How U.S. Utilities Could Double Their Electric Transmission Capacity by 2035

U.S. utilities could double their electricity transmission capacity by 2035 by replacing existing transmission lines with those made from advanced materials, according to a new study published today in the Proceedings of the National Academy of Sciences.

Led by Duncan Callaway, professor and chair of the Energy and Resources Group (ERG), and Amol Phadke, affiliate and senior scientist at the Goldman School of Public Policy, this first-of-its-kind study details a faster, more cost-effective way to expand the grid and connect the more than 1,200 gigawatts of renewable energy projects awaiting approval.

The analysis was first published last December as a working paper by Haas’ Energy Institute and has been covered by The New York Times, The Washington Post, Heatmap News and other media outlets.

“Increasing transmission capacity is critical to decarbonization, and we have sought to explore ways to develop it more quickly and at lower cost,” Callaway said.

It currently takes 10 to 15 years to build a new power line, and the United States is building transmission lines at a slower pace than it has in the past decade. Without enough capacity, renewable energy projects often sit on hold for years while transmission operators consider what, if any, improvements they can make to accommodate increased loads.

The authors modeled various scenarios to determine whether replacing existing transmission conductors with ones made with advanced composite core materials – a process known as reconducting – could pave the way for faster grid expansion.

Several re-conductor projects have been launched in Belgium and the Netherlands, and utility companies in the United States have used the material to install transmission lines over long distances, such as river crossings. However, the technology has not yet been used on the majority of overhead power lines that supply residential and commercial customers.

“As we learned more about the technology, we realized that no one had done the detailed modeling needed to understand the technology’s potential to increase transmission capacity at scale,” Phadke said.

According to the authors’ projections, it is cheaper and faster for utilities to replace the 53,000 existing transmission lines with advanced composite materials than to build entirely new transmission lines. They say this would reduce wholesale electricity costs by an average of 3 to 4 percent, resulting in savings of $85 billion by 2035 and $180 billion by 2050.

“The level of interest we have received from federal and state agencies, transmission companies and utilities is extremely encouraging, and since our initial report, the Department of Energy has committed hundreds of millions of dollars to renewal projects.

“We look forward to learning more about these projects as they develop,” said co-author Emilia Chojkiewicz, an ERG doctoral student affiliated with the Goldman School of Public Policy.

Additional co-authors include Nikit Abhyankar and Umed Paliwal, affiliated with the Goldman School of Public Policy, and Casey Baker and Ric O’Connell of GridLab, a nonprofit organization that provides comprehensive grid technical expertise to policymakers and advocates.