Powering Strong Communities

TVA Details Efforts to Bolster Grid in Preparation for Cold Weather

The Tennessee Valley Authority recently provided details on the most comprehensive cold-weather preparedness overhaul in TVA’s 90-year history — a to-do list of nearly 3,400 items that began earlier this year with the addition of more stringent winterization standards.

The work will be completed over the next few weeks, TVA said on Dec. 13.

TVA has invested nearly $123 million in the last three months alone to harden its system and enhance the reliability and resiliency at its coal, gas and hydro plants.

For Fiscal Year 2024, TVA is committing an additional $120 million above normal funding levels to focus specifically on enhancing the reliability of the generation fleet.  

Heat Trace System

At TVA’s Kingston Fossil Plant in Harriman, Tennessee, lights glowing on panels control the heat trace system, which protects outdoor pipes from freezing. Some of those lights – the green ones – have been around for years, indicating that the system is powered up.

But these past few months, TVA team members have installed additional lights – red ones the size of a hamburger.

“It looks like a Christmas tree,” Jason Forsgren, the winterization coordinator at Kingston, said.

Each heat trace light indicates power is flowing all the way to the end of an individual heat trace line.

The new monitoring system lets Forsgren tell -- even from his truck before dawn -- that the freeze protection system is operating correctly.

Heat trace is a thin, flat rubber cable containing conductive wires that heat up when electricity passes through them. It’s strung alongside pipes and sensitive instruments to help keep them from freezing.

At Kingston alone, TVA has replaced more than 2,000 feet of heat trace -- 45 individual lines -- along with the insulation that surrounds it.

Heat trace lines at all of TVA’s 17 gas plants and four coal plants have been modernized, accounting for more than 2,600 repairs. The new monitoring lights at some plants are blue rather than red, but they function the same.

TVA has also installed 443 wind breaks and enclosures to protect equipment from cold air. These include everything from heated shelters to tentlike temporary enclosures and heavy plastic butcher curtains like you might see in a walk-in cooler.

Another 339 preventive maintenance tasks have been carried out. These have focused on servicing heaters, staging auxiliary heaters and other emergency response equipment, and installing far more robust desiccant drying systems to protect critical air flow pipes and valves.

“We’re doubling our efforts to remove the moisture from the air,” said Derrick Shaw, a combustion turbine technician at Gallatin Combustion Turbine Plant in Sumner County, Tennessee. “If the air is dry, it will not freeze in temperatures typically experienced in extreme winter weather.”

67-Point Checklist

Each of these repairs and upgrades has been tracked using a system of dashboards. A person responsible and a deadline have been assigned for each one. There have been status update meetings multiple times per week.

Almost all the repairs are already done.

The final items being handled are at Ackerman Combined Cycle Plant in Ackerman, Mississippi, which has been in a planned maintenance outage.

A crew of TVA inspectors recently began fanning out to sites around the Valley region – armed with a multipage, 67-point assessment checklist – to sign off on the work.

Those inspections are expected to be complete by the first week in January, Norm Flake, TVA’s senior program manager of seasonal readiness, said.

TVA team members designed the inspection system to verify details, such as whether a seam on the lagging -- insulation surrounding the heat trace -- is positioned in a way that water could seep in and freeze.

On a plant-by-plant basis, the assessments will pin down critical details, TVA said.

The cold-weather to-do list was compiled earlier this year in “a top-to-bottom, fully detailed assessment of every single one of our systems and plants across our coal and gas fleet,” Allen Clare, TVA vice president for power operations performance improvement, said.

TVA’s winter readiness overhaul has also included updated cold-weather response plans, training and drills, and a more rigorous approach to regular maintenance.

These process improvements will pay dividends far beyond the current winter, Clare said.

Every time equipment is disassembled and reassembled for regular maintenance, it will be checked for even seemingly minor items, such as the insulation seam placement.

“Every year, our plants conduct planned outages, which requires disassembling and reassembling equipment,” Clare said. “Freeze protection is a complex system and, if not properly reassembled, it will not function effectively.

“Proper attention has to be paid to all of these minute details during maintenance activities. We’ve revised our processes and programs and made them more robust.”

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