Eos Energy Storage | Technology and Products They claim $160/kWh, 10k cycles (30 years). Zinc Air batteries (don't metal air Li-Ion fall apart?). They seem ready for market quite soon. I'm looking for a catch.

Power density and efficiency suck? 75% efficiency is terrible. No mention of the actual power density, which has also been a fundamental problem of air batteries. Also note that they don't actually give the energy density, they just say "4 33ft NEMA containers". Anyone care to do the math on 1MWh in a 33ft NEMA container? And dod is? "Today's batteries, such as lead-acid and lithium ion rely on rare earth metals..." yer what? Add it to a growing list of battery ... er ... bluster (and I include Tesla in that).

Ok, Could there be a simple way to adjust the price to better compare to Tesla's $250/kWh, 90-something% efficiency? 250/.92 = 270, 160/.75 = 213. I'd guess it's more complicated than that, but is there some simple way to show an 'effective' price? - - - Updated - - - http://www.eosenergystorage.com/wp-content/uploads/2013/04/Eos-Public-Presentation-2013-02-11.pdf Price per Power (edit) is $1000/kW. For Tesla from my understanding it is $500/kW. So there is a difference. Not sure what is the significance.

OK, so poor power density as expected. So, value comes with storage capacity. But then that 75% efficiency is a downer, because that's adding 1/3 to the cost of the stored electricity, while a 92% efficiency adds 2/23.