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Batteries To Store Wind Energy

Soulskill posted more than 5 years ago | from the charging-at-wind-mills dept.

Power 275

Roland Piquepaille writes "Scientific American reports that Xcel Energy, a Minneapolis-based utility company, has started to test a new technology to store wind energy in batteries. The company is currently trying it in a 1,100 megawatt facility of wind turbines in Southern Minnesota. The company started this effort because 'the wind doesn't always blow and, even worse, it often blows strongest when people aren't using much electricity, like late at night.' It has received a $1 million grant from Minnesota's Renewable Development Fund and the energy plant should be operational (PDF) in the first quarter of 2009. If this project is successful, the utility expects to deploy many more energy plants before 2020 to avoid more polluting energy sources."

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Wow! (0, Insightful)

Anonymous Coward | more than 5 years ago | (#26250965)

Look out Xcel Energy, the committee to award the Noble Prize in Obviousness is looking your way.

why was this title red? (-1, Offtopic)

Anonymous Coward | more than 5 years ago | (#26250985)

I saw it red.

Re:why was this title red? (0)

Anonymous Coward | more than 5 years ago | (#26251645)

Don't worry about it, that's just a side effect of the recent communist invasion of Slashdot. So, you know, no more Russian reversals.

What sort of Batteries? (3, Funny)

Anonymous Coward | more than 5 years ago | (#26251001)

I hope it's not 9 volt. Those are hard to find.

Seems silly to use this. (3, Insightful)

Anonymous Coward | more than 5 years ago | (#26251013)

Why are more utilitys not using something like what beacon power is doing.

Storing energy in flywheels. Spin it up when the wind blows. Draw it off when you need it. They last for a very long time when compared to batterys.

Batterys are kind of high priced for a low lifetime. Require all kinds of nasty chemicals to make and need to be disposed of someday. And take HUGE banks to store what a large flywheel would store.

Seems silly...

Re:Seems silly to use this. (2, Informative)

Anonymous Coward | more than 5 years ago | (#26251145)

I believe that more isn't being done with flywheels because storing energy in flywheels costs much more than the NaS batteries.

Re:Seems silly to use this. (4, Interesting)

AndGodSed (968378) | more than 5 years ago | (#26251461)

I remember that flywheels were considered for electric cars as well.

Some of the issues I remember off hand were:

1. Specialized materials needed to build flywheels that are small, yet heavy enough to keep spinning for a long enough time after being "charged"

2. Getting the energy IN the flywheels in the first place - it takes more energy to get them spinning than what you draw from them.

3. Given the high velocities - what will happen when they fly apart? Also, the gyroscopic effects they generate while spinning.

4. The heavy mounts needed to safely position them negated any advantages through increased weight.

I don't know if any of these apply to stationary flywheels built into power plants though...

Re:Seems silly to use this. (4, Insightful)

Meumeu (848638) | more than 5 years ago | (#26251747)

I remember that flywheels were considered for electric cars as well.

Some of the issues I remember off hand were:

1. Specialized materials needed to build flywheels that are small, yet heavy enough to keep spinning for a long enough time after being "charged"

2. Getting the energy IN the flywheels in the first place - it takes more energy to get them spinning than what you draw from them.

3. Given the high velocities - what will happen when they fly apart? Also, the gyroscopic effects they generate while spinning.

4. The heavy mounts needed to safely position them negated any advantages through increased weight.

I don't know if any of these apply to stationary flywheels built into power plants though...

They don't apply for a power plant:

  1. you don't care about the size and you don't need to keep it charged for weeks
  2. you will have it with every design you can come up with, the question is how much do you lose?
  3. put a big container that can contain it if it flies apart, you don't care about gyroscopic effects
  4. not applicable to a stationary plant

Re:Seems silly to use this. (2, Informative)

icegreentea (974342) | more than 5 years ago | (#26251755)

Well, point number 2 is true of any storage solution. From what I remember, very large flywheels rank fairly high in terms of efficiency, especially compared to battery solutions. In a stationary mount, you don't have to worry about gyroscopic affects, and presumably you could build them within enclosures strong enough to contain explosions. Also, apparently the new composites being used upon 'exploding' completely disintegrate, so instead of a supersonic steel shrapnel, you get a crap load of superhot sand. Much easier to contain.

Re:Seems silly to use this. (3, Informative)

kent_eh (543303) | more than 5 years ago | (#26251915)

3. Given the high velocities - what will happen when they fly apart? Also, the gyroscopic effects they generate while spinning.

For a stationary plant, have it spin horizontally, and build it underground.
If it does suffer a catastrophic failure, loss of life and damage to surrounding infrastructure should be minimal

Re:Seems silly to use this. (1)

simcop2387 (703011) | more than 5 years ago | (#26251929)

well as far as stationary ones go, you wouldn't have to worry about the gyroscopic effects at all, but the rest of them would be pretty close to the problems with them i would think. You'd have to build gigantic ones to be able to store enough energy, so then you get the problem of how to mount them. and then with so much mass, they'll probably end up destroying bearings pretty fast depending on how you mount them.

