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Texas Pioneers Energy Storage in Giant Battery

ADIT, avril

The sodium-sulfur battery system being installed in Presidio, Texas, will be the largest such energy storage array in the United States.
Photograph courtesy Electric Transmission Texas

Henry J. Reske
National Geographic News
Published March 25, 2010

     Presidio, Texas, has one link to U.S. electrical power, stretching some 60 miles (100 kilometers) from Marfa in the high desert to the banks of the Rio Grande.
     Built in 1948, the transmission line was around when Rock Hudson, Elizabeth Taylor, and James Dean walked Marfa's streets while filming the epic movie Giant.
     Electrical storms erupt frequently in the rugged expanse between Marfa, nearly one mile (1,600 meters) above sea level, and Presidio, on the Mexico border, "one of the hottest places in the nation," in the words of city administrator Brad Newton. "It really creates a situation unique to our geographic area," he says.
     Reliance on a single aging, transmission line in this hostile terrain has made life in Presidio different than in most of the United States.
     Chronic power outages and electrical fluctuations have been the norm.
     And sweltering in the dark has been only part of the problem. The situation wreaks havoc with electrical devices, causing computer systems to reset frequently—an annoyance in homes and a constant worry for authorities.
     "The area is a significant border crossing and for them to lose computers was not a good option," said Calvin Crowder, president of Electric Transmission Texas, LLC, a joint venture between subsidiaries of American Electric Power and Warren Buffett's electricity company, Berkshire Hathaway's MidAmerican Energy Holdings.
     ETT is just completing installation of a system designed to resolve Presidio's power woes.

Texas-Size Battery
     The hoped-for remedy is a battery, a Texas-size battery, which could eventually end up playing an important role in wider use of green power generation such as solar and wind. The U.S. $25 million system, which is now charging and is set to be dedicated April 8, will be the largest use of this energy storage technology in the United States.
     The four-megawatt sodium-sulfur (NaS) battery system consists of 80 modules, 8,000 pounds (3,600 kilograms) each, constructed by the Japanese firm NGK-Locke. They were shipped to Long Beach, California, in December and transported to Texas aboard 24 trucks.
     The cost of the battery system includes $10 million just to construct the building in which it will be housed and the new substation it requires.
     Sodium-sulfur batteries are not as well known as the now-ubiquitous lithium-ion batteries that power laptops and cell phones, but they are by no means new.

     Massachusetts Institute of Technology professor Donald Sadoway explains that the technology was, in fact, invented in the United States.
     "It was used by Ford in an electric vehicle in the early 1990s," he said. "The all-electric Ford Escort was powered by sodium–sulfur batteries made in Heidelberg, Germany".
     "It worked, but the technology was too expensive. They made maybe a hundred that were not for sale." (Sadoway, a battery design specialist, actually got a chance to drive the concept vehicle, which he recalls was "a real blast.")
American Electric Power (AEP) first tested the NaS system for stationary power at its Dolan Technology Center near Columbus, Ohio, and deployed it in a demonstration project in Gahanna, Ohio, in 2002. Since then, AEP has installed four NaS battery systems in West Virginia, Indiana, and Ohio.
     NaS looked like a solution that would work for Presidio. Also, it is part of a larger modernization project that includes plans for a new 60-mile (100-kilometer), 69-kilovolt transmission line from Marfa to Presidio at a cost of $45 million, to be completed by 2012.
     As such, the cost of the battery system will be shared by all 22 million customers on the Texas electricity grid. Members of the state legislature, Presidio officials, ETT and AEP Texas petitioned the grid operator, the Electric Reliability Council of Texas, to approve the project, labeling it a certified need.
     The plan also needed and obtained approval of the Public Utility Commission of Texas.
     Even when the transmission line is modernized, Crowder said the battery system will still be essential for Presidio.
     Despite the latest in lightning arrestors, controls, and switching, the new line will not be immune to the fierce storms spawned on the plains.

Fast Response Time
     The battery system will have a fast response time to address voltage fluctuations and momentary outages. And it also is designed to supply uninterrupted power for up to eight hours. This is not only crucial in the event of an outage, but it will assure that the lights stay on if Presidio needs to tap power from across the border in Mexico, as the city sometimes does during emergency situations—a switchover process that can take hours.
     Crowder predicted that as those who are in the business of generating energy watch what ETT is doing, there will be "more and larger deployments in use of battery storage for wind and solar."
     "This type of technology as a utility application is still fairly new in the United States," Crowder said. "Japan has been at this for a decade or so. As we learn more and as the price becomes less through mass production, there will be opportunities for wind and solar to improve the economics of their power."
     MIT's Sadoway, a professor in materials chemistry, said that many of NGK's systems, indeed, are in use in Japan. But he said batteries as backup for solar is still far too expensive.
     "I'm excited that people are embracing battery storage at this scale," Sadoway said. "Once utilities get experience at what a large storage facility can do for them, eventually we will come up with technology that is cost-effective and a benefit for all."