TVA announces new natural gas plant to replace Cumberland coal plant

The Tennessee Valley Authority will replace its Cumberland coal plant with a natural gas facility, the federal utility announced Tuesday, over the objections of environmental groups.

The switch to natural gas will require the construction of a new 32-mile natural gas pipeline across Dickson and Houston counties, crossing over to the plant in Stewart County.

The Cumberland City plant is TVA’s largest generator of electricity, powering 1.1 million homes. It consists of two coal-fired units: the first unit will be retired and replaced with a 1,450-megawatt combined cycle natural gas plant by 2026. The second unit will be retired by 2028. TVA has not yet determined how it will replace the second unit.

Tuesday's announcement came about two weeks after a severe winter storm in which some of TVA’s coal and natural gas plants, including Cumberland, succumbed to cold weather, forcing the utility to implement rolling blackouts for the first time in its history.

TVA tends to run Cumberland 24/7 because the plant generates a large amount of electricity and because it is easier to keep it running than to turn it on and off like a natural gas plant. However, when Cumberland effectively went dark in late December, on the coldest days of the year, TVA scrambled to find replacement electricity, demonstrating the utility's reliance on that plant's generation and the need to replace it with something just as powerful but more resilient.

In response to concerns about the failure of some natural gas plants in December, TVA CEO Jeff Lyash said the natural gas plant TVA plans to build at the Cumberland site will be more resilient than the ones that failed during December’s winter storm.

The announcement followed a nearly-two-year environmental review process in which environmental groups, the U.S. Department of Interior and the Eniveronmental Protection Agency criticized TVA for not meaningfully exploring other options, such as renewables like solar, to replace the coal plant instead of choosing another fossil fuel.

The transition from coal to natural gas will cut carbon emissions from the facility by up to 60%, TVA said. TVA plans to have net zero carbon emissions by 2050, and one of its biggest moves toward that goal is retiring all five of its current, aging coal plants by 2035.

While coal is much dirtier than gas in terms of how much carbon dioxide and other air pollutants it produces, gas is composed primarily of methane, a more potent greenhouse gas.

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The supply chain that leads up to the gas plant has been known to intentionally and unintentionally release large quantities of gas, offsetting some of the carbon reductions the switch from coal to gas could have. Companies along the supply chain and regulatory agencies are in the process of reducing those emissions and making the supply chain safer, but it's still questionable how effective those changes are and will be.

Regardless, Lyash said on Tuesday that only natural gas can provide the reliable power needed to replace coal at the site. While renewables can provide intermittent energy to the grid, combined cycle natural gas plants can provide larger amounts of energy normally when TVA needs them to run.

Combined cycle plants burn gas that turns turbines, and the heat generated from that process is taken and put with water to generate steam, which turns a steam turbine, increasing the amount of power generation in one plant. Those plants can be turned on and off, but TVA tends to run them continuously because of how much energy they generate. TVA has eight of these plants, primarily located in the western part of its seven-state region.

“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,” Lyash said.

Still, environmental groups condemn the plan to replace coal with another carbon-emitting fossil fuel.

“Just a few weeks after failing fossil fuel plants caused rolling blackouts across its footprint, the Tennessee Valley Authority is recklessly plowing ahead with plans to spend billions on another dirty gas power plant,” said Amanda Garcia director of the Southern Environmental Law Center’s Tennessee Office, on Tuesday in an emailed statement. “Instead of doubling down on fossil fuels, TVA must invest in clean energy sources that can reliably provide cleaner and cheaper power.”

TVA is moving forward with its plan despite the federal Environmental Protection agency declaring last week that it had “substantial” concerns about TVA’s final Environmental Impact Statement related to the Cumberland site.

Federal law requires TVA to evaluate the environmental impact of shutting down a facility like Cumberland, and evaluate possible replacements. The EPA found that TVA failed to properly evaluate alternatives like solar at the site, noting that “the alternatives analysis continues to rely on inaccurate underlying economic information.”

Specifically, TVA failed to account for expected declines in the cost of clean energy and increases in the cost of natural gas, EPA said.

TVA’s choice to replace coal generation with natural gas failed to address the “implications of continued fossil fuel investment of its ratepayers and the cost and public health toll of increasingly disruptive climate-driven weather extremes,” the EPA wrote.

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In an interview Tuesday, Lyash said the TVA had worked to address the EPA’s comments. He also pointed out that the environmental review process was limited to the Cumberland site, and failed to address changes TVA was making across its system.

“Many people want to look at the EIS and ignore that over here we’re building 10,000s of megawatts of solar and over there we’re issuing a 5,000 megawatt clean energy RFP,” Lyash said.

The natural gas plant at the Cumberland site will be able to run on hydrogen fuel, or a mix of hydrogen and natural gas, if that technology becomes viable in the coming years. Likewise, the plants will be built so that carbon capture technology can integrated into the system if that technology matures and becomes cost-effective, Lyash said. Both of these technologies could help reduce TVA's carbon footprint even further but many questions remain as to the viability of such technology and when it will be ready.

Anila Yoganathan is a Knox News investigative reporter. You can contact her at anila.yoganathan@knoxnews.com, and follow her on Twitter @anilayoganathan. Enjoy exclusive content and premium perks while supporting strong local journalism by subscribing at knoxnews.com/subscribe.

This article originally appeared on Knoxville News Sentinel: TVA announces new natural gas plant to replace Cumberland coal plant