Talk:Flywheel energy storage

message: I'm not sure how this will fit in yet, but I think I'm going to try to add some more on how superconductors are used for keeping flywheels stable. I think it fits in here better than flywheels because everywhere I've seen it been talked about it has been for electricity storage.  If I do add it here, it will come from a school paper I wrote on the subject.  I'll probably work on it in the talk pages for a few days before adding it to the article itself.Lcolson 03:44, 16 November 2005 (UTC)
replies: text: Finished integration and reorganization.  Moved the completed article. Lcolson 21:20, 19 November 2005 (UTC)

text: I see no mention of flywheel energy storage systems "only stor[ing] power for a short period. . ." in the text you quote, nor can I find any contradiction in these sentences. It says: "they could make the things work better; but even without the better-working-ness, energy can be stored for years." -- KyleP 20:57, 5 April 2007 (UTC)
thread_title:  Superconductors for stability 

message: I was wondering why theres so much about the moment of inertia on this page - Especially why it gives so many random inertial constants. It only makes sense to have the rotor be a solid cylinder, because that should have the greatest strength, and thus greatest possible rotation speeds. Why would you make it, for example, a hollow sphere?? Fresheneesz 21:12, 21 July 2006 (UTC)
thread_title:  interial constants 

message: This page needs some math to predict the stresses on a spinning cylinder. I found one equation, but I don't think its correct for this application at least. Fresheneesz 23:22, 30 July 2006 (UTC)
thread_title:  Stress 

message: I got to the "flywheel energy storage" page from the "zero-emission vehicles" page, so I rather hoped there'd be something on the page about their potential for use in cars.  A few years ago--I think it was 1997--I remember seeing a presentation by Ben Rosen and his brother, who had developed a hybrid-electric car powertrain using a high-speed flywheel for energy storage.  Basically, it was a gas turbine generator, a flywheel for energy storage, and a drive-by-wire electric system with a motor on each wheel, which could reverse for regenerative braking.  The flywheel was definitely the gem of the system, though, and used most of the high-tech design elements described in this article--carbon fiber reinforcement, magnetic bearings, magnetic energy transfer, and so on.  (A hollow cylinder, if I recall correctly.)  I think it represented more or less the state of the art, and they did in fact make a working powertrain out of it.  Might make for an interesting addition to the article, anyway, particularly if it's going to be linked from the ZEV page.  I'm not sure if it's too specifically commercial, though.  I'm new on Wikipedia, so I'm not really comfortable editing articles yet.
Emertonom 18:30, 21 August 2006 (UTC)
replies: text: Take a look at Gyrobus MGTom 23:21, 27 September 2006 (UTC)
thread_title:  Application: electric cars? 

message: There's a "factual inaccuracy" label on one of the sections of this article, but no discussion here on the talk page about why.  I'm going to yank it, and hopefully if there really is something wrong with the article the original accuracy questioner will come back and put a note here for us.
Joachim Heck 14:33, 30 October 2006 (UTC)
thread_title:  Inaccuracy label but no discussion! 

message: :"Quick charging is done in less than 15 minutes."
This makes no sense in the context of the article. What is quick charging? Charging of what, the flywheel's momentum, or of a battery, or of the generator? A battery within the system, or any external battery? 15 minutes has no relevance if it is not related to another quantity. Is this "charge" always a certain amount of Joules, Coulombs, Volts, etc.? -- KyleP 20:37, 5 April 2007 (UTC)
replies: text: I replaced the sentence with a quote from ScienceNews; I hope this helps. — Sebastian 16:27, 31 May 2007 (UTC)
thread_title:  Quick Charging? 

message: The reference for the line "flywheels were used in buses..." says nothing about such a project!  —Preceding unsigned comment added by 74.67.57.245 (talk) 18:34, 21 December 2007 (UTC)
thread_title:  Vancouver bus flywheel demonstration? 

message: I removed the following paragraph from the "Applications" section, since it doesn't even mention applications. This might make sense in a history section, but I'm not sure how big that would get if we dedicated a paragraph to every researcher of the last 30 years. It may make more sense to create an article for the redlink. — Sebastian 16:22, 31 May 2007 (UTC)
thread_title:  Nourbey Gulia 

message: Flywheel Energy Storage (FES) works by accelerating a rotor (flywheel) to a very high speed and maintaining the energy in the system as rotational energy. -- Good!
The energy is converted back to electricity by slowing down the flywheel. -- Eh??
Where does this "electricity" assumption come from? You can store energy in a flywheel without ever having any electricity anywhere! This is maybe a bad example, but just to illustrate the point 
http://www.xtrac.com/pdfs/Torotrak_Xtrac_CVT.pdf
describes a formula one race car flywheel energy storage. "The energy is converted back to electricity by slowing down the flywheel" is complete rubbish. Kinetic energy was put into the flywheel during braking and the flywheel puts kinetic enery back into the car on acceleration.
Is this an article on Flywheel energy storage, or about somebody's particular product with a specific application?
Crysta1c1ear 15:59, 7 June 2007 (UTC)
replies: text: I changed the headline to clarify the good point you are making. I will also change the article to include this technology. — Sebastian 19:35, 7 June 2007 (UTC)
thread_title:  Electricity is not needed 

