WIND BATTERY: This series of sodium-sulfur batteries will store wind power in an attempt to both make it more reliable and cheaper.
Image: Courtesy of Xcel Energy
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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. By 2020, the utility expects to more than triple that amount in a bid to avoid more polluting energy sources. But the wind doesn't always blow and, even worse, it often blows strongest when people aren't using much electricity, like late at night.
So Xcel Energy, Inc., has become one of the first utilities in the U.S. to install a giant battery system in an attempt to store some of that wind power for later. "Energy storage might help us get to the point where we can integrate wind better," says Frank Novachek, director of corporate planning for the Minneapolis-based utility with customers in Colorado, Kansas, Michigan, Minnesota, New Mexico, the Dakotas, Oklahoma, Texas and Wisconsin. "The overall cost of electricity might be lower by using energy storage."
The energy storage in question—a series of sodium–sulfur batteries from Japan's NGK Insulators, Ltd.—can store roughly seven megawatt-hours of power, meaning the 20 batteries are capable of delivering roughly one megawatt of electricity almost instantaneously, enough to power 500 average American homes for seven hours. "Over 100 megawatts of this technology [is] deployed throughout the world," Novachek says. The batteries "store wind at night and they contract with their utility to put out a straight line output from that wind farm every day."
That removes one of the big hurdles to even broader adoption of wind power: so-called intermittency. In other words, the wind doesn't always blow when you want it to, a problem Texas faced earlier this year when a drop in wind generation forced cuts in electricity delivery. But with battery backup, the 11-megawatt wind farm outside Luverne, Minn., can deliver a set amount of electricity at all times, making it more reliable or, in industry terms, base-load generation. Plus, the battery effectively doubles the wind farm's output at any given moment—both the megawatt being produced by the wind farm itself (that would otherwise have gone to charging the battery) and the megawatt delivered by the battery.
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. But "it's getting in the ballpark where it looks like the economics might be there. Testing will help us understand the value."
So far the battery has been through five charging and recharging cycles and testing will continue through next year, Novachek says. Other utilities, including the Long Island Power Authority in New York State and American Electric Power in Ohio, have used similar or the same batteries to better manage their grids, but this would represent the first battery to store wind power in the U.S.
The battery is not the only storage experiment Xcel Energy is running: It has been testing using electricity from wind and solar installations to generate hydrogen and then burn the hydrogen in a generator to turn it back into electricity when as needed. And the utility has paired with the city of Boulder, Colo., to test plug-in hybrid electric cars as a means of providing electricity during the day when people are at work and not driving.
"The Midwest is a great [wind] resource and we are strategically placed to use that and reduce our carbon footprint," Novachek notes, by replacing some of the 16 coal-fired plants and 28 natural gas power plants the company now operates. "New technologies that are out there might really help us get more green than people had hoped—and energy storage is one of those."
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31 Comments
Add CommentIs Sci Am saying that these batteries will not work for Solar or some other kind of power generation?
Reply | Report Abuse | Link to thisWhy not use the electrical potential in slack times for electrolysis and liquidification ( compression) of the resultant by products of hydrogen and oxygen. This could be used in fuel cells, or used as fuel in internal combustion engines. It is easy to store with existing technology, is efficient in producing energy in many forms (mechanical and electrical) and is pollution free.
Reply | Report Abuse | Link to thisOpps, sorry. That is what you get for not reading an entire article before jumping in.
Reply | Report Abuse | Link to this"Plus, the battery effectively doubles the wind farm's output at any given momentboth the megawatt being produced by the wind farm itself (that would otherwise have gone to charging the battery) and the megawatt delivered by the battery."
Reply | Report Abuse | Link to thisOoooh, they've discovered how to bypass the 2nd law! Just charge the battery once, and run at double your power output forever!
It's pathetic to see SA, whom we assume understands basic physics take any of this "green" energy seriously. We're excited because a utility can power 500 homes?!?
