Fixing the Power Grid

Big batteries will fight blackouts and could make renewable power economically viable.

Large-scale power storage is crucial to our energy future: the Electric Power Research Institute, the U.S. utility industry's leading R&D consortium, says that storage would enable the widespread use of renewable power and make the grid more reliable and efficient. Recent announcements by utility giant American Electric Power (AEP), based in Columbus, OH, suggest that grid storage technologies are finally ready for commercial deployment in the United States. Last month, AEP ordered three multi-megawatt battery systems and set goals of having 25 megawatts of storage in place by 2010, and 40 times that by 2020.

"That was a dream four or five years ago; now it is happening," says AEP energy-storage expert Ali Nourai.

The AEP system uses a sodium-sulfur battery about the size of a double-decker bus (see below), plus power electronics to manage the flow of AC power in and out of the DC battery. Though new to the United States, the system has been used at the megawatt scale in Japan since the early 1990s; the battery was produced by NGK Insulators of Nagoya, Japan.

Charging Charleston: The utility American Electric Power (AEP) deployed this huge sodium-sulfur battery as part of a demonstration project in Charleston, WV. The battery provides 1.2 megawatts of power for up to seven hours, easing the strain on an overloaded substation. Trouble-free operation since installation last year convinced AEP that such energy-storage technology is ready for active duty.
Credit: AEP

Nourai says that AEP and other U.S. utilities gained confidence in the economics and reliability of storage thanks to a demonstration project in Charleston, WV, where AEP installed a large battery system in June 2006. In Charleston, peak demand in both summer and winter had overloaded transformers at local substations, causing blackouts. Rebuilding the substations to accommodate more power could have taken as much as three years. Instead, AEP spent just nine months installing a battery system that charges when demand for electricity is low and can deliver up to 1.2 megawatts for seven hours when demand peaks.

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Two of AEP's new projects are slightly larger two-megawatt, seven-hour battery systems designed to provide similar quick fixes in areas with power-reliability problems. A battery in Milton, WV, for example, will provide backup electricity for customers in areas prone to blackouts from a weak power line. "When there is a blackout, the battery will pick up as many people as it can and continue to feed them," says Nourai. "They will not even know there was a blackout." The battery will postpone Milton's addition of a new substation and a high-voltage transmission line by five to six years.

When AEP decides to make more permanent upgrades to substations or completes construction of a new power line--a process that can take five or six years--it will simply move the nearest backup battery to another choke point. "It can be lifted with a forklift and loaded onto a flatbed truck," says Nourai. "Within a week we can have it up and operational at another site in our system."