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Published on November 18th, 2008 | by Alex Felsinger

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New Cost-Effective Battery Tested to Store Wind-Power




For the first time in America, a company has developed an efficient battery solution to storing wind power, a clear answer to critics who claim turbines are unreliable.

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Xcel Energy‘s “Wind-to-Battery” project is currently being tested on a Minnesota wind farm. The company believes that the 80-ton battery will power 500 homes for 7 hours when fully charged. The battery’s 20 50-kilowatt modules together are roughly the size of two semi- trailers and can store 7.2 megawatt-hours of electricity.

“Energy storage is key to expanding the use of renewable energy,” said Dick Kelly, Xcel Energy Chairman, President and CEO. “This technology has the potential to reduce the impact caused by the variability and limited predictability of wind energy generation. As the nation’s leader in distributing wind energy, this will be very important to both us and our customers.”

The sodium-sulfur battery technology has already been used in a variety of forms in the United States, but Xcel says their pilot program is the first time any practical and efficient battery storage technology has been used on a wind farm.

Photo Credit: Ryan McD on Flickr under Creative Commons license.

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About the Author

is primarily concerned with animal welfare, wildlife conservation, and environmental justice. As a freelance writer in San Francisco, he leads a deliberately simplistic and thrifty lifestyle, yet still can’t help gawking at the newest green gadgets and zero-emission concept cars.



  • Chris S.

    I wonder about this whole claim of cost-effectiveness.How much energy cost goes into maintaining molten sulfur at such a high temperature? Seems like batteries that operate at normal environmental temperatures would be more efficient.

  • Chris S.

    I wonder about this whole claim of cost-effectiveness.How much energy cost goes into maintaining molten sulfur at such a high temperature? Seems like batteries that operate at normal environmental temperatures would be more efficient.

  • WlkBht

    This is similar to charging a battery overnight so you can use it during the day, you are effectively deferring the load (of course there are many other considerations, and I’ll agree, something about it just seems wrong…)

  • WlkBht

    This is similar to charging a battery overnight so you can use it during the day, you are effectively deferring the load (of course there are many other considerations, and I’ll agree, something about it just seems wrong…)

  • WlkBht

    sane : “I assume you are not suggesting that someone would let water flow through a dam to generate electricity so as to then pump water up hill…” This is exactly what Pump Storage is; the water is pumped at a time when generation is greater than demand (say, at night) and released at a time when demand exceeds the normal generation, such as morning and evening peaks.

  • WlkBht

    sane : “I assume you are not suggesting that someone would let water flow through a dam to generate electricity so as to then pump water up hill…” This is exactly what Pump Storage is; the water is pumped at a time when generation is greater than demand (say, at night) and released at a time when demand exceeds the normal generation, such as morning and evening peaks.

  • http://globalpatriot.com Global Patriot

    As mentioned above, storage on the grid is one of the key issues with aggressively moving ahead on the alternative energy front. And while we should continue advancing battery technology for many situations, I would like to see other alternatives investigated that don’t carry the same issues as battery maintenance and recycling.

  • http://globalpatriot.com Global Patriot

    As mentioned above, storage on the grid is one of the key issues with aggressively moving ahead on the alternative energy front. And while we should continue advancing battery technology for many situations, I would like to see other alternatives investigated that don’t carry the same issues as battery maintenance and recycling.

  • hexyl

    Why is energy storage so important?

    For the power industry integrating renewables is not so simple. The load (power that the customers use) varies throught the day with peaks and lows but it can be predicted and accounted for. The power companies use the preditction to set their generation schedules and make minute adjustments. When you have a renewable like wind/solar/wave which can suddenly stop or start producing power the Power Plants generating units must now make large adjustments because the load at that time will still remain the same. This can work both ways too. At a load peak the renewable drops to 0 and the PP must ramp up and generate more. Lets also postulate when the load is at the daily minimum. The PP will also be at a minimum. What if the renewables are at 0 MW and suddenly the renewables start pumping MW into the grid? What do the PP do? There is more generation than load, now they must decrease output. However the PP units are aready at thier lowest output so one of two things will happen. The PP will either trip offline or the operators will pull equipment offline in a hurry to avoid a unit trip. Neither is good for PPs which are supposed to constantly operate. Having a combination of steady renewable power output and a “smart” electric grid will prevent PP from dancing around. Utilities will be much more open to having renewables tied into the grid.

