A new climate change preparedness study has found that the greatest risks to Duke Energy's electrical transmission and distribution system by 2050 will be extreme heat and flooding, mainly at substations.
Duke Energy worked with consulting firm ICF over the past two years to develop the "Climate Resilience and Adaptation Report," which was required by state regulators. It's separate from Duke's Carbon Plan, which addresses the transition away from fossil fuels for generating electricity. This report examines the electric grid's vulnerabilities to climate change — heat, cold, flooding, wind and wildfire — for both moderate and worst-case scenarios for global warming over the next few decades.
"What the study is going to allow us to do is better inform future grid resilience improvements, you know, to make our system more resistant to outages and disruptions from climate-related events," said Cynthia Klein, Duke's director of strategic initiatives.
About 5% of Duke's 1,200 substations in the Carolinas are in floodplains, which means they'll be increasingly susceptible as climate change brings more intense storms. Many have been affected by hurricanes in recent years, and Klein said Duke already has started addressing those kinds of risks.
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"We implemented permanent flood mitigation at the 14 substations that actually experienced flooding during Hurricane(s) Matthew and Florence," Klein said. "We've increased our design standard elevation for new substations, and we also deploy temporary flood mitigation measures ahead of storms for substations that are in the path of the storm."
Other risks to the grid
The report also estimates that by 2050 up to 80% of Duke's transmission lines could be at risk from temperatures hotter than they were designed for. The report says transmission planners typically use 104 degrees as the standard, which determines how much power can be sent over the lines. As temperatures rise beyond that, operators will have to reduce the amount of power transmitted. That means Duke will need to find ways to reduce demand, add equipment to increase capacity, or install new transmission lines.
And the report recommends that Duke improve how it plans, monitors and maintains aging plants and equipment to account for climate-driven extreme temperatures and flooding. Age and maintenance were key issues last December when single-digit temperatures froze equipment at several gas and coal plants, forcing rolling blackouts across North Carolina.
Nick Jimenez, a lawyer with the Southern Environmental Law Center, said he welcomes the more detailed discussion of climate risks. But he worries that it doesn't pay enough attention to how distributed energy — like rooftop solar or local microgrids — could address climate risks among the most vulnerable populations.
"For people who are particularly vulnerable to power outages, whether low income, maybe dependent on a medical device, or something that needs power to keep running, elderly vulnerable to heat stress … there is a value to more local distributed resources and more localized resilience," Jimenez said.
Jimenez said he's curious whether Duke and regulators will act on the plan. But Tommy Williamson, of the North Carolina Utilities Commission public staff, the state's utility consumer advocate, says the report won't sit on the shelf.
"This is not going to be a one-and-done process. It's going to be continuing, I'd say, for years to come," Williamson said.
State regulators are expected to use the report as they evaluate Duke Energy's long-range grid plans, rate hikes and other requests.