message: "Strictly speaking, they would exert a huge torqueing moment around the central point, trying to bend the axle. However, if the axle were sufficiently strong, no gyroscopic forces would have a net effect on the sealed container, so no torque would be measured externally."
Can anyone explain how this is true?
If there's a torque on the axle, how does one isolate that from the outside world?  The axle has to be connected to the car in some way, so would there not be a torque on the car, too?  —Preceding unsigned comment added by Pediddle (talk • contribs) 17:00, 16 September 2007 (UTC)
thread_title:  Gyroscopes in opposite directions? 

message: The UPS section needs a dose of honesty, in conjunction with the disadvantages section.  What sizes of UPS storage systems are practical for flywheels?  And for such systems, if they sit around day after day fully charged, but never utilized, how much energy do they consume total, just to stay charged and operational?  It looks like they are much worse than batteries on this important parameter, quite important in such applications -- let's have some facts! -69.87.203.168 (talk) 02:46, 24 November 2007 (UTC)
thread_title:  UPS steady-state losses 

message: It would be nice to have some discussion about the lifetime of the energy storage: I'd imagine that due to friction etc. storage efficiency would degrade over time. it would be good to know the longest timespan storage that flywheels currently operate at: days weeks? hours? --naught101 (talk) 00:33, 21 February 2008 (UTC)
replies: text: If the flywheel is magnetically beared and kept in vacuum, there's only very little friction during storage, mostly caused by Eddy_current. I'd think most degeneration of material is caused when energy is added (wheel is accelerated) or drawn. Then you get massive distortions throughout the material which probably cause microfractions over time. Thus I would assume that the lifetime of a flywheel mostly is dependant on how often it gets accelerated and deccelerated and not so much on how long the energy is stored in particular. For the latter I'd say a superconducting magnetic bearing could hold a flywheel for years without much energy loss for the upkeep cost for the superconductivity of course :) --84.56.197.45 (talk) 16:09, 3 March 2008 (UTC)
thread_title:  Physical characteristics 

message: There is an article in Popular Mechanics about replacing the steam launcher on aircraft carriers with electric-flywheel technology. This can handle much larger loads and recharge much faster and requires a huge amount of less maintenance.  —Preceding unsigned comment added by 41.112.146.254 (talk) 10:42, 20 May 2010 (UTC)
thread_title:  Use in Aircraft Carriers 

message: As per http://www.wired.com/autopia/2010/02/porsche-builds-a-competition-caliber-hybrid/. Should probably be added to motorsports section with citation.  — Preceding unsigned comment added by 98.149.135.239 (talk) 03:06, 2 June 2011 (UTC)
replies: text: I believe Williams have been developing their own flywheel-based KERS system; however AFAIK all current KERS systems use electrical storage. Mr Larrington (talk) 14:59, 15 August 2011 (UTC)
thread_title:  New non-KERS application of flywheel energy storage for racing 

message: I added this:
Flywheels have also been proposed for use in continuously variable transmissions. Punch Powertrain is currently working on such a device.Punch Powertrain working on flywheel-equipped CVT
If it isn't upto standard, improve the information.  — Preceding unsigned comment added by 91.182.91.212 (talk) 11:25, 13 September 2012 (UTC)
thread_title: Added this

message: I'm not seeing very many web references to concrete flywheels. Are they used? Apparently it should be possible to construct them inexpensively, using an outer high-tensile cover for compression against fracture. 
It's unclear what the failure mode would be of a concrete flywheel. If the release energy is high enough, it may fracture all the concrete from the sand, resulting in a powdered cloud of debris that may contain the failure kinetic energy about as well as an all-composite filament wheel.
--DMahalko (talk) 06:53, 19 December 2012 (UTC)
replies: text: Using Concrete for flywheels wouldn't make a lot of sense. Concrete is strong in compression but weak in tension, hence its use in building columns, with steel reinforcing handling the tension.  The stresses in a flywheel are all tensile.--Graham Proud (talk) 10:38, 18 January 2014 (UTC)
thread_title:  Concrete flywheels, failure modes? 

