TVA favors building gas plant to replace aging Kingston coal-fired units
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TVA favors building gas plant to replace aging Kingston coal-fired units

The Tennessee Valley Authority is expected to retire its nine-unit, coal-fired Kingston Fossil Plant by 2027 and replace it with a natural gas-fired plant, solar and battery storage.

That was the verdict from TVA’s Final Environmental Impact Statement issued by the federal utility Feb. 16 after a public review process last year over how to replace the coal-fired units at Kingston. TVA anticipates making a final decision in March 2024.

TVA mainly evaluated two options to provide at least 1,500 MW of generation to replace the capacity to be lost, plus additional capacity to support anticipated load growth.

The first option would include the construction of a single combined-cycle gas plant paired with 16 dual-fuel Aeroderivative combustion turbines, a 3 to 4 MW solar site and a 100 MW battery energy storage system on the Kingston Reservation. The combined-cycle plant would be capable of burning 5 percent hydrogen by volume at commissioning and 30 percent hydrogen with modifications to the balance of plant once a reliable source of H2 was identified, TVA said.

The first option would also include Eastern TN Natural Gas (ETNG) constructing and operating a 122-mile natural gas pipeline, gas compressor station and metering and regulator stations.

The second option would consist of constructing multiple solar and energy storage facilities at alternate locations, including in Eastern Tennessee. The construction of a pipeline would be subject to Federal Energy Regulatory Commission (FERC) jurisdiction and additional review.

TVA said its preferred option is the first. The federal utility said a combined-cycle plant paired with dual-fueled aero turbines would be the “best overall solution to provide low-cost, reliable energy to TVA’s power system, and could be built and become operational sooner” than the solar and storage in the second option.

The utility said it also preferred the gas plant option to provide the flexibility needed to bring 10,000 MW of solar onto the system by 2035.

‘Increased wear and tear’ for coal units

Kingston’s nine units can generate about 1.4 GW of electricity at capacity. The plant, located about 35 miles west of downtown Knoxville, entered operations in the 1950s.

TVA said frequent cycling of Kingston’s units, reflected in start-up and shutdown events, are currently averaging more than 85 times per year, which the utility said is outside the intended design of the plant.

This is resulting in “increased wear and tear, which presents reliability challenges that are difficult to anticipate and expensive to mitigate.”

TVA also said Kingston has experienced a “significant decline” in material condition over the last five years, including the need for repairs to the lower boiler drum, which the utility said are symptomatic of age-driven material condition failures which are difficult to proactively address.

The utility said based on these factors, it has developed planning assumptions for the timing of the proposed retirement of Kingston.

In general, TVA said its aging coal fleet is experiencing deterioration of material condition and performance challenges. Performance challenges are expected to increase because of the fleet’s advancing age and the difficulty of adapting coal within the changing generation profile.

TVA has reduced carbon emissions from its entire generating fleet by about 60% since 2005, thanks to a combination of closing coal plants and building solar and wind.

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