Last summer, utility Duke Energy joined U.S. and state officials to announce with fanfare that it would rebuild a 40-mile transmission line between hurricane-prone Goldsboro and Raleigh, North Carolina. The company said the new infrastructure would result in fewer power outages, more solar connected to the grid, and hundreds of new jobs.
Funded jointly by the federal government and Duke, the project highlighted how advanced technology can help solve the problems posed by an aging electric grid: It will include cables better able to withstand extreme weather and modern support structures that can accommodate new sources of power.
“The grant announced today by the Department of Energy is a win for the communities Duke Energy serves, and signals North Carolina’s leadership in the energy transition,” Kendal Bowman, president of the utility’s North Carolina operations, said at the time.
But advocates and experts say the Lee-Milburnie transmission line in Eastern North Carolina is just the tip of the iceberg. To save consumers money and meet growing energy demand, they believe policymakers should follow other states’ lead and encourage Duke to perform many more grid upgrades like the one unveiled last summer.
Bipartisan legislation that would do just that failed to meet a key deadline last week, but its contents could still end up in another bill before the session ends later this year. Backers of the measure remain hopeful, in part because it would benefit all energy sources, not just renewable ones.
“It’s not a clean energy bill,” said Mel Mackin, state policy director for the nonprofit advocacy group Ceres. “It’s a grid-modernization bill. It’s about upgrading transmission lines to improve efficiency, to improve reliability. It’s about reducing grid congestion. We’re hopeful legislators will see it that way.”
A congested electricity highway
In North Carolina, as across the country, the transmission grid — the network of high-voltage lines designed to transport electrons across long distances — faces a confluence of challenges. For one thing, the grid is old: about 70% of today’s transmission lines were installed at least 35 years ago.
These aging conductors have much less capacity than newer ones, said North Carolina-based Maureen Quinlan, senior officer for energy modernization at The Pew Charitable Trusts. Old lines are also susceptible to failure from normal wear and tear as well as from extreme weather events like hurricanes and heat waves, causing “road closures” on the electricity highway.
“An element of the grid may go out, and you have to reroute the power,” Quinlan explained. “Detours are always going to be slower; you’re on smaller roads. That’s going to create inefficiencies.”
The resulting grid congestion from existing, interconnected power suppliers is one “today problem,” said Quinlan. A study from the consulting firm Grid Strategies estimated these bottlenecks cost consumers some $11.5 billion nationwide in 2023 because they force utilities looking to avoid congested areas to dispatch more expensive electricity than they otherwise would.
A second challenge for the present is the long line of projects waiting to merge onto the clogged highway that is the transmission grid. In North Carolina and throughout the Southeast, that “interconnection queue” is dominated by solar farms and battery storage.
As Duke and other utilities race to build power plants of all kinds to supply large data centers, manufacturing plants, electric vehicles, and more, the queue is poised to lengthen until the road is widened — that is, until the grid’s capacity is expanded.
“You already have a system that’s experiencing a lot of these constraints and backlogs,” said Quinlan. “That’s going to be compounded by growing energy demand.”
Addressing today’s bottlenecks helps utilities save money to address a hurdle for tomorrow: building brand new highways to bring large sources of energy, such as offshore wind, to population centers, such as the Raleigh-Durham-Chapel Hill area known as The Triangle.
That’s why experts are increasingly looking to advanced transmission technologies, which can quickly be added to the existing grid to allow it to carry more power.
“They can be deployed in a matter of months to a few years,” said Quinlan, “and they’re also very cost-effective. [Some] can pay for themselves in less than six months, so they’re seen as a bridge to these bigger transmission grid-level needs.”
The technologies include both hardware and software. Carbon composite conductors, for instance, are up to twice as efficient as traditional aluminum cables reinforced with steel, in part because they sag less when overheated. These modern lines are a key reason the Lee-Milburnie upgrade is expected to reduce the length of service interruptions by 10%.