Re:Seems silly to use this. (3, Informative)

An Onerous Coward (222037) | more than 5 years ago | (#26252259)

The weight of a flywheel is far less important than the weight. Energy of motion is a product of mass times velocity squared, so doubling the rate of rotation quadruples the amount of energy stored. The ideal for many applications is to find a material that is very light, but won't fly apart at high speeds. I remember reading about somebody trying something with carbon nanofibers, but that was a long while back.

The weight doesn't matter much for energy seepage either. A good flywheel will be suspended by magnets, so regardless of the weight, the friction due to weight is effectively zero. There is still air friction and electrical losses to deal with.

Getting energy into them isn't a huge obstacle either. I've scoured the web, and it looks like the people actually selling flywheels-as-UPS solutions are claiming 90% efficiency.

Something may be missing in my understanding here. The article claims that the battery backup for the wind farm costs about three million dollars per MWH, whereas the flywheel backup system I'm looking at right now [vyconenergy.com] claims that it can give you about 200kWH capacity for about $50,000. That's $250k per MWH installed, and very low maintenance costs.

Their claims could be overblown, or I could have my math wrong, or there is something I'm missing that makes the flywheels unsuitable for this application. There might also be a huge economic opportunity, but somehow I doubt it.

Re:Seems silly to use this. (2, Informative)

An Onerous Coward (222037) | more than 5 years ago | (#26252291)

That first sentence was supposed to be "The weight of a flywheel is far less important than the rotation speed."

Re:Seems silly to use this. (3, Interesting)

wylf (657051) | more than 5 years ago | (#26252459)

Actually, a few Formula 1 teams are adopting a flywheel solution to implement KERS (Kinetic Energery Recovery System) for the upcoming 2009 season.

http://www.greencarcongress.com/2007/11/second-major-f1.html [greencarcongress.com]

From memory, BMW and Ferrari have opted for different technology though.

Re:Seems silly to use this. (3, Interesting)

slimjim8094 (941042) | more than 5 years ago | (#26251927)

I heard a story of a datacenter in California doing this for backup power. The center was powered off of the mains, and also had a large (20ft or so) flywheel kept running. If the power cut, the flywheel powered the necessary systems for the minute or so it took the generators to start up.

Seemed ingenious to me.

Re:Seems silly to use this. (4, Informative)

Anonymous Coward | more than 5 years ago | (#26252325)

Flywheels are attractive for short-term peak power delivery. They have low failure rates and easy fault detection (if the wheel is intact and spinning at the required speed, you know how much energy is available).

For long term loads (hours) flywheels aren't competitive with lead-acid batteries, let alone more exotic types such as the NaS battery the article describes. For example, the Active Power CSDC-500 [activepower.com] flywheel storage system supplies 50kW for 138 seconds = 1.92kWhr. The cabinet is 78" x 54" x 34" and it weighs just over 3 tons. Four long-term loads, a system with two 12V 100Ahr VRLA batteries [cdpowercom.com] would be 14" x 14" x 10" and weigh 140 lb.

A flywheel based system has nowhere near the energy density of a battery storage system. Peak power density is the flywheel's forte.

Stored (broken) wind energy (Obligatory fart joke) (-1, Troll)

dkh2 (29130) | more than 5 years ago | (#26251015)

I've got stored wind energy for you. Just visit my brother after somebody forgot and fed him chili.

ask slashdot (-1, Flamebait)

Anonymous Coward | more than 5 years ago | (#26251017)

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Re:ask slashdot (-1, Offtopic)

Anonymous Coward | more than 5 years ago | (#26251383)

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Re:ask slashdot (-1, Offtopic)

Anonymous Coward | more than 5 years ago | (#26251391)

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Re:ask slashdot (-1, Flamebait)

Anonymous Coward | more than 5 years ago | (#26251801)

Please stop fucking me in the ass.

Old idea waiting for a viable implementation (1)

Gnavpot (708731) | more than 5 years ago | (#26251051)

This is an old dream, but is has almost always been defeated by economy. And according to the article, it still is, though it is getting better:

[i]But it is expensive, costing roughly $3 million per megawatt plus millions for start-up and testing. "Right now, they're a little too expensive," Novachek says.[/i]

Looking at the numbers, it seems like a small-scale test setup. 7 MWh is not much in an 1100 MW wind turbine facility.

 

Re:Old idea waiting for a viable implementation (1)

bugi (8479) | more than 5 years ago | (#26251635)

Put back in the externalized costs, so's to compare real costs. Then we'll talk.

Re:Old idea waiting for a viable implementation (1)

hedwards (940851) | more than 5 years ago | (#26251873)

Indeed, that's one of the things which has harmed the US' production capabilities the most. We don't include those extra costs. We don't consider the cost of coal pollution when calculating the cost and it's the real reason why we need some sort of tax that companies pay when they excessively pollute. Realistically there's going to always be some consequences, but when somebody else has to pay for the damage there's no incentive to pick up the tab oneself.

Re:Old idea waiting for a viable implementation (1)

mweather (1089505) | more than 5 years ago | (#26252205)

Just imagine what we'd pay for energy is coal/oil companies had to actually pay for mineral rights instead of paying pennies on the dollar to the government.

