Flywheel energy storage

yifu

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Mechanical energy storage is capable of greater capacity, reliability and more cost efficient energy storage than traditional battery system. Hydrodynamic, air pressure reservoirs and flywheels have been around for sometime but are out of reach of the public, and most larger scale flywheels are used in physics labs only.

So, i've been on kickstarter, which is home to many amazing open source projects and i saw this
http://www.kickstarter.com/projects/1340066560/velkess-energy-storage
The velkess flywheel! Weighting just under 750lb it stores 15kWh of electricity, which is amazing! What's more is that with the magnetic bearings it looks to be a low upkeep system that should remain functional much longer than batteries and much cheaper as well. With the development of higher efficiency solar panels and other cheap alternative sources of energy (my solar panels were around 2000 with the government rebate) this could be the future of our energy grid. I've already put in money into the project and will be looking foward to its development. Any thoughts?
 

AnAppleSnail

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Neat. I do like mechanical energy storage for simplicity. Large elevated water bodies are neat when you have that terrain. Some MIT-types are considering large concrete pressure vessels for energy storage as well.

I do NOT like when energy storage companies talk about 'producing' 2kW of power from a storage (And at 0.5 kW that's for 15 minutes). The real term should be release, but that's a language quibble. Distributed power storage is (As they say) a REAL need for distributed grids. Of course, any install that stores 750 kWh should have a pro-install-quality automatic disconnect switch so you don't electrocute linemen in power outages.

Audi did some impressive power storage in their LeMans vehicle. I believe it was similar technology (Store braking energy going into a turn, release in a burst of acceleration out of the turn), although their flywheel may have been rigidly mounted for race performance.
 

badtziscool

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I'm not sure what's so special about a velkess flywheel. It just looks like a non-rigid flywheel that's afixed a certain way that allows it to wobble around without affecting the mounting point. I'd be concerned with "internal losses" with a system like this. If the flywheel is made of a non-rigid material, every time the flywheel flexes or contorts to "self balance" itself, it's using up energy. With that, you have to ask how long can the flywheel hold the energy before it becomes unusable. Also, for 750lb to store 15kWh of energy, how fast does it need to spin? I'm guessing pretty fast. And if it needs to spin that fast and if it's not aerodynamic, it's going to lose a lot of energy from the turbulence created. I supposed you could put the whole assembly in a vacuum, but a structure this large under a vacuum needs to have a substantial container, and that might make something like this not cost effective.
 

Steve K

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Mechanical energy storage is capable of greater capacity, reliability and more cost efficient energy storage than traditional battery system. Hydrodynamic, air pressure reservoirs and flywheels have been around for sometime but are out of reach of the public, and most larger scale flywheels are used in physics labs only. <snip>
.... Any thoughts?

Flywheels are clearly better, which is why you see them used in cars instead of lead acid batteries, or in the Tesla roadster instead of nimh, or in diesel-flywheel submarines instead of them being diesel-electric submarines. Yes... no question that flywheels have batteries beat in all regards!

or... if you've been exposed to some general science publications for at least 20 or 30 years, you'd recall hearing stories on a regular basis about how the latest flywheel technology was about to be used for energy storage in buses or powerplants, etc. People have been spending money on ways to improve flywheels ever since they were invented, and you can see how widely they are used. Flywheels with magnetic bearings and housed in a vacuum for efficiency are nothing new. Why would this kickstarter program be considered a real contender? Especially when the flywheel looks like a bunch of kevlar cords tied up in a bunch?

If these guys were demonstrating specific achievements in terms of energy density, operating cost, material cost, etc., then I might stop to consider their prospects for success, but demonstrating that they can spin a loop of rope in a can is not sufficient to get me to fund them.
 

yifu

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Sure, the energy itself is not new but what is new is that this seems to be a concerted effort to bring it to the public or at least a pilot into the process of making it available for an acceptable cost. Many other forms of off-the-grid energy storage are available such as battery banks or generators and many households already have access to those so there is a market for it.

In many parts of Australia, solar panels are a common sight and most were installed at a subsidized rate. Currently, the grid has a buy back policy in which it pays for the electricity generated by such panels and takes it off the bill but this really messes up with the electric grid since it only operates during daylight, complicating things like load balancing and baseline loads for the gas generators. Wouldn't it better to have a more localised storage system? A reasonable 6 panel 3kW panel connected to a flywheel would be able to power a house for the day. This would be feasible for most sunny countries and other alternative energy sources might arise in future and they can be connected to such a system as well.
 

