For the first time in its 89-year history, the Tennessee Valley Authority had to limit its power delivery and impose rolling blackouts for some of its customers on Friday when the federal utility lost generation from its biggest coal plant and several natural gas combustion turbines were unable to perform during the coldest weather in more than a decade.
TVA temporarily activated the highest level of its emergency load curtailment plan Friday, forcing many of the 153 municipal utilities and power coops that buy TVA power to immediately curtail their power use by 5% or be hit with rolling 15-minute blackouts in some areas. The move was forced when both units at TVA's Cumberland Fossil Plant shut down and several gas-powered units also failed to operate when high winds and frigid temperatures combined to damage some of the instrument lines and equipment for the plants.
TVA Chief Operating Officer Don Moul said Friday that TVA is working with its local power companies and customers to help limit power demand while also moving to restore generation at Cumberland and other sites. TVA imposed rolling blackouts for some of the local power companies for a couple of hours on Friday but was able to end those blackouts after temperatures rose and demand slowed Friday afternoon.
(READ MORE: How to stay safe and warm as freezing weather approaches the Chattanooga area)
"We continually invest in our system and plan for extreme weather conditions, but this historic arctic weather has been worse than we anticipated," Moul said in a telephone interview late Friday. "We never want to have to interrupt service to our customers, but we have these emergency measures so we can systematically reduce load and maintain the stability of the electric grid overall."
Preliminary reports indicate that TVA's peak power demand Friday morning topped 32,000 megawatts, and the utility was bracing for a similar peak Friday night and early Saturday when the temperature in Chattanooga is projected to drop to the lowest in eight years.
With nearly 20% of its power generation idled at one point, TVA struggled to meet the high demand for electricity in the Tennessee Valley, where more than 60% of all homes and businesses rely upon electricity for heating in the winter.
"Extremely cold temperatures across the region are creating unprecedented demand on the power system," TVA said in an "important message" posted on the utility's Facebook page Friday. "We are asking businesses and the public to help by immediately reducing electric power use as much as possible without sacrificing safety."
Temperatures in Chattanooga dropped Friday morning to 7 degrees Fahrenheit -- the coldest temperature in Chattanooga since 2014, according to the National Weather Service. Afternoon temperatures Friday were expected to reach only about 12 degrees and drop Saturday morning to 6 degrees Fahrenheit.
The arctic storm and its high winds knocked out power to homes and businesses throughout the country on Friday. More than 100,000 customers of Georgia Power lost electricity service Friday morning, although power was restored for most of those affected later in the day.
Nationwide, power outages left about 1.4 million homes and businesses in the dark, according to the website PowerOutage, which tracks utility reports.
On Friday morning, TVA implemented cutbacks for customers with interruptible service contracts that allow for power cutbacks during peak demand periods in exchange for lower base rates. Later in the day, Moul said such customers were given a window of time without the interruption, if they needed it.
With schools and some businesses closed over the holidays, TVA was still short of its all-time power peak of 33,482 megawatts reached during a summer heatwave on Aug. 16, 2007.
(READ MORE: Senate confirms Biden nominees for TVA to restore utility board to full 9 members)
In Chattanooga, EPB's power demand rose Friday to 1,158 megawatts -- the highest peak demand since 2018. EPB's all-time power peak was in 2014 at 1,348 megawatts, EPB spokesman J.Ed. Marston said in a text message.
EPB spokesman Sophie Moore said in a statement that the Chattanooga utility was able to achieve TVA's 5% reduction in load Friday by working to limit its own energy use and those of major industrial and commercial customers and avoid having to interrupt power to its residential customers.
"Because EPB has a different customer mix than some of the other power distributors, we believe we will be able to reach TVA's target by working individually with large customers and hope to avoid the need for rolling blackouts," Moore said.
With temperatures forecast to remain below freezing in Chattanooga through Christmas Day on Sunday, EPB is urging customers to limit their electricity consumption.
"Public safety is our overriding priority, so do not significantly turn down your heat, but lowering thermostats by just one or two degrees makes a big difference,' Moore said.
Other steps being encouraged for residential customers to limit power use include:
-- Delay using washing machines, dryers, dishwashers and high-energy-use appliances until later on Saturday afternoon.
-- Keep window coverings closed on the nonsunny side of homes but open them if bright sunlight is available to provide additional heat.
-- Turn off and unplug unnecessary appliances and electronics.
-- Delay using large appliances and electronics.
(READ MORE: Chattanooga's EPB Energy Pros help you save on your electric bill)
"In the spirit of the holiday season, we are asking for everyone's help in ensuring the power grid remains stable for us all," TVA spokesman Scott Brooks said in a statement.
Allan Diegan, a meteorologist with the National Weather Service in Morristown, Tennessee, said temperatures in Chattanooga are expected to remain below freezing through Christmas Day on Sunday.
"This is a very strong cold front with arctic air behind it and that brought gusty winds that lowered the windchill in Chattanooga down to negative 11 degrees (early Friday)," Diegan said in a telephone interview.
Contact Dave Flessner at email@example.com or 423-757-6340.