    Why can’t PP react quickly to grid changes? The most efficient type of PP we have are based on the steam cycle. Fuel is burnt in a boiler to heat up water to steam which is shot through a turnbine conencted to a generator. Whatever is left over is condensed back to water and then goes back to the boiler to be heated again. Control of the boiler is very slow compared to the type of MW fluxuations that could come from a renewable source.

  • hexyl

    Why is energy storage so important?

    For the power industry integrating renewables is not so simple. The load (power that the customers use) varies throught the day with peaks and lows but it can be predicted and accounted for. The power companies use the preditction to set their generation schedules and make minute adjustments. When you have a renewable like wind/solar/wave which can suddenly stop or start producing power the Power Plants generating units must now make large adjustments because the load at that time will still remain the same. This can work both ways too. At a load peak the renewable drops to 0 and the PP must ramp up and generate more. Lets also postulate when the load is at the daily minimum. The PP will also be at a minimum. What if the renewables are at 0 MW and suddenly the renewables start pumping MW into the grid? What do the PP do? There is more generation than load, now they must decrease output. However the PP units are aready at thier lowest output so one of two things will happen. The PP will either trip offline or the operators will pull equipment offline in a hurry to avoid a unit trip. Neither is good for PPs which are supposed to constantly operate. Having a combination of steady renewable power output and a “smart” electric grid will prevent PP from dancing around. Utilities will be much more open to having renewables tied into the grid.

    Why can’t PP react quickly to grid changes? The most efficient type of PP we have are based on the steam cycle. Fuel is burnt in a boiler to heat up water to steam which is shot through a turnbine conencted to a generator. Whatever is left over is condensed back to water and then goes back to the boiler to be heated again. Control of the boiler is very slow compared to the type of MW fluxuations that could come from a renewable source.

  • Sane

    biganon…”Water is pumped up from large reservoirs at night using wind or hydro “…Pumped storage is indeed an interesting option. However, in the above statement I assume you are not suggesting that someone would let water flow through a dam to generate electricity so as to then pump water up hill…Rather I’m guessing what you’re talking about is that that hydro power is similar to pumped storage and can be used in a similar way to mitigate variable wind rates (with hydo power, rather than wind doing the pumping, in hydro power the sun is effectively “pumping” the water up hill by evaporating it) but either way you can control when and where you release it once it is captured.

  • Sane

    biganon…”Water is pumped up from large reservoirs at night using wind or hydro “…Pumped storage is indeed an interesting option. However, in the above statement I assume you are not suggesting that someone would let water flow through a dam to generate electricity so as to then pump water up hill…Rather I’m guessing what you’re talking about is that that hydro power is similar to pumped storage and can be used in a similar way to mitigate variable wind rates (with hydo power, rather than wind doing the pumping, in hydro power the sun is effectively “pumping” the water up hill by evaporating it) but either way you can control when and where you release it once it is captured.

  • Ben

    How many recharges are the batteries good for until they die?

  • Ben

    How many recharges are the batteries good for until they die?

  • http://apps.jooopa.net denwer

    I also wonder what will happen to the “peak” electricity usage during the day, once everyone is possibly plugging in their cars at night. Does anyone know anything about that?

  • http://apps.jooopa.net denwer

    I also wonder what will happen to the “peak” electricity usage during the day, once everyone is possibly plugging in their cars at night. Does anyone know anything about that?

  • Jeff Shragge

    I’m glad to see that progress is being made on large-scale energy storage. I agree with the comments above saying that it is effectively a requirement before wind power really takes off and becomes a significant part of the global energy portfolio.

    However, I’m a little concerned about the 80 ton weight remark – especially the energy required to complete the mining, processing, engineering and component fabrication. It would be interesting to know what the overhead costs of the battery currently are (in terms of the equivalent # of years of an operating wind unit).

    Hopefully, much like when computers were giant multi-ton beasts 50 years ago, these batteries will go through a rapid miniaturization process!

  • Jeff Shragge

    I’m glad to see that progress is being made on large-scale energy storage. I agree with the comments above saying that it is effectively a requirement before wind power really takes off and becomes a significant part of the global energy portfolio.

    However, I’m a little concerned about the 80 ton weight remark – especially the energy required to complete the mining, processing, engineering and component fabrication. It would be interesting to know what the overhead costs of the battery currently are (in terms of the equivalent # of years of an operating wind unit).

    Hopefully, much like when computers were giant multi-ton beasts 50 years ago, these batteries will go through a rapid miniaturization process!