Steve K

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Clearly flywheels have attractive characteristics. The ability to move energy into and out of them quickly is something that batteries have a hard time matching. The conceptual simplicity is attractive too... no need to worry about chemicals or issues with charging and discharging carefully.

My issue is more along the lines of putting some numbers on the claims of Velkess. Show me how their flywheel system compares to other technologies or other flywheel manufacturers. Show me how other flywheel designs failed, and how theirs fixes the problem. As far as I can tell, they're just saying that they are doing something different without saying why or how the other designs are deficient.

A very brief web search brings up a company that was using flywheels for storing excess grid energy and then releasing it when needed. The company is Beacon Power...
http://en.wikipedia.org/wiki/Beacon_Power
well.. maybe I should say "was". The wiki page says they had financial problems and have been bought by a private equity company. To quote: "Rockland Capital intends to rehire most of staff and to provide the capital to build a second 20MW plant in Pennsylvania."
At least in this case, a company has tried to produce a large scale flywheel energy storage system, had significant problems of an unknown sort, and now a private equity company appears to be taking another shot at it. In that regard, I don't think Velkess is breaking any new ground.
 

yifu

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Well you certainly cannot fit a 20MW system in your backyard whereas you can with a smaller flywheel which has not previously been available to the public with modest finance. The attractiveness here also involves the concept of living off the grid with a self contained system for people who want to, which is very difficult with current battery technologies.
 

Steve K

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okay.. for a 20MW system, what are the specifics of a flywheel system vs a conventional system, which I assume is a bank of lead-acid batteries. Energy capacity? Cost? Size? Lifetime?


update: a quick search found this flywheel system by the former Beacon Power:
Beacon Power will design, build, and operate a flywheel energy storage frequency regulation plant at the Humboldt Industrial Park in Hazle Township, Pennsylvania. The plant will provide frequency regulation services to grid operator PJM Interconnection. Beacon's technology uses flywheels to recycle energy from the grid in response to changes in demand and grid frequency. When generated power exceeds load, the flywheels store the excess energy. When load increases, the fly- wheels return the energy to the grid. The flywheel system can respond nearly instan- taneously to an independent system operator's control signal at a rate 100 times faster than traditional generation resources. The system does not burn fuel and has zero emissions. The Beacon Gen4 flywheel is designed with 100 kW of output and 25 kWh of energy. Two hundred flywheels will be connected in parallel to provide 20 MW in capacity and can fully respond in less than 4 seconds. The plant can operate at 100% Depth of Discharge with no energy degradation over time and can do so for over 150,000 full charge/discharge cycles. The flywheels are built to last 20 years or more. Virtually no maintenance is required in the mechanical portion of the flywheel system. Flywheel technology has been successfully tested on live grids at scale power in New York and California. The technology achieved system availability of over 97 percent, higher than the average for conventional generators performing frequency regulation. It has been deployed at multi-megawatt scale under New England's Alterative Technologies pilot program. The site has the potential to support the distribution system that connects a nearby solar project to the grid.


another update: also from SmartGridNews, this blurb about a 20MW storage system from A123:
A123 Systems a developer and manufacturer of advanced Nanophosphate lithium ion batteries has announced that AES Gener will order 20MW of A123′s advanced energy storage solutions for a spinning reserve project in Northern Chile.

A commercial 12MW spinning reserve facility is operational in AES Gener's Los Andes substation which is in Chile‘s Atacama Desert, it was AES first implementation of A123 energy storage technology.

Chris Shelton, president of AES Energy Storage said, "The project will utilize A123 lithium-ion batteries to supply a flexible and scalable emissions-free reserve capacity installation for AES Gener. We are excited to work with A123 to improve the performance and reliability of the Chilean power grid".

The A123′s lithium-ion energy storage systems are highly scalable design which consists of modular energy storage racks, power electronics, communications and controls software. The storage systems design and technology enables grid operator’s better control for frequency regulation, spinning reserve and other ancillary services.

Robert Johnson, vice president of the Energy Solutions Group at A123, said "Projects like this and others we are working on demonstrate the commercial viability of our advanced energy storage capabilities, and we expect the technology to play an integral role in increasing the efficiency of ancillary services and enabling the wide-spread integration of renewable energy".

A123 with AES Energy Storage is also expected to complete an energy storage facility in Johnson City, NY sometime in 2011. The new system will supply 20MW of emissions-free reserved capacity to the power market operated by the New York Independent System Operator.