Vanadium Redox Flow Batteries have been around a while now and have proven to be very effective at balancing the load from wind farms. I'm not sure what advantage these batteries have?
Reply | Report Abuse | Link to thisSouth Dakota has two Hydroelectric dams on the Missouri River. Why not balance the power output of the dams with the output of the windfarms. Storing water is easier than storing electricity.
Reply | Report Abuse | Link to thisClarification, please. The article says the cost would be "$3 million per megawatt," but crucial info is missing. Is that a megawatt of nameplate (maximum) capacity, or annual average capacity? It makes a big difference -- a factor of three or four.
Reply | Report Abuse | Link to thisFrom what I understand, which may be wrong.. But they are trying to get away from hydroelectric dams and they have and will continue to cause damage to the environment.
Reply | Report Abuse | Link to thisAnd even so, the amount of work and energy used to create a hydroelectric dam is much greater, and cost so much more money than a wind farm. The electricity would cost more coming from the dam vs the wind farm.
Another boon-doggle: a wind-farm that generates 1,100 Megawatts: I wonder just how many gigawatt fossil-fuel fired power plants we have in operation? An article in the New York TImes this past summer gave the PEAK demand supplied by ConEd - our local power company - as just under 17,000 Megawatts. This does not include the power supplied from several co-gen operations here in the Big Apple. ConEd is, by law required to provide back-up for these operations.
Reply | Report Abuse | Link to thisAnd this also doesn't begin to cover the demands of surface transit: buses, taxis, delivery vehicles, etc.
Collin
Reply | Report Abuse | Link to thisThe cost per kw of electricity from a hydroelectric dam (depends upon the size) is $1200 to $2000/kw without tax credits. The latest costs I have on wind generators is $2000/kw from Otter Tail Power with "tax credits" (May 2008). Maintenance costs for wind generators range from 1 to 5 cents/kw; maintenance costs for hydroelectric plants are 0.5 cents/kw. The estimated lifetime of a wind generator installation is 25 years; the estimated lifetime of a hydroelectric plant is 75 to 100 years. (verified by older existing plants.)
Large reservoir hydroelectric plants may cause damage to the environment if they are not well thought out. However, there are 80,000 existing dams in the U.S. utilized for flood control, irrigation, navigation, municipal water supplies, etc; and only 3% of these dams are used for electrical power generation (Reference Hydro Review magazine, Sept 2006 issue, "National Inventory of Dams"). That means that if we had some federal impetus to utilize some of the "existing" dams, we could generate 30,000 MW of additional electrical power (15,000 two MW wind generators which no one wants in their backyard) without building any new dams. This cost per KW would range in the $500 to $800/KW range as you do not need the funds for the dam.
In addition, there are many run of river hydro installations that do not require reservoirs. For example, my old firm (I am retired) is now installing 300 MW of run of river powerplants on the Ohio River at existing lock & dams. The installations require no reservoir, and just utilize the natural flow of the river. This could be replicated on a number of the U.S. rivers that have existing lock & dams.
In summary, hydroelectric power is less expensive to install than wind power; it has lower maintenance costs over the life of the facility; and the hydroelectric installation has a longer life.
Another interesting option for large batteries is for distributed power storage for load smoothing. If each neighborhood had a battery pack that could supplement on-line power generation, we could drastically reduce the need for expensive, peak power generation. This would also be a boon for "homeland security" as it would greatly reduce the risk of cascading power failures when one section of the grid goes down temporarily.
Reply | Report Abuse | Link to thisI am so tired of science writers who mess up the story because they don't understand the units of energy and power.
Reply | Report Abuse | Link to thisThe article says the batteries store 7 megawatt hours. Fine. Then it goes on to say "meaning the 20 batteries are capable of delivering roughly one megawatt of electricity almost instantaneously" what the H does that mean. Power, measured in megawatts is by definition an instantaneous unit. What's with "almost instantaneous".
