Silvio Marcacci, writing for Forbes, noted in an April 2024 article that U.S. power transmission expansion was growing at 1% per year while experts were predicting that 4-7% expansion rates were needed to accommodate renewables and storage integration. Then, it was expected that growth would come from the Inflation Reduction Act, but project slowdowns and rollbacks have stifled that growth source. However, AI infrastructure and continuing electrification have and will continue to accelerate growth. The article noted that research from Energy Innovation, GridLab, and the University of California-Berkeley showed that reconductoring existing transmission lines with advanced conductors can double capacity on existing rights-of-way in just 18 to 36 months. The technology could potentially quadruple the transmission growth rate (presumably to 4%).
“Reconductoring is the utility industry term for
re-stringing existing transmission towers with new cables, without having to
permit and build expensive new transmission towers and power lines. Advanced
conductors are a modern, commercialized technology that use composite cores
instead of steel, making them stronger and lighter, and denser annealed
aluminum for conductors instead of aluminum strands, increasing capacity up to
2x.”
These upgrades are good
investments with the major advantage of no need for permitting.
The article gives three
barriers to the adoption of reconductoring in the U.S. The first is a perhaps
perverse incentive where utilities that earn a return on total investment can
earn more by building new grid projects than by reconductoring along the same
right-of-way as current lines. Advanced conductors are more expensive, so some
utilities may see them as an unnecessary expense. Secondly, utilities and
regulators may be unsure of future demand growth and see investments in
reconductoring as risky, even if there are known benefits, including better
efficiency, reduced emissions, easier integration of renewables and storage,
and better wildfire protection. Thirdly, a lack of experience with advanced
conductors by some utilities may lead them to take a cautious approach with
them, treating them as pilot projects with slower and lesser rollouts, despite
them being used around the world for the last two decades. The article suggests
that policy incentives could help advanced conductor rollout.
“The federal government and U.S. Congress should provide
funding support for grid modernization and expansion efforts, industry
collaboration, and training for utilities to work with advanced conductors,
beyond the funds allocated in the Inflation Reduction Act and Infrastructure
and Investment Jobs Act.”
They note that it may be difficult since in the Southeast
and West, where monopoly utilities control information about transmission
benefits, and suggest “independent transmission monitors to objectively
review investments.” States and state agencies can also help with education
and project approval.
A late September 2024 article
in IEEE Spectrum by Peter Fairley also explains the benefits of reconductoring.
Here, the authors also emphasize power demand growth from EVs and heat pumps,
not mentioning AI data centers. The article notes, citing the paper in the
Proceedings of the National Academy of Sciences (PNAS) by researchers at the
University of California, Berkeley, that the bulk of transmission expansion to
2035 could be along existing rights of way through reconductoring. Fairly’s
article is mainly a summary and review of the paper. Emilia Chojkiewicz, an
author of the paper, suggests we go all-in on reconductoring now. New
transmission line construction projects typically take a decade, although
regulators hope to cut that in half to 5 years.
“Most of the more than 800,000 circuit-kilometers of
transmission in the United States over 100 kilovolts use aluminum wires wrapped
around a steel core. Chojkiewicz and her colleagues at Berkeley’s Energy and
Resources Group and Goldman School of Public Policy studied the use of advanced
conductors that wrap more aluminum around a smaller, stronger composite core.
These Aluminum Conductor Composite Cores (ACCCs), made by CTC Global, are more
conductive and can operate at higher temperatures, resulting in roughly a
doubling of capacity for an equivalent diameter wire.”
These solutions are proven
and available now. On its website, CTC Global notes:
“CTC Global’s ACCC® Conductor has been successfully
installed at over 1,350 projects in 65+ countries by more than 300 utilities
for projects ranging from 11 kV distribution line upgrades to 345 kV energized
reconductoring projects to 1,100 kV new DC substations.”
The Wikipedia entry for ACCC
conductor explains some advantages and disadvantages of this type of advanced
conductor. The advantages include doubling the power-carrying capacity,
enhancing redundancy, and carrying more power at similar temperatures.
“Operation at high temperatures implies high line
losses, which may be uneconomical, but the ability to carry such current
contributes to the redundancy of the electric grid (the high overload capacity
can stop a potential cascading failure) and thus can be valuable even when
rarely used directly. Even at higher operating temperatures, the ACCC
conductor's added aluminum content and lower electrical resistance offers
reduced line losses compared to other conductors of the same diameter and
weight.”
The disadvantages of ACCC are
listed below. Cost is no doubt the biggest concern for utilities.
Explaining the conclusion of
the PNAS paper, Peter Fairley’s IEEE Spectrum article notes:
“The wires themselves can cost two to four times more
than steel-core wires. But a reconductoring project adds capacity at less than
half the cost of new lines by eliminating the land acquisition and permitting
costs. And the job can usually be completed in a year or two, rather than the
decade typically required to build a new transmission path in the United States.”
