Why Transmission Efficiency Deserves Greater Attention
As electric utilities around the world confront growing electricity demand, aging infrastructure, and increasing pressure to expand transmission capacity, much of the discussion has understandably focused on building new transmission lines, upgrading existing infrastructure, and accelerating the interconnection of new generating resources. These are all important priorities, but there is another issue that deserves considerably more attention: the amount of electricity we continue to lose during transmission and the cumulative economic consequences of those losses over decades of operation. While the industry has made substantial progress developing technologies that can increase transmission capacity, we should also be asking whether we are making the best possible use of the electricity we already generate.
Electrical resistance causes transmission conductors to dissipate energy as heat, a fundamental characteristic that cannot be eliminated but can certainly be reduced. These losses increase with the square of the electrical current, meaning that doubling the current increases resistive losses by approximately four times, assuming conductor resistance remains constant. As transmission systems become more heavily loaded, the economic consequences of electrical resistance become increasingly significant. Every megawatt-hour lost during transmission represents electricity that must be generated but never reaches its intended destination. Depending on the generation mix and operating conditions, these losses can also increase fuel consumption, emissions, and the need for additional generating capacity.
What makes this particularly important is the extraordinarily long service life of transmission infrastructure. Utilities routinely expect transmission conductors to remain in service for 40 years or longer, yet conductor selection is often influenced heavily by initial material costs, installation requirements, and maximum operating temperature. These considerations are certainly important, but they do not necessarily capture the full economic consequences of conductor selection. A relatively small difference in electrical resistance can produce substantial differences in energy losses over decades of operation, particularly on heavily loaded transmission corridors. In some cases, the cumulative cost of those losses can exceed the original cost of the conductor many times over.
Consider a hypothetical transmission line where upgrading to a more efficient conductor reduces annual electrical losses by 20,000 megawatt-hours. At an assumed wholesale electricity value of $50 per megawatt-hour, the avoided losses would represent approximately $1 million in annual energy savings. Over 30 years, that amounts to $30 million in undiscounted savings, before considering changes in electricity prices, operating conditions, or the time value of money. While actual results depend on line length, conductor resistance, loading patterns, and other factors, the underlying principle is straightforward. Improving transmission efficiency creates economic value every hour the line is energized and carrying current, and those benefits accumulate throughout the conductor’s operating life.
Independent Research Is Helping Change the Conversation
Recent independent research has reinforced the importance of making better use of existing transmission infrastructure. A 2024 study led by researchers at the University of California, Berkeley, in collaboration with GridLab and Energy Innovation, examined the potential for advanced reconductoring to expand transmission capacity using existing rights-of-way. The researchers concluded that advanced conductors could substantially increase transmission capacity, potentially doubling it in suitable applications, while reducing the time and cost associated with constructing entirely new transmission corridors. Their findings are particularly relevant as utilities struggle with permitting delays, rising construction costs, and growing demand from electrification, manufacturing, and data centers.
The U.S. Department of Energy has also recognized advanced conductors and reconductoring as important tools for addressing transmission constraints. More recently, DOE’s SPARK initiative has provided additional recognition of the opportunity to increase grid capacity through advanced reconductoring and other transmission technologies. These developments are encouraging because they demonstrate growing awareness that modernizing existing infrastructure can often provide meaningful benefits more quickly than conventional transmission expansion. However, while much of this research and policy attention has focused on increasing capacity, the opportunity to improve electrical efficiency deserves equal consideration.
There is an important distinction between a conductor’s ability to carry more current and its ability to deliver electricity efficiently. Maximum ampacity is typically determined by thermal considerations, including conductor temperature, ambient conditions, wind, solar radiation, and allowable clearances. Electrical efficiency, on the other hand, depends heavily on conductor resistance and actual operating current. A conductor capable of operating at very high temperatures may provide additional capacity, but that does not necessarily mean it will operate efficiently. In fact, because aluminum resistance increases with temperature, operating conductors at elevated temperatures can increase electrical losses substantially. This is one reason why maximum operating temperature, while important, should never be confused with overall conductor performance.
Looking Beyond Initial Cost and Maximum Ampacity
CTC Global developed ACCC® Conductor to address several of these challenges simultaneously. Its lightweight, high-strength composite core allows substantially more conductive aluminum to be incorporated into a conductor of comparable diameter and weight than conventional steel-reinforced designs. The resulting reduction in electrical resistance can provide meaningful energy savings while the core’s very low coefficient of thermal expansion helps minimize sag at elevated operating temperatures. These characteristics allow utilities to increase transmission capacity, improve efficiency, and potentially avoid costly modifications to existing structures.
Independent assessments conducted by SCS Global Services have verified that ACCC Conductor can reduce electrical losses and associated CO₂ emissions by approximately 30 percent compared to conventional ACSR conductors under the conditions evaluated. Actual results vary depending on conductor design, electrical loading, operating temperature, and other project-specific considerations, but the significance of these findings should not be overlooked. Reducing transmission losses not only lowers the cost of delivering electricity but also reduces the amount of generation required to satisfy customer demand.
Real-world projects provide additional perspective. American Electric Power’s 345 kV reconductoring project in Texas demonstrated how ACCC Conductor could substantially increase transmission capacity while improving electrical efficiency. The project has been associated with estimated annual energy savings of approximately 300,000 megawatt-hours, illustrating the scale of benefits that can be achieved when advanced conductor technology is deployed across a heavily utilized transmission corridor. Other ACCC Installations around the world have addressed a wide range of challenges involving limited rights-of-way, high ambient temperatures, difficult terrain, long spans, and increasing electricity demand.
Perhaps the larger issue is how the industry evaluates transmission investments in the first place. Utilities and regulators understandably place considerable emphasis on capital expenditures, reliability, and the immediate need to address transmission constraints. However, when conductor selection focuses primarily on initial cost or maximum ampacity, the long-term economic value of improved efficiency may receive insufficient consideration. A more comprehensive evaluation should include projected electrical losses, expected loading profiles, energy costs, conductor operating temperatures, maintenance requirements, and the full anticipated service life of the installation. These factors are not especially difficult to evaluate, but they need to be incorporated consistently into planning and procurement decisions.
This is particularly relevant as the industry considers how to accommodate rapidly increasing electricity demand. Building new generating resources and transmission infrastructure will remain essential, but reducing avoidable electrical losses offers another way to make more electricity available to customers. Unlike new generation, transmission efficiency improvements do not require additional fuel or energy resources to produce their benefits. They simply allow a greater percentage of the electricity already being generated to reach its intended destination.
After more than two decades of working with advanced conductor technology, CTC believes one of the most important lessons is that transmission performance cannot be adequately measured by rated ampacity alone. Mechanical strength, thermal sag, electrical resistance, installation requirements, reliability, long-term operating economics – and delivered power – all matter. The best conductor solution is not necessarily the one that can tolerate the highest operating temperature or carries the lowest initial price. It is the one that delivers the greatest overall value throughout its intended service life.
As the electric power industry continues investing billions of dollars in grid modernization, we have an opportunity to reconsider how transmission efficiency is valued and how conductor technologies are selected. Advanced reconductoring can provide substantial additional capacity, but its ability to reduce electrical losses and conserve generating resources may prove equally important over time.
The hidden cost of doing nothing is not simply the transmission capacity we fail to add. It is also the electricity, money, and generating resources we continue to lose every year when better alternatives are available.