Then the article says, "Over 100 megawatts of this technology [is] deployed throughout the world," Huh? Battery capacity is measured in megawatt-hours, not megawatts.
Then the article says, "costing roughly $3 million per megawatt" same thing. Battery cost must be proportional to megawatt-hours, not megawatts.
If the idea is to make a battery with 24 megawatt-hours of capacity able to deliver 1 megawatt of power uniformly for 24 hours, then say so.
Shame on Sciam writers and double shame on Sciam editors for not mastering such basic units in an article about energy.
I am so tired of science writers who mess up the story because they don't understand the units of energy and power.
Reply | Report Abuse | Link to thisThe article says the batteries store 7 megawatt hours. Fine. Then it goes on to say "meaning the 20 batteries are capable of delivering roughly one megawatt of electricity almost instantaneously" what the H does that mean. Power, measured in megawatts is by definition an instantaneous unit. What's with "almost instantaneous".
Then the article says, "Over 100 megawatts of this technology [is] deployed throughout the world," Huh? Battery capacity is measured in megawatt-hours, not megawatts.
Then the article says, "costing roughly $3 million per megawatt" same thing. Battery cost must be proportional to megawatt-hours, not megawatts.
If the idea is to make a battery with 24 megawatt-hours of capacity able to deliver 1 megawatt of power uniformly for 24 hours, then say so.
Shame on Sciam writers and double shame on Sciam editors for not mastering such basic units in an article about energy.
I am so sick of science writers who mess up the story because they don't understand the units of energy and power.
Reply | Report Abuse | Link to thisThe article says the batteries store 7 megawatt hours. Fine.
Then it goes on to say "meaning the 20 batteries are capable of delivering roughly one megawatt of electricity almost instantaneously" what the H does that mean? Power, measured in megawatts is by definition an instantaneous unit. What's with "almost instantaneous". The rate of discharge of a battery MW is unrelated to its storage capacity MWh.
Then the article says, "Over 100 megawatts of this technology [is] deployed throughout the world," Huh? Battery capacity is measured in megawatt-hours, not megawatts.
Then the article says, "costing roughly $3 million per megawatt" same thing. Battery cost must be proportional to megawatt-hours, not megawatts.
If the idea is to make a battery with 24 megawatt-hours of capacity able to deliver 1 megawatt of power uniformly for 24 hours, then say so.
Shame on Sciam writers and double shame on Sciam editors for not mastering such basic units in an article about energy.
anorlunda
Reply | Report Abuse | Link to thisThe 3 million per MW is a correct value as stated. This is the installed cost of the facility, and is comparative to what we used in our estimates for hydroelectric plant installed costs. Hydro plants cost $1200 to $2000/kw installed vs the wind generator's $2000/kw installed with tax credits; and this batteries installed cost of $3000/kw (or $3 million per MW)
The kwhr production of a hydro plant is based upon the % of operating time; and the total KW installed. For example, a 100 MW hydro plant that operates at a 80% capacity factor (capacity factor is based upon the amount of water available to run the plant) would produce annually (100,000KW) x (80%) x (24 hr/day) x (365 days) = 700.8 million kwhrs. A wind generator of 2 MW with a 20% capacity factor (runs only 20% of the time) would produce annually (2000 KW) x (20%) x (24 hr/day) x (365 days) = 3.5 million kwhrs.
You missed something very, very basic.
Reply | Report Abuse | Link to thisThe big deal isn't that they can discharge the battery forever, it's that they can discharge the battery AND use the wind power simultaneously to cover for dips in power availability.
The subtitle of this article says that these batteries will make wind energy cheaper. How can that be, if they cost $3 million per megawatt? Wind turbines already cost $2 million per installed megawatt. If the batteries are added to correspond with the average annual output of a facility, they would add $1 million per installed megawatt, a 50% increase in cost. If they are to be added to absorb the full capacity, that would be a 250% increase in cost.