Re:Old idea waiting for a viable implementation (1)

bavid (842765) | more than 5 years ago | (#26252545)

1100 MW is a major typo. It's a 11 MW facility.

as a sailor (1)

Markspark (969445) | more than 5 years ago | (#26251097)

i would have to say that it always blows in the day, however in the evenings and during the night there is seldom any wind.

Re:as a sailor (1)

AndGodSed (968378) | more than 5 years ago | (#26251483)

Depends on where you are.

If you stand on the shoreline here in South Africa you will find shore bound winds in the morning as the coast heats up, and sea bound winds in the evening as the shore cools down.

And this is long before/after the sun has risen/set.

In Capetown in the windy season the SouthEaster blows basically 24/7.

Re:as a sailor (4, Funny)

osu-neko (2604) | more than 5 years ago | (#26251815)

As a sailor, I'm sure your maritime experience is vast. But... do you happen to know where Minnesota is? You might want to check a map... XD

a dam sounds like a pretty good battery to me (4, Insightful)

wjh31 (1372867) | more than 5 years ago | (#26251105)

i believe some dams release water through the turbines during peak times, then pump it back up off peak at night with excess cheap electricity ready for the next day, is that not a reasonable form of energy storage? i imagine a similar level of energy storage in anything recognisable as a battery would be insanely expensive and/or involve alot of toxic chemicals

Re:a dam sounds like a pretty good battery to me (1, Informative)

Anonymous Coward | more than 5 years ago | (#26251153)

It has always been my understanding that this type of energy storage has always been the most efficient for large scale stationary energy storage. There are several implementations of similar technology that don't pollute like batteries and don't cost nearly as much for the same storage capacity.

Re:a dam sounds like a pretty good battery to me (4, Interesting)

Thundersnatch (671481) | more than 5 years ago | (#26251223)

The best places for wind turbines (open plains) are usually far away from the best places for dams (canyons). The increased cost of building transmission lines and increased losses on those lines makes your solution impractical for most locations. A few exceptions may exist, but most "wind alley" locations like TX, OK, and IA don't have the elevation changes needed for hydropower.

Re:a dam sounds like a pretty good battery to me (3, Informative)

mollymoo (202721) | more than 5 years ago | (#26251525)

Oklahoma already has two hydo plants and one pumped storage plant. You don't need huge elevation changes, a few hundred feet will do.

Re:a dam sounds like a pretty good battery to me (2, Insightful)

Thundersnatch (671481) | more than 5 years ago | (#26251673)

"A few hundred feet" is almost impossible to come by in the most ideal wind-power locations such as the I-states (Indiana, Iowa, Illinois) and west Texas. You can see the curvature of the earth in central Indiana over the corn. But as I said, there are some exceptions.

There is, I believe, one small hydro plant in Illinois, for example. One. But there are something like 40,000+ square miles of good windpower territory in Illinois. Unless you use the existing grid somehow (don't know if you can), building transmission lines to the single hydro plant would be cost-prohibitive.

Re:a dam sounds like a pretty good battery to me (2, Interesting)

carl-in-vancouver (1440373) | more than 5 years ago | (#26252383)

A few hundred feet is a lot easier to come by when you float the turbine... http://www.magenn.com/ [magenn.com] According to the site they can float it up to 1000 feet.

Wind/Water Reservoirs (2, Interesting)

copponex (13876) | more than 5 years ago | (#26251921)

In the wind alley, they do a lot of farming, right? Why not create two level reservoirs, one a hundred and fifty feet higher than the other, and then when there is excess production, you pump the lower reservoir into the higher one. Even better, find some underground features that would make it easy to create underground reservoirs with different elevations. And if you hit a hot spot of granite, even better - redirect the steam so it spins some turbines.

Drought presents problems to open air reservoirs. It may actually be cheaper to use superconducting transmission lines to somewhere with better natural features.

If WalMart and Sams Club covered all of the parking lots with solar panels, not only would they reduce localized heat effects, it would probably be enough to power all air conditioning in the south during those hot sunny days. I don't know why any sprawl areas are looking for huge plots of lands to stick solar powered plants on. They have hundreds of square miles of parking lots already, they just need to be leased from the malls and stores.

But, as always, the best way to save energy is still conservation. It's 100% effective and free. Unfortunately there's no profit in efficiency, and thus it's not a political option.

Re:Wind/Water Reservoirs (1, Interesting)

Anonymous Coward | more than 5 years ago | (#26252201)

Conservation is a stop gap at best. Unless you are planning on stopping worldwide population growth, and killing a large percentage of the worlds existing population, conservation is just a way to feel good about yourself while ignoring the actual problem. Society crippling conservation would only push the problem off on to our grandchildren instead of making our children deal with it.

Re:Wind/Water Reservoirs (1)

copponex (13876) | more than 5 years ago | (#26252421)

Society crippling conservation would only push the problem off on to our grandchildren instead of making our children deal with it.

You've confused materialism with life. Brazilians and Costa Ricans live rich lives, have less things, and use far less energy than the average American. That's doesn't mean their society is crippled, and last I checked, they were alive and not dead. They may not all lead our lifestyle, but who said sitting in traffic and working yourself to death was a high note in human development?

