Tuesday, June 28, 2011

Power Grid


As the Tennessee Valley Authority continues to repair storm damage that temporarily knocked out some electricity distribution, the utility insists its transmission system is not fragile.
Republican U.S. Rep. Roscoe Bartlett of Maryland disagrees, contending the destruction and resulting blackout shows that the power grid is "very vulnerable. It's very much on edge."
TVA said on Monday that the storms cost the utility and its customers about $200 million, including the expense of buying replacement power. Average monthly residential billings will increase in July by up to $6 to pay for pricier replacement power during the repairs.
Andrew Phillips of the Electric Power Research Institute told the Chattanooga Times Free Press "it would be almost impossible" to build a transmission line able to withstand the powerful tornadoes that struck in Alabama, Tennessee, Georgia and Mississippi in late April.
The record-setting tornadoes took out 108 TVA power transmission lines and 353 of the utility's power towers.
For 22 straight days before Memorial Day, TVA's Travis Terry and his crew worked 16 to 18 hours a day, unsnarling the electric grid after tornadoes destroyed power towers and electric lines.
Since Memorial Day weekend, the crew has returned to that schedule. Terry said that with work at the Widow's Creek Fossil( FOSL - news - people ) Plant in northeast Alabama almost finished "we can see the light at the end of the tunnel, and we're tickled to death."
In one section of the power transmission right of way near Widows Creek, every line and tower for more than a mile was reduced to piles of twisted steel and cable. Fourteen power distributors and 847,000 homes and businesses were cut off from TVA power, leaving much of north Alabama and northeast Mississippi dark for a week. Even some reactor cooling systems for the Browns Ferry Nuclear Plant in North Alabama were affected.
James B. Sandlin, manager of the Scottsboro, Ala., Electric Power Board, said his city had little storm damage but for a time was at the mercy of TVA.
"I think it was a wake-up call for a lot of people, and we've started marketing home generators," Sandlin said. "But we had begun putting together an alternative plan as a utility several years ago." When TVA-supplied power went out, Scottsboro made some quick changes and used generators and its cable system to rotate power around town to its 8,500 customers in two- and three-hour daily blocks.
"It made a big difference to a lot of people," Sandlin said.
TVA and electric power generation industry groups don't think the tornado damage was avoidable or revealed problems.
"We do not believe our system is fragile," TVA spokeswoman Barbara Martocci said.
David Orr, an environmentalist and Pentagon climate change consultant who spoke in Chattanooga just after the tornadoes, said terrorism and climate change are dictating new needs for energy policy.
"Anything that is as centralized as our power grid, which takes power from one big place to many small ones, is vulnerable," he said. "We have to change the model."
Martocci said distributors are allowed to use their own generation to supply power when TVA can't.
She said it is "uneconomical for a distributor to keep a large amount of generation on standby for a storm that might happen once every 10 or 20 years."
Martocci said TVA's 99.999 percent reliability performance measure will not change because of the storm-related outages. The performance measure does not count storms because the utility can't control nature, she said.
She said the Knoxville-based utility with some 9 million customers in Tennessee, Kentucky, Virginia, North Carolina, Alabama, Georgia and Mississippi "will look at what happened during the storms and determine if there is a need to change anything to lessen our risk and damage."

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