The Forever Battery
Imergy Power Systems’ headquarters in an office park in one of Silicon Valley’s less glamorous precincts is the type of place where the future used to be invented. There are no Beats headphones-wearing 20-somethings on scooters. No foosball tables, rooftop beer garden or ironically named conference rooms. No birdhouses. Just a sea of drab, blue-gray cubicles. The median employee age appears to be around that of the typical software engineer who files an age-discrimination lawsuit. There are scientists wearing white lab coats. Some have white hair. The chief executive is 61 – that’s 120 in Silicon Valley years.
Needless to say, Imergy is not developing the next $19 billion app that Facebook will acquire, but the startup could end up powering Facebook.
"Basically, our battery lasts forever."
Imergy has spent years perfecting an energy storage device that, if it lives up to its billing, will help accelerate the big green future by allowing companies and homeowners to pull the plug on their local utility by banking electricity from solar arrays and wind farms for use when the sun is not shining or the wind is not blowing. A 250-kilowatt battery system installed in a 40-foot container, for instance, could store solar energy from the rooftop arrays of a 40-home neighborhood for later use.
This magic box is called a Vanadium redox flow battery. The heart of a flow battery are two electrolyte solutions – one positive, one negative – contained in separate tanks. When the solutions are pumped through a power cell containing a membrane, a chemical reaction takes place that generates electricity. When the process is reversed, the electrolyte stores energy.
http://www.theatlantic.com/technology/archive/2014/04/the-forever-battery/361167/
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= new reply since forum marked as read
Storing energy is a real bitch. One has to fight thermodynamics, physics, chemistry, and it all has to have large storage (apparently good here), recharge cycles (also apparently good), cheap to build (uh oh), small (double uh oh), and a myriad of other things.
Battery tech advances are going to be incremental for the foreseen future. At least until we discover dilithium crystals and anti-matter energy. (But Captain! The dilithium crystals canno take it much longer!)
The best solution. Put billions into research on all of the above.
The science was worked out decades ago -- take second semester General Chemistry and you'll know more about this device than what you'll find in the science "journalism" stories on this topic. There appears to be no *really* new technology involved (membrane cells have been around for a while), though you won't find the details in this drive-by reportage. It *is* an incremental improvement over other storage batteries, such as lead-acid, but revolutionary -- no, not without a fairly generous definition of that term. It is a business opportunity, not a world-changer.
Because it uses solutions rather than pure liquids or solids, it is much too bulky and heavy for portable uses. Also, vanadium is much higher atomic weight than lithium, so that adds to the weight. The "non-toxic electrolyte" is apparently sulfuric acid 
-- which doesn't stop proponents from dismissing lithium (once an ingredient in 7-Up) in competing technologies as "toxic". Oh, and both redox reactions are one-electron processes -- a two-electron process would halve the amount of solute required, all other things being equal (an important qualifier).
"two solutions, one positive, one negative ..." Barf. OK, not everyone stuck through the second semester, but that's still horribly inaccurate descriptive writing. In fact, one side of the cell uses the V(V)/V(IV) couple, the other V(III)/V(II). The advantage of this setup is that both reactants and products in both sides of the cell are in solution -- no solids, which leads to complications which limit the lifetime of lead-acid, lithium, NiCd, etc. cells. If the two solutions don't mix, there's no need to use the same element on both sides -- I don't know if there's a compelling reason for it in this device, but there's a good chance these two couples aren't the only ones that work well. After all, the Periodic Table has a little something in it for everybody. 
It's worth noting that these cells have been in commercial use since 2000, and they haven't shaken the ground under anyone's feet, as far as I can tell.
I was educated in physics, but have some chemistry, too, most of which I have forgotten. 
Your post brought back some memories.
A great response, BTW.
Best regards.
Keeping it below 131 will be no problem!