New energy sources need to be found, but if we had some sane zoning regulations and nationalized our transportation system, we would need far less of it. If more people recycled and checked their tire pressure and kept their air conditioner maintained, we would need less of it. If more people reduced the amount of meat they ate, bought organic and local food when they could, and stopped covering their lawns with grass instead of local plants that required zero water and zero maintenance, we would need less of it. Conservation is about planning and about feeling good, because you're doing something now to actually help the planet, instead of banking on a technological breakthrough that may not happen as soon as we need it.

I read somewhere that the world would need to be six times larger if every person ate as much beef as an American. Our lifestyle is simply unsustainable. If you want to keep ignoring this reality, you're welcome to, but your children and grandchildren won't have the luxury. They'll probably think of you, and how you complained about water restrictions, or smaller flush toilets, or hippie locavores, and think: what a jackass.

Re:a dam sounds like a pretty good battery to me (1)

rrohbeck (944847) | more than 5 years ago | (#26251351)

That's correct, but only if you have an existing dam. Building one just for storage is only viable if you have a huge height difference, i.e. a mountain.

Re:a dam sounds like a pretty good battery to me (0)

Anonymous Coward | more than 5 years ago | (#26251941)

You don't have to pump back water... you simply use less water when the wind is at maximum and you use more water when you need it.

You only have turbine with 2 time the capacity of the dam. When the wind in on, the dam go up. When the wind in off, the dam go down with more turbine power.

Simple, no pump. We already use it in Quebec.

Re:a dam sounds like a pretty good battery to me (1)

necro81 (917438) | more than 5 years ago | (#26252535)

Believe me when I say that the Dakotas and western Minnesota are no place to build a dam.

Flywheels (0)

Anonymous Coward | more than 5 years ago | (#26251109)

Modern flywheels are better than these large batteries for the short term storage of power ( ie days ) on an number of levels :(

I'd want to store it in a hydro tank... (2, Interesting)

crovira (10242) | more than 5 years ago | (#26251179)

I'd pump water UP to store the energy and let it flow DOWN to release the energy.

Granted it might not be as efficient as battery storage but it would be cheap, deploy-able right now, and it can be made as large as needed, plus it can be used to extinguish fires "downhill' and slake thirst.

It doesn't even have to be in the same place as the wind farm. Just in front of it, like in the mountains like the ones that cause the chinooks winds in Alberta.

I can see setting up a mountain top reservoir, filling it with water pumped by excess energy and emptying it when needed.

Re:I'd want to store it in a hydro tank... (5, Informative)

hypersql (954649) | more than 5 years ago | (#26251243)

They do that. It's called Pumped-storage hydroelectricity [wikipedia.org] .

Re:I'd want to store it in a hydro tank... (2, Interesting)

barfy (256323) | more than 5 years ago | (#26251281)

They do this off the Grand Coulee Dam. But they are hardly ever used, as they are only really needed when there is need for flood control, AND lack of Power Need.

There already exist these giant "batteries" and couldn't the power be utilized for things like this, rather than something new?

There seem to be a ton of places where one could use excess energy at night, that you wouldn't need a new "Battery" source.

Re:I'd want to store it in a hydro tank... (4, Interesting)

timeOday (582209) | more than 5 years ago | (#26251505)

There seem to be a ton of places where one could use excess energy at night, that you wouldn't need a new "Battery" source.

Selling a few million plug-in hybrids should help quite a bit.

It would be even better if those cars were on the Internet so they could talk to the power company. For instance if I tell my car to be charged by 8am the next day, it could negotiate with the power company to draw power whenever it is cheapest.

Re:I'd want to store it in a hydro tank... (2, Interesting)

hedwards (940851) | more than 5 years ago | (#26251909)

I know there's been some consideration to storing energy in freezers. It's not technically storing, it's more like shifting power draw from peak to off peak times allowing for the capacity to be more efficiently used.

Basically with refrigerated warehouses being set a few degrees colder off peak and being allowed to warm subtly during peak. It's always below the necessary temperature, but the cooling system is off during large chunks of the peak consumption hours.

Re:I'd want to store it in a hydro tank... (1)

slim (1652) | more than 5 years ago | (#26251371)

I'd pump water UP to store the energy and let it flow DOWN to release the energy.

This is already mainstream technology. Traditionally it was used as a buffer between a constant power source (e.g. coal fired power station) and a variable demand (pesky consumers).

But it's not a big step to use the same technology to buffer between a variable source such as wind, and a variable demand.

OTOH I'm sure I've read statements by proponents of wind power stating that on a grid as large as the UK's (and the UK's not that big), drops in wind in one part of the country would almost always be compensated for by other parts of the country.

Re:I'd want to store it in a hydro tank... (2, Informative)

ionix5891 (1228718) | more than 5 years ago | (#26251479)

they do that here in Ireland [wikipedia.org]

ive been at the facility few years back, quite impressive engineering stuff (for a small country)

Re:I'd want to store it in a hydro tank... (1)

Icculus (33027) | more than 5 years ago | (#26251619)

There aren't a lot of mountains or really any kind of elevation changes in SW MN (where most of the wind turbines are) so that means towers or some other method of creating elevation. I'm guessing you'd need either many small tanks or some really really huge ones to store any measurable amount of energy. Maybe there's some way the water storage could be built into the turbine's tower to save on costs. Like some others have said, this works best for places with some hills or mountains.

