NASHVILLE (AP) — The nation's largest public utility is moving ahead with a plan for a new natural gas plant in Tennessee despite warnings that its environmental review of the project doesn't comply with federal law. The Tennessee Valley Authority announced in April that it would replace the aging coal-burning Kingston Fossil Plant with gas amid growing calls for the agency's new board of directors to invest in renewables.

The board, with six of nine members appointed by President Biden, is expected to meet on Thursday in Nashville, a day after a planned protest by a coalition of environmental groups demanding the utility stop investing in fossil fuels.

Decommissioning the Kingston plant, the site of a massive 2008 coal ash spill, is part of TVA's overall plan to reduce its reliance on coal. In analyzing alternatives to replace the plant, the utility considered either a new 1,500-megawatt gas plant or 1,500 megawatts of solar combined with 2,200 megawatts of battery storage. TVA concluded that a 2027 deadline for retiring the current plant does not give it enough time to develop the renewables alternative.

The Environmental Protection Agency asked the utility in a March 25 letter to redo several aspects of its analysis, citing "numerous" concerns with the plan to install new gas turbines. Among other things, the EPA accused the utility of defining the Kingston project so narrowly that only its predetermined choice of a new gas plant would meet the parameters, making the evaluation process a "foreordained formality." EPA said the utility did not adequately explain the need for the 2027 closure or look at possible alternatives.

The EPA said the environmental review does not meet the requirements of the National Environmental Policy Act, which requires federal agencies like the Tennessee Valley Authority to assess the environmental impact of proposed actions before making a decision.

TVA declined to follow the Environmental Protection Agency's suggestion for a do-over. It decided in April to forge ahead with gas — continuing to follow a plan of action that the EPA says fails to consider recent changes in the energy sector, including falling prices for renewables, billions of federal dollars for clean energy projects, and ever stricter environmental regulations. The corporation remains off track to meet the Biden administration's goal of eliminating carbon pollution from power plants by 2035 to try to limit the effects of climate change.

The utility said in a statement that "we met with EPA following the letter and addressed their concerns." EPA, meanwhile, maintained in an email to The Associated Press that its request that TVA revise its environmental impact statement still stands.

Dennis Wamsted, an energy analyst at the Institute for Energy Economics and Financial Analysis, said even with TVA's 2027 deadline, "They could build twice the amount of solar that they say they need and twice the amount of battery storage they say they need."

Other utilities are taking advantage of price drops, technical improvements and government incentives to build out solar, including in Texas and Florida.

By 2030, Florida Power and Light expects solar to account for close to 40% of its generation, Wamsted said.

"This is a big utility with, you know, the same daily responsibilities as TVA," he said. "And they are building out solar as fast as they can."

TVA provides power to 10 million people across seven Southern states. Florida Power and Light serves over 12 million people in that state.

Even if solar doesn't produce power 24 hours per day, the amount of energy it does produce is knowable and can be planned for, Wamsted said. It can also be paired with batteries that store excess energy during the day to release back to the grid at night. That is already happening on a large scale in California where batteries are providing more than 20% of the power in the system on many evenings, he said.

In Wamsted's view, many utilities resist the transition to renewables primarily because they are unfamiliar.

He points to an area called the Southwest Power Pool that runs from Oklahoma to Canada and now sees days where 60% or 70% of the system is wind-powered. In the late 2000s, he spoke to grid operators there who were afraid to go above 5% or 10% because they had never done it before, he said.

TVA's Kingston project is not its first clash with the EPA over gas. The environmental regulator made many of the same criticisms a year ago when the utility decided to build a new 1,450-megawatt natural gas plant at its coal-burning Cumberland Fossil Plant. The Sierra Club and other groups are suing over that decision as well as an earlier one to install gas turbines at a retired coal plant in New Johnsonville. Both lawsuits claim that TVA's environmental reviews are perfunctory, in violation of the law — similar to the EPA's criticism of the Kingston plant.

Democratic Sen. Ed Markey, of Massachusetts, a frequent TVA critic, said in a statement to The Associated Press that the corporation should listen to the EPA.

"The National Environmental Policy Act isn't optional — it's the bedrock of our environmental protection and community engagement laws," he said.

Although TVA has not embraced renewables, the utility still says a majority of its energy is carbon-free because 42% comes from nuclear and another 9% is from hydropower. Purchased wind and solar make up another 4% of its energy portfolio. The utility currently produces 1 megawatt of its own solar and has 20 megawatts of battery storage. The Kingston project includes another 3-4 megawatts of solar and 100 megawatts of battery storage. TVA estimates that the new gas plant will produce 1.68 million tons (1.52 million metric tons) of greenhouse gases a year, noting that that is a steep decline from Kingston's current emissions.

Nationally, coal provided about 16% of U.S. electricity last year, down from about 45% in 2010. Natural gas provides about 43% of U.S. electricity, with the remainder from nuclear energy and renewables such as wind, solar and hydropower.

The Tennessee Valley Authority has said it intends to build 10,000 megawatts of solar by 2035. Wamsted contends that is too far in the future.

"It should be, 'We're going to build as much solar as we possibly can now,' because it's now that we really need to worry about," he said. "We don't need to worry about 10 years from now or 15 years from now."

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Associated Press writer Jonathan Mattise contributed to this report.