Reply | Report Abuse | Link to thisNot to mention the additional massive construction: Would Xcel's present 1,100-megawatt wind plant require 350 of the huge structures shown in the photo?
It would also be interesting to know how much energy is lost in the storage, thus cutting into wind's already low average output.
And I second frgough's criticism of this report's statement that the batteries will double a facility's output. Magic!
Or if they in fact cost $3 million per megawatt-hour, then this little test set-up actually costs over $22 million. It would nice to have some real figures.
Reply | Report Abuse | Link to thisSome questions about the :
Reply | Report Abuse | Link to this-high price of the batteries (3 m $ / Mwh )
-low energetic efficency of storage (just 50% of the power is recovered )
-short lifetime of batteries ( about 1000 cycles = about 3 years )
We, nemes-invent srl , developed a new technology based upon our patented "Active Energy Storage" and the "Regenerative Isotherme",using compressed gases ,low priced, high efficient ( about 100%) and at least 10 years lasting.
Do not waste your money to purchease such expensive toys as electric batteries.
Ion G Nemes
nemes.invent@gmail.com
The electric wind energy storage is a very expensive matter.
Reply | Report Abuse | Link to thisThe batteries last just 1000 cycles, have a small energetic efficiency and cost a lot.
Our newest patented "Active Energy Storage" procedure based upon the"Regenerative Isotherme" last at least 10 years, has a 100% efficiency and is relativ cheap to put in service.
Do not waste your money to buy electric batteries for wind energy storage.
Ion G Nemes
nemes-invent srl
nemes-invent at 12:26 PM on 12/30/08
Reply | Report Abuse | Link to thisDo not waste your money to buy electric batteries for wind energy storage.
Redox flow batteries such as produced by VRB Power systems have no limits to charge/discharge systems.
http://www.vrbpower.com/docs/media/20060409%20-%20Toronto%20Star%20-%20Storage_The%20Next%20Generation.pdf
I have less faith in Sodium Sulfur batteries and question their use.
As to 'regenerative isotherm', I have seen no reference to it and you provide none. This is a form of efficient gas compression?
http://www.bit.or.at/irca/bbsshow8.php?ref1=06%20RO%20RIAP%200GGA&vQuelle=ECO&cc=
nemis-invent
Reply | Report Abuse | Link to thisA number of your statements seem bogus. No energy storage system has 100% efficiency. This efficiency rate is both theoretically, and of course, practicaly impossible. Hydroelectric pumped storage has a 72% round trip efficiency for energy storage from the potential energy of the stored water to electricity; and this is the highest efficiency of any energy storage system. (Reference "Hydropower Engineering Handbook" by John Gulliver, Roger Arndt, Mcgraw- Hill, 1991, page 11.26) Moreover, if your scheme is in any way related to compressed air energy storage, you are talking in the range of 55% efficiency because of the loss of heat that occurs when you compress the gas.
Do you have any references for your process; or is this just more hot air?
nemes-invent - Did you pay Sci Am for running your advertisement post? You are a digusting parasite.
Reply | Report Abuse | Link to thisThere are plenty of companies looking into battery storeage for power. So far I am not aware of much success on a practical level. I am far more interested in the potential of the super capacitor work being done. If carbon nano-sheet capacitors actually work as theorised and can be manufactured on a large scale they will replace batteries fairly effectively.
Thank you for replay.
Reply | Report Abuse | Link to thisAny kind of electric batteries is very expensive, 50% storage efficiency and just 1000 cycles useful life. Every 2 -3 years must be renewed. The storage price is hugh and must be added to the energy cost per kWh..
Our "Active Energy Storage technology by contraries , has 100% efficiency
last at least 10 years and is not so expensive.
Ion G Nemes
With all wind power generated is consumed, doesn't it decrease the remaining wind power available for global cooling?
Reply | Report Abuse | Link to thisIn the same vein of thought, doesn't those vast solar power farms create perpetual shadows to prevent any thing from growing?