Alternative storage medium using water (1)

schwit1 (797399) | more than 5 years ago | (#26251183)

MIT's Daniel Nocera is working on fuel cells and solar power [blogspot.com] as the energy storage, if the economics can be worked out.

How about Hydrogen (0, Redundant)

similar_name (1164087) | more than 5 years ago | (#26251195)

Could you store the energy by splitting water and storing the Hydrogen? When you burn it back you'd also have some pretty clean water. I don't know what expense is involved large scale, but it could also serve as a step to the oft talked about Hydrogen economy.

Re:How about Hydrogen (1)

GeckoAddict (1154537) | more than 5 years ago | (#26252309)

I could swear that was a movie [imdb.com] ...

Gasp! (-1, Flamebait)

Anonymous Coward | more than 5 years ago | (#26251207)

Using batteries to store electricity!? What a wild idea! What will they think of next... Some sort of cylindrical container for holding liquids one intends to imbibe?

Re:Gasp! (2, Funny)

similar_name (1164087) | more than 5 years ago | (#26251255)

Some sort of cylindrical container for holding liquids one intends to imbibe?

You'd better patent that before someone else does.

batteries? (1)

buddyglass (925859) | more than 5 years ago | (#26251211)

Batteries need to be replaced, and are composed of a number of undesirable chemicals. Seems like ultra-capacitors might be of use here. Several orders of magnitude more recharge cycles and generally safer. Portability isn't an issue, so they could be as big and heavy as needed.

Re:batteries? (1)

rrohbeck (944847) | more than 5 years ago | (#26251417)

LOL. 1 MWh = 3.6 GJ. An ultracapacitor stores a few J max so you'll need about a billion of them.

Re:batteries? (1)

buddyglass (925859) | more than 5 years ago | (#26252435)

According to this article (which may or may not be accurate- I don't know enough to say):

http://www.batteryuniversity.com/partone-8.htm

The gravimetric energy density of super-capacitors is approximately 1/5 to 1/10 that of traditional batteries. That is to say, on the order of 1 to 10 Wh/kg. The original article says the array in Minnesota is designed to store 7 MWh. So, to store that much energy in a super-capacitor, assuming the energy density figures from that link are correct, the device would need to weigh from 700k to 7 million kg.

I'm not sure exactly how much space that would consume, but we can perhaps estimate. We'll assume the density of a fairly light metal. Say, aluminum, which has a density is 2.7 g/cm^3. So a 700,000 kg super-capacitor would need 260 million cm^3 of space. We'll assume a normal building height of 4 m (400 cm). This means that the "optimistic" super-capacitor (10 Wh/kg) could be housed in an enclosure that is 8m x 8m x 4m. The "pessimistic" super-capacitor would need a 25m x 25m x 4m enclosure.

If the technology scales linearly, space doesn't seem to be an issue. Cost, however, probably is.

Re:batteries? (1)

causality (777677) | more than 5 years ago | (#26251469)

Batteries need to be replaced, and are composed of a number of undesirable chemicals. Seems like ultra-capacitors might be of use here. Several orders of magnitude more recharge cycles and generally safer. Portability isn't an issue, so they could be as big and heavy as needed.

There is one question I have about supercapacitors and you'd think it would be one of the most basic things about them, yet I have never seen an answer to this. Capacitors, at least the few I have seen, generally want to release their stored energy all at once. How is this addressed when supercapacitors are used? For example, let's say you have a supercapacitor that can power a light bulb for eight hours. How do you make it actually provide a lower current over those eight hours instead of providing all of that energy in a single instant and frying the bulb?

Re:batteries? (0)

Anonymous Coward | more than 5 years ago | (#26251529)

Perhaps use a superresistor.

Re:batteries? (2, Informative)

Timothy Brownawell (627747) | more than 5 years ago | (#26251609)

Capacitors, at least the few I have seen, generally want to release their stored energy all at once. How is this addressed when supercapacitors are used? For example, let's say you have a supercapacitor that can power a light bulb for eight hours. How do you make it actually provide a lower current over those eight hours instead of providing all of that energy in a single instant and frying the bulb?

By understanding I=V/R [wikipedia.org] .

A capacitor has a certain voltage (whatever you charged it to) and an internal resistance. The load (light bulb) you attach also has a certain resistance. The discharge rate is determined by those two resistances (added together) and the voltage. The "all at once" just means that the internal resistance is almost zero, so if you connect a load that also has zero resistance the capacitor will discharge very quickly. If your load doesn't have near-zero resistance, there won't be any real difference from using a battery.

Re:batteries? (0)

Anonymous Coward | more than 5 years ago | (#26251717)

You don't provide a current. The capacitor is charged to a certain voltage, and the current will depend on the resistance of the connected load (the light bulb). Connect a "smaller" bulb, it will have a higher resistance, so there is less current (voltage is the same), so it will take longer for the capacitor to be drained.
Like a water tap: the pressure in the pipes is the same, but you can make a smaller flow by opening the tap just a little.
Super capacitors are no different from normal capacitors, other than that they can store a relatively large charge in a physically small
capacitor. (but still less than a real battery)
There main advantage over batteries is a very low internal resistance which makes very high current possible (when you need it), like for charging in seconds, or for supplying short peak loads.

