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By Liz Enbysk

SGN Managing Editor

Few would argue that energy storage is going to play a key role in our energy future. Mandates for renewable energy portfolios alone make energy storage critical for load leveling against the intermittency of wind and solar. What isn't so clear is which energy storage technologies will emerge as the leaders when cost, reliability and scalability are all factored in.

Below are some intriguing contenders that caught our eye, followed on page 2 by three must-see reports on energy storage from EPRI, the Texas Institute and Zpryme.

Please pass the salt

Aquion Energy – a spinoff of Carnegie Mellon University – has raised $20 million to support its plans to produce a battery based on ambient-temperature, sodium ion technology that can handle stationary energy storage.  In other words, as Martin LaMonica explains in his CNet article, Aquient wants to use salt and water to produce inexpensive batteries that can provide grid-scale storage to hedge against the intermittency of wind and solar power.  Cost will reportedly be one of the advantages sodium ion batteries have over lithium ion.

With some juice from Bill Gates

With an investment from Microsoft co-founder Bill Gates among others and recently secured patent rights, Liquid Metal Battery is currently looking to commercialize its technology which was developed with funding help from ARPA-E and positioned for a role in grid-scale storage. As Popular Mechanics explains it, liquid metal batteries work pretty much on the same principle as any other battery:  "Two electrodes exchange electrons through an electrolyte to complete a circuit. But by using liquid metals for electrodes and molten salt as an electrolyte, their battery can absorb electrical currents that are 10 times higher than present-day high-end batteries."

Energy in the air at Woodstock

Woodstock, Minnesota, that is, where Juhl Wind intends to make use of a battery storage technology that uses zinc chemistry. Kalispell, Montana based Zinc Air Inc. will install a 1 MW advanced energy storage solution that will store and shift wind power for use by utility operators. According to the announcement, the zinc redox flow battery was developed "to achieve rapid payback periods while also being the greenest battery technology on the market."

Victory for vanadium

This spring, Washington, D.C.-based Prudent Energy won a grant from the California Public Utility Commission – in cooperation with SunPower, PG&E, KEMA and DOE's Sandia Laboratory – to build and operate its Vanadium Redox Battery Energy Storage System with SunPower's photovoltaic systems. According to Prudent, its "flow battery" system works like a rechargeable fuel cell, where chemical energy is converted to electrical energy at a moment's notice. The idea is to demonstrate how SunPower's solar customers can reduce energy costs by pulling in stored energy when the sun goes down but electricity rates and usage remain high.

Going with the flow

A new architectural twist on flow batteries from researchers at MIT and 24M Technologies could prove promising for both electric vehicles and grid storage. The new battery involves a semi-solid flow cell architecture – a unique design that separates the energy storage function of the battery and the energy discharge function into distinct physical structures that proponents believe could aid efficiency as well as size and cost. Read more about this use of semi-solid electrolytes in a flow battery in this Lux Research article.

A123 goes to China

As China strives to meet its government's ambitious goals for wind power, Watertown, MA-based A123 Systems is happy to oblige. Earlier this week the developer and manufacturer of advanced nanophosphate lithium-ion battery and energy storage systems announced a contract with China's third largest manufacturer of wind turbines, Dongfang Electric Corp. In its first foray in China, A123 will supply a 500kW advanced energy storage solution as a demonstration project to help DEC evaluate how advanced energy storage can address the challenges associated with the rapid growth of wind power.

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