It makes me think of the Acquion project from Pittsburgh (http://aquionenergy.com/ http://aquionenergy.com/). That was an interesting attempt to commercialize e

It makes me think of the Acquion project from Pittsburgh (http://aquionenergy.com/ http://aquionenergy.com/). That was an interesting attempt to commercialize environmentally safe batteries intended for uses where low power density isn't a problem-- eg underground energy storage for windfarms or solar arrays. They went bankrupt a couple years ago, but the concept was really exciting. The immediate technical challenge with these kind of batteries at scale is the electronics to monitor and maintain the battery banks as well as deploying these things. It would take a truckload to set-up something usable for a house, I think.