message: Hi, I was thinking this page need a discussion of the vacuum pump requirement for the vacuum systems.
My experience with vacuum comes from UHV systems, where the pressure will rise considerably if there is no active pumping of the system for prolonged time, even with all the specially-designed fittings.
But for the purely mechanical properties of vacuum, there are much less strict requirements than UHV.
Does anyone know whether it is feasible for a flywheel system to simply pump down the pressure and disconnect the pump? Would such a system keep vacuum for years on end?
If not, the pump system should be seen as an integral part of the flywheel. Therefore the power consumed by the pump and its maintenance  requirement should be brought in for a fair comparison with batteries and other power storage devices.  MigB (talk) 11:14, 22 March 2014 (UTC)
replies: text: Looking at the Beacon Power product, they are vacuum sealed.  Certainly vacuum equipment would be required in the factory but not within the device.--Graham Proud (talk) 15:06, 22 March 2014 (UTC)
thread_title:  Vacuum pump needs 

message: Some of these systems - eg for physics labs - generate DC, others might generate AC. Some have separate motors and generators. It would be great to have more detail on this. Duration of input/output and typical storage times might be interesting ? Some are optimised for peak power output (charging at lower power). - Rod57 (talk) 14:16, 7 December 2015 (UTC)
thread_title:  AC or DC 

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thread_title:  External links modified 

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thread_title:  External links modified 

message: Are there any concepts externally mechanically supported? Like launch loop or "maglev trains" going in circles. F = m⋅a = m⋅v^2 /r = 2K/r so K=F⋅r/2 is about the energy stored.(F the force the system can carry) If the strength of the disc is also still used can roughly add that. Or just not hearing about that because negatives not reported?(indeed, afaics, none seem to be sufficient, launch loop is fast enough, but requires that large radius)2001:984:6FB5:1:8A4B:AF78:1B75:1ECD (talk) 00:09, 24 March 2016 (UTC)
thread_title:  Externally mechanically supported kinetic energy storage? 

message: This article could talk about the technical and economic viability of flywheels for grid connected electricity generators, particularly intermittent renewable sources such as solar and wind.  — Preceding unsigned comment added by Jray310 (talk • contribs) 08:10, 22 October 2016 (UTC)
thread_title:  Storage for grid connected electricity generators 

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thread_title:  External links modified 

message: The comparison to electric batteries section suggests only one way in which flywheels are not superior to electric batteries is limited flexibility in terms of shape. However, the use of batteries seems far more prevalent than flywheels, would suggest there must be some other advantages to battery storage. Is this section really capturing the whole picture, or is it overly biased in the direction of flywheels? —Salton Finneger (talk) 18:07, 28 February 2017 (UTC)
replies: text: The application makes a world of difference, for small or portable, or flat as in a EV, batteries have no competition from flywheels, as the size of the battery industry proves. For the much rarer stationary applications it's all about cost, when a UPS is small, it will use a battery, when the storage gets to hundreds of kW, a kWh of spinning steel is cheaper than a kWh of chemical battery, when storage becomes even larger, a kW of falling water is cheaper than a kW of spinning steel. The "Comparison_to_electric_batteries" leaves out the little detail that there aren't small flywheels for storage. Dougmcdonell (talk) 21:02, 1 March 2017 (UTC)
thread_title:  Comparison to electric batteries 

message: I was taking a look at the specific energy equation found in this article and, as far as I can tell, this equation is not dimensionally consistent. For it to be dimensionally consistent K should have dimensions corresponding to (L)^-2. I'm sorry if this is not the correct format to submit my doubt.
213.99.46.50 (talk) 14:46, 3 May 2017 (UTC)
thread_title:  Possible error in specific energy equation? 

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thread_title:  External links modified 

message: was a result of an x-time repeated experiment to use the residual enegy of the heavy turbine rotors as flywheel uninterruptible power supplies. To spare the huge, expensive and leaking accumulators. And they have been very close to solve the generator exciter regulation problem, unfortunately the necessary integrated circuits have been under US technological embargo at this time :(
85.216.197.77 (talk) 19:57, 18 July 2021 (UTC)
thread_title:  Chernobyl Disaster 

message: I'm not sure how to use references, but I was curious about:
The Helically Symmetric Experiment at the University of Wisconsin-Madison has 18 one-ton flywheels, which are spun to 10,000 rpm using repurposed electric train motors.
https://news.wisc.edu/one-of-a-kind-fusion-experiment-comes-online/
Does anyone have more information about this hardware?
50.5.47.22 (talk) 03:22, 28 November 2021 (UTC)
thread_title:  Helically Symmetric Experiment flywheels 

message: Per a 2018 Planet Money (NPR) episode, PG&E's 2016 agreement with a California company to construct a flywheel energy storage system in Fresno did not yield usable results. Nieuwe Nederlander (talk) 00:55, 23 February 2022 (UTC)
thread_title:  PG&E grid storage update