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.
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
"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
"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