The Tennessee Valley Authority’s plan to swap a retiring coal plant with a new natural gas facility is making progress despite opposition from environmental groups.

The Tennessee Department of Environment and Conservation (TDEC) in late July issued an Aquatic Resource Alteration Permit to Tennessee Gas Pipeline Co. The Kinder Morgan subsidiary is proposing to build a new methane gas pipeline across three counties in Tennessee to supply TVA’s proposed 1,450-MW Cumberland gas plant. (See Nonprofits Urge TVA to Reconsider Gas-fired Options.)

The newest permit paves the way for the Army Corps of Engineers to issue a Section 404 permit under the Clean Water Act and for FERC to move forward with its own permitting. On June 30, FERC issued a favorable, final environmental impact statement (EIS) for a natural gas pipeline to supply the plant.

Angela Mummaw of Appalachian Voices said she thought TDEC’s permitting process was rushed.

“They did not take the time to seriously consider the detailed comments they received. Community members and subject experts submitted hundreds of pages of concerns, and they made a decision just five days after the comment period ended,” Mummaw said in a statement. “There was no response about the new species of crayfish we discovered, or the stream that would be crossed three times in short succession, compounding the negative impacts of the open-trenching method that Tennessee Gas Pipeline Co. plans to use. Despite all the reasons we gave them not to, TDEC issued the permit anyway.”

Assuming the pipeline is fully permitted, TVA will be a customer for its proposed plant.

TVA plans to retire the first of two coal burning units at the 50-year-old Cumberland plant by the end of 2026 and expects to have the planned gas plant operating before then to replace production. The Cumberland Fossil Plant failed during the December 2022 winter storm, contributing to the rolling blackouts TVA was forced to authorize.

“Natural gas is an important part of our energy system of the future. It offers flexibility to meet load demand as we add more generation, like solar power, to the mix without risking reliability and grid stability,” TVA spokesperson Elizabeth Gibson said in an emailed statement to RTO Insider.

The Sierra Club, Appalachian Voices and the Center for Biological Diversity, represented by the Southern Environmental Law Center, filed a lawsuit in mid-June in U.S. District Court in Nashville hoping to stop TVA’s plans to substitute one fossil fuel for another.

The lawsuit claims TVA defied the National Environmental Policy Act by committing to a new natural gas plant too early in the process, failing to seriously consider carbon-free alternatives and ignoring the climate harms and volatile fuel costs the community will bear. The groups allege TVA signed a contract with the pipeline company before completing the requisite review.

“We know that renewables with battery storage and robust energy efficiency continue to beat out fossil fuels in cost around the country, so a federal agency should be held accountable when it fails to meet the most basic requirements of the National Environmental Policy Act,” Sierra Club’s Amy Kelly said in a statement at the time.

The groups have said if the Cumberland replacement plant is allowed to proceed, it will emit an estimated 2.8 million tons of greenhouse gases annually. They also said TVA didn’t consider the cost of mitigating air pollution from the plant in its analyses.

Appalachian Voices’ Brianna Knisley said TVA struck “an early deal with an international corporation and then produced a faulty study of alternatives that was designed to favor that backroom agreement.”

When TVA retires Cumberland’s second coal-burning unit by the end of 2028, it may supplant the output with a separate, 900-MW gas plant in Cheatham County, Tenn., and a 400-MW battery storage system.

TVA insists it “has not yet made any decisions about replacement generation for the second unit at Cumberland Fossil Plant,” according to Gibson.

However, TVA has filed a notice of intent to prepare an environmental impact statement for the smaller, gas-fired plant.