The popular claim is that everything is bigger in Texas. When it comes to utility-scale batteries, it’s no exaggeration, now that a 4-megawatt (MW) sodium-sulfur battery system is operational in Presidio, Texas. In the event of a transmission-line failure, the new battery is capable of powering the entire city of 5,000 for up to eight hours.

The 4 MW battery is 35 feet tall, 150 feet long and 35 feet wide. It contains 80 battery modules. Each slab is 46-by-90 inches and 14 inches high. The big battery and a supporting substation cost about $25 million.

“It’s new technology—the largest battery in the country and first in Texas,” said Larry Jones, corporate communications manager for American Electric Power Texas and spokesperson for Electric Transmission Texas.

“Since the battery began operation, it’s provided reactive power by reducing momentary outages caused by voltage fluctuations. We have remote capability if an outage occurs by switching it on from our center in Corpus Christi. We expect testing to be completed sometime in October, so the battery switches on automatically in the event of the transmission line failing that goes into Presidio,” Jones said.

The battery modules were manufactured by NGK-Locke Inc. in Japan and transported by ship to Long Beach, Calif. It took 24 heavy-haul trucks to move them to Presidio. They are controlled by an S&C Electric Co. smart-grid storage management system, a fast-response, automatic power converter and controller that stores energy in the batteries and controls discharge into the electrical grid.

American Electric Power is one of the largest utilities in the United States, delivering electricity to more than 5 million customers in 11 states. The big battery at Electric Transmission Texas is a joint venture between subsidiaries of American Electric Power and MidAmerican Energy Holdings Co.