A123 is the largest producer of lithium ion batteries for ancillary services for the power grid and its lithium-ion energy storage systems facilitate the integration of renewable energy sources which offers a cost-effectively hybridize power plants to improve grid stability.


That's a lot of text.. sorry. It does sound like both systems are scaled for utilities, and not for home power. Both articles are a couple of years old, and both companies are now out of business or sold off to private equity companies (is that right?). Neither seems to be economically viable at this point, based on the evidence. Unfortunately, neither blurb provides the basic metrics that would allow you to compare the relative performances of the two technologies.
 
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Chicago X

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Flywheels are clearly better, which is why you see them used in cars instead of lead acid batteries, or in the Tesla roadster instead of nimh, or in diesel-flywheel submarines instead of them being diesel-electric submarines. Yes... no question that flywheels have batteries beat in all regards!

Your sarcasm aside, there is a use for flywheels in automotive applications. You may have heard of a small racing league called Formula 1, or manufacturer Porsche.

http://www.formula1.com/inside_f1/understanding_the_sport/8763.html

http://en.wikipedia.org/wiki/Kinetic_energy_recovery_system

http://www.popularmechanics.com/cars/alternative-fuel/hybrids/porsche-911-gt3r-hybrid-flywheel

http://www.roadandtrack.com/car-reviews/first-drives/2011-porsche-911-gt3-r-hybrid-20
 

orbital

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>>>>> The amount of energy that could be harvested from freight train braking systems using flywheels could be huge,,,
someone should put their thinking cap on for that <<<<<



^^
 

Steve K

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yep, very much aware of that. It does take advantage of the flywheel's ability to quickly store and deliver energy, in addition to not needing to store the energy very long. Batteries are not well suited for this task, but I do wonder about supercaps. I'm fairly confident that Porsche's engineers did an analysis of the various methods of storing energy and selected the freewheel based on its merits. I was just trying to make the point that statements such as yifu's opening sentence are completely without merit.
 

jtr1962

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>>>>> The amount of energy that could be harvested from freight train braking systems using flywheels could be huge,,,
someone should put their thinking cap on for that <<<<<
That problem is easily solved by just electrifying freight lines as is done in most of the rest of the world. The railroad benefits from the lower operating costs/greater line capacity of electric traction. Most of today's electric locomotives feed energy back into the catenary when in dynamic braking mode (i.e. using the motors as generators to slow the train). The power obtained by regenerative braking is utilized by other trains. Diesel locomotives burn up the energy from dynamic braking in resistor grids. Remember the amount of kinetic energy in a freight train is HUGE ( 10,000 tons @ 70 mph = 4.45 GJ = 1236 kW-hr ). There's really no means to store it in something which would comfortably fit on a locomotive. You would probably need 100 tons of lead-acid batteries. There's no way you're having a flywheel which could store that much energy on a train. The gyroscopic forces would likely derail the train on curves. And in the event of catastrophic failure, the explosion would be equivalent to about a ton of TNT.

The problem actually gets worse when you consider that freight trains dynamic brake on downgrades to keep their speed in check. Now you might be talking about a need to store an order of magnitude more energy than the kinetic energy. Like I said, electrification and regen braking are the obvious solutions here.
 

gadget_lover

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Hmmm. It seems that none of the Formula 1 teams opted for the flywheel. Then it was not used at all for a season (or was it two?).

A flywheel that stores a large amount of energy has to be massive or it has to spin very fast. The latter style needs some sort of transmission device to drop the RPMS to a usable range if it is direct drive. That involves losses. If the flywheel is coupled magnetically and spun up using an electric motor, then there are even more losses, similar to used in charging a battery. Inertia limits how fast you can spin up a flywheel. It's not instantaneous.

The Porche uses electric generators as brakes so that it can spin up the flywheels, so it has the associated losses as power is transformed from mechanical to electric to mechanical to electric to mechanical again. . It's not in production, just in test vehicles.

I agree with others... Flywheels may have value in fixed plants for smoothing power supply, but putting a 750 pound device (plus necessary support equipment) in a car is not something that is done lightly. The flywheel effect will impact handling, ride or both. The efficiency is not necessarily better than batteries. The danger in case of failure is not trivial.

Daniel
 

Julian Holtz

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The idea is not bad at all.

