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Clean Power "Professor Donald Sadoway and Materials Processing Center Research Affiliate David Bradwell observe one of their small test batteries in the lab. The battery itself is inside the heavily insulated metal cylinder at center, which heats it to 700 degrees Celsius." (Photo: Patrick Gillooly; Source: MIT)

Published on February 20th, 2012 | by Nicholas Brown

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MIT: Liquid Batteries Have Huge Potential

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February 20th, 2012 by  

“Professor Donald Sadoway and Materials Processing Center Research Affiliate David Bradwell observe one of their small test batteries in the lab. The battery itself is inside the heavily insulated metal cylinder at center, which heats it to 700 degrees Celsius.” (Photo: Patrick Gillooly; Source: MIT)

According to new research conducted by the Massachusetts Institute of Technology and published in the Journal of the American Chemical Society, renewable sources of energy such as the sun and wind could become economically competitive with traditional sources of energy via the use of “liquid batteries.”

While MIT has made many announcements in the past of inventions of that could potentially be cheaper than traditional energy storage systems such as the lithium-ion or lead-acid batteries in use today, this is perhaps the most promising I have seen.

Wind & Solar Intermittency, & Solutions Up Until Now

The sun does not always shine, the wind does not always blow, wind speeds fluctuate, and the amount of sunlight we receive varies due to clouds. Thus, the power we can generate from wind and solar energy fluctuates.

According to the United States Department of Energy 2011 Annual Energy Outlook, the average cost of wind power in the U.S is only 9.7 cents per kWh (kilowatt-hour) of electricity. Wind power’s problem is no longer the cost to generate it. It is now mainly intermittency.

Fluctuations in the amount of power generated by a wind farm can be compensated for by adjusting other hydroelectric, nuclear, or fossil-fueled natural gas or coal power plants. If a wind farm generates more than necessary, other power plants can be turned down to compensate for that, and back up again when there is less than enough wind power available. The ability of nuclear and coal power plants to adjust is very limited, however, because they take long to make major adjustments in power production.

Energy storage, on the other hand, enables wind farms to independently supply power without the help of other power plants. Battery banks are a form of energy storage system that can achieve this, but they have traditionally been too expensive to compete.


MIT’s Liquid Batteries

According to MIT, liquid batteries are inexpensive and last longer than traditional batteries. The three materials contained in the liquid batteries each settle in separate layers due to the difference in their densities, which, in this case, is a good thing. They need to be separate.

This project was conducted with the importance of material availability and abundance in mind. “We explored many chemistries,” Donald Sadoway, the John F. Elliott Professor of Materials Chemistry at MIT and the senior author of the new paper, says. All three layers of the materials used are abundant and inexpensive.

The combination published in the new paper: The negative electrode (anode) is in the top layer and is made of magnesium; the middle layer, the electrolyte, consists of a salt mixture containing magnesium chloride; and the bottom layer, which is the positive electrode (cathode), is made of antimony.

This battery operates at a temperature of 700 °C, which is 1,292 °F.

Discharging: The battery generates an electric current as each magnesium atom (this is in the negative electrode) loses two electrons, then becoming magnesium ions which travel to the other antimony electrode. The magnesium ions then reacquire two more electrons and become magnesium again because of this. This causes an alloy to form with the antimony.

Charging: When the battery is supplied with an electric current, this process is reversed and the electrons are driven out of the antimony electrode, and back to the magnesium electrode.

As I often emphasize: batteries do not actually store electricity, they generate it. When you charge a battery,  you supply it with an electric current that drives a chemical reaction of which the one mentioned above is an example.  You reverse that process to make the battery generate electricity.

This looks like an exciting new development. What do you think?

Source: MIT News Office

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About the Author

writes on CleanTechnica, Gas2, Kleef&Co, and Green Building Elements. He has a keen interest in physics-intensive topics such as electricity generation, refrigeration and air conditioning technology, energy storage, and geography. His website is: Kompulsa.com.



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  • Drocketman2000

    This will only store DC electricity, AC is used in the poly phase electrical system. The relatively high temps needed to make it work (1,292 degrees F- 700 degrees C) is a MAJOR concern where there is a high temp diff in the environment, making heat insulation an additional cost factor. Unless it was buried underground in a concrete bunker to minimize heat loss, but then the bunker won’t be cheap at all.
    Thyristors big enough to switch the 500KV DC power from the Pacific Intertie into AC like at the SCE inverter station in Sylmar, Calif. would be another additional cost to factor in. You should see the SIZE of those things!! HUUUUGE!!
    In short, thumbs down on this “idea”, I just don’t see any real world advantages to it.

    Drocketman

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  • Bob_Wallace

    Here’s what seems to be serious competition….

    Aquion batteries – sodium ion (“salt water”) batteries.

    Inexpensive materials. Activated carbon anode and a sodium- and manganese-based cathode.

    Operate at room temperature. No self discharge or problems in high heat conditions.

    Can be 100% discharged without damage.

    High tolerance to battery mismatch.

    100% recyclable.

    Third party testing >5,000 cycles rapid charges with no degrading. Company expects 20,000 cycles when fully developed.

    Tested for two calendar years so far with no loss of performance.

    Expected price around $300/kW.

    @5,000 cycles = $0.06/kWh, @10,000 cycles = $0.03/kWh, @20,000 cycles = $0.015/kWh.

    (Back of envelop calculations)
    $0.05/kWh Wind + $0.03/kWh Storage + Overhead + 15% Loss (85% Efficient) =~ $0.10/kWh Stored Wind.

    Solar is expected to fall to close to $0.06/kWh.

    That makes a combination of wind, solar and stored wind/solar cheaper than new nuclear or new coal. (Or old coal if you add in externalities.) Certainly cheaper than natural gas peaking plants.

    Lighter weight than lead acid batteries – cheaper shipping.

    Going into production. Currently setting up factory in Pennsylvania. Expect to be manufacturing in 2013.

    http://www.aquionenergy.com/applications/

    Now, if the MIT solution is even better, that’s a good thing….

  • Braver

    I agree with the previous comment, this article doesn’t have any numbers. How could the author conclude that is an exciting new development without comparing with existing batteries? Does it store more energy per unit weight? Is it cheaper per unit of stored energy?

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  • tsvieps

    ” All three layers of the materials used are abundant and inexpensive.”

    Fine, but just talk, no numbers…no indication of cost per KWH in a commercial application or time range to get there.

    • Ross

      During his TED talk http://www.youtube.com/watch?v=Sddb0Khx0yA he implies that the costs of production of the batteries will be low.

      The battery uses molten Magnesium ($1.5/LB) and Antimony ($6/LB) separated by a salt electrolyte.

  • Stan

    It’s formulaic….watts to BTUs…..measured in cubic ft of the liquid.

  • Peterb01

    how much E is expended to maintain the battery at 1300F?

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