
MIT’s Liquid Metal Stores Solar Power Until After Sundown - adventured
http://www.bloomberg.com/news/2014-03-06/mit-s-liquid-metal-stores-solar-power-until-after-sundown.html
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jessaustin
TFA is pretty thin on info. The "$500/kWh" goal seems to come from Musk's
battery marketing rather than something inherent to this technology. And the
technology itself isn't even hinted at. The description of "earlier versions"
seems to imply a chemical reaction like regular batteries. However,
speculating based on "liquid metal", maybe they've identified a metal with a
melting point around ambient temp (or ambient temp of a sufficiently insulated
vessel)? With high enough specific heat (typical for metals anyway), it could
soak up energy by melting, and release it by freezing.

~~~
throwaway_yy2Di
Very thin:

    
    
        "Sadoway, who is also the John F. Elliott professor 
        of materials chemistry at Massachusetts Institute of 
        Technology, wouldn’t say what goes into liquid-metal 
        batteries."

Here's a description from an earlier article -- same idea with different
materials:

    
    
        "After hitting upon the idea of the liquid-metal 
        battery, ­Sadoway searched for the perfect electrodes: 
        he ended up choosing magnesium and antimony because 
        they are cheap and separate naturally when in liquid 
        form, the lighter magnesium rising to the top. A 
        liquid-salt electrolyte rests between the magnesium 
        and antimony electrodes, creating a cell with three 
        layers."

[http://www.technologyreview.com/featuredstory/511081/am](http://www.technologyreview.com/featuredstory/511081/am)

So it's a chemical battery where the electrodes are liquids. (FWIW: Magnesium
melts at 650 °C).

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tjmc
I hope this works out, but it bothers me when inventors use slick lines like
"If you want something to be dirt cheap it needs to be made of dirt." It
suggests to me they've been spending more time polishing their TED talks and
investor presentations than in the lab.

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andrewflnr
Hm, not really. I see what you mean, but that's the kind of thing you start
thinking about in the shower or when you're stuck on the real problem and need
a break. Even before that, it's been circulating in your subconscious and may
just pop out whole. It's not evidence either way of their technical ability.

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tlb
They claim under $500/kWh, but classic lead-acid costs only $170/kWh.

Source: [http://www.allaboutbatteries.com/Battery-
Energy.html](http://www.allaboutbatteries.com/Battery-Energy.html)

~~~
sp332
I would guess those aren't deep-cycle batteries, and can be damaged by
draining them even a few times.

~~~
hengheng
Nothing a good controller couldn't solve.

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tedsanders
Are you being serious here? (I cannot tell.) A controller cannot prevent
structural damage to the electrodes. I once did research on using lead acid
for grid applications. Shallow cycling doesn't save you much. You may double
your cycles but if you get just half the energy from each cycle, then the
battery's lifetime energy return is not all that dramatically improved.

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JumpCrisscross
In 2012, McKinsey & Co. reported on hybrid-electric, plug-in hybrid, and
battery-electric vehicle (EV) competitiveness [1]. The focus was the impact of
rising petrol and battery prices (measured in dollars per kilowatt hour).

U.S. gas prices are, as of 3 March 2014, around $3.48 per gallon [2]. This
means EVs need battery prices south of $300/kWh. Even hybrid-electrics want no
more than $400/kWh. The $500/kWh mentioned in the article, around Tesla
Motors's costs, is not game-changing for automobiles.

[1]
[http://www.mckinsey.com/insights/energy_resources_materials/...](http://www.mckinsey.com/insights/energy_resources_materials/battery_technology_charges_ahead)

[2]
[http://www.eia.gov/petroleum/gasdiesel/](http://www.eia.gov/petroleum/gasdiesel/)

~~~
marvin
Just as a side note, Tesla Motors's battery costs are probably lower than
this. (In the region of $200-$400/kWh)

[http://www.teslamotorsclub.com/showthread.php/17590-Model-S-...](http://www.teslamotorsclub.com/showthread.php/17590-Model-
S-Battery-Pack-Cost-Per-kWh-Estimate)

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ColdHawaiian
It's cool that this new storage system is 1/3 the cost of current battery
technology, but I wonder what the environmental impact of "liquid metal"
batteries would be. The article says one of their prototypes used antimony,
which is toxic, with effects "that are similar to arsenic poisoning"[1].

[1]:
[http://en.wikipedia.org/wiki/Antimony#Precautions](http://en.wikipedia.org/wiki/Antimony#Precautions)

Lithium-ion batteries, at least, "contain no toxic metals"[2].

[2]: [http://en.wikipedia.org/wiki/Lithium-
ion_battery#Environment...](http://en.wikipedia.org/wiki/Lithium-
ion_battery#Environmental_concerns_and_recycling)

~~~
troymc
Lithium and lithium compounds can be toxic:

[https://en.wikipedia.org/wiki/Lithium#Precautions](https://en.wikipedia.org/wiki/Lithium#Precautions)

The batteries envisioned by Ambri would be enormous, shipping-container-sized
things sitting (stationary) in the same place (e.g. electrical substations)
for decades. If one cracked open, it would be a bad day at the plant, but
nothing like a nuclear reactor meltdown. It could probably be back to normal
in days or weeks.

The fact that the Ambri batteries are made using abundant materials means that
those very materials are already present, in vast quantities, in the
environment.

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csense
How much energy has to be used to keep the metal liquid? Can you switch the
heating system off and let everything solidify without damage if you don't
plan on charging or discharging in the near future? (Likewise with unexpected
power outages.)

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DennisP
> Earlier versions used molten magnesium and antimony

I once calculated about how much magnesium and antimony would be needed to run
the world on solar, using these batteries for storage. Based on the numbers I
found in articles like this, and a little wikipedia, it came out to a thousand
times our annual production of one of these metals, and ten thousand times our
annual production of the other.

For a similar calculation using lead-acid batteries, see this post at Tom
Murphy's Do the Math blog: [https://physics.ucsd.edu/do-the-
math/2011/08/nation-sized-ba...](https://physics.ucsd.edu/do-the-
math/2011/08/nation-sized-battery/)

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jccooper
Seems like this is a similar setup but different chemistry along the lines
sodium-sulfur batteries (which are a molten salt). I had thought sodium-sulfur
batteries were already at or better than $500/kWh; pretty sure new generations
will be. There's already several hundred MW of NaS installed already.

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joshlegs
I'm pretty sure one of my high school friends is an engineer at that compnay.
He lives in boston and told me he's working on batteries for a company backed
by Bill Gates. That's pretty awesome

