Retired Fossil Plant Eyed as Green Energy Asset

 When Tennessee Valley Authority workers finished Bull Run Fossil Plant in 1967, it stood proudly as the world’s largest in volume of steam produced.

On Dec. 1, 2023, after 56 years of operation, this storied generating asset near Oak Ridge, Tennessee, retired.

It’s the only single-unit plant in TVA’s coal fleet.

“Bull Run has provided electricity to more than 400,000 homes for more than 50 years,” Kris Edmondson, vice president of TVA Coal Operations, said. “The team at Bull Run has left a strong legacy in this community. The power they produced made significant impacts that should be remembered and honored.”

TVA originally built Bull Run to meet the energy needs of the thriving city of Knoxville and the rest of the Tennessee Valley region.

But even today, the plant’s location is important for TVA’s energy system of the future.

After Retirement

Once Bull Run Fossil Plant retired, TVA removed 765 megawatts of electricity from the grid.

Once the decommissioning process begins, elements of the site may be eligible for reuse. Some of the options include installing battery storage, pursuing economic development opportunities, exploring innovation, adding new generation or establishing a portion of the area to a green space for community use.

The future of this site will depend on a few factors – environmental reviews to determine the impact of each option, community feedback on the preferred best use, and a final decision by TVA.

It’s a thorough process to determine what’s best for the people of the Valley region.

In North America, the grid entails generating assets, a massive, complex network of transmission lines, and other electrical equipment. TVA’s Transmission team manages the grid within the seven-state TVA territory.

“As TVA evolves to a cleaner energy portfolio, including retiring and adding generation, we are working to meet demand with the right generation mix and investing over $2.8 billion in transmission improvements through 2027,” Nate Schweighart, general manager of Transmission Planning, said. “As we look at the next 10 to 15 years, we are focused on ensuring grid stability and keeping power flowing reliably through our transmission lines.”

The transmission system operates at a system frequency of 60 hertz, which is accomplished through matching generation output with energy consumption in real time. Spinning generation – rotating turbines that create power at TVA’s current generating facilities – is one of the ways to provide frequency stability as generation or consumption changes unexpectedly.

“Once we remove the spinning aspect by retiring a generating asset, we reduce the natural inertia maintaining the grid system frequency and decrease system support in that region,” Schweighart said. “And without careful planning, this could lead to instability.

“In addition, as we add renewable energy such as solar power, which doesn’t have a spinning element, we exacerbate the issue.”

Optimal Spin, Optimal Grid

TVA is considering a solution for this: a synchronous condenser.

Similar to a generator, a synchronous condenser spins. But unlike an operating plant, it doesn’t produce any real power. It simply operates to support the transmission grid.

“Our older fossil plants are perfect for this solution,” Schweighart said. “They already have the existing infrastructure, transmission lines, etc. And in Bull Run’s case, it’s located in a key strategic geographic location in the TVA service territory to provide grid stability in a largely populated area.”

While this is currently just an idea, TVA project manager Bob Rehberg is working to determine if the Bull Run site could indeed house a synchronous condenser.

“Right now, we are in the early stages of considering this option and have submitted a request for proposals to get quotes from contractors who specialize in this work,” Rehberg said. “We won’t make any decisions without community input and TVA Board approval.”

If the project is approved, Bull Run’s existing generator would be reconfigured. A limited crew would continue working at the site to maintain the synchronous condenser, which would be in the turbine building.

Most of the other buildings – scrubbers, coal handling and more – would be demolished as part of the retirement.

A Greener Future

As TVA moves away from traditional fossil generation and toward cleaner energy, its specialists will continue to have to find new ways to ensure the enterprise has a stable and reliable power system.

“If you add on that TVA is building up to 10,000 megawatts of solar generation by 2035, the need for a synchronous condenser will be even more critical,” Rehberg said.

As TVA’s energy portfolio evolves, synchronous condensers and other innovations will prove vital to optimizing the grid.

“We don’t want to miss the opportunity to support a clean energy future,” Schweighart said. “And with the dedication of this team, we won’t.”