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Storing megawatts: Liquid-metal batteries and electricity

The views expressed are those of the author and are not necessarily those of Scientific American.


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Making aluminum requires a lot of electricity. That’s because the metal bonds tightly to oxygen and it takes a lot of energy to break that bond. In essence, the process of making aluminum is a giant battery with the silvery metal being reduced to purity at the cathode while oxygen bonds with the carbon anode to make, you guessed it, CO2. It takes roughly 15 kilowatt-hours of electricity to make just one kilogram of aluminum via electrolysis.

But what if instead of making aluminum, one used the process to store electricity?

 

"What’s a big current sink? Aluminum smelters," explained Luis Ortiz, research director for materials scientist Donald Sadoway at the Massachusetts Institute of Technology (M.I.T.), at last week’s ARPA-E summit. "Maybe the aluminum industry is sitting on the answer [to large-scale electricity storage] all along."

Unfortunately, thanks to that CO2 gas floating away, this aluminum-making process turns out to be a very bad battery—it is simply not reversible. But David Bradwell, a graduate student in Sadoway’s lab, tweaked the process to involve liquid metals for the anode, cathode and even electrolyte and evolved a battery that has a high charge transfer, long life and costs "below $100 per kilowatt-hour," according to Ortiz. "It is as good or better than lithium ion in energy density but cheaper than lead acid."

Funding from ARPA-E will allow the researchers to take the liquid-metal battery from a "shot glass size cell to a pizza box cell," Ortiz said, and bring the concept closer to the goal of storing electricity at a cost of roughly $50 per kilowatt-hour. But as it stands "we get the energy back we put into it with reasonable efficiency."

And that could mean big things for storing electricity, as well as generating it from renewable but intermittent resources such as sunshine and wind. As Secretary of Energy Steven Chu told ScientificAmerican.com, "without energy storage, you can’t have a renewable electricity grid where perhaps 30, 40, 50 percent plus is coming from renewables."

Editor’s Note: David Biello is the host of a forthcoming series on PBS, tentatively titled "The Future of Electricity". The series will explore how transformation is coming to how we use and produce electricity, impacting the environment, national security and the economy. Detroit Public Television provided the video outtake embedded in this post.

 





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  1. 1. candide 5:54 pm 03/9/2010

    Storing electricity efficiently and reversibly will be a huge leap forward for many reasons Let’s hope this proves to be workable and economical.

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  2. 2. dwbd 10:36 pm 03/9/2010

    We already have lot’s of cheap Energy Storage it is called Fossil Fuels. The Big Question is why are we wasting that cheap Energy Storage to supply our steadystate energy demand, such as baseload power generation.

    Government Morons – use common sense, #1 focus: replace all baseload power generation with Nuclear & Hydro. Use fossil fuels only for Energy Storage or Chemical industry applications such as Transportation, Peaking Power plants, Winter peak Heating Loads.

    This latest craze to build NG baseload power generation is sheer, inexcusable stupidity.

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  3. 3. JamesDavis 7:45 am 03/10/2010

    SciAm has much better articles on liquid metal batteries that are better written and easier to understand. David Biello needs to go back to school and learn how to form an understandable English sentence that makes sense and not so badly fragmented. This is the worst written article I’ve seen from SciAm in several months.

    If Biello is going to host "The Future Of Electricity" like he wrote this article, no one will be able to understand what he is saying and the show will "suck" and will be taken off the air before anyone has a chance to make heads or tails of what’s going on or what he’s saying. Terriblely researched article.

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  4. 4. JamesDavis 8:05 am 03/10/2010

    dwbd: What do you do? work for or operate a fossil fuel plant of some kind? Or are you just another one of those brainless, mindless, spineless Republicans who thinks the environment is deplorable and should be dozed over on its side and raped of all its natural resources. You make about as much sense as this poorly written article does.

    That liquid metal battery could save America trillions of dollars in wasted energy and pollution clean up. Place one of these batteries at each persons home and they would never have to depend on anyone again to provide them electricity. Is that what you’re afraid is going to happen (dwbd), people are no longer going to be used and abused by the utility companys’ and these fossil fuel companys are going to be forced to clean up the destroyed and polluted land, water, and air their extraction efforts caused? Is that what you are so afraid of???

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  5. 5. tharriss 8:14 am 03/10/2010

    Hey dwbd, it is very short sited to think that focusing everything on Nuclear (which is enormously expensive too!) and Hydro is a good answer. Technology is in a huge boom period, with breakthroughs coming in many different fields all the time. We should leverage that development to find better cheaper answers than we have now… not hide our head in a hole in the sand and do more more more of the same.

    Sure, wind/solar or other alternatives aren’t there yet, but if we just steadily focus some research and initial development incentives in that direction, we’ll be much better off in the future.

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  6. 6. Soccerdad 9:29 am 03/10/2010

    dwbd

    Great points. I agree that making natural gas a larger part of electricity generation is foolhardy. We need to exploit nuclear for our electrical generation needs and reserve natural gas for better uses.

    Please ignore the rantings of jamesdavis. As far as I can tell, he has some sort of irrational fear of fossil fuels, and thinks that anyone who advocates for the responsible use of fossil fuels is somehow paid by an oil company or coal company.

    For all the complaining Mr. davis does about the article and some posts being poorly written, I’m not really sure he is setting a high standard himself. Consider the following quotes:

    "Or are you just another one of those brainless, mindless, spineless Republicans who thinks the environment is deplorable and should be dozed over on its side and raped of all its natural resources. "

    "Is that what you’re afraid is going to happen (dwbd), people are no longer going to be used and abused by the utility companys’ and these fossil fuel companys are going to be forced to clean up the destroyed and polluted land, water, and air their extraction efforts caused? Is that what you are so afraid of???"