The paper’s authors used
modeling to determine the best choices between reconductoring, building new
lines, and adding more generation. Even with conservative estimations of the
cost of reconductoring, it still beats out new line builds based on the
modeling. However, the modeling was likely based on achieving the Bien
administration’s 90% clean power by 2035 push, which is no longer the likely
paradigm, especially for utilities. A slower, smarter buildout would be better,
although fast builds could be done where they are most needed or most
economical. A more feasible, slower buildout would require some reconfiguring
in the modeling, but I am guessing it should not change it too much. The
authors estimated significant potential savings of $85 billion over the long
term.
The paper's abstract and some of its figures are reproduced below.
Fairly praises the benefits
of reconductoring but also notes some challenges and misconceptions. Project
collaborator Grid Lab’s technical report has an appendix of technologies that
can increase capacity within existing rights-of-way, but Fairley notes that
cost, benefits, and feasibility comparisons between these technologies and
reconductoring were not addressed in the paper, the authors noting that they
were aiming to model a path for reconductoring. They also noted that all of the
methods would be needed to achieve the desired transmission expansion rates.
The paper’s frequent mention of getting beyond fossil fuels (in line with
Biden’s overly ambitious plan) suggests a possible bias among the authors,
although the Grid Lab report declares a non-partisan approach. According to
Fairley:
“The Berkeley team’s report provides no insight into how
reconductoring measures up against alternative strategies to send more power
through existing rights-of-way. Other such grid-enhancing technologies (GETs)
include boosting line voltage, adding converters so that a line can carry high
voltage direct current (HVDC), or installing sensors to indicate when favorable
winds and temperatures mitigate the risk that extra power will send overheated
lines sagging into the trees below.”
Several of those alternative strategies are actually complementary to reconductoring. One strategy, Dynamic Line Rating, is something that should be done on all congested power lines, notes Chojkiewicz. FERC made a rule in 2024 that required utilities to look into and model reconductoring for their projects. Chojkiewicz wants to see more government pushes to require the technology, but that does not seem likely at the federal level with the current administration. She wants to see a national conductor efficiency standard that operates like an energy conservation standard, like existing energy conservation standards for distribution transformers. Some figures from the Grid Lab technical report are shown below.
Conductor manufacturer TS
Conductor emphasizes its compatibility with current industry installation and
maintenance practices.
“AECC is the only advanced conductor that is fully
compatible with traditional ACSR/ACSS installation and maintenance practices.”
TS Conductor shows some of
its products’ beneficial features below.
Conductor manufacturer VEIR
touts its advanced high-voltage conductors for data center power lines as well
as overland transmission, offering much more power. One feature of its product
is:
“… a simple, open loop, passive
nitrogen cooling system where distributed evaporation delivers 20x the cooling
power per kilogram of liquid nitrogen coolant.”
“Our next-gen superconducting transmission lines
represent a major leap in energy infrastructure, delivering 5-10 times more
power than conventional lines at the same voltage level. These advanced lines
operate at much higher currents, with negligible energy losses compared to both
traditional and other advanced conductors.”
The company is also working
on solving bottlenecks in behind-the-meter apps for data centers and industry
at lower voltages.
References:
A
Faster, Cheaper Way to Double Power Line Capacity: Modeling shows that
reconductoring can quickly beef up grids. Peter Fairley. IEEE Spectrum.
September 25, 2024. Reconductoring:
Boosting U.S. Grid Capacity Efficiently - IEEE Spectrum
Reconductoring
Could Help Solve America’s Looming Grid Crisis. Energy Innovation: Policy and
Technology and Silvio Marcacci. Forbes. April 9, 2024. Reconductoring
Could Help Solve America’s Looming Grid Crisis
More
Capacity, Less CapEx. TS Conductor. Next-Generation
Advanced Conductors for Utilities | TS Conductor
Delivering
10X Power Density: Advanced Power Delivery Systems for Data Centers, Power
Generation, and Utilities. Veir. VEIR | Pioneering
Superconducting Power Line Solutions
Accelerating
transmission capacity expansion by using advanced conductors in existing
right-of-way. Emilia Chojkiewicz, Umed Paliwal, Nikit Abhyankar, Casey, Ric O’Connell,
Duncan Callaway, and Amol Phadke. Proceedings of the National Academy of
Sciences (PNAS). 121 (40) e2411207121. Accelerating
transmission capacity expansion by using advanced conductors in existing
right-of-way | PNAS
ACCC
conductor. Wikipedia. ACCC
conductor - Wikipedia
CTC
Global. Website. The
Advanced Conductor | CTC Global
Reconductoring
With Advanced Conductors Can Accelerate the Rapid Transmission Expansion
Required for a Clean Grid. 2035. The Report. April 2024. GridLab_2035-Reconductoring-Technical-Report.pdf
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