Re:batteries? (1)

Firethorn (177587) | more than 5 years ago | (#26251587)

At least those undesirable chemicals are pretty much 100% recyclable. For energy storage like this, you need two things. It needs to be cheap per kwh, keeping in mind maintenance and longevity. Efficiency is also huge - a few points of efficiency can make all the difference, cost wise. Still, a lesser factor than cost, especially when you're simply looking at recovering power that would otherwise not be used.

NiMH is around 66% efficient charge wise, LiIon, though twice as expensive(at this time), is 99.9% efficient.

The extra efficiency would make a huge difference - not so much in the cost of the batteries, but in how many turbines you need to build.

Looks like LiIon is in the same magnitude at durability, ~1200 cycles vs ~1000, assuming excellent battery management, which the power companies would presumably do.

Hmm... Cheap 18650 LiIOn battery [batteryjunction.com] 2.4Ah, 3.7V, 8.88 Wh, $5. $.56 per Wh (not suitable for usage in nonsmart charging systems)
Protected 18650 batteries [batteryjunction.com] 2.6Ah, 3.7V, 9.62 Wh, $6.69 ea/500+. $.70/Wh

Gotten a LOT cheaper.

Still, Industrial NiMH [batteryjunction.com] , 2.1Ah, 1.2V, 2.52Wh, $1.45/500+. $.57/Wh

No wonder so many devices have switched to LiIon!

Still, you're looking at $560-700 for a battery pack to store/distribute $.10 of electricity. Assuming full charge and discharge daily, that's $36.50 of electricity using today's retail prices in my area, but a THIRD of the battery's lifespan. $110 of electricity for the pack's life.

Sigh... Back to the problem with electric vehicles. We 'only' need lithium ion batteries to be around an order of magnitude cheaper to be economical.

Store the energy in a massive weight (4, Interesting)

smartin (942) | more than 5 years ago | (#26251241)

I don't know if this is feasible but I've always thought that a mechanical solution would be better. Use the excess energy to lift a huge weight like the weights on a pendulum clock. When the wind dies down, just let the weight power a generator. Assuming concrete is reasonably environmentally friendly this would be a pretty clean solution.

Just do the math (1)

rrohbeck (944847) | more than 5 years ago | (#26251367)

That's being done... with millions of tons of water.
Millions of tons of concrete would be slightly more difficult to handle.

Re:Just do the math (1)

cparker15 (779546) | more than 5 years ago | (#26251515)

While we're at it, we should find a way to fit a piezoelectric generator into the picture.

Re:Just do the math (2, Insightful)

theguyfromsaturn (802938) | more than 5 years ago | (#26251599)

Why concrete? Cement is ridiculously energy intensive to produce. Why not stick with water, or if you really want something more complicated to handle but heavier, go with good ol' rock. We'll need to conserver all the cement and steel that we can in the coming years.

Re:Just do the math (1)

smartin (942) | more than 5 years ago | (#26251725)

I figured concrete was heavier than water, but even just wet sand might be good if you can contain it.

Re:Store the energy in a massive weight (0, Flamebait)

Ceriel Nosforit (682174) | more than 5 years ago | (#26251423)

Flywheels. Flywheels are developing country compatible. The high-tech flywheel solution is making a small weight spin very quick, but that's only a good idea for mobile applications. For stationary applications you want a very big weight spinning 'slowly' so that you can use low precision manufacturing methods. You could probably build this out of old cars and a ton (metric) of cement and have teriffic results.

There's a business idea for anyone with... well, business acumen alone. Buy up scarp cars and scavange the parts to build flywheels for industrial scale energy storage. Hire Mexicans or something and market yourself as a green company.

Re:Store the energy in a massive weight (3, Informative)

slim (1652) | more than 5 years ago | (#26251451)

Assuming concrete is reasonably environmentally friendly this would be a pretty clean solution.

Concrete has a massive carbon footprint. The calcination of lime releases a lot of CO2, on top of the fossil fuels used in manufacture and transport.

Re:Store the energy in a massive weight (1)

SagSaw (219314) | more than 5 years ago | (#26251533)

Use the excess energy to lift a huge weight like the weights on a pendulum clock. When the wind dies down, just let the weight power a generator.

Something like this? [wikipedia.org]

Re:Store the energy in a massive weight (1)

hcdejong (561314) | more than 5 years ago | (#26251563)

Well, to give you an idea of the weight and height needed:
Dinorwig (a large pumped storage plant in the UK) uses 390 m^3 of water per second and has a water column of 570 m above the turbines to produce 1800 MW.
So they're using 1.4 million m^3 of water an hour.
Now a mechanical solution would work differently, but I'd be surprised if 1.4 million tons suspended at 570 m height was not within an order of magnitude for a pendulum storage system that can produce 1.8 GWh. That's quite a lot of weight to be hoisting that high.

Re:Store the energy in a massive weight (3, Informative)

An Onerous Coward (222037) | more than 5 years ago | (#26251965)

I did some calculations (yay!), and came up with the following: Raising the Empire State Building (365,000 tons of material) to the height of one meter would store a little shy of a megawatt hour of energy.

