This story was updated Wednesday, Aug. 14, 2019, at 10:55 p.m.

The hottest day of the summer Tuesday pushed electricity use in the Tennessee Valley to the highest peak in August in more than seven years.

TVA said Tuesday's peak demand for power reached 29,568 megawatts at 4 p.m., when the heat index across much of the seven-state TVA region topped 100 degrees, although the average temperature across the Tennessee Valley reached only 94 degrees due to scattered storms Tuesday afternoon and evening.

In Chattanooga, the high reached 100 degrees, with the heat index topping 109, according to WRCB-TV Channel 3.

TVA's power demand Tuesday was the highest August peak for the agency since Aug. 1, 2012. But TVA spokeswoman Malinda Hunter said Wednesday the utility met the peak without any request or implementation of conservation measures other than TVA's own internal suspension of most maintenance work on its power plants from 8 p.m. Monday to 8 p.m. Tuesday to limit the chances of any outages.

TVA has all seven of its nuclear reactors at full power and is relying on other output from its natural gas, coal, hydro and solar generators, along with its contracts for purchased gas, wind and solar power.

"We saw this heat wave a week out, so we were able to prepare in advance making sure that Tennessee Valley residents were able to stay cool," Patrick Walshe, TVA's transmission resource operations and analysis manager, said in a statement Wednesday.

(Read more: What you need to know to prepare for the extreme heat this week)

TVA's peak power demand Tuesday was still far below the utility's record power peak reached in the summer of 2007 when temperatures across the valley averaged 102 degrees and the peak demand jumped to 33,482 megawatts from heavy electricity consumption for air conditioners.

According to the Energy Information Administration, almost all Tennessee households use air conditioning equipment, with over 80% using central air conditioners and a small portion using window or wall units.

But improved energy efficiency of heat pumps, air conditioners, appliances and machines, combined with the closing of some major electric-powered manufacturers in previous years, have combined to cut overall power demand in the Tennessee Valley below the peaks reached before the Great Recession a decade ago.

TVA, which increased its electricity sales through most of its 86-year history, is now forecasting stable to declining electricity demand for the next two decades as the energy efficiency of machines, air conditioners and appliances continues to improve and distributed energy from solar, wind and other self-generated power increases.

Contact Dave Flessner at or 423-757-6340.