Rolling electricity blackouts occurred across Greene County throughout the day Friday as temperatures plunged into the single digits.Â
The Tennessee Valley Authority ordered Greeneville Light and Power System to institute the rolling blackouts due to the loss of numerous power generating assets and high energy use caused by extremely cold temperatures in much of the southeast.
"They have asked us to do rolling blackouts for 5% of our customers," Greeneville Light and Power President and CEO Chuck Bowlin said Friday morning. "We have a pre-determined plan that we are executing that is accomplishing that."
The blackouts began at about 10:45 a.m. Friday and continued until about 12:45 p.m.Â
The outages lasted about 20 minutes in each area. One area would experience a blackout for about 20 minutes before the blackout switched to another area of the county.
Bowlin said that the blackouts were being accomplished by opening certain breakers at local substations for a period of time, before closing them and opening others.
"The goal is keeping 5% of our power load off," Bowling said.
While the rolling blackouts were scheduled to continue until at least 2 p.m., Greeneville Light and Power System halted its rolling blackout schedule at about 12:45 p.m. on Friday after the Tennessee Valley Authority withdrew its blackout order.
"TVA has terminated their order to curtail load," Bowlin said Friday. "Everything has been restored and we are not going to continue the blackout schedule."
Bowlin and GLPS officials had a conference call at 1 p.m. Friday with TVA officials and were given more information about what caused the blackouts and if any more really blackouts would be necessary.
"The bottom line is they ended up losing a significant amount of generation assets at about midmorning. Then combine that with a higher peak usage than they anticipated and low reserves because they couldn't buy power from other companies. Every other utility was having the same issues they were," Bowlin said after the call with TVA. "That's why they ordered the curtailment to avoid bigger problems."
Bowlin said that TVA lost generation from multiple plants.
"It was over 6,000 megawatts of generation that they lost access to," Bowlin said. "To put that in perspective, one nuclear plant generates about 1,200 megawatts."
Tennessee Valley Authority was in the process of getting every plant back online and generating Friday afternoon.
"Some of those plants are back online now and they are working to get others back on," Bowlin said.
Bowlin said TVA did not say which plants went out of commission, but they did specify it was not due to weather issues at any natural gas plant.
"With gas generation things can freeze up with cold weather, but they specifically said that was not the cause," Bowlin said.
Natural gas plants and nuclear plants make up the largest portion of TVA's energy production mix that also includes hydro, coal, wind and solar.
The extremely cold temperatures in the region pushed TVA's plants to produce as much power as possible to keep up with customer demand, and Bowlin said maintaining that high level of generation in a plant can cause issues.
"In a situation like this, their plants are producing all out, and if something goes wrong or something overheats, it drops the whole thing out," Bowlin said. "They were already stressed to start with."
More blackouts are unlikely, according to Bowlin. However TVA did not rule them out entirely as temperatures are expected to remain in the single digits to teens into the weekend.
Tennessee Valley Authority planned to monitor energy usage levels closely, particularly at 7 p.m. Friday and 9 a.m. Saturday, according to Bowlin. Those times are when TVA expected usage to peak and put the most strain on the power system.
"They were not 100% confident that it might not happen again," Bowlin said. "They did not eliminate the possibility but put it at a fairly low level. They said a low probability."
The Tennessee Valley Authority released a statement Friday addressing the blackouts and providing tips to decrease energy consumption.
"With temperatures on Friday, December 23, averaging in the single digits across the region, the Tennessee Valley Authority and local power company employees are actively working to maintain a stable power grid for everyone amid unprecedented demand," the statement says. "To help ensure the continued reliability of the regional power system, TVA and local power companies are proactively taking steps to temporarily reduce power supplies to localized areas. These actions may create short, temporary power outages in certain areas."
A list of tips were provided in the statement to reduce power use "without compromising personal safety."
According to TVA, some simple methods of reducing power include lowering thermostats, delaying laundry chores or dishwasher use, and opening shades on sunny sides of homes.
"Lower thermostats by just one or two degrees – public safety is of utmost importance during dangerously cold weather, so don’t make big adjustments but every degree can help save on future power bills," the release says. "Delay doing laundry or running a dishwasher until the warmest part of the day, and turn off unnecessary lights and electronics, and open window coverings on the sunny side of homes and offices to let the sun heat your home, but close window coverings when the sun isn’t brightly shining."
The Tennessee Valley Authority apologized for the disruption in electrical service on Friday and noted they would continue to closely monitor the situation. The power company is also optimistic that expected slightly warmer temperatures will arrive throughout the weekend and take stress of the power grid.
"We apologize for the disruption that we know these actions may cause, especially during the holidays. They are difficult but necessary steps to prevent to potential of far greater power disruptions to the broader region," the statement says. "Slightly warmer temperatures filtering into the region this weekend should help minimize additional strain on the power system. TVA and local power companies will continue to monitor the situation and communicate any additional needed information."
