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Two megawatts of batteries connected to power grid

Altairnano's lithium-titanate batteries get certified for short-term storage on electricity grid, an important test for new battery technology in grid applications.

Giant cousins of your laptop batteries are going to provide storage to the electricity grid.

Altairnano on Tuesday said that Indianapolis Power & Light, a division of utility AES, completed tests for using two megawatts worth of its batteries to maintain grid frequency.

Inside a semi-trailer that houses one megawatt of lithium-titanate batteries for grid storage. Altairnano

The two one-megawatt units--each housed in a semi-trailer--can store up to 15 minutes worth of electricity, or 250 kilowatt-hours each. (The average U.S. home consumes 920 kilowatt-hours per month.)

The tests are important because they demonstrated that lithium-ion batteries can be used for utility-grade energy storage. Right now, most short-term energy storage is done by lead acid batteries.

The certification also suggests that these types of batteries can be used for other grid applications, such as storing electricity from renewable energy sources.

"This two-megawatt validation project is one of the final steps in our move towards commercial deployment of grid-scale energy storage," Chris Shelton, director of energy storage development at AES, said in a statement. "Fast-responding, high-efficiency energy storage systems such as these will create a more resilient grid and allow for increased use of variable generating sources such as wind and solar."

Energy storage on the power grid, for the most part, is not widely done.

But there are a number of companies now pursuing that market in addition to Altairnano, which also makes batteries for plug-in hybrid cars.

Another battery upstart, A123 Systems, last month said that it is testing its lithium-ion batteries with utilities right now.

In addition to the need to develop utility-specific technology, energy storage--particularly for several hours or days-- faces a number of financial hurdles from risk-averse utilities.

Another utility, AEP, already has megawatt-class storage units from NGK Insulators of Japan installed on its grid and has a program to put 25 megawatts of storage on the grid this decade.

Update at 8:15 am PT on July 9: Correction to the last paragraph, stating that AEP already has a grid storage program in place.