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Aquion Energy takes plunge into bulk grid storage

A Carnegie Mellon spinoff seeks to raise $30 million in venture capital to pursue cheap storage for wind and solar power with sodium ion batteries.

To make a cheap battery that stores wind and solar power, Aquion Energy is using the ingredients in salt and water.

A spinoff out of Carnegie Mellon, the start-up has raised $20 million of a planned $30 million funding round, according to a regulatory filing spotted by Earth2Tech. The company was originally funded with $5 million from the federal stimulus program by the Department of Energy and has added Kleiner Perkins Caufield & Byers as an investor.

Aquion Energy's battery packs will be built from modular components and designed specifically for grid storage.
Aquion Energy's battery packs will be built from modular components and designed specifically for grid storage. Aquion Energy

Aquion Energy is developing a room-temperature sodium ion battery as an alternative to lithium ion and other batteries for grid storage. It expects to start making its refrigerator-size battery packs for customer testing later this year or next year, according to the company.

One of the advantages of sodium ion batteries is cost. Sodium, one of the ingredients in salt, is far more abundant than lithium. Aquion Energy's batteries use a water-based electrolyte, which is easier to work with and simplifies the manufacturing process, company founder and Carnegie Mellon material science professor Jay Whitacre told Technology Review.

Sodium sulfur batteries are one of the preferred technologies for storing wind and solar power or other grid applications. But sodium sulfur batteries run at high temperatures, making them less energy efficient and safe than ambient-temperature batteries, according to researchers at the Pacific Northwest National Laboratory working on sodium ion batteries. Lead acid batteries, meanwhile, result in the release of toxic lead, Whitacre's patent application notes.

In a presentation, Aquion Energy said that its battery will be 85 percent efficient and use non-toxic materials. The anode is made out of a "low-cost, high-performance" carbon and the cathode is made from manganese oxide. As happens in other battery chemistries, sodium ions move between anodes of the battery through the water-based electrolyte during charging and discharging.

The company's product plans are to use low-voltage cells strung together for grid-level storage. A battery pack the size of a data server rack would operate between 12 volts and 48 volts. Strung together into a shipping-container-size box allows for 500-volt to 1,000-volt batteries.

After testing its devices with customers, it plans to ramp up manufacturing in the 2013 and 2014 time frame. Its target price is under $300 per kilowatt-hour, which is well below the price of today's lithium ion batteries.

Feeding power into the grid for several hours has proven to be one of the toughest technical challenges in energy storage. Lithium ion batteries, which are good at providing bursts of power, are being used to "firm" up wind energy but cost remains a barrier.

The bulk grid storage area, which would allow several hours of storage for solar and wind, has attracted many researchers and companies. One example is Liquid Metal Battery, which recently was funded by Bill Gates and oil company Total, to develop cheap, long-lasting grid storage.