As grid operators across the United States plan new transmission lines to keep up with surging investment in renewable energy, electric vehicles and heat pumps, many are neglecting an easier solution: stringing a new set of wires their existing lines. In fact, such ‘reconductoring’ could provide the bulk of the extra transmission capacity the United States will need through 2035, according to grid modeling research published this weekin the Proceedings of the National Academy of Sciences (PNAS).
“If we go all-in on reconductoring now it can meet a very significant portion of our transmission needs,” says lead author Emilia Chojkiewicz, an energy and resources doctoral student at the University of California, Berkeley.
Grid operators are in a race to revamp their grids as climate change drives extreme weather that’s straining their systems. Some grid operators are mapping out dozens of new lines, and state and federal regulators are trying to shorten line construction times from an average of 10 years to as little as 5. But Chojkiewicz says it’s not enough: “Even if we start planning today, that’s still looking at the early 2030s, and I don’t know if we have that kind of time.”
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What U.S. operators are missing, according to the PNAS report, is the net savings that advanced conductors offer. 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.
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[T]aking out lines that are heavily loaded is tough because the grid is hard-pressed to operate without them. Workarounds exist: Where multiple circuits share the same right-of-way, utilities can replace one circuit at a time during a low-demand season, especially when maintenance is already scheduled (see photo above). That’s how Belgian utility Elia is replacing all of its big trunk lines with ACCC.
The authors of the PNAS paper cite a more daring approach employed in Texas over a decade ago: swapping out wires for a single-circuit while it remained energized. In that case, lines in southeastern Texas had maxed out, leading to rolling blackouts during a severe ice storm in February 2011. To boost capacity quickly, the operator transferred the live wires to temporary poles as it installed the ACCC wires.
From the article:
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