I'm imagining this weird future city where the buildings slowly rose and fell as energy was stored and withdrawn. It's a cool thought, but it seems that the engineering difficulties would be considerable, and the payoff not so much.

A system where water was stored at the top of a skyscraper might be more feasible (putting the weight a hundred times higher means you only need 1% of the material. You might be able to do something with water, or a block on a chain. But the storage payoff seems relatively small.

It might make more sense to deal with material that's already being lifted up and dropped down. Like integrating some sort of storage and release system for the water already being pumped to the top of skyscrapers. Given separate reservoirs for potable water and sewage, and some leeway about when to pump water in and release waste out, something might be arranged.

The calculation: 365000 tons * 907 kg/ton * 10 joules/kg * 1kWH / 3,600,000 joules. The 365000 tons figure is from this kid's site [esbnyc.com] .

Re:Store the energy in a massive weight (1)

invisiblerhino (1224028) | more than 5 years ago | (#26252007)

Not sure why but I read the title of that post as "Store the energy in a massive virgin".

What's wrong with Flywheels? (1)

grumpygrodyguy (603716) | more than 5 years ago | (#26251393)

Flywheel energy storage [wikipedia.org]

"Applications

Uninterruptible power supply

Flywheel power storage systems in current production (2001) have storage capacities comparable to batteries and faster discharge rates. They are mainly used to provide load leveling for large battery systems, such as an uninterruptible power supply for data centers.[9]

Flywheel maintenance in general runs about one-half the cost of traditional battery UPS systems. The only maintenance is a basic annual preventive maintenance routine and replacing the bearings every three years, which takes about four hours.[5]"

how about... (0)

Anonymous Coward | more than 5 years ago | (#26251395)

an huge hydrogen tank?

wasn't this what they say? that hydrogen may not be efficent to produce, but it's a hell of a battery?

Reasonable? (1)

D_Blackthorne (1412855) | more than 5 years ago | (#26251415)

Looks like batteries of this design are on a par energy-density-wise with Lithium-Ion, and have an estimated life-span of 15 years (although I couldn't find a charge-discharge cycle figure). How expensive are these to produce compared to other chemistries, I wonder?

Some of you are discussing using a flywheel. Does anyone have some data on the efficiency of that technology versus using this type of battery? My first thought would be that coming up with bearings for a flywheel that can handle the mass of the wheel yet be as close to frictionless as possible would be difficult and expensive to develop and then later to maintain.

Re:Reasonable? (1)

Timothy Brownawell (627747) | more than 5 years ago | (#26251481)

My first thought would be that coming up with bearings for a flywheel that can handle the mass of the wheel yet be as close to frictionless as possible would be difficult and expensive to develop and then later to maintain.

Use the same tech they make maglev trains with, and put the whole thing in a big shell you can pump all the air out of.

Re:Reasonable? (1)

bugi (8479) | more than 5 years ago | (#26251675)

They already have those huge spinning things. Why not just enclose them and suck out all the air?

Re:Reasonable? (1)

mangu (126918) | more than 5 years ago | (#26251937)

My first thought would be that coming up with bearings for a flywheel that can handle the mass of the wheel yet be as close to frictionless as possible would be difficult and expensive to develop and then later to maintain.

No, that's old stuff, no problem at all [google.com]

Pros/Cons of potential energy storage? (1)

gsgriffin (1195771) | more than 5 years ago | (#26251565)

As I read this about batteries, I'd love for someone with a lot more experience and knowledge to chime in on potential energy storage as opposed to these chemical/electrical? I would assume it to be a lot less expensive to build/install and maintain over the long term to have the wind (for example) pump water up a tower and then use gravity and water the water coming down to generate electricity. Seems like using the wind to create potential energy could be cheaper (and simple) if we had some ingenious concepts working on that. It would also be better for exporting to real polluting nations like India and China.

Re:Pros/Cons of potential energy storage? (1)

Scannerman (1136265) | more than 5 years ago | (#26252541)

Pumped storage is used quite widely, but you need a LOT of capacity to make it work - say a lake of a few hundred acres with a few hundred feet elevation before the engineering becomes economic.

This would not be economic to create artificially - so it is limited to locations where the geography is suitable

How efficient? (1)

hcdejong (561314) | more than 5 years ago | (#26251627)

Pumped storage is about 60-70% efficient, I wonder how this compares?

How manageable are large battery banks? (1)

hcdejong (561314) | more than 5 years ago | (#26251655)

In my limited experience of using battery banks (2-4 AAs or Cs in series or parallel), the most common cause of failure is having them in series while charging: small changes in cell chemistry mean that the batteries in a pack don't discharge at the same rate, so when you start charging one battery is at 0% and the other at 20%. This kills the battery that was at 0%. Battery life is extended greatly if you charge every cell individually instead of putting them in series (as most home-grade battery chargers do).

From the diagram, it looks like each module contains hundreds of cells, with the cells connected by busbars. Looks like a recipe for failure to me. What's the secret?

Re:How manageable are large battery banks? (0)

Anonymous Coward | more than 5 years ago | (#26252157)

Constantly switch a capacitor between all the cells in the series.