Can they convert wind power to compressed air? With convenient outlets to adjust tire pressure ,so as to increase mileage?
Reply | Report Abuse | Link to thisHas anyone forgotten an enormous and endless source of wind power available to all Americans Can you say... Congress?
You make a great argument for Dams over wind power but another idea is to use dams rather than batteries. Batteries are expensive and inefficient. One of the limiting factors on production of hybrid cars is the availability and cost of batteries. If we start using batteries to store wind generated electricity it will impact the cost of batteries for cars etc.. Not to mention the fact that the battery plant that produces batteries for the Prius has caused a local environmental disaster with its waist. If there are periods of excess electricity production from wind or any other source a better way to store the power would be to pump water up hill to another reservoir and the run it through the hydroelectric plants a second time during periods of low wind electricity production. Again we may not have to build any more dams we can just use excess power to recycle hydro power. If there are no reservoirs available you can pump ground water into tanks during periods of high wind production and let it flow through turbine back into the water table during times of low wind production. This requires no new technology.
Reply | Report Abuse | Link to thisWhy not use hydroelectric power storage. During periods of peek electricity generation (from wind or any other source) water can be pumped uphill (to existing reservoirs, water tanks, or new reservoirs, etc). Then when power production is low your produce hydroelectric power. This can be accomplished on a major scale by pumping water from reservoirs at low elevation to other up hill. If you want distributed power you can install hydro-electric generators on the water supply in every municipality. All municipalities store water at elevation (on hills, water towers, on top of buildings etc). During times of high energy generation we pump water up hill and max water tanks and run it to lower tanks during low power production times. If there are no reservoirs available you can pump ground water into tanks during periods of high wind production and let it flow through turbine back into the water table during times of low wind production. This requires no new technology. This makes more sense than batteries.
Reply | Report Abuse | Link to thisBatteries are expensive and inefficient. One of the limiting factors on production of hybrid cars is the availability and cost of batteries. If we start using batteries to store wind generated electricity it will impact the cost of batteries for cars etc.. Not to mention the fact that the battery plant that produces batteries for the Prius has caused a local environmental disaster with its waist.
HGTX33
Reply | Report Abuse | Link to thisI agree with you that pumped storage hydro facilities should be utilized to store the intermittent power from wind and solar. In fact, pumped storage hydroelectric facilities are the most efficient energy storage system available. The round trip efficiency is 72% (85% for generating and 85% for pumping) compared to less than 55% for compressed air energy storage. In addition, there are over 20 large (greater than 1000 MW) pumped storage facilities functioning in the U.S. at present so it is a tried and proven energy storage system. And, I'd like to emphasize once again, that it is a renewable energy storage system with "zero" emissions.
Vanadium is expensive and not plentiful. Sodium and sulfur are extremely plentiful and cheap. The only thing that makes sodium-sulfur expensive now is that they are not in mass production. But the degree to which vanadium-redox batteries can come down in price is limited by material costs.
Reply | Report Abuse | Link to thisVanadium-redox and sodium-sulfur can both achieve cycle efficiencies in excess of 85% energy return.
Sodium-sulfur batteries can handle between 2500-4500 charge-discharge cycles, where vanadium-redox batteries have been cycled more than 13,000 times without showing signs of deterioration.
Sodium-sulfur has to be heated to around 325C to operate however, the normal heat generated during charge and discharge is sufficient to maintain this temperature.
Since vanadium-redox uses a liquid for it's anode/cathode, the liquid electrodes can be "charged" in a different battery than it is discharged in.
In short, I think the sodium-sulfur battery is being considered in large part because it has the potential of being much more economical than vanadium-redox if mass produced.
Yes, the VRB are a mysteri. The values given by the company are revised all the time and you get a rather snotty answer when addressing them. Something strange here. Not so many large users in operation to my findings.
Reply | Report Abuse | Link to this