UTC](https://boards.straightdope.com/t/battery-like-device-a-k-a-ultracapatitor-plausible/418376/49 "2007-09-10T15:15:21Z")
Just out of interest, what it the likely effect of mechanical failure cause by damage to a hypothetical supercapacitor such as being discussed here? - let’s say one that it capable of storing enough charge to power a vehicle for 500 miles. I’d have thought it would have to be a pretty big boom - more so than a fuel explosion, surely. ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [September 10, 2007, 6:03pm UTC](https://boards.straightdope.com/t/battery-like-device-a-k-a-ultracapatitor-plausible/418376/50 "2007-09-10T18:03:11Z")
[QUOTE=Mangetout] Just out of interest, what it the likely effect of mechanical failure cause by damage to a hypothetical supercapacitor such as being discussed here? - let’s say one that it capable of storing enough charge to power a vehicle for 500 miles. I’d have thought it would have to be a pretty big boom - more so than a fuel explosion, surely. [/QUOTE] I’d be more worried about arcing in the case of voltage leakage and/or dielectric breakdown. You know the safety warnings about opening up a CRT-based televison or monitor and discharging the capacitors with a plastic handled screwdriver? Imagine a charge several orders of magnitude larger. That’ll straighten your curlies. At any rate, a capacitor is really a poor way of storing and delivering energy for extended periods of time. It’s nothing like a battery or fuel cell, which upon closure of a circuit delivers current along a relatively flat voltage potential. You can get about 70% efficient recovery of energy from NiMH batteries, and \>95% from LiON batteries and fuel cells. A capictor’s energy and discharge rate is related to the potential across it, however, which means that you have to either have a highly variable step-down to your operating voltage and a regulator that opens and closes the circuit to prevent unintented discharge, or a large bank of capacitors and accept a slower discharge rate. Capacitors are great for storing up a bunch of energy when you want a sudden burst of electrical power, as in a particle accelerator or Z-machine, or as an accumulator for charge but no so great at storing energy for long durations. Stranger ---
**Author:** ![David\_Simmons](https://avatars.discourse-cdn.com/v4/letter/d/9de053/32.png) [@David\_Simmons](https://boards.straightdope.com/u/David_Simmons)\ **Post date:** [September 10, 2007, 7:18pm UTC](https://boards.straightdope.com/t/battery-like-device-a-k-a-ultracapatitor-plausible/418376/51 "2007-09-10T19:18:28Z")
[QUOTE=Stranger On A Train] At any rate, a capacitor is really a poor way of storing and delivering energy for extended periods of time. It’s nothing like a battery or fuel cell, which upon closure of a circuit delivers current along a relatively flat voltage potential. You can get about 70% efficient recovery of energy from NiMH batteries, and \>95% from LiON batteries and fuel cells. A capictor’s energy and discharge rate is related to the potential across it, however, which means that you have to either have a highly variable step-down to your operating voltage and a regulator that opens and closes the circuit to prevent unintented discharge, or a large bank of capacitors and accept a slower discharge rate. Capacitors are great for storing up a bunch of energy when you want a sudden burst of electrical power, as in a particle accelerator or Z-machine, or as an accumulator for charge but no so great at storing energy for long durations. Stranger [/QUOTE] Right on. As I wrote in a previous post, with a big enough capacitor and a voltage of 440 V you can store the equivalent of the available energy of a tank of gasoline by charging at 100 A for about an hour. However the energy is proportional the the square of the voltage so when you have half emptied the “tank” the voltage is down to 0.707 of 440 or about 311 V. In addition, the lower the voltage left on the capacitor the more current you must take in order to maintain constant power. A pretty sophisticated motor control circuit is needed to accomodate the large difference in voltage input to the system. I would be interested in seeing how those Japanese trial buses do it. Maybe they charge frequently at the stops in order to keep the “tank” nearly full and the voltage relatively constant. ---
**Author:** ![XT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/xt/32/456_2.png) [@XT](https://boards.straightdope.com/u/XT)\ **Post date:** [September 10, 2007, 7:21pm UTC](https://boards.straightdope.com/t/battery-like-device-a-k-a-ultracapatitor-plausible/418376/52 "2007-09-10T19:21:13Z")
[QUOTE=David Simmons] I would be interested in seeing how those Japanese trial buses do it. Maybe they charge frequently at the stops in order to keep the “tank” nearly full and the voltage relatively constant. [/QUOTE] That’s exactly what they do. IIRC they get partial charges along the route and then fully recharge when they get back to their home base. -XT ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [September 10, 2007, 7:22pm UTC](https://boards.straightdope.com/t/battery-like-device-a-k-a-ultracapatitor-plausible/418376/53 "2007-09-10T19:22:28Z")
Modern switching regulators can maintain \>90% efficiency over a 4:1 input voltage range. I don’t think the discharge curve of a capacitor is a serious impediment. ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [September 10, 2007, 7:27pm UTC](https://boards.straightdope.com/t/battery-like-device-a-k-a-ultracapatitor-plausible/418376/54 "2007-09-10T19:27:36Z")
