Reconductoring transmission lines could be one solution to the growing demands on the grid
Energize Weekly, April 17, 2024
Faced with a soaring demand for transmission capacity in the U.S. and a dwindling number of new transmission projects, one strategy could be to upgrade the existing transmission network to carry two to three times as much electricity, according to a new study.
The technique – known as reconductoring – could double the capacity of an existing transmission line and take a fraction of the time to install than it takes to build a new line.
“A comprehensive approach to reconductoring transmission lines with higher performance wires, here referred to as advanced conductors, could rapidly increase transmission capacity at a low cost,” according to the study by the University of California Berkeley and GridLab, a clean energy consulting group.
After 15 years of stagnation – with little growth in electricity demand or in the grid – the combination of shifting generation (as coal-fired plants close and renewable generation is added) and soaring demand from the electrification of the economy are taxing the grid.
In 2022, total transmission congestion costs were estimated to exceed $20 billion nationwide, a 58 percent increase from 2021 as transmission expansion was unable to keep up with the growth of low-cost clean energy.
Extreme weather events such as Winter Storm Uri and Winter Storm Elliott, which led to blackouts in Texas and stressed neighboring states, also underscored the need for greater interregional transmission capacity across the U.S. to improve power system resilience, according to industry consultant Grid Strategies.
The National Transmission Needs Study, done by the U.S. Department of Energy, estimated that to rapidly electrify the U.S. economy and decarbonize the grid, intraregional transmission must double, and interregional transmission capacity must increase by a factor of six by 2040.
Reconductoring on a wide scale, with advanced conductors, could help quadruple the projected transmission capacity added by 2035, the study said, unlocking a 90 percent clean electricity system and saving $85 billion in energy system costs.
The technique replaces traditional lines – a steel-reenforced core surrounded by strands of electricity-conducting aluminum – with a line with a composite core, usually ceramic, glass or carbon fiber.
The lighter core enables adding more of the aluminum conductor – not strands, but more flexible annealed aluminum – to the line.
Though advanced conductors are an established technology – commonly used in Europe – the U.S. utility industry has not adopted it on a wide scale.
“Despite advantages like better efficiency, higher capacity, and improved reliability and resilience, the higher up-front cost of advanced conductors makes it difficult for utilities to justify wide, proactive use under current regulatory practice,” the study said.
The advanced conductors are about two to three times the cost of conventional conductors, the study said. Still, a reconductored line is 50 to 75 percent cheaper than building a new line.
The study found that a reconductoring project can be done in 18 to 36 months – three to five times faster than most new transmission projects – and at a lower cost.
The build rate for new transmission development dropped by more than half through the 2010s. In 2022, the U.S. transmission build rate declined by 50 percent year-over-year, to the fewest miles constructed in a decade.
Difficulties in siting, permitting, and financing have all been challenges for developing new transmission lines.
“Reconductoring is not a panacea — it does not reduce the urgency of fixing a broken permitting and cost allocation system for new transmission, and advanced conductors face important limitations in some circumstances,” the report said.
