Electric Transmission Texas, LLC (ETT) dedicated the nation's largest, and Texas' first, utility-scale battery today during ceremonies in Presidio, one of the oldest cities in Texas.

The 4-megawatt NAS(R) sodium-sulfur battery system was energized March 31 to the Electric Reliability Council of Texas grid.

ETT is a joint venture between subsidiaries of American Electric Power (NYSE: AEP) and MidAmerican Energy Holdings Company.

The NAS battery system represents part of an approximately $70 million overall commitment by ETT to improve transmission reliability in Presidio and surrounding areas. The dedication ceremonies recognized installation of the new battery system and thanked local and state leaders for the support that helped achieve approval from the Public Utility Commission of Texas (PUCT).

Full utilization of the battery system, along with the recently completed Gonzales Substation, is expected to begin by this summer in time for summer peak usage. Cost of the battery and substation is approximately $25 million. A 60-mile, 69-kilovolt transmission line from Marfa to Presidio is targeted for completion by 2012 with an estimated cost of $45 million. In March, ETT filed an application with the PUCT requesting a Certificate of Convenience and Necessity authorizing construction of the transmission line.

In the meantime, the NAS battery system will provide transmission backup in the event of a transmission line outage. The battery system also is designed to improve power quality and reduce voltage fluctuations.

"Very soon, one of the oldest cities in the United States will begin benefiting from one of the world's newest technology developments," said Calvin Crowder, ETT president. "This battery installation will enhance electrical service for our customers in this region, and completion of this milestone will allow the Presidio area to realize its full benefits by this summer."

The NAS battery system installed in Presidio will provide the following benefits:

- Due to its quick response, the battery will address voltage fluctuations and momentary outages.

- In the event of an outage on the radial transmission line providing power to Presidio, the battery can supply four megawatts of uninterrupted power for up to eight hours.

- The battery will allow Presidio's electrical load to receive uninterrupted power from Comision Federal de Electricidad (CFE) during emergency situations. - The battery will allow for maintenance on the new transmission line being built from Marfa to Presidio without loss of electric service.

The battery modules were transported by ship from NGK-Locke, Inc. in Japan and delivered to the Port of Long Beach in December 2009. Twenty-four trucks were then used to carry the 80 modules and ancillary equipment from California to Marfa, Texas, where they were stored until construction of the concrete building that now houses the battery system was completed. The modules were moved to Presidio in February, and installation activities began at that time.

The battery system is controlled through an S&C Electric Company Smart Grid Storage Management System(TM), a fast-response, automatic power converter and controller that provides the ability to store energy in a variety of battery storage technologies and to control the discharge of that power into the electrical grid.

AEP pioneered the use of the NAS battery in the United States. Following testing at its Dolan Technology Center near Columbus, Ohio, AEP became the first U.S. company to deploy NAS batteries when it installed and operated a demonstration unit in Gahanna, Ohio, in 2002. In 2006, AEP installed a 1.2-megawatt stationary NAS battery near Charleston, W.Va. In 2008, AEP installed three, 2-megawatt NAS batteries: one in Churubusco, Ind.; one in Balls Gap, W.Va.; and one in Bluffton, Ohio.

ETT acquires, constructs, owns and operates transmission facilities within the Electric Reliability Council of Texas, primarily in and around the AEP Texas Central Company and AEP Texas North Company service territories.

AEP, headquartered in Columbus, Ohio, is one of the largest electric utilities in the United States, delivering electricity to more than 5 million customers in 11 states. AEP (www.aep.com) has extensive experience building extra-high-voltage 765-kV transmission lines and owns the nation's largest electricity transmission system, a nearly 39,000-mile network that includes 2,100 miles of 765-kV transmission lines, more than all other U.S. transmission systems combined.

MidAmerican Energy Holdings Company (www.midamerican.com), based in Des Moines, Iowa, is a global provider of energy services to more than 6.9 million customers worldwide. MidAmerican Energy Holdings Company subsidiaries, PacifiCorp and MidAmerican Energy Company, own and operate more than 18,000 miles of electric transmission lines.

SOURCE Electric Transmission Texas, LLC

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