Battery-backed homes could energize smart grids

Storing electricity on a large scale has been deemed impractical for more than a century, but it is now within reach as the nation's power companies develop smart grid technologies.

Duke Energy has been testing battery power storage in Charlotte for the past year and Progress Energy is also planning to test industrial batteries in this state soon.

Officials from both companies briefed utility regulators last month on the potential of battery storage as part of their smart grid strategy. The transcript of the Jan. 26 presentation was released Friday by the N.C. Utilities Commission.

Batteries would back up intermittent energy resources such as solar power and wind power, by storing the clean electricity until it is needed during times of peak energy demand.

"Individual home battery storage units may become quite popular as we move forward," said said Rebecca Harrison, director of Progress Energy's Smart Grid Program. "If you have a photovoltaic system on your house, you could also have battery storage, which would make that a much better combination."

Large-scale adoption of batteries is still 7 to 10 years away, as new technologies are developed and prices come down, Harrison said.

One potential source for the batteries could be electric vehicles, she said. As car batteries are become less efficient over time, they could be used to create a backup storage unit for a rooftop solar array, which wouldn't require the high performance of an automobile battery.

The nation's first commercial plug-in vehicle, the Chevy Volt, is expected to become available this year, and other automakers will follow with their own models.

"They're going to look at repacking those batteries for a home storage unit," Harrison told the Utilities Commission. "There's been a lot of movement in the last couple of years in this area."

The term smart grid refers to an automated, digital power delivery network that will eventually replace the nation's aging electro-mechanical grid.

By using advanced meters with two-way communication, the smart grid will let power companies provide services they don't offer today, such as remotely shutting off and turning on power, pinpointing power outages to each affected home, giving customers pre-pay options, and generating real-time streaming data on household energy use.