[QUOTE=beowulff] Modern switching regulators can maintain \>90% efficiency over a 4:1 input voltage range. I don’t think the discharge curve of a capacitor is a serious impediment. [/QUOTE] A 4:1 range is rather limited, particularly if you want a very compact bank of capacitors storing a few hundred kilowatt-hours of energy at a charge. What about 50:1 or 100:1? I’m not seeing the advantage over extant or near-future advances in fuel cells and NiMH batteries, unless these “ultracapacitors” are order of magnitude more efficient than such, and even then there are significant safety and operating issues. Stranger ---
**Author:** ![David\_Simmons](https://avatars.discourse-cdn.com/v4/letter/d/9de053/32.png) [@David\_Simmons](https://boards.straightdope.com/u/David_Simmons)\ **Post date:** [September 10, 2007, 7:48pm UTC](https://boards.straightdope.com/t/battery-like-device-a-k-a-ultracapatitor-plausible/418376/55 "2007-09-10T19:48:20Z")
[QUOTE=beowulff] Modern switching regulators can maintain \>90% efficiency over a 4:1 input voltage range. I don’t think the discharge curve of a capacitor is a serious impediment. [/QUOTE] That means that in my example you could recover 94% of the energy before the regulator gave up. That’s pretty good. Shows what can happen to the state of the art in the 26 years that I’ve been retired. 😉 ---
**Author:** ![gazpacho](https://avatars.discourse-cdn.com/v4/letter/g/6f9a4e/32.png) [@gazpacho](https://boards.straightdope.com/u/gazpacho)\ **Post date:** [September 10, 2007, 11:59pm UTC](https://boards.straightdope.com/t/battery-like-device-a-k-a-ultracapatitor-plausible/418376/56 "2007-09-10T23:59:57Z")
[QUOTE=Stranger On A Train] A 4:1 range is rather limited, particularly if you want a very compact bank of capacitors storing a few hundred kilowatt-hours of energy at a charge. What about 50:1 or 100:1? [/QUOTE] With a 4 to 1 range you can get 75% of the stored charge out of the capacitor and 93% of the energy. Because the energy proportional to the voltage squared. I don’t think there is a lot to be gained by bringing the voltage range for the regulator much passed 4 to 1. ---
**Author:** ![Magiver](https://avatars.discourse-cdn.com/v4/letter/m/4491bb/32.png) [@Magiver](https://boards.straightdope.com/u/Magiver)\ **Post date:** [September 11, 2007, 12:42am UTC](https://boards.straightdope.com/t/battery-like-device-a-k-a-ultracapatitor-plausible/418376/57 "2007-09-11T00:42:26Z")
I can’t vouch for a “super capacitor” battery but I’ve personally witnessed a capacitor battery that was in the exact shape/size as a “D” cell (might have been a “C” cell). What I saw was a demonstration of a cordless drill using these batteries. It took about a minute to recharge in the demonstration. The disadvantage was the amount of time the batteries would run compared to a regular cordless battery (about 1 to 3 ratio). The advantage, which correlates to the article, is the ability to fully recharge in less than five minutes. These batteries would run full strength until exhausted and they were much lighter than conventional batteries or capacitors. Imagine a much lighter power drill that will run hard for an hour and then recharge in a couple of minutes. I’ve been looking for these things for over 3 years and haven’t found them for sale yet but I imagine they are in use today. The potential space available in a car for this technology is substantial. If the engine is replaced by small electric motors at each wheel then there is an engine compartment available along with the gas tank and axles. There is also a lot of space available in fender-wells and bumpers. If you turn the hood, trunk lid and roof into solar cells you have a car that gains better mileage while it sits in the sun. I can’t attest to the cost or the cubic volume required for a 500 mile drive but I can guarantee that capacitor battery technology exists. I’ve been excited by this ever since I saw it demonstrated 3 years ago (NASA exhibit). It really left an impression on me for the very reason we are discussing it. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [September 12, 2007, 4:39am UTC](https://boards.straightdope.com/t/battery-like-device-a-k-a-ultracapatitor-plausible/418376/58 "2007-09-12T04:39:54Z")
[More](http://www.greencarcongress.com/2005/02/ldquoextremerdq.html) on flywheels and ultracapacitors in one proposed vehicle! Who’d have thunk? > [@](#): > > AFS Trinity Power Corporation has unveiled a flywheel-supported hybrid technology that the company anticipates will enable fuel economy in the 200–250 mpg range. … AFS Trinity’s approach is to use a flywheel within a flywheel. Its ARC (Active Rotating Containment) flywheel—for which it received a patent in 2002—uses a slower, heavier rotating outer flywheel to contain a much faster, lighter inner flywheel. > > The result is more power per pound, more efficient energy transfer and a neutral gyroscopic effect which will allow vehicular operation without having to use counter-rotating pairs of separate flywheel systems. > > When the flywheel hybrid vehicle runs on electricity alone it will not rely solely on its batteries; the flywheel and ultracapacitors will do the heavy lifting, providing high power over a short duration for acceleration or for quickly capturing regenerative braking energy. Do I ever expect to see it? No. But still a fun idea! ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [September 12, 2007, 7:12am UTC](https://boards.straightdope.com/t/battery-like-device-a-k-a-ultracapatitor-plausible/418376/59 "2007-09-12T07:12:54Z")
> [@](#): > > …a neutral gyroscopic effect … :dubious: [Previous page](https://boards.straightdope.com/t/battery-like-device-a-k-a-ultracapatitor-plausible/418376.md?page=2)