The Southern Renewable Energy Association (SREA) said Thursday that the Duke Energy Carolinas and the Tennessee Valley Authority Christmas Eve blackouts were likely avoidable had they built more robust transmission links and had better access to organized wholesale markets.

SREA Executive Director Simon Mahan | SREA

SREA Executive Director Simon Mahan said during a briefing focused on the Southeast region’s performance issues and rotating blackouts during the December winter storm that the region contains a “balkanized, separated grid” where each utility must balance their own system without a shared resource pool to fall back on. (See FERC, NERC Set Probe on Xmas Storm Blackouts.)

“With better connections with our neighbors, we can avoid blackouts,” he said.

The load shed was a first for both TVA and Duke.

Mahan drew parallels between the recent winter storm and the more severe storm in February 2021. He predicted the Southeast will receive much of the attention for its performance in December because it’s isolated from a regional grid, as was — and still is — ERCOT two years ago. TVA and Duke need to build better transmission to prevent future outages and grid-scale failures, Mahan said.

TVA and Duke Energy both had major power outages about the same time on Dec. 24, Mahan said. He added that both imported significant amounts of power from organized wholesale markets to avoid a more dire situation.

Duke reached its highest emergency level and initiated rolling outages that same day. Mahan noted North Carolina’s northeastern corner remained stable because it is in the PJM footprint.

“While much of the state was under rolling blackouts, that corner of the state was not experiencing blackouts,” he said.

TVA at times imported more than 5 GW from MISO on Dec. 23 and 24, Mahan said. Those exports helped trigger the RTO’s own maximum generation event, setting off stakeholder debate on how far it should stretch its system to assist neighbors. (See MISO Actions During December Storm Spark Debate.)

According to the North Carolina Utilities Commission (NCUC), Duke was negatively impacting the entire Eastern Interconnection’s frequency on Dec. 24. Mahan said Duke was close to setting off “significant and widespread” outages like the 2003 Northeastern blackouts.

“The situation was really quite dire before they decided to start causing the rolling blackouts,” Mahan said.

Duke Carolinas under-forecasted demand by as much as 1.5 GW on Dec. 24, while Duke Energy Progress East had an even larger forecast gap at 2.8 GW, Mahan said.

The bitter cold proved “really difficult for the company to come back from,” he said, noting that Duke was not able to resume normal operations until nearly midday Dec. 26. Had it not been for solar generation’s strong performance on Dec. 24, Mahan said, Duke would have been thrown further into “dire straits.”

He said after analyzing preliminary import and export data from the Energy Information Administration, the Southeast region’s system may have been “so taxed and so overburdened” that loop flows materialized.

Mahan said state regulators should investigate the event and make findings public. “We need to get a better sense of what actually happened,” he said.  

Mahan said the region had indications that its grid and thermal generation would struggle during the storm. He said the wave of intense cold Dec. 23-24 fulfilled predictions meteorologists forecasted a week earlier.

“We should have been more prepared. We’ve seen it before. It’s happened before,” he said.

Mahan said the main difference between the two recent winter storms is that the December event had a “more direct bullseye” on the Southeast. He said he hoped more attention is paid this time to actionable changes.

Mahan said the Southeast needs more regional and interregional transmission connections; it’s imperative, he said, that Duke and TVA also diversify their generation mixes by adding more wind, solar and battery storage than natural gas plants.

Duke and TVA would have benefitted from larger solar fleets in this instance because sunshine was surprisingly plentiful during the event, Mahan said. He said as fossil plants struggled to be available on Christmas Eve, more solar generation would have shortened the length of the blackouts or made the outages less severe.

Chris Carmody, executive director of the Carolinas Clean Energy Business Association, said Duke would be better served if it “connects with a pack of states next door who don’t have blackouts.”

Duke Energy Carolinas CEO Julie Janson appeared before the NCUC Jan. 3 to apologize and vow the utility would learn from the experience.

“We own what happened,” she said. “We have set out on a path to ensure that if we are faced with similar challenges, we will see a different outcome and provide a better customer experience.”

Duke spokesperson Jeff Brooks told RTO Insider that the company “employed thousands of megawatts” during the storm. He said solar was added when it became available, but that it “was not generating at the time temporary outages were required as the sun was not up.”

Brooks said resources that Duke was counting on “included deliveries of generation from independent power producers and purchases through our out-of-state interconnections that were not fulfilled for use on Dec. 24 due to other utilities experiencing the same challenges.”

He said RTO membership “would present more risks than benefits to our customers and our state.” 

TVA has launched an internal investigation of its actions and has also pulled together an independent, three-person panel to separately review how it can better prepare for severe weather. The panel includes American Public Power Association President Joy Ditto; Mike Howard, former CEO of the Electric Power Research Institute; and former U.S. Sen. Bob Corker (R-Tenn.).

“This is not the way we want to serve our communities and customers,” TVA said in a press release late last month.

TVA said it had nothing more to add when RTO Insider requested a reaction to SREA’s recommendations.

Mahan said the Southeastern Energy Exchange Market (SEEM) didn’t appear to assuage the situation like an RTO could have.

“There should have been more willing purchasers on Dec. 23, but the market showed that it had even less purchases from the day before,” he said.

In fact, Mahan said that SEEM’s records showed no voluntary trades of excess power Dec. 24-26. He said that was “highly unusual,” but that it’s difficult to get a sense of what happened because SEEM isn’t a transparent operation.

“It wasn’t helpful at all for many days, which was very unfortunate,” Mahan said.

“It’s designed to do so little in the first place. There’s just not much to it,” Carmody said of SEEM’s structure.