The Tennessee Valley Authority had a record-setting power week in January, making use of the millions of dollars the agency invested on weatherization and new natural gas plants to get through a week-long winter storm and deep freeze.

A diverse mix of sources, built on the foundation of nuclear power, got the federal utility through its highest-ever power demand on Jan. 17, its highestever weekend power demand on Jan. 21, and its highest amount of power delivered in one week.

The energy sources used during the storm also reflect TVA’s move toward natural gas and away from coal plants, which failed it during Winter Storm Elliott in 2022 and have gotten more expensive as they age.

In extreme weather events, it’s “all resources on deck,” said Aaron Melda, senior vice president of power supply operations at TVA. Melda told Knox News the agency’s operators were thankful as last month’s winter storm arrived that new natural gas plants can withstand cold temperatures.

“Those coal sites are like you’ve got a ‘78 Buick in the driveway,” Melda said. “Bringing on these newer natural gas sites, it’s simply like buying a new car. The inherent reliability of those facilities are going to be better just because they are newer.”

Melda said TVA will continue to invest in extending the lives of its nuclear plants and hydroelectric dams, two of its most reliable power sources.

Where did TVA gets its energy during the record-breaking week?

More vital in extremely low temperatures than its diverse energy mix was the $123 million TVA spent since the blackouts of Winter Storm Elliott to ready its plants for another winter storm, including millions spent on heating technology.

TVA is able to generate close to

33,000 megawatts with all cylinders firing. It can also purchase thousands more megawatts from neighboring utilities.

During Jan. 15-21, the utility purchased about one-sixth of its power and used all its available generating sources, Melda said. Only 3% of TVA’s fleet was unavailable during the week’s peak power demands.

Here’s the breakdown of where that power came from over the week:

● 30% nuclear

● 26% natural gas

● 16% coal

● 11% hydroelectric

● 17% purchased power

The ratio of electricity produced over the frigid week differs from the ratio of general capacities of various sources, which TVA reported in its latest annual SEC filing in November 2023:

● 42% nuclear

● 22% natural gas

● 13% coal

● 8% hydroelectric

● 15% purchased power

Though nuclear accounts for 42% of TVA’s generating capacity, the utility’s three nuclear plants don’t contribute to that capacity at every moment of the week, Melda said.

TVA trades old coal plants for new gas plants

TVA’s shift away from coal and toward natural gas continued between December 2022 — when it ordered its first rolling blackouts — and the January 2024 storm.

Since 2012, TVA has closed seven coal plants, and placed natural gas generators at five of the sites.

The agency retired the Bull Run Fossil Plant on Dec. 1, 2023, and three new natural gas units at the Paradise Combined Cycle Plant in Kentucky came online a month later, adding 750 megawatts of generation built to withstand low temperatures.

Along with three units that came online in July 2023 in Alabama, TVA added almost 1,500 megawatts of natural gas generation.

The Bull Run plant in the Claxton community of Anderson County failed to start generating during Winter Storm Elliott, exposing the weaknesses of TVA’s aging fleet of coal plants.

The average age of the remaining coal plants — Cumberland, Gallatin, Kingston and Shawnee — is about 60 years old, though they were built to run about 40 years. TVA plans to shutter all of them by 2035.

Another problem with coal for TVA is a growing set of federal regulations on the dirty fuel, which make modifying old plants too expensive to be worth it, Melda said.

“Increasing federal standards are requiring additional equipment be added on what is already an old facility, and the finances don’t work out, extending those lives versus bringing new new plants online,” Melda said.

Natural gas also is a fossil fuel, but it emits less carbon than coal. Gas plants can be built in the footprint of coal plants, a model TVA leaders say is a bridge to a cleaner energy future.

TVA has a geographical advantage in the natural gas supply chain, which can drastically affect revenues if gas prices soar. It is positioned between the Marcellus shale formation to the north, where gas is extracted through fracking, and the Gulf of Mexico to the south.

To meet population growth and to make best use of a reliable natural gas supply, spurred on by controversial fracking technology, TVA is building more gas plants. It will replace the Cumberland Fossil Plant, its largest coal plant, with a 1,450 megawatts natural gas plant scheduled to come online in 2026.

Which records did TVA break during the 2024 winter storm?

January’s winter storm was notable not only for the volume of snow and frigid temperatures, between 6.5 and 10 inches in the Knoxville area, but also for how long the snow stuck around, a record seven consecutive days with 4 or more inches of snow on the ground.

At 9 a.m. Jan. 17, as temperatures hovered near 0 degrees in Knoxville and averaged 4 degrees across the Tennessee Valley, TVA withstood a record power demand of 34,524 megawatts, according to preliminary data. That’s enough electricity to power more than 20 million average homes at once.

At 9 a.m. Jan. 21, the utility had a record weekend power demand of 34,284 megawatts.

Over the week of Jan. 15-21, TVA delivered 4,792 gigawatt hours of energy, a record for a seven-day period. A gigawatt is equivalent to 1,000 megawatts, and a gigawatt hour is a measure of energy use over one hour.

The U.S. Energy Information Administration, the statistical arm of the Department of Energy, independently gathers energy data, though its data is not validated by utility companies.

During the record power demand on the morning of Jan. 17, the Energy Information Administration tracked how much power TVA’s fleet was producing:

● Nuclear: 8,523 megawatts

● Natural gas: 10,403 megawatts

● Coal: 4,642 megawatts

● Hydroelectric: 5,085 megawatts

● Other: 1,432 megawatts

● Solar: 53 megawatts

TVA has purchase contracts for 715 megawatts of solar and another 1,867 megawatts under contract but not yet operating, according to 2023 SEC filings. It plans to add 10,000 megawatts of solar generation by 2035, which delivers relatively cheap energy when the sun is shining.

Daniel Dassow is a growth and development reporter focused on technology and energy. Phone 423-637-0878. Email daniel.dassow@knoxnews.com.