NASHVILLE, Tenn. (WKRN) — The Tennessee Valley Authority says officials are still investigating what caused unprecedented blackouts across Tennessee before Christmas, but activists fear TVA’s decision to replace its Cumberland Fossil Plant with a natural gas plant won’t help prevent power outages in the future.

“We saw gas pressure drop. Gas does not do well in freezing temperatures,” said Amy Kelly with the Sierra Club.

While Kelly and others say a natural gas plant emits less carbon dioxide than a coal plant, they wish TVA had used the closing of the fossil plant as an opportunity to diversify their energy sources and concentrate on renewable energy like wind and solar.

“TVA is actually moving away from diversification and investing more in gas which makes their system weaker,” Kelly said.

It’s a point that Jim Rossi, an energy law expert at Vanderbilt University, agrees will harm Tennesseans in the years to come.

“You don’t want to over-invest in any one resource,” Rossi said. “Resilience would be the ability to produce energy even when the water input to a natural gas plant or nuclear gas plant is completely frozen.”

According to TVA, nuclear, gas and coal make up 87% of their energy portfolio, and solar and wind make up 4%.

“In comparison to its peer utilities across the country [TVA] is under-invested in renewable energy,” Rossi said.

Rossi said that had TVA built up a more diverse energy portfolio, the rolling blackouts in December might have been avoided.

“If for example, TVA had worked together with NES to build up a portfolio of perhaps as much as 10% renewable energy for the city of Nashville that 10% reduction we were asked to take wouldn’t have been necessary,” Rossi explained.

He was also concerned that because a lot of infrastructure like pipelines and turbines is needed for a natural gas plant this move would lock TVA into using one energy source even as the efficiency of other sources will continue to improve.

TVA says the move not only helps them keep up with increased demands for energy but also will reduce carbon emissions at the site by 60%.

“Replacing retired generation with a natural gas plant is the best overall solution because it’s the only mature technology available today that can provide firm, dispatchable power by 2026 when the first Cumberland unit retires – dispatchable, meaning TVA can turn it off and on as the system requires the power, ”said Jeff Lyash, TVA president and CEO. “In addition, natural gas supports continued reduction of carbon emissions by enabling the integration of renewables, such as solar and battery storage, all while maintaining system reliability.” 

TVA says the Cumberland Fossil Plant will be taken offline in two stages. The first unit will be retired by the end of 2026 and the second by the end of 2028; however, what will replace the second unit hasn’t been decided at this time.