  • http://www.utility-savings.com Charles R. Toca

    This is molton sodium sulfur, the NAS battery developed by NGK of Japan – runs over 300 Centigrade. 1 MW at 7.2 hours of storage is their standard configuration. Since NGK sells so many products to utilities already – ceramic insulators for electric distribution lines for example – many utilities seem to be focusing on them and ignoring other technologies like vanadium flow batteries. Too bad we seem to be sole sourcing a Japanese technology instead of supporting systems made in North America.

    The author was a bit duped by Xcel, the vanadium battery has been used for wind farms in Japan and Tazmania for several years – including a 6 MW system on Hokkaido.

  • http://www.utility-savings.com Charles R. Toca

    This is molton sodium sulfur, the NAS battery developed by NGK of Japan – runs over 300 Centigrade. 1 MW at 7.2 hours of storage is their standard configuration. Since NGK sells so many products to utilities already – ceramic insulators for electric distribution lines for example – many utilities seem to be focusing on them and ignoring other technologies like vanadium flow batteries. Too bad we seem to be sole sourcing a Japanese technology instead of supporting systems made in North America.

    The author was a bit duped by Xcel, the vanadium battery has been used for wind farms in Japan and Tazmania for several years – including a 6 MW system on Hokkaido.

  • http://www.theenergyroadmap.com Garry G

    I think this the missing ingredient in our conversation over growing renewable portfolios…

    While many eco activists channel their emotions at Big Oil (as the great conspiracy) it is actually ‘Big Grid’ which holds the key to success for solar and wind.

    Without energy storage systems, they are not likely to evolve…

    Thanks for the post!!

    Garry Golden

    Editor

    The Energy Roadmap.com

    http://www.theenergyroadmap.com

  • http://www.theenergyroadmap.com Garry G

    I think this the missing ingredient in our conversation over growing renewable portfolios…

    While many eco activists channel their emotions at Big Oil (as the great conspiracy) it is actually ‘Big Grid’ which holds the key to success for solar and wind.

    Without energy storage systems, they are not likely to evolve…

    Thanks for the post!!

    Garry Golden

    Editor

    The Energy Roadmap.com

    http://www.theenergyroadmap.com

  • http://www.globalwarmingisreal.com/blog Tom Schueneman

    What exactly is the technology of this battery? I did a piece last week on Vanadium battery technology for renewable storage applications – is this what we’re talking about here?

    http://www.triplepundit.com/pages/vanadium-battery-technology-makes-commer.php

  • http://www.globalwarmingisreal.com/blog Tom Schueneman

    What exactly is the technology of this battery? I did a piece last week on Vanadium battery technology for renewable storage applications – is this what we’re talking about here?

    http://www.triplepundit.com/pages/vanadium-battery-technology-makes-commer.php

  • JG

    It seems as though the “peak” electricity during the day would not change if everyone would plug their car into an outlet with a simple timer that would start charging at bed time. This would just make the valleys of usage less severe and allow the utilites to better utilize their generating assets by running them more constantly (as opposed to shutting some generators down every night).

  • JG

    It seems as though the “peak” electricity during the day would not change if everyone would plug their car into an outlet with a simple timer that would start charging at bed time. This would just make the valleys of usage less severe and allow the utilites to better utilize their generating assets by running them more constantly (as opposed to shutting some generators down every night).

  • biganon

    I also wonder what will happen to the “peak” electricity usage during the day, once everyone is possibly plugging in their cars at night. Does anyone know anything about that?

  • biganon

    I also wonder what will happen to the “peak” electricity usage during the day, once everyone is possibly plugging in their cars at night. Does anyone know anything about that?

  • biganon

    Pump storage is also a method of alternative energy storage. Water is pumped up from large reservoirs at night using wind or hydro and released during peak electricity usage to turn turbines on the way back down. New systems are drilling large caverns into bedrock, rather than using natural ponds/lakes with unequal heights.

    I’m not sure which is more efficient, nor do I know what the environmental impacts of pump storage would be on a natural ecosystem. Is anyone able to compare and contrast?

  • biganon

    Pump storage is also a method of alternative energy storage. Water is pumped up from large reservoirs at night using wind or hydro and released during peak electricity usage to turn turbines on the way back down. New systems are drilling large caverns into bedrock, rather than using natural ponds/lakes with unequal heights.

    I’m not sure which is more efficient, nor do I know what the environmental impacts of pump storage would be on a natural ecosystem. Is anyone able to compare and contrast?

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