Ask any climate wonk what’s holding back clean energy in the U.S. and you’re likely to get the same answer —
not enough power lines. But what if the problem isn’t the number of power lines, but rather the outdated metal wires they’re made of?
Restringing transmission lines with more advanced wires, a process known as “reconductoring,” has the potential to double the amount of electricity our existing transmission system can handle, for less than half the price of building new lines. That’s the main finding of a recently published working paper from researchers at the University of California, Berkeley, and Gridlab, an energy consulting firm.
There are a few reasons that something as boring and seemingly ubiquitous as power lines are so crucial to the energy transition. Electrifying our cars and homes will increase demand for electricity, and much of the system is already too congested to integrate new wind and solar power plants. Plus, there just aren’t enough lines that run from the sunniest, windiest places to the places where most people actually live.
To realize the emission reduction potential of the clean energy subsidies in the Inflation Reduction Act, we have to
more than double the rate of transmission expansion, according to research from Princeton University’s Repeat Project. Clean energy projects already face major delays and are often hit with exorbitant bills to connect to the grid. A study from Lawrence Berkeley National Laboratory called “Queued Up” found that at the end of 2022, there were more than 10,000 power plant and energy storage projects waiting for permission to connect to the grid — enough to double electricity production in the country. Some 95% of them were zero-carbon resources.
The main problem is
permitting. Establishing rights-of-way for new power lines requires extensive environmental review and invites vicious local opposition. People don’t want to look at more wires strung across the landscape. They worry the eyesore will decrease their property value, or that the construction will hurt local ecosystems. New power lines often take upwards of 10 years to plan, permit, and build.
But it’s possible to avoid this time-consuming process, at least in many cases, by simply reconductoring lines along existing rights-of-way. Most of our existing power lines have a steel core surrounded by strands of aluminum. Advanced conductors replace the steel with a lighter but stronger core made of a composite material, such as carbon fiber. This subtle shift in materials and design enables the line to operate at higher temperatures, with less sag, significantly increasing the amount of power it can carry.
Advanced conductors cost two to four times more than conventional power lines — but upgrading an existing line to use advanced conductors can be less than half what a new power line would cost because it eliminates much of the construction spending and fees from permitting for new rights-of-way, the Berkeley study found.
“The most compelling, exciting thing is that it only requires a maintenance permit,” Duncan Callaway, an associate professor of energy and resources at Berkeley and one of the authors said while presenting the research over Zoom last week.
The paper highlights a 2016 project in southeastern Texas. Due to rapid population growth in the area, the local utility, American Electric Power, was seeing higher demand for electricity at peak times than it was prepared for, leading to blackouts. It needed to come up with a solution, fast, and decided that reconductoring 240 miles of its transmission lines would take less time than permitting new ones. The project ended up finishing ahead of schedule and under budget, at a cost of $900,000 per mile. By comparison, the 3,600 miles of new lines built under
Texas’ Competitive Renewable Energy Zone program, which were built to connect wind-rich areas to population centers, cost more than double, at an average of $1.9 million per mile.
Callaway and his co-authors also plugged their findings into a power system expansion model — basically a computer program that maps out the most cost-effective mix of technologies to meet regional electric power demand. They fed the model a scenario where the only option for transmission was to build new lines at their slow, historical rate, as well as a scenario where there was also an option to reconductor along existing rights-of-way. The second scenario resulted in nearly four times as much transmission capacity by 2035, enabling the country to achieve a more than 90% clean electric grid by that date.
There are cases where new power lines are needed — for example, to establish a new route to access a high-quality renewable resource, Emilia Chojkiewicz, another author of the study, told me in an email. But she said it nearly always makes sense to consider reconductoring given the potential to double capacity and do so much more quickly. “Unfortunately,” she added, “current transmission planning practices do not tend to incentivize or even consider reconductoring.”
This all seems so ridiculously easy that it begs the question: Why aren’t utilities already rushing to do it? During the webinar last week, Chojkiewicz and her co-authors said part of the problem is just a lack of awareness and comfort with the technology. But the bigger issue is that utilities are not incentivized to look for cheaper, more efficient solutions like reconductoring because they profit off capital spending.
To change this, they suggested that the Federal Energy Regulatory Commission, which oversees interstate transmission, and state public service commissions, which regulate utilities at the state level, mandate the consideration of reconductoring in transmission and resource planning processes, and to properly value the benefits that advanced conductors provide. The Department of Energy could also consider instituting a national conductor efficiency standard, so that all new wires installed, whether along existing rights-of-way or new routes, achieve a minimum level of performance.
Reconductoring isn’t the only no-brainer alternative to building new power lines. Another
study from the clean energy think tank RMI published last week illustrates the opportunity with even cheaper tweaks called “grid enhancing technologies.” One option is to install sensors that collect data on wind speed, temperature, and other factors that affect power lines in real time, called dynamic line ratings. These sensors allow utilities to safely increase the amount of power transmitted when weather conditions permit it. There are also power flow controls that can redirect power away from congested lines so that it can be transmitted elsewhere rather than wasted.
RMI found that in the PJM interconnection — a section of the grid in the eastern U.S. that is so congested the grid operator has frozen new applications to connect to it — these grid enhancing technologies could open up more than 6 gigawatts of new capacity to wind, solar, and storage projects in just three years. For reference, in 2022, nearly 300 gigawatts-worth of energy projects were waiting for permission to connect in PJM at the end 2022.
The cost savings are not just theoretical. In 2018, the PJM grid operator determined that a wind farm expansion in Illinois was going to require $100 million of grid upgrades — including building new lines and reconductoring existing ones — over a timeline of about three years before it would be able to connect. The developer countered that the needed upgrades could be achieved through power flow controls, which could be installed for a cost of just $12 million in less than half the time. PJM approved the idea, and the project is currently underway.
Congress is still
debating how to reform permitting processes. But while that’s still a necessary step, it’s becoming increasingly clear that there’s a host of other outside-the-box solutions that can be deployed more quickly, in the near term. The IRA may have convinced the environmental movement that building new stuff was worth it, but there are still a lot of cases where the smarter choice is to renovate.
Editor’s note: This story has been updated to correct the cost of adding power flow controls to the PJM interconnection.
