Duke Energy had problem with power source equipment pre-blackout, officials confirm
Before rolling blackouts across the Carolinas on Christmas Eve, some equipment that Duke Energy relies on to generate power for millions either stopped producing energy or produced less than expected, officials have confirmed.
In messages to customers and the public over the last week, Duke Energy officials have pointed to high electricity demand that placed “unusual strain on the energy grid” amid freezing temperatures.
But the utility now says that unresponsive generating units played a role in the power shortage that led the company to begin rolling outages on Dec. 24 with little notice to residents.
WRAL, in Raleigh, first reported the generator problems on Wednesday. Previously, as The Charlotte Observer reported Sunday, officials indicated equipment issues may have contributed to problems of supply and demand, while noting the need for rolling blackouts in the region were rare.
“The majority of our generating units performed as expected. But some units did not generate power or operated at reduced capacity in the pre-dawn hours on Christmas Eve,” spokesman Bill Norton told the Observer on Thursday.
“The power output was lower than we expected — we’re still evaluating why.”
Duke Energy, Norton added, “believed we had adequate resources available to meet customer demand going into the weekend, even though some generation was unavailable due to either planned or maintenance outages unrelated to the storm. Some additional generation was reduced overnight as a result of weather.”
The company was also counting on generation from independent power producers and out-of-state energy purchases that fell through as other providers were similarly slammed by extreme weather, Norton said.
The reduced output — along with higher-than-expected electricity usage and the inability to ship in new energy from neighboring power companies — pushed Duke Energy to roll out the rotating blackouts, Norton said.
The company’s acknowledgment of lower-than-expected generation corresponds with federal data showing a dip in natural gas and coal energy production on Saturday morning. The data, recorded hourly, is reported by individual utilities and collected by the U.S. Energy Information Administration.
State leaders and frustrated customers are looking for answers as to why Duke Energy, one of the largest energy companies in the U.S., found itself in trouble when severe winter weather struck the region last weekend.
Gov. Roy Cooper said Monday he was “deeply concerned” about those who lost power over the Christmas weekend without receiving notice from the utility ahead of time. On Twitter, Cooper said that he wanted Duke Energy to provide him “a complete report on what went wrong and for changes to be made.”
Duke Energy will also have to brief regulators on the outages at a meeting of the N.C. Utilities Commission on Tuesday.
Duke Energy rolling blackouts on Christmas Eve
Duke Energy announced in the early hours of Dec. 24 that it would institute rolling power outages in North and South Carolina.
That came as a surprise to customers, many of whom took to social media to complain of little to no notice from the utility before their own power went out.
The blackouts were supposed to last 15 to 30 minutes. But several customers told the Observer they were without power for longer, piling on sweaters and blankets in their homes during one of the coldest days that North Carolina has seen in decades.
“We had three layers of woolen clothes on, I was under two heavy duvets and my nose was still ice cold,” one Durham resident told the Observer. Her power went out at about 9 a.m. on Christmas Eve, when it was 10 degrees outside.
About 500,000 Duke Energy customers lost power during the blackouts.
Norton says the company knows the outages were “inconvenient and frustrating ... especially occurring during the holidays.”
On Thursday he said: “We will work to learn from this incident to continually improve our strategy and better serve customers now and in the future. We are also working to improve the electric grid to make it stronger to help avoid outages, as well as more resilient to serve customers in good weather and in bad.”
In an interview this week with WSOC, the Observer’s news partner, Duke Energy spokesman Jeff Brooks said: “We certainly understand that (lack of communication) was frustrating, and we apologize for that. We were moving very quickly in taking these measures.”
Power grid emergency
Utility companies like Duke Energy plan out a certain amount of generating capacity based on projected peaks in demand during summer and winter, said Robert Cox, an assistant professor in UNC Charlotte’s electrical engineering department.
But if that demand is higher than expected — or, for some reason, the company can’t generate enough power to meet it — rolling blackouts offer a way to shrink demand and prevent a bigger crisis.
Stopping power in certain communities prevents a broader failure of the power grid that could lead to a widespread, longer-term outage, Cox explained. Something similar happened in Texas last winter.
“If they’re reaching a point where they’re getting concerned, that’s when they feel they’re obligated to start rolling blackouts,” he explained. It’s a strategy that falls within regulatory guidelines, he added.
Even though Duke Energy attempted to account for increased energy usage during last weekend’s winter storm, demand exceeded its predictions, Norton said.
“We believed that we had adequate resources heading into the weekend to meet customer demand for electricity,” he said. “When you’re talking 4.5 million customers across the Carolinas, a cumulative increase in demand can add up quickly.”
UNCC electrical engineering professor Badrul Chowdhury added that Duke Energy works with neighboring power companies — like Dominion in Virginia and Atlanta-based Southern Company — to share power when necessary.
But it’s unlikely those other companies would have had much energy to spare on Saturday, he said, as arctic temperatures slammed the entire east coast.
“The entire eastern seaboard was probably under very heavy duress (with the winter weather),” Chowdhury said. “So nobody could actually send any extra power.”
What led to blackouts?
According to federal data from the Energy Information Administration, Duke Energy’s natural gas and coal energy generation dropped during the morning of Dec. 24.
Tyler Norris, a Raleigh-based executive at a solar power company, plotted the data for Duke’s combined entities in a graph he shared on Twitter. There’s still a lot we don’t know about what exactly happened that morning, he noted. But it’s unusual that energy generation from natural gas — one of Duke Energy’s primary fuels — would drop from nearly 10,000 to about 6,000 megawatt hours during the outages.
“It’s kind of perplexing. Those are substantial numbers,” said Norris, who worked for the U.S. Department of Energy under former President Barack Obama.
Cox suspects that because of freezing temperatures, some of Duke Energy’s equipment produced less power than expected throughout the morning, diminishing the supply of energy as demand hit its peak.
“My suspicion is that we’re going to find out that Duke was a little bit caught off guard,” Cox said. “Because some assets were having issues that they were surprised by.”
This story was originally published December 29, 2022 at 5:40 PM.
