Eos Rechargable Zinc-Air Battery: Energy Storage “El Dorado?”

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The dream of a “City of Gold” captured the imagination of a previous age. Today we search for a solution that will answer our aspirations for energy storage. We need energy storage for solar and wind resources. We need storage for peak shaving, frequency regulation. We need storage for electric vehicles. Lithium-Ion batteries are increasingly cost-effective with better energy density, however their future development is limited. The theoritical maximum energy capacity of present lithium-ion battery technology is not enough to give us the range we have come to expect from petrol vehicles. We will have to move, eventually, to a new battery chemistry to achieve increased energy density and range. Zinc-air holds a promising solution.

The Zinc battery that is non-rechargeable is what we most commonly use in our many portable devices. The anode tends to form dendrites, membranes destroyed and, when used with air, the air ports tend to become blocked by carbon dioxide. In yesterday’s 2GreenEnergy webinar, Craig Shields spoke to Steve Hellman president of Eos Energy Storage, (formerly Grid Storage Technologies) of Easton, PA about its “first ever long-life Zinc-air electrically rechargeable battery.” The secret to this discovery started in 2004 with a complete reworking of the way the battery is built.

Advantages of the Zinc-air battery start with its reduced volume. Other batteries must carry around cathode reactants where this battery needs only air. Zinc is a cheap and very common material, with the US, Canada, and Australia as primary producers. In a recent greentechgrid article, Michael Kanellos says, “The zinc/zinc oxide reaction is essentially infinitely renewable. By contrast, titanium and silicon oxide reactions can’t be reversed in the same way. Iron and lead have lower energy densities and lithium and sodium, which can pack quite a bit of energy, aren’t as stable.”

Several products are anticipated by Eos, such as the following:

The Eos Aurora 1000/6000 is designed for utility-scale energy storage and is delivered in a standard ISO 40′ shipping container (1MW/6MW-hr) for immediate deployment. There are no sub-components that need routine replacement, and the system is expected to last at least 10,000 true (full discharge) cycles, or about 30 years, with a cost of 1000/kW and $160/kW-hr. The cost does not include necessary inverters. Power supplied by this storage is expected to be less than gas turbine peaking plants at about $ .02 to $.06 /kW-hr. Product deliveries will begin in 2013.

The Eos Vista Zinc-Air Flow Battery is expected to be available after 2015. Anticipated energy density is around 100wh/kg, and 400wh/liter electrolyte can be removed and saved for re-conditioning. New electrolyte can be placed pumped into the battery and drivers can be on their way. Battery cost would be about $200/kW-hr. A Nissan Leaf with a 100-kW-hr Zinc-air battery might cost $8,000 less and have a range up to 340 miles. We could be well on our way to the city of Gold.

Photo via davidreber


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