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Zinc-air battery company Eos Energy Storage raises $15M

Eos Energy Storage, a developer of zinc-air grid-scale battery technology, completed its $15-million Series B financing round with participation from a syndicate of 21 strategic and financial investors.

Eos has developed Znyth, a zinc hybrid cathode battery technology. According to Eos, Znyth has demonstrated more than 5,000 cycles to date with no physical degradation. The company saus it has overcome historical limitations of zinc-air batteries, with its innovations improving round-trip efficiency, energy density, cycle life, and run time.

Eos’s Aurora grid-scale energy storage product has been specifically engineered to help utilities operate more efficiently and create savings for consumers by time-shifting peak energy demand while providing greater resilience to the electricity grid.

The Aurora system is delivered in a standard 40’ container, and comes in 1 MWh and 6 MWh standard sizes, built, respectively, with 2 kWh and 12 kWh modules. Initial pricing is expected to be $160/kWh.

Eos will begin deploying the Aurora in 2014. The company is in advanced discussions with several states regarding the location of its pilot manufacturing facilities.

Eos is also developing the Vista zinc flow battery, targeted for electric vehicle as well as stationary applications. Based on the

Two high-profile investors in this round are Princeton, N.J.-based NRG Energy, Inc. and Fisher Brothers. Eos is NRG’s first investment in the energy storage industry.

Fisher Brothers is a privately owned New York City-based real estate firm which also owns Plaza Construction, a contractor with experience building urban power plants and renewable energy projects. Fisher Brothers is also a co-sponsor of the City Investment Fund (with Morgan Stanley), a founding member of Perella Weinberg Partners and a founding partner of Convergent Energy + Power, an energy storage asset development company with a pipeline of projects in New York, California and elsewhere.

Eos is actively raising capital for its Series C investment round to fund the production and delivery of Aurora energy storage systems to its utility partners in 2014.



Let's see...

$160/kWh @ 70% average DoD = $230/kWh used.
Assume 1 daily cycle, 20 year amortization, 7300 cycles over 20 years.
Cost of capital 5%, ROI 10%, 20% equity.
I get 7.8¢/kWh for storage, which is less than the peak/night price swing on the spot market in many places.

This looks like it will work in the market w/o subsidies.


Thanks for the calculations. :-) One question: Where did you get the 70% DoD? Is that fairly standard on Zinc Air? I'm just not as familiar with it.


This seems to be the type of innovation that the Fed. should support together with and in the same way as) private inventors?


On their website they are claiming better than that:

They claim 30 years and 10,000 'true cycles' which they define as a full charge, discharge and additional frequency regulation over the course of one full day.

I doubt they are talking about 100% DOD, but they seem to be indicating that they are doing a lot better than 70%, at least over the course of a day.
It appears that they are looking at part cycles cumulatively adding up to a bit more than 100% of nominal capacity over a day, to give a 'full cycle' rating of 10,000.

Since especially with renewables you are talking about a lot of fooling around every time a cloud passes over the sun, or the wind drops/gusts their assumption seems reasonable:

So the figures should be a bit better than those you laid out, perhaps around 6 cents/kwh


I'm assuming 70% DoD average because any sensible system will have a reasonable amount of margin built in.

If they can use more than 100% of the kWh capacity per day, cost drops along with it.  5¢/kWh isn't unreasonable with > 1 cycle/day.  But if it's used to buffer cycles of several days (e.g. the cycle of wind power driven by frontal passages), it goes up.

This appears to favor nukes, PV and maybe tidal power.


Buffering week long lulls in the wind is a renewables pipe dream.
It can't be done with any reasonable amount of storage, back up coal and gas have to be fired up.
That is not going to restrict sales of these batteries though, as they are ideal for dealing with the shorter-term wild swings in renewable output, not to mention normal peaks in diurnal demand.
They could also buffer solar for night time use, but of course would do nothing for annular variation.

Check out the link I gave for the hideous problems that renewables are giving the German grid, and the European grid in a knock-on effect.

There is plenty for these batteries to do short of coping with a real lull in the wind over an extended period.

There is plenty for these batteries to do short of coping with a real lull in the wind over an extended period.

No argument here, but recognizing how the per-kWh cost varies with the application and consequent duty cycle is important for clarifying issues.

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