It will take power from the higher voltage cells and charge up the lower voltage cells.

It would be easy with 2-4 cells, but might not be practical with hundreds of cells.

Buy a prototype from EEstor! (1)

LordKazan (558383) | more than 5 years ago | (#26251661)

Use that.. 54 megawhat hours of storage

Re:Buy a prototype from EEstor! (1)

Dr_Barnowl (709838) | more than 5 years ago | (#26252127)

54 kWh.

But not such a silly idea.

These are 7MWh sodium-suplhur units, with a 1MW output capacity. You'd only need 135 EESU units to match it. A vaguely half-remembered stat puts it's production cost per piece at around $4000, which puts a 7MWh unit at a mere $540,000 ; a snip compared to the $1M dollars for these sodium-sulphur things, without the tribulations of operating at 700 degrees C.

Re:Buy a prototype from EEstor! (1)

LordKazan (558383) | more than 5 years ago | (#26252347)

oh right kWh not mWh! my bad!

but yeah.. still cheaper

Ultra-caps instead of sodium-sulphur storage (1)

macraig (621737) | more than 5 years ago | (#26251707)

If ultra-capacitors become something more tangible than vaporware, I can see this approach becoming much more viable. As it is, with the hidden costs to the environment and economy of chemical batteries, the actual cost-benefit ratio here is a bit more murky, I think.

Something is wrong here... (0)

Anonymous Coward | more than 5 years ago | (#26251759)

The summary says:
"The company is currently trying it in a 1,100 megawatt facility of wind turbines in Southern Minnesota."
while Sciam says:
"Winter winds howl off the Dakota prairie through Minnesota, turning the 1,100 megawatts worth of wind turbines in Xcel Energy's system in that state."
These guys, especially the submitter seem to imply that a 1100 MW wind facility exists... I don't know of any wind facility of this size, plus, according to the company (http://www.xcelenergy.com/Company/AboutUs/Pages/Temp.aspx) they only have 25 MW of installed wind power... just wondering...

Re:Something is wrong here... (1)

osu-neko (2604) | more than 5 years ago | (#26252003)

Xcel's total wind power generation has been well over that for many years. (I remember reading about them going over 500 MW a few years ago, although I can't find the source now.) However, Xcel doesn't actually own most of the wind facilities is uses. The one 25 MW facility listed on the page you linked to is probably the only one they wholly own and operate themselves.

1,100 Megawatts? (3, Funny)

emandres (857332) | more than 5 years ago | (#26251783)

1,100 megawatts, eh? Why, that's almost 1.21 gigawatts! Now we just need to come up with a flux capacitor and find an old Delorian!

Gosh, using batteries. What a novel idea! (0)

Anonymous Coward | more than 5 years ago | (#26251871)

Gosh, how about that. Using batteries to store excess electricity (instead of disconnecting currently unused towers). Or even better than that (as one engineer pointed out) using brakes to slow the turbines to match line generation 60 cycle power (I'm serious about the last one). My idea was always to electrolyze water (into hydrogen and oxygen in a large cell), and when needed use a fuel cell to turn it back into electricity (DC), then use a precision dc-ac converter and a phase-locked-loop circuit to match power line frequency exactly. Why batteries and other long-term storage solutions have not been used up to this point is absolutely baffleing.

God damnit! (0)

ZosX (517789) | more than 5 years ago | (#26251979)

I thought Roland was gone for good!

Its pretty bad when 80% of what I read here I saw on Digg 4 days ago......

Re:God damnit! (2, Funny)

AbRASiON (589899) | more than 5 years ago | (#26252475)

Yeah, but the comments here don't make me want to kill people.

Why not decentralise these batteries? (1)

Teun (17872) | more than 5 years ago | (#26252037)

When we put the batteries at the consumer end we have only half the transmission losses, compare to a distributed system like bittorrent.
Now the world seems to embrace the electric car these can, as long as they are connected to the charging point, be excellent buffers for excess energy.

Re:Why not decentralise these batteries? (1)

Dr_Barnowl (709838) | more than 5 years ago | (#26252469)

Batteries at the consumer end with local microgeneration would have transmission losses closer to zero, for charge used locally.

Of course, large centralized projects are more attractive to the pocketbooks of Big Energy.

Another idea (1)

Omnifarious (11933) | more than 5 years ago | (#26252255)

Generate hydrogen and release the energy back using a fuel cell.

Though, I like the distributed storage system idea better. I think that will actually lead to better battery technology faster than almost any other system.

One of several promising technologies (0)

Anonymous Coward | more than 5 years ago | (#26252563)

This is an important test of the scaling of sodium sulphur battery technology. The price might be high but it is simple enough and uses cheap and relatively environmentally safe materials. I am optimistic about the ability to bring the cost down. The vanadium battery like fuel cells is still reliant on expensive and inefficient ion exchange membranes and toxic vanadium which may not be readily available in large quantities. Pumped hydro is great when it is already near where you would like a battery.
Energy storage technologies can also help us get a better return on our investment in transmission lines.

I like to see advances in battery technologies. It gives a lot more options in transportation, transmission, energy security and flexibility for green energy.

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