The ISS uses Flywheels, which conevniently can also be used to stabilize it utilizing gyroscopic effects:

http://www.grc.nasa.gov/WWW/RT/RT2001/6000/6910tyburski.html

Also:

http://en.wikipedia.org/wiki/Flywheel_energy_storage#Road

I have already heard about the flywheel-powered buses elsewhere. At every bus stop, there where large electric contacts, which were automatically connected to the bus when it stopped under them. A large motor would bring the flywheel to speed during the stop, and act as a generator for the electric motor while driving.

Oh, I see, there is a separate article:

http://en.wikipedia.org/wiki/Gyrobus
 

mattheww50

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Actually just about all large space craft in long term orbit use reaction control wheels to maintain/adjust attitude and provide stability. The wheels are electrically powered, which means they can be 'fueled' from the solar panels, as opposed to consuming fuel that must be carried into orbit at enormous cost, and much would be consumed if reaction control wheels were not utilized.
 

Chicago X

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I agree with others... Flywheels may have value in fixed plants for smoothing power supply, but putting a 750 pound device (plus necessary support equipment) in a car is not something that is done lightly. The flywheel effect will impact handling, ride or both. The efficiency is not necessarily better than batteries. The danger in case of failure is not trivial.

Daniel

In the case of the Porsche system, it weighs in at less than 50 kilos.

Capacity is far less than a typical battery-based system, but it it much better suited to the energy storage and release needs of racing. Very large amounts of energy are released in a short period of time, then recaptured under braking, repeating hundreds of times during a typical race period.

This is much different than the typical energy demands of a family car, but may be suitable for use in some cases. Mail delivery, or other urban delivery vehicles might benefit from the repeated braking cycles more suited for flywheel charging.

Failure issues were heavily studied in the case of F1 usage. A 'frangible' flywheel was developed to help mitigate driver risk in case of a crash. This is not a trivial concern, as evidenced by the requirement of scatter shields in drag racing.
 

gadget_lover

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In the case of the Porsche system, it weighs in at less than 50 kilos.

Capacity is far less than a typical battery-based system, but it it much better suited to the energy storage and release needs of racing. Very large amounts of energy are released in a short period of time, then recaptured under braking, repeating hundreds of times during a typical race period.

The original post was about a 750 lb system, so that's why I mentioned it. The 125 pound unit in the Porche system does not serve the same purpose. One is a prime energy storage, the other is for providing short bursts of power.

I've used a car with regenerative braking for 11 years and it is, in general, a good thing. BUT...

The regen braking has to be perfectly integrated into the system. One of the simple problems is that batteries and flywheels will only store a finite amount of energy. If you max out that storage while hard braking, then you have to seamlessly engage friction based brakes at the exact same rate of deceleration. A sudden change can lead to losing control in the turns.

I LIKE hybrids, but I see the multiple energy transforms in the flywheel system as being less effective than the battery based systems.

Daniel
 

Sub_Umbra

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To propel a vehicle requires a huge amount of exergy. It matters little whether the exergy comes from gasoline or steam or a flywheel spinning at high rpms. The one thing that all systems have in common is that when there is an accident often relatively large amounts of energy are released suddenly with often unpredictable results. When a gas powered car crashes there is often a fire and sometimes an explosion.

When a car driven by a high speed flywheel crashes where will the exergy from the flywheel go? Once the flywheel escapes its housing how many houses may it tear through before it stops spinning????
 
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gadget_lover

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To propel a vehicle requires a huge amount of exergy. It matters little whether the exergy comes from gasoline or steam or a flywheel spinning at high rpms.
....Edited to use the term that was originally in the post.

It does sort of matter. :) Some energy sources are easier to use efficiently. Adding a simple gear to change the speed of a spinning shaft creates a significant loss of power. I seem to recall it was like 3%. Transforming movement to electricity loses some energy as heat. So does charging a battery. Each method of storing energy has it's own drawbacks.

When a car driven by a high speed flywheel crashes where will the exergy from the flywheel go? Once the flywheel escapes its housing how many houses may it tear through before it stops spinning????

They have tried to address that with a flywheel made of fibers that self destructs into a tangled mess when it breaks. I'm not sure what happens to all the energy that it has stored when that happens. Heat? I don't recall the article saying.

Daniel
 
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Sub_Umbra

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It would appear you have purposefully misquoted me. What I actually wrote is still there for anyone to read. I wrote exergy not energy. They are two completely different things. Please correct your misquotes of my post or take them down.

As far as self destructing flywheels go, physics dictates that the lighter it is the faster it must spin to store the same amount of energy. You would appear to be talking about smaller shrapnel at higher velocities. The total energies involved must remain the same, however.
 
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