    Link to this
  7. 7. bertwindon 3:58 pm 03/10/2010

    The Watt is a unit of rate of trasfer of energy. It equals a steady rate of work of one Joule of energy moved each second.
    To store a rate is a non-sense propositon, i.e. it has no meaning. Energy is moved at a rate of so many Watts. I is Energy that we waqnt to store. This is measured in Joules. One Joule of work is done, or energy transfered by something, if it pushes something-else with a force of one Newton, for a distance of one metre. These definitions might not be "American", but they are scientific.

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  8. 8. bertwindon 4:08 pm 03/10/2010

    Oh please let us have a "renewable electricity grid" ??! even if we have to suffer from "storage" !

    Link to this
  9. 9. bertwindon 4:20 pm 03/10/2010

    @tharris
    As you say nuclear is horrendously expensive. In my mind it is more than that, it will cost The Earth – or certainly the life on it. E.g. with only the mere coal for energy, the "noveau rich" of China can now afford a car and a rifle to go earn themselves a little extra – to pay the installments – by killing the remaining Rhinos, Tigers – whatever, they can hardly tell the difference.
    Solar heating is very effective, and not at all high tech., and as you say there are breakthroughs "all the time". There is one such in the field of Wind-energy. The current (80m high) "technology" returns, annually, around 1/40th of the percentage of its cost that is actually obtainable from a sensible design of Turbine-Alternator. There are 4 major reasons for this.
    As for "liquid metal Baterries" – well, we all so enjoy this little kind of joke.

    Link to this
  10. 10. bertwindon 4:33 pm 03/10/2010

    Well, man. If you got all this cheap energy storage why are you wasting time telling us about it ? Get out there and sell it !

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  11. 11. profgroove 9:54 pm 03/11/2010

    Are sodium-aluminum alloy batteries being investigated? Na + Al + H2O = H2 + sodium aluminate (innocuous). Can we get electricity directly instead of H2 and is the reaction easily reversible (i.e. electrically decompose the sodium aluminate)?

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  12. 12. Wayne Williamson 12:32 pm 03/13/2010

    i don’t understand the "bus" size storage for 1mw…if the density is similar to lithium batteries it should be something like (250w per liter = 250kw per cubic meter) or around 4 cubic meters for a megawatt…or roughly 6ftx6ftx3ft…maybe double that for the inverters, etc…

    i do like the idea of having high density batteries made from common materials…

    i would like one of these hooked to my house…but not for 50k…try 10k is more reasonable…

    good luck and spend the money well…

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  13. 13. elderlybloke 11:21 pm 03/13/2010

    bertwindon- I draw your attention to France (clue-it is in Europe), where they have been successfully using Nuclear Energy to produce electricity for decades.
    About 80% actually, but for some reason the ignorant Americans have no knowledge of this.

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  14. 14. Michael Hanlon 11:56 pm 03/14/2010

    What happened to cold fusion? No batteries were going to be necessary at all because we were to produce as needed at site by combning hydrogen atoms into helium (oops bad waste product) So that didn’t pan out and we now find ourselves fifty years behind schedule on energy storage technologies.

    Both sides, stop fighting and agree that having efficient energy storage is a good thing!

    Link to this
  15. 15. robertjackson789 8:28 am 10/29/2010

    Oh please let us have a "renewable electricity grid" ??! even if we have to suffer from "storage" !

    <a href="http://www.crewsavings.com">Best Savings Accounts</a>

    Link to this
  16. 16. robertjackson789 8:29 am 10/29/2010

    For all the complaining Mr. davis does about the article and some posts being poorly written, I’m not really sure he is setting a high standard himself.

    <a href="http://www.crewsavings.com">Best Savings Accounts</a>

    Link to this
  17. 17. robertjackson789 8:31 am 10/29/2010

    Oh please let us have a "renewable electricity grid" ??! even if we have to suffer from "storage" !

    [url="http://www.crewsavings.com"Best Savings Accounts[/url]

    Link to this
  18. 18. jasondonald 11:08 am 10/29/2010

    Oh please let us have a "renewable electricity grid" ??! even if we have to suffer from "storage" !

    ================
    jasondonald
    <a href="http://www.crewsavings.com&quot; rel="nofollow">best savings accounts</a>

    Link to this
  19. 19. DavidHuieGreen 1:19 pm 04/23/2011

    REGARDING:”The Watt is a unit of rate of transfer of energy. It equals a steady rate of work of one Joule of energy moved each second.- – To store a rate is a non-sense proposition, i.e. it has no meaning”

    While this is true, I’m not sure how it applies here unless it is a complaint about statements like:”storing electricity at a cost of roughly $50 per kilowatt-hour”.

    I could see the complaint about saying electricity is stored rather than saying energy is stored, but hope the complainer understands a kilowatt-hour is equivalent to a kilowatt of power for one hour of operation or a thousand Joules per second times 3600 seconds or 3.6 million joules of energy. That’s what one kilowatt-hour is.

    (If confused, please remember a man-hour is one man or worker working for one hour. Some jobs are figured in man-hours because they give an idea of the time and cost of the project.)

    Anyhoo, a kilowatt-hour is also the amount of energy involved in 3.6 megawatts for one second or one watt for 3.6 million seconds. It’s just a convenient way of expressing energy since appliances are given in watt and kilowatt power demand.

    Link to this

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